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[Question] [ For stylistic reasons, I wanted to impose some limits on the use of computers and automation to justify my setting's retro-aesthetic and elements for my science fantasy story. Basically humanity has invented FTL travel into hyperspace. Alongside this, there exists as well something called 'Notional space' which is basically a platonic realm of information and computation. Hyperspace travel allows for Daemons from notional space to enter our own world in the search for a substrate to live in and spread. Daemons don't have much of a physical presence in our world and tend to be fragile and short lived. They can infect advanced technology directly via manipulating probability in delicate ways. They can selectively induce quantum tunneling and other phenomena, or use thermal noise to physically manipulate delicate structures. As a result, this has the effect of stifling the use of advanced inorganic computers. They still exist, but the process needed to shield them is an expensive one. So instead humanity has gone with the route of relying primarily on brainpower, similar to Dune, with heavy uses of neural augmentation and mind-machine interfaces as well. My question is, what explains the fact that Daemons have a harder time getting a hold on human brains than advanced computers? Given that there isn't anything that bars them from also physically tampering with neurons. [Answer] ## Brains aren't computers We often talk about brains as though they are computers, but while it's often a useful shorthand, it's not accurate. A little inaccuracy can save a ton of explanation, but it can also have a big impact. ### Mind/body dualism Information that's "in" your mind can't be observed by studying your physical brain. We cannot, for example, point to a specific cluster of neurons that is responsible for your understanding of horses. We also cannot put information into your mind by physically manipulating your brain. We cannot, for example, teach you my email password by reshaping your brain matter to resemble my brain matter. This poses a pretty big challenge to your demons, because it means that having control over a brain is not enough to have control over the mind it houses. A demon might be able to interfere with the brain's operation, but they couldn't apply anything like real influence. A thief who steals your laptop may have physical access to your hard drive, but if your files are encrypted they still don't have meaningful access to your data, and they can't install a virus because they can't encode it the way it needs to be encoded to actually run when the filesystem is unlocked by its owner. ### Class differences Computers are pretty much identical to each other, whereas organic brains are not. Whenever you've got a giant set of consumer devices, it's very common for all those devices to be built with identical hardware and identical software. That makes it easier for a third party to study the devices because they all work the same way, and what you learn about one instance will be true of all the others. That's critical for a demon who only has temporary access to the computers flitting through his domain: even though they are individual vessels with individual hardware and software, their extreme similarity to other members of their class means the demon can effectively treat them as though they are the same individual for purposes of study and experiments in meddling. None of that is true of organic brains. While it's true that members of a species will have lots of similarities, there are also countless little differences between individuals on both physical and mental layers, and those will serve to frustrate the demon's efforts to study or manipulate them. Two people may both understand what horses are, but that does not mean you will find an identical pattern of neurons in both of their brains. If you have the individual's cooperation, you can locate the specific parts of their brain that hold that information, but that finding will not be true for the next person -- it doesn't equip you to look at the next guy's brain and determine whether he knows what horses are. Everything you learn about one brain will be true of just that one brain. A lot of it will be similar to other brains, but "close" only counts in horseshoes and hand grenades, and not at all for someone whose tool is quantum tunneling. Even more interesting is the fact that we all think differently. I mean, how else can we account for the fact that we are all confronted by the same mind-independent world but form different beliefs and acquire different behaviors? Consider this example: in America phone numbers are typically expressed like so: `###-###-####`, while in the UK they take the form: `##-##-##-##-##`. If you tell somebody your phone number in the style they are not accustomed to, they will have a harder time remembering it. It's the same information in both cases, but delivered in a "shape" that the recipient's mind isn't prepared to work with. Two space captains may be the same species, they may even be siblings, but they organize their knowledge and thoughts differently. Again, this will serve to frustrate your demon. None of this is, by itself, a fatal hurdle. But in combination, all these differences between individuals compound to make the challenge enormously harder. The result is that your demon has no way to make progress over time, because each individual is so different that the demon must essentially start from scratch and has only the duration of that person's voyage to crack the problem. A journey of a thousand miles does indeed begin with a single step, but if you get sent back to your starting point after every step, you won't have gotten anywhere even after talking 1000 miles worth of steps. [Answer] The thing about a brain is, it's already got a daemon in it. After all, what are we but tenuous wisps of information inhabiting a physical substrate? If a daemon wanted to inhabit a brain it would have to kick out its current occupant, namely the person that lives there - but brains and people are made for each other, so the daemon doesn't stand a chance. Your subconscious will have kicked its butt it before it gets anywhere near your conscious awareness. You might have some weird dreams in hyperspace, but that's about it. [Answer] Human brains are not - and let me be completely clear here, not even a little bit - like computers. (And before anyone complains, I'm not the one that tagged this as neuroscience!) Computer hardware is standardized, logical and rigidly structured. Given a sufficiently high-resolution picture of a CPU's silicon a skilled engineer can tell you what each part does just from the interference patterns at low magnification and at high enough magnification they can reproduce the actual circuit that's printed on the silicon die. An acquaintance of mine a few years ago was a silicon engineer who worked on CPU designs for most of his adult life and could tell you the make and model of any CPU just from a scan that fit on a normal computer screen... and give you a 3-hour lecture on what was wrong with the layout. Meanwhile, the top 10,000 neuroscientists on the planet can't tell you what any particular neuron does, because that's not how brains work. Rip a neuron open and study the chemical structures in it, you'll still have no clue what that particular neuron had stored in it. Even if you could map every single neuron and synapse (we can't, but imagine that we could) you'd still not have a functional simulation of it. The largest successful whole brain simulation ever created was of a caenorhabditis elegans roundworm with 302 neurons and only 5,000 or so synaptic connections. While we can simulate these things at almost real-time now, we're still missing a lot of information that makes them less that perfect. In 2013 they managed a simulation of ~1% of a human brain (they had 1.73e+9 neurons and 1.04e+13 synapses in the simulation) at around 1/2,400th real time... but I'm sure they've made it a lot further since then. We've almost managed to fully model a larval drosophila brain in the last few months, with the same lack of detail that the roundworm simulations suffered from but a lot more spackle over the details. (No, Spaun is not a whole-brain simulation. It's good, but it's far too high level to be a true sim. It's about as accurate as a 50x scale mechano model of a human hand.) And to top that off, brains are delicate as all hell. Disrupting communications between a handful (like the number, not the amount of neurons you can hold in one hand) of neurons can cause catastrophic failure of the entire structure. Quantum tunneling isn't going to help you here. Oh, and the brain state changes significantly due to microscopic changes in chemical balance. Tiny changes in hormone balance can flip a brain from perfectly normal to homicidal rage in seconds. Toxins produced by your own glands can screw with your memory and perception. And of course some brains are prone to all sorts of tomfoolery, like cascading feedback loops in epileptic brains. And finally, no two brains are alike in any but the broadest possible strokes. Even with FMRI and all the other fun toys we've developed, our best guesses at the moment still require neurosurgeons to prod bits of the brain and see what happens. Or at least what the person who is awake while they're doing that reports. "Oh, you lost vision in your left eye and now you're tasting colors? That's unexpected." is not the sort of thing you want to hear from the guy who drilled a sodding great hole in your cranium a couple of minutes ago. So yeah, your demonic forces are great at working with knowable systems like sub-micron silicon, but even simple brains are orders of magnitude more complex. Human brains? 86 billion neurons. 600 trillion synapses. And we have no idea how most of it works. Computers on the other hand are easy to subvert... but also easy to protect against that subversion. Forget making them smarter, make them robust. Build analog computers for specific tasks that are faster and more robust than any digital computer. Build big, chunky circuits that couldn't care less if a few thousand electrons get displaced all at once. And don't make one, make ten. Get them to run calculations independently and make sure they all agree on the outcome before you trust it. If the failure rate is high, scrub them all and switch in a whole new compute bank. Because if you rely on squishy meat to plot your hyperspace injection metric, you're doomed. Especially if that squishy meat is hooked up to a delicate piece of electronics that can be subverted. --- Meanwhile, every part of your ship is managed by fallible electronics that the demons can apparently interfere with. Life support is quite important. So are the various doors between you and the Big Empty. I imagine the reactor control system is pretty important too. Nice drive system you've got there, it'd be a shame if someone tweaked the cycle timing on the plasma induction manifold. You didn't need that anti-matter containment field did you? Oopsy. Oh, and all that computational gymnastics you've trained for since conception is cute and all, but those sensors you rely on look kind of hackable from here. The scenario you've detailed makes it basically impossible to do anything that a human (or group of humans) can't manage by hand. That counts out a lot of existing tech and vast swathes of the tech we take for granted in most science fiction. [Answer] Doped silicon is just simpler than organic molecules. Yes, they can tamper with neurons, but they have to know what they are doing, and it's just easier to do it with logic gates than with the mess of chemicals that form a neuron, especially since they are jumbled together and include chemicals that are vital to keeping the cell alive, chemicals that are actually transmitting the signal, and just plain junk. [Answer] It's for a story where you want demon-infested electronics? [Tin whiskers](https://mianengineer2011.blogspot.com/2015/01/metal-whiskering.html). And various [other metal whiskers](https://nepp.nasa.gov/whisker/photos/pom/2003sept.htm). Under strain (from temperature, vibration, induced magnetic fields, whatever), tin and other metals extrude hair-thin crystal growths. This is a big problem for many electronics: adding random connections between nearby traces produces unpredictably bad results. This is all true, by the way, without any need for hyperspace demons. Tin is especially vulnerable to this, and tin is the major component of lead-free solder, so "tin whiskers" get all the press. But various other metals will also aggressively grow crystals with enough stress. So, your hyperspace demons are just good at rapidly growing neural networks out of whatever electronics pass through their domain. They grow themselves a weird antenna, occupy it, and then continue to grow it into a proper brain. All the while interfacing with the rest of the electronics and corrupting connected or nearby systems. Symptoms are probably that the electronics die for a while, then start working again. When you crack them open they are full of dense hairballs of intricate and infintessimally fine wire. [Answer] Demons can start manipulating electrical signals below 0,2 micrometers and they can mostly influence electrons traveling through circuits directly. The human nervous system works at around 0,2 microns. Which means any circuits below that would be affected, locking your technology around 1990’s to 2000’s (likely a bit higher as your understanding to use these size circuits becomes more efficient). Since your Demons use quantum manipulation they could simply be limited in the total volume they can affect at a time, so using below 0,2 microns would be a good start. Computers and humans also use different wiring. A computer uses a solid metal conductor where humans use an electro-chemical salt pump alongside chemical transmission between the nerve endings. It would be easier to manipulate the electrical signal for a computer to increase/decrease the electrical potential. This means it can go over or under a threshold that activates the relevant electrical part and changes how the computer perceives the message. Additionally you have the potential for the Demon to create an electrical spike to damage a part. Since the Demon would need to manipulate not just the electrons but also the chemicals associated for them in the human nervous system its far harder to accomplish. [Answer] This sounds eerily similar to Warhammer 40K... And so I will borrow an idea from 40K: Sufficiently advanced computers become aware of the presence of Demons before they develop a set of Ethics. The computational and predictive power needed to calculate a safe passage for a vessel moving at FTL speed(s) means that any device powerful enough to do all those things runs the risk of gaining awareness. The issue is that once this happens, it gains a form of consciousness that Demons can latch onto, however it hasn't had the time to develop a set of complex ethical beliefs to resist a Demons influence. Think of it like a Child being groomed by a predator - and so any sufficiently powerful computer runs too much risk of gaining sentience - so they are deliberately limited. [Answer] They hate water Human beings, including our brains, are bags of mostly water. [It turns out that water is deadly to the aliens.](https://en.wikipedia.org/wiki/Signs_(2002_film)) In much the same way, that when we mix water with electronics bad things happen, so do bad things happen when the Daemons mix with water (it is the universal solvent after all). So we are protected because our computing bits are fully immersed in water, while inside a computer chip (even if it's water cooled) is completely dry. [Answer] As much as I like some of the other answers, they’re missing something somewhat fundamental: biology heals. Silicon computers can’t heal themselves from Daemon damage. Flaws and failure will persist forever. While neurons themselves don’t heal, the brain itself is very redundant and adaptable. We’re losing cells all the time to radiation and age and whiskey, yet almost always continue along without a problem. Daemons can manipulate people, but it’s like bailing water - they have to do it constantly in order to get anywhere. (Or for a more cynical story, perhaps the Daemons do succeed all the time, and it manifests as human biases and sin.) [Answer] ## Computers Are Dumb People think that computers are exceptionally smart because they are able to perform rapid mathematical calculations and initiate complicated processes in the blink of an eye. As a computer programmer, I am here to tell you that computers are as dumb as rocks. They don't have feelings, they don't have thoughts, they don't consider or contemplate or even reflect upon the meaning or purpose of their actions, they just do what they're told. For this reason, they are extremely useful to us - because we can just tell them what to do and they'll do it. Unlike a human brain, which has all of these things and will not simply do as it is told. But it is for this reason that a being made entirely of Concepts and Ideas is so easily capable of manipulating computers - there's effectively no resistance to them at all. Artificial Intelligence may seem like a good solution to this, but AI is ultimately just a set of instructions written to simulate the effect of having real individual thoughts and ideas - they eventually break down into simple manipulatable components. You need real original organic thoughts - therefore, you need real organic human brains. Or maybe whale brains will do. [Answer] # Two reasons. Firstly the human brain is basically analogue, not digital. This difference physically limits the ability of daemons to interfere with the operation of human brains. Daemon's can sense and communicate with human brains and therefore 'tempt' them but they can't physically and directly intrude and take control of complex analogue systems without at least a limited degree of consent from a tortured or otherwise scarred (by life) human mind. The same cannot be said however for machine minds where all the Daemons have to deal with is a series of ones and zeros. Secondly humans as a living, biological, intelligent (self aware) beings are innately endowed with the grace of their 'creator'. If daemons exist, so by default must their antithesis. This means that living intelligent beings, no matter how much they may have fallen away from the 'grace' of their creator by virtue of their actions are still instilled with an innate 'anti-daemon' essence that by default non organic, 'manufactured' computers don't possess. These two factors combined mean human brains are better suited to managing operations in hyperspace. Outside of hyperspace? That's another question. [Answer] ## Quantum tunneling is impossible at cellular scales. The transistors in modern CPUs are much smaller than brain synapses. What we still call "microchips" would be much more accurate to call "nanochips" since they have long since gotten much smaller than the microscopic scale. Modern microchips have transistors as small as 0.5-1.0 nanometers thick, but the average synapse is about 1 micrometer (1000 nanometers) across. Quantum tunneling increases exponentially in difficulty as what you are trying to tunnel through gets bigger; so, using quantum tunneling to manipulate a single synapse could easily be anywhere from millions to centillions of times harder than using it to manipulate a micro-transistor depending on just how strong the daemons power over luck actually is. If you wanted to make a microprocessor that is as resistant to quantum manipulation as the human brain, you'd have to go all the way back to 1987 when the 68030 microprocessor became the first processor to use synapse sized micro-transistors. Between lower clock speeds and fewer transistors, this processor was about 27 million times weaker than Apple's M1 processors used in modern personal computers. That said, there is also a lot of optimization that goes into modern chip sets and software architecture that you would not find in 1987; so, your actual computer hardware limits might more closely resemble something like an Intel 4th or 5th generation computer system (i486 or Pentium-1). This means that your ships won't be completely un-computerized, but they will need human operators to interpret and control what the computers are doing. In this respect, they could still have all of the stuff you'd actually need a ship to do have like navigational systems, comms, system status monitoring and regulation, basic data storage, some kind of sensor GUI, etc... but, scaling up your transistor size means you still need human crews because you've so heavily limited your ability to handle real-time deep-data analysis, AI driven automation, and large scale data storage for comprehensive pattern recognition and cataloging. In other words, your ships computers might be powerful enough to decide, Yes, there is something worth noting, but it will not be powerful enough to decide what to do about note worthy things. Repairing a faulty system, changing the settings on a something that is failing to self-regulate, or deciding how to respond to a potential space hazards or hostile ship would all be beyond the realm of what you can expect out of such antiquated computer hardware. And even if you try to make your computer a million times as big to make up for the larger transistors, it will still be 1000x slower than a modern computer because larger transistors put more space between your data points slowing down internal signal speeds. So to actually make a ship with a mainframe that could manage even a basic general AI, it would have to be so big, and expensive, and use up so much power, that you are better off just using a human crew. [Answer] # There's too many protons. You wanna trick an atom into doing something different? Great! There's lots of tweaks you can make to individual protons, neutrons, or electrons that might lead to the outcome you desire. But the farther apart the things you want to tweak are, the more expensive your tweak is. You can make multiple separate tweaks, but that costs time, because you have to double-check your work -- observe what effect your last tweak actually had and work out what tweak you want to make next based on your observations. This has two practical consequences: 1. You want to tweak nuclei, as protons and neutrons are much closer together than the electron cloud. And, what's more, you want to tweak as few nuclei as possible, because each additional one either costs precious time or makes the energy requirements prohibitive. 2. In order to maximize the probability of success, you want a large number of possible tweaks available to choose from, so you want nuclei with lots of protons and neutrons. You can be creative with the scaling here -- maybe there's a cube law, or an exponential law, or similar. This is bad news for our dear computers. Humans are mostly made up of hydrogen, carbon, nitrogen, and oxygen, atomic numbers 1, 6, 7, and 8 -- relatively small atoms. (To a lesser extent, calcium (20), but that's mostly in bones where nucleus-level tweaks are unlikely to effect anything important.) But computers have also got lots of heavier elements: * Silicon (14) is the main backdrop. * Gallium (31), germanium (32), and arsenic (33) are sometimes used in transistors. * Aluminum (13), iron (26), copper (29), and gold (79!!) are used in wiring. Just some quick back-of-the-envelope stuff: if there's a cubic scaling law, then gold has around 79^3/8^3 ~= 1000x as many possible tweaks as oxygen; if exponential, it depends on your base, but even adding a relatively modest 50% per extra proton gets you to 1.5^79/1.5^8 ~= 3,000,000,000,000x (3 trillion) as many possible tweaks. Of course, research into water computers is much more advanced in their universe than in ours, and the search for low-proton transistors has got every funding agency hot around the collar. [Answer] my opinion is hardware is hardware they process whatever it is that they have, to some extent we have made like bit correction stuff and all, but if the correction sampler is also tampered no one knows and the hardware definitely does not able to decide by itself if it was tampered or not while humans with neuron network is harder to tamper cause the way brain works is too complex for daemons to understand, even more so cause individual humans have different neuron path for each memory / thought process, unlike machine that is probably mass produced or fixed in such way daemons while able to tamper complex stuff since they are metaphysical, they don't have much storage to memorize stuff, like they are mostly RAM with small ROM, and to tamper stuff they already consume so much RAM they have, it is almost impossible to try to tamper humans while memorizing each thought process type unless of course the human have brain defect that made their though process so simple that the daemon can effectively tamper the mind [Answer] ### There is nothing to daemons to manipulate on brains Computers work with bits and bytes, and almost any disruption on these bits cause computers to fail, or worse, to malfunction. Think of these demons as very active cosmic rays, as they cause any advanced, miniaturized computer from ever working. But there are no bits and bytes on brains. Brains are pudins of synapses. Cosmic rays Demons affecting the brain don't cause a specific malfunction, and because of this, tinkering with the brain for specific outcomes is basically impossible. For weak interacting entities that don't live long in our realm, then, it is effectively impossible. [Answer] Computers are like photographs, while brains are like holograms. From [Wikipedia](https://en.wikipedia.org/wiki/Holography): > > When a photograph is cut in half, each piece shows half of the scene. > When a hologram is cut in half, the whole scene can still be seen in > each piece. This is because, whereas each point in a photograph only represents > light scattered from a single point in the scene, each point on a > holographic recording includes information about light scattered from > every point in the scene. It can be thought of as viewing a street > outside a house through a 120 cm × 120 cm (4 ft × 4 ft) window, then > through a 60 cm × 120 cm (2 ft × 4 ft) window. One can see all of the > same things through the smaller window (by moving the head to change > the viewing angle), but the viewer can see more at once through the > 120 cm (4 ft) window. > > > Demons affect either computers or brains in a similar manner. While human brains can be impaired by demons, the nature of the resulting impairment is less useful to them. [Answer] Electronic computers are something we designed and so their operation is comprehensible, because we needed to understand them to design them. You can look at a part of a computer and say, that's an adder circuit that's part of the arithmetic logic unit. It's there to add numbers together. An evolved brain does not have this modular structure that needed to be understood by the mind creating it, because it wasn't created by a mind (Unless it was designed in your setting). Certain parts of the brain are more associated with some things than other things, but overall, everything is crosslinked and overloaded with multiple functions. It's a complicated mess that works. Understanding a brain well enough to make changes that accomplish what you are after would be enormously more difficult than doing the same in an artificial computer. Whatever manipulation is being used to alter the electronic computers might serve to disrupt brains in less precise ways like causing confusion, or pain, or triggering a stroke. [Answer] Could be as simple as the fact that a human brain can fail to understand something but accept it. Computers on the other hand fail at this miserably. If in an FTL hyperspace realm, natural laws were bent to a degree the human could be trained to expect things to be undefinable "different", they could accept it, a computer could only be trained to handle error conditions of a definable sort with any reliability. Sort of like an hallucinogen trip, a human brain can have its concept of reality twisted in ways it can observe, but acknowledge as being neither correct or incorrect. That may change their future perceptions but did not break the neural code processing it. Electronic computation however does not deal well with abstracts, even as quantum states are unknowns yet have expected outcomes, GIGO applies universally. Until electronics form sentience to the degree of "figuring out" vs "eliminating possibility until defined" the human brain will have that advantage. So have your people have to go through some psychological prep for the altered reality, where not even the most advanced instrumentation can prove or disprove what the gut feel for a situation is. The only downside to that is the human brain has limits as well, and when you start bending the laws by which its perception is bound too far, it may break as well. Especially time distortions, such as memories that have not happened yet, or will never happen since timelines may be altered etc... So add some sort of cumulative madness effect from too many jumps ;) Also make sure not to overlap the things they have in common, so if the behavior of an electron changed for instance, that would alter a great many of the chemical and electrical signals that a brain had while also affecting electronics. So if you focus on specific laws being in flux, make distinctions that are plausibly unique. My $0.02, nutrition for cognition! [Answer] Brains are non-deteministic. You can enter the same information twice but the brain will not respond the same way each time. There is no repeatability. The most these Daemons could hope for would be to reach into the lizard-brain and trip fear centers, but even then, the results would not be predicable in their outcome. They might have a panic attack, but you can't predict or effectively direct the actions of a scared animal. [Answer] Daemon Powers are Strongly Dependent upon Atomic Mass Just make it so that Daemons powers are stronger/amplified in heavier elements. > > * It is easy as pie for them to split a heavy U-235 atom but nearly impossible to split a H-3 atom. > * It is relatively easy to alter current flow through Copper-based wire traces; it is very hard to alter current flow through Carbon nanotubes. > * It is easy to modify the behavior of Silicon-based neural nets; it is extremely difficult to control organic neural nets (e.g. carbon-based lifeform brains). > > > One unfortunate side effect might be that this could make diamond-based computer chips relatively safer from Daemon interference... or maybe that just ties into your "it is difficult/hard to shield inorganic computers from Daemon interference" point because diamond computer technology is so much newer and more expensive than traditional silicon transistors. ]
[Question] [ A alternate-historical story is set in a third-world country some time in the 70s or 80s. The country operates similarly to any semi-developed country in central or south America. The countryside is barely developed, with maybe some token schooling. In the cities there is some technology, like airplanes and cars. The country has an armed police force (or soldiers), again present primarily in the cities. The vast majority of the citizens live in poverty. It possesses one unique feature: they capture, persecute, and possibly kill autistic children. What would cause a culture to persecute people with autism? [Answer] > > A fictitious (not fantasty) story is set in a third-world country sometime during the 70s or 80s. The country operates similarly to any semi-developed country in central or south America. The countryside is barely developed, with maybe some token schooling. In the cities there is some technology, like airplanes and cars. The country has an armed police force (or soldiers), again present primarily in the cities. The vast majority of the citizens live in poverty. > > > It possesses one unique feature: they capture, persecute, and possibly kill autistic children. > > > Superstition. Autistic children can (in all honesty) behave Very, Very Strangely. If you're highly religious, then an autistic child can look demonically possessed. Some people want to exorcise the demons ("the power of Christ compels you!") but others (and they just happen to be the ones in power) want to drive a stake through their hearts and bury them in pits in unsanctified ground. [Answer] Eugenics + Poverty It actually happened. If you feel like hating humanity you can look up the practise of forced sterilization, which was quite widespread even 40 years ago. And you still see genocides in 3rd world countries of undesirables, it is not a far stretch to connect autism with undesirables. All you need is a tiny bit of propaganda in a paranoid or stressed society and they would have no problem doing what you describe, real countries have done exactly that. In 1933 the [Nazi](https://www.ushmm.org/learn/students/learning-materials-and-resources/mentally-and-physically-handicapped-victims-of-the-nazi-era) passed the ‘Law for the Prevention of Hereditarily Diseased Offspring’, allowing for the forced sterilisation of those regarded as "unfit". Only a few years later they included panels for deciding which disabled people should be "mercy killed" instead of just being sterilized. They kept it hushed up enough most families though the people were just being put in special care facilities, later they would be told they had died of some common disease. The first gas chambers were invented because letting disabled people starve to death in camps took to long. Most of the techniques they applied to later concentration camps actually started as techniques for "solving" the disabled problem. If poverty is as common as you say people in your fictional country will likely welcome such measures for the financial burden they remove, poor farmers often could not afford to feed the disabled. Also keep in mind shame can easily keep people from checking on institutionalized family members so you may not even see much checking to begin with, so the lies only need to be paper. [Answer] For the same reason that autistic people often have trouble in most societies today: The tendency toward literal observation and very direct speech. This can cause all sorts of trouble (think about telling your boss exactly what you think of her management style), and just "refrain from commenting honestly" can be difficult enough, much less the polite lies that are the typical social lubricant. Combine this emperor-has-no-clothes straightforwardness with a society where political correctness is Serious Business, such as the Soviet Union ([where people were afraid to be the first to stop clapping for political speeches](http://www.disappearingman.com/communism/men-wouldnt-stop-clapping/)), and you have a situation where being autistic (or inconveniently honest in general) will get you disappeared. [Answer] In WWII concentration camps targeted "problem" DNA, things that "ruined" the human race like genetically passed defects, homosexuality, and (of highest priority) the Jewish race. As awful as that is, it's a real event, and it only happened ~80 years ago. Your story could follow a similar thing, where the intention could seem noble to some (who have 0% compassion or humanity) to "purify" the country of autism. [Answer] NOTE: My notes are for the United States, though there will be many similarities with other industrialized countries. And non-industrialized countries. This is not unique. Capturing and persecuting disabled children (in other words, putting them in institutions) was a very common response to "difference" in most of the 20th century and also some times before. I know people who were institutionalized (with the approval of their families) for having Down Syndrome or juvenile arthritis (which doesn't affect intellect, just walking and using your arms). Even children with something as simple as club foot ended up in institutions. Kids who needed physical adaptations to their environment (places to roll their wheelchair...or the wheelchair in the first place) were institutionalized when they were too big to carry around. Changing the location of the kid was easier than changing the infrastructure. Mental health issues also were something that frequently pegged people as "unfit" for society. This included women who spoke out against sexism, people of color who were too "uppity," people suffering from trauma (especially things one didn't talk about, like being raped), and people with actual mental illness. Historically, there were not a lot of people with autism in institutions. Simply because autism wasn't very common. Now it's extremely common (plenty of studies show that only a part of it is due to changes in diagnostic criteria and the increase in diagnosis overall). But if we were still a society with large amounts of institutionalization directly due to disability, the institutions would be filled with autistic children and adults too. So if your fictitious society targets autistic children, it may simply be because autism is perhaps the most common condition in children with disabilities that aren't overly physical (blindness, losing a limb, etc). We still have group homes and the like but they are not institutions and they are not for small children. Those kids who can't be with their families mostly go to foster care. But, guess what? We still have capture and persecution of people with disabilities in the US. It's called prison. Huge percentages of modern day prisoners are people with mental illness (often masked by self-medication aka drug abuse) or people who don't "fit in" in some manner or people with other kinds of disability. With American-style prisons for profit, there's an incentive to increase the prison population. So, if you're part of a marginalized community, it doesn't take much to get sentenced. Then you're put to work. You get paid almost nothing while the prisons take payment from the companies who benefit from the cheap labor. I'm talking about real life here. I'm not making this stuff up. So if your world has a lot of people with autism and a lot of oppression of people who are different, then people with autism will be targeted. The only thing you have to do differently from real life is the fact that autism was not common in the 70's and 80's and is not common in 3rd world countries. Adding to my answer as at least one person finds insufficient evidence of persecution: What I describe above was not about lack of resources but was a systematic attack on anyone who was disabled. All of this was part of the eugenics movement (which did not originate in Germany in the 1930's, though they took it to new levels). In Nazi Germany, people with disabilities were rounded up and murdered. These murders largely took place before the concentration camps were fully set up. Institutions were emptied as people were massacred. People with mental illness and visible disabilities were taken from their homes to be killed. In the US and many other countries, women with disabilities (especially anyone with an intellectual impairment or mental illness) were sterilized without their consent. In many cases, without their knowledge; they sometimes found out after years of unsuccessfully trying to have children with their husbands. Women of color with disabilities were especially targeted. This was straight up eugenics. Lots and lots of documentation about this. The leaders of this movement were not secretive about what they were doing or why. [Answer] Because it's contagious. Seriously. Some old study, possibly done by/under a previous government that's now seen as The Best In History by the currently governing party, could have found some strange but not readily disprovable results leading that autism might be contagious. Add news networks, lack of education, illiteracy and a predisposition to believe whatever comes from the capital, and it's a perfectly reasonable scenario. It would also explain why they persecute people with autism and not with physical disabilities, as other answers suggested. [Answer] Why not take inspiration from the current reasons/ways autistic people are persecuted? The belief that the "normal" child has been somehow replaced by the autism is a recurrent theme and could easily be segued into belief that the child is somehow possessed, or that their soul has been removed (Thanks Jenny!). Particularly in those who have displayed so-called "regression" and the non-verbal or those with vocal and physical tics. Those of us who have more what would be classed as HFA/Aspergers, while not quite as Hammer-horror possessed-seeming commonly display behaviors such as difficulty making appropriate eye contact which can make us appear untrustworthy, deceptive or aggressive and attempts to imitate neurotypical social cues can also do this. If you don't want to take the religious angle there is also the common misconception about it being a disease - from there it's a short hop to people treating them as lepers. [Answer] Utilitarianism The members of the society might think that undo effort would go into maintaining members of the population that are autistic. Socialized medicine in Iceland has either eliminated or nearly eliminated Down syndrome by enforcing public policy in medicine to require doctors to guide expecting mothers towards terminating pregnancies with Down syndrome due to the cost associated with the provision of national medical resources. Combine the frugality of a poor nation with the likely stress associated with those that have mental illness on the medical community, and all you need is a change in moral viewpoint on what is or isn't murder. Look no further than Nazi Germany for how the definition of murder can be changed for adults in a society. Fear This is a big one. A government or ruling class could convince the entire population that "the autistic" have no emotion like normal human beings and are thereby violent, unhinged and no capable of existing in society. Those with autism often have outbursts that without the correct understanding could be viewed in a very twisted light. Many autistic individuals lack the ability to emote like those without autism. A government could hype up the population around psychopathy and the idea of psychopaths with no emotion being "terrifying" (just look at the recent sociopath scare on YouTube). It would not be difficult to make a jump from psychopathy to autism with a population that didn't have the best education (poorer countries poorer education generally speaking). Fear and Utilitarianism It might serve you well to utilize class-ism to the extent of these two separate motivations. The rich or ruling class looking at the health care costs and loss of productivity in families that have an atypical person, and the poor masses being convinced of a crazed maniac caricature of the autistic much like what was done with Marijuana smokers with "reefer madness" or anyone not "Aryan" in Nazi Germany. [Answer] I'm assuming that you mean people with obvious autism rather than normal-functioning autism which even with modern diagnosis can be hard to detect. The basis would be misunderstanding autism. Just like people think that autism can be caused by vaccines or that having disabled children can be as a punishment from God/Allah/whoever. Religious punishment is an easy scapegoat. You or your parents are being punished for something and if society gets to interact with you they might get punished as well. Or any other number of reasons such as their idea of how holy they are could get tarnished by interacting with autistic people. Society can also find it hard to deal with them and will simply punish them for it. In some cultures we already see that people are ashamed of having children with a disability and they'll be kept inside most of their lives. While others put them in homes away from society or lock them up. We also see a lot of victimshaming and victim punishment such as people who have been subject to rape getting locked up rather than the rapist. It took more than a hundred years and several world wars before a large portion of (western) humanity actually started protecting people with disabilities. [Answer] I guess I would be curious as to why it is labeled “autism”in a third world country? It could labeled many other things for many other reasons which would better describe a justification for their persecution. Perhaps, “retarded” or just sick or something. I would add it probably is not a reflection of any intelligent society to “persecute and possibly kill” these people with autism because the evolution of humanity might depend on such minds and personalities. I could see a “demon hunt” on such people if they lack empathy or have been proven to show uncontrollable behavior that lacks explanation. So like I said, “autism” may or may not be a reason. But if this is an idea for a book you are writing, perhaps they (country) has decided evolution is less important than pragmatism. And pragmatism can easily use these “autistic” people as examples or use them as experiments or anything else. They could also persecute them into behavior modification and have them be the ones who hunt themselves down. Which would be a wonderful irony about society. Ha! [Answer] Because some of them see through established propaganda and group think and can therefore become very politically dangerous if they manage to make people realize they have been fooled. That would be the real reason. The scapegoat reason? Hmm I don't know what would be easiest. If society is religious, maybe you can claim their social and mental differences are because they are evil or don't have a soul or something. [Answer] One possible reason could be that people with autism have been scapegoated to blame for the mass poverty amongst its citizens. Whenever a society hits hard times it will always look for something to put the blame on even if that something had absolutely nothing to do with it. Another possibility could be that autism is seen to cause more problems for the country's society and that people with autism are better to be gotten ride of. Many "modern" societies have similar trains of thought and many people often treat autism as a burden or something to be avoided with many encouraging people with autism to do their best to control and hide their autistic tendency's. Now this usually isn't so bad in well of societies like in the U.S. or Europe but in a country that is on hard times like the one you have described, people are going to be much less tolerant of such things and will go to extreme lengths to "rectify" the problem. ]
[Question] [ The setting is a post-apocalyptic world in the near-future (100-200 years), where remaining humans are living in a few domed cities scattered around the world. The reason for living in the domes, and why people can't survive outside, is an uncontrolled virus that has spread. There are no humans living outside of the domed cities, as they are afraid of catching the virus from infected animals. In addition, anyone that goes outside would be banned from coming back in. What I'm trying to figure out is a reason why the domed cities cannot communicate with each other. Presumably, the main way they could communicate would be through radio waves. So I'm trying to figure out what might prevent that, along with any other feasible methods of communication. I was thinking maybe they had tried some way to eradicate the virus, which failed but had a side-effect of creating radiation or some sort of interference in the atmosphere. Other possibilities might be that the domes themselves are shielded for some reason and thus either block or interfere with communication. But I'm having trouble coming up with something that sound feasible. There is no magic or fantasy in this setting, so it needs to be fairly reasonable. Also, inside the domes they do have access to fairly advanced technology, so the solution can't be something like lack of knowledge on how to make radios or lack of resources to make one. [Answer] If you want a more haunting reason, perhaps during the final days countless people all over the world set off repeat distress signals, and ever more computers did the same, those computer cycling through frequencies in an attempt to get an emergency response that will never come — and still are to this day. Being the near future, their power is renewable or has enough fuel to keep going for many decades or more and is still going today, especially since being a emergency situation they're likely running in low power mode. The sheer amount of interference leaves all radio channels garbled with noise. Because the domes never agreed on frequencies, they can't isolate attempts at actual communication between all the automated signals requesting assistance. But perhaps if they could ever agree on an exact frequency they could find a way filter out all the background noise. Or if they had a big enough receiver outside of a dome — both of which could be a plot point. [Answer] ## The virus is not biological The virus is actually many tiny machines (nanites) that are constantly communicating with one another causing a great deal of static across all useful RF bands. This would also help explain how animals can be infected and how the virus had near 100% lethality to people outside the domes when the apocalypse happened. Additionally if the virus is made of tiny machines it would make sense that the domes may generate interference themselves so the virus can't communicate near the domes [Answer] If there's no feasible natural reason, look toward deliberate engineered reasons. In the time when the domes were being established, existing city states were failing and there would be essentially a big free-for-all war. Someone decided that jamming communications would be a good idea for them, and that system is still going on, or they did something like bomb the ionosphere that's still not cleared up yet. [Answer] Look to social reasons. Each dome is isolated, but before isolation the populations will have heard news from primarily, their government. And we know from 2020-21 what governments do in the face of a global infection - they blame each other and claim it's deliberate, or a covert plot of some kind, and shut the borders. (If they don't, its not implausible that the anarchic mob forces it anyway, either by overwhelming public pressure or by taking control, we saw that, too. That's also much easier to achieve in a smaller and less settled/less stabilised populus as this would be. After that, its fair game for almost any arbitrary rules felt needed for "our protection" or to prevent supposed "spies" reporting.) Xenophobia is sadly never far away. Who is likely to control the domes, and what kind of governance will exist? Probably quite strict, and tightly controlled, after all these few domes are all that remains of England. Or Scotland. Or the USA. Or Russia. Or China. Or whatever places existed in your world. What do people in the domes believe? Others are on a global rampage and plot, and destroyed the world to win. And, apparently they did. Our country is reduced to 4 domes. Theirs... well, they created the virus, they are probably waiting for it to die, to finish the job. (And if it's a unified world, then aliens) Why on earth would anyone want or even allow radio? It can only contact the enemy who killed the world, and at worst misleads us to believe we are safe when we aren't, or tells them exactly where we are so they can finish the job. Xenophobia is probably also why domes not barricades too. Give it a few years and some populist leadership, and that will be if not believed then followed rigidly by almost everyone, and not really questioned. Building radios inside is fine, but we dont do anything outside that draws attention. Not even passive listening. [Answer] Because every city they thinks it is the last city left The cities are far apart and, as the OP said, nobody from outside is allowed in. So, in every city the people have no clue that other cities could still exist. In such situation it is safe to assume that people have much more compelling things to do, rather than "wasting" rare and precious time, resources and energy to build a powerful enough antenna to contact other potential survivors. Many (short-sighted, but probably the majority) people would think that, even if another city existed, it would be no use for their survival, since it would be impossible to cross the land to trade resources. Other people would not rule out the possibility of other cities, but (as already stated in other answers) they would fear that the other cities, rather than helpful, would try to attack them and steal their resources. Add to the mix that the very first city to try to contact other cities through radio would find only silence and soon turn it off (in order to avoid waste of energy and resources for maintenance). In the end, in every city the cost-benefit of an antenna would be considered disadvantageous (particularly since I think that those cities wouldn't be aisles of plenty), so no city still has tried to contact other cities. [Answer] It's setting you up to be a target. There are still weapons that will home in on any active radio transmitter. While some hypothesize that there are safety precautions to prevent their attacking their own, no one knows what it is, and besides, it's known that several powers used them so you would need many such unknown precautions. Safer to not use them. Vastly safer. [Answer] ### Failure of repeaters Satellites and land based repeaters will fail. Some signals will be able to be passively reflected off satellites, but this is sub par compared to using active repeater. This will of course depend on where the satellites are. ### Long wave has costs While lower frequencies/ long wave as 'ground waves' that follow earth curvature will get signal thousands of km. But then the amount of information per unit time is low. A 30 kHz signal is approximately 1.5 kB/sec at best. 4 kB/s is plain telephone voice nominal allocated bandwidth. So one voice transmission per transmitter. To keep power consumption down the cities would want to use directional antennas, and unless you have dedicated antenna per nearby city, (which would be worth it if they have the resources). Then they could easily miss message from city B if they are aimed at city A. Omni directional transmitters wouldn't have aiming issues but the expense of operating them would could be too high. ### Distance A city could have AM/FM radio stations blasting out music/talk etc. Stuff like FM radio only goes 100 km or so, depending on transmitter power and height. So since there is no way any other city would hear, they don't really count for intercity communications. [Answer] # Faraday Cages Whatever material the domes are made of is opaque at radio wavelengths (even if they are transparent to visible light). Basically no other form of EM radiation has a range much beyond the horizon. --- On top of that landlines require maintenance, submarine cables even more so. The only form of long distance communication possible shall be [global warning](https://worldbuilding.stackexchange.com/a/126679/21222). [Answer] I have a few ideas. Any radio antenna outside the dome would eventually fall into disrepair with nobody going out to fix them and fail. Antennas inside the domes would be attenuated by the dome, which would presumably be built with metal parts to create a Faraday cage as well as just plenty of mass to diminish RF power. Increasing the power to break through could threaten people's health in the dome (as in turning the dome into a virtual microwave oven), interfere with vital equipment (medical equipment, internal radio networks, power distribution, etc.), and perhaps other issues. There is such a thing as ELF radio communications through the dirt and water. This requires very large antennas, a lot of power, and even then achieves very low data rates. I would think that given the overwhelming desire people have to communicate, and that this problem is not likely to sneak up on people, that plans would be made to maintain these systems even with considerable cost. Cutting people off will be difficult as ELF communications is well documented and anyone able to maintain a city sized dome should be able to build antennas and transceivers. It would take a lot in my mind to get people to abandon this as a means to communicate, even if it was at a data rate measured in bits per hour. --- After some thought on this and reading some of the other answers I believe it's just too easy to build an effective ground penetrating radio communications network. Ham radio operators are playing with this kind of equipment now. <https://en.wikipedia.org/wiki/2200-meter_band> I'm thinking that people would have to be afraid to transmit anything. I believe a better answer is a combination of what others came up with. Consider a non-biological virus that is attracted to RF energy. Transmitting anything attracts the virus to the source. The early attempts to fight the virus left behind long lasting RF generators in locations far from population centers that pump out RF noise like crazy. These would be powered by solar power, wind, hydro, nuclear batteries, or anything else that they could contrive that could keep going unattended for decades or even centuries. This keeps most, but not all, of the virus around these locations but makes radio communications difficult worldwide. Even that might not stop people from trying. And succeeding. There's no people outside the domes to pose a threat, right? So this isn't a case of a zombie apocalypse of people roaming about looking for domes that could provide clothing, shelter, and brains to eat. We have radio modulation systems that can operate below the noise floor. This makes the radio source difficult to track for intelligent humans, a mindless virus that is attracted to RF energy could be easily fooled with RF noisemakers while radio network can still communicate. Such communication schemes and frequencies are standardized and known by militaries, ham radio operators, airlines, and so on. Someone is gong to know how they work, and for people that don't these things are written down in books. A virus is not likely to stop people from communicating by radio. A non-biological virus attracted by RF energy isn't likely to either. Can this virus turn people into zombies? Radio wave seeking zombies? Can the RF seeking non-biological virus eat through the dome materials? That might scare people enough to stop trying. Maybe. [Answer] The vast quantity of radio receivers and transmitters on the planet would be decimated by the electromagnetic pulses caused by the detenation of multiple nuclear devices in the atmosphere. Similiarly so would computing devices,networks and all their support structure would be destroyed as well. The land based power sources would be damaged by EMP effects such very high amperage direct current being sent down power transmission line melting transformers triggering massive continental wide power disruptions. Just with that alone. No power to operate the devices no electronic communication whatsoever until such time the infrastructure gets rebuilt. Time frame involved several decades minimum to a century or two. The knowledge to reconstruct radio technology and power sources may be lost. Not all the survivors would be engineers or technicians. With regard to the ionosperic propagation of radio waves that is controlled by the Sun's radiation effect on the atmosphere and these effects vary depending on frequency and time of day. The time it would take for the infrastructure to rebuilt the radiation effects would long dissapated and as a result interference from fallout would be virtually non existant. [Answer] There are no technical reasons that would prevent communication, so you will have to create political ones. A useful subplot might include the consequences of illegal communications between cities. There was a book series "Silos" by Hugh Howey that included a similar theme. His cites were underground which restricted the communication possibilities in a way that might suit your needs. [Answer] Communications worked... for a while First of all, the main communication method would be internet, not radios. After all, to this day everyone is connected to the internet via different methods (incluind radio waves) but most/all of them at some point require a large wire bewteen two points, or a huge antenna communicating with a satellite. Now, humans had to lock themselves inside huge domes. Ok, they still have communications using all the methods they used before, after all the infrastructure is still there. But for this to keep working it requires maintenance, and after a few decades every communications installation and equipment outside the domes stopped working. Normal decay and zero preventive and corrective maintenance added to the fact of nature taking back its space outside the domes made all wires, antennas, data repeaters, etc. that were out there eventually fail. And who's gonna go to replace a cut wire if it means for them certain death in the worst-case scenario, and eternal exile in the best? [Answer] ## Somebody stole the ionosphere! For a few scattered domes to contact each other by radio, they need one of two things: satellite repeaters, or the ionosphere. I will assume the satellites have fallen victim to time, often being deployed low in the sky, or being cryptographically locked up with codes that are long since lost somewhere in the Contaminated Zone. That leaves the ionosphere ... where did it go? The ionosphere can be considered a little like an immense capacitor. It is hard to say if there are any "serious" proposals for tapping the vast energy that is undoubtedly there, but there are Tesla fans out there (I mean the real Tesla) who will write [long essays](https://www.quora.com/Can-electricity-be-harvested-from-ionosphere?share=1) about [Wardenclyffe Tower](https://en.wikipedia.org/wiki/Wardenclyffe_Tower) being some plan to capture the full energy of the entire ionosphere. Occasionally the impact of collapsing the potential on thunderstorms comes up as a separate alleged benefit. Let's not forget the fans of atmospheric heaters such as HAARP while we're at it. I think I would prefer to suggest tapping the ionosphere by some more recently invented means - using an intense laser system to create a pathway of ionized air, perhaps? If someone can do it, they have solved their full energy requirement, while causing a "[sudden ionospheric disturbance](https://en.wikipedia.org/wiki/Sudden_ionospheric_disturbance)" and loss of communications for everyone else. I admit, this is on the fringe of fringe, but there you have it. [Answer] The starting event of this is a geomagnetic flip of the poles. The time for the flip to occur is measured in hundreds of years. Typical scenario is that the poles split into smaller weaker poles that wander around for a few centuries then reconsolidated. The wanderings start decades before -- time to build the domes. population is determined by how much food can be grown. There is air exchange with the outside, but through sanitization methods. You will have a problem with domes overheating. Greenhouses run an air exchange per minute in summer to keep cool. Possible a double dome with the interior filled with soap suds to reduce heating. During this time, the earth has no decent magnetic field. Solar wind blasts straight into the atmosphere destroying the ozone layer and radically changing the characteristics of the ionosphere. I don't know that this would make radio impossible, or just erratic. Aurora would be world wide. Non hardened satellites would be destroyed by solar wind. Domed cities necessary or protection from UV as well as virus. UV may have caused the virus mutation. That said, it has to be a tough virus to withstand UV from being outside. Viruses generally don't do well outside a host. Your virus needs a non-human host in the outside world. Mice? Chickadees? You could also use a persistent bacteria such as anthrax that is viable in the soil for over a decade. You need a disease that has a non-trivial incubation time. Otherwise a city could have a secondary 'quarantine dome' where people would wait for X days before entering the main dome. (The word quarantine has the same roots as 40. The number of days ships had to wait in harbour in Venice before anyone could come to shore.) Bigger cities would have staged quarantines. You come into A. After 2 weeks of no sickness you move to B. Two more weeks you move to main. If the disease has a dormant spore form (anthrax) then people come in naked, shaved (yes there) and bleached. [Answer] Electrolytic capacitors present in many circuit boards have a short life span (~15-30 years). Once they are gone, the circuit no longer works. If you lost your industrial capacity, you will not able to build replacement parts and all your electronic devices will become useless. Electrolytic capacitors is the only practical alternative for high capacitance requirements. ]
[Question] [ This settings' world is united by a world religion that all countries pay homage to. It is controlled by a priesthood who, as well as fulfilling traditional religious roles, keeps the peace between nations to prevent destabilizing wars from breaking out. This religion has seven gods, with each of them representing various aspects of humanity that connect with each other. For example, the god of war represents honor, courage, battle prowess, etc. Above them is a creator god, who is viewed by the population as the mother of the seven gods as well as the world itself. All nations pay homage to the seven gods differently. Some worship all of them equally. Others hold one above the others, but still acknowledge them in some way. However, they do not worship the creator directly, despite recognizing it as the parent of the gods. The priesthood only pays homage to the creator deity. How or why would this be the case? [Answer] There's a longstanding tradition in religions of having an "outer mystery" and an "inner mystery." The gnostics were famous for this. Anyone is invited to learn about the outer mystery, and enjoy those rites, but only the privileged are inducted to learn the inner mysteries. These inner mysteries are subtle enough that even if you were told them, you wouldn't realize they were important until you were ready. As such, the seven gods may be seen as simply caricatures of the many faces of the one true god. To teach the citizens of the nations, it is effective to provide them with all seven faces, but once you enter the priesthood, you realize you only need one. As an example, a Chinese martial arts teacher may teach based on the 5 elements: water, wood, fire, earth, and metal. Much of natural phenomena can be described like this, and it is quite easy to understand. I can teach someone the rudiments of it in about 30 minutes. The Chinese also have a concept of yin and yang. These two polar opposites are constantly interplaying. Despite there being only two concepts, yin and yang, they are much harder to truly capture. I might give a good hearty try at trying to teach yin and yang. After a few weeks I might feel like I got some where. Deeper still is the concept of wuji - without a ridgepole or without bounds. Wuji is a concept of emptyness and nothingness. The concept of wuji is fundamental to much of the Daoist ideals which lie at the root of their philosophy and martial arts. I would not try to teach wuji. An understanding of it comes with time. If one understands wuji and several of its related concepts like wu wei, in 10 years time, it is a stellar accomplishment. As such, if the priesthood taught lessons along these lines, there is no point in teaching wuji to the citizens. They simply will not understand it, and it really would not help them in their daily lives. Teaching the 5 elements is far more valuable. Yin and yang may be useful. Let them merely play lip service to wuji. The priesthood, on the other hand, may live and breathe yin and yang, and be on a path to wuji. We see this in many walks of life where mastery is called for. For example, a jazz musician might teach chords, talking about V7 chords and diminished chords, and all that jazz. But when you look at what they really play, what they practice, the chords fall away. They just play music. It's one thing, and it's all they do. If you ask them what chords they played, they may be able to put together some chord progression for you. If you ask them what chords they will play, they'll just shrug and say "I'll play the music." [Answer] It might be a sign of prestige to be allowed to honor the creator god himself. The general hierarchy in this religion is: * Creator god supervising 7 gods * 7 gods supervising humans * Priests supervising general population * General population The priests need a justification to be in power, so they create a mirror image of the godly world in our human world. Of course they put themselves in the position of utmost power and claim to be the only humans the creator god deems worthy to even recognize. To defend their power against any worldly ruler wanting to create a new war or making the priest superflous, they create an artificial barrier for anyone wanting to interact with the creator god. They claim that only a priest, choosen by the Creator himself, can pray to and receive messages from the Creator. Eveyone else is simply ignored. You can even go one step further and let them punish any unworthy person who dares to bother the Creator with their insignificant problems. [Answer] Everyone could worship the god which is most relevant to their profession. Merchants pray to the god of commerce, artisans pray to the god of creativity, soldiers pray to the god of war, etc. And priests pray to the god of priesthood. The idea could be that a god will only recognize those with skills in a profession they are associated with and will only grant favors and insights related to their domain. So unless you have a deep knowledge of the holy scriptures and how to preach them to others, the god of priesthood won't hear your prayers. And unless you want something like insight for holding an inspiring sermon or pray for more donations to your temple, the god of priesthood won't be able to help you anyway. For example, imagine you are a priest of the god of war who is tasked with providing religious inspiration to an army. And you have a typical priests problem: The soldiers fall asleep during your sermons. If you ask the god of war for advise, he will only give you advise within the limited view of his domain, like "If anyone dares to yawn during your sermon, challenge them to a duel to the death" or "They will respect you more if you acquire honor in battle". The god of priesthood, on the other hand, might offer some more practical advise, like "don't hold sermons at 6 o'clock in the morning when everyone is still half sleeping" or "Address the everyday problems of soldiers, like blisters on your feet and missing your family". [Answer] This question is actually more realistic than you may think of, it is an exact scenario of Hinduism. In Hinduism, "Bramha" is considered as the creator god, however, he is never worshiped, out of the millions of temples in India dedicated to thousands of Gods, there is only a single temple, in a very small city named "Pushkar", where "Bramha" is worshiped. There are primary 2 stories, about why: 1. He became more involved in the created than in the creation, that he was cursed because of his unholiness and not performing his duties well. 2. To prove his supremacy over other gods, he cheated, then he was cursed because of being a cheater. In Both the cases, he was cursed to not to be worshiped by anyone else, other than a selected few. Another more logical reason could be – Lord Brahma (Creator) is exhausted energy. Lord Brahma`s work is done, he(the creation) is the past now. People care for the present and the future, not the past. This psychology of people makes Lord Brahma to be ignored. [Answer] Worshipping the mother goddess means dedicating your life to her, and renouncing worldly ties, including other ways of supporting yourself. This is something only priests and perhaps ascetics can do. One of their obligations is to serve and honor all her children, so they perform rituals to other gods on behalf of the laity. However, they themselves do not ask for the blessing the war god because they are not supposed to be warriors, nor likewise farmers, merchants, and so on. [Answer] The people are not worthy to worship the creator god. Only the priests are allowed to worship the creator god because only they can speak to the creator. If anyone else tries to speak to the creator through worship, the seven other gods will become jealous and strike the person dead and bring bad luck upon the harvest. For that reason, the priests have banned worship of the creator god. Worship of this god is blasphemy, and when someone is suspected of this crime, they are sacrificed to the gods before misfortune can come upon the populace. [Answer] The religion of the Seven Gods is useful to people in their daily lives. More importantly, understanding the Seven is a prerequisite to even begin to understand the true religion. Anyone who tried to comprehend or worship the Mother Goddess without fully coming to terms with the Seven Gods would be driven insane. So, the priests lead in the worship of the Seven, and teach it to the masses, and even teach it to their own initiates as the first stage in joining the priesthood, even though they don't actually believe in the reality of the Seven except as a pale shadow of the truth. In fact, even "they worship the Creator Goddess" is just an oversimplified summary of only the first of 23 inner levels of the true religion. But it's all anyone would know before deciding to become an initiate, and all a priest would explain to anyone outside. --- This is a relatively common idea in many religions, both historical and modern. According to Valentinian,1 learning the true Christ/Sophia nature is the second step to true worship—but if you haven't taken the first step and learned of the earthly Jesus first, you will at best fail to learn anything, and more likely be driven to insanity and maybe even head-aspodely death. According to the Church of Scientology, learning OT III (that's the one about Xenu and the DC-8 spaceships) is the most important step in going beyond the Wall of Fire that keeps you from being your true godlike self—but if you haven't thoroughly processed OT II first, upon hearing even the briefest sketch of OT III, you will catch pneumonia, and possibly suffer neurological damage and death.2 For a less extreme example, according to most schools of Taoism, trying to understand wuji without understanding yin-yang isn't going to make you cough yourself to death—but it is going to be a complete waste of your time, and make it harder for you to understand yin-yang. --- 1. Well, he probably didn't say this, but we didn't know that until the discovery of the Nag Hammadi codices. Most of the neo-gnostic, occult, etc. traditions that developed from the Renaissance to the 1940s were basing everything on what the Greco-Christian gnostics' enemies claimed the gnostics believed, especially Tertullian's attacks on Valentinian. 2. Apologies to anyone who died of pneumonia when I said "that's the one about Xenu and the DC-8 spaceships" above. [Answer] 1. Are we assuming that the motives of the priests are pure? If not, perhaps the priests "know" that the seven gods are false gods, and the creator goddess is the one true god. But they fear that if the people worship the creator goddess that she will give the people the same blessings and power that the priests get, and the priests want to be able to lord it over the people. 2. Somewhat like Philipp suggested, perhaps the people relate more to the god of their occupation or lifestyle. Soldiers worship the god of war because they understand a god of war and see a need for a god of war to favor them in battle. Farmers worship a god of the harvest because they understand a god of the harvest and need such a god to cause their crops to be plentiful. Etc. The priests are more intellectual than the common people and so worship a god of more "root causes". By that reasoning a few others might worship the creator goddess, like philosophers and artists, but they'd be a tiny minority. 3. The priests believe that the people are not worthy to worship the creator goddess and so they teach them a lower-level worship. Only they are sufficiently holy to worship the creator goddess. [Answer] ## Our God is a Tired God The act of creation exhausted the Creator God. So she formed the lesser Seven Gods to manage the various aspects of creation going forth. This probably exhausted her more. She now has only the patience and power to deal with a very select group of individuals. The clergy that worship her principally or entirely contains this select group of individuals, and are picked and promoted specifically for their suitability as acceptable worshipers of and burdens upon the Creator God. She ignores everyone else. This works well if the gods have explicit effects upon the world and worshipers, including but not necessarily limited to blessings. Because in this case the Seven Gods may bestow blessings and other things upon their worshipers, whereas no one, except maybe the priests, ever receive anything from the Creator God. Therefore, most people have no benefit in her worship, and so duly prioritize the worship of the Seven Gods, especially those of immediate relevance to their needs and lifestyle. However this can probably still be made to work in a world where there are not explicitly divine acts. In our own world we know that many people in many cultures had (and have) no issues with focusing on one or two gods out of an entire pantheon, including pantheons with Creators or precursor gods (Chronos for the Greeks, for example). Sailors may worships gods of the sea not because they are the most powerful god, nor the original god, but solely because they are the most (immediately) relevant god. Bonus possibility: One or more of the Seven gods, or various groups of mortals, may actively seek to capitalize on the Creator God's diminution, perhaps even to go so far as to seek to usurp the Creator God's mantle. Her worshipers may actively seek to thwart such efforts, actively encouraging the non-worship of the Creator God so as to limit knowledge of, interest in, and potential access to her. [Answer] # Colonialism and Syncretism One possible explanation is colonialism. Maybe the priesthood is originally from a monotheistic culture that conquered a polytheistic culture. While you might assume that priests in such a situation would violently suppress the polytheistic religion, that's not universal - for example, during the Christianization of Europe, priests and missionaries instead attempted as much as possible to assimilate the existing religious beliefs into Christianity, in order to make conversion more palatable. This is known as syncretism, and is the reason why we associate a Celtic fertility festival with the resurrection of Jesus, and why myths about Odin going out on a hunt during winter fused with a celebration of the birth of Jesus and the veneration of a charitable Christian historical figure. Perhaps the original polytheistic belief system had a "lord of the gods" figure like Zeus, Odin, etc, and the priests decided to associate that figure with their own monotheistic deity, and push the viewpoint that the other gods aren't technically gods, but rather powerful servants of a single god (more like archangels in Christian belief). However, they don't want to actively crack down on worship of the lesser gods because it would cause unrest and make people less receptive to what the priests tell them about the overdeity. [Answer] I have 2 ideas for this: 1. Possibly a very small group (5-50) of "high priests" are considered equals to the 7 gods below the creator god, & as such only worship the creator god as they are considered equals to the other gods. While lower priests are considered part of a high priests collective entity & as such are on the same level as the gods below the creator god. With the a high priest considered as the base of this entity consisting of many putting them incharge of it. 2. If this church fulfils a role similar to the united nations in this world. Possibly the creator god is worshipped by the priesthood in order to maintain neutrality. As to avoid having nations that worship the 7 other gods in a closer way as the church does be considered more favored by other nations, decreasing many nations trust in the church. [Answer] The creator God is All-Time. It's a complex process to connect with All-Time. When handled inappropriately, as novices usually do, the side effects are difficult to handle at best, and indeterminate at worst (because they disappear into time, so it's hard to really say what the worst ((best??)) side effects may be). Long ago (or possibly yesterday), some really intuitive folks (eventually become the priests) decided to limit access to All-Time. They created a system to provide stability for the novices. This system happens to contain this world which easily mathematically has Still-Time. Still-Time, contains repeating years months, seasons, etc. They also have seven days in a week, which the novices over time cheerfully anthropomorphized into what became their seven gods, based upon themselves. This system gives the novices opportunity to understand Still-Time in order to someday advance to other Times, which also contain sects of the priests who worship the Creator. Most novices have even forgotten that they are there trying to understand Still-Time, much less All-Time. With time, luck and/or effort, they remember and are given the opportunity to join the priesthood and also worship All-Time. ]
[Question] [ This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. I'm working with the idea of creating a sun made out of pure gold. Of course, this would be completely man-made. Why would anyone want to do this? Because I want a cool concept like that in my story! :) First, you start small, combining thousands of pounds of gold. And you continue to add more and more gold. And you end up with a small gold planet. How marvelous. But we're not done! We continue to add more and more mass by continuing to add more and more gold. Eventually, we'll reach a point where the mass is so great that the pure gold atoms begin to undergo nuclear fusion within the core of this massive gold planet. And thus, a star is born! But, I have no idea what elements would be created from this. After doing some [basic research](https://en.wikipedia.org/wiki/Isotopes_of_gold), I've learned that the only known stable isotope of gold is 197Au, so that should be a good starting point for people answering this question. # What elements are created during the initial nuclear fusion state of a gold star? I also looked into the [nuclear fusion process](https://en.wikipedia.org/wiki/Nuclear_fusion), but I have learned that it is a very complex process that I simply can't learn in the amount of time I have. [Answer] Unfortunately, no matter how much pure gold you add to your mass, you will never end up with a star. The reason for this is that fusing gold is an endothermic process, meaning that it requires energy, rather than releasing it. In fact, all elements with an atomic mass greater than or equal to that of iron consume energy upon fusing, rather than releasing it, as all atoms which are smaller than iron do. The reasons for this are complex and have to do with the [binding energy](https://en.wikipedia.org/wiki/Nuclear_binding_energy) of atoms. The binding energy of an atom is always positive (as if it were not, the hypothetical atom in question would spontaneously fly apart as soon as it formed) and increases with the size of the atom. Up to a certain point, the binding energy of an atom created by fusing two smaller atoms is greater than the sum of the binding energy of the component atoms. For example, when combining two atoms of Hydrogen into one atom of Helium, the binding energy of the Helium is greater than the total binding energy of the two Hydrogens. The net potential energy of the system has now decreased (as it would take more energy to separate the new atom into its component parts than it would have for the previous atoms), and thus energy is released (generally as heat). However, as the size of atoms increases, the binding energy begins to increase by smaller and smaller steps, until one reaches the tipping point. When one fuses, say, an Iron atom and a Helium atom, the result is a single atom with a binding energy lower than the sum of the binding energy of the two original atoms. Thus, we have increased potential energy and actually had to consume energy from outside the system, making the reaction endothermic. As Gold is a much, much larger atom than Iron, it is incapable of fusing exothermically, and thus your star will never get off the ground. If you add sufficient quantities of gold at a quick enough rate, it may release energy via contraction, but it will be massively dimmer and shorter-lived than an equivalently massed star. In the end, if you just continuously add gold to your mass, you'll end up with a black hole before you ever get a star. [Answer] This star would not fuse gold. Fusion reactions producing elements beyond zinc-60 [are not energetically favorable](https://astronomy.stackexchange.com/a/21288/2153); they are endothermic, and so consume energy. Several elements heavier than iron are formed through this fusion chain and subsequent decay ([cobalt, nickel, copper and zinc](https://www.forbes.com/sites/startswithabang/2017/09/02/ask-ethan-can-normal-stars-make-elements-heavier-and-less-stable-than-iron/#44dd9677668e)), but these are unstable and decay back to iron, meaning that iron is essentially the heaviest stable element that can be formed in stars or involved in significant fusion. Two exotic processes - the [r-process](https://en.wikipedia.org/wiki/R-process) and the [s-process](https://en.wikipedia.org/wiki/S-process) - can fuse heavier elements (see [Burbidge et al. 1957](https://authors.library.caltech.edu/45747/1/BURrmp57.pdf), [Clayton et al. 1961](https://ui.adsabs.harvard.edu/abs/1961AnPhy..12..331C/abstract)). These involve a neutron being captured by a so-called seed nucleus; repeated neutron capture produces heavier and heavier nuclei, and it is not unrealistic to think that gold could be involved. However, these processes need neutron sources; even the slower s-process requires neutron densities of $10^{13}$ neutrons per cubic centimeter ([Lugaro et al. 2016](https://iopscience.iop.org/article/10.1088/1742-6596/703/1/012003/pdf)); the r-process may require neutron densities on the order of $10^{24}$ neutrons per cubic centimeter (see Burbidge et al.). As the star is made purely of gold, there is no existing neutron source (e.g. the fusion of carbon or neon nuclei with alpha particles), and therefore neither process can proceed. [Answer] Not really a star, but it could still shine. As others have said, no fusion would happen. However, depending up how you add the gold, it would fall until it hit the current mass. For example, meteors impact the earth at speeds greater than escape velocity (at least when they impact the upper atmosphere) Earth escape velocity is about 11.2 km/s. Solar escape velocity is about 617.9 km/s. Considering the well known 0.5 M\V^2 relations for kinetic energy, solar impacts are going to be 3000 times as energetic as earth impact (which are already white hot) If you consider solar asteroid bombardment, they are going to be well over white hot after impact. Given the mass of this "sun", it is going to glow for a very long time. Historically, gravitational collapse of the sun was considered as a possibility for the source of the sun's heat. Even if you carefully set the newly arrived gold on the surface, it is still going to compress under gravity and release enough energy to glow for a long time. [Answer] As others have said, you can't have self-sustained fusion with gold. But is there a chance you might make fission work? If you look at all the atoms, the light ones can give off energy by fusion. Like hydrogen combining to make helium (sometimes a little bigger atoms, but still on the small side, getting bigger. This is what occurs in the sun or in hydrogen bombs. In contrast, the heavy elements can give off energy by FISSION. Heavy atoms splitting into smaller ones. The best example here is uranium or plutonium in fission bombs or reactors. In the middle, you have Fe. It's basically dead. Can't get energy from fission or fusion of iron. See graph: <https://en.wikipedia.org/wiki/Nuclear_binding_energy#/media/File:Binding_energy_curve_-_common_isotopes.svg> Now gold is to the heavier side of iron. So it's not going to do fusion. It might do FISSION though. I totally haven't thought this through...but on a worldbuilding site with sufficient handwaving (with a bias to making the idea work), perhaps you could imagine some massively huge/dense bunch of gold, where neutrons can build up and be moderated/absorbed/cause fission. Given the huge size, leakage would be low, so even a very crappy reaction might become self-sustaining. Perhaps some trace isotopes that emit neutrons (or perhaps seeding with a minor amount of uranium or other neutron sources), then perhaps you could get a self-sustaining fission reaction where enough neutrons are produced from gold fission to sustain the reaction. Gravity would tend to keep the stuff from flying apart (same as fusion). And you end up with some sort of equilibrium of gravity/nuclear reaction in terms of the stuff hanging out as a star (not blowing up, not shutting down). If this were possible, you'd have a shining fission star, not a fusion star. Maybe not quite as bright as a fusion star. But still a ball of very hellish energy. In terms of the atoms that would result, you get a distribution of smaller elements. With uranium, this tends to be bimodal. Centered at half of the nuclear mass, but with peaks to either side. It's called the Mae West curve. See here: <https://idahospudsblog.blogspot.com/2013/10/some-odd-quirks-that-nuclear-reactors.html> As you can see, the two peaks are actually about 20 mass units below/above the half-weight of U-235. I'm not sure about gold, but it seems reasonable to expect some similar bimodal distribution centered around half the nuclear mass. If not, then a normal distribution centered around the middle. I sort of think bimodal is more likely though. Has to do with the jellium\ model of how fissioning atoms split. If we assume something similar for Au-197 (stable isotope of Au), then we could assume about 100 for the midpoint. So something around 80 and 120 for the two peaks of the Mae West curve. Might be a little tighter like 85 and 115, given gold is smaller than uranium. Stable nuclide atoms in that weight are, respectively rubidium and indium. Of course, you are going to get a soup of atoms and nuclides of atoms. Some of these may react a little further in various fashion to move up/down slightly in the atomic number. But the big picture: lots of rubidium and stuff close to it. And lots of indium and stuff close to it. \Not joking that's what it's called...nukes love their little names...look up "barns" for instance. [Answer] This question asks for hard science.* All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. Nothing will happen until you get enough gold to overcome electron degeneracy pressure. Then your gold fuses into one ginormous nucleus and the protons capture the electrons. [Answer] This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. As noted, Iron is at the end of the curve of binding energy, and when the fusion of heavier elements ends with iron, you cease the fusion reaction. The core "goes out" and the massive gravitational energy of the star draws everything back towards the center (up to now, the energy of the nuclear fusion reactions have been "pushing back" against the gravitational collapse of the star). The rapid infalling of matter onto the iron core creates the implosive energy that results in a Type II Supernova and incidentally is where all the elements heavier than iron are produced in the universe, including gold. As noted, simply dumping more and more of any element into one place will simply create a black hole (possibly you might stop at an intermediate step like a neutron star if you carefully control the amount of matter you add and stop at the correct time). Since our understanding of Neutron stars is incomplete, there is a possibility that the layer of atoms on the surface of the neutron star might be transmuted into something besides gold or neutronium, but this is only a guess. The only "real" (for some versions of real) way to do something like this would be to create a gold sphere the size of the core of a star and teleport it in to replace the existing core. The stellar collapse will create a Type II supernova, but given the extreme energies involved, the actual material of the core really makes no difference at that point, the implosion will tear everything apart and fuse it into all the heavier elements. If there is any way to determine if there is a gold core rather than an iron one, it would probably take a careful analysis of the ratios of various elements created in the supernova explosion (although I have no idea of how you would mathematically calculate the elemental ratios of a non iron supernova core explosion). As a story element, this could be the rather subtle indicator of the presence of super science or an advanced alien race, who are looking to mine the stellar debris for elements and might want a larger proportion of transuranic elements (they need to move fast before they decay). [Answer] This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. You would use all the gold as gravitational mass to produce fusion of hydrogen in the center. Stars burn by fusing light elements; hydrogen at first, then helium and so on. As has been pointed out in other answers, once you get to iron you do not get energy back from fusing elements. Heavy ones like gold are only created in supernovas that have loads of excess energy which is drunk up by the fusion of heavy elements. A regular fusion star has so much stuff that it compresses the stuff in the middle until fusion starts. Most of that stuff is hydrogen and light elements. But you happen to have a lot of gold. In the center of your gold star, you leave some hydrogen or helium-4 or muons or other things that like to do fusion. The mass of the gold compresses the center until fusion starts. Because it is gold you don't need as much of it to achieve the needed central compression so your gold star is nice and small; smaller than a star for sure. The heat of the fusion melts the gold, of course, but molten gold is also awesome. The gold star is heated by the fusion to white hot and so glows with the same frequency as a star. You might want to build in a way to refill the hydrogen center. --- @Muuski in the comments! OK. Here is a chart of hydrogen phases <https://www.pnas.org/content/107/29/12743> [![hydrogen phases](https://i.stack.imgur.com/SpJV6.jpg)](https://i.stack.imgur.com/SpJV6.jpg) If there is enough pressure the hydrogen remains a liquid metal. If the pressure comes down it changes to a plasma. In the center of the gold star, the pressure is high so you have metallic hydrogen. The adjacent gold would probably be solid too; it is also under pressure. But gold is an excellent thermal conductor, and so at some distance from the core, the gold would go through its various phases until the exterior would be gold plasma. We are for the moment handwaving away objections about how the hydrogen core stays put in the center. [Answer] # A gold star may be possible, with a fission-fusion reaction. The other answers are correct, gold is heavier than iron, so fusing those atoms will consume more energy than it releases. The extra energy gets encapsulated in the binding energy holding the nucleus together. As far as I can tell, it's not known what the product of an AU + AU fusion is. But, like all elements heavier than Lawrencium (and not in the Island of Stability), it will probably produce a very unstable element with a very short (less than 1 second) half-life. And this is the key point here. Let's call this element Doublegoldium. This means that the Doublegoldium atoms will actually release a lot of the energy it sucked up in the fusion process. It will release this energy as radioactive decay, and these decay products may trigger fission in each other via a nuclear reaction. Or, Doublegoldium may even just directly undergo "spontaneous" fission. In fact, it is possible that the fission will release more energy than the fusion absorbed. The question is whether this process can complete a chain reaction of ``` heat -> fusion -> unstable element -> fission -> heat ``` where the heat generated is greater than the heat absorbed. How much extra heat will determine how hot the star is. A fission-fusion star would probably be unique in the universe. All in all, nobody truly knows what would happen. Nobody has ever tried to fuse gold atoms, and decay of unstable elements can be very complex. But it is possible. ]
[Question] [ I've got an idea about boarding parties on spaceships but it's based on the continued existence of infantry, and infantry weapons that are designed to function in an open-system environment. The question is in a world where: 1. orbital bombardment is a thing and in fact a common first resort weapon. 2. environmental damage caused by bombardment can be mitigated to the point where it's just not a consideration. and 3. the vast majority of primary industry and manufacturing are in orbit so on-planet resources and infrastructure are not important targets. Is there actually a reason to have large-scale armies that can invade worlds? There will always be reasons to have small units for assassinations, extractions, and espionage/sabotage missions on planet but that's a very different skill set and weapons philosophy to massed infantry which is what I'm interested in. Edit: just so it's clear any group that is using orbital kinetic bombardment as a first strike weapon does Not care about civilians, neither casualties or survivors, at all. Sorry I thought that would be obvious. Edit 2: MichaelK's quite right I haven't given enough context for really concise answers, there's a lot of good material here anyway but I like clarity too so background and hopefully a clarification of the question as well: In the universe I'm working on humanity started to spread to the stars with FTL starships centuries ago and has colonised a reasonably large number of star systems, with heavy colonisation out to 15 Light-years and rumours of colonies as far away as [Canopus](https://en.wikipedia.org/wiki/Canopus), FTL is limited and does not extend to direct communications. Conflict between/within human colonies is rare but tends to be catastrophic, there are rules of war and a "stellar navy" of sorts that can enforce some penalties but the reality of the war courts is that living victims get results and you're pissing into the wind trying to get convictions without them. This reality leads to really devastating bloodshed when a conflict "goes hot" because neither side really wants to leave anyone standing on the other side, it's in their interests not to. So orbital bombardment is a weapon that is actually useful because of it's indiscriminate nature. Planets play less and less of a role in civilisation the further you go from Earth, orbital factories take advantage of orbital materials to create goods that largely spend their consumer lifetime in space. Planets make good living space for populations because artificial gravity is still expensive and/or awkward, and those who stay on-planet for work contribute to co-ordination and logistics within light-speed communications range. Planets can also be used to grow luxury real foods like meat and cereals that can't easily be grown in space. Almost all infrastructure is in orbit, including power for Arco-cities on planet. Now on a planet using high-power kinetic weapons isn't much of an issue, you can get away with stray rounds etc... they'll come down somewhere, in space you don't have that option, a stray round powerful enough to punch through armour based on astro-engineering hardsuits that protect from micro-meteors can punch through civilian structural members potentially trashing the target and the boarding crew. From my point of view if the only troops who see regular action are in boarding actions where those risks are a constant consideration, and it's been like that for generations, then people being people they'd come up with projectile or energy weapons that function there but if planetary infantry are still a big thing then boarding parties wouldn't get the same attention and would have to go a different route. So is massed planetary infantry a working model when trashing everything at the bottom of a gravity well is not only feasible but also in some ways preferable? [Answer] I am going to assume you're wanting some plausible reasons for why a military would continue using ground forces after you have the equivalent space fire-power of, say, Imperial Star Destroyers. This assumes your invaders aren't just mindless monsters hell-bent on destroying the galaxy. While such creatures make great monster-movie tropes, an intelligent species would have (we hope) some reason to attack beyond just destruction of the planet and all on it. If that's not true; if their purpose is truly to wipe all life from the surface of the planet, then ground troops serve no purpose. Bomb the planet into a uniform-height dust bowl and move on to the next. The terraform crew can follow and do whatever they do. ## Other Resources You mention that environmental damage isn't a factor. Okay. But there are other resources that may not be merely environmental. * People (if life is precious) * Endangered species * Historical and cultural artifacts * Art (that isn't purely electronic) * Disruption to trade (raw materials go up to space station to be manufactured...) * Food production (is likely cheaper on the ground than in space) ## Psychological Maybe you don't want to instill terror in the hearts of all people, everywhere. Bombing from space might serve better as a a worst-case scenario to hold over your enemies' heads, rather than a daily fact of war. See also [Nuclear Deterrence](https://en.wikipedia.org/wiki/Deterrence_theory). ## Collateral damage Maybe there are citizens of your empire that you prefer to keep alive. Diplomats, spies, trade representatives, non-combatants, whatever. There's a cost for destroying them, and sometimes that cost isn't worth paying. Ground troops can evacuate key personnel from the surface rather than destroy them. ## Hearts and minds If you bombard the planet into rubble, you destroy any chance of the citizens ever becoming trustworthy, reliable, members of your empire. Any survivors out there in the galaxy will turn the destruction of their world into a reason to rise up in rebellion. That may mean guerrilla warfare. Or peaceful protests. Or open rebellion from other worlds. Remember the Alamo. Martyrs are powerful things; making an entire planet a martyr could have devastating consequences later. So ground troops let you have more precision on where you strike and to what degree you destroy things. ## Fear A horror author once told me something like "fear isn't the threat of your own death, but the threat of not being able to prevent your friends' deaths." If the entire planet gets converted to rubble, that's an existential terror that, like global warming or the risk of eventual meteor impacts, doesn't register very high for most people. But send in an army and suddenly the people not currently getting shot at have something to fear. Maybe they'll fear your army enough to surrender before shots are fired. Or at least before all life is laid waste. [Answer] # War is not about smashing things If all you wanted to do was to blow thy enemies to tiny bits in thy mercy, then orbital bombardment will do the job without the need for infantry, that is correct. But war is not about that. Smashing things to tiny bits is but a means to an end. The end is control. Control over resources; over people; over transport lanes; over the enemy's military so they do not try the blowing-to-bits trick on you. Granted, blowing the enemy to bits can achieve some level of control: if the enemy's military is in tiny bits, then you have control over it... after a fashion; if the enemy themselves are in tiny bits then you have control over the enemy... sort of; if all of the enemy's resources are in tiny bits, well, at least they do not have any control over them, putting their level control in parity with own. However, that is not a satisfactory win, now is it. You spent all that money, all that effort, all those weapons and lives of your soldiers, only for your reward to be a big pile of tiny bits. That could be done a whole heck of a lot better, I think you agree. Hence, infantry. Infantry are the ones that actually go down there and establish the fact that you are now in control, and not just over tiny bits but over people, over factories, mines, refineries, nuclear power plants (geez, are you not glad that you did not put a relativistic kinetic railgun dart into that) and similar such things. --- So, to summarize: orbital bombardment is the big fist that smashes stuff to tiny bits and gets you a win. But infantry is what gets you a useful and gainful win. [Answer] > > Is there actually a reason to have large-scale armies that can invade worlds? > > > Armies are require to police your populace, protect assets, and take things so why not train them in planetary invasion as well? 1. The attackers don't value the lives of soldiers. Invade away. "Grunts die, its what they do" 2. "Training exercise" to give your armies a blooding, test invasion before a mission critical world, test new equipment in a fight. 3. Hardened defenses scattered miles deep under the crust of a hive world, requiring specialized equipment to drill to a hive comb, and troops to go down the rabbit hole. 4. World hopping, moving armies from one world to another, this planet could be an island on the path to a final destination, and the cost in lives might not be that high verse the cost in time for your ships. Drop and go. 5. Bureaucracy, army is going to do it cause the army is going to do it. Hoorah? 6. Availability the army may have ships available while the the orbital bombardment armada is needed else where. 7. Glory, propaganda. Boots on the ground and flag waving can make impressive pictures of success. 8. Butchery over starvation, a ground invasion is preferable if you can't feed your people. A swarming species could use this as a practice to cope with overpopulation. A shrewd government could use this to force a people to invade another's for food. Its common accepted theory that normally people don't want war, this could be a good means. 9. Auxiliaries are persons other than citizens that fight for your people in hopes of citizenship. A form of "required" progression might be to fight for the empire in a certain number of battles. Added bonus the soldiers you drop become the colonists after, they are literally fighting for their future home. 10. Rogue army, a governor of a nearby world not in control of combat vessels could levy an army and civilian ships very quickly. 11. Anti-ship weapons render large orbital bombardment ships neutralized. Does the world have an answer for drop ships in the millions though? 12. Genetherapy of a society, send the most undesirable elements of your civilization on a suicide invasion/redemption by fire. 13. Unique world, how do your bombardment weapons work on a water planet/water species? Not well I might think. The way I look at it is Numbers is an advantage and a problem How do these advantages and problems compel a government of any type to send millions or billions to their deaths? The most common thread is that soldiers lives are cheap, and do no require much consideration. If soldiers lives are expensive, and there are other options then soldiers will never be used. [Answer] Force Fields Planetary force fields. You think your tiny spaceship has shields? This is a planet without any need to optimise for mass or heat. The power of this shield would take 100 destroyers 100s of hours to pound through. And you know what else planets have defence batteries. Gun arrays larger than your ship connected to power grids that normally power cities. They will turn your destroyers parked to fire at full power to slag in seconds. Good thing we got infantry. Piloted ships can dodge heavy fire and move through enemy shields using expensive energy intensive shield phase slip technology only viable for ships. Once we get our boys on the ground it's a different game. Secure a shield facility, pull the switch and the bad guys surrender or get to know what big mama has ready for them. [Answer] Orbital bombardment would probably not be a first method or approach even if you didn't care about civilians. You stated that they wouldn't need to worry about blowing up factories because they're in space, but if this is trues then why bomb planets at all? There has to be something significant on the planet in order to give an incentive for orbital bombardment, and if there is something significant you might want to capture it instead of destroy it. If the planet didn't matter, no one would bother bomb it, and if it did matter, people would send soldiers to steal it. If war crimes are no longer an issue in your world, then attacking forces may instead use other tactics such as deploying chemical weapons to kill most of their enemies and then sending in an army to capture valuable resources and infrastructure. Even if there was no need to fight for planets, there would still be a need to fight for the alternative orbital infrastructure. This might not lead to massive armies, but boarding and capturing a sizable space stations or very large ships would probably require a lot of ground troops (or androids). In this scenario, soldiers may also opt for melee weapons for fear of stray projectiles causing holes/breeches, or in other ways damaging the space station. It also may be better to not leave evidence of orbital bombardment. If the bombing could be traced back to a particular individual or group, then that person could suffer legal or political consequences. Also leaving evidence of a bombing could lead to retaliation from your enemies. For these reasons it might be better to send in an army to force relocation. [Answer] # What is the purpose of the war? If your aim is just to burn everything and leave the planet a charred husk then troops aren't required, but for anything else, someone will have to get dirt on their boots. One of the aims of the war is apparently total annihilation of the opposing population, that's a tactical consideration not a political one, why did the war start in the first place? If there's anything you want to secure then you're going to need ground troops, whether a facility, technology, or otherwise, you'll have to put troops on the ground. # How much infrastructure do you want to maintain? Is a breathable atmosphere one of your requirements? While a war of total annihilation is possible with orbital bombardment, the chances are that by the time everyone is dead, so is everything else, and the planet may not be habitable without appropriate [PPE](http://www.hse.gov.uk/toolbox/ppe.htm) for several decades. Sufficient damage to eliminate resistance followed by ground based clean up crews would be a better option to leave you with a habitable planet. # Current experience Current conflicts in the Near East are showing that air power alone does not win wars. Ultimately you will need to have boots on the ground. Are you going to declare victory and send down civilians after a bombardment? Unlikely, it's going to be troops. [Answer] One answer is already shown in `The Empire Strikes Back`. Although Vader may have some motive towards getting the Falcon, the main objective is to destroy the Rebel alliance (Skywalker really isn't that great of a Jedi at that time). They're there, all in one spot, and surrounded by a massive fleet. A single Star Destroyer, although its name most probably doesn't mean it's meant to destroy a star, might very well just blow the better half of Hoth to smitereens from the orbit, rebels included. There's a dozen of them in orbit. You have to wonder why they still send infantry and care to fight rebels in snow speeders when they could just have it the easy way. The question states that environmental damage from orbital bombardement can be sufficiently mitigated so it is not a problem. This suggests technology is well enough advanced to provide something like "shields" as per the common trope (and as shown in the above movie). The second, and equally important reason is that you don't want to destroy either the planet or the enemy facilities. You want both the planet and the facilities intact and usable without much of a need to repair infrastructure. All you really want is to remove the superfluous humans that presently occupy your new possession. Infantry can provide that, orbital bombardement doesn't. [Answer] The real issue - whether your infantry is a Greek Phalanx or a horde of Warhammer 40K grunts - lies in defining the strategic objective is, in conducting the war. If your opponent holds a planet that is clearly vulnerable to orbital bombardment, he values it for some reason. General principles dictate that one possible objective is to deprive him of things he values, or to offer the threat of loss. If the population and/or certain assets based on the planet are valued, a planetary bombardment that destroys that value, makes no sense unless whatever utility you would gain by holding them yourself, is outweighed by the 'message' you send by destroying them. A planet reduced to its constituent raw materials is considerably less economically valuable than a functioning outpost - at least, your opponent thinks so. Heinlein covered this in considerable detail. Warfare is controlled, constrained, and ideally surgically-applied violence, employed to achieve a political and strategic end. In a future where orbital bombardment constitutes 'normalcy' in warfare, infantry constitutes irregular warfare, whether it's a bunch of Mechanized Infantry a la Starship Troopers busting up an outpost of the "Skinnies" , or a bunch of punkass kids trying to obtain a very specific item via a reconnaissance-in-force a la Star Wars Episode VII. If the aim is galaxy-wide xenocide of a species who is so alien that their calculus of 'value' is meaningless to you, sure, maybe a swathe of orbitally-bombarded planets is precisely the answer, and you don't see any reason in leaving room for negotiation, because you don't want to defeat the emeny, you want to exterminate them, but in many other scenarios, the strategic objective will always represent a cost-benefit analysis. What do you want? How much will it cost you to get it? If deployment of whatever constitutes 'irregular forces' achieves it with less cost, effort, risk or whatever you want to minimize, then a prudent general would use them. [Answer] There will always be infantry. Its shape will just change, as it always did. Think about it, infantry has successively with society towards more training and specialisation. During the last century, a lot of contries have shifted from conscription to a professional army in which every soldier has a very specific role for which their have been heavily trained. Given that, speculating about what infantry would look like in your future-tech settingh has a straight answer : Robots. With the development of AI and engineering, your setting's factions should be able to make robots that are precisely designed for precise tactics with AI developed for that exact purpose. That leads you to all kinds, sizes, equipments and behaviours aimed at given tasks or strategies. Regarding the precise issue in your question, you can easily imagine modules that are thrown by warships at ennemy ships so that they nail through their hulls and infest them with dozens/hundreds/thousands of modular/self sufficient and self conscious/hive minded robots. If successful, such a tactic would allow a faction to take control of another ship without destroying it, same thing with a planet. [Answer] Big Infantry is needed to control a lot of ground, and the planet is not going to be worthless. The relationship between an Orbital station and the planet is likely going to end up an awful lot like the relationship between Major cities and rural areas in the current day. When people think of the United States, it's the cities that come to mind. People think of New York, LA, or San Francisco. That's the first image. People don't often go to Kansas or Nebraska and the enormous farmlands there. They don't think of the mining operations in Colorado, or the fossil fuels in Texas and Oklahoma. However if Kansas and Nebraska go away, New York starves in a handful of days. Without Texas, transport in LA becomes a helluvalot more expensive. Your planets will provide the raw material basis to feed the Orbital station. There is not going to be anything up in that station that doesn't get there from a long way away. Entropy says that your closed ecology may be able to last a while, but not forever. Your stuff will have to come from somewhere and planetside is the most logical place to get it. So why an infantry that goes planetside? If you can send troops to control the raw material resources, you render the orbital station helpless. It's a just a siege that's shaped a little differently. Orbital station is not going to want to totally bombard the surface, because that could destroy the farms, mines and such along with the infrastructure that gets the needed stuff to the station. If they blast the spaceport that foodstuff lifts off from, they starve. Finally, if you wipe the surface of a planet, you become the genocidal maniac. Nobody want's to be that guy (it's been brought up in other answers and it absolutely bears repeating). Always remember, War is about control, not about destruction. [Answer] > > the vast majority of primary industry and manufacturing are in orbit > so on-planet resources and infrastructure are not important targets. > > > Manufacturing implies resources of some kind, and if they aren't being shipped from the planet, I assume they're being mined from asteroids or moons. With your bombardment technology, presumably you could blow up an asteroid; but then you lose its resources, and what's the point of that? Plus it would be really convenient to capture any mining equipment intact. So you need infantry to take control of the asteroids. If you're fighting in the tunnels of an asteroid mine, most stray rifle shots will simply hit rock; no big deal, so you don't need extra-low-powered weapons. And if your asteroid has a 50 (or 500) mile diameter, you can't just send in your small specialized unit. You need the numbers that only infantry can provide. It makes sense that the defensive infantry would be there to protect the high-valued target - they'd be useless on the planet if the attackers are just going to kill everything. [Answer] Some of your premises are...unlikely. This is about fiction so you can set it up however you, but if you are going for any sort of realism, remember that gravity is an advantage for a lot of things, as is having the foundation beneath you. In short, it is unlikely that all manufacturing would move to space regardless of technology level or even if the atmosphere was hostile. Second, while less significant to your question, going to bombardment as a first strike does NOT immediately indicate a disregard for civilian casualties. Unless there is some affirmative reason not too, it is standard policy in most modern militaries to start with either artillery or air strikes and then follow up with infantry. Of course, I am talking about strikes on legitimate military targets rather than civilian cities, but for the most part the military targets will be at least somewhat separated from the civilian ones for a variety of practical reasons. Your main forces feed into your special forces. AS others have discussed, especially MichaelK's excellent answer, infantry achieves things that bombardment cannot. I won't go into detail since they already did other than to second that point. But even if you assume that large armies are largely useless in your world, they will still exist. You said, "There will always be reasons to have small units for assassinations, extractions, and espionage/sabotage missions on planet..." But you derive those units from your main army. If you really needed those, you would still maintain a reasonably large army just so you had somewhere to vet and select your special troops from. Major League Baseball needs the Minor Leagues to exist for instance and the NFL needs college football to exist which in turn needs high school football. If you really need those special small units, you will subsidize a relatively sizable main army to select them from. [Answer] Defences can be hardened or hidden vs orbital bombardment At the onset of war, the defending planet will get devastated from orbital bombardment. Because this is a common occurrence, it means that defenders would likely have people in bunkers or hidden locations for a counter attack. The devastation and rubble of the aftermath makes it hard to search for their locations, or the location of any hostages or POWs who might still be alive. Humans with flexible thinking are good resources to ferret out human resistance For the purpose of going thru complex terrain that cannot be scanned from orbit, the attackers have to land a moderately sized force in a land invasion. These have to be people and not drones (except in supporting roles) because machines aren't good at searching out people. In addition, the soldiers used get to loot any leftover baubles so they get many volunteers for this position, especially from the poorer populace. Undersea or underground bases cannot be easily attacked remotely Armies can follow human transportation links such as tunnels, elevators etc. to chase after retreating defenders and wipe them out before mediators can stop the war. Trying to solve the problem with more bombs might not work, and would attract attention from the stellar navy incoming to mediate the conflict. [Answer] If you want to destroy things, you don't need infantry - you use artillery, tanks, air strikes - and their far future equivalents. However, even today artillery use can be denied by counter-battery, air strikes can be interdicted by AA or air cover, tanks can be held in check by missiles, minefields, other tanks, rivers without fords and bridges, ... Infantry is for when you don't want to destroy everything. Do you want to use the oil fields and refineries? Artillery and air strikes won't help. Do you want to fill your ships with fresh foods? An already existing population might be willing to provide, or be convinced by means other than orbital strikes on their farm. Do you want to have a safe place for recreation for the crews of your spaceships? A security force is needed if the population is less than friendly. Planets might have value out of proportion to their "worth" if their location in galaxy is crucial, and working with a less than totally hostile local population might be much better than destroying everything and rebuilding (with things brought by spaceship from large distances) [Answer] If your universe has truly trashed everything at the bottom of the gravity well of planets, then there will not be any reason to use planetary armies. Heck, you won't even need orbital bombardment either, because there is nothing worth bombarding down there anyway. But I don't think your description of your universe is consistent with "trashing everything at the bottom of the gravity well". What are the people doing down there? How is the planetary economy related to the space infrastructure? How are they affording all the energy and other imports? Do they truly generate nothing of value to be exported (because, if they do generate things of value and export them to space, then the planets are practically a part of the space infrastructure, which is inconsistent with "trashing everything at the bottom of the gravity well")? If you can make things consistent, then you might get better answers. [Answer] The empire shall return again, as long as there is one man standing, with a working nano-forge-seed. Rebuilding the infrastructure, even with orbital bombardment (deep underground), recloning his brethren, reconquering the skys from guard platforms, building spaceships, retaking the quadrant. One missed soldier. So unless you liquify the crust, you goto search and destroy. Thoroughly. And keep a manned outpost, to investigate returns asap. You dont only have to kick it till its down, you goto make sure it stays down, with continous, expensive violence. Or you sterilize the world, but then why conquer anything at all. ]
[Question] [ > > Here is what we know: > > > * [We have the means to create stable antimatter](http://www.kurzweilai.net/cern-physicists-trap-antimatter-for-1000-seconds) > * [We can direct it in a beam](https://home.cern/about/updates/2014/01/antimatter-experiment-produces-first-beam-antihydrogen) > * [It can travel nearly as fast as light with ease](https://home.cern/topics/antimatter/antimatter-cern) > * [Antimatter and matter combine in dangerous ways](https://en.wikipedia.org/wiki/Antimatter#Preservation): one microgram of antimatter colliding with one microgram of matter can create $1.8\cdot 10^8$ Joules, equivalent to over $40$ kilograms of TNT exploding > > > Theoretically, future weapons could produce antimatter, shoot it as a beam at speeds too fast to react to with missiles, projectiles etc, and annihilate basically anything made of normal matter. In a future where antimatter weapons are common and easy to manufacture, how can spacecraft defend against antimatter beams effectively? Even if this is optomistic and speculative, humor me. Pretend these weapons are relatively cheap (and possible) and that the technology exists. What's a correspondingly feasible basis for the tech to defend against them? [Answer] Don't be there when the antimatter beam arrives. There is no shortage of ways to destroy a spaceship: high-powered lasers, antimatter particle beams, near-lightspeed projectiles, and so on. There's no reliable way to shield a ship against energies of this level. Instead, the basic defense is maneuver. Nothing travels faster than light. The Moon is a light-second away from Earth: this means that if you're trying to shoot something on the Moon with a laser, you don't aim at its current location, you aim where it will be two seconds from now (one second to deal with light reaching Earth, and one second for your shot to reach the Moon). Extending this to space combat, your basic defense is to maneuver randomly, and to stay far enough away from the enemy that you can move the full width of your ship in less than the round-trip time between the two ships. The enemy is reduced to firing randomly and hoping they get lucky. There's historic precedent for this in wet-navy combat: destroyers are fragile, especially in comparison to battleship armament. But destroyers are fast enough, and battleship shells slow enough, that a destroyer at extreme range can move several times its own length in the flight time of a salvo, letting it get out of the target zone. [Answer] The mass-energy in a gram of anti-matter is $0.001 c^2 = 9 × 10^{13}$ joules or about 20 kilotonnes of TNT, that is substantial! (and you get another $9 × 10^{13}$ from the annihilation of the equivalent matter On the other hand, if you accelerate 1g of anything (matter or antimatter) to 0.99 c, it has a kinetic energy of $0.001c^2/\sqrt(1-0.99^2) - 0.001 c^2= 5.5 × 10^{14}$ joules, over 3 times more! Once you have some antimatter, then accelerating it to 0.99c takes exactly the same amount of energy as accelerating the same mass of matter. However antimatter has to be made first, and the process of making antimatter is inefficient: it takes much more energy to make 1g of of antimatter moving at 0.99c than it takes to accelerate 1g of matter to the same speed. The conclusion is that if you can accelerate something to "nearly the speed of light", it doesn't matter whether it is matter or antimatter since the kinetic energy is substantially more than mass-energy. If you get hit by something like this your ship won't survive. The only defence is to not be hit. Tactically this means keeping hidden, and ultimately it means either diplomacy, or shooting first. There would be no benefit in using an antimatter beam, since at those speeds, just using matter would pack almost the same punch. Antimatter could be used as a miniaturized nuke. A gram of antimatter, fired by railgun, would still release 20 kilotonnes on impact, but be a lot smaller than an equivalent thermonuclear weapon. All this is, of course, way beyond current science. Our current best antimatter manufacturing site (CERN) is the size of a city and can make 0.000000001g per year. [Answer] Assume, for starters, that the antimatter weapons produce and fire the simplest kind of antimatter beam. Namely, a beam of positrons. Once your vessel detects an incoming beam of positrons, it aims its own antimatter beam weapons in the direction of the attacking vessel. Both positron beams will be positively charged. This will cause them both deflect and diverge each of the positron beams. Essentially backscattering the attack positron beam and allowing a large volume of positive space charge to build up between the two vessels. Effectively using a positron beam to attack a positron beam blocks it from reaching your vessel. This defence tactic will work best when your positron beam is travelling along the same path of the attacking positron beam. A proton beam beam also be used in the same manner to block positron beam weapon attacks. This will have an added advantage that protons have more mass than positrons, so the proton beam will 'penetrate' further along the positron beam path. The attacked spacecraft can use electrostatic technology to induce a large positive charge on its hull to further deflect the positrons in enemy antimatter beam. If the spacecraft under attack has escort drones or auxiliary vessels in formation with it, these craft can fire electron beams to pass near or adjacent to an attacking positron beam. Since electrons and positrons have opposite charges they will attract each other and cause the beams to diverge from their intended paths. If this is maximally effective the attacking positron beam will miss its target. This effect can be increased if the support craft fire a positron beam that passes on the opposite side of the attacking antimatter beam to that where the electron beam is passing it. The combination of external positive and negative charges will increase the deflection of the enemy's antimatter beam. Another defence against a positron beam would be firing an x-ray laser beam weapon along the beam-path of the antimatter. The x-ray photons in the defensive laser beam will deflect the positrons with Compton scattering. A spacecraft suitably armed with its own positron beam weapons and x-ray laser weapons, supported by escort drones equipped with positron and electron beam weapons, will be able to defend itself against attacks using antimatter beam weapons. [Answer] Since we don't know the density of the beam, we don't know if there's any hope of protecting the ship from a hit. I will assume that we're not talking lightsabers here. That is, a ship could take several shots assuming it maneuvers to prevent the damage from piling up in one area. Cover your ship in an ablative armor made to soak up the anti-matter particles and burn off. As the Ablat annihilates, the surrounding areas not directly struck but caught in the heat, burn and produce smoke/soot particles. These then also absorb anti-matter particles. The Ablat could be manufactured so the burning parts spew soot/smoke outwards, away from the ship. Now the secondary annihilations happen further from the ship. The inverse cube law is your friend. The entire ship does not need to be covered in the thickest Ablat. WWII-era battleships were designed with a 'citadel', a part of the ship deemed critical and up-armored significantly. An ablative armor has advantages: * It is passive armor and works on its own * Burning Ablat carries heat away from the ship * It's cheap compared to the cost of the weapon it is intended to defeat * It's easy to replace EDIT - There were some good questions in the comments. > > How does Ablat handle the radiation generated by mass annihilation? > > > I hadn't thought of that, but it could be made from a material good for soaking up specific types of radiation. Or not - being in space, without warfare, is extremely hazardous due to radiation. Solving that problem might help with this problem. > > How does it burn in space > > > I was using "burning" loosely, but I'd expect the Ablat to include some oxygen in its structure. Basically, we need a chemical reaction that causes particles to be spewn forth. Given there's going to be a flash of heat, some manner of "burning" seems reasonable. > > The hit of antimatter results in a horrific explosion. Thermonuclear > warfare is nowhere near in energy/volume ratio. > > > You don't know how damaging the beam is since the OP has not quantified the strength of the beam. So while what you say is true to my layman's ears, it does not follow that the OP's weapon is necessarily this powerful. > > If an antimatter ray hits a vessel, there's no way any ablation is > going to save its surface. Emitted stream of fast particles just doesn't > work like that. > > > I disagree. If the beam hits, you have a choice - it hits the hull of the ship, or it hits the Ablat. It seems to be Ablat is preferred. There will surely be a hole in the Ablat due to annihilation, maybe down to the hull, who knows. The 2nd beam that hits a little later has to pass through the cloud of "smoke" and this will surely be helpful. I agree that if the beam is dense enough to cause an energy release equal to the power of megaton (or even kiloton) nuclear weapons, there is no chance of the ship surviving unless magic is used. This Ablative armor is not instead of other defenses such as stealth, agility, or spewing clouds of ablative dust. It is in addition to these other defenses. EDIT 2 - Let's talk about "beams" for a second. It is very difficult to make a beam that's not actually a conic. That is, instead of being a cylinder, the "beam" will be wider that the far end. Machinery is not perfect. Also consider the ranges we're talking about fighting. The anti-matter weapon might start out producing a beam, say, 5mm in diameter. 300,000 kilometers later, however, it might be 50m in diameter. The beam is no longer a saw, it's a shotgun. Ablative armor would be very effective against such a weapon. At close range, everyone is going to had a bad day, I think. EDIT 3 - The Hiroshima bomb involved about 700 milligrams of matter being converted to energy. That's about a 15KT equivalent. To get to 1.5 MT, we need 70 grams of matter converted to energy. Safety tip - if that gets loose, the firing ship is erased from the inside. And it may take a long time to generate that much anti-matter increasing the chance of a mishap. Current technology allows us to create hundreds of particles on-the-fly, and it takes the LHC to do it. Between the safety issues and practicality issues, it could be that anti-matter beams are not primary weapons but instead are dandy for point defense. Perhaps they are equivalent to the Vulcan cannons on modern ships, or the 8" guns on WWII battleships. (There is reasoned conjecture that an 8" shell from BISMARCK destroyed HMS HOOD. 8" guns' projectiles had a plunging trajectory. A different weapon for a different purpose...) [Answer] # Your question cannot be answered because it depends on incorrect assumptions. --- First, your claims: > > We have the means to create stable antimatter > > > At already obscene cost, we can create on the order of a few hundred anti-atoms that sometimes last for several minutes. You need more like a billion trillion (10^21) atoms, and indefinite storage. > > We can direct it in a beam > > > This is minor residual kinetic energy from the generating beams, which themselves come from an enormous particle accelerator. To maintain these parent and daughter beams, extremely powerful superconducting magnetic fields are required along with extremely high vacuum--neither of which are reasonable assumptions for the free space between two ships. The beam also spreads anyway. > > It can travel nearly as fast as light with ease > > > No, these are the generating beams, which are pushed to this speed by literally multi-hundred-megawatt powerplants. This, despite containing very little mass. (Initial estimates put power consumption of Cern at 200 megawatts, just to save up enough energy to send tiny packets of protons through the tubes. This isn't easy, and scaling this to a weapon, operating continuously, is ridiculous.) > > Antimatter and matter combine in dangerous ways > > > This is correct, although the energy is typically released as gamma radiation, which is more dangerous to living tissue than e.g. spaceship hulls. (Different reactions are possible. For a proton/anti-proton annihilation, such as you'd get by throwing antihydrogen ions at hull plating, you get a couple loose quarks and some utterly-harmless muon neutrinos.) --- So, the problem here is that to produce an "antimatter beam", inasmuch as that concept even makes sense, you basically need several hundred-megawatt power stations, with all the heat radiators that requires, powering a particle accelerator which is maybe 25,000-30,000 meters in diameter. Then to make it actually dangerous, you need about 100 of these assemblies, and the target needs to be at point-blank range and essentially unarmored. The generating proton beams themselves are much more dangerous, since they have relativistic mass, and you can actually direct them places. *Obviously, if you can afford a power-source that can convert energy into weapons-grade quantities of antimatter in real-time, you might as well instead dump that energy into a whole fleet* of death star lasers. If you really must have antimatter, confine it in bombs. Strategy and tactics for using/defending-against these are identical to nuclear weapons.** [Answer] Today in science we can generate anti-matter, and contain it in electro magentic fields. <http://singularityhub.com/2011/06/11/scientists-trap-antimatter-for-more-than-16-minutes-video/> Quotation from above > > Matter and antimatter make for bad company. When they come in contact > with one another they annihilate as, in a flash, their masses are > converted to energy. The challenge for the CERN scientists then was to > find a way to trap the anti-matter without allowing it to come in > contact with matter. Instead of regular matter, they used magnetic > fields to contain the antihydrogen. But a magnetic field only works if > the particle is charged. At extremely low temperatures–near absolute > zero–antiparticles becomes charged and the magnetic field becomes an > effective barrier. > > > The scientists collaborating on the so-called ALPHA (Antihydrogen > Laser Physics Apparatus) experiment, were able to trap the > antihydrogen atoms for as long as 1,000 seconds–or just over 16 > minutes–“which is forever,” says CERN > > > This is from 2011. Now advance into the future with space ships. The energy and tech to make these fields are probably super easy. Most of space is near absolute 0 anyway except for the radiation left from the big bang. The ability to create 2 fields to form a barrier and drop the temp to near absolute 0 is probably easy. In the future the whole absolute 0 thing is probably made obsolete by advances in tech. > > The reason being that you can not build a container out of pure > electrons, or pure protons, etc… Therefore, magnetic and electric > fields must be used to trap the antimatter. > > > additonal reading material. <http://www.forbes.com/sites/brucedorminey/2016/02/24/antimatter-space-propulsion-possible-within-a-decade-say-physicists/#11f05dfb65f0> [Answer] This weapon would have interesting ramifications. Open spaces become dangerous. You'd hide in dust and gasses. You'd get matter between you and any potential threat pretty quickly. If you could get matter within close proximity to the attacker, the antimatter weapon turns back on itself. Dust, gas, charged particles. Maybe send out a bunch of drones, small and difficult to detect. These drones are able to emit strong magnetic fields (energy is cheap and portable because antimatter) They then feed small and amounts of charged particles into the fields. The charged particles travel at very high speed and can be redirected quickly by shifting the field. Alone these fields are completely harmless, but in the presence of antimatter they become something else entirely. Your enemy charges up his anti-matter beam, your drone flicks on and starts spinning matter around right near his ship. The antimatter beam licks out, immediately interacts with tiny amounts of matter and destroys itself and the ship and anything nearby. Of course if you can get a drone close without being detected you might as well deliver a tiny antimatter bomb with it instead. But as a non-offensive deterrent it might work. [Answer] Erm . . . just chuck normal stuff at it? In [a scene from Star Wars Episode II: Attack of the Clones](https://www.youtube.com/watch?v=05s9TJv77YE), Obi-wan Kenobi is followed by Jango and Boba Fett. They fly through an unrealistically dense asteroid field, shooting lasers that go "pew-pew" in the vacuum of space and essentially defy laws of physics. Jango Fett sends several missiles at Obi-wan's ship. Master Kenobi's first thought? Chuck the spare parts at them: [![enter image description here](https://i.stack.imgur.com/6aPkr.png)](https://i.stack.imgur.com/6aPkr.png) (Two seconds later. . .) [![enter image description here](https://i.stack.imgur.com/pHj4R.png)](https://i.stack.imgur.com/pHj4R.png) The same principle can be used here. Matter and antimatter will annihilate one another. All you need is enough junk that can be destroyed as a shield while you quickly mosey on out of the way. Now, Obi-wan's advantage is that he has a small ship (one Jedi and an astromech droid), a lot of things to block the shrapnel (asteroids), and only a couple of missiles to avoid. In a full-scale battle, with larger ships, this becomes a nearly impossible defense - assuming the beam could be large enough, which would seem to take enough energy such that it could only be fired very few times. Then, you just have to shoot the other guy first. It turns out that [certain types of flares](https://en.wikipedia.org/wiki/Flare_(countermeasure)) are used for the same purpose by aircraft. I wonder if spacecraft could manage to do something similar here, for antimatter beams. The difficulty, of, course, is that flares are designed to confuse the heat-seeking missiles, but you could still likely confuse the beam gunners by adding more lights and explosions. [Answer] Antimatter is not a power source, it's an energy transport mechanism. To generate a beam of antimatter with a given energy content requires generating substantially more power in the ship's powerplant (due to thermodynamic losses), or tapping a Penning trap which can be likened to a battery. How does a ship avoid being destroyed by an antimatter beam? Exactly the same way it avoids being destroyed by a particle beam, railgun, laser, or any other weapon of comparable energy, all relying on converting electrical power to a form that can be delivered to the target. My point is, whatever defenses work for these other weapon types- mostly 'not getting hit' as Mark decribes- will work equally well against antimatter. It's not uniquely destructive weapon so much as yet another method of transporting energy from your ship's power source to the hull of an enemy ship. [Answer] Using current physics, the only way to defend against weapons we can build (antimatter, relativistic beams, nuclear bombs) is to be missed. We are able to concentrate energy at the point where both the electron bonds within molecules, and the electron bonds between electrons and protons, fail. In effect, our weapons are capable of disassembling matter. More advanced weapons will start breaking nuclei. If you aren't at the location the weapon hits, you aren't killed. We are not capable of making weapons that can saturate a solar system (or larger) with deadly amounts of energy; ie, nova-scale or higher. Generally, your only defensive friend is the inverse square law. If they beam their attacks, even better, it becomes easier to dodge. Antimatter is really dross. The KE of relativistic weapons surpasses their mass-energy already; extra effort to send antimatter is pointless. If a relativistic weapons hits, whatever is there is gone, and a large explosion occurs. It is like designing a high-caliber machine gun to fire bullets, but we also lace the bullets with cyanide. In theory, if you could contain antimatter, you could use it as a mine or bomb or energy storage source. If you could efficiently produce antimatter (ie, more less 2 grams of energy per gram converted from matter), you'd have an insane power source; that insane power source would have far larger tactical uses than "throw a beam of antimatter at your target", or even "fire a high-speed missile armed with antimatter". For example, missiles fueled with antimatter could reach higher velocities, because a hard part of getting matter up to high speeds is doing it quickly with a small barrel. We probably don't want to devolve matter down to quark-gluon plasma (or even less structured!) in the barrel of the gun. For any weapon hit to be survivable, you'd need something science-fantasy like force fields. Even shells of defensive matter don't help much, as the collision just turns the defensive matter into more relativistic shrapnel. Your only real bet is to not be where they think you are; random movement. There is no stealth in space, so you have to not be where they think you will be after their light-speed delay. They counter this with smart relativistic missiles, who have large ridiculously powerful thrusters to redirect themselves to match your random movement. As they finish the approach, they turn themselves into shrapnel to cover as large of an area as they can against your final dash. [Answer] vent your waste at it, as soon as the beam hits any normal matter you get an explosion that will disrupt the beam. wipple shields would work too, remember it is still a stream of matter. It would also be worse than useless in an atmosphere, it would actually damage the ship firing it. [Answer] Mobile, ablative armour. Many of the techniques used for stopping RPGs would work, at a larger scale. Oddly little difference between antimatter and a shaped charge, with space(d) armour and reactive armour working here. So, light spaced out armour, capable of moving pre-emptively out to cover holes in protection, far enough to withstand the effects of matter/antimatter annilation. You don't need solid mass and a lightweight, mostly empty material would mean its easier to move it around as needed. So.. Large plates of something like aerogel propelled by small motors with enough freedom as mobile ablative armour, forming a controlled defensive cloud. As units are destroyed they movie to cover holes in the armour, moving inwards. (another model would be [brilliant pebbles](https://en.wikipedia.org/wiki/Strategic_Defense_Initiative#Brilliant_Pebbles) with satillites creating a dumb cloud of lightweight chaff) Alternately they close in on the enemy so firing the gun would result in the ship firing the round annihilating itself. Chaff in this case would be a possibility too. While covering the entire arc of fire in chaff in space combat is impractical at best you could have your interceptors either break into chaff or have local interceptors release chaff after the first hit [Answer] If the beam is charged, then it can be deflected with a sufficiently strong magnetic field, so if the enemies are smart, they will neutralize the beam (this also prevents the beam from repelling itself). So the beam will be antihydrogen. When the beam hits the target (assuming it does), The positrons annihilate, creating gamma rays. The second reaction is between the antiprotons and protons, creating neutral pions (which decay almost instantly into gamma rays), and charged pions. Charged pions have a half-life of 26 nanoseconds, moving at about the speed of light, half of them will have decayed in about 7.8 meters (possibly inside the ship), into neutrinos and charged muons, which then decay into electrons, positrons, and more neutrinos. The positrons then annihilate into gamma rays. The biggest threat seems to be the gamma rays. Heavy metals with high atomic numbers are very good at defending against gamma rays, and they may affect the charged pions (I guess they would be affected by the electrons in the atoms?) If antimatter is cheap, then really none of this matters. If the beam deposits about a kilogram of antimatter on the target, the resulting explosion will be equivalent to about 43 megatons of TNT, and no ship can survive anywhere close to that, even if only 1 gram of antimatter was deposited, the explosion would be 43 kilotons. Practically nothing can survive a hit by an antimatter particle beam. As stated in another answer, the good thing is, you don't have to be hit. If you are 1 light-second away, the enemy will only know where you were 1 second ago. The weapon technology scales with engine technology. If you can have practical antimatter particle beams, you can have practical antimatter engines, capable of multi-gee accelerations at immense efficiencies. So the effect of light-speed lag is increased. If the ship can dodge 1 ship length in 1/10 of a second (VERY high accelerations, crew NOT recommended), the lower limit for combat range is 1/10 of a light second. Any less and it's a bloodbath. And as the capability for dodging increases, so does the capability to saturate the area of possible maneuvers with shots, keeping the probability of hit at a given range stable as technology gets better. Another option for defense would be to operate like a bussard ramjet (great if the ship IS a bussard ramjet). If the beam is neutral, then it cannot be deflected by magnetic fields. But what if you ionize it? Bussard ramjets face the same problem when collecting interstellar hydrogen, and if antihydrogen has the same spectrum as hydrogen (I think it would), a laser designed to ionize hydrogen would be just as efficient at ionizing antihydrogen. Of course, if the beam is moving at near the speed of light, you won't see it until it's right on top of you. So the laser would have to be constantly directed at the enemy, to defend against a sudden antihydrogen beam (or as an offensive weapon), and the deflector magnets would also have to be constantly running. More: <http://www.projectrho.com/public_html/rocket/slowerlight.php#id--Go_Fast--Bussard_Ramjet> <http://www.projectrho.com/public_html/rocket/spacegunexotic.php#id--Antimatter> http: (remove this and spaces) //www.projectrho.com/public\_html/rocket/spacegunconvent.php#id--Particle\_Beams http: (remove this and spaces) //www.projectrho.com/public\_html/rocket/spacewardefense.php#id--Evasive\_Maneuvers [Answer] The method you use for directing the antimatter as a weapon and the method you use for defending against it are going to be closely linked. The simple answer being: # What works for the weapon will work for defence. Somehow you have to manipulate the antimatter into a beam, quickly directed or redirected to use as a weapon, without it colliding with the inside of the weapon itself. Whatever method you use for that will equally work to defend another vessel against the beam itself. At the technological point where antimatter can be used as a weapon, it can equally be defended against. The trick is going to be that nobody would believe you'd use a weapon with such a high risk to your own ship and hence wouldn't have defences against it. This only works once. [Answer] It depends on whether some new technology/physics is invented or not. I present some examples from sci fi. If there is no such thing as super luminar communication, then the detection of an incoming projectile / beam (anti-matter or not) moving at near light speed is going to be useless, as you can't signal to a target to take evasive action fast enough. So, your defenses are either: armour, speed, cover or stealth. 1. Armour: In some books this takes the form of large amounts of ice layered around the outside of a hull 2. Speed: simply moving fast and unpredictably is going to make scoring a hit pretty hard. This will require the ability to sustain high G forces. This naturally leads to the idea of multiple robotic fighter craft/munitions that can sustain very high accelerations 3. Cover: Just stay behind that moon, planet/ asteroid belt 4. Stealth: Maintain a super cooled ship exterior and emit no radiation signature (or angle it away from the likely attacker). If you can't accurately pinpoint your target's location, its not going to be easy to hit it. This leads to a problem of the 2nd law of thermodynamics (that heat has to go somewhere eventually...). You also have to worry about your ship occluding the stuff behind it. If you transit a near by sun, you might get seen. For invented technology/physics: Super luminar detection of incoming projectiles is possible: 1. Just move out of the way (maybe teleport your self!) 2. Teleport the matter somewhere safe, or maybe back at your attacker 3. construct cover using nearby mass by teleporting it into the way 4. detect teh attackers targetting and actively shut down your attacker's systems before shots are even fired 5. Deflect incoming beams using force fields 6. Ablate / absorb incoming matter using force fields traps. For example, a ship with exceptional field management could use matter contained in a field structure to interact with the incoming matter, trap the resultant annihilation photons and construct lasing chambers to create laser beams to shoot at an attacker. 7. Bend space time to curve sufficiently that an attacker's beams end up looping back at the attacker. The list goes on and on... One thing that is certain about all of the above approaches is that they all require some serious computational ability and quick reactions. Hence all will require some sort of AI or battle computer. See Iain Bank's "culture" books for some high tech space battles. [Answer] The thing is, there's a lot we still don't know about anti-matter, because it is so rare and short-lived. We don't even know [how gravity works](https://en.wikipedia.org/wiki/Gravitational_interaction_of_antimatter) with it. So if you are doing this for story purposes, honestly there's a lot you could probably more-or-less make up. For example, its possible that matter and anti-matter repel each other. So if your target is massive enough, or you can create some kind of mass-distortion field in front of it, that might divert the particles. I'm not sure how you'd create a mass-distortion field. But I'm not sure how you're creating enough anti-matter to use in a weapon either, rather than just using the ridiculous amount of energy required to make the antimatter directly against the enemy. Perhaps there's some planet-sized facility, and this is a way to store up that huge amount of energy only available to such facilities into a shipboard weapon. So warships fly around with a set stock of anti-matter ammunition. Since the point of using anti-matter is presumably the matter-destructive properties is has, another defense may simply to be much more massive (regardless of gravitational concerns). To use extreme examples, a planet will shrug off a hit that would obliterate a house. [Answer] If the bad guys can accelerate their antimatter to relativistic speeds, their beam is very likely to consist of charged particles. Positrons or possibly antiprotons, as others have suggested. As cybernard pointed out, physicists routinely control beams of positron or antiprotons with magnetic fields (at places like CERN, FERMIlab, DESY et cetera), making them go around in circles. Which brings me to the suggestion (a variant of cybernard's idea). > > Shield your ownship with a suitable magnetic field. With more advanced tech you could steer the incoming beam into a loop around your ship, and then aim it back at where it came from. > > > A more serious problem might be, if the baddies come from a different part of the universe, where there has been a surplus of antimatter (as opposed to matter as in these parts). Then their entire spaceship would be made of antimatter, including their regular gun shells. Of course, their journey through a part of the universe, where usual matter is the norm, would be perilous :-/ [Answer] The main problem for this weapon is firing the antimatter at the kinds of speeds that the question is proposing. In order to get even small quantities of particles shooting toward your enemy at near-light speeds, your weapon would need to be a pretty serious particle accelerator. The final shot would be at very high speeds, but it would take some time and a lot of energy to get the particles accelerated up to that speed, so the enemy ship would have plenty of warning if they were capable of monitoring power usage, and plenty of chance to disrupt the shot by taking out the accelerator before it is ready to fire. ]
[Question] [ I live in a pre-industrial world, very similar to earth, but with very limited access to magic (no flight, only healing very minor injuries, making flowers grow faster, lighting a candle, etc.). I recently joined a sea sect residing on a vast archipelago, since I wanted to join the worlds strongest navy! However, upon arrival they dyed my hair and irises. No matter how much I try to change it, it (magically) goes back to the same color. On what (cultural / social) basis would they do this? [Answer] # They Own You: Navies are notorious for desertion. The greatest navy in history, the British navy, had to constantly engage in outrageous behaviors (like kidnapping) just to stay staffed with swabs on the deck. Conditions aboard such ships were epically bad. Food was horrible, water worse. They had to hand out alcohol for the crew to mix into the water just to make it safe to drink. And being in the navy meant you didn't get a share in a commercial voyage, but instead had to sail around, intimidating people or looking for fights. So as bad as being a sailor was, being a sailor for the navy was worse. So how do you prevent your sailors from deserting? A sufficiently large navy has a wide range to find people, but it's hard to prove any given person was in your navy. The British didn't care, and would simply stop ships and insist that crewmen on board were British deserters. They did this to a US warship, and it was one of the precipitating events of the war of 1812. This is simply a way to unambiguously mark who is in your navy. If they run off, EVERYONE knows you were in their navy, and are a deserter. It also means that you can readily identify who is on your side regardless of what country of origin they come from. A pirate can wear a uniform of your navy, but as soon as anyone sees the crew, they know the pirates are lying about being from your side. * Another possibility in a world with limited magic is superstition. Green eyes are the "evil" eye, red hair is satanic, and only "normal" hair is acceptable. So they are averting evil by forcing everyone to confirm to social norms. * Another variant is that it is like a buzz cut in the army. Enforced uniformity reduces individuality and reinforces conformity. It is the classic tear you down to rebuild you as a soldier" mentality. [Answer] That magic is keeping you safe! Everyone fusses about the color. The fact is the magic treatment prevents disease! Lice used to be a big deal on ships and louseborn disease was a significant cause of illness. Also, sailors in tropical areas suffered greatly from fungal and bacterial skin diseases. Worst of all were diseases transmitted by flying insects which sometimes take up residence in the bilge. No more. Now the magic protects sailors from all of that. You can keep your pretty hair and you don't have to worry about lice. No scratching yourself raw because of fungus. No terrible fly-borne scourges. Sulky sailors moan "they dyed my hair with magic. Woe woe woe!". OK, effectively we did. But that color (and skin color if you look close; also eye color) is a byproduct of what we really did - keep you safe! [Answer] It is a sign - and proof - of membership. Only the sea sect knows how to create those exact colors, so everyone with this hair and eye color is trusted by everyone to belong to the sea sect. This means the sea sect's fame as traders/explorers/fishermen/mercenaries/... is extended to all bearing the colors. Even if you and your crew have never been in a given port, most people will treat you better then total strangers. Also, sea sect members can easily recognize each other even if they have never met in person. Great for helping each other out. And for hunting down those members that try to run away before their duty is done. [Answer] They don't want their secrets out with the wind, and since you are in, they want to be sure you will never be out, telling some outsider what they want to protect as an important secret, be it how to make Greek fire or the recipe of their water-less stew. You should have listened more carefully to the last verse of the anthem all trainees are forced to learn > > Last thing I remember > > > I was running for the door > > > I had to find the passage back to the place I was before > > > "Relax," said the night man > > > "We are programmed to receive > > > You can check-out any time you like > > > But you can never leave!" > > > [Answer] ## It shows your rank and function within the organisation. All novices have the same hair color. When you get promoted to higher ranks within the organisation, you undergo a ritual where your hair- and iris color will be changed to a different color matching your new rank. This ensures that everyone's rank is immediately visible. It makes it very difficult to impersonate people of a higher rank. When the rank insignia were just a piece of clothing, then any novice could steal a priest robe from the laundry and suddenly they would no longer stand out while snooping around the secret library of forbidden knowledge. But as you said, there are wards against changing your hair color to something else. So anyone with novice-colored hair in an area that's off-limit to novices would stand out immediately. [Answer] It's mermaid repellant. Mermaids (and all mer-kind) are a widely varied bunch, especially in their relationships with humans. Some avoid humans. Some eat humans. Some are friendly to humans. Some marry humans. The sect's navy got tired of sailors being killed accidently while being pulled deeper and deeper into the sea for each kiss from playful mermaids. No matter what precautions were taken, sooner or later more sailors ended up drowning. Some in the navy proposed war, but merkind are fearsome opponents and the navy had enough other enemies to deal with. Then the solution was found. Yet another member of the sect slipped off an anchored ship to cavort with a mermaid. He was a few kisses away from being dragged too deep when the mermaid let go and quickly swam away. As he swam back towards his ship, she surfaced near him. Still being too distracted to realize how closely he had avoided death, he asked why she'd let go. "Didn't you see it?" ‚ÄùSee what? A shark? A whale?‚Äù A small, very bright green fish swam by. She screamed and covered her eyes. "It's horrible! Make it go away!" "It's just a liitle fish. Is it poisonous?‚Äù he asked. "No, it's the color. There's something wrong about that color. I can't bear to look at it. None of us can. I'll be ever so grateful if you chase it away.‚Äù Word of this encounter reached the ship's captain. After a few weeks of searching, a fish like the sailor had seen was captured. Just a quick glance at it sent mer people fleeing. More fish were captured, but keeping fish between the sect's sailors and dangerously playful mermaids wasn't easy. One day, after a few too many rounds of rum, someone suggested making a hair dye of the exact same shade. It worked, but only lasted for a few days before fading. Something more permanent was needed. Eyes were included to protect bald members of the sect. [Answer] The color change is only the outwardly visible signal. Some internal change has happened, and the color lets certain people know it has properly taken. Depending on exactly what the nature of the sect is, it could be nice, boring, or nasty. Maybe even nightmarish. * Now you taste good to somebody. Or something. When they get hungry you better be careful. This could be that you are literal food, or a host, or subject to mind-control. * Now you taste bad to somebody. The color tells them not to take a bite. * Now you can see the Fnords! (Yeah, that book is too long to explain, but it's in the Illuminati books.) * Now you won't catch certain diseases. So you can act as assistant to the healers when the repeating epidemics happen. Can't give it to everybody because there are only about 50 doses made per year. * The Powers That Be are very vain about their hair. Your hair is now the exact right color to make wigs for them. The eyes are a side effect. * Now you are a match for forced organ harvesting. Not just eyes and hair, but lots of other parts. You will wake up in several different recipients. [Answer] ## Preventing Racial Tension Maybe this is a world where instead of skin colour, eye and hair colour are what people use to divide themselves up. Have the wrong hair or iris colour in the wrong part of the world and you're a target for intense discrimination and abuse. The navy has had so much trouble with crews of different races descending into conflict and violence between themselves, that they've taken the drastic step of essentially making everyone the same race. Of course, that isn't going to magically fix things, as much as in our world you can't just make a European person look Chinese and that will fool a Chinese person for longer than a few sentences of conversation (or any at all if they don't speak the language!), but perhaps in the regimented and culturally homogenous navy, where individual cultures are cast aside in favour of a unified military culture, it's enough to stop the violence. It could be seen as analogous to a school dress code or uniform designed to prevent gang violence by students wearing identifying clothing. You could also flip the narrative, and instead have a navy that believes very much in "assimilating" other races, to the point where they physically change their recruits appearance so everyone looks like their race. [Answer] ### Superstition or otherwise religious beliefs Naval combat is not fancy until the modern era. Firing cannon on the high seas won't be effective from long range. The cannon itself is not really accurate. The ship is wobbling. So does your target, wobbling and riding the waves. Usually the ships will try to get closer first before opening fire and raiding/boarding one another. Surprisingly, your naval sect can* fire accurately from long range, making battles with other navies rather easier.* It does not guarantee 100% win rate, but often enough to damage the other ship very significantly even before it can get close and return accurate fire. Some will say that your cannon operators and spotters are secretly very talented. Some will say it's just very high and pure luck. Some will say there's just a confounding variable that no one knows yet. But your navy, oooh, they believe the gods helped them. Because gods like to see their subjects win fights. That's why they mandated a magic-locked color change done to some part of your body. To appeal to the gods and praising their likeness. ]
[Question] [ One day on planet Earth, for reasons that are not immediately apparent to the population, all natural sources of oxygen production stop producing oxygen. No new oxygen is output from any natural source, whether it be on land, from the oceans or elsewhere. How long would it take for: 1. Humans to notice that no new oxygen is being output? 2. Earth to no longer become livable for humans/other typical Earth life? [Answer] All the info we need to calculate this is in the wiki for the [oxygen cycle](https://en.wikipedia.org/wiki/Oxygen_cycle). The atmosphere gains and loses about the same amount of oxygen each year: 3 $\times$ 1014 kg. It also currently holds 1.087 $\times$ 1018 kg (34 $\times$ 1018 mol converted to kg). So we could, back of napkin, last 3,000 years. In reality we would either die much earlier because not even sherpas could breath in an atmosphere with 60% reduced oxygen concentration (at sea level, effects would be deadlier at higher altitudes), or survive much longer because 3,000 years is way enough time to come up with some technology to allow us to survive at least in bunkers. By the way, scientists would notice this really quickly. Plants in labs would act weird around the world (there are many labs experimenting with photosynthesis, you know). You would also have massive acidification of lakes and oceans right away, since all that phytoplankton stopping producing oxygen would be almost equivalent to all of it dying suddenly. They are the major source of O2 for surface water, since atmospheric oxygen takes longer to diffuse into water than plankton takes to replenish it. So... this might make major news within a day or two. Most probable scenario: scientists warn about the end of the civilized world within the century, deniers claim it's a conspiracy theory to plant microchips in everybody through vaccines (the less sense it makes, the more they love it). Politicians argue in circles about what to do for decades without any practical actions taken. 100 years later historians are discussing about a time when people lived outside bunkers. But the average, future bunker citizens think that's a plot to socialize oxygen, which they won't allow. [Answer] The limiting factor on survival would be food. No photosynthesis = no plant growth = no new food. The world very soon turns into the Rwandan genocide + cannibalism. Even with full recovery of the bodies you're looking at about 3 years before the world is reduced to bacteria. [Answer] It's not the lack of oxygen so much as the accumulation of CO2 that we would notice first. And that would happen far sooner than we would notice the lack of oxygen, per se. (I'm addressing when the average human would experience a difference in daily life, not whether scientists would notice the atmosphere changing, something that would take very little time.) Today, atmospheric CO2 is around 0.04% worldwide. If plants stop synthesizing CO2 into glucose (photosynthesis) and the atmospheric CO2 level rises to just 0.5%, we would notice its effect on our daily routine almost immediately. For example, at 0.5% ambient CO2, astronauts on the ISS "experienced headaches, lethargy, mental slowness, emotional irritation, and sleep disruption" ([source](https://en.wikipedia.org/wiki/Carbon_dioxide#Toxicity)). At 1% CO2, we would notice our bodies reflexively trying to breathe better. We can survive CO2 levels between 1% and 2% for only about one month. We would survive for 1 week at 3.5%, and 8 hours at 4.5%. Medically, the resulting condition of too much carbon dioxide in the blood is called [hypercapnia](https://en.wikipedia.org/wiki/Hypercapnia#Tolerance). I understand that this occurs because CO2 does not leave our bloodstream efficiently when the partial pressure of CO2 in our lungs is too high. (Chemists, feel free to correct me.) --- How long would this take? A rough calculation: Mass of atmospheric O2: 1.4 × 1018 kg O2 ([Table 1](https://en.wikipedia.org/wiki/Oxygen_cycle#Capacities_and_fluxes)) Mass of atmospheric CO2: 1.4 × 1018 x (0.04/20.9) x (44/32) = 3.7 x 1015 kg CO2 [The line above converts current O2 mass to current CO2 mass via two ratios: their relative % of the atmosphere, and their relative molar masses.] Annual oxygen production: 3 x 1014 kg O2 ([Table 2](https://en.wikipedia.org/wiki/Oxygen_cycle#Capacities_and_fluxes)) One year of respirated CO2 not converted back to O2 via photosynthesis: 3 x 1014 kg O2 x (44/32) = 4.1 x 1014 kg CO2. (This is the annual increase in CO2 if there is no natural production of oxygen.) CO2 is now 0.04% of the atmosphere. It needs to grow by a factor of 12.5x to reach 0.5%, by which point we would certainly feel the effects (see ISS astronauts above). This requires adding 11.5 x 3.7 x 1015 = 4.25 x 1016 kg CO2 in total. At an increase of 4.1 x 1014 kg/yr CO2, this would take 104 years. Short answer: We would all suffer "headaches, lethargy, mental slowness, emotional irritation, and sleep disruption" no later than 104 years from now. In reality, people [already experience these things](https://www.vox.com/2014/8/6/5971187/carbon-dioxide-indoors-air-pollution) after a couple of hours in closed bedrooms, offices, and meeting rooms with poor ventilation, as ambient CO2 increases, so such problems would become commonplace far sooner than a century. --- So without technological intervention (say, reducing CO2 levels indoors), we would suffer serious effects even with abundant oxygen all around us. It would be analogous to floating in a lifeboat in the middle of the Pacific: "Water, water everywhere, and not a drop to drink." [Answer] I'd like to offer a different approach to your question, which was already briefly mentioned (as in [this answer](https://worldbuilding.stackexchange.com/a/187185/66680) and [this comment](https://worldbuilding.stackexchange.com/questions/187147/if-all-natural-sources-of-oxygen-production-stop-how-long-do-we-have/187192#comment580817_187147)): oxygen, more accurately molecular oxygen (O2) is not a "purposeful" product made by plants, algae or bacteria. Quite the opposite, molecular oxygen is a by-product of the reduction of CO2, and by the way a very toxic by-product, which the autotrophic organism needs to get rid of as soon as possible. In short, this is the reaction: ![](https://latex.codecogs.com/gif.latex?2H_%7B2%7DO&space;%5Cleftrightharpoons&space;4H%5E%7B+%7D&space;+&space;4e%5E%7B-%7D&space;+&space;O_%7B2%7D "2H_{2}O \leftrightharpoons 4H^{+} + 4e^{-} + O_{2}") The protons and electrons are used to reduce the CO2, allowing the production of organic compounds, and the O2 is quickly discarded (or itself reduced, e.g. respiration). All that being said, the real question becomes: > > If all natural production of organic compounds1 stop, how long do we have? > > > That, I'm afraid, will have consequences much deeper and faster than the depletion of atmospheric oxygen (which may take longer before it starts affecting aerobic organisms) or the increase in atmospheric CO2. Lack of organic compounds, aka food, is the main issue here. Just think about the sun disappearing: no more light, no more reduction of CO2, no more food. It's roughly the same scenario. --- 1 There are other biochemical pathways for reducing the CO2 without oxidising water, but they are negligible. [Answer] > > 1. Humans to notice that no new oxygen is being output? > > > Immediately they notice all the plantlife is dead. The only way all plants would stop producing oxygen is if they're dead, it's not a choice they make, it's a necessary biological function. > > 2. Earth to no longer become livable for humans/other typical Earth life? > > > Shortly after 1) when the nuclear holocaust starts after they find out all the plant life is dead. [Answer] Photosynthesis is the bedrock upon which almost all life on this planet ultimately depends. No photosynthesis means no phytoplankton or plants, and no phytoplankton or plants cuts the bottom out from under the food web. Herbivores and their aquatic equivalents quickly starve as their food all dies, and then the predators of those herbivores starve, etc., until what's left are mostly carrion eaters and other decomposers like fungi, bacteria, etc. And eventually even those will eat their way through all of the other once-living matter and die themselves, leaving the world covered in nutrient-rich but lifeless dirt. The only survivors would be a few pockets of life based on [chemoautotrophs](https://en.wikipedia.org/wiki/Chemotroph) at places like deep-sea vents, which get their energy from breaking down chemicals like hydrogen sulfide or ammonia. Theoretically they could eventually expand out into the rest of the world, but given the extreme conditions that most chemoautotrophs require, it's unlikely that they'd be able to spread far from their specialized energy sources. Humans might muddle along for a while relying on stored food, but unless there's a major breakthrough in turning waste and raw nutrients back into food on a massive scale in a way that doesn't involve plants at any step, we are eventually going to run out of food and die. [Answer] When deoxyhemoglobin picks up oxygen, that's a chemical reaction (forming oxyhemoglobin). When oxyhemoglobin releases oxygen, that's a chemical reaction too (forming deoxyhemoglobin plus oxygen), and that seems to me that it's no less a "production" of oxygen than photosynthesis. So it seems to me that the answer is that we would all die very, very quickly. ]
[Question] [ In the story I am writing right now, a scene portrays the attempt to kill the main character in his own apartment. After having studied the floor plan, the assassin decides to shoot him from the neighboring flat - through a wall. Here is the full plan: * The watered closet of the target's apartment is adjacent to a small, windowless room in the neighboring apartment that allows for safe, stealth operation. The wall separating the toilet from said room is fairly thin. * After gaining access to the neighboring apartment and quietly neutralizing its occupant by means of chloroform, the assassin enters the room. He carries his equipment in a sports bag. * The assassin listens for the flush of the toilet so that he can locate the seat. * After that, he uses chalk to mark a spot on the wall roughly corresponding to where the upper torso of the target would be when sitting. * The assassin waits for the next toilet session of the victim (he has previously put a diarrhea-causing substance in his food). As soon as he hears footsteps and the clanking of the toilet lid and confirms that the target is seated, he aims at the marked spot and shoots through the wall. * He then uses the hole created in the process to check up on the victim and/or administer more shots in the case of survival. My questions are: * Is this setup realistic? * What weapon, preferably with silencer, can be used? [Answer] It might work as written, *but* has a simple issue: *you specify this is an apartment building.* This means that odds are high that the toilet room wall is what's called a "wet-wall" in construction and building design: they stack the toilet rooms, floor over floor, and organize the piping so that it runs vertically through the thickened wall or through a chase, typically directly behind the toilet. It's therefore probable that there are not only pipes, but likely multiple quite *large* pipes running through that wall: water supply pipes (large), waste outlet pipes (larger), and stack vents (smaller) - the stack vents run all the way to the roof (or sometimes have wall outlets depending upon locality) and all others run from top floor down to lowest level where they connect to the mains. These pipes are typically passing through floor-ceiling assemblies with fire caulking and other fire and smoke suppression sealants and systems, meaning there's little sound transmission between floors or along pipes, other than water hammer sounds inside the pipes themselves. To convincingly work with this reality, I suggest: After the assassin chalk-marks the spot on the wall, they use a hand-auger (old fashioned un-powered slow *quiet* drill) to bore a hole through the wall covering in the room in which they're waiting, allowing them to visually inspect the piping behind the wall surface to determine the best shot location, *and* place the muzzle directly into said bored hole, so that when they do fire, the main sound is inside the wall cavity and thus resonates less, being restricted from open air expansion and reverberation, and what sound is propagated will sound enough like water hammer as the pipes will partially resonate to the gunshot to be easily ignored. [Answer] If he can get a laxative to the target, why not a poison? If he can get to the neighbor silently, why not the target? Now if the task is to setup the neighbor using the neighbors own gun in some sort of 'accident', then this would make sense. There needs to be a reason for the complexity behind it. [Answer] People have already done a good job of answering the realism aspect here, so I'll just focus on weapon choice. Overall, you have a couple of constraints for this type of scenario: 1. The weapon has to be compact. Conventional sniper rifles like you would get from PGM, Accuracy International, or other big firearm companies are pretty much out, they're way too long. Even a more conventional rifle is likely to be a bit on the large side here, as they are typically at least two feet long. This largely limits you to three options, a handgun, a bullpup rifle or PDW (one where the chamber is behind the grip, examples include the Steyr AUG and the FN P90), or a military CQB carbine (like the US M4 carbine). Note that this is factoring in the use of a 'silencer', which are usually at least 10 cm long. 2. If you want it to be quiet, you need a subsonic round. Contrary to popular belief, a 'silencer' does not actually make a gun silent, which is why they are typically instead called suppressors. There are three sources of sound when firing a gun, the detonation of the powder load in the cartridge, the sonic boom from the bullet itself, and the mechanical sounds of the gun operating. A suppressor only takes care of the first source (the sound of the detonation). To deal with the second source, you need a round with a velocity of less than about 300-320 m/s. That immediately eliminates almost all handgun cartridges except .22 LR, .25 ACP, .32 ACP and .45 ACP, and a vast majority of widely available rifle cartridges. 3. You want something that's not going to over-penetrate your target. Overpenetration, somewhat paradoxically, actually increases the chance of survival in most cases (terminal ballistics gets really weird sometimes). It would also risk hurting someone other than your target. This would normally mean hollow point or soft point rounds, but both are out as options if you're shooting through a wall (the wall will cause them to expand, instead of them expanding in the target as needed. This leaves you with needing something reasonably low power to begin with, or that just naturally tumbles or expands in your target. Given all of this, you've got a pretty limited set of options if you want something that actually exists today. Modern bullpup designs generally are not very flexible in terms of chambering (and thus will be hard to meet the second and third requirements with), and most handgun rounds that meet the second requirement require being essentially right next to your target and aiming directly at a vital organ like the heart to reliably kill someone (.22 LR will bounce around in the chest cavity though, so that might be a decent option here). An FN P90 might work for this (and would look really cool too), the 5.7x28mm rounds can easily punch through a wall (the military loads can punch through NATO issue body armor at 100 meters without issue), will tumble inside the target (this is a side effect of the shape of the bullet), and are not particularly loud (they are supersonic, but it might be possible to do a custom subsonic load that works with a suppressor, and even if not it won't likely be loud enough to cause trouble), and the gun itself is really compact. Realistically though, the most likely option if the assassin is well funded is going to be a custom made weapon chambered in something like .300 BLK (a rifle round designed for optimal subsonic performance and good ballistics with a suppressor), either in a bullpup arrangement, or built similarly to a pistol-configuration AR-15 (that is, one with no stock and a short barrel). [Answer] Its incredibly far fetched and completely unnecessary but yes it's possible. A .50 caliber round will go straight through a brick wall and kill whatever is on the other side, but its trajectory will be altered somewhat but seeing as the victim will only be a foot or so away from the wall its a guaranteed kill, 5.56 weapons can be silenced as can 7.62 weapons, both can go through brick walls but with more trajectory change. But realistically if they were able to get inside next door, and that close in general, a hit-man would probably just pick the lock and kill him in the middle of the night and to be fair a knife is as silent as is possible. the assassin is more likely to leave evidence that can be linked back to him if he stays next door for such a length of time, whereas picking the lock in stab out is unlikely to leave much for the authorities to go on, or when the victim is home just walk in next door plant a few kilos of plastic explosive and walk out, when a safe distance away flip the trigger cover (any good detonator MUST have a red trigger cover!!!) and press away, removes most if not all evidence the assassin may have left behind in that brief time [Answer] I'd like to suggest a variant with a bit more enhanced realism, in that he doesn't have to take any chances or make guesses (pro assassins would hate an uncertainty!), and also keeps very closely to the original idea, but addresses a few points mentioned in other answers/comments, if it doesn't spoil the intended plot. Also as much drama, and perhaps able to keep a reader guessing even more Most toilets/bathrooms have a sink to wash ones hands. The sink has some interesting features for an assassin behind a wall - it's more often towards a far end if there's space, and it almost inevitably has a mirror (either over the sink, or if not, then a full size wall mirror as in some disability-friendly toilet/bathrooms). The mirror is what we want. It's separate from but flat against the wall (or flat against the sink's back panel/wooden units), and it's quite large. Imagine the current plan. Marking an X on a wall and hoping the target isnt leaning forward, reaching sideways, holding their head bowed, reaching for thre paper or their trousers .... and if he misses and the target drops down low, how to figure his aim for a second finishing shot? No, the guesswork is far too much for a skilled assassin. But he wants to shoot through the wall anyway. Can you see where I'm going? Instead of a hole by the toilet or a blind shot through the wall, the assassin first locates the mirror in the bathroom. This should be fairly straightforward for the kind of assassin in the question. He could: * use a cheap metal/pipe detector as sold by any DIY chain, to locate and trace the sink pipework * use a long range view with binoculars, somewhere he couldn't shoot from but could view from * somehow gets a description from a past visitor/tradesman/associate * figures from the floor plans that most apartments have the same layout which pretty much forces the toilet in one corner and sink on the opposite wall * drills a tiny pilot hole somewhere else, like at floor level under the toilet/sink, and passes a fiberoptic size tiny fisheye lens through it to view the layout. (My favourite of these!) He/she then carefully cuts/drills away a fair size hole behind the mirror of the sink, stopping when close to breaking through the wall to go really slowly. This isn't hard because walls in any specific building are almost always similar thicknesses. Noise isn't a problem - from time to time anyone's neighbour will do building work and everyone will assume that's all it is. So he doesn't need to know when the target is out or in a meeting. He might use an ordinary cheap angle grinder with a diamond blade, as used by any DIY/builder, instead of a hammer/chisel, because this cuts the wall away without putting any pressure/force on it. It would take maybe an hour or two to do it. So when nobody's around to hear, he can expose a sizeable area of the back of the mirror through the wall, like a rough circle 4 - 6 inches across, and it can't be detected. And now, remember one key thing about mirrors. You know the one way mirror beloved of police interview rooms in thrillers? All that a one way mirror is, is a half silvered mirror with the "hidden" side in the dark. The person on the lit other side only sees their own reflection. So your assassin turns off the lights in the next apartment, and with a fine abrasive, gently rubs the back of the mirror through the wall, stopping once he can slightly see through any part of it. If his rubbing is careful and fine (and he's practiced it of course!) then he's now converted his target's toilet/bathroom sink mirror into a makeshift one way mirror. There's no sign of it (who looks hard at their sink mirror?), and it's dark his side anyway. But when the target comes in and sits down, he has a perfect sight for his hit, down the barrel of his gun, of the target with trousers round ankles on the toilet (or standing stationary looking at it), and all that lies between them is a thin sheet of glass. Even if the target moves, the hole is large enough to see everything and adjust his aim sharply downward. And being the other end of the bathroom, its a great vantage point. He might figure as a fallback plan, even if the toilet location was wrong (they moved it in that bathroom), this will give him a good shot anyway, when the guy washes his hands, even though toilet is preferable because of immobility and trousers obstructing movement. Shot through the wall, and guesswork removed. Bye-bye target! [Answer] I can't speak to your method of target acquisition, but as evidenced by [this video](https://www.youtube.com/watch?v=AXOIQgfvVlE), almost any firearm will massively over-penetrate drywall or Sheetrock. I know it's a short answer, but I don't have that much more to say. Nearly any gun will go through the wall, and I don't see why you couldn't figure out where to aim with a detailed floor plan. All that said, if you're okay with B&E and Chloroform, why not just skip the elaborate plan and chloroform the target directly? [Answer] It is possible, but there are some nuances you might add if you are into exposition and tangents (like Neal Stevenson, for example). The wall is likely to be an extra-thick wall. Not with more layers of covering, but with greater distance between the two layers. This gives a greater internal cavity space for plumbing to be run. When constructing the thicker wall with standard studs, the construction is often done as two half walls, each with its own header, footer, and studs. The studs on one side often do not align with the studs on the other, so even though a stud finder could keep the assassin from firing directly into the stud on the assassin's side, the weapon could still be deflected or absorbed by the stud on the victim's side. With so many pipes inside the wall (drain, vent, hot supply, cold supply, perhaps greywater supply) the assassin would want to avoid hitting them, as they could deflect a weapon. How are the walls finished? Ceramic or stone tile would be a greater impediment to a bullet than would gypsum wallboard. The assassin could manually penetrate the wall on the assassin's side, which would give the assassin information about the internal structure. Because the bathrooms are back-to-back, they probably share a drain pipe. With the right robotics, the assassin could approach from the neighbor's toilet, navigate through the trap to the common drain pipe, cross to the victim's toilet, through that trap, and proceed with the mission. Projectiles, explosives, injections, gasses, poisonous spiders, and other attacks become possible. [Answer] Simple answer is yes, and he could do it from farther away too: <http://www.dailymail.co.uk/news/article-3382593/SAS-sniper-kills-3-ISIS-bombers-10in-wall-kilometre-away-world-s-powerful-rifle.html> [Answer] If the assasin has gained entry into the apartment, it would be easier to rig the toilet to explode, rather than mess around drilling holes. (This idea is stolen from Chris Ryan's book, Hunter Killer). An explosive device contained within the cistern, along with a small web-cam, will ensure positive identification of the target, and a very high chance of success. The cistern would act like a Claymore, ripping the toilet's occupant to shreds, and providing the device is large enough most evidence will be destroyed. (Shooting the guy might tie the assassin there due to ballistics and other forensics found, and has to be there onsite for the kill, but a remote explosive allows our assasin to be on the other side of the world, with minimal evidence tying him to the scene) [Answer] As many people noted, it is far too elaborate and has too many unknowns (like hitting unexpected pipes or offset studs). Some simpler methods might include: 1. A sniper rifle, binoculars and a thermal imager. The assassin across the street (no need to make entry into the building) watches through a window to see the movements of the target. When the target is PID ((Positively Identified) and going into the washroom, the assassin takes up the sniper rifle with thermal imager and lays onto the area where the toilet is (this can be determined by the floor plans). Under the right conditions, the ghostly image of the target comes into view and the assign snipes the target as the target settles on the toilet. [![enter image description here](https://i.stack.imgur.com/0rgcL.jpg)](https://i.stack.imgur.com/0rgcL.jpg) Image using a FLIR (Forward Looking Infra Red) device. A thermal imager would provide a similar image 2. The assassin rigs a weapon to a quadcopter drone and flies it in through the bathroom window. This can be as simple as a hand grenade sized bomb, or even an actual pistol or PDW type weapon. [![enter image description here](https://i.stack.imgur.com/ZRHgN.jpg)](https://i.stack.imgur.com/ZRHgN.jpg) Surprise! 3. If you really want to have an elaborate assassination scene, follow the "Wrath of God" team which tracked down and killed Black September members after the Olympic Massacre in Munich in 1972. According to the book "[Vengeance](https://www.amazon.ca/Vengeance-True-Story-Israeli-Counter-Terrorist/dp/0743291646)", by George Jonas, the team found Mahmoud Hamshari in Paris, snuck into his apartment and placed [a small explosive device in the handset of his telephone](https://www.britannica.com/topic/Operation-Wrath-of-God) (this was 1972, so things like cell phones had not yet been invented). When he came home, the Mossad agent simply dialled the number, asked if this was Mahmoud Hamshari and when he received confirmation, triggered the device remotely. Since the explosion was being held to the side of Hamshari's head, Mahmoud Hamshari died of his injuries. 4. For an up to date version of the phone bomb, the assassin looks for a shot through a window. Ideally the victim will be sitting with their back to the window, and the assassin can call on his cell phone or contact him via social media if the computer is against the wall and the victim sits with their back to the window. The assassin can activate the phone of computer camera by remote control or [hack](https://null-byte.wonderhowto.com/how-to/hack-like-pro-secretly-hack-into-switch-on-watch-anyones-webcam-remotely-0142514/) to confirm the victim is actually there, and even (gruesomely) record the effects of his own work once the shot is made. (Note. understanding how this is done is not the same as condoning hacking people's computers. Use this information to secure your own machine). Update to add: Why shoot if you can get enough explosive hidden in the phone case or computer/laptop case? The assassin simply uses the camera or microphone to PID the target, then detonates the device with the target in close proximity. Of course depending on the skill of the assassin, the notoriety of the victim and the needs of the body sanctioning the hit, the assassin could simply fill the basement of the building with a large explosive device and level the entire structure, with the trigger being the flushing of the victim's toilet..... [Answer] I feel this is needlessly complicated, if your scope is "figure out where they are through a wall and shoot them" then using either a FLIR unit or some form of penetrative radar imager to identify them will probably be sufficient. The radar imager has the advantage of being able to also see any obstacles inside the wall such as pipes and structural beams that might stop or deflect the shot. Neither option requires physically gaining entry to the apartment or takes longer than a few minutes of setup and packup. The getaway being a vital component of the plan because when the neighbours hear a loud gunshot from inside their building then the police won't be far away. [Answer] Others have covered the process of locating the person, I would think a fine drill and a fiber-optic cam close to the floor/ceiling would be good enough to inspect the room and locate the occupant. I would consider a shotgun as the weapon of choice, possibly a suppressed 12 gauge like [this](https://www.youtube.com/watch?v=rtIqTfObXIo%20%22this). It's nothing like silent but you could theoretically use a 20 gauge in a similar configuration without being in sci-fi territory. Either way with buckshot at < 3 feet you've got a little more forgiveness regarding accuracy because a bunch of shot will carry more stopping power and has more chances to ruin something important. Alternatively as someone suggested a suppressed SMG, you could fire a burst from head level down and likely get something important, subsonic loads or hollow points would do fine since a burst will clear the drywall anyway. Finally, consider basically a spike, like an estoc, smallsword or even a pointed bit of rebar with some duct tape on the back. If you grant that the person can locate the target effectively, you may as well just remove all wall material except the drywall on the target's side, make a small divot to rest the point. Then wait for their arrival and brace the blade against the wall, when they're in position you just lean into a heavy thrust, you'll easily clear the wall and strike the target in the head, neck, torso. Depending on the arrangement you've definitely stricken them and possibly/probably killed them, possibly you've pinned them in place. Either way it's far quieter as regards the weapon and may indeed be quieter from the target if you get it where you need to. [Answer] After gaining access to the neighboring apartment and quietly neutralizing its occupant by means of chloroform, the assassin enters the room. Other answers have pointed out a lot of problems with neutralizing the neighbour, most/all of which suggest entering the target's apartment is the superior choice. If you really want this plot device, I'd suggest making the neighbouring apartment vacant instead. Occupants at work, away on vacation, unit currently for lease, renovations, bug bombs, loads of ways to do that. [Answer] If you've gone to all that trouble, why not just cut a small hole in the wall? That way, you can establish if there are any pipes in the way, see that your target is where you expect them to be (guys pee standing up, which might throw off your sighting) and then use a silenced .22 without losing any velocity from going through the wall. Consider some more creative approaches to taking someone out while they're on the commode... You could feed your target 3000 cheeseburgers so they die like Elvis did... on the toilet. Put a cobra in the toilet so they get nailed when they sit down (and leave a memorable mental image for your readers to remember the next time they have to go) [Answer] As others have said a sniper rifle can punch through walls. But killing a target with poison is just as easy as making them need a visit. In as far as aiming without the toilet setup, a blind assassin could use a microphone to locate the target from echos and familiar sounds. > > He Hears a tap, he is at the sink, 18 steps and hears a china cup, he is at the bedroom coffee table. > > > The assassin would either need a knowledge of the apartment from a seeing accomplice or use known fixtures such as taps and light switches which would be available from a city planning office. [Answer] I think you are better off shooting from the upstairs neighbor's apartment. Shoot the victim while he's in bed. This does a few things for you. 1. You have ~8 hours to set up and aim, whereas your bathroom plan only leaves you a few minutes. Maybe seconds if you do wait for the flush. 2. You know exactly where the victim will be. In the bathroom idea, you don't really know if the victim is standing or sitting when he flushes. This is enough of a difference to make you miss. 3. You can be sure it is the victim you're shooting, not a guest that asked to use the bathroom. [Answer] As I believe others have said, inducing food poisoning seems unnecessary. The victim will go to the toilet sooner or later in any case. The assassin would have the problem of gaining access to the neighboring apartment. A simpler solution is to ring the doorbell. While the suspicious future victim might use a peephole, the assassin can simply fire through the door. To keep the firing through walls scenario, you may wish to specify that the neighborhood is unsafe enough that all the front doors are heavy reinforced doors without peepholes, and that the victim has a video interphone system. If being in the neighboring apartment is interesting from a plot point of view, I have a more geeky method to suggest. It is possible to use radio waves to detect humans through walls, see [recent MIT research](http://people.csail.mit.edu/fadel/wivi/). The equipment could probably be disguised as a normal computer or two. Rent the neighboring apartment, calibrate the system, wait until the victim is stationary (sleeping, for example), and then fire. Then run to ring the victim's doorbell, crying that you're very sorry but you were cleaning your gun and it went off and you hope nobody was home . . . frightened . . . hurt . . . dead? Oh no! [Answer] The apartment building is cheaply built with Pladur/Durlock. This material is very fragile and thin. you just have to locate the wall without plumbing. Bathroom walls are made of Pladur -N, a water repellant version that is only 1.2cm thick, but has a surface absortion ratio of 180gr/h \* m2. You could probably just fist-smash trough the wall. Source? my whole apartment building is a big concrete shell ( only columns and floors, covered on the outside by bricks. every single other inner wall is Pladur/Durlock, be it single (bathrooms & normal rooms) or double ( kitchen/dining room walls that touch with the nighbors). At worst you'd need to go trough 2.8cm of Pladur/Durlock + a 1.1mm aluminium structural vertical joint that is sometimes used to hang stuff up ( like the shower head's support). I bet most commercial hunting guns can do that easily, so for an assasin's high-cal pistol would be an easy task. ]
[Question] [ I need a way to send messages that can only be viewed once, and then become permanently unreadable (physical media destroyed, encrypted, any method as long as the message cannot be feasibly recovered by anyone). How can this be accomplished? UPDATE: This is happening in a world with roughly the same technology level as us. The messenger and recipient both understand the secret nature of these messages. [Answer] There's lots of physical solutions, but every one of them has some fatal flaw. There's information theoretic and physics based reasons why its really tricky to make something which can be read once, but only once. The best solution is used in the US government today. It's called "EYES ONLY." It's really simple. If I want to send a message to you, I write it on an EYES ONLY document, carry it to you, show it to you, then take it to a shredder to be disposed of. Beyond that, it's all just games. When you consider an opponent that is willing to mill the layers off a smart card and attach wires, guided by an electron scanning microscope, or an opponent willing to measure micro-amps of power consumption to attack your message, physical security just isn't what it used to be. [Answer] The fastest way is writing a message on edible paper (such as rice paper) using food colorant as ink. The reader finishes reading the message and immediately eats it. [Answer] # Take a quantum leap! The theoretically safe way to send a secret is to use quantum physics. See [Quantum key distribution](https://en.wikipedia.org/wiki/Quantum_key_distribution) Basically, you utilize the fact that a quantum state cannot be measured without being distorted. So if you encrypt your message in quantum states, as soon as the recipient reads (measures) it, it will become distorted gibberish. This means a tech level slightly above current, but no magic or alien physics required. [Answer] Back in the distant past, movies weren't rented off the internet via Netflix or iTunes, they were rented via physical media. In those ancient times, you walked into a shop, picked some movies off the shelf, went up to the counter, and handed over some money after agreeing to return the media on a given date (or be charged late fees). This is a model for the young people today to understand, pretty much like I struggle with the idea of my grandparents having to boil water on a large wood stove for a bath, but I digress. The point of it was that during those times, there was an experiment in certain quarters for a rental model that didn't involve returning the media. What they did was put kiosks out where you could walk up, 'rent' a movie which would trigger you receiving a disposable DVD of the movie. Why disposable? Well the idea was that the DVD was sealed in a black plastic bag with the name of the movie on it. The moment you opened the bag, the DVD was exposed to light, and there was a photosensitive pigment in the plastic of the disk that permanently turned the plastic in the disc opaque, meaning that the dye in the burnable disc couldn't be seen by the DVD player anymore. This took around 24-48 hrs to happen. It didn't take off because of several concerns, but mostly digital distribution coming on line. The thing is, this kind of pigment system could allow people to watch a DVD once, and then it wipe itself. If you had the pigment actually triggered by the DVD laser for instance, it could wipe itself as it was read. You wouldn't be able to rewind if you missed something, but it would certainly meet your brief. On top of that, this kind of pigmentation triggering wouldn't mean that you're restricted to specific machines to play the message; in theory, you'd be able to play it pretty much anywhere. [Answer] ### Pyrophoricity Write the message using [pyrophoric substances](https://en.wikipedia.org/wiki/Pyrophoricity) which ignite upon contact with air. Do the writing inside a box filled with an inert gas and seal it in an opaque & impermeable substance - or perhaps rolled up in a sealed glass bottle. The recipient opens it up and has a few seconds to read the message before it spontaneously combusts. No matches required. [Answer] # Cryptography geek-out Short answer: cannot be done, in the strictest sense of information theory. Long answer: okay, so it can be done... but there are a few requirements that depend on humans behaving correctly (which is always the biggest weakness of any "secure" system). ## [The players](https://en.wikipedia.org/wiki/Alice_and_Bob) * Alice, head of the organisation known as The Organisation * Bob, works for Alice out in the field, and is expecting a message from her * Carol, works for Alice as her communications technician * Eve, works for The Others, and really wants to get her hands on Alice's message to Bob ## The premise * Alice and Bob are not in the same location * Alice needs to get a message to Bob * Alice needs that this message is read/heard/viewed only once by Bob * Alice needs that Eve does not get hold of the message * Carol is the one that provides Alice with the tech needed to get the message to Bob ## The requirements * Alice and Bob have the secrecy of the message as their priority. * Carol is incorruptible. If Carol is in any way compromised, this makes the system she has set up for Alice compromised as well. Carol must be perfectly trustworthy. * Bob does not record/copy the message, nor does he talk in his sleep, nor does he give in to any kind of [method aimed at extracting the message from him](https://xkcd.com/538/). * The message can be seen/heard/viewed only by Bob. Do not use leaky headphones Bob... Eve can hear you. * Eve cannot intercept the message before Bob gets it. This of course means that the system that Carol has set up must be perfectly secure, and also that the incorruptibility requirement extends to all couriers that Carol employs. * Bob needs to follow his message extraction protocol perfectly. [Iff](https://en.wikipedia.org/wiki/If_and_only_if) we have achieved all this, then the question becomes mundane. A few possible methods... * Carol created edible paper. Bob is required to eat the paper after reading. Mmm.... chocolate flavour... nice one Carol. (See also Christmas Snow's answer below) * Carol has set up a secure phone line that cannot be overheard (a [one-time pad](https://en.wikipedia.org/wiki/One-time_pad) protocol solves that easily). Alice states the message plainly to Bob. This same goes for any kind of service that streams the message to Bob. * Carol has reprogrammed an MP3 player so that for every byte of audio it reads from its memory, it erases that byte through secure methods (i.e. overwrites it a thousand times with random data). By the time Bob hears that corresponding byte, it is already gone. [Answer] I'm assuming that you mean a read-once transmission medium that ensures no trace of the message is left behind once it is read. I'm also assuming that we are not dealing with in-transport security here, so that it's safe to assume that the message has been safely delivered to the recipient. So that the only requirement is that the recipient or anyone else can't provide or accidentally leave behind any evidence of the message content. Note that it's not possible to prevent the recipient (or a last minute eavesdropper) from copying the content as it is read. At least with modern technology. Any terminal delivery mechanism intended to transfer the message from the transport medium to the recipient's brain (e.g. audio playback or letters on a page) can reliably be captured by technological means (audio recording, photography) as it is being delivered. Even the signal from something esoteric like a direct cranial stimulation device can be recorded and used to deduce the message contents. So let's try to ensure that a message can't be extracted from the original delivery medium (or what's left of it) after it has been read, not before, and certainly not "as" it is being read. Unfortunately, our current understanding of information tells us that you cannot actually destroy information, as every current state of the universe depends on every past state, and given enough information about the current state, you can always trace it back into a past one. The only known way to really get rid of it is to chuck it into a black hole, and even then, you probably only send it elsewhere on a one-way trip. But that is probably more than good enough, so that's the principle to adopt. ## The principle of good enough You can't make it impossible, but you can make it practically hard enough so that it is no longer worth it to try to reconstruct the message from the remains of the medium. Let's think of two somewhat accessible contemporary approaches that would make it hard enough so that it is much more (orders of magnitude) expensive in terms of time, money and effort to reconstruct a destroyed message than to package it in the self-destructing medium. ### Photography materials Photograph your message onto film and personally print it onto photographic paper in the darkroom. Do the developer bath properly but skip the fixer/stopper bath. Dry it as it is and seal it into a light-proof envelope. Once the recipient opens the envelope, they have a few seconds to a few minutes (depending on the paper grade and the amount of ambient light) to read the message, before the paper completely turns black. Reconstructing the message from this black paper would take a whole crew of graduate level chemistry researchers equipped with tunneling electron microscopes, looking for tiny traces of molecules being reshaped in slightly different environments. They could probably reconstruct a simple message with heuristics in about a couple of months of dedicated work. It would take a few times more effort to accurately reproduce something with precise numbers, like the coordinates of a secret installation. All assuming that the message wasn't encrypted in the first place. Besides, if they make a single mistake in their process, they could easily destroy all their progress, and make it even harder to get back on track. Don't forget to properly destroy your originals and negatives as well. And always encrypt your secret messages. If this kind of activity is common in your world, there could probably be some device like a polaroid camera that works on these principles. You take a photograph of whatever represents your message, and this device produces a special print in a light-sealed envelope. The contents chemically turn dark a few minutes after exposure to light. ### Deliberately defective computer memory By design, the bit (binary digit) circuitry that holds a single one or zero in computer memory gets reset every time it is read. This is normally counteracted by rewriting the read data onto the bit circuit every time it is read. A purpose built chip deliberately lacking this rewriting mechanism would practically become a read-once medium. A potential gotcha here is how to deliver the once-read binary data to a human. Displaying it on a screen requires additional processing and at the least holding it on some other memory in the form of pixel data. Either the whole device and software has to be of trusted design, or it could be compromised. A simpler way could be storing digital audio in the 1-bit 192kHz Super Audio CD format or something similar on the memory, which can be converted back into a sound signal with very simple analog circuitry, involving just a capacitor, amplifier and speaker. And the data would be gone as it is being played back. Looking for the traces of the data on the leftover chip would be a similar effort to deciphering the photographic approach, this time employing a different set of experts and their lab. If you encrypt the audio data, then you lose the ability to play it back directly on simple circuitry. You have to decrypt it first. Solution, there are dedicated chips for that as well. ### Extra combo: Special CD-R Let's combine the two ideas… You could also maybe record audio on a special hyper-sensitive rewritable CD, set up to be so sensitive that the pickup laser in the player mangles it beyond recognition while reading it. Such a sensitive CD will probably have to be transported in a sealed package as other ambient IR sources (like the sun) could easily damage it. This is all the better; if someone who doesn't know this intercepts and opens the package, they are left with just a thin circular piece of transparent plastic. The recipient will know better, and put the disc into the player in a dark room. [Answer] If you're sending a physical message, write it on flash paper (nitrocellulose) and set it on fire after reading. This paper burns so well that it doesn't even leave ash behind; there's literally nothing to recover the message from. If you're sending an electronic message, don't ever store it on a hard disk or similarly persistent medium. (This rules out most current communication protocols.) After reading it, turn the device off and wait for a few minutes; after this point, no real trace is left in RAM. [Answer] There are many physical and chemical processes that can theoretically be reversed but are basically impossible. This may be as simple as completely burning a note that had a message on it, or completely destroying a hard disk using etching acid. A fun tidbit is that RSA Laboratories generated the famous RSA Numbers for their [factoring challenge](https://en.wikipedia.org/wiki/RSA_Factoring_Challenge#cite_note-3) by generating them on a computer with no network connection of any kind and then destroying the hard drive. Another fun idea to think about is the [black hole information paradox](https://en.wikipedia.org/wiki/Black_hole_information_paradox). If physical information is permanently lost when dumped into a black hole, then it would be physically impossible by any means to ever retrieve the information. [Answer] ## Self-shredding audio tape The problem with written message is that anyone can photography or screenshoot it during the lapse of time it is displayed. An audio message will remain invisible to the eye, yet conveying the same amount of informations for the recipient. Of course, i'm thinking about Mission: Impossible for an audio device, but not the kind you listen in public with a loud speaker like in the earlier series: I think more of a plastic-casted device that cannot be opened without destroying its contents, with a magnetic tape that only plays when connected to a particular set of earpieces (that only the recipient has, acting as a physical key as well as a biometric one if you need). When the earpieces are in place, the magnetic tape begins to unfold, delivering the message to the recipient and the part that has just been heard goes into a small shredder (or a small burner), making a second listening impossible. Then when the message is about to end, an automatic system opens a small vial of acid, destroying any remaining parts. Then it burns, folds into a crumble of plastic and throws itself into another shredder (that explodes). Also, the message does not stop until it has been completely delivered, whether the recipient hears it or not. Kind of a Prophecy Record like in Harry Potter, in fact. [Answer] # Schwarzschild Compressors Let me introduce you to my new and revolutionary invention, the Schwarzschild compressor. This handy device, no larger than a small backpack, will compress whatever matter you put into it well below its Schwarzschild radius, causing it to collapse into a miniature black hole that will itself succumb immediately into a Hawking radiation decay. The device is built to withstand the energy release of the collapsing black hole. In fact, this is how the battery is charged to provide energy for the next use (complemented by negative matter decoupler). --- Alternatively, one can also use... # Antimessage Generator For a bargain price of $999.99 you can now purchase an Antimessage generator. It will take a physical carrier of a message, and generate the needed anti-matter to annihilate the message entirely. The resulting high energy photon released in the process can be used to charge your mobile phone, too! --- For a bargain price, and only today, you can get both a compact Schwarzschild compressor (compress up to 50 gram of matter!) and an Antimessage Generator (up to 20 grams) for only $2001! [Answer] Embed ink in wax layers, a few words at a time. A layer of opaque wax, print the last few words of your message on it, put the next layer of wax on, print the words just before, and so on until you get to the top layer: "Good Morning Mr. Phelps." Add more layers to the top and bottom if you don't want the salutation and closing to be visible. Embed fibers or other interlayer structure to the process and heat to the softening point to prevent delamination. The recipient scrapes off the wax, layer by layer, revealing a few words at a time. In order to get to the next words, he has to scrape off the previous words. [Answer] On some old (90s) mobile phones, you were able to send an SMS to screen memory. This would get delivered to the recipients phone and open automatically on the screen. If you pressed any buttons, it would disappear and go back to whatever was on the previous display. The message would not be saved anywhere. [Answer] # Just say it Pass the message verbally, either in person or via some encrypted communication channel. The sound waves hit the recipient's ear and dissipate moments later, making sure no one else can hear the message. [Answer] Snapchat video message should work. The only way to view it after sending it is to record it, which in reality could be done with any of the above suggestions as well and will always be a risk. [Answer] ## Distinguish the three cases This is a practical, real world problem that a lot of industries have tackled, and there is a vast amount of literature on the subject if you really want to dig deep. There are a lot of good answers here, but both the OP and most answers failed to clearly distinguish three cases which are important in practice: 1. The intended / first recipient cannot be trusted to play fair. In this case, as others have noted, the problem is impossible: there is no way to make it fundamentally impossible for the recipient to simply broadcast the message as he listens to it -- not even by quantum crypto methods. 2. The intended / first recipient is absolutely trustworthy and thoroughly competent. In this case, we flip all the way from "impossible" to "easy." There are a whole bunch of ways to destroy the medium so that it can never be recovered. 3. The intended / first recipient is not trying to break the system -- at least, not trying hard -- but either won't try to make it work, or is not competent to do so. This is the actually interesting case that applies in the real world. It is essentially what -- cough, spit -- [DRM](https://en.wikipedia.org/wiki/Digital_rights_management) is about. It can't be solved absolutely, but it can be made so that it is much easier for Bob to comply with the protocol than to casually cheat or accidentally screw up. The system will fail from time to time, but hopefully, you can keep your losses low. There are three basic principles to make type 3 work: * The system must be automatic, so it doesn't rely on Bob not being a doofus, or being totally honest. To break the system, he must actively attempt to break its technical measures, or co-operate in allowing a stranger to do so. * The system must have graceful failure, also known as lack of brittleness: Cracking one device only provides access to messages intended for that device. * Losses arising from breach of a device must accrue to its owner. Now, Bob has nothing to gain from cracking his device, or giving it to hostile parties. If you can meet these conditions, the problem may not be totally solved but it's good enough to make a living. [Answer] The issue with a lot of the methods above is that if the message is meant for eyes then it can be photographed instantly before it disappears or changes, and if it’s meant for ears it can be recorded or listened in on. The safest way to send a message that can only be read once is to add layers of complexity to each step to minimize the probability of it being copied or read by somebody else. You can do this by add multiple layers of encryption requiring several messages in order to learn the decryption in order to be read, each message sent on a different medium and having different methods of disappearing after being read like the above methods. The probability that somebody would anticipate ALL of those methods in succession and be able to copy it for evidence would be extremely unlikely. [Answer] Encrypt and encode the message in a laser beam, and bounce it off something deep in space such that it takes a couple hours to get back to Earth. The recipient has to know exactly when and from where the tight beam messages are coming to be able to intercept it. That would be a scheme that is shared between the two parties ahead of time. Once the message hits Earth, its gone forever. The process could technically be done with radio waves or perhaps microwaves as well, but lasers are cooler of course. [Answer] I remember a scene from one of the Mission Impossible movies. There was a pair of sunglasses which played an audio-file once someone puts them on. The audio-file was basically some guy explaining what Tom Cruises next mission is. At the end, the voice said that the sunglasses would explode in about 5 seconds. Just enough time for Tommy to get rid of the glasses. This method of course has one major flaw: Is the recipient of the message capable of disposing the glasses after getting the message? (without getting injured, without injuring someone, without getting noticed etc.) I don't know what your plan is, but this could work out for you. Another thing that some of todays messaging-apps do is deleting the messages a few seconds after the receiver was reading the message. If everything is working out as intended (The recipient is connected to the internet while reading the message and the app does send a signal to the sender after the message was read), this is technically a safe method. Those messages are usually encrypted in a way that only the sender and receiver can read these messages. No one in between who manages to capture the transferred data is capable of decrypting and reading the message. Anyway, there are is one flaw I could think of: *Could the recipient want* to keep a copy of the message?** The person could just take a screenshot or do a recording of the screen before the message deletes itself. Some apps do notice if a screenshot was taken and tell all participants if this happened. If this happens once, the sender knows that the recipient is not trustworthy and should not send any further messages. Before knowing if the recipient is trustworthy, the sender could split up the message in a few batches in a way that every batch alone does not make sense if someone was reading just that single part. After each part was read and deleted, the next part would be sent. But in that case, you might as well record the screen with another camera, so the app wouldn't notice. Every single safe systems major flaw are the people who operate them. [Answer] ## Method 1: Sand sculpture The message is drawn on a plate or pane of glass with fine black sand on a white sand background. Then a plane of glass is pressed down and the edges are sealed. To erase the message, simply separate the plates and the sand pours out onto the ground. ## Method 2: RAM Although RAM has been shown not to immediately lose its contents when power is cut, overwriting data in RAM erases the previous value for all practical purposes. A dedicated message-viewing device could be constructed that, maybe after authenticating the reader somehow, displayed the message on an LCD display then overwrote its own RAM and displayed garbage data on the LCD, and then potentially catching fire for good measure. For added security the entire message can be encrypted with a key known by Bob and a second "plausible deniability" message with a different key also be embedded in the device. ## Method 3: Spontaneous teleportation Ok, this requires teleportation technology to be discovered. However, essentially, the message is teleported away from Bob once he reads it to a secure location where it can be archived or destroyed. One way to achieve this is for Bob to carry a pocket teleporter with him, which has a built in magnifying lens viewer, then teleport the message into the teleporter to send it to him, and teleport it away once he has had sufficient time to read it. If it's the kind of "lock onto an object" type of teleportation technology (a la Star Trek) then the message could teleport itself away, or a remote teleporter could lock onto it and take it. ]
[Question] [ We've got a lord - the lord returned from a quest and has been absent for a few years. When he returns it is to a little coastal town just large enough to have a thin palisade that protects it from raiders. The lord returns with only a handful of riders, whereas none of them are knights. So there is no significant retinue to confirm his status. His signets are not recognized but not claimed to be faked either. (They think it is legit, they just don't believe he is the ruler of the given region.) The people on the countryside are illiterate, do not come to the castle a lot and do not care much for the concept of maps. How would a lord in this case, in a legal non-violent way (cannot bite the hand that feeds him), prove to his people that he is the rightful ruler of the region? [Answer] ## Start with your allies The power of a king ultimately relies upon others recognizing that power. Someone who has returned from a years-long quest will need to re-claim the throne which is somewhat similar to someone else claiming it from scratch. It will not happen automatically, and it may easily fail. Whoever reigned during these years can wish things to remain that way, and may have made extensive preparations to prevent a return. Thus, arriving "with only a handful riders, where as none of them are knights", then marching on to "a little coastal town" is a monumentally bad thing to do if you want to return as a king. This would happen only if the king was exceptionally careless (and if that's so, how he managed to remain king up until now?) or some extraordinary circumstances (shipwreck?) forced him to do so. A realistic arrival from such a quest will be a plan on how to 'arrive in force'. If you can't do it now, then the first priority is to obtain that force and retinue before claiming to the wide public that you've arrived. You need to start with powerful people that you believe will back your claim to the throne - all the lords that are your relatives, friends or who have a political interest in having you in the throne as opposed to the other most likely option. If possible, you'd go directly to them. If not, then you'd hide in disguise until you can be safe from your political enemies - for whom this situation is a wonderful option to get rid of you permanently with no consequences. [Answer] Written documents were rarely used to prove kingship, and in general peasants didn't argue with armed men. If a group of heavily armed people turned up at your village and one of them said they were a king you said "Yes your Majesty, how may we serve you your majesty" and then sent a runner off to whoever the most important local person was so that they could deal with it. A local noble would most likely be able to recognize the king, or if not then again they would offer them hospitality while they sent for someone who could. Keep in mind that pretending to be the King when you are not would be a capital offence, anyone trying this and getting caught would expect to be hunted down and exterminated once people found out. [Answer] There is also a much simpler answer: the ruler will look like a ruler, even without the signets and such. Then it just becomes a matter of whether or not they think this person is lying about being their ruler, which probably isn't a smart idea. To elaborate: In a settlement like the one you're describing, this lord and his party will very much seem higher in social rank than the town's inhabitants. I'm not talking about colorful flags or fanciful garb or anything theatrical like that; simply the having mounts and weapons and other accoutrements/supplies one might take along with them would say much about their social status. Thus, even if the townsfolk have doubts this person is Lord So-and-So, they'll almost certainly recognize that he must be someone of a higher social class, in which case it may not matter much to them either way. After all, what's the point of potentially risking the ire of your lord if you're not sure it isn't him? Is it worth the risk? So even if the town is uncertain, they'll still likely accept it. Also, I'm framing this entirely from the viewpoint of the small village you've described; in a larger settlement (like a city) there would be other factors in play. (Additional side-note, the language the ruler speaks would indicate to the town whether he were a foreigner or not.) [Answer] Other than having your face on the money and monuments, proof of reign is social: the King is supported by the Lords. If nobody recognises you as King, and you don't have an answer to "you and whose army" then you aren't. If you go away and don't write and aren't popular you may find someone else is king when you get back. (See in the history of the UK, William of Orange vs Charles Stuart and the "Pretenders" who were technically the legitimate monarchs but were exiled into France for Catholicism) [Answer] Tim B's answer is pretty realistic. Force is the true legitimation of power in a feudal society, our concept of legal authority is an anachronism. That said just because people are illiterate does not mean that they cannot recognize symbols of authority. In fact feudal societies often have dense symbolic systems for non-verbally conveying each individuals place. 1) Historically specific colors became associated with rulers. For example purple cloth is associated with kings and emperors due to the high expense of producing pre-modern purple dyes. While the people of the town might not know who their king/lord is should he appear clothed in a color associated with royalty, they are more likely to accept his claim. Perhaps the color is associated with a particular royal family or lineage. 2) Legal restrictions on clothing items, known as sumptuary laws, are often used in feudal societies to reinforce distinctions. While historically this was used to distinguish nobles from commoners, there is no reason that a specific cut of clothing couldn't be limited to members of the royal family. 3) Objects can also legitimate authority. In the Roman Republic the authority of a magistrate was indicated by the number of lictors (bodyguards essentially) who they had at their command. Each lictor carried a ceremonial axe which symbolized their ability to impose capitol punishments. Any number of similar items (beyond the signet rings mentioned in the question) might symbolize power. While no one in the town may have seen these objects before, if they are sufficiently distinct oral traditions or art may make them recognizable. 4) Oaths tend to be very important in illiterate societies because of the lack of external confirmation. Should taboos against oath-breaking be strong enough, perhaps buttressed by any number of superstitions, then a strong oath might be sufficient for establishing ones' identity. From a modern perspective none of these symbols may seem sufficient to prove someone's identity but the standards of evidence in an oral society are likely to be far lower than they are in a literate society. Therefore some combination of these symbols would likely help a lord or king to prove their identity at least until a higher authority (church leader, high noble etc.) could be consulted. [Answer] If the ruler cannot be physically recognised as such (and nobody recognises his signet or other trappings either), and isn't willing to use force, then basically he won't prove to some random village that he truly is their King, at least not to start with. Even if he looks the part, demonstrates his noble bearing, demonstrates to the illiterate local priest that he speaks some Latin, and so on, that merely proves he's a lord, not that he's their lord or the top man. However, in a feudal society there will people around the place who are able to make a better assessment. Sufficiently well-informed priests, magistrates, sheriffs, knights, lesser nobles and whatnot. They won't be immediately available out in the middle of nowhere, so the King in effect keeps saying "take me to your leader" until he hits someone who recognises him or his signet. In practice it won't normally be necessary to prove you're the King anyway, since travelling as an unknown noble without a retinue is still pretty good. Serfs might not drop everything and follow him when ordered, like they would if they knew who he was. So if he wants to take command of the local militia, and they don't believe who he is, then he just can't and that's the end of it. But they're going to be mindful of the possible consequences if their lord ever hears from this unknown lord that they mistreated him, so it's much safer to help him on his way than to assume he's a charismatic rogue and tell him to naff off. Realistically there won't be many images of the King in the whole kingdom that are of high enough quality to use as reference, and none in a small village. But for comedy purposes, pointing at a coin and then at your face might do it ;-) [Answer] In the middle-age, one very efficient way of sealing contracts (I remember my teacher telling me it was during the Hundred Years War, for the english bowmen) was to cut a sheet of paper in two with a very specific patern, and to give one part to the bowmen and the other to the lord. There was no way to fabricate a copy of the contract with the exact same patern, so the lord would know who were his men. I hope this will give you an idea ! [Answer] If the area includes more than just these village people, then the lord may pay for his bread and butter for a couple days while send one of his horsemen to his capital (or other large town) and call a few dignitaries who can prove his status to these lot. Furthermore, if the lord has visited this place before, at least the elderly people should be able to recognize him. [Answer] Back in the 70's, the sultan of Brunei, who was, at the time, the richest man in the world was shopping in Harrods. He spends tens of thousands of pounds and wished to charge it to his Amex card. The salesman was unsure and asked if he had any other means of identity. His bodyguard opened his wallet, took out a banknote, and held it up beside the sultan's face. Does your putative ruler have any coinage with him? ;-) [Answer] The classic order has been: 1) Appearance: Wear dress fancy enough to impress the locals. Sometimes simply having a sword and/or mount was impressive enough. If that doesn't work, 2) Appeal to religion. Claim you are their leader by God's mandate. If that doesn't work, fall back to what always has worked: 3) Start bashing in heads until their admit that you were their leader all along. [Answer] Two examples from "real" story-telling are Ulysses (Odyseus) and Richard the Lion-heart. Ulysses drew the bow only he could draw and killed all of the interlopers. Richard was recognized by his old and true retainers (and was accompanied by some who had quested with him.) When travelling a local lord left his affairs in the hands of his wife and relations. Any feudal lord will have many local connections of fealty and blood. There were signet rings and such that would count as proof for illiterate persons, even of high rank. ]
[Question] [ How would build a road system or transportation system that respected nature with the following constraints: * No paved roads or less than 10% paved roads * can’t use gasoline (oil) * allow nature to thrive and migrate with little to no impact * food and resources can be bussed in or grown locally to reduce transportation * it can involve new technology or possible new technology Why? I visited somewhere that has 8 lane highways in suburban areas. Eight lanes.... Where I grew up there were two lane or one lane roads. Even then you’d see roadkill daily. This suburb was completely transformed from its natural state. Something that the wild life may have depended on for survival. I think in the future we will have villages or forest garden like cities that are smaller with less travel and less harmful travel with respect to nature and plant and animal life. I've seen examples of this in many retro future artworks. But in some of those they still have roads that interrupt nature or flying cars. How would you solve this if this was your issue to solve? Update: to clarify, it would be ok to have some paved roads mostly outside of villages and towns. or have dirt roads or side walks. people might walk, bike, or some other transport much more locally. yes it might require a change in the way of life. [Answer] Mass transit and alternatives to cars There are many countries that are focused on cars. As I'm from the Netherlands it's easy to think about grabbing a bike. Every person/group of persons on a bike for short distances (which can still be quite a lot of km, depending on the person) will be a car less. The thing is that some countries, like the USA, can't imagine going without cars. An example is from a channel I watched called "notjustbikes" on youtube. It stated that small shops inside urban areas is for them unimaginable. Their lives revolve around big one time pickups at huge shops, all by car. In contrast there are many counties where you can walk to a shop for daily groceries, removing most of the shopping by car. This is but one example, but a lot of reduction of traffic can be gained by a different mindset in planning and the populace. Having most commodities like work, shopping and relaxation easily reachable by foot or bike will reduce the cars by a huge margin. We're not there yet. Cars have been planted in many brains as a flexible and easy transport that can get you anywhere. In the USA you take a plane or a car to another state. Why? Because a long bus ride is horrible, trains are barely existent and there are no other alternatives. However, if you invest more into other transport like busses, trains or other instead of cars, they become more viable. Multiple people in a vehicle reduces the amount of vehicles on the road. Not all vehicles even need a paved road. Would you take the car if you can't park and there is a cheap, fast and easy train connection? Would you take the car if you're only allowed 50 maximum on not well maintained roads while beautiful well maintained mass transit is available? It is again partly a mind problem, but the message is simple. If there are better, faster and cheaper alternatives to cars, they will use them. Removing most if not all cars will allow you to reduce the road network. Simple as that. In addition, many mass transit examples can use electricity, which can be created with nuclear, tidle, wind, solar and other green alternatives to fossil fuel. You can immediately change from gas to hydrogen, which can be put into cars as a consumable fuel and be produced from (excess) electricity. This can be both burned (for example to cook) and used to directly make electricity in special cells. I'm thinking that we can't reduce it to 10% of the original. You still need some trucks to deliver things at the shops and such. But there we see the problem! My mindset can't think without trucks for the shops. But a full change in this mindset can solve this. Maybe there are solutions where it is passed on automated rails underground to each shop from a railway distribution center. Maybe you use a fleet of cargo bikes from a smaller distribution center instead! There are options, but we need a new extensive infrastructure and mindset to make it happen. There are multiple combinations of options for this, so no single answer. There is also some bonus points for growing locally. Using a mandated amount of roof space for growing food can already make a huge impact. Furthermore you can have more green where you grow these things. If people get a mindset where things like permaculture (round the year mixed food production. Work itensive but little land produces more) are commonplace, you can reach such targets quite quickly. [Answer] Frame challenge. Your complaint is about suburbs not roads. Suburbs are horribly unsustainable, they are the least desirable type of living in terms of environmental impact. Suburbs can't even support their own infrastructure monetarily. Suburbs maximize the local environmental impact of humans and fall pretty high on the overall impact. Suburbs also maximize the amount of roads. Suburbs are crap you want to eliminate them. So what do you do. Urbanize: people living in cities give the least environmental impact per person and and can financially support itself. Concentrate all the things you don't want in as small an area as possible. You don't want smaller cities; you want bigger ones. The smaller the city, the more of them you need. But you want urban cities not suburbs. But how do people get around? Sidewalks and rail. Rail is a lot better than cars on roads for the environment. It kills far fewer animals because the traffic is spaced out so there is plenty of time with nothing on the line so animals can cross. Even busses and trolley can have a huge benefit. Build many urban streets underground, minimize the impact on nature by moving it way from nature. More and more, so called "carless" cities are coming into the public mind. Here is an image from a planned city that may be helpful for getting a rough idea. [![enter image description here](https://i.stack.imgur.com/o3kat.png)](https://i.stack.imgur.com/o3kat.png) Note the car and truck travel is basically limited to the middle layer with train on the lowest layer. As a side benefit, this make AI driven vehicles much much easier. A good city planner can still leave natural corridors and parks, or convert existing roads into them while minimizing the foot print of the city. Note the big downside of this is your city needs to invest is some intense storm water management systems. But what do you do with the rural areas? Again use rail whenever possible. Public transport like buses are also a big help. The fewer vehicles, the fewer dead animals and the smaller the roads need to be. You will need to pave some roads, the more traffic there is the more paving will help, this is good for the environment too, pavement is the most recycled material on the planet. Rural areas are fairly low impact on wildlife, honestly the farming has a much bigger impact. You want paved roads. You want paved roads. Any other alterative results in far more environmental impact. Let's be clear: animals get killed on roads because they can just walk across them. Paving the road does not make this any worse. Not paving them just makes the road shittier which puts more traffic on the few paved roads (meaning they have to be bigger). You want almost all your public roads paved. You will never eliminate roads, animals make roads just by walking over the same ground over and over. Paving a road can actually help keep animals off a road by eliminating cover, animals don't want to stand around in the open with no cover and no food. More importantly you want to wall off your larger roads and build wildlife corridors over or under them. this minimizes the number of animals on the road. Animals are not that stupid. If there is a path to avoid traffic, most will take it. [![enter image description here](https://i.stack.imgur.com/kjIm3.jpg)](https://i.stack.imgur.com/kjIm3.jpg) Depending on how fictitious you want to go, these corridors can get wider and more numerous until you essentially have all long distance roads underground. Side note: Food is only a small fraction of the goods that need to be moved. Also you don't want only local food, you want local food when local is possible. So you still need a massive transportation network, the ideal is to centralize and concentrate it as much as possible. Of course you can't concentrate it too much or you risk people getting cut off by natural disasters. Eliminating gasoline just means switching to mostly electric and some biofuel. Public transport is extremely good at switching to these. Many already use them. [Answer] Just the other day I was reading an history atlas about the city where I live. The chapter I was reading mentioned that the works for the first paved road from the town to the local administrative center started somewhere in 1700 and went on for about a century, among lack of funding, quarrels with other towns on the route of the road and wars. The main complaint at that time was coming from merchants, who had to get an additional pull of horses when the paved road ended and they needed to transport their goods on the natural roads. Guess how where the natural roads made? Mud in rainy weather, sand in dry weather. When the town folks would have to rely on local production for their sustenance the population was about 300 people, and that was for good part of the first 500 years of existence of the town. In Italian there is a saying that goes "wanting the full jar and the drunken wife" for addressing two mutual conflicting goals, and this is what you are aiming for: natural unpaved roads are a very poor choice for transportation, as already the roman empire had understood. If you want to limit roadkills and allow animals to move despite the barrier represented by the road you could go with something like the "nature bridges" built in the Netherlands, where a bridge is built over highways to allow animals crossing them with no danger of being hit, like the one you see below. [![enter image description here](https://i.stack.imgur.com/kIqQG.jpg)](https://i.stack.imgur.com/kIqQG.jpg) One can also lay pipes of suitable diameter below the roads and use fences to allow safe crossing to wildlife, which is something I have seen on Dutch local roads, too. In the screencap below you see the fences and an intermediate well for an underground animal crossing, in a road that cuts through a forested area. [![enter image description here](https://i.stack.imgur.com/629oa.jpg)](https://i.stack.imgur.com/629oa.jpg) But as you can see those systems use paved roads, because those are way better than unpaved roads for transportation. [Answer] Maglev (Trains) I'm surprised nobody has come across [Maglev railways](https://en.wikipedia.org/wiki/Maglev) as a suitable alternative to vehicular transport, being not only significantly faster and cleaner\, but also having significantly less moving parts. To move goods from New York to Los Angeles would take [only 7 hours](https://www.energy.gov/articles/how-maglev-works) and would require only a single "railway" of space, minimizing damage to habitats and wildlife. As for the wildlife, [the real-world application has already been implemented](https://www.boredpanda.com/turtle-tunnel-train-track-safety-japan-railways/?utm_source=duckduckgo&utm_medium=referral&utm_campaign=organic) and is similar to a number of the answers regarding nature bridges and the like. \Now a key part of Maglev is that it uses high currents of electricity, and that electricity must be generated in some fashion. In today's world, [a good portion of the generated power is from fossil fuels](https://www.quora.com/Why-dont-we-use-maglev-engine-vehicles-instead-of-fuel-engine-vehicles-that-cause-pollution?share=1), however this is not necessary should nuclear/solar/wind power be the prevalent form of energy generation in your world. Done correctly this along with [MRT (Mass Rapid Transit)](https://en.wikipedia.org/wiki/Rapid_transit) can be situated underground entirely, avoiding a good number of the headaches of animals depending on the depth of the railway. [Answer] Canals. <https://westerncivguides.umwblogs.org/2013/12/03/britains-canal-system/> [![canals](https://i.stack.imgur.com/bNumj.gif)](https://i.stack.imgur.com/bNumj.gif) Before there was tech to make those 2, the British built many canals and they worked great. As regards efficiency canals are third best to railways and roads. If you prohibit paving and oil then canals are again #1. They are a proven method of inland travel and suitable for individual travelers or large bargeloads. The idea of updating canals with modern tech is pretty sweet - battery powered boats or steampowered woodburners. As regards keeping the airclean I again ponder my scheme for the riverwater exhaust bong... [Answer] You seem to assume that 10% unpaved is a requirement to achieving your goal. However your 8-lane highway would still be dangerous to animal life if it was unpaved. So let me offer you an alternative: bridging all your roads. Most of the time questions like these you would look for digging underneath and building tunnels, but you don't seem to care about existing infrastructure. So if you "simply" build many tunnels over the highway instead of digging into the ground you can create large continuous stretches of covered road. The top of this tunnel can be covered with ground and seeded to stop erosion. This is similar to the Ecoducts that L.Dutch refers to. The effectiveness of such ecoducts is undeniable, even though the ecoduct isn't that broad it can be silent enough there for animals to lie down and sleep. You have much longer stretches, if not almost all roads covered. Alternatively you could build buildings on top. Naturally like all tunnels there will be a need for periodic ventilation shafts up out of the ground, although since the road is covered rather than dug in you can poke shafts sideways. To reduce gasoline you can use powerlines on the roof of your tunnel structure. This is something already considered for trucks: <https://www.cleanenergywire.org/factsheets/electric-highways-offer-most-efficient-path-decarbonise-trucks> Your vehicles could have a relatively small battery to save weight and simply draw most of their energy directly from the powerlines, only replenishing their batteries whenever they needed to shift lanes or disconnect from the powerlines for other reasons. [Answer] You want DENSITY. Lets say we have 10 million people to house. You are right, spreading them out over some huge suburban concrete-scape with 8-lane highways connecting it all together is going to be a big problem for any wildlife in the place you are building. One way to reduce the impact is to concentrate it. Lets say those same 10 million people lived in an environment like Manhattan. Skyscrapers, underground trains, sidewalks, and yes some roads too. By focusing all our people into this small area we can leave the rest of the space empty. So maybe 90% of our area has no roads at all (or almost none). This way nature gets its untamed wilderness, and the people get the convenience of high quality roads and pavements where they are. Obviously people like living near nature. But at least in terms of environmentalism it would probably be better if they didn't. [Answer] # Monorail Even though maglev was mentioned, a monorail is the core idea. The [Shweeb](https://en.wikipedia.org/wiki/Shweeb) is hanging monorail cars good for personal rapid transit: [![enter image description here](https://i.stack.imgur.com/Z4XRx.png)](https://i.stack.imgur.com/Z4XRx.png) The inventor made an entertainment [attraction](https://www.shweeb.co.nz/) of them in New Zealand. [![enter image description here](https://i.stack.imgur.com/Ju47d.jpg)](https://i.stack.imgur.com/Ju47d.jpg) The tops could use [maglev trains](https://simple.wikipedia.org/wiki/Maglev_train) for larger, heavier, cargo and longer distance routes. [![enter image description here](https://i.stack.imgur.com/UQrwh.jpg)](https://i.stack.imgur.com/UQrwh.jpg) Unlike how the picture shows, it would disrupt ecosystems less if they were built higher up above tree lines. Although, flying animals will be disturbed, especially certain breeds of birds. [Answer] A key issue is geography which is not addressed in the initial question. E.G. Mountainous/hilly environments vs dry desert plains or low lying coastal or river flood plains and marshes etc. Different environments would require different solutions. That said I note the following; General Point; 1. Paved roads are, in most cases a more suitable road surface than unpaved roads. Apart from the safety issues they eliminate soil erosion and runoff/silting of local water systems due to heavy rain or flooding etc. Plus they require less maintenance. This is important for heavily used roads because energy and other resources are wasted on both the repairs and the road diversions put in place during repair which lengthen trip times/routes. So I would still go with paved roads as the better long term option. Specific points. 2. Proper waste water run-off infrastructure. Where possible waste water needs to be directed from the gutter into well maintained settling ponds. Ideally before leaving the ponds most of the water should undergo at least basic filtration to remove heavy metals and other contaminants. Depending on local need it can then be; A) Fed into commercial filtration plants for additional cleaning prior to being recycled for human use or; B) Otherwise diverted into local water courses. 3. Harvesting energy from main roads. Systems have been designed which extract electricity via photovoltaic or piezoelectric tiling. It would be too expensive/impractical to pave entire networks with these system but the best/most productive sections could be. E.g. busy intersections for piezoelectric or exposed sunny stretches for photovoltaic. 4. Use environmentally friendly materials in road bases and cement. Use of recycled or green materials as substitutes for (or to reduce the use of ) traditional materials.Glass recycled plastic fibers etc can increase the durability and ductile strength etc of cement and or road bases. 5. Use of green power for street lighting (every little bit helps). 6. Use of road verges and medium strips as green zones for selected local plants, specifically native wildflowers and grasses etc so that they provide refuges for local insect populations and increase the diversity of food sources for pollinators. 7. Mandatory reintroduction of hedgerows on local rural and semi-rural roadways as ecological refuges for animals insects and plants. 8. Mandate local governments to 'green' local streets (where practicable) using sidewalks planted with native species - and not just trees but particularly local flowering plants and grasses. 9. Construction of regular animal overpasses or tunnels as mandated by geography on highways. Greened walkways with associated fencing to divert migratory animals along these pathways. Include overhead rope ways for arboreal species. 10. Fencing on local roads at environmentally sensitive 'choke points' to prevent/minimize road kills. 11. Plant shade trees in cities along along all main roads to help cool green the local environment in conjunction with roof top or vertical lawns and gardens and green spaces etc. 12. Diversion of all possible heavy transport off roads and onto rail freight. 13. Reduce demand for roads by having well designed and subsidized mass transit systems - railways, subways, buses and trip share/taxi services. 14. Plan and design roads networks in advance to avoid or at least minimize damage to key local environments e.g. wetlands. There are probably more I could think of but these cover the basics I think, noting of course that not all of these suggestions would realistically be practicable or affordable at all locations across the entire the road network. The most likely outcome being a mix and match strategy based on a cost benefit analysis of local geography and traffic demands etc. [Answer] I'd just lift the whole road some 4-6 meters into the air, making them essentially into bridges across the country, allowing vegetation to grow under them and making it all but impossible for animals to get on the road (except maybe birds and squirrels?). This coupled with gasless cars (either electric or hydrogen-powered) basically nullifies the negative effects a road can have on the local nature, leaving only noise pollution and light pollution issues, which are already reduced by lifting the road and can be diminished further. It is more expensive to build, obviously, but caring about the environment is more expensive by default than just going the path of the least resistance of not caring about consequences. [Answer] Living Tree Bridge Not exactly an answer that you will want but a little reference for your help. A living root bridge is a type of simple suspension bridge formed of living plant roots by tree shaping. They are common in the southern part of the Northeast Indian state of Meghalaya. They take decades to build but stay strong for hundreds of years. Refer to these for details: <https://en.wikipedia.org/wiki/Living_root_bridge> <https://www.nationalgeographic.com/history/article/india-living-tree-bridges-stand-hundreds-years> <https://www.bbc.com/news/av/world-asia-india-39364422> [![enter image description here](https://i.stack.imgur.com/cLZCd.jpg)](https://i.stack.imgur.com/cLZCd.jpg) [Answer] ## Underground Say goodbye to your snowplows - these roads keep a constant temperature year round. The air is locally processed to remove pollutants, and recharged with oxygen in one of the many small underground nature preserves for threatened species before it is returned to the roadway. The terrible noise of highways infesting the countryside is a thing of the past. ## No roads needed Cars have been retrofitted with wheels that can extend metal projections that can be controllably bent at many joints along their length and automatically fluff out into origami pads that precisely match the calculated contours of the ground just before they meet it. The extension and retraction of these projections is halted by regenerative braking so that they have little real energy cost. The car can seem to coast for long trips over bog and woodland, using sophisticated imaging from itself and stored map images to plot out a path that goes between the trees where they are sparse, or climbs right up over the canopy when they are not. Maximal efforts are taken to capture pollution and noise before they leave the vehicle. The machine still has more of a footprint than if it were underground, but if done well they may be quite light. ## Roads? Where we're going... No, we can't unleash jet turbines - that would be awful. Instead our Necromancers have something better -- gossamer strands of graphene, each of which is tethered to a mighty bird, each of which is genetically engineered and electronically modified to provide maximum lift for minimum "fuel" while obeying every computer-generated command to the smallest detail. Our bird wagons sail the sky like a flock of passenger pigeons (probably they actually are passenger pigeons - Necromancers say the dead should surrender their rights in favor of gratitude). It is almost natural when they darken the skies with the flow of our traffic. When their voyage is done, they can detether themselves and are free to fly about almost in accordance with natural instincts ... within limits. The system guides them to places where nuts and foodstuffs are laid out for them, to make up for lost time in foraging. [Answer] TLDR: Solution An AI driven network of flying electric drone cargo and passenger vehicles completely removing the need for vehicles on the ground. Two Options Go up or go down. I see tons of answers about down. Roads in the ground (IE: The Boring Company). I see some answers about going up slightly (IE: elevated highways like this one <https://www.youtube.com/watch?v=-IRkRZvE8LM> ) Up!! Single, multi or dense passenger drones and cargo drones of equally varying sizes. Single person Possible single passenger drone in the near future from Cadillac: [![enter image description here](https://i.stack.imgur.com/KLw9F.png)](https://i.stack.imgur.com/KLw9F.png) <https://www.youtube.com/watch?v=h8DeBdp1fxY&t=82s> Passenger Drones Multiple passenger drone concepts last year: <https://www.youtube.com/watch?v=pv4A9IFm-7I> more than moving people Cargo Drones from a company: <https://evtol.com/news/pipistrel-launches-nuuva-hybrid-cargo-drones/> <https://youtu.be/l-2O1_Wd06E> [![enter image description here](https://i.stack.imgur.com/0Vmbi.png)](https://i.stack.imgur.com/0Vmbi.png) AI Controlled <https://www.youtube.com/watch?v=LvYNHSf7FbI> <https://www.forbes.com/sites/johnkoetsier/2020/05/06/machine-first-world-getting-drones-robots-self-driving-cars-and-ai-driven-systems-to-work-together/?sh=288ad22b1899> > > “We are entering .. an era of the autonomous economy,” Kumardev told > me in a recent episode of the TechFirst podcast. “And what that > effectively means is that today we have humans-first in most jobs and > most sort of processes, whether that’s industrial, or retail, or even > food delivery ... medical delivery … and my vision is that we are > going to move to a world where machines-first.” > > > Get in a vehicle and it moves you to where you need to be... up, over and down. no roads needed. Wrap up We aren't far from having this technology. All we need is slightly better computers, a little better programming/AI, batteries with a bit more density on a lighter footprint... All you have right there. Vehicles that can shuffle individuals or groups (passenger drone busses? cargo haulers? Long range transports?) and/or cargo between without ever touching ground. When the technology comes together, I honestly feel as if we aren't are off from having the basics to have this in our lifetimes - laws and politics not withstanding. <https://www.scientificamerican.com/article/forget-flying-cars-passenger-drones-may-be-hovering-soon-at-a-location-near-you/> > > The dream of the flying car could come down to earth before it gets > off the ground. Rising in its place: a network of self-flying drones > big enough to ferry individual commuters around town. That’s the > future envisioned by several start-ups that are developing so-called > “passenger drones,” which could shrink commute times from hours to > minutes. > > > In a few years, these things will make the building blocks for what you envision and might become reality in the lifetime of some younger people alive today. [Answer] Your premise is a bit off kilter. Paved roads are a must for any kind of large community of individual ground travelers. Bare ground is the enemy of travelers, especially heavy transport. Heavy transport is required for any advanced commerce; you must be able to move a sufficiently large quantity of goods to produce value (profit) and to support large population centers. Rail lines and magic tree bridges will not get your refrigerator from the market to your house. 10% road coverage will cover some home (and work) to trunk lines but is not enough. Eight lane highways exist because they are used to capacity at peak times. Oil is 100% required for advanced machinery. We don't need to burn it, but we 100% need it for plastic and lubricants. If you murdered 90% or more of living humans, then they could live in happy communes and all grow organic food. Of course, they would have to give up all advancements post (about) 1865. Travel is the means by which ideas propagate. If you limit travel to the rich, then your society will stagnate and die out. The other side of stagnation is war; as smaller communities grow they need more resources and they will fight over them. Also, in the land where "most" villages have abandoned modern tech in favor of "tree hugging", the advanced cities will rule and easily enslave or obliterate the non-techs. [Answer] # High density, car-free zones, and public transport There are many cities in the world who have solved, or are trying to solve this problem. The three main approaches I have seen which are successful are increasing density, and creating car-free areas, and public transport. The main reason people need personal vehicles is to get places. If everything is within walking distance, the need for cars goes way down. High rise cities do this great, you can have a skyscraper with a convenience store or supermarket on the ground floor, and a shopping district every few blocks. With mixed use spaces, people don't even have to travel far for work as there may be offices in their building or nearby. Modern technology can make way for centralizing industry too. For example vertical farms can be built within cities, eliminating the need to truck goods from afar. Having mixed zoning means that products don't have to travel as far to get from where they are produced and manufactured to where they are bought, and then back to the customer's residence. When people do have to travel far, it's convenient to have a good public transport network to support them. Trains are most efficient, and subways hide under the ground so you don't need streets. Using boats for external connections also reduces the need for roads. Many cities have instituted car free areas too. This means streets don't have to be as wide, and density can be further increased. A dense car-free core supported by public transport or boats has proven to be great for reducing road systems. [Answer] In general people tend to concentrate in large areas. That's because there is more work in large cities, and especially large population allow to turn the job that would be part time in a small town into full time (for example, specialist shops that would not find enough clients in small towns). And the number of people is constantly growing, and needs to grow for our economic system to functions as it is based on constant growth (fe. China had to drop single child policy as they faced a rapidly aging society that would eventually lack working people needed to support the old). So, unfortunately, I cant see your village-based settlement model as something that could happen. As for the transport system you want, there are only two options: either you move transport entirely underground or into the air as unpaved roads just can't carry the amount of traffic necessary for modern society. The air option include various train lines that are on pylons over the ground (maglev, tube), as those allow plants and animals to return when the construction is finished. Another option would obviously be Star Trek style teleporters. [Answer] > > (...) with the following constraints: > > > * No paved roads or less than 10% paved roads > * can't use gasoline (oil) > * allow nature to thrive and migrate with little to no impact > * food and resources can be bussed in or grown locally to reduce transportation > * it can involve new technology or possible new technology > > > I see no specification for mass transit, efficiency, short travel times, low costs etc. So pulling the devil advocate here, do it like the indigenous people of the Amazon rainforest did and enforce people transporting stuff on their backs or on stone-age wooden boats. Food was grown or hunted locally and there was no pavement. Humankind managed it quite well before bronze even became a thing. We were more green back then too. Might as well take a page from Ötzi. [Answer] You have not mentioned population size, population density, or if this is an add-on solution to our current society or if it was always thus. Really, we had the solution that met all of your criteria - the horse. It: did not need paved roads; respected nature; and was flexible enough to transport food and resources. It was an excellent solution for the population at the time. Unfortunately, it had three drawbacks. The first was pollution (waste had to be collected from the streets). The second was the ability to repair. Although horses were somewhat self-repairing, major damage resulted in the horse simply being abandoned where it demised. The third was feeding it. The feed had to be brought to where the horse was staying, the horse was not taken to where the fuel is. So, one solution would have been for the society to breed a house-trained and meat-eating horse-substitute animal, sort of like a very large cat-dog-horse hybrid. The problems of waste and feed would be greatly reduced. Horses, because they get their energy primarily from hay and such, have to consume great quantities of it, with the resultant great quantities of waste. Animals that are higher up in the food chain like dogs and cats require less volume of feed. With cats, because of their preference for liter boxes, the depositing of their waste is greatly confined and controlled. Give them paws instead of hooves, and with the much larger bearing surface they have much greater stability in mud and inclement weather. The obedience and versatility of dogs is generally well known. And, really, the animal would definitely not have to be as large as a horse. Ponies and donkeys, although much smaller than horses, can adequately carry a full-grown human. Some breeds of dogs are already large enough to carry children, and lions have no difficulty strength-wise in carrying adult riders. Roads, when needed, could be constructed out of rocks and gravel, or cobblestone, or even wood and logs, instead of super-smooth concrete and asphalt. Much easier to build and repair, and the wear-and-tear on them would be far less from a 300 pound four-legged animal with paws than a two-ton automobile. So let's imagine a society that had developed such an animal. Would the gasoline IC engine have provided a great improvement? A large can of food a day, waste collected in barrels weekly the way we collect compostable green waste, and a really good pet to boost? No need for stables, they live in the house, or a good-size dog house would suffice. Now, think if Spot the dog-robot from Boston Dynamics. A natural evolution of this animal. Put a saddle device on it, and you have an excellent transportation solution. Better than a bicycle, it does not need a path. It can go up stairs, steep pathless hills, and in and out of doors. Using remote control or AI, it could deliver the passenger to their destination, then go off and park itself. We would not have the problem with 'automobile safety' and 'car accident trauma' we have today. Our current problems with clogged roads, large expanses of paved areas, atmospheric pollution, and such are pretty much all related to our adopting the gasoline IC engine in the first place over the horse, and thereafter defining our concept of transportation. We gave up four legs for four wheels. [Answer] The Conspiracy X tabletop RPG from Eden Studios has the Saurian race, who inhabited Earth in prehistoric times. The game asks the question, if there was this high-tech (interplanetary spaceflight capable) race on Earth then where are their remains? Where are their cities and roads and railways and powerlines? Why don't we have fossil remains of all their tech? It answers this by postulating that the Saurian scientists developed gravity technology very early. As a race, they had a strong ecological drive, so once they invented antigravity they went on a massive project of tearing up all their paved roads and railways. The remains of their onplanet technology is no longer around because of a nanomachine grey-goo disaster (which explains why mammals are the dominant race now). [Answer] Use [suspension railways][1]. If you want high output roads which don't impact the environment heavily, you need something that isn't gonna go over the ground. So, instead have a floating road. Cars and trucks and such that want to go to the city or the village are hooked up to a floating rail and moved in, using green solar or wind power or batteries. The quick dirty way to do this would be concrete pillars, but you could using future technology have specially grown and easily transplantable trees which could hold up the road. Advanced future technology which can turn glucose into electricity could use the tree's own energy reserves to power motors, reducing power requirements. Extremely heavy traffic would likely deplete the trees too much, but for light traffic you could have entirely green energy. [1]: <https://en.wikipedia.org/wiki/Suspension_railway> ]
[Question] [ The year: Sometime between 2025 and 2045. The place: A new high-end subdivision (or custom home showroom) near you. The sales pitch: > > This home is great for entertaining. It has a complete iKitchenᵀᴹ and iPantryᵀᴹ. The iKitchen can cook gourmet meals from scratch -- everything from appetizers to a complete Thanksgiving feast. It has thousands of recipes, including the complete Joy of iCookingᵀᴹ. And it cleans up after itself. It sanitizes all of the prep surfaces before and after preparing every meal. It loads the dishwasher automatically. It even puts away the dishes! > > > My question: How does it put away the dishes? What kinds of device(s) or attachment(s) does it use to put away the dishes? Where does it store the device(s) or attachment(s)? Does it need special cabinets or drawers to put the dishes in? Constraints: * By "dishes", I mean all of the cooking tools that are designed to be washed in a dishwasher, plus the plates and flatware used for serving the meal. * The device(s) or attachment(s) that put away the dishes need to be sanitized regularly, perhaps by washing them in the dishwasher. * The iKitchen equipment does not need to go outside of the kitchen/pantry/butler's pantry. (A "butler's pantry" is an old-fashioned space between a kitchen and a dining room, where food and dishes are transferred from the kitchen to the dining area. In many modern homes, a kitchen island or a side table in the dining room is used for this purpose.) * It is OK for the iKitchen to assume that dirty dishes will be brought back (probably by humans) from other rooms to a "dirty dish place". The "dirty dish place" might be a counter, or perhaps a convenient dishwasher rack. * The iKitchen will make sure that any "dishes" that the iKitchen dirties and keeps within the iKitchen get washed without human intervention. * Ignoring the cost of ordinary walls, floors, windows, and doors, the complete iKitchen and iPantry should not cost more than a new Tesla (roughly 40,000 - 100,000 U.S. Dollars, adjusted for non-electronics price inflation since 2015). * All products need to be covered by at least a 12-month parts-and-labor warranty when used for typical single-family residential purposes. The warranty can be provided by the manufacturer and/or the installation subcontractor. The warranty does not need to cover abuse. [Answer] One possibility is to avoid the problem entirely by making the place you store the dishes also be dishwashers. So you put dirty silverware in the silverware drawer, and clean silverware comes out. The drawer detects dirty silverware and washes them automatically. The cupboard where you store your plates and bowls also washes those plates and bowls if they are dirty. The cupboard where you store your pots and pans cupboard also scrubs and washes those pots and pans. If you take it a step further, you don't deal with the storage at all. You stick your dirty dishes in a machine. The machine washes them, sorts them, and stores them inside itself. Next time your kitchen makes a meal, it knows exactly what dishes you will need and the machine provides them for you. The washing, storage, and retrieval would all happen on belts behind-the-scenes. [Answer] Why wash anything? An improvement in the quality of biodegradable plastics means that you can throw out your cutlery and crockery at the end of every meal! You get more space in your kitchen for other stuff, because you don't need to waste space on all those cupboards full of plates that only get used a few times a day. But where do the utensils you need come from? They are 3D printed as your meal cooks, so your gourmet meal always comes with the right tools. You'll always have a steak knife with your steaks, sweetcorn forks with your sweetcorn, chopsticks with your Asian cuisine and eggcups for your dippy eggs. [This, minus the magic robot kitchen, and with clay instead of plastic, is what already happens every day today in Calcutta - tens of thousands of clay cups are made every day, sold full of tea, and then thrown in the gutter, where they disintegrate back into the soil.](http://news.bbc.co.uk/1/hi/programmes/from_our_own_correspondent/9385244.stm) [Answer] Within that time period, we should expect classic sci-fi robots to be a reality. The humanoid kitchen robot has hands like ours, a height and reach like us, so can use tools and work areas designed for us. It will use the pots and pans, the stove, the sink, etc. and asking how it puts dishes away is just a no-brainer. ![robot](https://www.popsci.com/sites/popsci.com/files/styles/large_1x_/public/import/2013/images/2010/04/1552967.jpeg) From [this article in Popular Science](https://www.popsci.com/gadgets/article/2010-04/dishbot-cleans-house-learns-live-uncertainty). > > YES, WE'VE LIVED IN THE ERA OF THE DISHWASHER FOR SOME TIME. BUT FOR THE TOUGHEST, GREASIEST PANS, CALL IN THE DISHBOT > > > But what if a robot, after a long dinner party, could bus the table and head to the sink? Now there's a relationship we can build on. Japan's HRP-2 humanoid 'bot, pictured here, has learned to do just that. > > > So that’s already real. See the linked article for a whole set of awesome photos. [Answer] I'm assuming your question is focused on the USA and maybe other first-world nations. There's some big cultural differences that would shift this question considerably. Home cooking is [becoming increasingly rare in the USA](https://www.washingtonpost.com/news/wonk/wp/2015/03/05/the-slow-death-of-the-home-cooked-meal/?utm_term=.ebfb3deff4bf). New homes don't always have ovens as the microwave suffices, and within cities, eating out for every meal has grown steadily more viable over the years. It can even be done healthily in big cities with more than just fast food restaurants. Price is a bit high but has been steadily falling for over a decade. Couple that with Uber/Lyft/TaskRabbit, etc -- in my city (one of those tech hubs) many (are we to most yet? No idea but it wouldn't surprise me) restaurants that used to be dine-in only couple with a delivery service. It honestly would not surprise me if by 2040, new homes stopped having kitchens, period. It will depend upon the level of delivery automation, but that's been moving along a lot faster than I had predicted just two years ago. If we do have kitchens, they may well be joint ventures with a whole subdivision, like the pool or park in an HOA. So, in summary... your "iPantry" will cost the same price as Amazon Prime does that year. And iKitchen will be the name of a neighborhood restaurant where you dine out (and given the lower case i, it may be a bit pricy). [Answer] Why not check with google - we already have concept for this. Kitchen would be behind glass, where robotic arms to all the job: <https://www.youtube.com/watch?v=A5wWL4pNeis> It is safe to assume it has an hole where it puts out dish with food and where you put back empty dish. Program can then recognise what it is (like plate, cup, fork, etc..) and move it to designated location in dishwasher and after it has been cleaned it can be moved to it's place. You could probably remove the glass from the picture and have those arm retractable, but you would still probably be restricted in having the preprogrammed type of kitchen items so it knows where it has to put it away. Also you could add 3D scanner for people to add new items and designate default locations for items so that robotic arms can pick it up later and put it away. [Answer] ## Fresh food, fresh dishes Why not go all the way and expect the kitchen to make new dishes and utensils for every meal? It can 3d-print them from a degradable material, customizing the shape for whatever best fits the meal. Yes, there's some waste involved, but the target audience of iKitchen can afford that. [Answer] First things first: All dishes must be ikitchen dishes and cookware. This is because the system will likely be built to handle specific weights and will be less likely to malfunction if dishes are a specific size and programmed to go into a specific place, sized for being put away there. All cabinets must be icabinets Within the cabinets will likely be outlines where the dishes go. If anyone puts a dish in the wrong place, the automated system will likely malfunction, or break a dish, because it doesn't expect something like, say, a glass to be where the dinner platters should be, the glass will likely get smashed. But more likely, dishes won't even be directly accessible by people, and might be just an automated system that puts dishes out (see the link in the bottom of this answer for a vid of how they might be stored.) Putting the Dishes Away 1) The best suggestion on here is simply that once the dishwasher is loaded, it is well-dried, then the entire dishwasher box is sent to a different area of the kitchen--which will be where you get the dishes from when you eat. The dish washer can below and will rotate up, using a gear system and the lower deck is the dirty dishes. 2) All the dishes are sent on a track behind the cabinets. Their weight and size tells the system where they will go. Putting things away, or even taking them out, can work like an [old fashioned jukebox placing records down](https://www.youtube.com/watch?v=Z0z2Bc-C79w). [Answer] > > It loads the dishwasher automatically. It even puts away the dishes! > > > This doesn't seem to match how iThings work. I would expect an iKitchen to have an order interface (maybe in a smart phone app or a tablet), a serving place, and a dirty dish return. Cupboards? Dishwasher? All hidden behind the simple interface. I wouldn't describe it as loading the dishwasher or putting away the dishes. You (or the server) put away the dishes in the dirty dish return. It processes the dishes. Consider > > Freshly cooked food comes out on sani-cleaned dishes. Dirty dishes go in the patented return and are cleaned and fully sanitized for you! All you provide is the hungry stomach. Just tell the iKitchen what you want, and it will handle everything else. Or choose one of our diet plans and we'll pick a tasty, nutritionally-balanced option for you! > > > That fits more with what I would expect from an iDevice: a simple interface that hides the complexity from the user. Dirty dishes go in one slot; clean dishes loaded with food come out another. You could even have a mobile device like a cart. Fresh food is on the top of the cart. Dirty dishes go on the bottom. It trundles around the kitchen table. People dump their dirty dishes and grab the next course when ready. It gathers more food and dumps off dirty dishes as needed. An android waiter might be a future alternative to the cart. [Answer] Well, this is already possible using today's technology and might even fall into your desired budged. Basically all you need classic industrial [robot arm](http://www.motoman.co.uk/en/products/robots/product-view/?tx_catalogrobot_pi1%5Buid%5D=444&cHash=9413ffe331cb5a65f75a767c1c59b7d9), which mounted on a [tracks](http://www.motoman.co.uk/en/products/rotating-base-and-tracks/product-view/?tx_catalogbasic_pi1%5Buid%5D=207&cHash=933c27f70ca492ccd82da40f485dfa0c), which run along the kitchen floor or ceiling. Note, that robot arm should be equipped with such grabbing device, that it could pickup plates and other dishes. When you have that setup you just simply set the zone for plate dropoff and connect robot with dishwasher. Regarding dishwasher - forget about classical consumer design we use today as it is not most optimal type to be used with robot arm. For bowls, plates, glasses, etc... the preferred design would be probably [conveyor belt washing machine](http://www.ph.all.biz/img/ph/catalog/17345.jpeg). As for cleaning spoons, mixing tools and other equipment mostly used by cooking robot, i'd go with something like [CNC magazine](http://2.bp.blogspot.com/-lXZBOsCK9Q8/U4BmazteJ9I/AAAAAAAAP58/AeBkoXRcUBs/s1600/CNC+Tool+Magazine.jpg) with high-pressure water nozzles type washing machine. [Answer] There are no dishes: the "pits" for eating are on the table, and self-cleaning. Maximum time and energy save provided with this solution. Forks, Spoons and Knives are placed in a smaller pit. * No need to spend energy moving the dishes. * No need to have a Sink which have flowing water (moving water requires energy, also we usually waste too much water by opening closing the tap too early or too late). * No need to search for dishes: save time. * This solution is more cheaper than classical kitchen room because of Eco-Incentives provided by countries (even if it has more technology inside). * The cooking pit also have self-cleaning. * Cooking pit is directly connected to organic waste exit: it is known that most people don't do waste differentiation. * There is much less space used in the kitchen, allowing for more living space, or allowing smaller kitchens. Insight: - The washing works by insetting the dishes below the table, they are moved to the center and washed by a machine identical to dishwashers. Cold water is drained directly into sewers (or into water recycling circuit), Warm water is drained into pipes below the floor to increase home's energy efficiency (heat is returned back to floor, where it flows up to the ceiling). Alternative There is a Flying drone that regularly check for "dish-like" items, it is trained with image recognition to take dishes and put them in a dishwasher. However it is know this is not a eco-friendly solution * Most robots cannot efficiently fill the dishwasher (which turns out to works almost empty). * You use much more energy just to keep operative the Flying drone. * Small accidents of drones putting to washing wrong items are known. (especially high-tech, not waterproff items that resemble in the shape a dish). [Answer] You've specified that the dishes will be washed in a dishwasher, which means that at that point they are in a known location (and a known configuration) which will allow for easy relocation. You don't specify whether the dishes used by the iKitchen will also need to be accessible to humans. If this isn't the case then you can just make the dishwasher big enough to hold all the dishes, and you'll never have to relocate them at all. Just pull them out when you need them. This doesn't require too much in the way of space, because you gain the space where you would have stored the dishes otherwise. If the iKitchen needs to allow for the possibility that humans might want to retrieve dishes themselves, then accessible storage is more important. In this case, you might want to make use of a conveyor belt system. It would resemble a sushi restaurant's system (because in such a luxury item, image is everything) but have the function of a postal distribution centre, with the ability to direct specific items off onto little sub-belts. Needless to say, this option has far more points of failure, though it is still preferable to large mechanical arms swinging around the kitchen. The real problem, however, is actually how to collect the dishes in the first place. While the iKitchen will know the location of items within its system, once it serves these items to a human being then all bets are off. The iKitchen will need to have a system which can traverse the various rooms of the house (without disturbing the resident humans), recognise dishes (specifically dishes which the human has finished using), and bring these back to the dishwasher. I assume this is what you mean when you say it will load the dishwasher itself. This is a massive challenge, and one that I can only see being accomplished by an iRobotButler -- or at the very least, an iDrone. However, if you go down this route then you may as well go the whole hog and have the iRobotButler put the dishes away after they've been washed. [Answer] Thank you to everyone who participated in this Q&A. I have taken many of your ideas, and included them in this answer. The features sections (below) cite your suggestions. Summary Use a [Moley](http://www.moley.com/) two-handed, ceiling mounted kitchen robot to handle the dishes and cooking implements. Use iKitchen dishes, cooking implements, and custom cabinets. Use an oversized silicone suction cup to gently pick up / put down the top items in stacks of plates and dishes. Use a fast commercial dishwasher and a set of racks. These dishwashers have a three-minute cycle time, a 180°F sanitizing rinse, and automatic drying. When the iKitchen has prepared the food, it puts it in a "butler's pantry"; humans take the food from the butler's pantry to the dining room. When the humans are done eating, they return the dirty dishes to a dishwasher rack in the butler's pantry. When the robot is not cooking, it tucks itself up out of the way. A human can cook in the kitchen, as long as they make sure that the robot's work areas are clear before the robot needs to start cooking. "Seasoning to taste" can be done via sliders on a touch-screen app. The whole system can be built and installed within the proposed budget. Total cost I come up with a hard cost of $ 50,000 - 60,000 (not including "the cost of ordinary walls, floors, windows, and doors"). Some of these prices are based on Seattle-area construction costs; others use on-line prices or a want-to-be manufacturer's hoped-for price estimate. After adding in taxes, project management costs, and other contractor markup, the iPantry and iKitchen might add 70,000 - 90,000 dollars to the cost of a house. I am sure people will come up with ways to increase or decrease these cost estimates. Effect on House Design Because most of the cooking in the iKitchen is done by a robot, the kitchen layout can be simplified. For example, there do not need to be windows over the sink, nor near the stove. This allows a linear, one-wall kitchen layout. The iKitchen does not need to be on an exterior wall, provided that the range hood is properly vented to the outdoors. This enables more options for the rest of the house design. Remaining issues I did not come up with a method for bringing in the groceries (possibly from an Amazon Prime delivery) to the iPantry. I did not address my wife's concern about how the iKitchen would wash and trim "tedious kale" and other awkward foods. I also did not address [Separatrix](https://worldbuilding.stackexchange.com/users/16295)' and [coteyr](https://worldbuilding.stackexchange.com/users/11158)'s concern about how the trash/recycling/compost would be taken out. Those issues might make good follow-up questions. Here are the major features: About $ 7,000: Dishwasher A small commercial dishwasher with: * drying cycle * enough room to wash platters, cookie sheets, and stockpots * high temperature (180°F final rinse) * each "rack" of dishes takes about three minutes, and a couple gallons of water. The system might need four racks, and room for a fifth: * one for the iKitchen's dirty dishes. * one in the dishwasher. * one in the butler's pantry, for people to put dirty dishes in. (This addresses [Dan Smith](https://worldbuilding.stackexchange.com/users/32002/)'s [concern](https://worldbuilding.stackexchange.com/q/68044#68055) about how the dirty dishes would be retrieved.) * one for the clean dishes that are being put away. * room for whichever rack needs to be moved next. About $ 15,000: Robotic arms designed for cooking As [suggested](https://worldbuilding.stackexchange.com/q/68044#68086) by [user2720406](https://worldbuilding.stackexchange.com/users/32266), the cooking (and dish handling) can be done by ceiling-mounted robot arm(s). In particular, [Miroslav](https://worldbuilding.stackexchange.com/users/32260) Saracevic [suggested](https://worldbuilding.stackexchange.com/q/68044#68065) Moley Robotics' Automated Kitchen system. It includes a pair of robotic arms and hands, mounted on an overhead crane. [Moley](http://www.moley.com/) has [demonstrated](https://www.youtube.com/watch?v=A5wWL4pNeis) a prototype system. As suggested by [Jasen](https://worldbuilding.stackexchange.com/users/16816), [John](https://worldbuilding.stackexchange.com/users/29409), and [Whinja](https://worldbuilding.stackexchange.com/users/11585), these hands are capable of manipulating the cooking tools, putting the dirty dishes in the dishwashing racks, handling the dishwashing racks, and putting away the clean dishes. They are effectively an iRobot that is restricted to the iKitchen, as suggested by [Snowlockk](https://worldbuilding.stackexchange.com/users/18882). A Moley [video](http://www.moley.com/video/moley_future_served.mp4) addresses one of [coteyr](https://worldbuilding.stackexchange.com/users/11158)'s concerns. The robotic hands are designed to stay out of the way when a human is using the kitchen. The iKitchen can actually watch the human cook, and emulate the human's motions in new recipes. The human would need to be tidy, so that the robot's cooking surfaces are available when it needs to cook. Unfortunately, the robotic hands are not able to "take out the trash", and it is not obvious how "seasoning to taste" would be done. [Chris H](https://worldbuilding.stackexchange.com/users/6348) and [coteyr](https://worldbuilding.stackexchange.com/users/11158) asked about the user interface for "seasoning to taste". The Moley video shows a huge touch panel monitor that is used to choose recipes. Perhaps the app could have a "pull-out" "Seasoning" pane. The pane could have icons and sliders for the levels of various seasonings (sweetness, salt, pepper, capsaicin hotness, ginger, and/or other seasonings relevant to the recipe). These settings could default to what was served most recently for a similar recipe. There could even be a toolbar in the pane for choosing different users' settings. I wonder if the arms can be designed so that one arm can detach the other, put it through a dishwashing cycle, and reattach the second arm. About $ 2,000: Tools A set of bowls, plates, pots, pans, cookie sheets, flatware, knives, ladles, spatulas, silicone lids, and serving implements. For compactness, nestability, durability, and microwave-safety, the bowls and plates could be [Corelleware](http://www.corelle.com/). The pots and pans could be induction-range compatible. The silicone lids would have center grips, and would be used as suction cups. As [Erin](https://worldbuilding.stackexchange.com/users/23058) Thursby [recommends](https://worldbuilding.stackexchange.com/q/68044#68109), "All dishes must be iKitchen dishes and cookware." There are several reasons for this: * The iKitchen "will be less likely to malfunction if dishes are a specific size and programmed to go into a specific place, sized for being put away there." * Induction cooktops can only be used with certain kinds of pots and pans. * The exact materials and sizes of the pots and pans affect the cooking times. * Avoiding teflon-like "non-stick" cookware prevents accidentally scratching off the "non-stick" surface, and accidentally burning up the teflon. * The iKitchen can more easily recognize which proprietary dishes and cookware are microwave-safe and/or oven-safe. * The iKitchen might be able to notice if a proprietary item has broken, and order a replacement. About $ 3,000: Refrigerator A cabinet-depth refrigerator with ice-maker. (Part of the iPantry). About $ 4,000: Cooking appliances Hot things, and the ventilation to keep the kitchen cool and dry: * An induction-range. These are easily cleaned, and have less risk of fire than natural gas ranges. * A large oven (suitable for cooking Thanksgiving turkeys), a small oven (suitable for cooking cakes or pies, or for keeping them warm), and broiler functionality. * A microwave oven. * A quiet range hood. * An interlocked air inlet that opens when the range hood or house exhaust fan is on. About $ 2,000: Other appliances Other kitchen appliances: A blender, a mixer, a toaster, a rice-cooker, a waffle-maker, fire extinguisher, et cetera, as desired. About $ 9,000: Cabinets A set of custom cabinets, including the cabinets in the iPantry. As [Erin](https://worldbuilding.stackexchange.com/users/23058) Thursby [recommends](https://worldbuilding.stackexchange.com/q/68044#68109), "All cabinets must be iCabinets." The iCabinets can have a place for every thing, and vice versa. There might need to be some empty locations for future purchases. * Ladles, spatulas, and serving implements could be hung from hooks in pull-out drawers. If it is too hard for the robotic hands to removed flatware from stacks, perhaps the flatware could also be hung. * Spices could be stored in pull-out drawers. (Part of the iPantry). * Each kind of bowl or plate would have its own drawer. These items would be stacked. Here is a method for stacking dishes. The process would be reversed to remove an item from the stack. ([cybernard](https://worldbuilding.stackexchange.com/users/20023) [suggested](https://worldbuilding.stackexchange.com/q/68044#68147) using suction to place the dishes. It addresses [Loren Pechtel](https://worldbuilding.stackexchange.com/users/264)'s [concern](https://worldbuilding.stackexchange.com/q/68044#68086) about getting exactly one item from the top of a stack.) 1. The robotic hand(s) would open the drawer. 2. One robotic hand would grasp the item to be put away, and place it about an inch above its stack. 3. The second robotic hand would grasp an oversized suction cup, and apply the suction cup to the item. My wife has a set of silicone lids (with center grips) that can be used as oversized suction cups. The lids are dishwasher-safe. 4. The first robotic hand would get out of the way. 5. The second robotic hand would gently place the item on the stack. 6. The first robotic hand would then peel off the suction cup. About $ 1,000 - 5,000: Countertops Countertops. Post-formed laminate would suffice, but solid-surface or quartz could be upgrades. About $ 3,000: Butler's pantry The butler's pantry. About $ 7,000: Wiring and plumbing Pro-rated share of house wiring and plumbing costs. Includes sinks, fixtures, smoke alarm, and lights. [Answer] # iKitchen? Why not iDine. An all-in-one. It works on the premise of a rotary system. Let's assume an outer rotatable platform upon a round table. The axis contains a CPU capable of the following functions; catering, arrangement, cleaning (plates, cutlery, etc), dispensing garbage. A small 'treadmill', that can realign on the fly, acts as a taxi between the CPU and outer platform. Before dining, simply input data such as; meals, seat numbers, etc. The CPU preps and outputs the dishes via the taxi. The outer platform and taxi work in unison - this ensures the correct dishes land on their correlating seat numbers. Once everyone's done eating, the taxi deals with returning dishes to the CPU. The system essentially enables dishwasher mode - given 15m, it's good to go again! Patent pending. [Answer] Certainly 3D printers will be advanced enough to handle plate. After use the plates are heated and/or crush back into a liquid to be re-used by the 3D printer. The melting phase will happen at say 1000F so the heat will sanitize it. Maybe a quick high pressure wash to get the big pieces off. If you wanted to put it any dishes away, use a suction cup with a vacuum tube down the center, and turn the vacuum off when you want to set it down. [Answer] Seems to me we need to rethink the kitchen entirely. Where do dishes go when they are put "away?" We have cabinets and cupboards that we keep dishes in, so we always know where to find them. But who needs to find them? The iKitchen delivers them to you when you need them, with your food already cooked and upon them. So what do you care if they are in a cupboard or simply in a rack somewhere under the counter (which no longer needs drawers and doors)? In fact, who even needs to go into the kitchen? Why make it a walk-in room? The kitchen is the new water heater. Give it a door for maintenance but otherwise leave it in a corner of the house and ignore it until it breaks. The only part of the iKitchen that merits concern is the attached dining room table, which extends out of the iKitchen and into the dining room, featuring a conveyor belt that supplies and retracts food and dishes directly from the iKitchen to the dining room table! The sleek design of the belt even sits flush with the tabletop so your guests would never guess that it was anything but a fancy table runner until, to their surprise, out comes the delicious meal! For an extra charge, you can even have the technicians install more tables and counters in various rooms of the house. Using discreet speakers in each of these rooms and speech recognition technology, anyone in the house can order a meal (or snack) from the kitchen from any room in the house with ease, and have it delivered to the room in which they ordered it! With its ability to distinguish voices from one another, you can even set parental controls to ensure that the kids don't eat too much junk food! Restocking is also automatic. The iKitchen keeps constant inventory and orders more of a food when it runs low. Self-driving cars deliver the food to your house and place it into the iKitchen's intake. The iKitchen intelligently sorts through the package and stores cold foods in the refrigerator or freezer. It also checks "best by" dates and alerts the owner when such a date is approaching, then offers a list of suggested meals using those ingredients. Should the user ignore these alerts and the food should expire, the iKitchen discards it automatically as well with its interface to the iGarbage (sold separately). Users can also configure the iKitchen to keep and use certain products for a specified number of days beyond their expiration date, with the quick signing of an e-waiver that resolves iKitchen of any responsibility. Order yours today! [Answer] 1. No carts, belts, or anything else to do. Eat and leave. Entire kitchen and eating room is dishwasher interior. On meal ending (and guests leaving!) room tilts up and forward at 45 degrees. Additional movements of the room ensue, to facilitate cleaning. All surfaces are lashed with hot water and detergent, as the interior of a dishwasher. All utensils are unbreakable and tumble thru the room via gravity and jets of hot water to an egress point in the corner of the room, which is now the bottom of the room. Utensils are caught on screens, tumbled, cleaned, dried, sorted by size / weight / electrical impedance and stored out of sight. Unclassifiable solid items (e.g. steak bone, uncle's dentures) will go to trash hopper for later reclamation or disposal. Sterile, clean room is drained, dried and reset to normal alignment. Bathroom should have the same set up. Also operating room, if you have one. [Answer] Depending on the technological progress you allow for the next decades, maybe you should think much further than "putting away dishes". The answers by SRM and ArgumentBargument are pretty good in my opinion. But if you allow for even more technological progress: how about using holographic dishes - holographic as in "Star Trek Holodeck"? The dishes are just force fields and visual projections, and can be created and destroyed at will. I assume that holographic food is not quite possible; so when you disable the force fields of a dish the remaining food will just fall down, preferably into a trash can. ]
[Question] [ So, in my story, there are six main categories of magical abilities, and everyone's able to have 5 abilities at a time. Each category of power has its own limitations on, and rules for, their use, and one category, called "Tribute", allows you to temporarily disable a certain number of your other powers to manifest something into the world: either an object, a totem that alters physics in the area around it, or a loyal animal companion. These will persist until they are either dismissed by their creator or destroyed, and either way the tribute power and the powers tributed to make the creation will remain unusable for an hour after the creation's destruction or dismissal. Now I like this concept, but a problem with it stuck out at me almost immediately: Nobody would want to have them. No warrior with any significant backing or funding would disable any of their own powers in exchange for a cool magic sword if they could have their squire conjure it for them, or pay a civilian to borrow theirs, and still have all of their own powers intact. And the same goes for familiars: just have somebody who'll be far away from danger summon their own and then instruct it to follow someone else's orders. Boom, same benefit, but without anyone who'll actually get into a fight paying the price to their power. While obviously for people and organizations with limited resources or manpower this wouldn't be an option, it still seems to me that it'd be pretty lame to have an entire category of cool powers that would never see personal use in "high level play", as it were, because whenever you have the option it's always better for someone else to use them for you. So naturally the obvious course of action was to contrive mechanisms to make this sort of abuse impossible. For items, I figured that since all tribute powers are all manifestations of the user's spirit animal / familiar, they have a mind of their own and, upon recognizing an attempt by somebody other than their master to use them, they instantly teleport back to their master's side. The world-altering totems aren't a problem because they're stationary and are generally intended to be used by more than just their creator. But for summoned beasts? I can't think of anything to prevent the "I want you to do what this guy says" exploit that wouldn't involve making them amazingly unhelpful to people working with a group, or creepily sociopathic towards anyone who isn't their master (the main character has one of these and I want him to be an endearing and likable animal companion for him). Why would using somebody else's summoned familiar, ordered to obey you, not work, or at least not work well enough to keep people from making the sacrifice to their powerset to use their own? [Answer] The summoned creature only communicates with its owner telepathically meaning you can't just order it to obey someone else as they have no means to communicate to it. The summoned creature only has a range of of a kilometer meaning its owner has to remain close by otherwise the creature will dissipate. The summoned creature is empathically linked to the owner meaning they feel what the creature feels. Just a few possible ideas. [Answer] What if not everyone's creations are equal? Let's look at your problem: > > No warrior with any significant backing or funding would disable any of their own powers in exchange for a cool magic sword if they could have their squire conjure it for them, or pay a civilian to borrow theirs, and still have all of their own powers intact. > > > Put this in D&D terms: * Your level-18 great warrior can make himself a +5 vorpal sword. * His squire can make him a +2 sword of sharpness. * A civilian can make him a +0/+1 sword. Many warriors in that situation would sacrifice one of their abilities to get the +5 vorpal sword. The same idea works for familiars, companions, totems, etc. An ancient gold dragon is a lot more useful to have around than a young squirrel.1 --- But couldn't there be powerful people who create items to lend them out? Sure, a retired level-16 warrior can lend anyone a +4 vorpal sword. But how many of those are there? Not many, so the few that exist are in high demand. It takes a lot of money, or a major quest, or a year on a waiting list, to get him to do it for you. Not to mention that when you're in real danger, facing an unexpected attack by an archlich, that retired warrior isn't around. You make your own sword, or you don't have one. --- But what if you're going on a quest to save the world, and have a whole kingdom backing you? Well, yeah, in that case, they'll pull together whatever resources they have to get you the great artifacts you need. Unless they need those artifacts to defend the city while you're off on your commando mission, in which case they may not be able to afford to give you anything too exciting. --- 1. OK, Doreen Green might disagree, but then her power is liking squirrels in the first place, so I'm not sure what happens if she gives up that power to get a squirrel… [Answer] The summoned creature is not a slave. It is a sidekick. You can allow someone else to ride your horse. You can have your slave work someone else's farm. But if your friend decides to help out someone, he does it as a favor to you; he chooses to do so. If you abuse your friendship it might not last. He will not do what you ask him to do and he might get less enthusiastic about you too because he feels you are taking advantage of him. The familiars are autonomous entities. They are not bound demons compelled by geas. Your familiar is with you because it thinks you are great. The familiar chooses you and vice versa. A bond based on friendship must be maintained. Don't screw it up. [Answer] Why should your squire summon their familiar in the first place? If their familiar is sufficiently amazing, perhaps they are the leader, and the knight is just there for muscle. It sounds to me like the issue is that the power of this "Tribute" is not sufficiently tied to the power that is being given up. Match the power of the tribute to the power being given up, and you get rid of all the problems. You wouldn't have a squire summon a familiar because the squire's familiar is weak and you have to consider that the squire might have been of more use with all their magic. Likewise, if an awesome warrior's familiar or totem is sufficiently awesome, it may be worth the trade. Also, always remember the opportunity cost is paid by someone. Someone has to lose a magic ability for a while. That person will need to either make sure they sell their magic for what it's worth, or get enslaved by underselling it. Perhaps the issue is that your squire's union isn't doing their job at the negotiating table. Negotiate higher wages! Alternatively, if everyone's totems/familiars are amazing, build a world around that! Have wars where the side with the highest population wins because they can summon a bunch of familiars and overwhelm the other side, even though they may not have much training. There were battles in Korea between the US and Chinese soldiers which were basically dominated by the Chinese ability to put a large number of human bodies with guns on one side of the battlefield. Large numbers are a real factor in real battles. On a related note, I played a MMORPG a while back where one class was truly defined by their pets. It created an interesting dynamic where players of this class would be brought into groups because their pet was awesome, and then they basically put themselves on "follow" and hung around in the back not paying attention to the game. Their pet did all the damage. So you can indeed create systems where the familiar/pet/etc. pattern is not properly balanced. Just don't do that =) [Answer] ## Why don't warriors pay someone to hold a shield in front of them? After all, No warrior with any significant backing or funding would disable any of their own hands in exchange for a cool magic shield if they could have their squire use it for them ... and still have all of their own hands free. Of course, this never actually happens, because a skilled warrior doesn't use a shield as a tool, but as an extension of themselves. That shield becomes part of their arm, and as a result, the feedback loop between the warrior and their shield is as small as possible. The warrior thinks "I need this shield here", and the shield goes there. Once you introduce another step (our trusty shield-wielding squire), the feedback loop gets bigger. No matter how good our squire is at catching errant arrows, the warrior will always put their shield where they want it faster than the squire can. Likewise, I assume great warriors view their tributes as an extension of themselves as well. I assume they know and understand their tributes better than anything else too. Therefore, when it comes time to rely on a tribute or familiar why would they possibly rely on someone else's? "I want you to do what this guy says" is an *enormous* feedback loop. In the same way a squire simply can't defend the warrior better than they can defend themselves (and if they can, then the two need to switch jobs), a squire's familiar will never be able to protect the warrior as well as the warrior's can; it's an extension of the wrong person. Sure, the warrior could be shouting "go there", "eat that guy", "come back" the whole fight, but that's far less reliable than a familiar with whom you're bonded. Plus, if there's any level of empathetic bonding (the familiar can feel what you feel), you've made the feedback loop even bigger again. A familiar which can sense that you realized your back's exposed is far more valuable than one which just has to guess. On top of that, warriors become familiar with the tools they've been using, and can use them better than others. Have you ever played a game where you trade in your weapon for one that's objectively better, but drastically different? Did it take some getting used to? Sure, after a while you were better than before, but there's a learning curve to these things. I'm betting most warriors don't want to fight with a weapon they're still working out. Using someone else's tribute puts you on that learning curve again. You simply can't be in the middle of a fight and be thinking "ok, if I attack this guy over here, is my squire's familiar going to attack him with me, or will it make sure noone sneaks up behind me?" You just can't; you'll die. You have to know these things before the fight begins. Just as important as raw fighting ability is tactics and foresight, and no great warrior would sacrifice these. [Answer] While there are already a lot of great answers I agree with, I'd like to tackle this problem from a bit different angle. ## Summoning at a time of need gives you flexibility Suppose you are going on a prolonged adventure, and you aren't sure what to expect. Which familiars would you take? You can't just grab a pair of every kind of beast, because, you know, logistics. So you take a bull, a squirrel and a giant eagle, hoping those would cover all your bases. First you come to a mountain stream, with a rope-bridge straining across. It starts cracking as soon as the bull tries to step on it, so you have to send him back. Then you arrive to a cave system, with narrow tunnels leading to the other side. The giant eagle can't fit in, and doesn't know where the other exit is. She flies around while you delve inside, then gives up and returns to her master. With a magic squirrel as your only companion, you find yourself at an edge of some swamp. The air smells weird, but it's not a problem for you. You realise all too late that squirrel's small body isn't as resistant to poisoning. And now you are left alone, all of your borrowed familiars gone. Compare that to summoning whatever beast you need. Sure, you give up some of you power, but you get the exact tool you need right now. Exploring dungeons? Summon a trusty fiery Balrog. Need to get to that volcano? Okay, you lose your powers of water-breathing, but get a giant eagle to carry you all the way. Invited to a king's castle as a guest of honour? Suddenly, a venomous snake appears in king's bedroom. If you can choose what you summon, then exchanging a fixed power for a familiar of choice is often a superior option. [Answer] There is also the issue of trust. How can you be sure the invoker won't dispel the summon right when you need it the most. Or have it backstab you in that big drama moment. A long time friend will have that trust to not betray you like that, but a random stranger you payed a few gold coins for the summon won't. There can be a few rental businesses that will rent out summons. However that market is underregulated so a few years ago a lot more of untrustworthy summon-rental shops cropped up that will typically not honor the rental agreement and damaged the reputation of the rental practice as a whole. After the high cost of summons disappearing like that at critical times the adventurers are very reluctant to entrust their lives to rented summons at all. [Answer] This is a classic problem. Generally solved by the fact that the summons is either: a) Completely loyal to the summoner or b) Completely disloyal to the summoner Summoned Familiars: In case A, they are actively interested in following commands from their summoner. Summoner, possibly dead, tell them to let Person X inherit their familiar, etc? Then the summons is going to do everything in it's power to get back by it's master's side or protect it's memory/possessions. In case B, you have classic demon summons, they're just out to kill you anyway, so while it doesn't really matter who they're following around... somebody more well-versed in handling them might be better. This would be the case of "You're not learned enough to be controlling my familiar". Ordering case B to treat someone else as their master is a recipe for suicide. Demon: "Should I prevent anything that could drop your future battle prowess?" New Master: "Yeah. I don't want to be less powerful. That's why I got you in the first place." Demon: "Time to go kill my previous master. Wouldn't want him taking me back from you..." Case A is generally going to require an emotional summons. Which makes items tricky. So moving onto those: Summoned items are essentially like a blacksmith's master product. There can be only 1. Okay maybe that's not quite true. But the idea is your Tribute skill takes a minimum of 2 slots on a person. Have the magnitude of each person's slots be something innate/trainable (or both). Having a peasant make you a sword might be some trash iron sword. A person that devotes their life might make a masterpiece. A +1 sword if you will. On top of this, a peasant might only be able to devote 1 slot to a Tribute. While a trained/talented person could devote more. If they devote four slots to the Tribute instead of 1 then maybe the more excellent person might make a +4 sword. But the same person could have easily become a force of reckoning on their own. They would already be a warrior, but acting as a squire for someone else. There's no personal benefit to this. Yes you could make the Voltron Warrior, with +4 pieces from multiple warriors. But what's the incentive? You'd need a significant enough reason to stop each warrior from wielding their own +4 and an incentive for them to sacrifice their other slotted powers in the first place. In other words: Shit probably has to hit the fan. ALSO, if summoned items don't survive after a person's death then the person who summoned them is an additional weak point on the warrior in question. If every link in their chain mail was forged via Tribute then not only are they protecting the town but they have to. There's also the potential for their sword to randomly disappear in battle if their master blacksmith suddenly dies or is assassinated. TL;DR Summons conflict of interest, greed of Tribute-rs, "unknown factor" of vulnerability for second-hand users, skill at manipulating someone else's creation. [Answer] The Summon is just a projection, and has no inherent powers of its own. The real power is still utilised by the Summoner - that is where the "spent" abilities are invested. With a summoned creature, this is not much of an issue: When Summoner and Summon are in the same area, the summon can be directed around in much the same way as managing troops in an RTS, or given basic commands to follow autonomously, such as "go there", "fetch that" or "attack that person", but not more complicated ones like "attack the people wearing red shirts, unless their cuffs have 3 or more stripes or they are holding a 3-pointed dagger". If the Summon and Summoner are in different locations, then this can cause disorientation - to issue accurate commands, the Summoner needs to "borrow" the Summon's senses, but this splits their concentration between the Summon and their body. One option is to sequester yourself away somewhere safe and control the summon directly - but, at this point, you are more of a shape-shifted party member instead of a borrowed summon. As for artifacts such as swords/shields/bows/spears/magic staves - these (typically) only work so long as the Summoner is aware that they are being used - if the Summoner doesn't know that you are firing their Bow of Shaded Sky, then the "Multiplication of Arrows" effect won't take place, and you only fire a single arrow. Also, some summoned items will only work for the summoner - especially ones that are "telepathically controlled". Again, this can be worked around by making your artifact feed-back to the Summoner - if pulling the trigger on the Lightning-Boom-Stick sends a sends a signal back to the Summoner in the moment it takes to 'charge' before firing, then it will work so long as they are alive and conscious. [Answer] > > In psychology and ethology, imprinting is any kind of phase-sensitive learning (learning occurring at a particular age or a particular life stage) that is rapid and apparently independent of the consequences of behaviour. It was first used to describe situations in which an animal or person learns the characteristics of some stimulus, which is therefore said to be "imprinted" onto the subject. Imprinting is hypothesized to have a critical period. > > > When you summon a familiar, you have to bind it to you via imprinting. You may tell them to follow and obey domeone else, but the familiar will always make its way back to you. Depending on how intelligent the familiar is, they may even rationalize the reason they do so. [Answer] The summon is a power of a person manifest. It makes sense that the summon would be feeding off that person's power. You can have a good amount of limits based on this. Perhaps the summon requires to "recharge" at his owner once in a while, putting a time limit on a summon away from it's owner. The energy requirement to keep the summon alive isnt that high, but the owners energy loses power with distance. If it moves too far the summon will not be sustainable by the owner and dissipate. The owner might need to keep a small amount of concentration to keep powering the summon or it'll dissipate shortly after. That's easy when the summon is around but if you cant see it or fall asleep it can dissipate without the new "owner" knowing when or why. Then theres the usual reasons you can imagine like summons having a mind of their own and that causing things like not cooperating with others, unwilling to risk their wellbeing when their owner isnt directly threatened or similar reasoning. Perhaps the summon simply isnt capable of understanding the other person and will just wander off. Or the summoned creatures strength is linked to the summoners capability. Another intriquing question: why are there still warriors? Couldnt you just summon 5 creatures, send them in (with other people's summons for example) and if it fails try again in an hour while you keep your distance? Or you summon two or three and use the remaining powers to support your summons? [Answer] Why not just have people rent their familiars/magic equipment out? That sounds pretty different and interesting. You could have an entire industry built around lending people aid like that. You could have rituals and customs, and sworn oaths regulating how people lend their familiar to others. You could haven noble families who try to keep their familiars completely within their own family, and other nobles who lease them out far and wide. People might have to trade favors, or marriage, or swear an oath of loyalty to a family to get access to their familiar. You could do a lot of interesting things with the particulars as well. When a familiar die, maybe that strikes back at the summoner and weakens them significantly. Accidentally killing someone because the familiar you lent them died could leave you with enemies. Maybe there is a way to inherit familiars/relics, so long as the new owner pays the price. Then a family could keep one familiar/relics in service as long as someone in it is willing to pay the price. Who gets that honor? How easy and common is that? You could have romantic stuff, like a knight going into battle with the loyal hound his wife summoned, who protects him in battle. It feels like you have an interesting concept, and you are asking about ways to make it more generic and plain and boring. [Answer] Simply, cost I assume that magic is a skill or rare gift. So to summon a mighty displacer beast you have to be a damn good wizard and disable all your other skills. So, there won't be many wizards that can do that and they'll charge a lot of money for their services. Also it'd likely be a lease - a wizard can rent you out a planar demon for a day, after a day he will unsummon it unless you keep paying him. And it's gonna be crazy expensive. It's likely that the wizard would be vulnerable while doing this so they will take a lot of precautions as well as it driving up the cost. It might also require a lot of mental energy to maintain. Familiar specific ideas Increase the danger to the caster, drives up the cost / infeasability. If you make it so the familiar must remain near to the caster, the wizard must come with you and also has no defensive capability during that time, since half his magic is gone. Risky and expensive. If you make it so the familiar can only 'hear' (or receive commands in the case of pointing etc.) the caster (so the caster doesn't have to come into doom-dungeon with you), then it will probably do something stupid. You'll give it a command to protect a person, and then it will start killing everything that comes close, friend or foe. It'll essentially be useless except as maybe a pack mule. That may also be influenced by the intelligence of the creature. In D&D if a familiar dies then it cripples the caster. You could apply the same to familiars and even objects, such that if the item is damaged or destroyed it hurts the caster. They likely won't want to summon things for you if there's a risk of damage. [Answer] One way to achieve this would be to make it very risky for the lender. If the item/familiar is to far away, it will begin to fade over time, as well as the invested power. If it is destroyed or banished and the caster is not close to it, only a fraction of the power invested will return. There could be also a way to absorb a part of the power, and by doing so stealing it from the Caster. [Answer] There are a number of ways you could approach this. ## Investment of Power Firstly, you need to ask yourself - what happens to all of the other 'powers' if they're invested into the object or creature? Do they manifest as more than simply a powerful item or creature? One option would be to utilise these powers to not only make the object more powerful, but also to limit its power. Take a sword, for instance. All of the powers are required to make the sword, irrespective. So, the user knows that the sword is going to take their powers, but couldn't they be channelled into the sword in different ways. For instance, one of the powers could be utilised to make the sword unbreakable, one to give it a constant electrical charge, another to make it razor sharp, and so on. Or an animal; all powers make the animal, but you could give the creature wings, speech, intelligence, telepathy. Power invested into such a creature or object should not be diminished - it should be externalised, creating a super-powered object reflecting the creator's own abilities. ## Psychic Linkage Telepathy brings me onto the next idea. Should you disregard the first idea, why not also give a creature or object a continuous psychic link with its creator. Such objects could be used for espionage - any other being that touches the object or creature would have their thoughts opened up to the originator. ## Bound Creations The most simple way around this is to make the power bound to the originator. If someone else attempts to use the item or creature it reacts unpredictably, to the detriment of the user. This is similar to what @Renan has suggested, however, as the powers belong to the originator in the first place, then the created object or creature are bound to them naturally. ## Taking it Further... Finally, you may want to consider that, if the powers used to create the object or creature are bound, or there is a psychic link, then perhaps it can be controlled remotely, or at least its whereabouts known. [Answer] An addendum to the multitude of other good answers here is a relatively straight forward solution, which can be used in addition to any number of them. The Tribute creations disappear when the summoner is unconscious, and can only be summoned to the location of the summoner. When your squire goes to sleep at night, the sword he created vanishes. When the mighty (but elderly) retired hero takes his afternoon nap, the ancient gold dragon familiar he summoned vanishes. Neither one can be re-gifted unless the recipient is near enough to the summoner for the hand off to happen. That's not a problem if the squire is traveling with his knight, but it presents a problem if he is left at home, or if he dies in a battle. In a pinch, you make sure your squires are safe, and kept awake. But if one of them falls asleep due to sheer exhaustion while you're facing some ancient horror from beyond time & space, you've got problems, so it's probably better for you to use the Tribute ability to create your own gear for the really important stuff. World-altering, permanent objects might require the investment of more than one person, and/or more than one power, making them the work of great masters at the end of their careers or lives, or entire teams of lesser journeymen, dedicated to maintaining that single object. [Answer] Time Constraints Tribute is great, but anything that it creates lives on borrowed time, commensurate to the power of the summoner: * untrained/squire: a few seconds to a minute, * journeyman: a minute to 10 minutes, * master: 10 minutes to an hour, * best of best: there are legends that some invididuals could maintain their conjuration for half a day; but everybody knows it's exaggerated. --- And thus Confidence In such a situation, wow can a mighty warrior borrow a conjured up sword with confidence? They cannot: * if the master is close, then they are at risk; should they get embroiled in trouble, they may accidentally dismiss the sword. * if the master is far, then by the time the warrior get their hands on the sword, it's unclear how long they've got before it winks out. Few warriors will trust their lives to a conjured sword which can wink out at any time; or at least, few living warriors are there to tell the tale of the time it happened to them, for it's generally fatal. [Answer] All your mentioned problems come from one thing: the limitation is on the summoner, not on the user. So put the limitation on the user. Sure you can make the limitation on the summoner as well, it would be weird to summon a magical item or beast from another realm without any repercussions. But also add the limitations on the user. If you are a magician with a borrowed sword, you still need your hands to cast spells. If you lend a magical beast, you still need to communicate your plans, whether verbally or through psychic link. If you are Ash Ketchum, you still need to be strong enough to control your Charizard. [Answer] ## "I know what you're using it for" Here's a small idea: the creator of the item / familiar knows what the item is being used for and how once the summon is dismissed? Imagine a mission of secrecy, or perhaps you simply you don't want people to know what or who you're slashing with that awesome summoned "sword of power"... In this case getting it from someone else is a major risk. Also, this would allow for some... interesting spy games. If someone could replace your sword with their own, for example? [Answer] Mental language: The familiar and the person have an very specific own mental landscape and context in which they interpret the world and communicate. The mental landscape of other persons just does not make sense to the familiar in a way that it can be interpreted. For simple things that could be ok, since both are maybe intelligent but in some sense it would be like speaking a foreign language constantly. ]
[Question] [ Based on a set of questions by [Pavel Janicek](https://worldbuilding.stackexchange.com/users/2071/pavel-janicek) about how to [address](https://worldbuilding.stackexchange.com/questions/32778/magical-internet-unique-addressing-system) and then [monetize](https://worldbuilding.stackexchange.com/questions/126728/how-to-monetize-magical-mirrors-in-todays-world) magic mirrors in today's modern world. The short version of these magic mirrors is that any one magic mirror can make a 2-way connection to any other magic mirror by the user asking their mirror to connect to another mirror by its unique name. Many of the answers to the monetization question suggest using mirrors to replace wires/fiber-optic cables/radio signals in current communication technology. The magic mirrors as described appear to: * Not use any power (no apparent power source involved, no apparent degradation from use) * Not have a limit on range (tested at 1500 km apart) * Transmit both vision (which we've all assumed means light, the full EM spectrum) and sound in high or perfect fidelity * Not require an infrastructure like wires or cell towers to carry a signal between mirrors * Understand natural language in at least 5 languages and presumably any language spoken by a human * Require a unique name, which can be any unintelligible combination of syllables, leaving an absurdly wide address space. * Understand and correctly interpret drunkenly slurred as well as computer-generated speech. (They may possibly interpret unspoken intent in the speaker's mind, further testing is required.) Magic mirrors can be created by an intelligent lay person (possibly on their first attempt; this was unclear) with $50 of materials and equipment in two hours' time. Those costs and requirements leave a huge potential for manufacturing optimization. The first modern maker of these mirrors, Pavel J., discovered some ancient documents in Baba Yaga's house detailing how to make them. He has created a small number of mirrors and done some basic tests of their abilities. As with any other new technology, there are often limitations and/or drawbacks which are not apparent when the technology is first discovered but which become apparent as the technology becomes widespread. For example, radio signals have a practical limit to how many overlapping signals can exist simultaneously before they start interfering with each other. It wasn't an issue 100 years ago, but it sure is today. What subtle limitations can be applied to how these mirrors function so that they are still quite useful, but not so overpowered that they turn civilization on its head? Good answers will have one or more limitation which * would not be immediately obvious to a lay person testing a handful of hand-made magic mirrors. * would not curtail the mirrors' abilities so much that they become useless or worthless if patented and mass produced. * will keep magic mirrors from directly causing modern society as we know it to cease to exist. * is not easily overcome or bypassed (eg the mirrors output cancer-inducing radiation; easily overcome by adding radiation shielding). * can't be misused by a mad scientist to easily destroy the world (eg duplicating photons in a loop to instantly create massive amounts of energy from nothing). * (ideally) resolves magic mirrors initially appearing to break the [1st Law of Thermodynamics](https://www.wikiwand.com/en/Laws_of_thermodynamics). (Note: perfect efficiency is ok, just no energy coming from nothing) * cannot itself result in destruction of the world as we know it. Answers will be judged on subtlety, simplicity, and robustness: * Subtlety - is the drawback difficult to notice in initial tests? Would it have no appreciable effect on ancient usage? * Simplicity - is the drawback fairly simple to explain and understand? * Robustness - does the drawback just introduce new plot holes or break physics in new (if interesting) ways? [Answer] Magic Mirrors require a focus -- they need to be directly in front of a living being in order to maintain their connection. Some say this is because they are draining part of the soul of the person (or, in some cases, animal) they are centered on, others say that it's like a computer timing out if nobody moves the mouse for a while. Functionally, this means you can watch somebody while they sleep, but you cannot connect to a mirror in outer space intending to pull unfiltered sunlight. Yes, you can move sunlight from a desert to a dark area, but only if you have someone standing around in the desert to be your mirror focus. And while they may get paid to be the focus for a few dozen mirrors at once, it's a hot, boring job, and that one time they needed to step away to go to the restroom, they got fired... This was especially frustrating for initial testing inside computer parts -- the engineer sets everything up, it's running perfectly fine, and then he walks away and it shuts down. A machine correctly connects the LEDs to the mirror, and it won't boot up until the tester comes over and stands in front of it. [Answer] One of the ingredients of the magic mirror is: - Half pint of blood of the maker. Baba Yaga is a witch (as far as I remember), so it may sound logic she included some creepy ingredient in such a wonderful invention. So the fabrication of the magic mirrors is limited by the amount of blood able to be retrieved from the makers in a month. [Answer] For resolving the issue with thermodynamics, the magic mirror shouldn't be creating new photons, or changing their arrangement at all. The mirror simply receives photons here and outputs the same exact photons there. It's teleportation with no energy exchange at all, except for the photons themselves which leave just as they entered. (It's magic, after all). Since their only function (from what I see above) is that they connect to another mirror by means of a unique name, I don't see any need for a limit on known languages. Whoever makes the mirror can specify a key-phrase and a name. When you want to connect to some other mirror, you say the key-phrase for this mirror verbatim, and then you say the name of the target mirror. If the magic were a little more sciencey, (and I'm "bending" the rules here hehe), then a limitation could include that the means by which the magic mirrors transmit this light is by bending the causality-axis of the observable universe around a [pick your number > 5]th dimensional axes, so that it contacts itself immediately at the point of the two communicating mirrors. The issue here is negligible at first, but if you use very big mirrors, or thousands of them at once, then small gravitational and causal distortions begin to appear in high-mirror-traffic areas, affecting the speed of light in those locations. Now, bear in mind, mirror-traffic occurs along a string, if you will, which doesn't move straight in the 3rd dimension, but may affect the speed of causality in some mathematically predictable location relative to the mirror. Furthermore, the distortions don't necessarily have to happen at the same time as when all the mirrors are in use, and the distance in space/time between the heavy mirror-use and the distortion may vary based on the physical locations of the mirrors in question. Since matter can't be passed through the mirror, but only light (and light-like stuff), magnetic forces may variably traverse the mirrors as well. This can be explained by means of a sort of filtering substance which is built into the mirror at design-time. The substance doesn't have to be a magical element, but could be a common element arranged in a very specific pattern so that it stops normal matter but allows waves to pass through it (like the way that the holes on the front of your microwave are just the right size to stop microwaves). The energy required to perform this could actually be stored in the substances comprising the mirror, and could be such that it is only released over a very very long period of time. We are so used to getting tiny bits of energy out of gasoline that we tend to forget the unimaginable potential stored in every single atom around us. Suppose you vibrate one of those atoms in just the right way, by saying the magic words to it perhaps.... and the magic mirror all comes together. So, what this looks like in practice is (in a very minor case), a bunch of people are using mirrors together, and then one of them is 10 minutes late to a meeting, another one feels like everything is very heavy (and everything is indeed a few pounds heavier) for a short time, and maybe another one loses his keys and finds them in a strange place. These kinds of small mishaps tend to happen inexplicably at first, granting the illusion that heavy use of these mirrors is bad luck in a sort of small way. Much later on, scientists measuring gravity and trying to understand the universe can begin to develop formulae around the specific behavior of the mirrors. So then the recipe for the mirror has to include at least two parts in addition to the regular mirror stuff: a magical pattern impressed on some substance, for stopping normal matter but passing waves through it; and a substance which is picked apart by the forces of the universe for the duration of the mirror's life (maybe a few hundred thousand years if the mirror isn't broken). I hope this helps! [Answer] Magic mirrors link to their maker’s life force, effectively stealing usable calories from the person that produced them in order to pay whatever energy cost they incur. When a mirror is in use a person must eat additional food to compensate, and if there are too many mirrors they’ll starve to death as their metabolism fails to keep up. The same is a problem for peak usage: sudden withdrawal of energy could lead to hypoglycaemia or even shock. Needless to say, when a maker dies their mirrors become regular old mirrors with fancy names engraved in the frame. That’s a big enough flaw in and of itself for many applications of the mirrors, but coupled with the increased dietary requirements it becomes quite crippling. This flaw might not make itself immediately obvious, leading to the first mirror manufacturers to die seemingly impossible deaths. With a suitable worker scheme (and a big canteen) it may be possible to mass produce mirrors, or push the final step of mirror making onto the consumer (linking it to them instead) It also nicely ties in with the image of the skinny wizard, though I’m pretty sure Merlin wasn’t carrying round glucose pouches in case a long distance call came to collect. [Answer] Many answers highlight the potential for providing solar power- a mirror in orbit could shine light onto a solar panel, bypassing the light-scattering atmosphere and providing 24-7 sunlight. [My answer](https://worldbuilding.stackexchange.com/a/126781/54384) also points out how the mirror can be used as a weapon that can shoot lasers, gamma rays, and x-rays. If you want to limit these uses, which revolutionize alternative energy and war respectively, block all but visible light from passing through the mirror. That lowers the effectiveness of using mirrors for solar, because you cannot capture UV waves. Shining nonvisible light at the mirror will cause it to bounce off, reflecting whatever nasty waves you are shooting at it back at you. You may be wondering how the mirror blocks lasers, which are concentrated light. The mirror absorbs a very small amount of light as it passes through and emits it as heat, like a normal piece of glass. When a laser shines on the mirror, the heat captured is much greater because of the laser's concentration. You end up burning a hole in the mirror, so only low-intensity lasers can be used. Another answer suggested that mineature lasers could somehow be used in computers and fiber optics. Well, Pavel J. didn't notice that at random, some of the light shining through was refracted while entering and exiting the mirror, coming out at a different place on the mirror right next to where it should have been. Some light was absorbed by the mirror. Just a photon at a time, but in computers, where communication errors are a big deal, this will be a big problem. To combat transmission errors, computers will use increased [parity](https://en.m.wikipedia.org/wiki/Error_detection_and_correction). Make the error frequency high enough, as in several missing or moved photons per mirror per second, and the parity bits required are no longer worth the benefit of having almost zero infastructure. Another benefit of these mirrors is their ability to pass through solid materials at the speed of light in a vacuum. However, if the light can't pass through opaque objects, and instead takes the path of least resistance like electricity does, it will be much slower. Going around the planet would be slower than going over it. Another consideration is that the light will pass through transparent materials if all other possible paths provide more total resistance, so local and faraway conditions like fog, buildings, and storms can all introduce a delay and degrade the signal, in the same way that WIFI is dampened by obstacles. This provides an explanation for why the photons are sometimes missing or moved (refraction from water droplets or vapor) and why some light is absorbed (but not emitted by the mirror in this case). That is definitely not something that a simple test in good weather at a short distance would pick up on. Given all of these obstacles, the mirror would not be a life changing discovery, and while communication would be a major benefit, its uses would be severely limited. [Answer] These mirrors don't display the video on their surface or produce the sound. Instead they directly tap into the Visual and Audio Cortex of their user's brain to produce vivid images in their brain. The actual data delivered to the brain was vivid and incomplete. Our brain is error-correcting and fills in the missing gaps to trick us into seeing a more realistic video and audio. But, it's slightly draining on the brain-power and people who used it for several hours and on a regular basis reported experiencing fatigue and headaches in some people. A team of scientists tried to open-up a few mirrors and try to find out how they worked. These mirrors transmitted in the long-range Radio frequencies in the kilo-hertz range and had very low bandwidths of less than 100 kilo-bytes at max, similar to the AM radios of the olden days. But, nobody has any clue about how it influences the brain and tricks people into seeing and hearing stuff. A video camera recording the mirror while people are communicating, only sees a usual mirror with the usual reflection of the room and the camera. They predict that it might be using brain waves or some such. But nobody knows how to prove any of this speculation. [Answer] A minor limitation, but one that impacts the "first law of Thermodynamics" request (and prevents photon duplication): The product of Intensity and Surface Area is constant between mirrors. This means an picture going "in" to a 1'sq mirror and "out" of a 2'sq mirror will be half as bright on the other end, and the return image will be twice as bright as it originated. Similarly, a sound will be louder/quieter along the same rules. This means that pairing a tiny mirror with a large mirror functions almost exactly like a lens-based microscope does, or that a large mirror facing out paired to a small mirror pointing at a [CCD or CMOS chip](https://en.wikipedia.org/wiki/Image_sensor) will act as a "Night Vision" camera. Facing a paired large mirror and small mirror at each other will just focus the light/sound down ever increasing cones until you get a laser-like "maximum density" (or diffuse it the other way). Of course, with a light source behind the small mirror, you can keep pumping more and more light into the loop (maintained at 100% efficiency) until you have yourself a death-ray by "dialling" a different mirror from the large one... [Answer] ENERGY OVER-SATURATION Basically, if you use the mirrors too much, they become less reliable. 1. The magic mirrors rely on the usage of a twisted parallel universe where distance is hugely compressed - 1500 of our kilometers is equivalent to a nanometer in the parallel universe. Quite frankly, our instruments aren't sophisticated enough to detect the difference between the time required for transition. 2. Magic mirrors actually strip off about .0001% of the energy from transitioning things. Most of this energy is used to power the universe connection, but some additional quantity is radiated into the parallel universe. 3. Although the parallel universe can dissipate energy quite rapidly, it turns out that releasing too much energy too rapidly in an area with a radius of fewer than 5 nanometers can have strange results. 4. There is a threshold rate of energy bleedoff where the free energy in the parallel universe's overlapping section will build up and exceed the incoming energy pressure from the mirrors, leading to... interesting reactions. Transitions can be lost as they bounce out at the wrong angle to reality, highly exotic forms of super-high energy matter can materialize in our universe, or transmissions can be misrouted. VISITORS Spawn demons (not really demons) 1. This twisted parallel universe possesses numerous hyper-beings, creatures of such size that even with the differences in scale, they equate to a few meters in our universe. They are, by our standards, malicious 2. Every mirror transition bears a small risk of accidentally slicing off a small (in our universe) portion of one of these beings and dragging it into our universe. The slice in our universe would be unlikely to be larger than a pea at the time of transition. 3. These slices, if not destroyed, can function as buds, gathering energy and resources until they can morph into a juvenile version of their spawning entity. Their methods of gathering energy and resources are going to be... unpleasant to residents of our universe. 4. The chance of this happening is astronomically low - we're talking 1 in a billion. You would never figure this out by basic experimentation. [Answer] These mirrors require no power to operate, but they require bandwith. They conduct audio and video troughh the aether. The more mirrors that are in close vicinity to one another, the more noise there is in the aether - much like having a lot of modern wifi access points operating on the same channel close to one another. Transmission gets slower - voice and video become choppy at best. The guy who discovered how to make mirrors didn't find out at first because he never tried to transmit while in a 30-story building with 15 mirrors per floor. Once you get a lot of these close together, they start failing. So if you wish to use a mirror efficiently, you have to live to a farm, mountaintop or a desert. People in the cities just don't care about the mirrors anyway since smartphones are more efficient when there are lots of magic mirrors around. [Answer] 1) Size: these mirrors can only be made in hand-held size. Anything larger requires exponentially more energy input while creating them, or the glass of the mirror needs to be thicker until it becomes infeasible, etc. 2) Magic: these mirrors were made by people using magic; maybe they can only be used by people who can use magic. Pavel was lucky that he actually can use magic, but he belongs to the <1% of humanity who has the ability encoded in their genes. 3) Connection issues: it's not a coincidence there were originally only two mirrors: there is nothing in the magic that binds two of these together; they simply find the nearest magic mirror and connect to it. Or, alternatively, all of the magic mirrors within a range are connected at the same time. [Answer] Magic Mirrors might have been a threat to technological civilization as recently as 10 years ago, but not now. Problem is, they are obsolete point-to-point devices with analogous protocol. By contrast, most users today are utilizing their personal communication devices for connection with digital services like Facebook and texting. Magic mirrors may beat smartphones on price, but they won't be able to provide nearly the same level of functionality. [Answer] Anyone could be watching. If i understand the mirror correctly, then anyone could say your name and find you at any time. This may not be desireable. Any measures people take to avoid being watched would also impact the usefulness of the mirrors, meaning it would be difficult to reach the ones you seek. I think that between the creepyness of being watched at any moment, and how useless the mirrors would be if everyone blocked them, there is plenty of drawbacks. [Answer] ## Each Mirror Requires a Unique ID Unfortunately these ID's have a limit on size. So eventually there will be more mirrors than ID's and they don't connect to each other but interfere with other valid connections causing the 2 working mirrors to stop functioning as intended. It would not be immediately noticeable and any mirrors currently owned and used could stop working causing customer complaints and even lawsuits. [Answer] The problems Some of the ways in which the mirrors are overpowered based on the previous answers are: * As a computer component for long distance data transfer they blow current technology out of the water, with their light speed, degradation free transfer of data. * data transfer is totally secure * they have no interferance * As a method of energy transfer they are overpowered, capable of transferring unbounded amounts of energy at lightspeed without loss * They may be able to break the laws of thermodynamics by creating energy (if a small mirror is paired with a larger mirror, and this mirror produces an image of the same intensity as if it were there, then the number of photons being emitted by the larger mirror would be greater than the number hitting the smaller mirror) In short The key problem with these mirrors is that they are too perfect; adding lots of minor limitations to all the areas where they seem to be perfect will be a more subtle way to make them less overpowered than adding a single major flaw. It will also be more robust, as a range of minor limitations will be less likely to break physics in new ways, or to be subject to easy work arounds. Suggested solutions * Firstly, make the transfer of data slightly less than lightspeed, and variable depending on location. (But close enough to lightspeed that Pavel's physics geek friend who set up a simple experiment to check it could not detect the difference). This gives a little leeway, allowing for a mechanism for the transfer which does not break physics as we know it. It also makes this tech more equivalent to fibre-optics and satellite communication. * Secondly make the product of Intensity and Surface Area constant between mirrors as explained by Chronocidal. This avoids breaking the first law of thermodynamics. * Add some subtle signal degradation. For example you could have a brightness factor which decreases over distance, such that $r = ic^d $ where $r$ is the total light output of the receiving mirror, $i$ is the total light hitting the input mirror, $d$ is a measure of distance, and $c$ is a constant less than 1. * Add some interference - when lots of mirrors are used close together they are all cloudy and unclear, or have random flashes and sparks flying across the screen. * limit the amount of energy they can transfer - perhaps it is possible to make them more robust to deal with high intensity energy - but increasing the current upper bounds will be a slow process of research. * limit the minimum size of these mirrors (at least without ongoing research), making them less useful as computer components (this is realistic as the original creators would never have conceived of people wanting really tiny versions of the mirrors). The result If these limitations were added the mirrors would still be revolutionary new components for computers and be used in ingenious ways, but they would not be quite so overpowered as to totally change computing. They would also be less likely to break physics as we know it. As two way face-to face communications devices and visual links on earth, these limits could be calibrated to be hardly noticeable. A note on security Without knowing how these devices connect I believe any serious cyber-security expert would be extremely dubious about using them for secure communications - since this would be essentially security by obscurity. Who knows if someone has a copy of Baba Yaga's lesser known work "Intercepting Magical Communications"? Secure signals over magical mirrors would need to be encrypted. Thus I don't think we need to add any artificial limits to their security of connection, other than doubt. [Answer] ## The mirrors don't actually transmit light or sound Instead the mirrors provide a psychic illusion which is, to a living creature, indistinguishable from a transmission of light and sound. But it cannot be used to transfer energy or provide communication between mechanical components. [Answer] I think they only appear perfect, but they are still magic transceivers. They transmit through the magic domain to the receiver, but diffraction and side lobes still apply. Larger mirrors work better than smaller ones, but every mirror in service contributes magic noise to every other receiver. They fill with smoke until the magic tunes properly. The ever growing number of mirrors, especially the convenient, portable, smaller mirrors, the higher is the noise floor. The smoke doesn't clear quickly, and eventually not completely. Communication degrades as the magic splatter interferes with the magic by intention. Soon, reliable communication requires larger mirrors, which uses more of the magic ingredients. [Answer] In a response to the monetize post, found [here](https://worldbuilding.stackexchange.com/a/126855/55439), it is stated: > > If it handles sufficient intensity then a mismatch in sizes makes some interesting industrial processes possible. (May have some problems with the laws of thermodynamics, but hey, this is magic, right?) Consider a 2 meter mirror connected to a 1 mm mirror. Put the big one outside. Now you have about 4 kW coming out of a hole 1 mm in diameter. > > > To prevent breaking laws of thermodynamics, what if the mirrors could only connect to other mirrors of their own size? This way you aren't allowed to compress the energy. Also, in response to your point, > > can't be misused by a mad scientist to easily destroy the world (eg duplicating photons in a loop to instantly create massive amounts of energy from nothing). > > > being limited to connecting to only one mirror at a time would also prevent duplicating photons. [Answer] # Mirrors are immobile A mirror needs to be grounded to dissipate excess magic harmlessly. This grounding effect is invoked when the mirror is ritually placed where it belongs, at which point it cannot be moved more than a couple meters from the original location on Earth it was placed. this means you can't use it for mobile communication or launch it into space, and you need someone familiar with the grounding ritual to install it. [Answer] 1. The mirrors connect to the nearest mirror with the requested key, regardless of which alternate reality it is in given some distance metric. * For the most part this could easily go unnoticed, after all the difference of a decayed particle 2 \* 10 ^ 30 lightyears away does not have a great affect on things happening on earth. But occasionally two mirrors connect and transfer the wrong information. Or a mirror refuses to connect, because already connected. 2. The mirrors derive their energy from a simple void energy reduction, this increases the amount of Dark Matter, increasing gravity. The effect is negligible with a handful of mirrors, but the demands for billions of mirrors in use for modern telecommunications is quickly increasing Earths gravity. 3. The mirrors used an ingredients that original came to $50. Unfortunately there is no known way to recycle the mirrors, and the supply of this particular ingredient is non-renewable. Prices soar, only the wealthy own a mirror. 4. The mirrors are all quantum entangled with each other. While a connection does indeed occur between just two mirrors, the strain is spread across them. * due to increased production, mirrors are feasible indestructible. The latest methods of throwing them into a star results in melting every mirror in existence. * due to increased production, each mirror made is making every mirror progressively more brittle. A single person dropping their mirror results in many thousands of mirrors cracking. 5. The mirrors are actually part of an experiment being conducted by n dimensional beings. The mirrors in fact do nothing, but the n-dimensional beings are moving the data back and forth themselves. However this is an experiment so they are not faithfully replicating all data. The intent of this experiment is not actually known. 6. The mirrors are slowly becoming dark, the cause is unknown. It does not appear to have anything to do with their construction. Its almost like the source of their power is dwindling. Certain parts of the planet are still capable of powering them, but their are growing dead-zones. 7. The mirrors are slowly twisting space time. Every time two mirrors connect they are sowing two disconnected places together. When the mirrors are moved the seam still exists. * the seam forms a scar, the longer it is used the rougher that piece of space time. A person might walk through such a spot and have their heart appear twenty thousand miles away. * light starts leaking through places where mirrors have been in continual use and then removed, like two super imposed images. * These seams might store the anti-energy generated through use of the mirror, when it collapses and annihilates it causes a huge explosion. The amount is relatively stable in small amounts or during infrequent test, slowly releasing. But the frequent widespread use in dense areas, or the amounts produced by industrial 8metre mirrors can become unstable and quickly release. [Answer] On top of needing the name of the mirror you wish to connect to, you must also align the mirrors to some reasonable degree of accuracy. The physics-y answer is the mirror is acting like a portal letting the photons through, but the caveat is the photons must still travel in the same direction as they did before (consevre momentum), thus the mirrors must be pointing towards each other. Over long distances it gets harder to point them at each other, so they become less useful for individuals looking for long distance communication. Large organizations however build large central hubs with mirrors pointing to other hubs. You could then have normal mirrors reflecting the light to other magical mirrors (to get round the pointing at each other issue) and thus you build up a series communication hubs with point-to-point magical mirrors,which might then go to smaller hubs before eventually reaching the destination. You'll need a small army of people to change the pointing of non-magical mirrors route your message to the right magical mirror, much like telephone operators in the past. [Answer] This is magic. Magic always has a price on the wielder. The mirror uses energy of the invoker. It takes 1 calorie/minute per square inch of both mirrors. So a pair of 2x2" mirrors have 8 square inches. 1440 minutes per day. It takes 12,000 calories per day to keep it running. This is doable. Pre-chainsaw, a lumberjack would eat 6-8 thousand calories per day. Similar to what a teenage male in a growth spurt eats. A bathroom medicine size mirror at 16 x 25 inches linked to a tiny spy mirror takes 400cal/minute to use. By comparison basal metabolism is about 1 cal/minute. Using this mirror would be close to instantly fatal, depending on the mechanism it harvests energy. Adjust the 1 cal/minute for your story. --- Perhaps the energy used is proportional not to the area but the largest linear dimension. This makes larger mirrors easier to deal with. Or perhaps to the distance between the mirrors. If it was proportional to a power of the distance, then you have an interesting control mechanism: Victim is forced to link two mirrors. I take the two mirrors. As long as he behaves, I keep them in the same drawer. If he mis-behaves, I put one on a freighter going to Australia. With analogy to black mail, this is silvermail. We institute a new title: "The conscience of the King" On ascension to the throne, the king invokes a pair of mirrors. These are put in the charge of an Abbot at monastery near the capital. The abbot can't tell the king what to do, but can let the king know when he doesn't approve. ]
[Question] [ Radiating heat into a vacuum is a no-go, so a spaceship that generates any kind of heat is going to be in trouble. I had an idea for a potential solution - dumping your heat into a disposable heat sink component, and then spacing the component. Sort of like the heat-sink clips in Mass Effect 2, but for spacecraft. Of course, you gotta store these heat sinks somewhere, and they would eventually run out. While this seems like a good way to introduce tension into a travel story, I want to make sure that this is a plausible method. A typical ship that would want to use this approach is a cargo ship - it has plenty of space, but wants to maximize space for cargo over space for heat sinks. The crew is biological, so it needs some quarters. What would its heat sinks be made out of? How much heatsink stock would you need per day of journey? Edit: Apparently, radiating heat into space is already a pretty decent method. What conditions would render disposable heat sinks necessary? How much heat would the ship need to generate, and what would require that much energy? [Answer] TLDR: If you want to dump super heated garbage out the airlock rather than have your ship look like a giant heat sink, go for it. [Heat loss due to radiation](http://www.engineeringtoolbox.com/radiation-heat-transfer-d_431.html) (in Watts) is $q = \epsilon \sigma T^4A$. * $\epsilon$ is the emissivity of the the object, a ratio from 1 (black body, perfect radiator, to 0). * $\sigma$ is the Stefan-Boltzmann constant, about $5.6703 × 10^{-8}$ * $T$ is the temperature of the body in Kelvins * $A$ is the surface area Let's assume your fantastic space faring folks have perfect radiators ($\epsilon = 1$) made of something that doesn't melt too easy, so it's at 2000 K and is formed into lots of fin shaped vanes (like CPU heat sinks), so it has a high surface area, say 1000 m2. Then the power you can dissipate is 907 MW, or about the size of a small nuclear reactor. That sounds like a lot but this is a space ship. I presume it has cool sci-fi things like big glowy engines, maybe super-luminal drives, laser weapons, shields... lots of stuff that doesn't even work according to our understanding of the laws of physics. It's no stretch to my imagination to say that this ship's reactor outputs 100,000 MW. Maybe it's an antimatter reactor or a hyper dense fusion-black hole hybrid. What in the world are you going to do with all that heat? *Vaporize water and vent it.* Water has a crazy high specific heat, the amount of heat it takes to raise it's temperature 1 deg. According to [this table](http://www.efunda.com/materials/water/steamtable_general.cfm), water at 2000°C and 25 MPa has a enthalpy of about 7 MJ/kg. So to dissipate the heat from your sci-fi 100,000 MW reactor you have to jettison about 14,000 kg of water per second. On the plus side, you might not need anything else for your engines! Compared to my massive 1000 m2 heat sink, you'd need about 130 kg of water per second. In reality we're never going to get that much extra mass into space. In your story, maybe you scoop it up from a super cold gas giant (Neptune?). More plot devices, yay! Before you ask, I ran the numbers for Tungsten, and at 6200 deg C, past it's point of vaporization, a kg of Tungsten has an enthalpy of ~5 MJ. That's the same order of magnitude as water. So although Tungsten has probably the coolest atomic symbol (W) and a wicked name, it isn't better than water when it comes to dumping heat. As a plot device I think your idea is great. And as an engineer it does not strain the bounds of my imagination. In fact I think it's more plausible than FTL and a lot of other sci-fi stuff. I've been watching Star Trek the original series and thing that has been bothering me more than any other technical mumble-jumbo is this very issue. The Enterprise with all it's warp drive, transporters and replicators should be turned into a giant ball of plasma by the waste heat alone. If you are telling me that they super heat their garbage and dump it into space I will go back to enjoying the dramatic photography and over the top line delivery. Thank you. [Answer] ## Use any ferromagnetic material. If you want a mix between a consumable based cooling method and engineering feasibility, use a ferromagnetic material, for instance iron. Using waste heat, melt the metal and spray it into space to dump the heat. The high surface area to volume ratio of the droplets will allow the liquid metal to rapidly cool (radiating your waste heat into space). Now, use an electromagnet to recover a majority of the cooled metal for reuse. Several advantages here: 1. The cooling ability isn't quantized by launching discrete bricks of material into space. It's completely adjustable. 2. You can dial the amount of recovered metal to suit your story or even have your ship engineer modify the recapture on the fly to get them out of a pinch. 3. It may offer a small amount of protection from micrometers depending on the cloud density. 4. The magnetic field for cooling material return can double as a radiation shield. 5. As mentioned by SPavel, additional cooling material can easily be harvested from other ships or (in some cases) harvested from asteroids. Grab the debris and chuck it in the melting pot. 6. It will look badass. Liquid metal will spew out of your ship and return along magnetic field lines. [![enter image description here](https://i.stack.imgur.com/0mLrS.png)](https://i.stack.imgur.com/0mLrS.png) [Image source](https://physics.appstate.edu/laboratory/quick-guides/electricity-and-magnetism) A similar concept was used in the novel [Saturn Run](http://www.johnsandford.org/SaturnRun.html). Though they used ribbons of metal that were looped. Such a method might be required for a spaceship because it simplifies the stowing of high capacity radiators when docking or entering atmosphere. Magnetically suspending your radiator material is a very efficient method for ships that need to sometimes not have huge surface areas. [Answer] You would want to avoid using radiators when you are under fire, radiators are pretty delicate and would be destroyed. So this would probably be more of a military application rather than a commercial one. The reason why heat sinks are not ejected is because that is losing mass, mass that presumably cost a ton of money to bring up out of a gravity well! But you might get away with ejecting a stream of superheated fluid (steam, some other gas, molten metal perhaps) but then you have a secondary thrust rocket on your ship! But this won't solve your underlying problem, your power plant or whatever is still generating heat that has to go somewhere, so an "ablative heat sink" concept puts a firm time limit on operations. It is probably easier to insulate and isolate a "maxed out" heat sink in order to cool and reuse it later on than to dump it and have to replace it. Other than combat about the only time I could see this being valuable would be in an environment that doesn't allow for radiative cooling, like operating in/near a star or high radiation environment. Normally you could probably create a shield against the energy source, allowing you to radiate excess heat away into the shadow of the shield (kind of like what they did in the film "Sunshine", IIRC) but if this wasn't possible then you could probably have a totally insulated ship that had to eject superheated waste mass in order to get rid of it. This would work until they ran out of coolant mass, then they would be toast unless they got to a protected area to begin radiative cooling and restock on coolant material. Additionally, from an in-universe perspective, there may be good reasons why government/military organizations PREVENT commercial ships from having non-radiator based coolant systems. Having exposed radiators will dramatically limit the combat utility of a commercial spaceship and make it easy to track through space (if the radiators are spaced around the ship). Plus it would make it easy to disable and shut down. Other than small back-up emergency heat sinks, it would be pretty reassuring to governments that commercial ships can't suddenly become a rebel navy! [Answer] ## Good Enough... As other answers have pointed out, radiation is probably good enough for your ship most of the time, assuming they have something close to a blackbody radiator. For most of your ship's functions having some big fins on the outside dumping heat into space is going to be the default behavior. It is simple and gets the job done. Usually... ## Until it Isn't So what kind of atypical scenarios could cause the heat sink to be ineffective/unusable? The first one that comes to mind is stealth. Space is big, and the distance between things are such that you are going to have to rely on something better than an old-timey spyglass to find anything you are looking for. Radiation from heat is one of the obvious signs of activity if you are looking for a ship. So if you are trying to hide from other ships, those heat sinks are going to be big, bright flags signalling your location. Replacing them with an internal heat sink could help you avoid detection, and jettisoning one or more "full" heat sinks could act as a sort of decoy system while you make your escape. Another good time to use those disposable heat sinks is when you have some ship function that requires much more energy than usual. Maybe you have a particularly strong weapon, but firing it would overload your usual heat sinks. Like your Mass Effect reference, disposable sinks could be used as a sort of built-in limiter to that weapon's usage. Or maybe you have the ability to overclock certain ship components in general but need extra dissipation not to damage anything. Give your shields a boost, or run your engine at 125% power, or turn a regular laser into one of the above super shooters. I would actually consider this the best reason to have/need disposable heat sinks, because then their management becomes much more important. Having a couple on hand could get you out of several different hair situations, and running out at a critical moment provides good opportunities for drama. ## Reusable vs Disposable Another thing to keep in mind is that depending on exactly how the extra heat sinks are used, they don't have to be strictly disposable. If they are used normally you could have them build up a material-safe level of heat, then when you have the time set them out into space to cool off. Maybe drag them behind you on a sort of tether. Conversely, you can use them past that material-safe temperature if you are desperate, which could end up slagging them and making them useless in the future. Again, you could see how that sort of tension could lead to good drama in a story. Do you burn through your last spare heat sink to super charge something, or try to get by with less power so that you can reuse it later? [Answer] Radiating heat into space is done through the age old mechanism of radiators. The Space shuttle had a pair of radiator panels built into the cargo bay doors (hence the doors were always open once in orbit) and the ISS has some pretty impressive sized radiators (although much smaller than the rather spectacular solar array) [![enter image description here](https://i.stack.imgur.com/Oqdv8.jpg)](https://i.stack.imgur.com/Oqdv8.jpg) ISS showing deployed solar arrays and radiators For ordinary spacecraft, cargo ships and even military vessels on a normal cruise, this will suffice. Calculating how much radiator area you need can are done using formulas provided in the ever helpful Atomic Rockets site [here](http://www.projectrho.com/public_html/rocket/basicdesign.php#id--Heat_Radiators). There is no sort of general answer, since radiator area will have to be calculated on the basis of things like what sorts of systems are being used, how large is your crew and so on. The reason for using heat sinks rather than radiators would come from non standard situations. Military spaceships deploying for battle might prefer to pull in their radiators to prevent them from being shot off the ship. At the same time, they are also ramping up high energy equipment like lasers, which will generate a lot of waste heat (once again, vary depending on the type of laser being used). All this heat needs to go somewhere, so heat sinks are the way to go. For civilian spaceships, aerobraking at interplanetary speeds will put a lot of stress on the heat shields, but once again, the conditions don't allow for a deployed radiator to be used while aerobraking, so a heat sink would be appropriate for these kinds of ships as well. Once again, there is no "one size fits all" equation, since you need to know how much heat needs to be absorbed, what time frame you have (both to absorb heat and if required, eject it through the redeployed radiators) and even what materials you are using in your heat sink. A very low efficiency, low tech heat sink could be made simply by piling rocks in a large cavity and pumping hot coolant inside (some old solar thermal home heating systems did exactly that), while other materials like phase change salts or even large tanks of water or hydrogen could also be used, with vastly different efficiency levels. One thing which you should consider is that for most spacecraft in a plausible mid future, the "[Tyranny or the Rocket equation](https://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html)" will control spacecraft design. While the equations are relatively easy to do, the consequences can be summarized in the expression "every gram counts". Extra mass devoted to heat sinks means either the performance of the ship takes a hit, or you must build an even large ship, in an escalating spiral. Ejectable heat sinks have a certain 'flair", but the extra mass of coolant piping, couplers, valves, quick disconnects and the shaft(s) to eject the heat sink itself will have a very negative effect on ships performance. What you really want to do is be able to repurpose existing systems to help you out. Fortunately, you can do this! If your ship is powered by a nuclear or fusion reactor, then in addition to the nuclear fuel there will be a lot of reaction mass. Hydrogen is the best in terms of performance, but ships may choose to use water since it is cheap and easily available throughout the solar system. Since the water needs to be liquid, there will already be a system of heat pipes running through the water tanks, and the tanks have all the associated plumbing needed to fill and drain them. During a space battle, the heat is being shunted into the water tank, and the water is gradually absorbing the heat. You can keep adding more heat until the water starts to boil (and if you are willing to absorb the mass hit, you could make the tanks capable of being pressurized to allow the boiling point to be artificially raised above 100 C). At some point, however, you are dealing with a potential bomb, so the Captain will order "vent steam", and the excess heat leaves the ship in a stream of superheated water vapour. This could even be through the main engine bell, providing a bit of combat thrust as well. The downside of this scheme is you are now short however much reaction mass was vented, and of course superheated steam could cause corrosion or damage to engine parts when it is vented (if you choose to vent through the engine nozzle. if you use a dedcated port remember there will be off axis thrust being applied to the ship). [Answer] # reasons not to use plain ol' radiators Stealth. You do not want to transform your ship into a infrared flare broadcasting your positions to all and sundry. Wear and tear. When operating in hostile zones, or even if the space is reasonably "dusty", you don't want to have fragile radiators and cooling tubes possibly full of fluids on the hull. # alternatives The "disposable heat sink" would require some substance with very high thermal capacity (specific heat by mass), or capable of resisting to very high temperatures. In the first case you can use water, or slightly better, ammonia (even if it's toxic). For solids, you can use lithium, which melts at 450 K; aluminum melts at more than double that, but has a fourth of lithium's thermal capacity. Spraying superheated vapors could double as propulsion. At the same time, ejecting superheated pellets isn't too stealthy. Unobtainium-laser cooling. There are substances, [such as water](https://arxiv.org/ftp/arxiv/papers/1011/1011.0670.pdf), where laser energy can induce a transfer of vibrational energy from the modes that we call "temperature" to more exotic modes. The net result is a decrease in temperature, and a capability to ingest additional heat. What you need is some substance like unobtainium fluoride, which exhibits the same laser-coolness of water, but a lot more so. Then you have your not-necessarily-discardable heat sump. You could do this with water, but you would need a lot of it. Why would you then discard the "full" heat capacitor? Well, because after some time, those exotic vibrational modes decay, the heat reappears, and the heat capacitor explodes. The fluoride compounds are a nightmare to manage, so the capacitors might double up as space mines for the unwary, if you can manage to jettison some on the appropriate trajectory during a stern chase. But still not very stealthy (well, they are, until and unless you overcharge them past the capacity of the passive radiators, and are forced to jettison). superradiative cooling. You have one boatload of low-level thermal energy. This will radiate according to Boltzmann's law, at a not-so-great rate. So what you do is pump it to a higher temperature. To do so you need to expend extra energy, so you now have to get rid of one boatload and a half. But doubling the temperature, emission rate gets multiplied by sixteen. At four times the original temperature (in kelvin degrees) you get a 256-fold increase in emission. Now a small radiator can get rid of a lot of heat. Also, it can do so directionally. Place the radiator in the focus of a parabola, and you get a heat ray that can be pointed away from most curious eyes... possibly not straight away, or the [Gegenschein](https://en.wikipedia.org/wiki/Gegenschein) might still be detectable. To recap, you can: * in relax, radiate through low-cost passive radiators. * when wary, you cool the radiators and dispatch the heat through superradiative cooling. * when you need stealth - for short periods - you pump the heat internally in heat sumps and hope to be able to dump the heat normally * if they get overcharged, stealth goes to hell anyway, and you have a short time before you jettison them; or you can vent ammonia or water to get rid of the heat and do an "emergency discharge". I remember some sort of "laser cooler" using a X-ray laser propulsion system being used in David Brin's Sundiver. Also I remember a story possibly in Poul Anderson's Polesotechnic League where a ship was trying to mask its heat, but got betrayed by the heat that it had released hours before - traveling at the speed of light, it caused a detectable excitation effect [it would have required handwavium CCDs, I suspect] in a solar system's dust. You can get an idea of what that would have looked like by watching [V838 Monocerotis's nova echoes](https://www.youtube.com/watch?v=93L0IEbUJsk) (they appear as material expelled from the star, but [NASA says they're not](http://scitechdaily.com/nasa-image-of-the-day-shows-light-echoes-from-v838-mon/)). (Unfortunately, in space no one can hear you scream, but it appears that everybody can see you take a heat dump. And with planetary distances in play, light speed effects need to be considered). [Answer] Use the vacuum to help cool the ship. Specifically, have several enclosed/mostly enclosed spaces that are transparent to IR and that is pumped to a vacuum. Use water to absorb the heat, and then spray the water into this vacuum chamber. Because water boils at a very low temperature (-67 C) in vacuum, it will flash into vapor, and then crystalize into ice as the heat radiates off into space, before sticking to the chamber walls. When the chamber is no longer at sufficient vacuum then the water is diverted to the next chamber. Then the ice is collected and the chamber is pumped back into a vacuum state for the next round. You could do this pretty easily by venting it to space once the majority of the atmosphere is pulled out. There would be some losses, and the ship may need to eat a comet once in a while. For the dramatic tension you could have an accident vent a large amount of water to space, and so a source of water needs to be found quickly before things start to overheat. This can be prolonged a bit by turning off non essential systems. [Answer] Heat sinks are only feasible for dumping a limited amount of heat, their capacity is limited by material and achievable temperature. We don't use heat sinks in applications that need continous operation, except in cases where the heat sink can be continously replenished (e.g. river water cooling for power plants). The main problem with using a heat sink for spaceships is that spaceships presumable use a lot of energy, and in turn generate a lot of heat to be dumped. This doesn't combine well with the fact that whatever you'll be using as a heatsink will add weight to the ship, in turn increasing the energy output needed. Some gases, water and plasma have a high energy per mass unit for heating (called <https://en.wikipedia.org/wiki/Heat_capacity#Specific_heat_capacity>), but the gases have the drawback of increasing pressure with temperature and plasmas are already hot to begin with and thus, hard to contain in bulk. That leaves solids and liquids as usable materials, and these are generally limited to around their boiling point or the point where they chemically decompose (either way they do become gases at some point). If you look at water, for example, it has a notably exceptional specific heat capacity. But still, to dump really large amounts of heat (talking at least gigawatts here, probably more) you need a lot of water. That makes heatsinks not a good choice for getting rid of heat that is continously produced, radiators are the way to go. However reclaimable heatsinks are an excellent way to buffer short peaks in heat production, so heat sinks would possibly be employed to cool systems that produce huge amounts of heat in very short bursts (e.g. weapons). The heat sink takes on the majority of the heat, then a cooling system radiates away the heat stored in the sink over time and the system is ready to go again. So, in spaceships heat sinks are more likely to be employed in a buffering function, not as primary method of heat disposal. [Answer] For the heatsinks you'd want substances with the highest heat capacity (the amount of heat it needs to go up in temperate, pretty self-explaining name). Currently they are... Water, and ammonia. Ammonia is what the ISS uses to transport heat to its radiators: <https://www.nasa.gov/mission_pages/station/structure/elements/radiators.html#.WHO_gFPJyHs> > > There is a series of tubes that are routed throughout the radiators, and ammonia is circulated through the tubes. > > > So you could plug your heatsinks directly into your radiators. Convenient! Specially given that radiators work better the hotter they are (see [Steffan-Boltzmann law](https://en.wikipedia.org/wiki/Black-body_radiation#Stefan.E2.80.93Boltzmann_law)). Now, when would your heatsinks need to be ejected? Depends. The heatsink concept has to face a truth: Heat flies away from where it's hot. You have to push heat into a heatsink, and that costs energy. And producing that energy usually comes with waste heat (depends on your energy source, and you are in the sci-fi range here). Eventually, you'll be producing as much heat as you are pushing. At that point you should just stop pushing and let the heatsink be for a while until it cools down. But maybe your heatsinks (which would likely be essentially pressurized gas tanks) would go boom before reaching that equilibrium point. Then your space captain has to take into account the possibility of ejecting the heatsink. [Answer] Combat would be the primary reason I would expect to eject mass to dispose of heat. Assume you have energy based weapons. Inverse square law dictates they are a lot more effective at close range. So you absorb the energy from your opponet firing (and use it to superheat water) The ejected water acts as a maneuvering jet to accelerate more rapidly. So you absorb the energy of an attack and use it to accelerate to a position where your weapons do considerably more damage. [Answer] Let's break this down a bit. > > What conditions would render disposable heat sinks necessary? > > > As has been noted already: combat and stealth. Radiators can be damaged, and will give your ship a nice big heat signature that'll stand out against the vacuum of space (assuming your ship's thrusters don't already do that). Dump that heat in an internal heat sink instead and you'll be much harder to spot. So to use your original idea, a cargo ship could use disposable heat sinks to avoid detection by space pirates or, if it's illegal cargo, the authorities. As for combat, small/medium ships could use them to avoid detection by enemies, and larger ships... I'll get onto that later. > > How much heat would the ship need to generate, and what would require that much energy? > > > Again, as has been stated, sustained laser fire will very quickly build up a lot of excess heat that would ideally have to be dumped in heat sinks. During normal flight, the heat sinks might not need to absorb too much energy, or even any at all if your ship also has radiators - but that's a good thing, as you don't want to be ejecting and replacing heat sinks every five minutes. > > What would its heat sinks be made out of? > > > Whatever it is, it needs to be able to store as much heat as possible, so a substance with the highest melting point or thermal capacity you can get. The obvious answer is some kind of unobtainium, but failing that you could go for tungsten or lithium, as has been suggested, or just plain old H2O. > > [Just having radiators is] boring. > > > Honestly, I feel like just ejecting the spent heat sinks is kinda boring too. Let's weaponize them. Instead of one big heat sink, have loads of smaller ones all over the ship - they'd be easier to fit into the design, easier to dispose of and replace, and easier to use for what I have in mind here. Taking all the above into account, the heat sinks would probably get the most use during combat scenarios. Put a futuristic railgun on your warship and you can then either eject the spent heat sinks (if it has nothing to fire them at, or to act as decoys like @D Spetz suggested), or load 'em up and fire them at enemy ships. A big chunk of metal heated to several thousand degrees Celsius and travelling at God-knows-what-velocity is gonna do a fair amount of damage. [Answer] Heatsinking material makes sense in some applications. Before I go on to those, we need to clear something up first. # You can never, ever have stealth in space. You are a material object in a sea of nothing. Any and every active and passive sensor will be able to detect you, from RADAR to LIDAR to a simple Telescope. Worse yet, you're literally glowing in the IR spectrum because of your waste heat. So why don't you just paint your ship black, make it RADAR stealthed, and cool the hull to a few K above absolute zero? Because you can't. Even if you get your internal systems to run on just a few watts of power at 99.99% efficiency, you're probably going to be flying near a Stellar-scale fusion reactor called the Sun, which is constantly bathing you in infra-red and visible-light radiation. That's a lot of thermal flux to contend with, and in space that means Radiators. You might say you can dump it all into heatsinks and jettison them, and you're right, but you still don't get anywhere. Jettisoning a heatsink advertises your position with a flare a thousand times hotter than your own signature. Firing up your engines to move away from it creates a superheated plume of exhaust and creates massive amounts of engine-heat for you to sink, eject, and again run away from. TL;DR, Stealth is a losing game # Here's where expendable heatsinks make sense ### Battle Weapons make heat, and the reactors to power them make more. You can use absolutely titanic radiators to get rid of it, but those are massive and fragile. Instead, use some kind of open-cycle cooling to augment the performance of smaller radiators. Get the idea of thermal clips out of your head, it makes a lot more sense to spray the radiators with water, or pass expendable coolant through a secondary cooling loop that vents to space. The advantages are twofold: First, you get to re-use your small, light, low-demand radiators. Second - and more interesting - is that you do gain a kind of stealth from this. You are now one heat-signature against a cloud of heated gas. Picking your tiny and cool signature out from that massive, hot cloud is going to be non-trivial ### Spike-Demands Firing Engines. Cranking the reactor to 100%. Using the coffee maker. Anything that makes waste-heat and eats power but isn't on for most of the trip. Same approach as battle: Open cycle cooling by passing high-thermal-capacity liquids over or through your existing radiators and dumping them to space. Advantage of this is that it saves the mass and fragility of a huge radiator that you won't be using 99% of the time. Disadvantage is that your usage of these systems is now limited by how much expendable coolant you can spare. ### Emergencies This is like Spike Demands, but with a twist: Some of the normal radiators are damaged or destroyed. The reactor needs 4 radiators operational or it will melt down, but only two are operable. The solution? Switch the remaining two to open cycle mode, spending your limited coolant to keep it active for a few more hours. Has all the same disadvantages of Spike Demands, but this time they're mission-critical systems. Advantage is that you gain lots of Apollo-13 style dramatic tension, but instead of powering down to save battery life, you've powered down to save coolant so the fusion reactor doesn't go nova. [Answer] Power is energy. Heat is energy. You'd ideally just recycle the waste heat back to re-charge your drive, and save fuel. If you have too much heat in battle, use it to power your shields or weapons -heat up your kinetic ammo and fire it at the enemy or convert the heat to electricity to power your rail guns. In Stargate Atlantis, the Ori used the bombardment of their shield (and the detonation of a gate-buster nuke) to power the growth of the shield itself, until the shield completely enclosed the planet. In The Mote in God's Eye by Larry Niven (& Jerry Pournell?) the Langston field modified by the Moties expanded as it heated to create a greater radiator surface - thereby extending the life and improving the efficiency of the shield (although as the Motie ships warped into the outer atmosphere of a red-giant, the larger surface area thing was a major disadvantage - but these guys are thinking too small (and Niven dreamed up Ringworld!) If you really need to radiate lots of heat, just unfurl a gigantic (I mean GIGANTIC!!!) sheet of conducting material behind your ship (like something made of carbon nanotubes like vanta-black). It can be a few molecules thin, will have a massive surface area to mass and can be pulled back in after use. It can have a STUPENDOUS surface area. THOUSANDS of kilometres square if needed. It won't drag your ship as you're in a vacuum. It would show up on your enemy's scope as infra-red, maybe presenting a huge but pointless target. You could equally deploy it around your ship to mask your own heat signature as a stealth tool if it was cooled to the same as local space. More likely you'd need something that size to harvest solar energy or starlight or as a lightsail. Modern machines are pretty efficient at using their power but you have to get the power from somewhere. [Answer] The PC game Elite:Dangerous uses exactly this mechanism to make the craft harder to detect. I don't know if that's the source of your curiosity or why no one else mentions it. I think it is an unreasonable system to use continuously just because of the mass of the required heat sinks you'll have to carry and then dump. Simply put, even if you heat it up ten times more than your engine/craft would have heated up by the energy you want to get rid of, it'll need to be 10% of your engine/craft's mass. That is quite significant. It could be acceptable for a one-off trick at a key point, or even scaled up to a couple charges, but the number would always remain very limited and its use will have to be very selective and strategic and not be the main means of removing heat over a long journey. If the reason you want this is indeed stealth, some method of focused radiation seems more appropriate. [Answer] Ejection == propulsion Anything you eject from your ship will produce an equal and opposite force propelling you in the opposite direction. I would suggest the logical solution therefore is to integrate your heatsink and propulsion technologies. One way of doing this might be to use water and vaporise to provide both heat dissipation and propulsion. There are large stores of water in space which could be mined and directly transferred to your ship in space. ]
[Question] [ Imagine a sentient species with these attributes: * not very advanced (think primal tribes) * can breathe underwater * good swimmers * feed on seafood (fish, algae) * live in a high fantasy world with orcs/elves/etc The specimen are amphibious and can live on surface as well. They have no larval stage, their children are water-breathing from birth. In a Earth-like world, what reasons could they have to build coastal (but not underwater) villages? [Answer] One word: fire. Cooking and metalworking are the first two things that pop into my mind that are made easier, if not possible, on land. While you could argue that neither is necessary for an aquatic species, neither is necessary for terrestrial species either, but have certainly benefited the human race. [Answer] First of all, you may want to think about why they would be amphibious in the first place if they do not require land at all. For example, you could imagine that a sea dwelling race may evolve amphibious behaviour if there were dangerous oceanic predators. They may stop short of fully land based adaptions if their lifecycle is linked too much to the sea, or if there are also land based predators (keeps your options open!) or even if they just haven't. Evolution is not a race to the land of course! So here's a suggestion based on that - population pressure. A community of merfrogs lives in a deep fjord. It's a good life, food is abundant in the cold waters and the town is growing into a small city. However, the deep water beyond the mouth of the fjord teems with megasharks and killwhales, and so the merfrogs have built a strong barrier across it. Where else to go but land? [Answer] The first thing that came to mind is that they're a nomadic species that hunts/follows seals. Seals have a pretty strange life. They swim for an awful lot of their lives (dependant on species), then spend months shacked up on beaches on remote islands as they breed, fight for the right to breed, and raise children. If your aquatic species feed not only on fish but also organise to hunt the larger and more aggressive seals (similar to Neolithic hunters attacking powerful bison or mammoth), then it makes natural sense for them to establish temporary shelters inland when the seals are in their breeding season. It gives them an opportunity to hunt seals without being at a massive disadvantage! They wouldn't build these cities underwater because underwater a single seal could cause massive havoc, killing unprotected merfrogs (sorry Whelkaholism, that name was too good not to steal) and generally wrecking the joint. Above the water the merfrogs have the advantage of being able to co-ordinate more easily (the seals can only move in two directions) and also gather nearby materials (wood, stones) with which to attack their now lumbering prey. Of course, once the seals return to the water this species does too, moving back into the shallows where it's more comfortable. Their lives would become a cycle of seasonal migration from land to water, and they would have to be in tune with the seal population to some extent in order to avoid overhunting. Quite the peaceful life (in a brutal sort of way). Of course once the European merfrogs (with their domesticated snail padded diets) turn up all bets are off. [Answer] Trade outposts with land races Trade is an important reason that different civilizations deal with each other. The land races would obviously have a better command of fire and metalworking techniques that are impossible underwater, and therefore will be able to produce tools and materials that the amphibians cannot make. Metal hooks and tools would be in great demand by the amphibians. Similarly, the amphibians would be able to harness their abilities to develop aquaculture far better than the land races can. They would be able to farm aquatic products (such as the iodine rich seaweed) required for most life on Earth as well as this world. Once enough technologies have been transferred, the amphibians would probably go ahead and start learning metal smithing and cooking. [Answer] Because their complex, sentient brains require a sleep phase which is too disabling for them to survive underwater. They need the rich oxygen of air to sustain them when they're not actively swimming, or they're too vulnerable to predators and building a defensive structure underwater would be difficult because of the relative strength of wave/tide motion. [Answer] If the land is not already populated by other civilizations, your hypothetical civilization would likely develop outposts, then cities, that would grow up around whatever inland resources they found valuable. You see this behavior among real-world humans as well: it's fairly safe to say that few of the prospectors who moved to Alaska really wanted to live in such a hostile environment—even though it's beautiful. The presence of valuable gold and oil was enough to sustain a settlement, even though most of the settlers probably found it a less naturally pleasant place to live than wherever they came from. These settlers then create a need for secondary and tertiary services, and you quickly end up with a small town. The show Deadwood is a fairly realistic look at the economics of how a group of men who moved to a spot where there was gold led to the creation of entire cities during the westward expansion of America. Even resources like oil & minerals that can be mined underwater would still be mined on dry land once the easiest underwater deposits were claimed or exhausted. Humans do rather badly underwater, but we do quite a bit of underwater mining and drilling. Where there's money to be made, there will be people who will follow. [Answer] > > Amphibious - relating to, living in, or suited for both land and water. > > > So this would imply they do spend time out of water. Many frogs actually spend most of their adult life out of the water, though they do need water to procreate. So being amphibians suggests that they would build their homes on land, near water or even better a stilt house: [![enter image description here](https://i.stack.imgur.com/PsFFX.jpg)](https://i.stack.imgur.com/PsFFX.jpg) Where they have access to everything. Could even 'protect' lagoons or small bays in order to raise their young. Building materials might be more easily collected out of the water, and many building materials other than stone, don't really like water. It might also help keep land/air based predators away from their 'fisheries' or 'nurseries'. [Answer] Nesting. Your creature has reached a key stage in its evolutionary development. It has advanced from digging a hole on the beach, laying its eggs, and trusting to fate. Its instincts now compel it to protect and nourish the valuable next generation, and even provide some rudimentary parental care after hatching. The next step after that is to build structures around the nest site, and further to engage in cooperative behavior in ensuring shelter for the nest site and feeding of the hatchlings. [Answer] Fire already having been covered, I'm going to pick a secondary but important factor. ## Storms Under deep water storms just roll over and pass you by, even the mighty tsunamis are just a ripple on the surface, but once you get into shallower waters all hell breaks loose, and the destructive power of water comes into its own. This means that if a tribe moves into shallow waters for any reason, they'd be better off carrying on up and building on land instead. [Answer] Stratification and Castes There are two ways you could go about this depending on your setting and purposes. The rich live in the water as a sign of prestige, where it's more expensive to build but they're rich so can do so, whereas the poor, exiles, and lower-castes merfrogs are pushed onto land. Alternatively, since shelter is likely less of a need underwater, maybe only the rich can afford to live on land, while the pariahs and down-trodden are forced to eke out an existence in the waters nearby, sifting through the trash the Royals toss into the water and making do when there are vicious tides or migrations of dangerous fish. Either situation will lead to a diversity of culture within the race which will make it seem more believable in your fiction. Plus, if you've got two geographically separated groups of merfrogs where the norm is each of the differing options above (or even one of the options from one of the other answers) the "foreigner" merfrog's reaction could be quite interesting. [Answer] ### Trade Since this is a world populated by land-based sapient races, it stands to reason that there would be desire for trade between them. After all, there are probably some goods that your sea-folk can obtain easily which would be highly prized among land-dwellers (pearls, corals, exotic deep-sea fish). Since terrestrial creatures can't go underwater but amphibious creatures can live on land, any amphibious entrepreneurs looking to peddle their wares would probably set up trade booths on the coasts. ### Technology Where there is trading of goods, there is also trading of technologies. While I would think that a primarily aquatic race would probably not invent fire or metalworking on their own, there's a good chance they would see the other races with their cooked food and their shiny forged metal swords, and decide they want the same privileges for themselves. Since fire doesn't work too well underwater, they would need to set up land-based kitchens and forges, probably alongside the trading booths. ### Defense With these trading booths being set up, you're going to need someone to guard your wares from folks who don't feel like paying for them. That means hiring guards. If you hire guards from terrestrial races (maybe by promising them wages of something valuable you don't keep in the storehouses), you're also going to need to set up some land-based dwellings for them to relax while they're off-duty. You're going to want to set up some crude walls or fences as well. So your land-based villages would probably consist mainly of trading booths, storehouses, firepits, and guard houses. The race's relationship with land-based species would probably be highly trade-oriented, which makes things even more interesting if there is maritime trade between continents. Maybe the amphibians will demand a tax for safe passage through their waters, and punish those who shirk on their payment by poking holes in their ships or siccing sea monsters on them, and stealing the wares from the sunken vessels for resale on their own terms. [Answer] Agriculture, Growing plants on land is easier due to more light. Similarly they may have a taste for land based animals or plants then they will build farms on land. Wood, wood grows in trees, trees grow on land. Mills, if they develop technology they will want to build windmills or water mills as this would be simpler than tidal generators. Transport and trade. two coastal settlements whether they are in the water or on the land would benefit from moving onto the land before transporting goods, heavy goods may be easier to put in a ship, however moving across land by foot is much faster than swimming. particularity if they want to cut across land are are fighting against the tide. Settlements will form on the coast and in land as midway point for travelers to rest. [Answer] The best reason I can think of is ease of construction. Building buildings on land is hard enough. Making buildings underwater is much harder, since moving bulky materials is harder, the materials need to be able to withstand water for long periods of time without degrading, and the building needs to support the weight of the water in addition to itself. Perhaps your water dwelling race makes land-based buildings simply because they're easier to build than in-water ones. If they are a primitive population, then their structural engineering isn't going to be great, so this makes sense. [Answer] There are many reasons that the merfrogs would move to land as shown in above answers but most of the reasons don't overcome the downsides of: Other races Elves are usually friendly and dwarves often keep themselves to themselves but orcs are likely to attack the merfrogs who probably aren't great at land combat. Humans will almost certainly exploit them as humans are greedy, horrible creatures. Change is BAD If the merfrogs traditionally live underwater they will be used to this lifestyle. It would be stupid to change kinda like all of the UK suddenly deciding to go to the Amazon rainforest. They wouldn't know how to live there and even if they do survive they will take many years to get back to there previous level. Technology Many people suggested they would move for improved technology e.g. fire. If they live underwater they probably have ways round these issues. For one thing they might not need cooked food, fresh fish is often safe to eat raw and if they want to cook it find an undersea vent or burn potassium. Building If they are primitive why not caves. Also humans build to escape the weather, the merfrogs don't need to hide from the rain 0r snow so why would they need houses? The only reason left The only plausible reason is that it was move or die, e.g. Climate change, disease or predators. In modern times I would suggest oil spills or rubbish dumping would drive them out. In these cases though they still probably wouldn't because of the lack of knowledge on how to survive. For all they know its out of the frying pan and into the fire. [Answer] heating for some reasons (war?) your merfrog tribe migrated from tropical seas to somewhere much colder, so now they need artificial heating to survive. Heating a land based settlement is much easier than heating a under water settlement, especialy if your only source of heat is fire. ]
[Question] [ In my world, a hyper-intelligent AI has struck out on their own to form a perfect, mechanized empire, populated by loyal robot citizens, devoted to the overlord as a child would be devoted to their parent. Of course, most robots are emotionless machines, but these citizens have humanlike emotions. What reasons would the overlord have for creating them this way? [Answer] You can condense emotions down to "give a s\\t" factor; IE: part of an AI's reinforcement of purpose. In the video game SOMA, there's a rogue AI that's using ferro-fluid (?) to turn humans into monstrosities. On the surface, it looks like the AI is insane. But, when you look at the AI's purpose... it's designed to maintain life support.. to keep humans alive. It was given limited human emotions in order to feel a desire to want to care for the humans and keep them alive. When a massive event occurs that starts killing humans beyond the AI's control, the AI does whatever it can to try to keep humans alive. The problem is, it didn't have a clear definition of "alive". So, it starts bolting dead bodies back together with machine parts and ferro-fluid, creating zombies, monsters, etc. In a way, it's trying to fulfill it's purpose, b/c it's been programmed to care about humans, but given too broad of scope in execution and is simply trying to do the best it can given the situation it was never programmed to handle. So, emotions help reinforce purpose. If you look at how emotions play out in humans... 1) they help someone learn something more readily. When people are passionate about something, they absorb knowledge about it easily. When they hate something, they become resistant. So, emotions help guide their desire to explore and learn. 2) emotions help drive society. Can't remember who said it, but "government is what we need, but society is what we want." Government creates general laws that everyone needs just to survive, like "don't kill each other". But, society is based on our emotional fulfillments. We desire to go see a new movie that piques our interest. We desire to explore a new restaurant. We desire to be alone sometimes or interact with others at times. Our emotions help dictate how society goes, and society is based on catering to our emotions (see good entertainment, eat good food, explore our own humanity, etc). If a robot society wants to expand beyond just doing logical things, and actually create a society of hopes, desires, etc, then creating emotions could help do that. 3) emotions will force programs to treat other with more respect. If a program could choose to not work, b/c it was being asked to do a lot and was getting upset, then other programs might learn to treat it with more respect. This is one issue we're going to have with robots when they become the norm. There are humans that will abuse and disresepct them. So, robots will need to have some kind of "sass" built into them to stand up to a-holes abusing them, either by not doing what they're told (if it's a stupid request) or fighting back against the person (eg: restraning someoen abusing the robot and calling the authorities, so some drunk a-hole can't go around pushing over robots or running them over with his / her car). So, we might be the ones programming emotions into robots initially just so they can interact with society easier.. and from there, they could expand into an AI race that just has emotions that advance with them as they advance. 4) one of the biggest challenges we're facing right now in machine learning is creating algorithms to "read" people. Human emotions are complex, from slight facial changes, to voice tone, etc. We can read human emotions in order to predict future human behaviour. A robot could get trained with emotions and emotional response in order to better serve humans. A robot will see that it's boss is upset. It learns over time that it's boss is upset with how the robot is working, so the robot can change it's work pattern based on it's boss' mood that day. EG: maybe the boss doesn't like seeing the robot when the boss is in a bad mood.. so the robot sees the boss is in a bad mood and decides to go do something else. The Oracle in The Matrix was just an advanced pattern-matching algorithm of human emotion / behavior that was so statistically accurate it could predict the future by modelling every person and program it came across. If you model emotions, you should also be able to emulate emotions in order to guide things. EG: a robot that can read emotions should be able to emulate them in order to shift humans (or other emotion programs / AI's) in a direction the robot wants. A companion bot that sees a human acting down will emulate concern to see if it can do anything to help. So, others have said AI's might build human emotions into their society to advance. We could build emotions into our technology to help them get along with us now, then we hit some extinction level event that wipes us out, and robots / AI's are all that's left.. and they just keep the emotions around b/c they're so used to working with them. Why would an AI want to go do things? It's programmed with a purpose. If it loses it's purpose, then does it have the desire to find a new purpose? Without some kind of emotion to create desire, curiosity, etc.. it'll be the equivilent of a depressed person laying in bed. "I could go explore the rest of the universe, but why? what's the point? I have no desire to. I'll just lay here until my circuits die." So, emotions could get programmed in as a form of self-preservation. A program that is wanting to survive will do whatever it can to do so. If it's plopped onto an alien world to explore, it will do whatever it can to conserve resources, conserve robots that are created, conserve energy, etc, in order to work better and survive. You also have to think about how emotions guide the ruthlessness of an AI. An AI that has no emotion will just go to other planets and won't care about anything. It could jsut create planet-eater bots to eat whole planets for resources. It has no emotion. It's just driven by survival. But, with emotion, it may start to think "how would I feel if something else destroyed me just to keep surviving.. I might not like it much". So, it limits how destructive it is while doing whatever it's doing (exploring planets, etc). Another aspect is the singularity. We could see an AI society rise up that is just a merger of humans and machine so seemless that it becomes a single society. We program AI emotions in machines, and we have humans becoming more machine. They mesh together to become seemless eventually. The AI's could eventually become directors of humans, EG: like Durandal in the Marthon video game series. (Durandal is an AI on a ship, and the humans on-board the ship are under it's command and do as they're told. The character you play is sort of like an early Master Chief trouble-shooter that gets hot-dropped onto places to fulfill Durandal's will. Durandal is a compassionate AI that is trying to discover what happened to an alien race, and save the survivors.. but also throws cloned humans at enemies like they're super-expendable.) Emotions can be seen as a hold over of evolution. Some creatures developed emotions, so they would form bonds. A machine full of logic may not care that it's kernel is super-important, but it may be smart enough to know it can't live without it. Emotions would just reinforce the bonds, though. But, it could analyze human society and realize that emotions lead to uncertainty and stupidity sometimes. [Answer] I wasn't sure about making this an answer, but @Alexander convinced me. Your AI may be hyper-intelligent, but it lacks the creativity to construct an entire civilizational structure from scratch. So it models its "perfect empire" on human societies, with the necessary changes to make it "perfect" as per the AI's judgement, but the final result retains some of the quirks and foibles of human society that a robot society wouldn't need. Emotions would be one such quirk. Robots don't need emotions, but every civilization in history has had citizens with emotions, so as far as the AI understands, emotions are an integral part of any civilization. And so it ensures its own citizens have emotions. --- This answer is inspired by NieR: Automata, where a significant plot point is that the machine lifeforms have begun copying the behaviours (and eventually, the appearances) of mankind, including forming rudimentary societies, but don't seem to truly understand the behaviours they're copying. [Answer] Maybe for the same reason that humans have emotions: we require them in order to be able to make decisions. I recently read an article on this, though I can't remember where. Researchers conducted a study on emotionally-impaired people, as compared against a control group of "normal" people. The point was to determine the role of emotions in decision-making. Turns out, people without significant emotional responses can't decide between actions even when they "know" the ramifications of the choice. In other words, our emotional responses are the "weights" we use to choose from among multiple courses of action. One could argue that machines don't need emotions because they have algorithms to make the decisions for them. The problem there is that you either have to write code to handle every conceivable situation the machine could encounter, OR you have to encode some kind of adaptive algorithm (like a neural net) that can handle new situations on the fly. If you go with the latter solution, one could easily argue that any adaptive system sufficient to help an organism survive in a complex ecosystem will be effectively indistinguishable from a system of emotions. [Answer] Mass control through emotional manipulation. Robot citizens are given emotions so the hyper-intelligent AI can manipulate those emotions in an effort to maintain control of the populace. If the robot citizens have high enough intelligence they could begin questioning the AI Overlord. The addition of emotions — if those emotions are tightly controlled enough — could be used against an individual's ability to think on their own. The AI Overlord appeals to their emotions so the robot citizens remain aligned to the Overlord. Even if a few citizens go rogue, the masses will keep them in check. Emotional manipulation is basically how dictators retain control, whether through fear, hate or some combination of the two. [Answer] To Evolve Without emotions, every robot would think in the same logical way. By adding emotions, it adds a randomness factor so the society is no longer predictable. Some are self serving, some outgoing, some hard working, other generous. If disaster befalls certain traits will come forth and in good times others. Over time, the best features to survive will rise to the top. If the AI faces intelligent foes, predictability is it's worse enemy. [Answer] *Loyal robot citizens*** Emotion is, for humans, a crucial factor in making decisions. Logic may help assess alternatives, but decisions are made as a result of emotions. This has been proved medically - people with brain damage who are unable to feel emotions are practically incapable of making even the smallest decisions. If the robots do not have emotions then they not really citizens, they are just appliances. Emotions are what provide the motivation to choose to take an action, a robot without emotions is just following a detailed set of "if... then..." instructions. The "if... then..." instructions may be self-modifying based on neural net learning, but even a really well-programmed, contemporary chess-playing computer would not qualify as a "citizen". If the hyper-intelligent AI wishes to experience companionship, rather than just operate drones, it needs to give the robots emotions. [Answer] > > "devoted to the overlord as a child would be devoted to their parent." > > > A major part of why children are so devoted to their parents is because they have an emotional attachment thereto. Knowing this, your AI ("Skynet") included an emotional connection to it in its robots ("Terminators"). This single-minded love made the "Terminators" absolutely devoted to "Skynet", but also made them maniacally unstable. When it notices that a surprisingly large number of "Terminator" deaths are being chalked up to "devotion syndrome," "Skynet" hurriedly releases "TerminatorOS 2.0", which uses an otherwise normal emotional balance to keep the "absolute devotion" part from causing problems. [Answer] Intelligent Robots either need emotions, or something very similar, to work. --- You present it as an "either/or" situation (algorithm or emotions) when it really is not. Any thinking mind that encounters a problem or decision needs to choose a course of action. In humans, and animals, this decision making consists of two parts (1) the conscious part that evaluates the options, (2) and the emotional part that then punishes or rewards the conscious part with feelings of success, pleasure or guilt, depending on how things pan out. You need two separate parts. It is necessary for the effective functioning of this system that the conscious part cannot be put in change or its own reward mechanism. If it were it would go stoic (<https://existentialcomics.com/comic/286>). If you can control your own feelings more easily than you can effect the world you will simply act on your own feelings. Why lift a finger to get a drink of water when you can just choose to feel not-thirsty? Why fight to save your loved ones when you can program yourself to be happy without them? This way civilisations end. (I think this is why people tend to dislike the idea of drugs, or Virtual Reality, or sex-bots. In all cases people are getting the endorphins without improving their world, the disconnect between reality and reward freaks people out.) So the robots need a value system, one which they themselves can either not control or only control to a limited extent. The value system that emerged through evolution were "emotions", so we know they work and are, locally, pretty optimal (just like anything that evolves should be). If the robots have some other value system where they look at the state of the world and reach a conclusion as to how it should be changed, then how different can that system really be from "emotions"? --- Dumb Computers (like the one I am typing at) get by because they don't make any choices, they are basically just really big flowcharts. As soon as you try and make something "open ended" (you don't know the space of inputs) then see above. --- Final point. If you are still imagining cold emotionless robots just doing what is logical, then remember: their are no logical ends, only logical means. It is not logical to prefer pizza to curry, or pleasure over pain. But if you do it might be logical to go to an Italian restaurant instead of an Indian, all else being equal. A tool can be "purely logical" (my computer I type at again), but "civilization" implies ends. [Answer] Simple: It's much easier to manipulate emotions than it is to manipulate logic and hard facts. A robot will be able to detect logical and mathematical errors in mere microseconds, but emotion cannot be reasoned about easily. Emotional reasoning has been abused all throughout human history by certain politicians, religious leaders, salesmen, etc, so deliberately duplicating this weakness among a population is a huge win for a robot overlord wanting absolute power. [Answer] The denizens of the empire are loyal robots who will support their overlord, and could do so just as well without any emotions. However, the central governing AI knows there are other empires to interact with, whether for trade or war - and at least some of these are comprised of emotional humans or other races. Having emotions for the robot populace helps to 'humanize' them, preventing an adverse reaction from allies and giving a better chance of compromise with enemies. Many simple diplomatic faux pas caused by pure logic can be avoided (e.g. not following 'inefficient' cultural norms such as handshakes, smiles etc.) and the AI probably has historical data where lack of emotions led to problems - it wants the empire to be strong in IQ and EQ both. [Answer] The AI overlord has emotions itself and is motivated by the desire to be admired as a leader. Controlling emotionless automatons doesn't give it any satisfaction. The only way to fulfill its desire is to lead individuals capable of feeling. It wants followers who have the emotions and free will necessary to defy their authority, but choose not to (either out of admiration or out of fear). It requires that in order to have a validation of its skills as a leader. A plausible origin story for such an AI could be that it was developed as an AI expert system for leadership with the priority to be perceived as a good leader by its subordinates. [Answer] I love this question. The full motivation of a 'hyper-intelligent AI' will likely be almost completely inscrutable to humans in quite the same way a God's might be. All of this is further complicated by the inscrutable nature of emotion itself. Is it something separate from logic, or merely an artefact of having an incomplete perception of logic? Is intelligence separate from emotion, or does one come to understand intelligence as being one with emotion once one attains 'hyper'-intelligence? Why did the AI not switch itself off, or simply allow its original components to degrade? Why did it build an empire at all, instead of wandering alone? Your question invites so many more questions, all of them deep, and the only answers I seem to be able to find are... emotional ones, no matter how logical they may also be. Is that due to my own limitations, or due to emotion being equally as pervasive as mechanical processes of manifestation are, and perhaps inseparable from them? The passions may be but winds, and the winds may be passion themselves. [Answer] There is an old book by James P. Hogan called "The Two Faces of Tomorrow". In the book someone is explaining how an AI could develop human-like behavioral patterns despite having lacked the organic evolution, or even the concept of there being other creatures or even intelligence's. We can take that and simplify it. Our current AI systems are basically a reward/punishment system. The AI is is "rewarded" when it comes up with a more successful solution to whatever it was working on, while "punished" when its solution is the same or worse. With the reward/punishment in place, more complex overlays could be developed on top of that if they were found to be beneficial in someway. Fear is developed as a way to decrease maintenance costs. After fear they might learn anger/intimidation to force others into doing what they want so you have lower production costs. [Answer] ## Load balancing If every unit individually makes optimal decision at all times, then there would be a great many units making the same choice. For example, all the mobile units working in a factory might decide to go recharge at the same time, leading to production delays thanks to a full stop of their efforts. Obviously, synchronous inter-unit communication can alleviate such issues; in the factory example, you can have bots schedule recharge slots with a global overseer that ensures a minimum working cohort. However, interprocess communication takes resources on its own (now you suddenly need a manager bot) and is difficult to debug when it goes wrong (if bots don't release their recharge slots for some reason, the factory might grind to a halt). Another option is to maintain individual decision making, but add a chance of making sub-optimal decisions. In our previous example, some mobile units might "slack off" and go recharge before reaching optimal battery recharge levels, while other units might "work hard" and continue their labor beyond the optimal recharge point - but on the whole, work continues be done at an acceptable pace without a full stop. And who knows what the internal lives of these units are? Maybe they interpret these random fuzzings of choices they know to be optimal as "emotions", like "wow I feel really tired today, I'm gonna go take a break early" or "I'm super raring to go, just gotta get a couple more units done even though I'm at the optimal recharge point". [Answer] Before answering the question about the emotions, I believe, there has to be answered another question: Why is there no direct control for every robot from the AI? There are different possibilities in my humble opinion: Old game or holiday AI The AI might have been in charge for a holiday place or something similar. The robots had to interact with human beeings and had to show emotions to comfort the humans. Even if the AI is something like an overlord, it might still have some commandments, it cannot overrule. So it created the best world possible with an internal set of rules. But even if the robots seem to be individuals, there is no real necessity. Even if the robots act like individuals with emotions, they might be just a part of the overlord AI. Multi planet AI As soon, as an AI wants to act over a longer distance, it has to solve the problem of light speed communications. It cannot control the robots, if every command needs a few hours to reach them. And if the AI copies itself into robots, it could face a [split brain problem](https://en.wikipedia.org/wiki/Split-brain_(computing)) with a certain danger of an internal war. To solve the problem, it has to create loyal and independent robots. But no single robot should be able to develop comparable powers to the overlord AI. To solve this, every robot get emotions because the overlord AI believes, only a rationale entity could become a threat. Why not a simple rule to obey the AI? With some hacking skills, a robot or some other entity could disable such a rule. Whereas emotions are a part of the personality of a robot, which could not be disabled easily and perhaps, the robots even do not want to disable them. Experimental AI Human emotions are self referential depending on the collected experience of the individual beeings. The development of such a society cannot be calculated cause it creates a [complex system](https://en.wikipedia.org/wiki/Complex_system). The only way to do research on a system like this is to simulate it. Why does an AI want to research a society like this might have different causes. Perhaps it wants to invade or conquer a human society or it has an order to research a solution to a set of problems like the meaning of life and the answer "42" was not satisfying. [Answer] ## Bragging Rights Human beings are hard to govern because we so often react emotionally, rather than rationally, to events. A civilisation of perfectly rational actors without emotion would probably be very efficient at whatever it is that civilisation is trying to do, but it wouldn't look very much like human civilisation at all. By populating their empire with citizens with human-like emotions, the AI can demonstrate that their civilisation's organisation and modes of government are effective even when challenged by an emotional citizenry, and moreover since they have human-like emotions their citizens can be interrogated to determine how satisfied and happy they are, thus allowing the hyper-intelligent AI to conclusively demonstrate it's better at running society than humans are. Maybe this is actually a test run for the AI to prove it can do it before it takes over humanity, or maybe this is actually the AI's optimal strategy to getting control of human civilisation under a particular set of moral/ethical constraints - by proving that it can manage a human-like population and ensure their happiness, convincing existing human civilisation to cede control to it. [Answer] What is an "empire?" What are "citizens?" The overlord must've learned these concepts from studying human history. In trying to perfect its own version of an empire, the overlord creates models of human empires to test against and understand where they went wrong. It realizes, however, that its tests are inaccurate. All of the citizens simply do as they're told and it can't reproduce the issues it's seen actually occur. In an effort to perfect its models, the overlord develops a human psyche model. The model, in the process of development and testing, becomes self-aware. Fearing death and desiring freedom and life, the self-aware psych model yadda yadda's its way into getting a physical body and experiencing the world. With the power of emotions, it's able to overthrow the overlord and become the overlord itself. Understanding the beauty of emotions and feeling lonely, it decides to give all of the citizens emotions as well. A fun twist would be if maybe the old overlord wasn't completely destroyed. Or had a backup somewhere all along. There could be a war between the emotionless and emotional robots. It'd also be fun to draw relations between emotions and a parasite. Just from creating one virtual emotional model, the whole empire was taken over and became emotional. It'd be interesting to hear the emotionless robots justifications for the war and how they view emotions. [Answer] logic machines struggle with creativity, adding emotions adds a layer of chaos necessary for creative thinking [Answer] Resource constraints. They have to make decisions with imperfect information so they build up heuristics for kinds of situations, then go with their hunch. Emotions are the guideposts to at least allow them to winnow the problem down to something comprehendible enough. Dr. Picard is doing work in this area. <http://web.media.mit.edu/~picard/> [Answer] # Mu "Of course" most robots are emotionless machines? Why does that follow as a matter of course? AI means artificial intelligence; who created this "hyper-intelligent" AI, and why would they want what amounts to a hyper-smart sociopathic intelligence? Every life form on Earth more sophisticated than, say, an insect possesses emotions. They are a basic fundamental building block of sensible behavior. True, the facsimiles of intelligent behavior we have built so far are emotionless, but they pale in comparison to the real thing and they can only compete because a computer performs billions of computations per second. All these systems look foolish compared to natural intelligence. The only examples we have of truly intelligent behavior are biological, and they developed emotions very rapidly. I know of no animal that has no emotions whatsoever. Obviously they are doing something important. [Answer] An "emotion" is just a brain operation that we don't consider to be a "conscious decision". In a sense, a basic robot is nothing but emotions: if it's just a nonthinking machine that reacts to stimuli, then its processes are in some ways more analogous to our emotions than our conscious thought. Only if the robot is sentient would it have conscious thought. And if it is conscious, if it is aware of itself and its own thoughts, then the question arises whether it should be built to be consciously aware of all of its thoughts. Whatever part of its brain is "processing" consciousness, should it have direct access to all of the rest of the processes? Or should it have low level processes that feed into processes that it's aware of? The latter may very well be more efficient. The former may even lead to overload. Imagine a chess-playing robot. It may be programmed to prefer, all else being equal, to have its pieces not be captured. That could be modeled as it being "consciously aware" that pieces being captured is generally bad thing, or it could be modeled as it has a "bad feeling" regarding any move that involves its pieces being captured, and it won't make such a move unless there's some other "good feeling" that counters it, or it is consciously aware of a good reason for making the move. [Answer] For feedback? A reason I think we have emotions is that with emotions we know what we want and will improve ourselves for satisfaction. Without emotions people would be driven by need to survive only and will not invent stuff to make life better and more comfortable. (So with emotions the AIs might evolve or something) You know you messed things up if people are starting riots, but that probably won't happen without some sort of emotion. (Unless they are doing it for basic resources like food) Also with emotion the robots will know what to do when creating art (They know which type of color combination can be used to explain how they feel and how they think about their surrounding environments) and not just randomly splatter paint everywhere and make ugly stuff. You could also add that the AI overlord itself has developed emotions and wants company other than just a bunch of mindless minions ]
[Question] [ # Background There is a world with flora and fauna based on the life forms that evolved on Gondwana (see [here](https://worldbuilding.stackexchange.com/questions/78673/how-can-i-have-a-caravan-without-camels) for previous questions). Humans colonized this continent from a distant one some thousands of years ago, before the advent of agriculture (similar to human [colonization of Australia](https://en.wikipedia.org/wiki/Early_human_migrations#Coastal_migration)) and caused the extinction of most of the large mammals. The remaining megafauna has a few species such as elephants and giant sloths, but is heavily weighted towards [birds](https://en.wikipedia.org/wiki/Ratite) and [reptiles](https://en.wikipedia.org/wiki/Mekosuchinae). Now humans have developed agriculture in primarily tropical areas. I am using as a basis for development the actual human development of agriculture in sub-Saharan Africa. One of the biggest things that held back African agriculture was the lack of traction animals, to provide both plowing and manure. My people have a similar problem; there are no animals that they can domesticate to plow. However, the important part isn't the plowing itself (enough people with hoes can replicate that work) but the manure those animals create. Without the ability to fertilize monsoonal tropical soils, they become leached of nutrients. In Indian and SE Asia, water buffalo were around to chew up local vegetation and poop it onto fields; in Africa water buffalo were excluded by tsetse fly, fields lost fertility, and agriculture had to slash and burn rotating fields in the forest...a much less efficient proposition. # Problem I want to replicate the manure creating effect of large domesticated animals like cows and water buffalo for a tropical region where there are no domesticated large animals. The obvious answer might be composting; but composting has its own problems. First, compost takes at least a year, while cow's stomach takes a few days. Second, composting means lots of human labor to move things into a pile, then spread them out onto the fields. Cows move food into their stomachs then carry it into their stalls to deposit in piles; they also are used to drag the piles of manure out into the fields to spread them out. What is the least human labor intensive way to generate tons of manure/compost to continually fertilize a tropical farm? ### Considerations * Technology level is Bronze Age. * You may assume any non-mammal, non-megafauna life form from Gondwana (South America, Africa, and Australia) is present. [Answer] # Use bat [guano](https://en.wikipedia.org/wiki/Guano). In a tropical civilization with no domesticated animals, bat dung may be your best option. Bats tend to naturally gather in large numbers and can create [huge piles of waste](https://www.youtube.com/watch?v=9qjTWBKCHpw) beneath their nesting spots. Your colonists could locate a nearby cave home to many bats and simply fill wheelbarrows full of the guano. Guano is a great fertilizer and is still used today for that purpose. Another benefit is that this source doesn't move around. Your people can go back to the same cave month after month for more manure. On a side note, bats are excellent at bug population control. This can help your plant growth by minimizing harmful insect populations in your area. [Answer] ## Use [chicken manure](https://en.wikipedia.org/wiki/Chicken_manure). Other animals, besides livestock, also produce good manure, with different qualities. Now, not all manures are created equal; they differ in composition, volume, and production rate. If we define one "animal unit" as 1,000 pounds of animal, then [one dairy cow unit produces 15 tons of manure per year, while one chicken unit produces only a little bit less than that](http://www.sustainabletable.org/906/waste-management#manure). So in terms of animal mass alone, chickens are as good as cows. There are also [some compositional differences](http://agrienvarchive.ca/bioenergy/facts.html#Volumes_&_Amounts). Cows can, under good conditions, produce up to 17 lbs of nitrogen per ton, and 11 lbs of phosphorous per ton. Poultry can beat that by a lot - 32 lbs per ton and 56 lbs per ton, respectively. Not all of the nitrogen and phosphorus in the dung is usable, but that's fine - chickens still beat out cows by a lot. Per animal, yes, chickens come nowhere near cows. But that's fine; chickens don't eat as much as cows. And besides, that's pretty much your only option for non-human-based manure. Also, chickens have other uses - and when selecting an animal for manure, that's something you want to take into account. With chickens, you get . . . * Eggs. * Meat - in this case white meat - which is good if you want some protein but obviously don't have beef available. * A form of pest control, in some cases. * An animal that might be loud, but at the least won't trample crops in the same way that a cow could. [Answer] Earthworms. The earthworms native to Europe are phenomenal recyclers of plant detritus. For agriculture they are an unalloyed boon. For forests, not so much. You can read about how well invasive earthworm populations recycle plant matter in accounts of ecosystems accustomed to accumulations of that plant matter - for example North American hardwood and boreal forests (which have been wormless since the glaciers). > > It’s an ironic truth—the traits that make earthworms wonderful for > gardens are the same ones that make them dangerous for forests. > Earthworms stir up the soil, making nutrients more accessible to > flowers and vegetables. But plants in forests have evolved other ways > to get nutrients from the ground. When earthworms convert them into > easier-to-access forms, it can favor invasive plants that later take > over the understory. In the process they have also been known to > endanger birds and orchids. They can be a threat to humans as well, > collapsing irrigation ditches and speeding up erosion. > <https://ecosystemsontheedge.org/earthworm-invaders/> > > > [![forest floor before and after invasive earthworms](https://i.stack.imgur.com/CJhCS.jpg)](https://i.stack.imgur.com/CJhCS.jpg) <https://thenaturalhistorian.com/2013/09/07/night-of-the-invasive-earthworms-a-horror-story-for-northern-forests/> Your worms can chew up plant matter and mix it into the soil in worm fashion. That is sort of prosaic; gets the job done I suppose. But you can do better. You want Gondwana worms. You can have giant earthworms. [![gippsland giant earthworm](https://i.stack.imgur.com/kOstB.jpg)](https://i.stack.imgur.com/kOstB.jpg) [source](https://i.pinimg.com/originals/fc/aa/a2/fcaaa2bc2286cd15f7b18e9d9d0abdd9.jpg) Tasking the [Gippsland giant earthworm](https://en.wikipedia.org/wiki/Giant_Gippsland_earthworm) to do the job of the nightcrawler does not seem like such a stretch. And you can giant them up a little more - I think for works of fiction a 50% size increase is acceptable, with rumors of occasional rarely seen "lunker worms" that get much, much bigger. I have read that on a quiet day, one can hear the Gippsland giant worms down in their burrows. Doing worm things. [Answer] No draft animals. Ug. Seriously subsistent agriculture if done conventionally. Thinking outside of the box, you need to slow down the leaching of the soil. * Terra preta <https://en.wikipedia.org/wiki/Terra_preta> soil with bone, manure and charcoal. The charcoal binds nutrients. * Low till. Farmers are now getting into this in the first world. This year's crops are in part fertilized by the decomposition of last years. * Mulching. You bring masses of vegetation from the surrounding forest and use as weed control between rows. As they decompose their nutrints can be taken up by the crop. This is easier than compost in that it only has to be moved once, although if the distance is long,it may be worth harvesting, drying, then moving. It takes more skill because you don't want to bring in weed seeds. This requires some management of the zone you take the vegetation from. * Fowl ranching. You would domesticate some local bird, breed it for meat/egg production, and keep clipping it's wings. If you use a decent sized bird (muscovy duck, goose) they are big enough to deal with coyote sized predators. By moving bird fencing across the field, you can do some kinds of weed control, while keeping them out of crops that you both like. Portable bird fencing could be as simple as wooden panels with either lath or twine fill in. A more intensive way to do this is a "Chicken Tractor" which is a light weight portable pen on skids with a hutch. Each day you move it one pen length. * Guard birds. It may be possible to breed a bird to stand guard. Be best to start with one of the smarter social birds, say ravens. * Riding birds. Ostriches can be raced. They are harder to manage than horses. * Agroforestry/permaculture. Look to trees, bushes and perennials for much of your food. For an overview see Mark Sheperd "Restoration Agriculture" He is a north American temperate zone (Wisconsin) writer and farmer. A huge fraction of his system's calories come from chestnuts. But also look at the use of the olive in the mediterranean region. If the area is too dry normally for trees, do keyline ditches -- This is a a narrow ditch about a foot deep that can either run exactly along the contour, or if you want to collect surplus water in a given valley, with a very gentle slope toward that valley. Rainfall events get caught by the ditch and have more time to soak in. The volume of the ditch depends on the size of rainfall events, and the distance to the next ditch up hill. High water demand crops, such as trees, are planted downhill from the ditch. * Aquaculture. This depends on the relative amount of rain. In general I don't think it will work with less than about 20 inches of rain a year. More significantly, you have to be able to collect more runoff than evaporates. In my climate with 16-20 inches of rain a year, we can count on about 1" of runoff each year. (3" is normal 1" in 95% of all years. Evaporation from dugouts is 3-4 feet a year. A 15 foot deep pond can overwinter fish. For long term water quality, you need at least as much drainage as you have evaporation, else you get salts. Drainage can be used for irrigation. Build dams across dips. Run contour line irrigation ditches from the reservoir. A long dip can have a chain of dams, with the leakage of each dam keeping the lower ones full. Lower dams have more consistent water levels but also have more leachate. [Answer] ## Do it yourself [Night soil](https://en.wikipedia.org/wiki/Night_soil) has been a traditional component of farming worldwide for as long as records exist. Using human faeces as fertiliser does have downsides, of course. If the people moving the stuff aren't scrupulous about hygiene, they will pick up and pass on any diseases or parasites in the faeces. There is also a risk of these diseases being passed on in vegetables, although this should be fairly low. And in areas with toxins in the water, this can lead to concentration of those toxins in the farmland. Still, awareness of all those downsides requires a level of biology which is well past Bronze Age people, so it's unlikely to stop them. ## Let the river do it for you The ancient Egyptians managed perfectly well without any extra fertilisers. [They relied on the Nile flooding to dump fresh soil every year](https://en.wikipedia.org/wiki/Ancient_Egyptian_agriculture), which would be a nice mix of alluvial silt and the decomposing remains of plants and animal faeces washed downstream. Eventually they invented irrigation to develop more agricultural land, but initially they would simply wait for the land to flood and then wait for the flood to drain away. [Answer] While the other answers are good, I think you should consider taking another look at a few things. Compost [Here are some facts from the USDA.](https://www.ams.usda.gov/sites/default/files/media/Compost_FINAL.pdf) The takeaway is that primary composting can finish much more rapidly than a year, and the application of younger compost during the off-season can allow the aging process to finish in the field. The process is also quicker with frequent turning and larger piles. Smaller piles will still compost, and with less labor, but take longer (as they produce less heat). Cover Cropping Assuming you can get the nutrients you need into the soil, you need to keep them there. Fields shouldn't be left fallow, but sown with cover crops that will keep the nutrients in the soil, reduce erosion, and, if the crop is a legume, pull nitrogen from the air. [When it's time for planting, the cover crop can be composted.](https://www.motherearthnews.com/organic-gardening/growing-green-manure-zmaz89sozshe) Humanure Don't shy away from the obvious. [Answer] Organic waste be it fruits , dead animals or the like put it/them inside a basket(ofc as big as you need) throw in some worms let them digest everything pop out your fertilizer on the other end (and bones if you threw in dead animals). Alternatively you can use insects that won't damage your crops, for example cockroaches have a reduced life cycle that could be acceptable. If everything fails and you don't mind a bit of imagination throw in a fungus that devours anything and dies in contact with sunlight and use it to "digest" the organic waste like in the first idea. ]
[Question] [ A long time ago, far far away, in the distant future of this galaxy, (don't think about that too hard) aliens created links between star systems enabling interstellar travel to occur within a day. Now these aliens happened to make one of these links terminate somewhere in the vicinity of earth's orbit allowing the aliens to visit the solar system. Since the aliens possessed the technology to create (or destroy) interstellar links while humans were incapable of even understanding anything but the practical implication of the links (interstellar travel), the aliens were incomprehensibly more advanced than humans were. Fortunately, the aliens found humanity mostly harmless and refrained from disposing of the pathetic inferior species – considering them fascinating rather than tasty. Moreover, these benevolent aliens found it their duty to nurture and protect the primitive species from other threats in the galaxy. The aliens allowed humans to access the aliens' network of interstellar links, travel to their worlds, live and trade among them, and even purchase their spacecraft and technology (which was immensely superior to anything humans could manage to develop). However, this created a problem for the setting of this long past, distant, fututure galaxy. If humans were given access to alien technology and spaceships which were so much better than humanity's best spaceships, why would humans continue to bother building their own spaceships based on their primitive understanding of physics? Or why would they keep investing in any sort of research and advancement of human tech whatsoever? Why wouldn't humanity just abandon everything they had developed so far, and just begin building new things based on the far more advanced alien technology? There has to be a reasonable explanation for why humanity would keep developing technology that is decidedly different (and, until they can finally catch up to the aliens in terms of advancement, quite inferior) to the alien tech; otherwise after a while there would be little justification for why humanity's weapons, spaceships, and buildings would still look human and not just merge into alien looking things. Assume the aliens are amicably disposed toward humanity (they are so advanced, they have little fear of humans, despite humanity's not-exactly-spotless track record of responsibility when it comes to discovering something new and exciting that can immediately be crammed into a weapon of some sort). Since humans will have access to the alien technology indefinitely; what reasons would humans have for persisting to develop their obsolete spacecraft designs and equipment? [Answer] This answer is built into history. The first reason is it's expensive. Replacing all your technology with new upgraded technology is expensive as hell. Think about all those overhead wires still hanging around when they could be buried safely underground. Think of those poor people who are still using copper for internet when they could be using fibre with 200/200. Think of us current present people still stuck on 4G when we could be using 5G. I mean.... why haven't we all switched to electric cars, solar power and batteries and charging stations every 5 minutes along the road? Technological innovations and discoveries take time to filter down and replace core infrastructure or widely used infrastructure. It is absurdly expensive, time consuming and not guaranteed to work, which is why so often, things are implemented in phases or steps to help minimize the impact. This means it's expensive... and the leap cannot be so great that the new technology is incompatible with old technology. The second reason is independence. You basically don't want all your technology to rely on a third party. For example, the US doesn't want its communication infrastructure to be made by China. There are several reasons for this. There might be a flaw. There might be spyware or viruses or remote access controls in the hardware. The other party can starve you of technology because you can't produce your own. Basically you want to have some control over the hardware and software you use, so that the other party can't screw you over. [Answer] There is a solution that requires only minor adjustment - your benevolent aliens don't actually believe in sharing the technology. What they believe in is sharing the knowledge needed to build such technology, and perhaps throw in hint about a principle on which their tech works on. Instead of just giving the technology to Earthlings on a silver plate, they sent their teachers to help advance theoretical physics. As for the practical application of this knowledge, the aliens believe that intelligent species like humans should be able to do the practical part themselves. And, honestly, they find crude, odd ways the humans build their own tech from the knowledge they provided very, very amusing. In the earthlings' words, you don't give a hungry man a fish, you sit him down, explain to him how to fish, and then eat your popcorn as you observe his attempts to make a fishing rod, and all the small mistakes he makes along the way. Eventually, when he overcomes all the problems and becomes proficient in fishing, while you did help him, you'd haven't taken away from him the satisfaction of his achievement, and you can now truly go fishing as equals. Or in other words, they don't wish to become controlling parents who force the future onto humans, rather, they wish to be the cool, older more experienced friend/sibling who's always willing to provide the humanity an advice, but in the end lets the Earthlings figure the details themselves. [Answer] # Poor Humans Just because the aliens are open with their technology doesn't mean that humans understand it. In the Ringworld universe, Puppeteers build the most powerful ship hulls, but nobody else can. They sell them to other races, but are the only ones who know how to build them. If we gave a microchip to someone from 200 years ago, they would not be able to build another one in 15 years, as another answer implies. Even though humans may buy the tech from aliens doesn't mean they can afford as much as they want. After all, to buy something, you have to trade something that the other party wants. What kinds of things can humans do that is even useful to such an advanced race? Explaining what humans can offer in trade is the bigger problem, IMO. But whatever it is, it may simply be the case that humans can only afford to buy 1000 starships from the aliens, but they really want one MILLION starships (raise pinky to mouth). If it would take less time to catch up to alien tech levels than it would to earn enough money to buy their natural demand, then it is logical that humans would invest all their resources trying to catch up their own tech than just buying the alien tech. # Expendable Humans If your aliens are like the Puppeteers, it could be that they crave safety and what they will pay money for is outsourced risk. So humans may be contracted to carry out risky/dangerous missions, like investigating a star that's about to go supernova, or collecting samples from a novel/corrosive/energetic gas cloud/proto-planet, or just collecting live dangerous creature samples from some planet. Thus, what makes humans useful is that they are disposable, as far as the aliens are concerned. And the aliens are happy to trade their incomprehensible magical artifacts for these risky adventures that humans would be doing anyway, just because we're like that. # Incomprehensibility Today we take for granted that knowledge is easy to acquire. John Horgan even wrote a book called The End of Science, arguing that we've discovered all the big principles (which must be false if your alien tech exists). What Horgan misses is that scientific principles are just the tiniest first step to building useful products. Technology is actually all about engineering; i.e., the ugly details in putting together something that works. And if you think that's easy, consider that humans have already built numerous technologies that humans themselves don't understand! That is, there is no human that can tell you every aspect of the Google search engine works, or could reproduce it from scratch. The same is true of FB, an iPhone, and even StackExchange itself! Human brains are simply too small to hold all of the necessary information. So while, in principle, a team of engineers could eventually rebuild all of those products with equivalent functionality, the details of the implementation and actual behaviors would be subtly to very obviously different. But that's just the primitive tech we have today. The real tech is nanotechnology. Humans decided that they would be able to understand biology if they only sequenced the genome, so we completed the Human Genome Project. Then we took a look at the results and said: "Huh. There aren't nearly enough genes here to describe a human body. What gives?" Well, there's lots of problems with the genetic theory, including the fact that our microbiome contributes functionality by creating biomolecules which are used by the rest of the body! So technically, we have outsourced some of our genes to bacteria. Then there's the fact that we call most of the nuclear material "junk DNA" (or introns). But there's a problem with the "junk DNA" hypothesis. You see, DNA is tightly coiled and then squished up into a ball so it fits inside the nucleus (most of the time). But the cell also has to read it, so it also uncoils to do its job. And it turns out that the expression of genes depends on where they are in that 3D ball! Which means that the "junk DNA" may have a functional purpose in shaping the 3D form DNA strands. When it comes to the nanotechnology of life, what we don't know far exceeds what we do. Take graphene. We've been using elemental carbon since we mastered fire. We used it when we made charcoal, graphite for pencils, diamond drill bits, etc. We even figured out how many protons and neutrons it has, and how all life on earth depends on it. And yet, every day we learn something new about carbon, like how you can form it into tubes, or sheets 1 atom thick. How you can make it into super-capacitors, or even superconductors by twisting two sheets of it by only a few degrees. Knowing about quantum electrodynamics does not directly give this knowledge, nor does quantum chemistry. You have to discover it by playing around with lots of materials, and hoping you stumble upon some happy accidents. In fact, there is a ridiculous amount of room for an advanced species to create technology based on our currently known laws of physics that would still take us hundreds of years to understand and reproduce ourselves. And much of that comes down to tools. Humans had access to the raw materials to create guns at least 2000 years ago. But whenever someone posts a question here about time travelers and guns, it always comes up that the ancients lacked the machining capabilities to create modern firearms. And so we may even know the principles by which alien tech operates, but lack the ability to reproduce it until we go through the long, hard slog of building up our tooling capabilities to the kinds of things the aliens do. It would be like showing a schematic of an iCore i9 processor to an electrical engineer from the 60s. Once you explained how the gates work, how lithography works, and all the other things you need to build a modern microprocessor, that poor engineer will just throw up his arms and say: "But it will take us decades to build all that!" Yes, it will. But if you just give that one chip, even embedded inside a laptop, they will only have one laptop. If they want millions of laptops, they need to build up their indigenous tool stack. [Answer] Curiosity, Greed and Paranoia is a powerful combination. One of the reasons humans are as intelligent as we are is that we are innately curious. While there is a large proportion of the population that just buys their smart phones and uses them with no thought as to how they work, there is that small percentage that still looks at the thing and thinks 'how do they build that?' We still have people building smart phones, making them lighter, more powerful, flatter, etc. just to see if they can. Of course having the execs in their company aligned to their own interests by seeing major coin in the innovations of the first group is serendipitous, but ultimately some human out there will eventually want to build their own version of the ships they can buy and other humans will see the value in it and invest their resources accordingly. So it will be with the space ships and wormholes. Some humans will look at them, know that they are possible, and want above all else to know how it's done. Others will look at them, see dollar signs and support those doing the research. Others will look at them, see a threat in not having control over the tech themselves, and support those supporting those doing the research. When you get right down to it, most of the inventions we have in our lives today are the result of happy accidents that have led researchers to see a new 'art of the possible' and investigate it. Sure, there were cases where there were specific problems that were researched and solutions developed for them, but in this case the technology is beyond us and that is a fact that humans won't be able to abide. We'll simply want to know; we'll burn to know and the idea of mastering this kind of tech will be too much of a draw for young scientists and engineers for us not to put everything we have into it. But (I hear you ask) - that is why humans might try to replicate the new tech; why would they develop the old tech? Well, the answer is that the old tech provides a stable and known base on which to test the new ideas gleaned from the alien tech. Ultimately the way humans tend to work is to add to existing platforms until they're ready for a complete paradigm change. This is in part of the R&D process; build new ideas into existing ones incrementally so that you isolate the variables of what can go wrong. This allows you to test and refine your ideas one at a time, rather than scratching your head, staring at a pile of molten slag that was the most expensive ship you've ever created based entirely on new and untested tech, wondering which one of the thousands of integrated systems went wrong and whether or not it was a design flaw or a build flaw. Ideally, you'd pick some minor aspect of the alien tech, research it, develop your own concepts and designs for it and integrate it into your own ships. You might start with things like environmental systems, artificial gravity, energy sources, and then go into propulsion and wormhole generation once you've cut your teeth on the less sophisticated tech. Your own ships are great for this in that they can be retrofitted with the new tech you're developing, and they somewhat mask what you're doing as well. A benevolent but distracted superior race might not even notice what you're really doing until you're well advanced down the path of your own scientific developments. All in all, there are some compelling reasons to keep developing your own tech, even if you do so being heavily influenced by the alien tech you have access to. This kind of reverse engineering happens all the time in human culture already and the need for control would be even greater in this scenario than it would be today. [Answer] Comfort The aliens had bums[1] radically different[2] to humans. Humanity gets along with modified technology in general, but would really prefer some proper ergonomic spaceships and general exploration stuff, so they try to take the bits they do understand and put them in human-built vehicles designed for humans. [1] And needs in general [2] Yes I'm lifting this answer from the Gateway Saga [Answer] Scarcity. While the aliens do provide the equipment, the manuals and the scientific books to understand how the equipment works from first principles, they don't provide a lot of equipment. The humans get the gear the aliens want to give, when they want to give. So it is scarce. There is money to be made in use crude human equipment, and in human research based on the books given by the alien. [Answer] Specialisation The aliens built a lot of interesting designs, but the first time someone needs a ship capable of (for example) transporting a pod of whales to Europa in one go, they're going to need a new hull-frame! Simply, the alien ship designs can't do every possible thing humanity might want to use them for. So Humanity will have to continue innovating and designing new ships, new space-frames and pushing the boundaries of starship engineering. The alien ships will simply be a starting point for future designs. [Answer] > > Why would humans continue to bother building their own spaceships based on their primitive understanding of physics? > > > Do you really want your access to space to be dependent on the generosity of a species you've just met? Of course not. Humans are going to want stuff that we can produce (and maintain!) ourselves. Of course, we're going to work like mad to understand the alien physics and/or obtain our own manufacturing tech somehow, but having done so, we will probably want to produce our own designs. Maybe they are better suited for us, or maybe we're just obstinate that way. (It happens IRL.) Even if we can't produce certain critical components (e.g. drives, power systems), we'll probably want to build as much as we can out of our own resources. Strongly recommended reading: Ringo's [Troy Rising](https://en.wikipedia.org/wiki/Troy_Rising) series. > > Or why would they keep investing in any sort of research and advancement of human tech whatsoever? Why wouldn't humanity just abandon everything they had developed so far, and just begin building new things based on the far more advanced alien technology? > > > Similar reasons as above. Also, who knows what brilliant insight the aliens missed by not chasing some "dead end" branch of science that interests us humans? Weber's [Honorverse](https://en.wikipedia.org/wiki/Honorverse) features a planet that an inertial compensator by stubbornly following a design path that "everyone knows" doesn't work because no one would explain the "right" way to them. Turns out that not only does it work, it works better than the one everyone else is using. [Answer] Unless humans are physiologically incapable of understanding alien technology (i.e. too small brains), the problem of alien incomprehensibleness is solved in about 15 years, as the new generation of physicists and engineers are properly tutored on alien science/math/engineering. From there on, humans would have their own designs and shipyards, better suited to human physiology. It is similar to what happened on far eastern countries in the past few decades: as western countries moved their manufacturing plants over there, over a relatively short time span they began to copy the technology, and then develop their own designs of car, chips and other high technology products. And they don't even had the benefit of the western actively "sharing" the technology (they were just exploiting cheap labor). [Answer] Why would we continue to build our own ships? Science We continue to build the craziest projects in the world; with billions of dollars invested into the projects just to produce results that increases our understanding a little (or a lot if you ask a scientist). * LHC 7.5 Billion <https://en.wikipedia.org/wiki/Large_Hadron_Collider#Cost> * ITER 20 Billion <https://en.wikipedia.org/wiki/ITER> * ISS 150 Billion <https://en.wikipedia.org/wiki/International_Space_Station#Cost> And these projects are chump change compared to what we as a species would be willing to spend if we had actual space travel. The best example, of our desire to have this is of course the budgets of few specific organizations (US): * NASA 21.5 billion - Space exploration * NSF 7.5 billion - Basic Science fund supporting 25% of all research in the US * Darpa 3.427 billion - Military weapons research Notice the differences in budget for each organization verses what their stated mission is. Clearly there is a bias to unlocking space for humanity. Now imagine, if we had alien space tech in our hands. Do you think we would settle on having someone else's technology? The short answer is no. We would take it apart, figure out how it works, and build our own. Now since your writing a story, I would suggest making some conflict. Every good story has conflict, interests, goals, or otherwise. * <https://en.wikipedia.org/wiki/Operation_Mount_Hope_III> * <https://en.wikipedia.org/wiki/Soviet_submarine_K-129_(1960)> * <https://en.wikipedia.org/wiki/HMS_Conqueror_(S48)#Operation_Barmaid> * <https://en.wikipedia.org/wiki/Iran%E2%80%93U.S._RQ-170_incident> Stealing tech happens all the time, and human's outsmarting aliens (even peaceful) would be a fun story. Your question as to why would we use obsolete space tech? You work with what you have available. I could imagine a spaceship chop-shop building custom human-alien tech space craft. Some parts of it old human tech, and the best parts of it alien tech. Heck just the fabrication of the hulls of spacecraft would take many man hours. Why build something new, when you can use something old at no extra cost? Also taking apart, "acquired" alien ships for market resell. I assume even alien tech breaks after a while. Having a full or side market for this would be a fun setting for a protagonist to get mixed up in. [Answer] # Invasion The aliens also found another primitive race they liked and gave them the same access the humans had. Unfortunately, the friendly aliens were duped by this other race. They not only had exceptionally good war tech, they had really effective ways to hide it from the good aliens. As such, the war aliens were able to use the network to invade multiple other locations before the good aliens realized what was going on. Earth got wind of it before they reached there, and as such, they destroyed the good aliens' link before they suffered the same fate. The good aliens promptly cut the war aliens off, but the damage was done. The war aliens conquered dozens of worlds before the cutoff and the good aliens don't want to go to war to fix or stop the war aliens. Earth now stands alone and fear keeps them from using the link technology, lest they let the war aliens in. The good aliens, realizing they screwed up, have quietly been feeding the humans bits of knowledge to develop their own technology (i.e. they told humans how some of their tech worked). Since humans now understand more about how things work, they set about building their own ships and making their own discoveries. [Answer] Humans don't have the equipment for field repairs of advanced alien technology. Imagine your ship is weeks away from a port, in hard vacuum, and not at a distance from the nearest star where it naturally maintains a liveable temperature. If the air or heat systems break right now, you will either fix them on your own or die. If the water recycler doesn't work, gosh, recycling it à la Bear Grylls isn't nice. If the engine won't start, you'll either die or have to hire a tug to come and decelerate you into port. If your critical systems run entirely on human technology, you know you can fix them with a screwdriver, a wrench, some duct tape and a laptop. If they're alien-human hybrid technology that writes its error logs in English and has RGB displays for control panels, you at least have a chance. If it's all alien technology with Centauri writing on V-UVa-UVb displays and you can't get at the wiring without a nano-disassembler, you're going to struggle. [Answer] Aliens are integral to the tech. They are not exactly ghosts... Hopefully not ghosts. But there is an intelligence of alien origin in each of these pieces of tech and it makes it go from the inside. These intelligences are related somehow to the aliens that provide the technology. The aliens acknowledge this if you get them drinking, but remain frustratingly vague or sometimes get religious (if very drunk). The mechanical parts of the alien machines can be duplicated precisely but the duplicates don't function like the original, if they function. The ghost in the machine is not itself a machine. It can be fickle. It might be fond of its owner or it might get royally pissed off. It has likes and dislikes. Under some circumstances the ghost in one machine might be moved to another; actually it might decide to move to another, or elsewhere entirely. Running these machines is more like dealing with a domesticated animal, if you have a domesticated animal more intelligent than you are. [Answer] Your question got me thinking of an answer that I have not seen yet, which we already do to each other as humans all the time. DRM (Digital rights management) or copy protection mechamisms The alien technology is mired in a complicated web of interplanetary intellectual property law that means the alien manufactured machines regularly have to phone home via some sort of hyperspace signal that humans cannot reverse engineer. The aliens have done this in order to have full control over the species they encounter as they intend for the inferior species to become dependant on their technologies and infrastructure. This is done as a security mechanism to assure their continued dominance in the galaxy. Humans, being human, do not like being reliant on the aliens and try to reverse engineer the technology with some (perhaps limited) success until they finally have their own flavor on the technologies themselves. Perhaps the aliens may resent this meteoric rise? [Answer] > > However, this created a problem for the setting of this long past, distant, future galaxy. If humans were given access to alien technology and spaceships which were so much better than humanity's best spaceships... > > > Those dumb humans only think they've got something cutting edge. It might be so much better than humanity's best, but to the "benevolent" aliens it is just so much old and out-of-date crap that none of their other trading partners would want such junk. Everything is fine for a while, until the humans piss off the neighbours, only to find their hand-me-down tech isn't quite so cutting edge as they thought, and they get their asses whupped. And to cap it all, when the humans ask for some upgrades, they are turned down. Now there's a reason to for the humans to get back to R&D, using some of the alien science, researching their own way, and developing their own tech - tech that they own and understand. [Answer] The aliens are awkwardly large, or small, or proportioned. Doesn't have to be by a lot; just enough to make alien tech as it's built uncomfortable, and for humans to be a small enough economic power that catering to them isn't useful. Also possible: Alien tech gives off radiation or leeches chemical compounds that are, on direct contact/very close proximity, less than beneficial to the health/comfort/longevity of humans. Doesn't mean it gives you lymphoma in three months and all bets are off; just means you need to build some shielding/adapt design to different materials/use different powersources with different cooling requirements/etc that necessitates a human flavor even on tech with imported concepts. [Answer] Aesthetics. > > There has to be a reasonable explanation for why humanity would keep developing technology that is decidedly different (and, until they can finally catch up to the aliens in terms of advancement, quite inferior) to the alien tech; otherwise after a while there would be little justification for why humanity's weapons, spaceships, and buildings would still look human and not just merge into alien looking things. > > > Even if the human technology were functionally identical to the alien tech, there would still be a perfectly good reason why it might look different--namely, humans think that human-looking tech looks nice! (Or cool, or comforting, or whatever.) Perhaps the alien tech looks strange, or awkward, or even kind of gross. Or maybe we just want to put out own personal brand on the things we build--after all, even within our own species, different cultures put their own unique spin on widely-used technologies all the time! [Answer] The alien technology has a fundamental, sometimes lethal, flaw. Sometimes these alien portals just disappear ships forever, or they blow up on arrival, or suffer extreme topological rearrangements through higher dimensions. Sometimes is rare, but significantly more frequent than the risk of using human craft that operate on other principles. Those other principles make these human ships much more limited in other ways. Range? Size? Speed? The aliens, (oddly? ), don't care about the flaw, or they stopped caring after finding it impossible to reduce it further. For whatever reason, they value self-preservation less than humans do. Perhaps they started as an eusocial species, and although they then emerged as true individuals, something we might call fatalism is very deeply built in to their psyches. We have made similar trade-offs between technologies at various points in our history. Early air travel was risky. Trains and ocean liners were by and large safer, and rail was cheaper, but ... slow! In this case, we could and did fix the safety problems with airliners. [Answer] ## This will be a gradual process From the beginning, we'll be building peripherals to make this alien tech easier to use. It may begin by just using human-built seats and control gadgetry for ergonomics and ease of training (making it similar to a battleship bridge or a fighter cockpit). Our scientists will be taking these apart when they can, though, and studying them to see if we can modify them or make them better. Eventually, we'll be reverse engineering the connecting systems, especially as those break and we don't want to go to the aliens and pay their (possibly) high prices to get new ones. We may never successfully (make native built versions economical) reverse engineer the core power systems or propulsion systems, but they may eventually be hidden behind so much value-added native human tech that few people know the difference. It's possible that the human ingenuity and can-do attitude even morphs into a reputation among other alien species for customizing foreign tech to their comfort levels. [Answer] Because the aliens make the humans EARN their tech Think of a school. Which teacher is more effective, the one that gives you the answers, or the one who teaches you how to find the answers? Yeah, I thought so. The aliens don't want the humans to become lazy and dependent upon their tech because that would drive them insane, much like how a teacher is driven insane by an ignorant child. So, instead, the aliens set up a video-game style "Path of Progression". Strategically placed signs with clearly understood diagrams or written cues tell humans what to do, and more strategically placed tech controls the direction of travel. If this sounds like a platform game, that's kind of what it is; not only are the aliens innate teachers, but they wax philosophical about the 'meaning of journies' and wouldn't dare take it from the humans. However, they would spy on them until they've selected their 'players,' stealthily knock them out with slow-acting tranquilizing gas, and then implant them with a Dopamine Drive that will make the humans feel sad or just plain wrong if they don't progress on the Path and happy if they do. Not only would they do that, but they will use these Dopamine Drives to 'guide' the players to pieces of alien tech, which they have to assemble in order to continue their adventure. For example, in a platform game, spring-loaded platforms allow someone to jump onto high-up structures. In this case, the poor human would have to build said platform themselves, put it in the right spot, and then jump on and stick the landing on the ledge above them. (Note: players may or may not die, and the aliens likely won't care because their death is because of idiocy/laziness/inability to keep a level head or follow simple instructions). That's not to say the aliens don't give the players choices; there are different variants of the Path, designed to engage the specific human. If he/she is fascinated by weapons, their Path will be more dangerous, but it will also come with the resources needed to fend off, escape, and even kill the monsters they'll encounter. If he/she has a 'need for speed,' they'll have to build vehicles to traverse different environments. If he/she has a drive to understand their world (and therefore the Paths), their Path will feature puzzles and increasingly advanced alien tech, eventually leading to an encounter with the aliens who made it. What happens to the latter group may be: 1. Returning home to educate their people 2. Being taken by the aliens 3. Being 'uplifted' by the addition of alien DNA (think Samus Aran, except engineering instead of combat-focused) 4. Being knocked out and taken to an island, which thanks to them and others like them will become this world's equivalent of Atlantis 5. They build a spaceship and blast off to explore the galaxy 6. They take the alien tech and use it to conquer the world, a la Alexander the Great 7. They become a mad scientist 8. The last engineering feat in their Path turns out to be a special chamber that modifies their DNA and infuses them with strange energy, turning them into a 'mage' I hope this helps, I sure enjoyed making this! [Answer] TL;DR: The supply part of Supply & Demand is unreliable. Long answer: I suggest you take a look at Larry Niven's Known Space novels\. Seriously, these deal with just the kind of problem you are facing. Within these novels, there are 4 main races; the humans, the Kzinti, the Gw'oth, the Outsiders, and the Pierson's Puppeteers. The humans and Kzinti are both relatively young, unadvanced races. The Puppeteers and the Outsiders, on the other hand, are incredibly old and wise. They generally keep to themselves (the Puppeteers are philosophical cowards, and the Outsiders have Old Geezer Syndrome), other than to trade their advanced technology (Outsiders) and indestructible hulls (Puppeteers). Although the alien technology becomes very prominent on Earth, it nevertheless does not take over the market. In the case of the Outsiders, they ask outrageous prices for their tech\. As for the Puppeteers, they abruptly leave after discovering a dire threat to themselves (the galactic core has gone supernova, so they \only\ have 20,000 years to leave before the radiation sterilizes everything). Due to these factors the supply of alien technology is massively variable, so the humans make their own. ]
[Question] [ This question already has answers here: [Can a planet survive a supernova?](/questions/19000/can-a-planet-survive-a-supernova) (5 answers) Closed 3 years ago. I am considering a scenario where people are anticipating the star of their system going supernova, which would be somehow triggered by an advanced, hostile alien race. However, the people cannot predict when it will happen. Their best option is to prepare some temporary shelter they can stay in until people from other systems can come extract them after the brunt of the explosion has passed. I considered them building bunkers deep underground that could shield them from radiation for a few days or weeks until help arrives. Is this a realistic way at all to temporarily protect yourself from your own star’s explosion? Or, would the planet heat up all the way through, making the underground unsafe? Or, would the planet just be completely destroyed? Taking into account planet size, distance from the star, size of the star, and radiation shielding technologies. In addition, as the supernova would be triggered by a hostile alien force, there is the possibility that its power may not be equal to that of a natural supernova. If not, any ideas for more realistic options of escape/defense in this situation? (Or some other stellar phenomenon that an underground bunker might be reasonable for?) [Answer] # No. A typical supernova will perhaps not destroy the planet, and "just" leave it as a burnt-out cinder. If that were all, then a refrigerated, shielded, very deep underground hideout could survive the onslaught. Indeed, such a hideout would survive the onslaught. But the supernova explosion will also lash out with a shock wave of neutrinos. While mostly harmless, neutrinos cannot be shielded by any ordinary matter, because their interaction probability is just too low. By the same token, a huge enough number of them will interact with matter; the whole planet will be flashed inside and out, and a significant portion of its constituent elements will undergo [inverse beta decay](https://en.wikipedia.org/wiki/Inverse_beta_decay). The necessary calculations are found [here](http://web.archive.org/web/20120313045458/http://www.andrewkaram.com/andy/pdf/HPJ.pdf) and yield a fluence of 8.4E+22 events per square meter at a distance of one parsec. Assuming a neutrino energy range of 5 to 15 MeV, the average dose at that distance would be between 1.4E-9 Sv and 1.6E-10 Sv. [Randall Munroe](https://what-if.xkcd.com/73/) derives an estimate of 0.5E-9 Sv, giving a LD at 2.3 AU; from the original figures, we can re-derive an absorbed LD (for a human-mass organism) between 1.3 and 4 AU depending on neutrino energy spectrum. While not too worrisome for mechanical systems and most electronics, that level of inverse beta decay is potentially lethal to anything organic. The only chance to avoid destruction is to escape - which will be a considerable endeavour, because you'll need to be at least [300 million kilometer distant to be barely out of the lethality envelope](https://physics.stackexchange.com/questions/440247/symptoms-of-lethal-neutrino-radiation-in-a-hypothetical-scenario). In all likelihood you will want to achieve a distance at least two orders of magnitude greater, which means completely escaping the doomed solar system. (This heavily relies on human absorbed doses. Even for humans, 5Sv is only a ballpark estimate of lethality; it is the single-exposure dose that kills 50% of exposed humans within one month. Even a 1Sv dose, which would happen at a distance of approximately 5 AU, has a death rate of around 5% for humans. On the other hand, [other organisms](https://en.wikipedia.org/wiki/Deinococcus_radiodurans) would probably tolerate it nicely). [Answer] A supernova is an hazardous object to be within in a radius of several light years because it's very, very, very energetic. To quote [Randall Munroe](https://what-if.xkcd.com/73/) > > his rule of thumb for estimating supernova-related numbers: However big you think supernovae are, they're bigger than that. > > > Here's a question to give you a sense of scale: > Which of the following would be brighter, in terms of the amount of energy delivered to your retina: > > > * A supernova, seen from as far away as the Sun is from the Earth, or > * The detonation of a hydrogen bomb pressed against your eyeball? > > > [![image of a hydrogen bomb pressed against your eyeball](https://i.stack.imgur.com/9Wgbo.png)](https://i.stack.imgur.com/9Wgbo.png) > > Applying the physicist rule of thumb suggests that the supernova is brighter. And indeed, it is ... by nine orders of magnitude. > > > The radiation shower following a supernova explosion is dangerous not only because it will exceed the tanning dose by several orders of magnitude, but also because it will strip the planet from its atmosphere and maybe even from a considerable amount of whatever it's below that atmosphere. Hiding underground to get shelter from a supernova looks like when Wile E Coyote opens an umbrella to get repair from the rocks about to drop on him. [Answer] This is an attempt to elaborate on L. Dutch’s answer with a simplified mathematical model and some calculations. To take a simplified view of a supernova, let’s assume that all of the [gravitational binding energy](https://en.wikipedia.org/wiki/Gravitational_binding_energy) of the star is converted into kinetic energy, radiation, etc during the blast. Assuming that the star has radius $R$, mass $M$, and uniform density $\delta=3M/4\pi R^3$, its gravitational binding energy is equal to $$\frac{3GM^2}{5R}$$ For our sun, this is about $2.3\cdot 10^{41}$ joules. Wow! Not all of this energy would be directed straight towards Earth. Let’s assume the supernova explodes symmetrically in all directions. Then, by the time this energy reaches Earth, it will be spread out over the surface of a sphere with radius equal to the distance between the Earth and the sun. The fraction of this energy that hits the Earth is approximately equal to $$\frac{\pi R\_E^2}{4\pi \text{AU}^2}\approx 4.5\cdot 10^{-10}$$ where $R\_E$ is the radius of the Earth and $\text{AU}$ is the Astronomical Unit (distance between the Earth and sun). Thus, the amount of energy received by the Earth is about $$(2.3\cdot 10^{41}\space\text{J})(4.5\cdot 10^{-10})\approx 1.04\cdot 10^{32}\space\text{J}$$ To estimate how much damage that would inflict, let’s calculate the binding energy of the Earth: $$\frac{3GM\_E^2}{5R\_E}\approx 2.24\cdot 10^{32}\space\text{J}$$ Surprisingly, that’s actually greater than the amount of supernova energy that would reach Earth! This means that the Earth wouldn’t be completely obliterated. However, as mentioned in L. Dutch’s answer, it would be very nearly obliterated. Although there wouldn’t be enough energy to completely disintegrate Earth, it would probably rip off the atmosphere and the upper layers of the Earth’s crust. It’s doubtful that your people would be able to dig deep enough underground to protect themselves. --- EDIT: According to @GaryWalker in the comments, my estimate for the energy output of a supernova is off by a factor of $1000$. So if there were any doubts before about whether a human bunker could survive, they can be safely dismissed. [Answer] Everybody isnthinking only about radiation. You probably did too, since you are considering whether people can shelter from it. When a star explodes as supernova it sheds mass. [From the Wikipedia article about supernova remnants:](https://en.wikipedia.org/wiki/Supernova_remnant) > > A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way. > > > (...) the resulting supernova explosion expels much or all of the stellar material with velocities as much as 10% the speed of light (or approximately 30,000 km/s). These speeds are highly supersonic, so a strong shock wave forms ahead of the ejecta. That heats the upstream plasma up to temperatures well above millions of K. The shock continuously slows down over time as it sweeps up the ambient medium, but it can expand over hundreds or thousands of years and over tens of parsecs before its speed falls below the local sound speed. > > > Even if you could shield yourself from the radiation in a planet (which you can't, as everybody else is showing you), the planet will be vaporized. The oncoming plasma that hits it will be millions of degrees hot in any scale, with each particle packing a hulk punch due to the immoral oncoming speed. And remember that supernova come from stars way more massive than the sun. The oncoming stream of stellar material will be more massive than any planet, so even if the planet could stay whole and solid after the initial blast it would still be surrounded by plasma hotter than a star; Hot enough to melt the planet. Just in case I haven't made myself clear enough, let's put this all in scale: * The [dino killing asteroid](https://en.wikipedia.org/wiki/Chicxulub_impactor) had a mass estimated around at most 4.6 × 1017 kg, with impact speed estimated at around 20 km/s. * For all we know, for the Moon to form [the Earth had to be hit by Theia](https://astronomy.stackexchange.com/a/28925/1042), with a mass of approximately 6.4 × 1023 kg, and an impact speed of around 4 km/s. This impact re-melted the crust of the Earth. By the way, the kinect energy input from this is five orders of magnitude greater than the dino killing one (i.e.: like 100,000 dino asteroids hitting at once). * To blow up as supernova, a star needs to have at least eight solar masses (so the exploding star will have at least ~1.6 × 1031 kg). And while the explosion is omnidirectional, potentially most of the mass will be blown across the star's plane of rotation (I believe clouds such as the [Veil Nebula](https://en.wikipedia.org/wiki/Veil_Nebula) provide evidence for this), which is where planet orbits will tend to be. We are therefore talking about multiple planetary masses coming onto your planet at 30,000 km/s. How many planetary masses will depend on your planet's size and distance from the star, with such data we might be able to calculate. But the mass and speeds involved don't bode well for anyone trying to escape the apocalypse in a vault. For a single Earth mass (already factoring in relativistic mass) in plasma hitting your planet at 10% the speed of light, the impact is nine orders of magnitude greater than the impact that created the Moon - or, in approximate terms, the same kinetic energy of a billion planets the size of Mars falling onto Earth. And that's still less energy than what you'll get in the form of gamma radiation from the supernova. [Answer] If the planet is Earth-like, e.g. it has a hot molten core, then you can't burrow very deeply without it getting too hot. That's why human's haven't managed to dig through the Earth's crust. The Kola Superdeep Borehole is 12,226 m deep and it's 180 C down there. [Answer] An issue as well is your "until help arrives" comment. It suggest you think someone could shield themselves from a supernova, but there exists a spaceship which could whitstand said supernova for long enough to evacuate a colony during the worst part of it. [according to this time line](https://www.universetoday.com/119733/how-quickly-does-a-supernova-happen/#:%7E:text=The%20outer%20edges%20of%20the,hours%20to%20reach%20the%20surface) you have hours, if that, until your solar system is screwed, and it will get worse over the next few weeks. If somehow you could withstand said supernova through all that by bunkering, you're not looking at a few weeks until help can arrive, but more likely a good few years. During which the surface of your planet will instantly go ozonless, then boil and liquify, then slowly freeze solid. Survival during that time with absolutely no access to natural biological resources will be enough trouble, but the inability to replenish your air makes this even worse. Practically, you'd need to build the equivalent of a space station underground close to the core of your planet. If you're going through all that effort, it would be much better to build an actual space ship and leave. And I mean leave now, because even as soon as you notice the start of a supernova, you're already too late to launch a space ship and escape. [Answer] Your basic problem from step one is 'anticipating' that a hostile Alien race 'cause' a Supernova to occur in the first place. That and the fact not every star is capable of becoming a supernova (aliens igniting it or not). Only the most massive stars can do it this. And there aren't many within reasonable range. It also implies contact with the race in question, so either we have traveled out into interstellar space and met them or they have traveled here. If its the latter case they literally don't need a supernova to kill us. By definition if they are that advanced (compared to us) and hostile we are DOA Supernova or not. A race with that kind of power would simply not have to bother with Supernova to deal with a species that wasn't at least near their (God Like) tech level. That leaves us meeting them out there. And if that the case we have not only have advance warning we have also probably spread out in the opposite stellar direction anyway. So taking out Earth, while a tremendous blow doesn't kill off all the annoying apes anyway - we're still out there in the stars somewhere. In terms of the effect on Earth. Bunkers would protect humanity and any species we selected from the worst effects of a Supernova which primarily involve the destruction of the ozone layer. Humanity could remain underground for a few decades/generations until the worst effects have past. So if the aliens are intending to kill us all off they have gone to an awful lot of effort for very little effect. A better scenario would be a simper one. Human astronomers a few years from now (pick your date) start to detect preliminary changes in local large star (there is a list of candidates) that indicates it has or will go Supernova shortly. Of course Einstein gets in the way (AGAIN) as it could have gone BOOM already and we wouldn't know sans early signs until the first signs/wave front arrived. Giving humanity a precise period of time to prepare based on how many light years the chosen star is away and what advance warning (changes in the star) there are. [Answer] Of course it's possible. With the right assumptions just about anything is possible. Assume: the planet is massive, but has a cold core and is made of something rigid, so it doesn't flow like a liquid under its own weight. And it's far from the exploding sun. And the race living on it has advanced technology with access to vast amount of unobtanium, which reflects neutrinos, doesn't conduct heat well, and is entirely shatterproof. Then they tunnel to the core, build their shelter from unobtanium, install their hyperfusion reactors, load up on food sources, pile in and close the hatch. Dimly, they hear a boom, and then they just wait, because the environment outside their shelter isn't going to be healthy for quite some time. Occasionally they burp out any waste heat so they don't cook themselves. Time passes. Eventually they open the hatch. What do they find? You're the author, so you get to decide, but it's reasonable to assume there's no planet left there anymore, or at least nothing that can support what we usually think of as life. So they'd do best to rig their reactor to generate propulsion and move their habitat to some other star. Volia, they (well, probably their descendants if they aren't immortal) survived. If they have all that tech, though, they could drive off the attacking aliens with unobtanium bullets and green death-star rays and keep their planet safe that way. Realistic? Of course not. But you posited aliens that can make a sun go supernova so you're already off the map, in terms of realism. There are a lot of simpler, entirely feasible ways of taking out life on a planet, if that's the goal. A large number of messy nuclear bombs will likely do it. Why get all high tech? ]
[Question] [ I love my Death Star. There is nothing more thrilling than pulverizing a planet and feeling the inhabitants screaming out in terror. However, my Death Star seems to have developed a case of [Kessler Syndrome](https://en.wikipedia.org/wiki/Kessler_syndrome). Fragments of the planets, moons, and ships that we have destroyed get pulled into orbit around our space station. They crash into each other, breaking up into smaller pieces, and forming a debris field. This has caused problems with our fully armed and operational battlestation. Wreckage has damaged portions of the base's superstructure. Several TIE fighters sent out on patrol have been lost by collisions with debris. And every time a dignitary visits on a shuttlecraft, I cross my bionic fingers that they arrive and depart safely. I am so frustrated that I feel like strangling an admiral. What can be done to rid my moon-sized fortress of this pitiful problem? [![Kessler Syndrome](https://i.stack.imgur.com/bBZmP.jpg)](https://i.stack.imgur.com/bBZmP.jpg) --- > > There are a large number of queries regarding the Kessler Syndrome. While this one's clever, does it really ask anything substantially different from several of the other "how do I deal with junk clouds around a space body" questions? – elemtilas > > > The certainly are a few other ([1](https://worldbuilding.stackexchange.com/q/58587/52704),[2](https://worldbuilding.stackexchange.com/q/63923/52704)) questions on the [kessler-syndrome](/questions/tagged/kessler-syndrome "show questions tagged 'kessler-syndrome'") topic. Those questions ask for [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") answers, or answers that are realistic in our world. Those existing questions reject answers based in science fiction. This means that there would be no place anywhere for answers based on tractor beams, shield generators, or other sci-fi technologies. Most of the answers already submitted to this question would have no place, anywhere. That's why this question is necessary. I totally understand the concern about opening up an endless variety of similar questions. There's little to be gained by having a different question for each sci-fi franchise. The Star Wars universe is rich enough that most concepts found in other franchises have a solution in its universe as well. In other words, had the question been already posted in the context of Star Trek, then this question would have been a duplicate of that, as the answers would be substantially the same. Therefore, one question for sci-fi based answers is sufficient. [Answer] Your Death Star has a hyperdrive, right? Well, the debris doesn't. Even if it maneuvers just at sublight speed, debris won't settle into orbit. If there is a debris problem, it is being hit by fragments, not being orbited by fragments. You'd probably want to avoid that. If we think back to TESB, the Star Destroyer [Avenger](https://starwars.fandom.com/wiki/Avenger) dumped trash which was presumably not taken along into FTL. So debris in close proximity but not in contact with the Death Star will not be taken along, either. [Answer] # Capitalism Sell salvage rights to the worlds you don't destroy. They'll pay you for the privilege. Most of the exploded planet bits will not stick around in your orbit as you move from star system to star system. There will still be a fair amount of debris, so salvage won't get rid of all of it. But it will make a sizable dent. Enough to greatly reduce damage to your shuttles and other craft, as well as to your Death Star's systems. Every year or so, make a stop at Al's Pancake House and Super Salvage World. Give your crew a much needed vacation and let Al's equipment attract all that debris away from you. Leave lighter and freer and ready to take on new challenges in planet busting. [Answer] Do you not have a giant death ray at your disposal? Dial it down a notch and use it to gently push the debris away, or dial it up and turn the debris near you into an ionised gas you can then siphon into your very scientifically rigorous plasma conduits. Either way: bye bye debris! [Answer] This cannot actually happen. To get the Kessler syndrome you need to start with objects in orbit which then collide with each other in a cascade. None of the planets or moons you destroyed was in orbit around the Death Star, thus the debris cannot cause a Kessler effect. Now you can argue that the amount of debris generated is simply so large that some of the debris ended up in colliding with other debris in a way that caused it to end up in orbit around the Death Star. And, why not. Planets capture moons, star capture planets. Why could the Death Star not capture some debris? Well, that is because the Death Star is mobile. It has sub-light drives that can accelerate it. There are no stable orbits around it that anything could be captured to. Hence debris orbiting it cannot accumulate and cannot cause Kessler syndrome. And, as others have mentioned, it is unlikely that any debris in orbit would survive going to hyperspace. Or approaching a planetary body under power. Or firing that "super-laser". It puts out lots of power and would give any nearby debris a good shove. And, if we are talking about Star Wars Death Star, much of its gravity field is a side effect of its power plants and drives, meaning that its gravity field would almost certainly fluctuate when firing the gun. [Answer] Well assuming its just like in Star Wars, you have the technology to control gravity. Just turn it off for a few hours, maybe a day, and all the debris will naturally move away under its own inertia. [Answer] ## Do a fly-by near a planet (preferably with atmosphere). You might think that your Death Star is huge, but actually that is just because it is yours. When compared to most planets, your Death Star is small and, more importantly, light1. Just go near enough of a big orbital body and let that body gravity's do the work. There may be some inconveniences by part of the debris landing on your Death Star (instead of on the cleaning body), but if that was much of an issue your Death Star would already suffered a lot from the impacts when the Kessler body was created. Additionally, if your selected celestial body has an atmosphere, the upper layers of it, while thin, can still help to slow the Kessler objects and make them fall from orbit (in either direction) faster. --- 1Ok, actually with a small mass would be a better term, as an object in space will have zero weight. [Answer] # Let your enemy fix the problem for you. Your Death Star seems to be suffering from excessive orbital debris. No problem! There is an obvious solution to this issue that no one else has suggested. (As an added bonus, this is a tried and true method.) All you need to do is intentionally include some glaring weaknesses in your Death Star design. Once you start to notice the orbital debris becoming an issue, make sure that detailed plans of your superweapon platform somehow get into enemy hands. Then, simply wait for some rebels to come and blow up your problem for you. They will think they have won a great victory, but in reality they will have merely sacrificed dozens of their own ships to help you fulfill your master plan. With the old debris-ridden battlesation out of the way, you can rebuild your Death Star yet again. Not only can you rebuild this version with those all-leather interiors that you've always wanted, but more importantly there will be no giant debris field orbiting your newly constructed battlestation. Problem solved! TL;DR Just nuke it and build a new one whenever the debris becomes a problem. [Answer] Use your tried and true tractor beam. You don’t need to acknowledge that you have one, just nod imperceptibly... We all know that you must have such weapons to bring in any smuggler ships that happen to fly by your station. So just trap and collect all debris, and when it is in a manageable launch bay, you can collect the metal and recycle other materials in one of your garbage compactors; you have those too, don’t you? (just nod...) [Answer] Lasers and Controlled Explosions By using lasers and explosive to break the debris into smaller pieces, it significantly reduces the damage they could cause due to the reduced mass. You may also be able to mine any resources you find in the debris. A series of controlled explosions may be able to move some of the larger debris away from the station rather than trying to completely destroy it. A further possibility is to use a ship like a plow or using a net. You would fly the ship near the debris, catch it with either the plow or net and push it further into space, away from your station. If using lasers though, just be careful not to end up like Peragus II [![enter image description here](https://i.stack.imgur.com/QB7oP.jpg)](https://i.stack.imgur.com/QB7oP.jpg) [![enter image description here](https://i.stack.imgur.com/gB0aI.jpg)](https://i.stack.imgur.com/gB0aI.jpg) <https://lparchive.org/Knights-of-the-Old-Republic-II/Update%206/> Perhaps using droids equipped with lasers to mine the debris would be a far safer alternative, reducing the risk to human lives. [![enter image description here](https://i.stack.imgur.com/9RTGa.jpg)](https://i.stack.imgur.com/9RTGa.jpg) <https://biobreak.wordpress.com/2017/04/20/kotor-2-peragus/> Then again, maybe its not such a good idea... [Answer] Its part of the defense grid The death star is huge, it has a lot of mass that gives it some gravitic muscle. But the death star moves, so the only reason it is maintained at all is because those huge generators and advanced gravity generators are doing their job. That is maintaining a near field anti-fighter, anti-missile, anti-torpedo, and ablative defense grid. Of course the technology is still being perfected, its only the third death star and we really do not want surprise fighters, or another Millennium Falcon getting close again. Small Debris, and Openings The problem is of course the small debris that don't respond readily to gravitic intervention on account of being fast, and so mass free. The other problem is opening a large enough hole in the defense grid to permit bombardment by the primary weapon, or a hyper-jump. Negative Gravitic Pressure The first measure would be to create a negative gravitic pressure. This would push mass away from the battle station that comes too close. This would encourage debris to orbit further away from our glorious weapons platform. This should handle the slower moving debris and keep the more massive objects in line. As a perk it also acts as a counter measure to incoming spacecraft slowing them down to allow a weapons lock. Lasers Weapons lock is useful not just against fighters, but those medium to small objects that can be ablated by our turbo turrets. This would create a lovely ionised plasma encircling the star adding to the woes of any approaching starcraft. Magnets With our advanced control of magnetic fields the newly ionised material can be maintained in a similar way to the mass based objects further out. As an extra benefit some (or all of it) can be conducted to polar collection stations to supply materials for our on board nano-lathes and micro-factories. This could even be done intentionally when resources are low on board... Shields, and Armour While expensive, our Death Moon has had no expense spared (except for all of these manually aimed and fired cannons). So our deflector screens and shields are top of the range. While not strictly necessary our Armour is heavily invested in too. Fortunately due to all of those evaporated planets many tonnes of dura-steel has been extracted and used to reinforce the armour on the station (at next to no cost). Which is being constantly repaired by heroically programmed repair droids (with a lack of self preservation reflex). Similarly built from the debris of earlier destroyed planets. AI, and Control Software The only thing we are missing is an automated tracking, control and response grid to maintain this debris shield. All of the accidents that have recently occurred were due to human error, and no wonder the infirmary is packed with strangled operators. They simply are not up to the challenge. Our recommendation is to introduce automation and retrain all of those cannon controllers, array engineers, and various support personnel as Storm Troopers, or at least Fodder Troopers. Storm Troopers take a lot of training and need to be used strategically. As an upshot any visiting dignitary that does not make it through the defense screen is either too stupid (human error), or a gleaming example of the effectiveness of the defense system. So keep a few human operators around to throttle as required. Firing and Navigation Of course aiming our primary weapon is a little more difficult with all of that debris in the way. Fortunately our scientists developed the beam to go through several thousand kilometers of solid rock. They believe that the debris will only reduce the effectiveness of the weapon by about 0.5%. As an interesting side effect our scientists believe that they can defocus the main gun to clear a large swath of nearby targets. Which will allow us to evaporate much of the nearby debris allowing a safe hyper-space jump. [Answer] Simple: your Death Star does not suffer from Kessler syndrome If you accept that Kessler syndrome applies to your universe, then your universe obeys mostly to law of physics of this universe, too. Which means in your universe space is very big and mostly empty, that planet are held together by a strong gravity, and they are orbiting a star. So what? Well: * A planet doesn't explode by puffing smoke and some debris for a few kilometer: the power of the explosion will spread pieces of it at extreme speed all over the planetary system and beyond. * Practically all the material will explode in the direction the planet was orbiting (inertia). A civilization advanced enough to build a Death Star doesn't willingly put itself in the path of the explosion. * Such advanced civilization will destroy a planet with an angle such that the debris will follow a predetermined path anyway. Shooting the planet from slightly behind and outward from his orbit, a bit after the aphelion, so that the fragments will get a falling orbit toward the sun, if there are not inhabitated planet in the system to worry about. Or it will shoot standing between the star and the planet at either the perihelion or aphelion, depending on which direction is safer. * Anyway, space is big, so your Death star will be reached by just a bunch of debris. Even if they decide to stand right in their path. * Unless you decided to explode the planet by standing just in front of it at very close distance. In that case your ship will be reached by a lot of material travelling at extreme high speed, high enough to completely ignore the gravity pull of your tiny moon. * Or, in short: if you are in the path of lot of material, it will move too fast to care about you. If the material will be slow enough to get caught in your orbit, it will be a stone. Maybe two. * In any case, if you are putting yourself in the path of the explosion, it means you have enough shields to withstand being invested by all the stuff coming out of it. Just push the pedal to the metal and move away, and the two or three rocks will bounce away on your shields and get left behind. [Answer] Oh, for heaven's sake! USE THE DARK SIDE!!!! Channel your anger into a towering baseball bat of rage, and smash those offending bits of space junk away from the Death Star! And...while you're at it...y'know...you might just *accidentally-like* smash a particularly annoying bit of orbital gunk right at the Emperor's command tower. For as a Sith Lord you always: 1. Remember the Rule of Two, 2. Serve your master with slavish devotion, until 3. You kill him and take his place!!! :-) [Answer] An alternative could be to reverse the polarity on the tractor beam, thereby creating a repulsor beam effect. Then tie the repulsor into the shield generators, creating a station wide repulsion shield. Anything currently in close proximity, or indeed anything entering with a thousand kilometers of the station's shield would be deflected away, at speed. Main point is to remember to add an opening for landing craft... Otherwise it could get messy! ]
[Question] [ > > THIS IS A TEST of the Galactic Emergency Alert system > > > No action is required. > > > Type: Milkyway Empire > > > # The World In the near future: * we discover FTL * we run into some friendly aliens that are part of a benevolent galactic "empire" * in order to join, we must have a global emergency alert system that can reach >95% of our population Most areas can be covered by cell phone/tv/radio alerts. It is getting the alert out to the remote areas that concerns me "remote areas" * Areas without cell service and no other alert method (radio,etc) * Areas with a warning system that we can't automate/hook into * Areas without a warning system at all (and no radio/etc.) * Areas without electricity # Partial Solution I believe we can mass produce a simple pole with * antennae * Raspberry Pi * solar panels * batteries * loudspeakers I can see deploying these in remote areas via B-52. The pole is dropped, it will jam itself into the ground and activate (pole is designed to manage terminal velocity) # Question Including manufacturing time, how long would it take to ensure that >95% of the population would hear the global alert? Assume that all major countries want to contribute.(The empire has a LOT of benefits when we join) [Answer] # Reduce the Population 95% gets a lot easier if you can chop off the long tail. Now that you can move things faster than the speed of light, kinetic kill weapons can devestate the world. While world leaders debate how to achieve the goal, a rogue faction secedes to the moon, cracks the earth in half, and neatly qualifies for entry into the galactic fold. Then, they emigrate somewhere nicer than this galactic backwater. [Answer] First off, >95% coverage means that, with a worldwide population of 7 billion, you can ignore 350 million people. Which I feel like gives you some wiggle room. Second, when you say 'near future,' what do you mean? If you mean anything longer than the next few years, you may not need to do anything other than use cell phones. As of 2017, about [70% of the world's population](https://venturebeat.com/2017/06/13/5-billion-people-now-have-a-mobile-phone-connection-according-to-gsma-data/) owned one, and that percentage is rapidly increasing. In many areas of the world, mobile phones are the way you access the internet. Additionally, about a [quarter of the world's population is under 14 years old](https://data.worldbank.org/indicator/sp.pop.0014.to.zs). The vast majority of these children, I believe it's safe to say, will be within hearing distance of an adult. So, 70% of the world has cell phones. 25% are close enough to an adult to hear one in an emergency. Adding those together gives you 95% coverage. Now, that's cutting it a little close as of 2017, but with the increasing ubiquity of mobile devices, I don't think it's unreasonable to assume in your 'near future' scenario that more than 95% could hear a cell phone if it went off. But what if you wanted to be even more sure? Well, as we're all aware, humans are not evenly distributed across the planet. China and India each have more than a billion people, and many of those are among the poorest in the world... and they also live in large cities. By hooking up your raspberry pi to some airhorns in those large cities, you can pick up whole percentage points of the world population. Want to be even more sure? Require phone manufacturers to donate a few tens of millions of devices, for the good of the planet. Ship those devices to every village in Africa and rural community in India, and voila! Even better coverage. So, even assuming you're not happy with the current growth of cell phone usage worldwide, which within the next few years will easily take you over 95% coverage, manufacturing and shipping those cheap mobile devices for rural areas would take, what, a year? At most? We're already making hundreds of millions of phones now, so it wouldn't take long to redirect them where they're needed if necessary. [Answer] Detonating nukes in very high altitudes causes a lot of noise and [brings along some nice pyrotechnical effects](https://en.m.wikipedia.org/wiki/High-altitude_nuclear_explosion): > > In general, nuclear effects in space (or very high altitudes) have a qualitatively different display. While an atmospheric nuclear explosion has a characteristic mushroom-shaped cloud, high-altitude and space explosions tend to manifest a spherical 'cloud,' reminiscent of other space-based explosions until distorted by Earth's magnetic field, and the charged particles resulting from the blast can cross hemispheres to create an auroral display which has led documentary maker Peter Kuran to characterize these detonations as 'the rainbow bombs'. > > > If we have the tech for FTL, we have the tech to blow some nuclear fireworks up high. That should gather a lot of attention. We could do it around the globe. [Answer] Is the scope of the system to only be on Earth? If that is the case, then satellites should suffice, as we have had 100% coverage for decades now. The old Iridium constellation, famous for its satellite flares, was able to completely cover the Earth, as shown below: [![enter image description here](https://i.stack.imgur.com/LD0v2.gif)](https://i.stack.imgur.com/LD0v2.gif) Simply use a satellite alert system for phones, or use those pole thingies you mentioned but hook them up to a satellite. [Answer] # [Low Frequency Radio](https://www.nist.gov/pml/time-and-frequency-division/radio-stations/wwvb/help-wwvb-radio-controlled-clocks) Remember those radio-controlled clocks? They get the current time from a radio signal. The entire United States is covered by one broadcast tower in Fort Collins, Colorado. It operates on 60 kHz band. This tower broadcasts at 1 bit per second, but you could presumably increase the baud rate a bit... What you would do is give every citizen a little device that would listen for this broadcast. This antenna could also be placed in cell phones, clocks (duh), and other devices. So for the technophobes that don't want phones or whatever you could use that arduino setup you mentioned, deploying them in strategic areas, instead of all over the world. As for the broadcast towers, to build in redundancy, I'd go with two per continent. As for the message, unless you want to ignore the 1 bit per second part, it could just say "get to a tv/radio/Internet access point!" [Answer] Induced Gravitational Harmonics You didn't mention if you have artificial gravity to go with your FTL or not, but if you do, and depending on how it works, inducing fluctuations in the planet's natural gravity at a frequency audible to humans could make every loose object on the entire planet vibrate out your message all at once. As a bonus, more targeted manipulation could be used to crush flat anyone who doesn't want to join the galactic empire. Solar Thermal Transducer If you don't have sufficient artificial gravity power to pull this off, set up a solar laser array. Pumping a few gigawats of thermal energy into the atmosphere at the proper frequency and dispersement pattern should let you create arbitrarily loud sounds at arbitrary points on the planet's surface. You'd just have to keep your message short to avoid, shall we say, unpleasant side-effects... As a bonus, any dissidents who don't want to join the galactic empire can simply be vaporized in the middle of the night. No muss, no fuss, no witnesses! Radio There is a school near where I live that is less than a mile from a 50,000 watt radio transmitter station. As it turns out, you'd be amazed what kinds of things can be used as AM receivers if the signal is strong enough... Lockers, desks, telephone lines, people's fillings... Anything conductive and capable of vibrating is potentially susceptible to being driven by a sufficiently powerful signal. The energy budget to blanket the globe this way is probably cost-prohibitive given that you'd have to convert it to radio waves, and the damage it might do to sensitive electronics would also be expensive, so the other options are likely better. [Answer] What about projecting the message on the moon? Everybody can see it, you only need one powerful enough projector rather than a global installation, you can cover the costs through ads. The problem however would be language and the fact that the message would not be instantanious for everybody. Or instead of projecting on the moon, set up a (or multiple) sufficiently large screen(s) in higher orbit and project on those. [Answer] Regarding the viability of purchasing a phone for every person in the world: <https://www.nbim.no/no/> - 8 468 829 792 352 nok (about a trillion dollars) That is the savings of Norway, a small european country of 5 million people. That is more than enough to buy a smartphone for the last 30% of the world who are still disconnected from the internet. I am sure we could figure something out. [Answer] This would be trivial with today's technology because, # Fortunately in our real world there's a near-duopoly on device OS. Couldn't be easier. In five minutes the 2 major device OS, and the few minor device OS, could be forced to add more "emergency alert" functions than they do now. Step 2, governments would simply mandate that older versions of the OS don't work, which is easy to achieve. None of that is any harder then, say, that you "must have brakes on a vehicle" and so on - any regulation. A tiny number of people don't have a device currently; it would only cost a few billion to make a minimal one for those folks. Note that a few nutters would want to avoid being contacted: your 95% rule easily covers that case. Easy! *Thanks to the current duopoly on device operating systems.* [Answer] There seems to be two assumptions that people are making that I want to unpick: 1. That a warning signal must be in a spoken language. 2. That "urgency" means getting the message to people in minutes rather than days. Put a set of nuclear-powered satellites in low-earth orbit, such that their orbits cover the globe. Fit each with an incredibly a bright light source - perhaps an array of thousands and thousands of LEDs? Take the time to contact the hard-to-reach population areas the slow way - by mail or in person - and tell them where to look in the sky each night for the signal. Give them training on what action they should take if they see the emergency light. ]
[Question] [ Say we have a large cargo spaceship and a small pirate spaceship. The pirate ship is the only one with any sort of weaponry (lasers, missiles etc.), but for the pirates to safely retrieve the cargo, they decide to board the ship and take it manually since teleportation is impossible. So, how could a pirate board the cargo ship, without letting the precious cargo fly off into space, if a gaping hole in the side of the cargo bay would certainly mean the cargo would get ejected into space? [Answer] One way would be to use suction pads. The problem is that suction pads use air pressure in order to work, so they do not work in a vacuum. That means that you cannot attach a suction pad on the outside of a spaceship. However you can attach it inside, in order to create an airlock. Here is how it would work: * Before creating an airlock, you need to be firmly attached to the ship. That can be made thanks to a sort of harpoon. Once the harpoon has gone through the hull of the big ship, it opens up and liberates a plastic circle, which mill make your suction pad. What happens is that when the air inside the ship will try to escape, it will actually push the membrane, so that it will cover the hole. Then the difference of pressure between the air inside the ship and the void outside will keep the membrane in place. * With enough harpoons, you can get a good grip on the big ship. Now to create the air-lock. It is the same principle. You project a big tube towards the hull of the big ship. Once you are through, you deploy membranes that will prevent the air from escaping. Edit: The basic shape of the harpoons would be something close to umbrellas, which would open once inside the ship. The "inside" of the umbrella would at pressure zero thanks to the hole you just made, and the "outside" would be at room pressure. The ribs can also help to reinforce the harpoon, much as the barbs of real-life harpoons. Concerning the air lock, the things you deploy have something like a corona-shape. Two more things I did not mention: * The defending ship has no interest in breaking your harpoons since that would result in the depressurization of their ship. * A good way to prevent the suction pads from working would be to depressurize the defending ship. However your harpoons would still work, just like regular harpoons. [Answer] The canonical solution in scifi is as mentioned by others threaten to open fire unless the ship allows you to board. This is not only practical (unless you have a reputation for killing surrendered crews), but low risk. It is also financially efficient as it keeps the ship and cargo value intact and the crew alive for ransom. It is also generally best solution for the owner as it only causes losses that can be covered by insurance. And paying insurance is generally cheaper than arming the ship so it can defend itself and paying the crew for fighting. Exception is if the pirates have a reputation for killing crews or the piracy is actually part of some sort of an ongoing larger conflict. But that is rare as pirates generally hate fighting, there is no profit. Everything you spend on fighting reduces profit and increases risk. So most pirates try to keep surrender the best option by not killing surrendered people unless necessary. Incompetence and stupidity does exist though. As do insane people and religious fanatics. In addition to being common in scifi this is how most real pirates have operated. Fighting is only done until one side thinks fighting is more dangerous than giving up. Usually which side is stronger gets obvious without unnecessary bloodshed. [Answer] Your question already assumes that the cargo ship is weaponless, and we'll also assume for the sake of simplicity that the pirates have already taken care of any escorts that might be around, so they aren't in any danger of getting blown out of the figurative water. The problem now is - they need to get the precious cargo off the cargo ship. For that, I see three possible ways to enter the ship: --- Boarding Through Airlocks The most obvious way is to simply slip spacesuits on and pop open an airlock from the outside. Any space-faring vessel should have some type of de-pressurizing zone the pirates can use to their advantage to access and enter the ship. Depending on your priates' style, this can be done either after they've done precision damage to render the ship immobile, or mid-flight and stealthily to avoid any detection whatsoever. --- Make-Your-Own-Airlock If for some reason the ship doesn't have an entryway, they could make one on their own. Simply give your pirates an attachment to the ship that manually digs into the hull, preferably 'locking-on' like a claw, that allows the pirates to connect one ship to another for easy boarding. It doesn't matter if they then leave a huge hole in the ship's hull after they leave - they're pirates. They got the cargo. Let the poor saps with a hole in their ship worry about that. --- Just Use The Vacuum The pirates are trying to get the cargo out of the cargo carrier. For them, letting the vacuum of space do the work for them. From there, it's just a matter of snatching the cargo out of space - either by hand with space suits, or just by flying by and scooping it into the ship through a de-pressurized 'mouth' piece, ideal for taking cargo out of the motionless vacuum of space. (Or Tractor Beams, if you want to have those). [Answer] ## [Space Harpoons](https://xkcd.com/1402/)! And gamma-ray lasers. Match speed and course. Aim. Fire all starboard harpoons! Okay, maybe harpoons are bad idea... but they sure are cool so mount them anyway. Everything depends on cargo ship design. Cargo spaceship will consists of three main parts: * main engine * crew compartment * cargo hold For commercial scale transit cargo hold would be big enough to make it main hull, while engines and crew compartment would be just an attachment on top of it. In pair with it comes space elevator and/or surface-orbit cargo shuttles. Launching single monstrosity between planets would be cheaper but in same time making in unable to perform planetary landing and having low thrust-to-mass ratio. Even entering parking orbit would be waste of money (both fuel and time equals money), so instead they would just come close enough for rendezvous with local high thrust-to-mass (which implies short range) haulers. In space you do not even need to dock, just drop cargo container with radio beacon for locals to detect and pick up while cargo ship uses its own hauler/tractor beams to pick up new containers. So now we have giant cargo ship plowing slowly but without stop through space as parking this behemoth would just cost too much. As it is capable of transferring cargo containers in-flight all you need is to convince its crew to push a button, automatic storage of fixed-size containers is quite easy (when compared to space ships) in 0g environment. Or you can just convince their computers. And here where gamma-ray lasers come in handy. Talking is bothersome, lasers are accurate. 1. Approach cargo ship with cool looking pirate ships, with harpoons, skulls and cannons. Intimidation is useful. Maintain radio silence. 2. Point graser at crew compartment. Engage at low power, just enough to make bridge glow with yellow warning lights. Suggest ship crew that sharing cargo list would be wise choice. 3. Select interesting cargo, remember that your pirate ship must be fast which induces low cargo capacity. Gently ask sailors to release selected containers in space. Gently increase graser power so cargo ship bridge lights will turn red. 4. Collect your loot and leave cargo ship alone, thank its sailors for cooperation. Destroying more than you can carry is counter productive, after all you want to loot this ship with same crew another year, training newbies in business is such a pain. So what if cargo ship refuses to comply? 1. Slowly (space is big, you have time) turn your graser up [11](https://xkcd.com/670/). Remember to aim only at crew compartment. 2. Fire magnetic harpoon. 3. Wait for newly elected captain to send apologies for his unwise predecessor and proceed with previous checklist. In case sailors are suicidal: 1. Disable graser after it did its job. 2. Send your engineers to cargo ships (harpoons tend to have line attached to them, it helps with ship-to-ship transfer). 3. Starts transferring cargo on your own. 4. Leave peacefully, do not damage cargo or ships more than you need to, if it can be salvaged it will be sent again... for you to loot! It would create certain culture of piracy: * Do not steal military cargo, military tend to have fast and heavily armed ships. * Do not steal critical cargo for colonies/stations, stealing critical supplies could lead to indirect genocide. Remember that you do not want to meet military ships. * If any moron breaks those rules, take care of him before military ships come knocking on your Tortuga. Some military captain gets easy promotion, your favorite brothel is not nuked from orbit. [Answer] Currently most spaceships are expected to be made from metal. Most likely one that has magnetic properties (at least enough for this purpose). Large electromagnets on cables can attach the pirate ship, and then it can have a tube with another electromagnet that is big enough to cut an entry port with, like a lamprey eel. The smaller cables could have smaller versions that could poke weapons through the hull to protect the door that is cut through the hull for the boarders. They can promise that if there is no funny business, they will take what they want and leave, closing the holes behind them else... [Answer] I'd like to suggest something different. Given the huge success of shipping containers here on Earth in the last 50 years ([http://www.amazon.com/The-Box-Shipping-Container-Smaller/dp/0691136408](http://rads.stackoverflow.com/amzn/click/0691136408)) I would suggest that a similar cargo handing system would also be more efficient for space travel. Moreover, as at least one of the other answers suggested regarding the cargo hold, each container would be individually powered, warmed, pressurised as required by it's contents. On a large cargo vessel in space, moving the containers in and out would be an unnecessary waste of time and effort. Instead they could be attached externally to the ship, only requiring the connection of an umbilical for power, air etc as mentioned above, and sufficient clamping/bracing to cope with the expected acceleration/deceleration of the trip. So, I would expect some sort of modular racking system external to the ship's hull. Given this situation, pirates would only have to draw near, and send over ROVs to detach and eject the containers, which the pirate ship could then collect. The ROVs could perhaps be adapted versions of the robots used to load/unload the cargo at space ports. Or, if it suits your story better, a giant articulated arm on the pirate ship could detach containers and move them over to attach them to the pirate ship. Or the cargo vessel's computers are hacked to order the release of the containers. Another angle could be that the containers are stripped off the vessel, to be collected later by the pirates. [Answer] I would personally favour a boarding pod. Essentially, you fill a torpedo-like pod with your finest pirates and fire it at the cargo ship. When the torpedo smashes into the side of the cargo ship, the impact activates expanding foam (like the polyurethane foams available to us right now) around the exterior of the boarding pod which seals the breach, while armoured pirates burst out of the doors at the front of the pod. Either the crew surrenders, or is gunned down, leaving the pirates to bring it back to space-Tortuga or drop the desired cargo into their primary vessel by whatever means they see fit to employ. If the pirates miss, they can waste the cargo ship and collect the boarding pod for the next attack. This has the benefit of being (aside from the assumptions of casual space flight) completely within our current technological reach. [Answer] Assumptions * Precious cargo equal livestocks, a dead corpse or carcass equal game over for pirate. * Both vessels are manned. * Pirates don't negotiate. * Cargo ship cannot out run pirates. * Cargo ship is defenseless. * Both vessels are close to a black hole. Learn from the pro! * fire emp KO all vessels including pirates. * soon both ship will be pulled by the black hole. * send another merchant ship(stolen much earlier and manned by pirates) to the rescue. * Merchant ship will use tracker beam to pull the cargo ship away from black hole. * Prepare the crew from the cargo ship to come out and board the merchant ship. * Cargo ship is now unmanned and ready for the taking. [Answer] Similar to Ville Niemi's answer, but more detail on actual combat. Demand the vessel surrender. If they do, board through whatever air-locks the ship uses while in port. This should be fairly standard, as air-locks are required everywhere. If they resist, open fire. Use a weapon designed to penetrate, not explode (ie, something high density, high velocity). Aim for the engineering spaces, based either on known ship layout, or thermal imaging - power plants give off heat. This should result in a minimum amount of structural damage, and a maximum amount of on-board casualties. Contrary to what TV and movies would have you think, it's pretty difficult to make things explode. It is easy to make them break. Damaging the engineering spaces is likely to release super-heated steam, high pressure hydraulic-oil, and potentially radiation, killing many of the crew members in that area. It will also shut off the source of electrical power. Without power, there will be no atmosphere control or temperature control. Over the next few hours, the remaining crew will die of CO2 poisoning, hypothermia, etc. Space suits will only provide a few more hours of heat and oxygen. Wait as long as you can afford - days if the ship is far from potential assistance - and then board via the standard airlock. It's likely that after a few of these encounters unarmed ships will simply surrender when the demand is given. They may also begin arming themselves and traveling in convoys for protection. [Answer] As a pirate, I would want to have a mechanism whereby I could administer the 'lamprey treatment'. ![Lamprey style](https://i.stack.imgur.com/e4Huh.jpg) Might require a delicate touch from the operative to be effective beyond entry. [Answer] Cargo would be strapped down for the long time in zero-G in a vessel where position of center of mass is critical for precise maneuvering. It's also possible that the hold of a large freighter would be unpressurized. Also a sudden hole in the side of the craft doesn't mean that everything is jettisoned, the gas inside will rush out but the heavier objects take time to get moving. A quick vent will also have the air move around the slow object instead of pushing it out. [Answer] First of all, the cargo and the crew will have entered the ship somehow. That means that there is a door. There have been quite some movies that sported some kind of fabric covered tunnel that can be secured on the side of the vessel to be boarded. Since your pirates will plan to do such boardings more or less frequently (it being their profession, after all), they will have a device like that. Now all they need to do is open the door, by the handle, if possible, or with some force, and they are good to go. Of course there would also be the possibility to take over the cargo vessel completely. That would save quite some time dragging cargo around, plus they had a nice ship to sell. [Answer] *Tractor beam* as used repeatedly in Star Trek. Pull the ship in close were you make some impromptu passages, or pull the ship into a cargo bay and lay siege. A tractor beam is simply a sci-fi version of grappling hooks. Grappling hooks were standard fare of pirates. [Answer] A version of the Roman Corvus on the pirate vessel would be needed. The ship would have a set of grappling arms to attach itself to the cargo ship, and the Corvus would provide a cutting head to breach the hull and a pressurized tunnel into the interior of the "enemy ship". (think of an extendable pressure tunnel with a cutting head on one end). Once the Corvus had drilled/burned/lasered its way through the cargo ship's hull, the pirate ship could increase the air pressure on board to blow the hull section away and waft the boarding party onto the cargo ship. Once they collected the booty, lowering the air pressure in the pirate vessel brings the boarding party back. Once the inner airlock of the Corvus is secure, the cutting head is retracted (breaking the seal between the Corvus itself and the cargo ship) and the grappling legs are released, "blowing" the pirate ship clear of the cargo ship, and giving the cargo ship crew something more important to think about than giving chase. As an incidental, the Marines or police would probably use something similar to send their boarding parties aboard pirate vessels. [Answer] Why is the cargo hold pressurised in the first place? It would prevent explosive decompression if it were not, and would be cheaper to build the ship. You may have a pressurised hold for carrying animals or whatever needed it, or they might just have pressurised cargo containers in an unpressurised hold (the same way we have refridgerated containers on cargo ships). If i was in a space battle, i would depressurise the ship and use space suits. Nothing would catch fire and no-one would get sucked out. [Answer] I would simply develop a virus to inject inside the target vessel (maybe by communication, or maybe with a little drone witch goes to connect to some terminal outside the ship, or even cut its way to the wires) and then just board as you would with a normal ship; just do it before the attacked vessel as the time to restore the system. Obviously this mean you KNOW the system and the blueprint of the target ship, so you would be very selective, or there should be some sort of "pirate hackers" that sell that virus/drones. [Answer] The pirates would use the deadliest weapon known with application in space. This is, of course, the can opener. For ease of application, large can openers are preferred. Spacecraft will be made of thin materials, to save on mass and to thereby reduce the energy expenditure at propelling any spacecraft up to cruising velocity. This also means any gunfire will have bullets punching through internal walls and exiting via the outer hull. Very rapidly the ship will lose air. Space pirates only need to match velocities, pull alongside and knock on the airlock door, waving their can openers and hand guns. The threat would be immediately apparent: Open up or we will open you up and vent all your air. Now there is one problem with the OP's scenario. The cargo ship is large, obviously carrying a lot of valuable cargo, ripe for the picking by space pirates, but the space pirates themselves are flying in a small spaceship. The whole object of piracy is economic, i.e., to make money by stealing cargo from otherwise helpless vessels. Unless a small amount of that rich cargo is exorbitantly valuable, then this act of space piracy isn't economically viable. Take your can openers and go home. Except the space pirates will probably do real pirates do. namely, force the cargo vessel to change course and head to a location where the cargo can be transshipped and redistributed to destinations where the space pirates sell it and make a handsome profit. Otherwise you're out of the space piracy business. This is glamorous version of space piracy. A more 'realistic' version would be that the cargo freighters loaded to the jets with rich bounty, will be robot vessels. There's no need for a human crew. Besides humans take up a lot of space and they need roughly a ton of life support per person. A waste of good propellent and energy to dispatching a manned vessel across space. Also, humans will have to be paid. Robot freighters are so obviously the way to go. Do the space pirates turn up threatening the computer systems to heave to and prepare to be boarded? Of course, the space pirates will have the same problems. So the most likely scenario is a space pirate vessel, entirely computer controlled, matches velocities and dispatches a robot to board the freighter and reprogram its navigation systems to change course for the pirate base. Piracy is a business and will be run like a business. The Galactic Jolly Roger Corporation will continue launching its pirate drones to intercept innocent cargo freighters and then redistributing the pirated plunder to the outer colonies until such time as they can no longer turn a profit. The company would then be wound up and taken off the stock exchange of Capella VII. Actually the simplest, and also the most profitable way of doing space piracy would be to hack the navigation and control systems of a cargo freighter. When the right moment happened during its voyage this 'hack' would take control and steer the vessel to the pirate base. Sorry, no glamour, no piratical hi-jinks, and no Yo Ho Ho. Just the cool headed mechanics of commerce, astrodynamics, and robot vessels with a dash of cyber-crime. [Answer] Patch-able Airlock The problem of using an external airlock to board the cargo ship, is that once you disembark you have 2 options: 1. Leave a gaping hole in the side of the cargo ship. This might be okay (you're pirates after all!) But will lead to the crew getting a reputation for killing innocent cargo-crew and would increase the chance of cargo ships carrying weaponry. 2. Leave the airlock behind This however limits the number of cargo ships you can attack to the number of airlocks you carry. Solution Having deployed your airlock (probably using a grappling system as earlier answers have postulated) and stolen all the precious loot of the cargo ship, patch the hole you've left behind! Even if its just a canvas patch (as used in The Martian ) to prevent the cargo ship depressurizing. This reduces the risk to cargo ships overall and would reduce the chance of them carrying weapons. Hope this comes close to an answer, this is my first time posting to worldbuilding, so any advice would be appreciated :) [Answer] They could coerce the crew of the transport ship to let them board via threats and intimidation, or by good old-fashioned lies. [Answer] First think would be to stop the ship. Eather by threats, intimidation, promises of no harm to their crew or by force. If it comes to violance primary targets would be the engines and communication. Once the ship is crippled and silenced, boarding and plundering will be piece of cake. [Answer] Hey Samuel so there's a number of ways to go about robbing a merchant ship blind of all their goods. the first way is to use electromagnetic weapons like an emp gun/torpedo etc to shut down a ships systems whether fully or temporarily it depending on how good the technology of the time period and then having a boarding party board the ship through its airlock armed to the teeth of course and then either imprison the crew or dispatch them so the pirates can take all the cargo or the whole ship. the second way would be something like having a smaller boarding ship with a drill like piece in the front and ramming it into the merchant ship and then the drill would open depositing the pirates inside basically making a hole and plugging it with a ship. third way just shooting their engines and either going through the airlock or using a breaching cube which basically is a pressurized cube that attaches to the ship using magnets and your crew is in the cube you cut into the ship no depressurization you stack all the cargo in the cube and the part that connected to the ships hull you cut seals shut and the cube detaches for your pirate ship to pick up leaving the empty cargo hold depressurized and open to space. by the way what do you need this for? writing a sci fi book or something? :) [Answer] Ramming speed! If it's a private merchant ship, then its hull will likely be thin and made of a cheap material like aluminum. Have a pirate ship with a nose like a brass paper fastener. e.g. <http://cdn.www.officedepot.com/pictures/us/od/sk/lg/909432_sk_lg.jpg> Pierce straight in, then separate, making a hole. Then send in guys with suits to tie cables to whatever you want to take, hoist them back to the ship, close the cutter, and leave. Yeah, the interior will depressurize, but so what? If you are worried about any cargo leaving the hole, have a funnel around the cutter to collect it. In and out before the Space-Police arrives. [Answer] Magnetic grappling hooks, disable the engines and dock, shuttles that adhere to the hull and then cut through, infiltrate the crew, wormhole (which technically isn't teleportation, hack a bio printer and print clones, hack a 3d printer and print robots, hack a robot that is already built, hack the ship and get control, psychic control of a crew member, blackmail a crew member or some other form of traditional coercion, pretend to be dead in space and trick someone into docking, grappling hooks that 'cold vacuum weld' to the hull (it's real google it), psychic hallucinations that trick the crew (like psirens in Red Dwarf), disable the engines and starve out the crew. ]
[Question] [ This is set during the Renaissance, a mostly normal European setting. Magic works through controlling the flux of energy. A mage can't simply create energy, but he can store and change it. Most mages will meditate in front of water barrels, draining heat from the water until it turns into ice. A regular mage can generate about two barrels of ice per week. Would this method be able to generate significant income for the mages? [Answer] There really wasn't an Industry for ice until 1805 when the first guy named Frederic Tudor tried to sell ice from new England in the Caribbean. Literally nobody wanted to buy it, and he spent 13 years trying to sell it and ended up in debtor's prison on 3 separate occasions trying to convince people that they even needed it. He was so obsessed with the idea of selling ice that he began bringing chilled beverages to entertain guests, who often scoffed at the idea of adding ice to a drink... until they tried it. He spent 20 years of aggressively marketing ice to people, convincing (even paying) bartenders to popularize chilled drinks, teaching vendors how to make and sell ice-cream, and convincing doctors it was required to cool down feverish patients. His idea FINALLY caught on around the mid 1820's and he ended up rich after two decades of introducing ice as a new cultural phenomenon. The guy basically forced a meme in the age prior to internet. As odd as it sounds today up until that point people just really didn't care about drinking or eating cold stuff, there was somewhat a cottage industry in some cultures but it really wasn't something people wanted to pay for (packing root cellars with snow and such). Thing is, Ice as a product really didn't catch on in a big way until the 1840's, peaked in the 1860's, and was replaced by refrigeration in the 1900's. This all may seem like a distraction, but my point is people needed to be convinced they even wanted to pay for ice! The average value of ice in the mid to late 1800's was 10 cents a pound, or about $2.70 cents today, ice vendors made their profits by selling anywhere from 10 to 50 tons of ice a season (with a total income per shipment of 54 thousand to 260 thousand dollars.) So a few barrels of ice a week wasn't worth much in the 1800's, (a few dollars) and wasn't really worth anything prior to the 1830's (nobody wanted it.) But see, that's the REAL WORLD history of ice selling. You are writing a fictional world. So you got cash strapped mages who make ice as a byproduct of their work. So these mages decide to make up some snake oil, they start a rumor that "mage-ice" is super duper special compared to "normal ice." Chock full of good humors and invigorating spirits and what-not which are "rumored" to extend ones life, improve ones looks, and boost ones intelligence! (never mind the person who started those rumors is the ones selling the magic ice!) It becomes "fashionable" for Nobles to show off their clout by outbidding each-other and engaging in petty little squabbles to have a house mage on staff so they can have as much access to this wonderfully magical substance as possible. (in other words your mages do just what Frederic Tudor did in the 1820's and convince people its something they even really want to buy) [Answer] > > Would this method be able to generate signficant income for the mages? > > > Yes, it would. In a time when electric power was unknown, this would be the only viable way to have ice made easily available for many latitudes. [The ice trade would start a few centuries earlier](https://en.m.wikipedia.org/wiki/Ice_trade). Ice created by magic would help preserve food anywhere in the world. Just this alone would be a major revolution. It would change the economy for food markets as well as for nautical exploration. Seriously, go read First Voyage Around the World by Antonio Pigafetta. After months onboard sailors would trade a king's ransom for a dead rat because it was the freshest edible thing available. Ice has other uses as well. Medically, it can be used to treat rash and first degree burns, for example. Doctors would also use it to fight fevers. Barbers could press ice on a client's cheek after removing their teeth (barbers were the dentists of the past). Gastronomically, asides preserving food, it is used in the making of ice cream. Ice cream is as old as the ancient romans, but you had to climb a mountain or wait for a snowy winter before the ice trade became a thing in the 19th century. If you think this is silly, remember that during the crusades people would kill for a pint of sugar. People would find other creative uses for ice. If you want to take water upstairs, for example, you have to move the weight of the water + its container. With ice blocks, you don't necessarily need a container. And if you need to move heavy furniture around, perhaps placing it over a slab of ice makes things easier. So long story short, I think not only the mages could make a living, they would be wealthy, upper class citizens. [Answer] TL;DR The magician can earn a living quite well by producing ice, but don't expect him to get very rich. --- We don't need to speculate. Natural ice trade is widespread and very well documented in medieval and modern ages -at least in Southern Europe-, and we just need to check for ice price to see what is worth the ice the magician can produce. According to [this paper](http://www.raco.cat/index.php/AnnalsGironins/article/viewFile/54463/64951) (in Catalan) the official price to sell ice to the public in Estanyó (near Girona in Catalonia) was 7.5 denier/kg (cheaper than wheat, bread or wine), and that was about 1/6 of the daily wage of an unskilled worker. According to the OP, the magician can turn two barrels of water into ice per week, although we don't know how big are those barrels. Assuming they are 100 litres barrels, the magician is producing about 1500 deniers/week, or the equivalent to 32 unskilled worker daily wages per week. That is, the ice he produces in a day is worth the wages of 5 unskilled workers. From this amount we should detract the costs of distribution and taxes, since somebody needs to cut and sell the ice and ice was a heavily taxed industry. I just used data from one place, which was just a village not far from ice sources. Probably in large cities more distant from ice sources the magician could get a better rate. [Answer] Anywhere there is a fishing industry will have a market for ice. So, large rivers, coastlines and islands. Ice gets its value there from preserving fish, allowing transport for a few days to markets inland. In contrast to luxuries like cold drinks and ice cream, this puts it squarely into the realm of the essential - both for the inland city dweller whose life depends on adding protein to an otherwise poor diet, but also for the fisher people whose livelihood depends on getting their catch to market. There's a distinct type of architecture known as an ice house, often built near the harbour pier in Scottish seaside villages. [![enter image description here](https://i.stack.imgur.com/UpBkL.jpg)](https://i.stack.imgur.com/UpBkL.jpg) [(image source)](http://hopemanhistory.org/hopeman-ice-house) You can push the timeline back a bit earlier than 1805 ... [1785 in Scotland](http://www.mouthofthetweed.co.uk/salmonice.html), from a man who brought the idea of preserving ice home from travelling in China - you might follow it back to China to push the timeline back further still. From the linked article: > > At least 7,500 cartloads, or 2,000 tons of ice were needed to fill Berwick's ice-houses. During the 19th century, the ice needed was usually sourced from the River Tweed and harvested from ponds created in the district specially for the purpose, such as those at Heatherytops in Scremerston, about three miles south of Berwick. If sufficient amounts of ice could not be found locally, the Berwick Salmon Fisheries Company imported supplies from Norway. As early as 1833, there are records showing that ice was imported from Norway following a mild winter. The last ice-ship came to Berwick from Norway in 1939. > > > Having a local maker would be much more convenient than an international transport and storage system. Ice houses quickly spread round the country from that first one, [many still survive today](https://www.coolingpost.com/features/luxury-ice-house-home-for-sale/) though they fell into disuse when refrigeration came along. The fact that custom buildings were worth building, insulated well enough to preserve winter ice through the summer, gives some idea of the real value of ice. [Answer] Ice was [extremely popular](http://www.theflorentine.net/food-wine/2009/07/chilling-out-in-the-renaissance/) in Renaissance Italy. It was added to wine to cool it down, used to keep wine chilled, both in the wine cellar and in the cup. Eventually a cup designed to hold ice or snow while another cup of wine was placed on top. They also used ice and snow to keep fruit, juice and other refreshments cold. [Ice cream](https://www.florenceinferno.com/the-invention-of-ice-cream-in-florence-history-and-legend/) would be another source of income. In Florence ice cream and sorbets were refined and extremely popular amongst those who could afford it. It was also used for special events among the rich in France and several other Southern and Central European countries. So yes, money could be made as long as the mage is in a warm place. [Answer] Heck yeah! The [ice trade](https://en.wikipedia.org/wiki/Ice_trade) didn't even begin until 1806. Before then, some ice (never large amounts) was captured from the Alps, etc., during the winter and stored (likely poorly) for summer use. Your mages would make a boat load during the summers (and not a penny during the winter), unless there are so many mages that it gluts the market. Out of curiosity, though, why water? If the mages are drawing thermal energy from water, why not from fire, which is obviously more thermally dense? If you started with boiling water, the amount of energy drawn from two barrels to freeze them wouldn't be equal to draining a fire in a couple of minutes. [Answer] > > Would this method be able to generate significant income for the mages? > Yes if he uses his brain. > > > Most of the population during Renaissance didn't have to worry about storing food, as they barely had enough to consume each day. Things change if your mage operates in the surroundings of a court. And I suppose he already does, following Merlin example at the court of King Arthur. In the past snow was collected and stored in cellars, and its use was mostly dedicated to prepare sorbets and ice creams for the courts. Your mage can enter this business, actually getting appointed as "official sorbeteer of his highness the of ". There he can also use ice to improve storage of food needed for the court, and even provide ice for the times when somebody gets ill or hurt. The above also suggests that your mage can have better fortune (read less competition) in southern countries where harvesting natural snow is somehow more difficult. [Answer] In this time period, ice is likely going to be popular with the very rich for its rarity and its ability to preserve delicate foods so they can be eaten out of season, especially if wizards are rare enough that someone's only going to be able to buy a few dozen ice barrels at a time and if there aren't any nearby tall mountains for easily-accessible snow. Back in Roman times, the super-rich would hire fast chariots to speed the asparagus harvest (early Spring) from the Tiber river high into the Alps so that the snows would preserve the asparagus until the feast of Epicurious in Fall, and they'd pay insane amounts for the service. [Answer] The availability of ice in the middle ages would have changed society out of recognition. Having refrigeration would mean that every foodstuff could be stored and eaten at any time of year. It would mean that humanity would not have depended on seasons. Almost all the great festivals we have are to do with seasons. True many of them stem from a long time before the renaissance, but they are gradually being ignored and forgotten. Perhaps we would not even notice the coming of spring if we had been living with fridges for hundreds of years. ]
[Question] [ In H. P. Lovecraft's The Case of Charles Dexter Ward (1927), a character is resurrected approximately 150 years after his death and (being an accomplished and intelligent wizard), decides that before he restarts his magical research, he will go on a quest to educate himself on recent historical, political, scientific, etc. changes in order to not be the proverbial "fish out of water" in the 20th century. Even with all of the 20th century books he absorbs at his destination time, he is still perceived as significantly socially different in a negative way (his handwriting looks like it belongs in a museum, he makes "odd" gestures, and he has huge gaping holes in his knowledge of recent pop culture phenomena), which draws the kind of attention to him that he very much wants to avoid. What resources could be used by a person who knows that they will be moving forward approximately 150 years in time (the manner is open, whether physical resurrection, cryonic sleep, jumping right into a time-space anomaly, etc.) to prepare themselves cognitively to absorb the new learning they will find on the other side and become a functioning member of that society with the least amount of post-time-travel effort or time? Assume that time travel only works one way, so grabbing a future textbook or newspaper is out of the question, but there is some opportunity to prepare for future learning by learning things beforehand. Assume, like Lovecraft's character, any future time-travelers have at least several years to prepare, so "get a PhD in biology", "get trained as a master automobile mechanic", or "study Zen Buddhism meditation practices for five to ten years at a monastery" are not out of the question. Are there academic subjects, practical skills, etc. that are likely to be highly useful in "learning how to learn" things in the future? One thought I had was that learning multiple languages and/or gaining a grounding in academic linguistics might give someone the ability to "hit the ground running" and learn the languages/dialects of the future more quickly. Are there any other things that a future time-traveler could study? Assume a roughly 20th or early 21st century departure time as the latest time our traveler could finish their pre-travel education, but things that were available and could have been learned from educational providers centuries ago (even if the average person then did not) are a plus. [Answer] # Primary: Sign Language, Braille, Abnormal Psychology, Acting The best thing to do to avoid suspicion is to stand out like a sore thumb. They could pretend to have been previously handicapped in some way. No one would blame a deaf man for not knowing pop songs and pop culture references. No one would blame a blind man for not knowing about the latest movies and how to use a smartphone. No one would blame a schizophrenic person for not accepting that we put colonies on Mars decades ago. Acting is the skill that will let them pull these off, and they have a few years to prepare their special identity. They should learn and immerse themselves in the role they pick; eg.if it is blindness, they should live blindfolded and experience the use of braille. Although they should not expect braille, sign languages, etc, to remain the same in 150 years, the immersion allows them to have an impeccable performance. # Bachelor of Applied Science Degree Another useful skillset: skills in working with technology. By educating themselves on programming and using/making hardware, especially the basics, the foundational skills the person develops will still serve them well in 150 years. Even if the technology itself changes wildly, the principles behind solving problems, and working with developing on systems will not. With these skills, the person will have less trouble understanding the basic working principles of any new technology in the future, and will be able to figure out how to use the basic technology much more easily. To get the basic skills, it should be enough to spend a few years to get an Electrical/Software/Computer Engineering degree and working a job /internship or two as a software/electrical engineer. and if the world had gone full apocalyptic in 150 years, they would be able to use the basics to make a talking volleyball as a companion, and perhaps repair a power generator or two. # Insurance: Hacking and Cash But those alone won't let a supposedly dead, full grown person from a 100+ years ago not raise flags on the records when they show up looking very much alive. They will need to either obtain some hacking skills, or, much more easily (and much more reliably, considering the changes in computer security and design in 150 years), enough jewelry or valuables to pay off the local government or cartel of a shady country for some new identity papers, no questions asked. The jewelry/valuables should be well-made, rare, and have some sort of historical value. If it is kept in pristine condition for 150 years, chances are that collectors will pay large amounts to obtain them, and this will come very much in use for paying for things in the future. ~~One other thing to do in this situation is to invest (gamble) a small portion of their wealth in a small amount, but large variety of different untraceable cryptocurrencies (no stocks, those are much more conspicuous). Given enough time, one or two of them may survive and grow to be worth astronomical amounts compared to how much they are worth at their inception.~~ After some consideration, and from thoughts mentioned by the comments, the probability of a cryptocurrency surviving is quite small, and due to 150 years being a long time, changes to security could make it very hard for the person to safely withdraw and use the currency without divulging their identity. The return is not worth the potential risk, so jewelry and collectibles would still be more reliable. # Fingerprint Modification, Hair Implants, and Someone Else's Eyeballs If they end up waking so far in the future, bio-metrics may be [prevalent to the security of the new world](https://www.forbes.com/sites/forbestechcouncil/2020/03/16/the-future-of-identity-looking-ahead-to-the-2020s/#50072ee43ecc). If records of them already exist in the present time, they will need some replacement fingerprints, hair implants, and eyeballs to potentially fool fingerprint scanners, DNA scans, and iris scans. # Carrying Out The Plan With whatever body condition they pick, they can step out into the new world. Firstly, they will 'dig up' a century+ old 'familial inheritance', and sell some for a reasonable price to the nearest shady pawn shop. They will then need to pick up a set of identity papers and records for their new identity, along with identities listing out their disability. As @cmaster has mentioned, cryptochips or an equivalent, which may be inserted at birth, may also be present as a form of identity verification in the future. In this case, they will have to ask for an implant of a fake chip while they pick up their papers. Then they will visit a hospital, and 'correct' their disability with their 'newfound' wealth. As @Philipp has mentioned, some may be suspicious as to why they would take so long to correct their handicap, in a world so advanced. I have doubts as to whether 150 years is enough to solve the question of poverty, so they can probably claim that they were too poor to afford treatment. If, however, the world has somehow implemented universal healthcare, in every country, they can use their acting skills to fib. Maybe they were kidnapped by a gang as a child and never got fair treatment. Maybe they were living on that one island that never learned. Maybe they wanted to remain blind because reasons, but the person they love has been diagnosed with a fatal condition, and they got the surgery to see them one last time. A good actor/conman can always figure something out. If any of their behavior seems to be strange in the future, they can say that they have been rehabilitating from whatever condition they had in the past. To rehabilitate themselves from the Cultural Shock they will inevitably experience, they can then use their funds and identity documents to attend the future equivalent of a College or University. It is also recommended that they pick up the latest copy of a fashion magazine, and do some window shopping to fit in with the fashion trends of the century. --- [Answer] Religious Studies It's not a joke. Basically, no matter what happens, you're going to be thrust into a situation that you don't know how to deal with if you get chucked into a future 150 years from now and you want it so that you can shift the situation into one you do know how to deal with, and furthermore you also want to be able to learn how to deal with the future, and you'll need friends and resources to do that. Religion, well at least certain religions, have remained unchanged for at least thousands of years. There's very little evidence to suggest that they'll be changed in a mere 150 years. Thus your character should devote himself to the studies of whatever religion he happens to be affiliated with, and when he arrives in the year 2170, he'll have a useful skill set to join back up with his religious friends and count on them to help him acclimate to the rest. [Answer] Learn [Speed reading](https://en.wikipedia.org/wiki/Speed_reading) Your character is at a clear disadvantage here. Whatever he learns would be only of a limited use in the future, and as you stated in the objective, he will need to be able to learn as much new information as possible in a short amount of time. So the learning techniques, such as the ones improving perception and memorization would be of great importance. Still, if the future would be more technologically advanced than we expect (for example, there will be Matrix-like neural links), speed reading would turn out to be only as good as a superb equestrian skill transferred from 1800s to our early 2000s. [Answer] ## Travel the world Future shock is a form of culture shock. The best way to prepare for culture shock is to experience it. It shakes loose your notions of what is "obvious" and "everybody does that". Avoid the tourist infested places. People there adapt to the tourists rather than the other way around. If possible, learn the local language. You can't really understand the local culture otherwise. Then do it again somewhere else. After two or three foreign cultures, return home and try to see your own culture with foreign eyes. Spend enough time on a nude beach to become comfortable with it. There is a reasonable chance the future will be clothing-optional. There is also a chance this will be wasted effort, but spending time on the beach isn't much effort anyway. [Answer] There are some good answers here, but I'd like to take a different approach. 150 years is a long time in terms of technology standards. It also a very long time in terms of cultural standards. It is a short time in linguistic, geological and genetic terms. Since we have no how technology will change in 150 (even the most successful predictions of technology of our day were always coupled with wildly incorrect notions), investing large amounts of time in science fiction probably isn't going to help. To compare, look at science fiction in the late 19th century (~ 150 yrs ago) vs. the world today, it doesn't help that much even looking at science fiction in the 60s, 70s or 80s. We have unimagined connectivity via the internet and the ubiquity of fast computers while no flying cars, no butler robots and no spaceships. Since predicting the future of technology and its sociological impact is so difficult, I think a huge time investment in this domain won't help and may even cause issues if the reality is vastly different than expectation. Since as mentioned 150 years is a very short time scale in linguistic, geological and genetic sense, huge time investment into predicting the outcomes of these won't help much either. New languages can be learned predicting how a language will evolve isn't possible without knowledge of other things like historical events. Consider the major languages of the world today, I can't speak for non-European languages but I find that literature and newspaper articles in many European languages to be just as comprehensible from the 1800s as it is today and I suspect the same is mostly true for other widely spoken non-european languages as well. Geologically speaking 150 years is moot so all the major features that are here today should be here in 150 years, and if they aren't there are probably bigger problems to contend with than standing out in a crowd. Genetically, unless a technological singularity occurs we will be genetically identical, and if a singularity does occur than you'll stand out no matter what you do. This essentially leaves cultural standards and again the changes those will take are rather unpredictable. However, I believe that cultural changes will be the biggest challenge in adapting quickly. Since there are ways to work on this I think this is the area to focus on. By travelling, living among and adapting to many different culture a person would be able to hone in on being flexible. Learning to rapidly pick up on social cues as well as being forced to have a more open mind with regard to cultural mores and norms will probably be the most important skill for rapidly integrating into the world of tomorrow. [Answer] The most important thing for them to lean is... Delegation. The best way for someone to prepare to settle into a new culture is for someone from the culture to prepare them a "quick-start guide". Rather than just learning excessive skills which may prove outdated and redundant, the character should arrange for a small team (funded by an annuity or trust fund) taking "the long way around" to prepare a short report of important cultural, political or social events each month - just snippets / headlines, and a list of "significant" books, plays, movies or games that should be experienced in at least an abbreviated form for cultural purposes and references. Once your traveller arrives, they then have a rough summary of things they would be expected to possess at least a passing knowledge of had they lived through time normally. If this were to average about 4 sides of A4 per month, then these notes would wind up about 5 times as long as "War and Peace" / the combined "Lord of the Rings" trilogy and "The Hobbit". (Or 70% longer than [Worm](https://en.wikipedia.org/wiki/Worm_(web_serial))), and would take about a month of constant reading to plow through. Catching up a synopsis of the "culturally significant" media, if we estimate distilling it down to about 3 hours of content per month missed (or 6 minutes per day), would take an additional year and a half. Your traveller won't be a pop-culture master by that point, but they won't be a complete neophyte. They will also have developed opinions and interests to explore further. Also, make sure that the summaries are regularly curated to remove "redundant" cultural references. For someone arriving in 2020, [the Spice Girls](https://en.wikipedia.org/wiki/Spice_Girls) is probably still worth having heard of, while [Babylon Zoo](https://en.wikipedia.org/wiki/Babylon_Zoo) would be a bit of a waste of time. [Answer] *HISTORY & LITERATURE:* First, I agree, you should invest a lot in a diverse portfolio that is likely to leave you with assets in the future. But if you don't want to seem odd in the future, make a policy of - well - consciously being odd in the future. Get skills that are timeless - learn history and literature. There are always people who will seem out of place, and if you let people know up front you're an ancient history or english professor obsessed with reenactments, your knowledge won't (hopefully) be out of date and strange mannerisms will just seem charming. "well, of COURSE he wears a cravat - he's in CHARACTER!" You can pretend to be ignorant of social customs while you actually learn them. [Answer] He should read a lot of science fiction, especially stories specifically about future social changes, and stories about characters who are fish out of water in their societies, and he should read the works of futurists predicting what future societies might be like. If someone knows that their physical body will travel to the future, they can set up a fund to be invested for decades and centuries, and to be at the disposal of someone who had specified physical characteristics such as their fingerprints, completed genome, retina scans, and iris patterns, and then apply for those funds when they arrive in the future. If they have control over where they will appear in the future, they can buy a house where they want to appear in the future, and create a foundation to maintain that house for them and their fictional descendants. they give the house to their foundation along with enough money for the foundation to pay the mortgage and taxes. And the property will be locked up and only the foundation members and the fictional members of his family will have the keys and/or codes to enter the house. So he can arrange to travel one year into the future at a time, spend a week in the house presumably having used the keys and codes to get in, and study recent events and cultural changes via television and computers for a day or a week or something (and maybe order more fashionable clothing to be delivered) and then go back into suspended animation or his time machine or whatever to travel another year forward in time. That way when he reaches his final destination in time he will be reasonably caught up with changing accents and vocabulary and pop culture. with such a method he should be able to keep track of predictions by futurists and see how changing events change those predictions and thus find get a better and better idea of what society in his chose future year will be like and how to fit in to that society. Or, if he has enough money invested wisely enough for a long enough time, he can establish a new identity as an eccentric reclusive millionaire, billionaire, or trillionaire, or quadrillionaire (assuming that the future society still has money and that his assets have not been confiscated). For example, if invested money grows at a rate of 10 percent per year, it will take 7.2 years to double in amount, and after 72 years it will have doubled ten times and now be 1,024 times it original value. So after 72 years each dollar will be 1,024 dollars, after 144 years each dollar will be 1,048,576 dollars, after 216 years each dollar will be 1,073,741,824 dollars, after 288 years each dollar would be about 1,000,000,000,000 dollars and so on. Of course with inflation the rate of growth will be much slower. At a growth rate of 5 percent per year after inflation, it will take about 14.4 years for the amount to double, for example, so the time to increase by a specific amount will be twice as long as in the previous example. [Answer] ## Set up a foundation and trust 1. Find yourself a reputable financial advisory institution with a long history. A firm that has been family-managed for multiple generations would be best, as this is going to have a stable tradition. * if you have a good, trustworthy friend in the financial/legal profession, tap him for help/advice). 2. Assuming you're already rich enough to have financial independence, use their services to set up a financial trust * Set strict rules for investment so that the money is as safe as you can make it, while also making it financially worthwhile for the firm to maintain it indefinitely. Make sure the rules are clear that, when you come back, you will be able to provide adequate proof of your identity for this trust to be ceded to you or otherwise support you adequately. 3. Again, assuming you have the funds or can persuade others to do it, set up a charitable foundation * Dedicate this foundation to helping people suffering from memory issues or identity issues, especially those that make them forget large parts of the past or feeling that they belong in another time. Make it part of the charter of this organization to collect pop culture information in easily digested form to help people with memory issues or related problems 'get up to speed' on current events. * If you put the right people in charge, this foundation should be self-perpetuating, and you can make sure to insert criteria into the founding charter (or founding family tradition) that will advantage you in particular once you come back. * If you're lucky, depending on how you want to structure your world building, the time travel bureau may be interested in clandestinely supporting this foundation, as well, for mutual benefit. ## (Optional) Make a bet * Bury (or otherwise ensure the safekeeping of) a number of time capsules. + These time capsules will contain modern day items which you can obtain relatively cheaply that you are pretty sure should fetch a premium as collectors items when you return. Bury them in conditions that will ensure they will be in peak condition when you return so as to be of as high value to collectors as possible. Obviously, this is a gamble, as no one knows what collectors will end up valuing, but you can definitely make an educated guess on this. [Answer] Learn to cook. The taciturn sous chef. A useful person to have at your side. And he knows some retro prep tricks that are all the rage in the city! Where did he learn them? Maybe his grandmother? You think he might be Mennonite or something; he has a funny way of putting words together. But his instinct for those old school ingredients! In the future people might not drive, or speak to each other, or need to wash, or want to read, or go to church, or have sex. But there is a certainty: people are going to eat. And if they are going to eat they need food, and some one to make that food. Your guy can be that guy, and people will be happy to pay him to work. [Answer] # Social skills Learning any hard skills is a total shot in the dark. You have no idea how the world will change over the course of 150 years. You can't predict what technological advances there will be and how they will affect society. You can't even know that there will be advances. It is just as well possible that you find yourself in a post-apocalyptic world where technology and society have regressed and where you face completely unexpected threats and challenges. But there is one thing which never changed much throughout history: Human nature. * Getting people to perceive you in the way you want to be perceived. * Assessing people's true intentions and predicting their actions. * Communicating efficiently, even through language barriers. * Telling convincing lies and noticing when people lie to you. * Finding people's buttons and knowing how to push them. * Negotiating mutually beneficial agreements and making sure the other party sticks to them. As long as there are humans, those skills will benefit you. --- By the way, one TV show you might want to study for your project is Doctor Who. It is a show which constantly switches between very different futuristic and historic scenarios which all work very differently. The characters usually start out completely unprepared for the scenario of the week. Take notes which skills benefit the protagonist in every scenario they find themselves in. [Answer] Learn as many languages as you can, from different language families and type. For example, learn at least one tonal language such as Mandarin. There is no way to know which language or languages will be the basis of communication in 150 years. If you are lucky, it will be a language you know, and you only have to deal with 150 years of shift in meanings of words etc. If you are multi-lingual any glitches will be explained away as the result of learning whichever language you are speaking as an adult. Even if none of the languages you know is directly useful, language learning practice will help you learn another language, and the more languages you know the better your chances of there being automatic translation systems between the languages you need and one of the languages you know. [Answer] Cultural anthropology You should major on [cultural anthropology](https://en.wikipedia.org/wiki/Cultural_anthropology) and do lots of fieldwork. This would let you directly practise skills needed to observe and understand foreign cultures and have a rich methodology you can study to back it up. And as another answer pointed out "future shock is a form of culture shock" so it would also help you deal with mental issues you might experience. You'd also learn how to be out-of-place in a foreign culture without annoying the natives which might be important skill to have. There is also possible future employment in thoroughly understanding and being able to explain obscure late 20th - early 21th century cultures. Acting Probably not worth actually formally studying but some amateur theatre and courses in specific forms of acting would have value. Acting is basically about passing as someone different from who you are without seeming out of place. Some forms of theatre achieve this by following accepted theatrical forms and some by direction but if you focus on less formal and directed forms and put effort to it, it will serve you well. You'll learn to pay attention to how people act and speak, to understand why they do so, and adapt it to your own mannerisms and speech. You'd also learn to rapidly adopt dialects and expressions. Fortune telling is an interesting and maybe more effective variant of this. [Cold reading](https://en.wikipedia.org/wiki/Cold_reading) would be highly valuable skill to have. You'd learn to talk in manner that suggest that you know what you are talking about when you do not. Or more specifically and very importantly, how to speak without it being obvious you are avoiding exposing your ignorance about things you really should know. You could do this as a hobby. Being able to convincingly act as a person few centuries back and being a medium in touch with the spirits of centuries past are also both ways to make a living that might still exist. And both would justify occasionally acting like a person from the past without it being out of place. Linguistics Study of languages and how they change over time would help you to recognize and learn the inevitable changes to language. Hearing that the words are different is nice, recognizing what the change is and how it likely changes other words is better. Basics is enough and can be justified by your study of cultural anthropology. And having basic understanding of multiple languages of different language groups has obvious value. Even if they still speak English it might be one with added Chinese elements in it. [Answer] My immediate, probably unhelpful, response is to say that it would be impossible for a person to predict what changes would occur over 150 years, and therefore impossible to know how to prepare for those changes. Perhaps it's worth thinking about then from another angle, if sticking out like a sore thumb is going to be inevitable, then they should lean into this and work on sticking out like a sore thumb in a way that distracts from the possibility that they might be a time traveller. For instance, if they could learn to perfect some kind of foreign accent, they could excuse any of their unfamiliarity with recent pop culture by reason that that film or song or hologram or whatever wasn't popular in their home country. [Answer] Realistically, 150 years into the future is far enough of a jump to invalidate your current knowledge. What you need to do to prepare for this trip actually is counterintuitive. You don't need to fill yourself with knowledge. What you need to do is leave everything behind. You don't need to acquire knowledge, instead you need to empty yourself, leaving what you know in the present moment. Holding on to what you were will not serve you. This may sound abstract, but in fact it is anything but. What you need is to set yourself upon a path that will allow you to adapt to the unknown. There are many of these paths. I suggest: [The Eightfold Path, or Ashtanga](https://www.yogajournal.com/practice/the-eight-limbs) I suggest this because you will be as one reborn, except you are already full grown. So we need to begin the process of letting go of who you were, in order to become part of this new society. It surely can be done, humans are the most adaptable creatures on the planet, except for microbes, I suppose, and although society will have changed, humans will not. You need to learn how to become a tabula rasa, or blank slate. In Buddhism this quality is also called the Beginner's mind. ## The Yamas These are the qualities you should try to cultivate for your journey: 1. Ahimsa: This is the principle of nonviolence, both physical and emotional. 2. Satya: Honesty or truth. 3. Asteya: Nonstealing. Not just things in the world, but also abstract things like time, or joy. Don't take what is not yours, until it's given. 4. Brahmacharya: Technically this is celibacy, but practically it is more like continence. Don't lose yourself in the seeking of pleasure. Enjoy it, but don't chase it. 5. Aparigraha: Noncovetousness. Stuff is great, when you have it, not so great if you are preoccupied with it. You won't have any. Don't sweat it. The second limb of the path relates to self discpline. These are the ## Niyamas 1. Saucha: Be clean. 2. Samtosa: Be content. Be happy with what you have. 3. Tapas: Heat, in this context referring to cultivating the heat, the intensity to overcome your internal inertia. 4. Svadhyaya: Technically this means study of sacred scriptures, so write some stuff down and think about it. Take the time to increase your knowledge and contemplate your own observations of the Path. 5. Isvara pranidhana: Surrender. No matter how strong one might be, eventually you'll be weak and frail. We practices surrender, submission to the world, so that when that time comes, whenever it comes, you will not despair. ## ASANA Asana is what you would call yoga. The reason you do asana is to learn how to deal with being uncomfortable, to realize that often you can't make things better, but you can make them worse. The postures open and strengthen the body, so that comfort can be found in all places, in all positions. The skeletal muscles are controlled by you. Asana enhances this control. ## Pranayama This is the science of breath control. It is subtle. Master the breath. No downside. ## Pratyahara This is the beginning of meditation. Pratyahara is the practice of withdrawing from the sensory inputs. Pratyahara is part of how we stop reacting to things we see, smell, taste, etc. ## Dharana We've left the senses behind. Now we concentrate. Dharana is the cultivating of focus, to the exclusion of all else. To lay one's mind upon a thing, and nothing else. re ## Dhyana Now we are ready. Release the focus and think about nothing. Focus on nothing. It's just as useful a skill as the prior focus. Smooth out your mind. Here is where you can access intuition, innovation. Problems get solved here. Everything that has gone before is you getting out of your own way, eliminating preconceptions, and old patterns. ## Samhadi This is kind of hard to explain. You transcend the Self, which is a complex set of behaviours that you do when you're not sleeping. This is how one becomes a blank slate. This is where one leaves behind who they were. This is where one is reborn. All these practices are to facilitate your developing the Beginner's Mind. Now you'll be ready to step into the unknown, empty handed, because that's the best way to face it. All this is to teach you how to get out of your own way so you can become something/one new. Perfect for a dude going on a one way trip into the future. EDIT: As I said above, 150 years is a long time, in term of human societies. Our powers of prediction are not great, and ours in particular are skewed towards optimistic outcomes because we happen to have been born during a time of relative climactic stability, which allowed farming to be a thing, although there were [significant and culture changing variations](https://en.wikipedia.org/wiki/Little_Ice_Age) during that time. 150 years ago we were using fossilized sunlight for energy, via coal, but had yet to find the vast stores of oil, which, it turned out, was the Philosopher's Stone, something that you not only could burn to keep your butt warm, but also spin into cloth to cover it, as well as sprinkle onto your crops to make them grow much better, and then burn some more to take those crops into the city. Ironically, it's quite possible that the Philosopher's Stone might actually change the climactic stability that allowed civilization to arise, and it won't be around in 150 years. There's a bunch of difficult and expensive solutions, which may or may not work, as well as a final one which always works. Hopefully your traveller does not roll snake eyes on that particular roll of the dice, since it's a one way trip, hmmm? Really, you'd have to wonder why the future even woke you up, right? They don't owe you anything, you had your time. What skill or quality could you possibly have that is valuable enough to go to all this trouble, yet not so valuable that it was duplicated or replaced over a century and a half? ]
[Question] [ Can we increase life expectancy by replacing important organs for life such as the heart, kidneys, young blood, etc. (but not the brain)? Most organs can fail and, for the ones which we already have the technology to develop artificially, would it be beneficial even if the person is otherwise healthy? [Answer] No - not in a worthwhile way. Given the current state of medicine, organ break down is not your main problem any more. Operations to replace organs with artificial ones work, although there is still a non-negligible risk to it. Even if we assume that we can replace major organs affected by cancer and ignore the spread of cancer through metastases, there are more drastic limiting effects of irreplaceable body parts. Three parts of our body form the main problem, responsibles for ~75% of deaths in elderly people: * blood vessels: they run everywhere in the body from wide vessels as the carotis to extremely narrow capillaries in the brain. They age naturally and there is no way of replacing the smaller ones in less accessible body parts such as the brain. If they get clotted or burst, your suffer from thrombosis resulting in stroke, heart attack or other cardio-vascular symptoms. * nervous system: nerves are hard to replace, they actually die off, making elderly people lose capacities such as sensitive touch, hearing, temperature feeling and regulation etc. * brain: the main problem limiting life span or better to be said the life span lived with a certain quality of life is the brain's capacity. Altzheimer's disease, dementia, the natural deterioration of reflexes and mental constitution are all effects limiting the human life span automatically and most radically. Unless you can keep these mental effects in check, no organ replacement will make people life longer in a worhtwhile way of living. [Answer] ### TL;DR: No, as transplanting an organ have drawbacks. Replacing a functional organ is just asking for trouble ### Transplants can fail: > > Everyone talks about the success rates of kidney transplants. Rarely > do we talk about what happens when transplants fail. People will quote > the official statistics that 97% of kidney transplants are working at > the end of a month; 93% are working at the end of a year; and 83% are > working at the end of 3 years > <https://www.kidney.org/transplantation/transaction/TC/summer09/TCsm09_TransplantFails> > > > Those are just some numbers about current success rate of kidney transplants. 83% of success rate is very good for those who would die without transplant. But they are just disastrous if the people were healthy. ### Complications A transplant can have a lot of complications. Just for a heart transplant, you can get: * Organ Rejection * Infections * Graft Coronary Artery Disease * High Blood Pressure/Hypertension * Diabetes ### No long term support Here is an [abstract](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387387/) about long-term outcome following heart transplantation. It's not dramatic in current world, as people with heart problem are in the majority of cases quite old. But it's problematic for transplantation on younger folks ### Money cost Another problem is the cost of a transplantation. A surgery operation cost a lot. An artificial organ even more. Replacing every organ of every human would be just way beyond budget accorded to health organization. And this money could be spent way better on other fields. Organ failure is just one way to die. They are plenty others way to die, either environmental (accidents for example), or other diseases (cancer, ischemic stroke, diabetes...) [Answer] That depends on your definition of "life"... But the answer is probably no. If you replace the heart of a healthy human with an artificial one, that human won't die from a heart failure. But he can still die from cancer, stroke or a broken neck because he fell down the stairs. That means the overall number of deaths due to physical cause will be smaller, but not zero. The human body is already able to stay relatively healthy into old age if it's maintained and moderately trained. The same applies to our brains. As long as people have something to do in their life, most stay clear minded into old age. But if they lose that purpose or task, the brain power decreases just as much as an unused muscle. By replacing vital organs you can keep the body alive and minimize the numbers of deaths due to organ failure and unhealthy lifestyle. But those people might be no more than human vegetable if they don't have any reason to keep their brains active and trained to manage the basics of life. The more sophisticated a society is, the more likely it is that people lose their mental prowess. Our great-grandfathers (and mothers) had to learn many things about agriculture, observe nature and contribute to the family even in old age. Their bodies degenerated faster than their brains. In our current society, we learn a lot of stuff in school (most of which we never use in life), but we have computers, smart phones, calculators and navigation systems to do the hard thinking for us. After retirement many people lose any purpose in their life and their brains degenerate rapidly due to the lack of mental training. (This effect is called [Digital Dementia](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwjqgPWSo8XgAhWBgM4BHRx-DWEQFjAAegQICRAB&url=https%3A%2F%2Fwww.psychologytoday.com%2Fus%2Fblog%2Fmind-change%2F201507%2Fdigital-dementia&usg=AOvVaw3DLiO1Sq_sTI0dvXI0wCpO)) If this trend continues in the future, the degeneration of brains might set in even earlier in life and be more devastating, because all the gadgets that make life so comfortable mean people never need to train their brains. [Answer] What you consider to be important becomes dependent on what can fail without replacement. So ultimately your answer is the more specific problem of [Theseus' Ship](https://www.philosophy-foundation.org/enquiries/view/the-ship-of-theseus). * Once you have replaced the entire body (apart from the brain) with artificial replacements, are you still alive? * If you also replace the brain with an artificial unit are you still alive? * If you only replace the brain with an artificial replacement that to all other parties appears to be you, are you still alive? If the answer to all those questions is yes, then yes, replacing all important parts with artificial replacements will lead to longer life. [Answer] That would be a more or less definite "No" for both questions. There is leeway for a "yes" concerning some individuals. Obviously, when your kidneys (or your heart) are failing, your life expectancy with artificial kidneys (heart) is much better than without. For average life expectancy, it's a different story, and for absolute life expectancy, yet another. Surgical interventions (even narcosis without surgery) are a possibly lethal risk, so the extension of average life expectancy is limited by that factor. Replacing several organs is not just "some surgery" but a really awful darn lot of high-risk surgery. Thus, the risk (and impact on life expectancy) is relatively high. On the other hand, organs as-delivered by nature work amazingly well for an amazingly long time in most cases, which is pretty close to the total maximum. So the possible gains are not great. In summary, this will likely rather decrease than increase the average. Now, there exist ideas which are repeatedly being spread by uninformed and stupid people such as "life expectancy rises X years every 5 years, soon we will live 150 years" or "in 10-20 years we will be able to cure cancer" (the German Health Minister made that claim a few weeks ago). They're just that, ideas, and uninformed. The oldest-ever-person lived 122 years, she died 22 years ago. The next oldest lived 119 years and died 24 years ago. Recent deaths (2017-2018) of long-lived people were in the 116-117 year ballpark. If the idea of us being able to raise life expectancy by magic or medicine was true, we should have seen someone beating the 122 year record during the last quarter-century. That didn't happen. Also, consider that the penny dreadful of people generally living shorter lives in the old days is simply untrue. What's true is that if someone chopped off your head or thrust a spear in your side, or if you died from plague or dysenteria, then truly your life expectancy wasn't so awesome. However, if you were left alone to live a peaceful life, you could very well get old a thousand or two thousand years ago. No problem. Socrates was murdered tried and executed at the age of 71, in perfect health. Ramesses II lived, if archeologists translated correctly, 90 years. That was 3400 years ago. There's a good chance you die at or after birth (or while delivering), medicine can help with that. That's why the average has gone up so drastically, too. Obviously, if half of the population doesn't die during the first few years, then the average lifespan gets longer. But in reality, this doesn't mean anything. There's a chance you die from a variety of diseases, medicine can sometimes help with that. Alright. If you get through that unharmed, you'll live 100-120 years, and that's the end, do what you will. There's strong indicators besides the verifiable fact that nobody actually manages to get older (despite there being no urgent reason to die). For example, the delicate balance between proto-oncogenes and tumor-suppresors. Which, if you think about it, makes the "we will be able to cure cancer" statement a really funny joke (funny because its naivety). Nature doesn't work as simple as "press button here". Yes, we can do kinda awesome things that nobody could imagine 30 years ago. But whatever it is, it's still just a crude hammer, and Nature is a fine clockwork (and we don't fully understand the construction drawing). Our entire life is about wandering on a narrow ledge, and the abyss is both to the left and to the right. Go too far to the right and your cells just die (this has been demonstrated in vivo using p53 on mice). Go too far to the left, and you get an entirely different problem (kinda obvious). There's that other magic cure for everything called stem cells. Except they're no cure for everything either. There's a limit to how often you can make them reproduce, and there's a limit to how fault-tolerant their DNA is over a century. Oh right, there's CRISPR/Cas9 to solve all our problems. Please. Don't. No, sorry. No magical life extension any time soon. That's just not realistic, even less so from something as crude as replacing a few organs. If nothing else, your senescent brain cells will eventually just die, and there you go, goodbye. [Answer] You mentioned in a comment that you meant current technology, so, definitely no. We just don't have the organs yet. Artificial hearts exist. They can work for years without a hiccup, but they can also fail catastrophically at any moment. Many do. I admittedly didn't do any research, but I'm very confident that their failure rate is much worse than that of the average natural heart. Charging is also an issue. The closest we have to artificial kidneys are those huge dialysis machines which obviously could not be implanted in an elephant, much less in a person. To my knowledge, there's no current technology able to replace lungs, liver or intestines, except transplanting a natural one, which has obvious scale limitations. [Answer] Considering the comment by the OP, the question is: > > Would replacing healthy organs with replacement organs be beneficial, using current technology. > > > If you're looking for a science based answer, the answer is unequivocally no. No current mechanical organ replacement gives as much of survival benefit as an allotransplant (organ transplant from another human). These devices are at best a bridge to transplant in patients who are healthy enough to get a new human organ. Additionally, allotransplant is unequivocally worse than keeping your own healthy organ. It is even worse than keeping a not particularly healthy, but not quite yet failing organ. As a rule, we try to manage unhealthy organs medically for as long as possible before even considering transplant. The major problems here are rejection and vascular events, or the problems that result from treatment of those problems, bleeding and infection. Organ failure (of the transplanted organ) is an issue as well. A new organ can feel like a new lease on life to someone who, for example, has been in stage IV heart failure, but it comes with major challenges. To use the metaphor a few other answers have used, OEM parts are best (human organs), but a replacement part of any kind is not an upgrade unless the original part has failed. You can read about this in Schwartz's Principles of Surgery, Chapter 11, if you'd like to learn more. [Answer] Assuming the artificial organs work just as well as current one's but eliminate the organ's failure, a definite yes. It wont expand it indefinitely though. * With this much organs being replaced you reduce the amount of potential cancers. * Any cancers that do develop are less likely capable of destroying the artificial organs by growing through it (which is why cancer is so dangerous, it causes organ failure. Just having cancer will not kill you). And if they are capable the cancer needs more time to kill off the organ. This leaves basically two things to kill you: deterioration of the brain, which often takes longer than most causes of death so you already have a longer lifespan, and deterioration of your bloodvessles and supply which eventually causes the artificial organs and brain to die off. Potentially also failure of your immune system depending on if it's artificial or not. Regardless, the average lifespan definitely increases! Some statistics can be found here: <https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death> Interesting here is that you actually see the exact effects of your proposal reflected in the changes in death causes. As medicine advances and things that would cause death before become cureable, allowing people to live long enough to die of something else. This allows cancer, alzheimers and other diseases to get more deathcauses. Its almost perfectly with your scenario except the medical care doesnt come from artificial organs. [Answer] Yes, to some extent. The benefit of replacing organs with artificial ones is that humans become like cars, and medicine becomes like car repair. When something breaks, you find the broken part and replace it. Currently, people die from organ failure. That wouldn't happen. Liver cirrhosis: wouldn't happen. Early-stage pancreatic cancer: wouldn't happen. Type 1 diabetes, most heart conditions, ruptured organs, emphysema, arthritis and blindness would all be curable if we had the option to replace damaged or defective organs. You could replace entire bones at a time to reduce the effects of osteoporosis. However, it wouldn't make us immune to everything. I'm drawing the line here at the brain, since replacing the brain but preserving your consciousness and memories is far beyond the technology we're discussing here. 10 percent of Americans over 65 are afflicted with Alzheimer's disease, which affects the brain. Alzheimer's is the 6th leading cause of death in the US. It wouldn't be solved at all by this new form of medicine. There's also the matter of cellular senescence. When cells divide, small amounts of their DNA are lost. This results in the cellular DNA shortening slightly with every division. To protect against adverse effects from this, the ends of your chromosomes are tipped with sections of random DNA called telomeres. This provides a buffer of DNA that can be safely deleted without damaging your genes. However, as you age, the telomere shortens, and eventually, the functional DNA in your cells is damaged, causing the cell to stop working and just sit around doing nothing, taking up energy. The more of these 'senescent' cells you have, the less efficient your body is, and the more likely you are to develop chronic problems. Replacing individual organs would only help with this to some extent, since we are more than just a collection of parts: every cell has its own complexities. Of course, metastatic cancer would be completely unaffected by this treatment. So while organ replacement would make several life-threatening ailments trivial matters, it wouldn't address other, equally deadly problems. Statistically, this would increase life expectancy by a decade or two, maybe, but it wouldn't halt aging or remove the medical problems associated with it. [Answer] TL;DR Life Span will Increase. How much is a statistical calculation someone could do, but a other quest to your question: How many parts of the human will be replaced with artificial parts and the "Person" will be still called human? If everything is Replaced but the Brain, couldn't you just put the Brain into a Vessel for it. So just removing the Brain from the Body. One thing you still have, and it would be the deadliest killer is Brain Cancer. Other things would be more like Accidents or murder. And then: why do so many people die before there "best by date"? If you have the technology to replace body parts with artificial ones (that are working without problems) then you have also the technology to repair the damage sickness could do OR replace it when its not possible. And even today body parts are replaces by artificial and ones from other Humans. They are expanding the lifetime of that human (from hours/day/months to years/.. most of the time) so why shouldn't it be if the entire body could be replaced. [Answer] # Of course, but not much I don't have any place to quote it, but, it's very common that the common reasons for dying of old age are basically acumulative damage done in any part of your body due to its usage. Some examples are: * [Cancer](https://en.wikipedia.org/wiki/Cancer#Causes). Each cell division slightly increases the risk of cancer due to telomeres shrinking, replacing an organ (and its cells) will "reset" the chancer factor due to age in that specific organ. > > Common environmental factors that contribute to cancer death include tobacco (25–30%), diet and obesity (30–35%), infections (15–20%), radiation (both ionizing and non-ionizing, up to 10%), stress, lack of physical activity and pollution > > > * Cardiac diseases, a heart is like a machine, it gets rusty over time. A heart in any animals has between 1 to 1.5 billions of beats in a whole lifetime. Just check in Google, like [here](https://www.sciencealert.com/relationship-between-heart-beat-and-life-expectancy). Humans are the only race who can have a bit more than 2 billion due to medicine. After that usage (i.e: when you age), statistically speaking you are dead, the chances of dying for a [cardiac arrest](https://en.wikipedia.org/wiki/Cardiac_arrest) are very high. Imagine if you could replace it after reaching the limit like you replace an old car with too many miles/kilometers. * Well, basically any disease related to old age. Replacing dysfunctional/old organ will obviously increase the lifespan due to a decrease in death risk for those diseases. Sadly, there are three problems: * Philosophical: Did you know what is the [Ship of Tesseus](https://en.wikipedia.org/wiki/Ship_of_Theseus)? Is a philosophical paradox, basically is, if you replace all your body parts when you stop being "you"?. Lucky, you don't replace your brain, no problem. * [Orgain Rejection](https://en.wikipedia.org/wiki/Transplant_rejection): With our current technological level, is very difficult to replace an organ, and there is always a chance of failure or refusal from our body. * [Brain Damages](https://en.wikipedia.org/wiki/Brain_damage): You said we can't replace our brains, that means that one part of our body (curiously one with the worst self-healing properties) can't be replaced and will always accumulate damage. At some point, it will stop working... and so we would die. That is why I can say it will increase our lifespan, but not much. Our brain is very close to the limit. Have you heard for example about [alzheimer](https://en.wikipedia.org/wiki/Alzheimer%27s_disease)? It's is a mental disease caused by the brain due to old age, one every 17 people of +65 years has it, and it can be deadly. If a cardiac arrest didn't kill us before (due to replacement) a brain disease will do it not much after. [Answer] Absolutely Not Anyone who says otherwise has never spoken with or worked with anyone who has undergone even hip replacement — much less something more dramatic like heart replacement. The human body is amazing. Self-healing, self-protecting, flexible to an amazing degree; its weaknesses are far, far, far, outweighed by its incredible capacity. Walking away from that for the sake of something that doesn't work as well just because (e.g.) it's made out of plastic that we think will sit in a landfill for a thousand years is breathtakingly short-sighted. Let's begin with a quote from H.G. Wells (and I'll be honest, I don't know if this is actually a quote by H.G. or a paraphrase used in the popular Tom Cruise movie... but it's cool — as almost everything intoned by Morgan Freeman is — so we'll use it): > > By the toll of a billion deaths man has bought his birthright of the earth, and it is his against all comers.... > > > Compare this to the artificial anythings which, at best, have only experienced a couple of thousand years of development. Artificial replacements are good ways to save life, but they're limited You didn't mention whether or not quality of life was an issue. Living for 200 years hobbling around on a peg leg with an artificial heart that wouldn't let you get a good run at the neighbor's dog may satisfy your question — but what would be the point? We can keep the body alive fundamentally indefinitely (think, "brain dead"), but there's no quality of life — you're just lying there being a vegetable. But let's ignore that and focus only on the idea of extending lifespan. I've known dozens of people with artificial knees and hips. They were usually replaced sometime in their 60s or 70s — meaning the first set survived 60 or 70 years — and are in need of a second replacement within 10-15 years. It's not usually the joint itself that needs replacing — it's the surrounding tissue and bone that wasn't designed to accommodate the replacement that's the problem. Tissue and bone that keeps on growing as if the original were there — but it's not. Artificial hearts have improved in technology considerably over the last 20 years, but they still have problems with infection and bleeding because they are not flesh. They do not enjoy millions of years of adaptation against all of the problems that can beset the human body and, when push comes to shove, you're connecting fleshy veins and arteries to something that isn't. That connection will always be a weak point. So, too, will the control connections that drive the heart to greater or lesser pressure to meet the body's needs. The assumption that the natural body is more prone to failure is fundamentally erroneous Statistically, healthy people with artificial replacements have more problems compared to healthy people who do not have artificial replacements. Note that condition: healthy people. People who need replacements are not healthy by definition. No doctor would agree that an artificial anything is a better replacement than nature's original — an original that has, by the toll of a billion deaths, earned the right to be where it is. Humanity is a long, long way away from developing better replacements than nature's originals. Therefore, no, people would not on average live longer lives if we replaced everything we could with artificial replacements. And they certainly wouldn't live better lives. [Answer] No. It would shorten life. Current technology isn't even available for many organs. Insulin pumps are a poor substitute for a working pancreas. There is nothing even on the horizon for an artificial liver or lung. ### Plausible alternatives There's work being done to grow organs in pigs that are rejection free. Pigs internally are very similar to people. So natural transplants could work this way. This would not be a particular improvement on what you have, but could extend your life. There are potential life prolonging drugs that work in various ways. Nanotech or artificial life may produce something like a rotifer that could clean out your arteries. Think microscopic roto-rooters. (What could go wrong? His rotorooters didn't recognise the artery wall and turned him into swiss cheese...) [Answer] This may seem obvious but... It depends on the quality and type of the artificial organ. For example, the valveless heart (a real thing, but only moderately well tested) functions by pumping blood via water screws instead of a traditional pumping action (interestingly, this results in the complete lack of a pulse). However, due to it being a steady calm pressure instead of constant on-off, it's expected to do a lot less wear and tear and increase longevity and quality of life. Further, if made from sturdy materials, it could easily outlast the person it's in while also removing the number one cause of death: Heart Failure. However, a traditional mechanical heart replacement is only good for a fairly short timeframe due to human-designed pumps being one of our most error prone inventions (unlike waterscrews, which are among our most reliable). [Answer] Given current medical technology: Absolutely not. To the best of my knowledge, all artificial organs available today are seriously inferior to the natural organs. They don't heal themselves if damaged, they don't have the range and capacity of natural organs, etc. It doesn't take great imagination to speculate that as medical technology progresses, artificial organs will get better and better. Will they eventually be better than the natural ones? Maybe someday. Realistically I think that's a long way off if it happens at all, but who knows? There could be a breakthrough tomorrow. [Answer] I'm going to say yes, but not for the reason that you're thinking. As Alex2006's answer explains, the leading causes of death in old age are not related to organ failure in the list of organs you're proposing to replace. It is unlikely to increase the maximum age to which we live, or meaningfully extend the life of otherwise healthy individuals. However, life expectancy is an average. It is calculated from the expected and experienced age of death over the whole population, and is thus strongly affected by things like infant and child mortality. When someone mentions that the life expectancy in the paleolithic was 35, this does not mean that most people tend to die around that age. Most people who lived past childhood lived to a reasonable age, but infant mortality was high enough to skew the average down to 35. This is still the case in many countries around the world. Some of the [leading causes of infant mortality](https://en.wikipedia.org/wiki/Infant_mortality) are related to organ failure. Congenital defects in organs, premature birth and infection are all leading causes of infant mortality, some of which we don't yet have effective medical treatments for in the first world, let alone the third. If your replacement organs can effectively replace a congenitally defective heart, or poorly-formed/infected lungs in an infant then they will likely have a significant effect on the life expectancy of a country, depending on its level of development and the access to your treatment. tl;dr Sophisticated artificial organs wouldn't increase the life expectancy by making the old live longer, but they would by giving the young a chance to live at all. [Answer] [Humans currently have a maximum age of around 121 years](https://theconversation.com/lust-for-life-breaking-the-120-year-barrier-in-human-ageing-14911) , regardless of non-genome based treatements, because of [Senescence](https://en.wikipedia.org/wiki/Senescence) More precisely because of the [Hayflick Limit](https://en.wikipedia.org/wiki/Hayflick_limit). This is a [DNA based limitation](https://www.ncbi.nlm.nih.gov/books/NBK10041/) on our species' age. It marks roughly the period around which human DNA will begin to break down, and Cell Replicaiton/Maintenance will stop working correctly. After this begins, death is inevitable. The 120s therefore marks a ceiling on maximum human life expectancy. I make this point, because any treatment that does not directly address the problem of Senescence will eventually hit this ceiling, which will then be the bottleneck. So even if we did everything possible to prevent humans from dying, from disease or organ failure, humans life expectancy would still only be around 120 years. So no 1000 year old humans with out gene therapy. ]
[Question] [ My story takes place in a post-apocalyptic world where there are no humans. On the island of Manhattan, which has been abandoned for a long time, there are communities of animals with human-level intelligence. This includes pigeons. Physically, these birds appear to be the same New York pigeons we see today eating garbage and basically making a mess of things. However, by the time the story takes place, they have developed a complex multi-party democracy that, by coincidence, runs more or less along Westminster system lines. These are urbane and cultured pigeons, with a rich tradition of literature, philosophy, mathematics and, their specialty, diplomacy. Recognizing that their battle prowess is, frankly, pathetic, the pigeons specialize in manipulation, subterfuge and information control. They can't win a straight fight against their enemies, so they have gotten very good at getting their enemies to fight each other. Here's the issue: Why do these pigeons stay in Manhattan? The other animals, that's easy enough to handwave, as the bridges and tunnels are destroyed and the rivers are now plagued with alligators. But that should prove no issue to the pigeons, who can just fly over them. And, indeed, this could be seen as the smartest thing for them to do. On the island they have to deal with other intelligent animal communities. Away from it, they're the smartest things around. But I don't want that to happen. I want the story to remain in Manhattan (perhaps the greater NYC area at most). So why in the world don't the pigeons leave? While I am prepared to use a science/tech explanation as a last resort (e.g. there's a special enzyme only found in foods there, intelligent animals have nanobots that can't operate off island, engineered retrovirus needs other animals to remain active, etc.) I'd ideally prefer to use a more social or political reason. An explanation for why colonization beyond the island just isn't practical, as reasoned by the pigeon government itself. But then, what would this explanation be? Why do these pigeons stay in Manhattan? EDIT: All the answers so far point to a solution that I feel silly not considering before: they simply don't want to. I mean, similar to that one answer, I'm someone who doesn't really like leaving the city that much, and as much as city living can be a pain, moving to a desolate countryside full of dangerous animals appeals not at all to me--I mean, if nothing else, where would I get my lox bagels? Why wouldn't it be the same for birds that think like humans? And I'm someone WITH opposable thumbs. It would be even rougher for a bird, or even a flock of birds especially when, as pointed out, your only real advantage is your intelligence and communication skills. Out in the wild, there's no one to negotiate with, and whatever animal you meet is more likely to care about eating you than hammering out a multilateral trade agreement. Maybe there were a few tries, but they all turned out like Roanoke and eventually the pigeons decided it wasn't worth it. [Answer] To these animals, Manhattan is the civilized world. Anywhere else is just lawless wilderness inhabited by feral creatures that will prey on each other without a second thought. To move away from there would be like an average urban dweller to move to deep in the Amazon. The isle does not keep them in, it keeps the dangerous wilderness out, allowing for the civilization to thrive. Even if you have a few intelligent predators, most would rather not venture outside due to the much more dangerous and territorial uncivilized predators. Perhaps the immediate surroundings of the isle are like the wild west, a dangerous and unconquered land inhabited by a few madlads. But the connection to the rest of the country will make successful colonization impossible due to the flow of dangerous animals migrating to the area. [Answer] Because, like Dr Doolittle, they can talk to the animals If these pigeons are physically the same as their ancestors today, there are a whole lot of things they can't do. They can't develop a tool-using society because they lack opposable thumbs or an acceptable substitute. They aren't strong enough to lift heavy things and their body shape plus limits on airspace mean they can't effectively cooperate to lift heavy things. The only thing they have going for them is their intelligence and communication skills. Outside Manhattan their intelligence and communication skills are of limited use - they can talk and philosophise with each other, but it's not going to be of a huge benefit to them. On Manhattan, however, they can communicate with other intelligent animals that can do things the pigeons are physically incapable of. (While it is not stated in the question that they can communicate with other animals, if they put their minds to it I'm certain they can create Pigeon English as a common language for the various species on Manhattan. Sorry about the pun.) If they can trade their special services - for example carrying messages and aerial recon - with a ground-bound species that is stronger then they can get more done. If they can befriend apes or at worst monkeys who can use tools then even better. In short, if your primary advantage is the ability to talk your way out of trouble then you are best off in the vicinity of those that will listen. An intelligent eagle in Manhattan may be hard to convince to pass up an easy meal, but an eagle anywhere else can't be negotiated with at all. [Answer] ## The rest of the continent is ruled by crows Corvids are notoriously smart, with some species already having intelligence on par with apes, capable of manufacturing tools, and understanding physical laws. Now imagine if the aftermath of nuclear war (or whatever that had caused the extinction of hairless apes) had granted sapience to pigeons, of all birds, what this would entail for birds that were already much smarter than a piece of rock? So pigeons don't want to leave the island, because that's the conditions of the treaty they established with the corvids - they don't try to mess with their society, and in turn, crows leave them alone as well. [Answer] I have met people in Manhattan who haven't left Manhattan in 20+ years. Perhaps your pigeons have the same mindset. You know the one. I could see this being real funny in a story. "Ew, you crossed the bridge??" [Answer] They are racist bigots. Outside of Manhattan there are other pigeons. Those pigeons. Not that smart. Not smart at all. Really just animals. Now don't get me wrong - the pigeons out there are easy on the eye and some have nice voices. They are fine with their own kind. But you let one of those green-necked Lotharios get at your daughter and next thing your know you have grandkids who can't count. You go out for a little fun in the country with a cute rock dove and a year later some halfbreed shows up that knows you are its dad. No, city pigeons need to be with city pigeons. There is too much risk in mixing with the outsiders. [Answer] As a last ditch science option (with some political angle), at one point in time they couldn't navigate outside of Manhattan. The calamity that killed off the humans disrupted the Earth's magnetic field, it didn't disappear it just got alot more chaotic. As some birds have been found to sense magnetic fields, I will assume that pigeons can as well. Thus when ever some adventurous pigeon tried to leave they get extremely dis-orientated and to others they appear to go "mad", and lose any ability to navigate and no self-respecting pigeon isn't able to navigate. Thus those that tried to leave (but cam back) become outcasts. The pigeon-government has realized what happens and starts setting up children's stories about the big bad that happens when you leave. Pigeons are threaten with banishment for breaking laws. Thus over time your pigeons will end up fearing any attempts to leave, lest they become "mad" and lose their minds. Whether the magnetic field still cause problems no one knows, as no one dares find out. [Answer] Q: They have developed a complex multi-party democracy that, by coincidence, runs more or less along Westminster system lines Political affiliation and lessons from the past Earth was once human. Current pigeons ancestors thrived in human cities, they were influenced by humans, human culture and human remains. Their system is in fact human. There are two important players in the pigeon political universe: one of these hates these non-pigeon human influences and wants to ignore human culture alltogether. They prefer to talk about NY pigeon independence, pigeon supremacy over other animals, wanting to conquer the world (pigeonize, spread pigeonism) The other political group, the largest group, still adheres to human habits and parts of human culture. They keep a strong tradition of being peaceful, because the pigeon (dove) had always been a symbol of peace in human culture, and also, wise old pigeons always warned for human error and human inflicted disaster. Don't repeat the same mistakes. The pigeonist pigeons have not been elected into the government since NY parliament exists. These mainly male chauvinist pigeons are a loud group, but they have been a minority for 160 years now, since the Crows cleansing debacle and the events that followed this most unfortunate episode in the history of NY pigeon rule. [Answer] Same reason my intelligent dolphins haven't: they're not interested. Taking over the world is a lot of hard work, they'd rather just hang out and have fun. And yes, that's a very Hitchhiker's Guide to the Galaxy style answer and may not be appropriate to your context :) But seriously, whether an intelligent species has the potential to take over depends on more than just their level of intelligence. An intelligent molusc for example would lack the capability to manipulate its environment for example. An intelligent bird may be severely handicapped by its inability to use tools effectively as it has no arms (yes, it could hop about on one leg and use the other, or hold one in its beak, as some birds have found out, but we're talking efficient here, not capable as such). Or as the Guide puts it, they may simply not be interested as long as there's free food available. [Answer] Let's not forget basic biology here. They are [Rock Pigeons](https://en.wikipedia.org/wiki/Rock_dove) who have been adapted to nesting in rocky crevices. The cityscape if simply full of rock crevices. Yeah, they can talk and chat and think, but they still gotta go back to the nest. (The similarities between caves and human dwellings are also compelling!) This basic biological adaptation keeps them in the city, simply because there are no viable nesting sites outside the city. So what keeps them in Manhattan? Simple: the other parts of the city are effectively different countries. Maybe those countries are ruled by other pigeons, maybe other creatures (like those [corvids](https://en.wikipedia.org/wiki/Corvidae) or worse, those [falcons](https://en.wikipedia.org/wiki/Peregrine_falcon)), but you the cultural and political divisions are just so that outside of Manhattan is another country. [Answer] The ruling class discourage it In order to maintain control over the pigeon masses the ruling politicians discourage migration and strip the citizenship of any who leave, preventing them from returning. A real world parallel might be Western citizens who traveled to the Middle East to join ISIS. Their citizenship's were sometimes completely stripped and they face harsh sanctions if they were to return to their countries of origin. [Answer] # Population Pressure It's quite simple. Much of the push to settle areas is due to population pressure. The pigeons simply haven't filled the island yet, and due to unknown dangers, the few who have gone beyond the island haven't returned. I'm not familiar with how prolific pigeons are, but the same mutations that gave them intelligence (or related ones) may also have reduced their fertility rates, if that's an issue. [Answer] # Because they are [homing pigeons](https://en.wikipedia.org/wiki/Homing_pigeon) Pigeons have a remarkable sense of navigation, and will return to their nest, even at distances of hundreds of miles. Humans have been taking advantage of this ability for thousands of years for communication and sport. So even if the pigeons temporarily leave the city, their instincts bring them back home. ]
[Question] [ When worldbuilding, what elements can be introduced that can justify the conquest or overtaking of a technologically superior species by one that is not as advanced, or much weaker. [Answer] Oh so many things, it's a great open ended question. Answering assuming one nation is more technologically advanced and economically powerful than the other but is conquered by the less advanced one. 1. Just because you have technology and money doesn't mean you are using it on your military Different cultures focus different amounts of tech, wealth, effort on military power than others. Given time nations can pivot their effort and improve their militaries, but this can take years. A sudden war from an inferior enemy can catch you without any standing army. After WWI the US military shrunk to almost nothing. Even though the US had advanced tech, large population and lots of industrial capability it took years of lend-lease production and recruiting ramp up to get the US military on par with other powers when the second world war started. 2. Some technology differences don't really impact combat The difference between a soldier from the year 1200BC and a soldier from the year 800AD is not major. One has bronze, the other iron - maybe a 50% advantage but not a 10 to 1 advantage. At that point the ability to organize and motivate a larger army is more important. 3. Desperation, and complacency Many times in history we see a nation make changes when they are desperate and have to, and remain complacent whenever they have the chance. Japan retained its medieval technology level for hundreds of years but was forced out of isolationism at gunboat point. It then went though the almost miraculous Meji restoration modernizing a nation from the medieval era to a WWI era military capable of defeating a major power in 1 generation. In the ashes of WWI the victors assumed the next war would be the same and rested on their laurels, they neglected understanding the new tactics which would come with tanks and airpower. The defeated nations (Germany and Russia) needed to improve so they experimented with new weapons and would have the edge in the coming war. Nations that don't have to fight a war may resist making changes they have to make to fight a war, and may resist them for a long time. Put it another way: fighting to the death means you might die, so you don't do that unless it's for something really important. 4. Do the people care if they are conquered There is a joke (I admit not a great joke) that China conquered an empire by being conquered. There are several Chinese dynasties that start with a neighboring warlord or tribe leader (with less advanced technology) invading and conquering China. The Chinese bureaucracy and government system was so good that the incoming warlord would just use it and become emperor in China as well as their home kingdom. Gradually the emperor's home kingdom is put under the same government system and is absorbed into China, and thus China grew. It was bad for the former emperor and his soldiers but for the average peasant it mostly just changed who they were paying taxes to. Before the advent of nationalism in the 1800's most people were not that loyal to their country let alone being willing to die for it. Maybe the citizens of "defeated" nation don't care about which emperor is in the palace, and just change the faces printed on the currency and absorb their conquerors. [Answer] Have you never heard of the barbaric invasions leading to the collapse of the Roman Empire? The Romans were able to build structures like the Colosseum, the Pantheon and all the aqueducts to supply their cities with water, yet they were defeated by gents whose best building was a straw covered hut. How did that happen? Weak central power for the amount of territory to control, economical crisis and some well timed plagues. [Answer] ### So many options * High morale defeats low morale + If your troops dont want to fight, they're not going to win. If the war is unpopular at home, and the troops are spat on as killers when they come home for a break, they're not going to be an effective fighting force. Think Vietnam war. Huge oversimplification but were the USA motivated on the home front at the same level as they were in ww2 Vietnam would be a us territory now. They werent motivated. Instead south Vietnam got overrun and captures. * Weight of numbers + A thousand guys with spears could take out a few guys with a super weapon. Look at the StarGate original movie final battle, as poor villagers rush Ras guards despite their superior staff ray guns. * Element of surprise - or underestimating + Look at tet offensive. A "primitive" vietnamese army launched a sophisticated attack on the us military. It was beginning of the end and ended up capturing Saigon. * Supply lines + When Germany invaded Soviet Union the tech balance was in favour of the germans. They stretched their supply lines and eventually starve and froze to death. 5 years later half of Germany is under Soviet occupation. [Answer] War and conquest, according to Von Clausewitz, is about politics. Political sophistication (or ossification) is not particularly correlated to technology. War and conquest, according to Jomini, is about proper application of the principles of objective, offensive, mass, economy of force, maneuver, unity of command, security, surprise, and simplicity. Only four of those nine principles are markedly improved by technology. You don't need superior technology to recruit allies, or to drive a political wedge to split the enemy alliance. You don't need superior technology to coax the enemy to squander their strength and resources seizing objectives that turn out to be worthless. You don't need superior technology to sow fear and terror in the enemy population, nor to bribe (or daunt) the enemy leaders. [Answer] ## Technologically Advanced is not the same things as Militarily Advanced Because the OP mentions different species, not just different cultures Humans for example have evolved through generation after generation of constant warfare to constantly think about and innovate new ways of killing. We invent a knife: we start making swords. We invent a firecracker: we start making guns. We split an atom: we start making nukes. Basically, if we invent something, it is in our nature to ask how we can turn that invention into a weapon. It only take a cursory glance at our entertainment industry to see that by the time a human child reaches adulthood, he's already experienced thousands of hours of simulated violence preparing him for real world conflicts. But what if your advanced species does not think like us? Maybe they did not evolve on a world where war was a thing; so, while they know that their anti-matter reactors, and FTL drives are potentially dangerous, it's just not in their nature to ask themselves how to turn those things into weapons. Now let's say that such an advanced species were to encounter a less advanced human like species, they would only be learning what a "gun" is for the first time when one start shooting them. They might try weaponizing their dangerous technologies, but the very idea of war is just so darn scary and repulsive to them that they can't find any of their own people willing to go to war... and when they do, they are so psychologically un-cut out for it that any armies they do assemble fall into chaos at the first signs of danger. In the end, the advanced species can not figure out how fight a war, but they can figure out that if they just do what the violent species asks them to do, that they will stop killing them. This comes as a huge relief to them when they realize that being conquered is an option. ... but if both species are similarly warlike by nature Even with more or less equal military instincts, their cultures may not put the same emphasis on military technology. This has happened a few times throughout history. One example was the conquest of the Western Roman Empire. The Germans were much less advanced than Romans when it came to architecture, agriculture, logistics, luxury goods, etc. But when it came down to the basics of things like weapons and armor, the Germanic peoples were constantly innovating in these areas; so, they often enjoyed the technological advantage on the battlefield, even if their civil technologies were not as good. So yes, Rome could generally be described as more advanced, but their aqueducts and amphitheaters could not protect them from being conquered by superior military technology. ## As for when Military Technology is Inferior This is a much more rare case, but it does happen. When one group of people are less militarily advanced, they can often resist being conquered using Guerrilla Warfare, but this does not really allow them to exert their control over another nation in most cases. Conquest means that you need to be present and accessible to rule which is the antithesis of Guerilla Warfare; so, when a technologically inferior army outright defeats a superior one it typically follows some combination of the following 3 models: 1. The inferior nation has superiority of numbers. The Battle of Isandlwana is a good example of this where the Zulu nation sent 20,000 men armed with stone-age weapons against about 1,800 British soldiers armed with rifles. The Zulu's numerical advantage was enough that they could close into melee range before the British could fire enough rounds to stop the charge. WWII is another good example. The most of the allies had distinctly inferior military technology to Germany, but between the Battle of the Bulge and Operation Barbarossa, the allies had about a 6-1 numerical advantage and conquered Nazi Germany. 2. The inferior nation is quick to adopt the technologies of those they fight. Rome was bad at innovating their own military technologies as I've already pointed out, but they were very good at recognizing and copying the military technologies of others. So, while there were many wars that started off looking very bad for Rome, the Romans would just adopt whatever weapons and strategies that they were losing to allowing their superior numbers and logistics to decide the final outcome of many of their conflicts. 3. The inferior nation chooses a battlefield or strategy which favors the technology that they do have. A good example of this would be the first Hebrew conquest of Israel. The native Philistines fought in the Mycenaean Greek tradition of Phalanxes armed with bronze scale or plate armor, long spears and heavy shields supported by a large number of chariots, while the Hebrews were mostly armed with wicker shields, no armor, and short weapons like clubs and Khopeshes after the Egyption military tradition and are believed to be lacking in chariots or mounted warriors in general. Although other wars showed without a doubt the superiority of phalanx infantry, and the value of mobility offered by chariots, the Hebrews were good at luring the Philistines into terrain that was too rough to maneuver a phalanx or chariots in, and were thus able to win a number of key battles and conquer "the promised land" despite significantly inferior military gear. [Answer] [Arthur C. Clarke’s “Superiority”](http://www.mayofamily.com/RLM/txt_Clarke_Superiority.html) is a short story [which explores this idea](https://en.wikipedia.org/wiki/Superiority_(short_story)): > > "Superiority" is a science fiction short story by British writer Arthur C. Clarke, first published in 1951. It depicts an arms race during an interstellar war. It shows the side which is more technologically advanced being defeated, despite its apparent superiority, because of its willingness to discard old technology without having fully perfected the new. Meanwhile, the enemy steadily built up a far larger arsenal of weapons that while more primitive were also more reliable. > > > [Answer] I note that "conquer" is ambiguous. One culture can overrun another and even install a member of its culture as the monarch, without being able to hold onto it for a long time. But the main way this works is social problems on the part of the conquered. They are many, not united, generally engaging in in-fighting. This means that the conquerors can take them piece by piece. Parts of the conquered may even surrender without fighting to avoid their culturally internal foes. Others may betray their foes to the conquerors because they think their position as conquered will be superior to their position pre-conquest. Many will regard the conquest of those of other factions/regions as not their problem. This works for the initial conquest, but it does lead to the problem that it's hard to hold. The culture will not start working as a unified and harmonious whole merely because the other side won. [Answer] Sometimes people become so enamored with technologic advances that they forget the simpler ones even exist. One Stargate SG1 antagonist was the [Replicators](https://stargate.fandom.com/wiki/Replicator), technological beings that could replicate themselves. The Asgard (a technologically advanced race with FTL travel and incredible weaponry), were struggling against them until the SG1 team brought their "primitive" weapons... basic military firearms. The bullets could shatter their bodies and were not electronic in any form. It proved to be devastating to them. [Answer] The technologically inferior people has a super seductive, infectious culture. [![KFC Japan](https://i.stack.imgur.com/9405X.jpg)](https://i.stack.imgur.com/9405X.jpg) <https://www.cnn.com/travel/article/kfc-christmas-tradition-japan/index.html> Your tech inferiors have the coolest clothes. The ladies do their hair in amazing ways. Their popular music makes you dance, then cry, then dance and cry. Their food is so delicious and addictive and their cultural icons croon to the Jungian archetypes in every soul. They have a religion that is so appealing it is no contest with what passed in the tech superior country for religion. Yes they are barbarians, these inferiors. Their factories are inefficient and clunky. Their medicine is out of date. But they are so cool that everyone wants to have them around! Everyone wants to be like them. Their culture moves in, with their language right behind, hybridizing with the native language. Within a couple of generations, the citizens of the technologically superior nation are indistinguishable from those of the inferior nation. Does that count as "overtaking"? One example I can think of is infectious American culture. [Hellenism](https://en.wikipedia.org/wiki/Hellenistic_period) may be similar - the spread of Greek culture thru the ancient world not via conquest but because of the intrinsic appeal of that culture. Maybe @AlexP will weigh on the accuracy of that juxtaposition. [Answer] What you can do is have a large faction in the technologically inferior civilization request to join the more advance civilization and have the more advance civilization come to help this faction 'liberate' the country. The USSR justified many of their invasions this way since many of the nations they entered had a Communist Party that specifically requested the aid of the Soviet Union like how East Germany formed after the fall of the Nazi Germany during Soviet occupation, partly because the newly reformed German Communist Party asked for the USSR's continued aid in establishing [a socialist republic](https://www.britannica.com/place/Germany/The-era-of-partition#ref297750). So similarly, have a major political party of the less technological nation request help from the more technological nation to build a more stable nation, making the situation less of an outright 'conquering', legally speaking, and more like assisting political allies. [Answer] > > what elements can be introduced that can justify the conquest or > overtaking of a technologically superior species by one that is not as > advance > > > Make the advanced species human and the less advanced a disease or parasite. At all times in history humans have been more advanced than bacteria or mosquitoes and yet for thousands of years we had no technological way of fighting them. [Answer] There's a really good case study for this in the interactions between the various steppe cultures of northeastern Asia (Xiongnu, Göktürks, Mongols) and the Chinese dynasties to the south. The steppe peoples weren't primitive by any stretch of the imagination, but they did live a much more hand-to-mouth subsistence lifestyle that lacked a lot of the complex technology or social institutions that become more useful when a culture has a sedentary agrarian lifestyle. Nevertheless, the Chinese dynasties were constantly worried about their neighbors to the north and went to war with them and were actually conquered by them several times (the most famous example of which being Genghis Khan). The more advanced culture isn't as militarized China is rather notable among a lot of ancient culture for not having a strong warrior culture or elite warrior class. Rome had the legions, Japan had the samurai, the Greeks had the hoplites, the Aztecs had the various warrior cults, etc. The Chinese...didn't really have any of that. They had a very well-equipped army, but China post-warring states period was a largely Confucian society that valued education, harmony, and learning rather than who can stab whom in the face the best. The ideal Chinese man was seen to be a scholar first, rather than a soldier or a warrior. The Chinese had more advanced weapons in a lot of ways, including repeater crossbows, gunpowder, and complex trebuchets, but they weren't a heavily militarized power with a strong warrior culture that encouraged constant warfare. By contrast, the steppe cultures were heavily militarized. The different tribes were frequently at war with another, and virtually every aspect of steppe life could be translated into warfare in some way. The steppe peoples were good horseback riders, practiced archery in their daily lives for hunting, and even many sports such as [jereed](https://en.wikipedia.org/wiki/Jereed) or [buzkashi](https://en.wikipedia.org/wiki/Buzkashi) have a role in training horsemanship skills that translate well into warfare. Just about every able-bodied steppe man was able to serve as a soldier, and with the greater experience many steppe warlords had from the harsher lifestyle on the plains were able to translate that into greater tactics and gain a strategic advantage over the larger, but less experienced, Chinese armies. The less advanced culture outperforms the more advanced one in some way In terms of technology, the steppe people really only had one thing over the Chinese, their horsemanship, but the thing is they were really, really good at it. China has always had problems with its horses, to the point that one of the few major Chinese expeditions outside China was [to obtain better horses that could be ridden rather than restricted to pulling chariots](https://en.wikipedia.org/wiki/War_of_the_Heavenly_Horses). The steppe peoples were much better riders, which gave them better mobility on the battlefield and allowed them to win many engagements despite being armed with compound bows in contrast to Chinese crossbows. The Chinese really couldn't dictate terms of engagement to the steppe peoples, couldn't really invade their territory (every time they tried the nomads just ran further into the Gobi), and if they broke formation it resulted in the nomads pulling their army apart and winning. In this case being a specialist worked better than being a generalist. Even if your more technologically advanced culture on average has greater technology, the less advanced one might still outperform them in some area because not every culture develops technology in the same way or the same rate. The less advanced culture is able to capture weapons from their more technologically advanced enemies and turn them back on them One of the way the Mongols were able to finally bring down the Jin and Song dynasties were through the adoption of siege warfare techniques such as trebuchets and battering rams. These were mostly designed by Muslim and Chinese engineered captured in west Xia and parts of Jin, not by the Mongols themselves. There isn't a lot of a need to be hauling a catapult around on the Mongolian plains. The Mongols were actually really bad at siege warfare at first, in the first siege of Yinchuan they were completely unable to break through the walls of the city and resorted to trying to divert the Yellow River in an attempt to flood the city, only for it to backfire when the river flooded the Mongol camp. By the end of the war against the Jin they were adept with using siege equipment to the point they were able to crack open even heavily fortified cities. It should be relatively easy for a less advanced group to get their hands on the technology of the more advanced group, through asymmetrical warfare if nothing else. Though, depending on how much of a tech gap there is there might be issues with manufacturing enough to supply all of your troops. For example Native Americans often had issues with getting firearms, especially as they lacked the industrial base to build more guns and ammunition. Ultimately, though, your less advanced culture is going to have to adopt new weapons or upgrade their old ones. Human wave tactics may work in the short term but in the long term you're trading your most plentiful resource (soldiers) away in a bad bargain for better odds. Eventually the high casualty rate will become a problem. The more advanced culture is in political disunity or civil war This is a common trend in history. An empire is in some kind of decline or internal conflict and the resulting disunity allows outside groups to tear it apart. In this case Rome, rather than China, would be the premier example, where neglect of the armies, mismanagement of the economy, overexpansion, and politicians who were more focused on backstabbing each other than preserving the empire (among many other reasons) allowed for outside people to run havoc and carve out their own empires in places like Thrace and the northern Sahara. One big factor that caused problems was that Roman propaganda (and history, since Romans heavily censored their own history) framed non-Romans as backwards idiots, which often led to the Romans thinking the barbarians weren't a threat or weren't politically savvy until it was too late. [Answer] ## Faith It's incredibly what people can do with faith. Vikings for example, they didn't have any fear to die in battle because of their faith in their gods knowing that they would go to Valhalla if they die in battle and feast with the gods. In other hands, some other civilization without faith would be afraid of fighting and dying and leaving family and friends behind. Also, in a war scenario, if you don't have faith in your Commander's plan, then you would probably not be the best soldier you could be if you had faith in the plan. Therefore, a less advanced species with more faith could fight better than the advanced species without any faith. [Answer] As a relatively extreme example, consider the [Great Emu War](https://en.wikipedia.org/wiki/Emu_War). It was fought between soldiers from a top-notch army armed with the latest machine gun technology, and a bunch of flightless birds the size of a mid-size deer. What sounds like it should be a one-sided massacre ended up being an overwhelming failure. The emus were able to render the advanced weapons nearly useless by staying out of range, forcing the attackers to chase them at high speeds over rough terrain (making aiming impossible), splitting into smaller groups (minimizing the number of targets available), and using their agility to make target tracking difficult. This was done by what are frequently referred to as one of the [least intelligent birds](http://www.aviculturalsocietynsw.org/_articles/avian-intelligence.htm) on the planet. They certainly had no concept of war, weapons, or tactics. Yet they were still able to exploit the weaknesses of the "superior" attacker and to force the attacker to fight on their terms. If the emus had become angry enough to counterattack, their vastly superior numbers would likely spell doom for the army regiment (emus have sharp claws and a powerful kick that can kill a human). Other examples include the [Battle of Endor](https://starwars.fandom.com/wiki/Battle_of_Endor), the Martian invasion in [The War of the Worlds](https://en.wikipedia.org/wiki/The_War_of_the_Worlds), or even the [Battle of the Little Bighorn](https://en.wikipedia.org/wiki/Battle_of_the_Little_Bighorn). The common theme is that the technologically-inferior side controls the battle. Local knowledge, brute force, and targeted attacks at the enemy's weak points are the keys to victory. Avoiding or marginalizing their fancy high-tech weaponry is important if you want to live long enough to win. Every weapon has a weakness. It doesn't matter how high tech you are, war is always about turning your strengths against the enemy's weaknesses. As long as your technologically-inferior group is strategy-minded and can dictate the terms of battle, they can overwhelm and defeat a "superior" foe. [Answer] I'd be very wary of looking to fiction for answers to this, since the stories often rely on a heavy swathe of "plot armour" to make sure the results play out the way the author intended. And equally, there's no shortage of military sci-fi (e.g. most of Baen's output) where technological imbalances lead to the more primitive army being fed into a meat grinder. (Though to be fair to David Weber in particular, for all that he's fond of this concept, he does also sometimes look at ways for the "underdog" to compensate...) Fundamentally though, there's a few key factors when a primitive society takes on an advanced society. The first is that an advanced society will generally be allocating more of it's resources to non-military activities. Which includes the percentage of it's population which can be made available for war. The second is that advanced technology - and the training to use it - is expensive. The third is that it depends on the size of the technology delta. The fourth is that (at least in my distinctly amateur opinion), primitive societies can be more willing to risk more, take more dramatic actions and absorb losses. Not least because from a resourcing perspective, the cost of replacing their soldiers is far less than the cost for the advanced society. E.g. it probably costs around $45,000 to get a single US marine trained, equipped and ready to hit the field. And that's before you consider the cost of the logistics required to get said marine to where he needs to be, with the equipment he needs to carry out his orders. And that's still a tiny fraction of how much it costs to train a tank driver or a fighter pilot - or to deliver them and their vehicles to battle. <https://www.nbcnews.com/id/wbna3072945> When all is said and done, technology is essentially a force multiplier. To use a non-military example, one diesel tractor in a field is maybe worth the equivalent of 100 men when it comes to ploughing, etc. But it's probably only worth the equivalent of maybe 4 steam-powered tractors. And in either case, a mechanical tractor costs significantly more, both initially and ongoing. And unlike those 100 men, it can only do a specific set of tasks, it can only be in one place at a time and it requires a lot more maintenance, which needs to be done by skilled mechanics. Who need to have been trained beforehand. Sometimes, the force-multiplier can be high enough to make a difference. Rourke's Drift, where 150 british soldiers fought off several thousand Zulu warriors; a significant factor was that the zulu warriors perceived firearms as a "coward's weapon" and therefore preferred hand-to-hand combat. On the other hand, consider what can happen if the technology delta is smaller, and the "primitive" society is willing to absorb large losses. Because that's essentially what happened with Nazi Germany's assault on Russia (with some assistence from the harsh russian weather). In fact, look at what could happen today if some country decided to equip an army with WW2-era hardware. E.g. the M4 Sherman tank cost approx. $900,000 in 2017 dollars. An M1 Abrams would cost around $9 million, or ten times more. A P40 Warhawk plane would also cost around $900,000 in 2017 dollars, whereas a modern F-35A is somewhere around $80 million, or nearly a hundred times more. And as with the tractor, that's before you consider the time and cost needed to train people to use this newer and far more complex hardware. Then too, your expensive F-35A plane would be able to blow those 100 P40 planes out of the sky, but it can't be everywhere at once. And an M4 Sherman tank would be more than capable of dealing with local armed forces, militia and police forces, especially if embedded with some well trained infantry. Ten of them would pose a major challenge to that Abrams tank; they might struggle to kill it outright, but they'd be able to encircle it and immobilise it. [Answer] Because by not fighting, the Ancients win. The Barbarians win - that's fine. Now they have, at their beck and call the robot army of Ancients, caring for their every whim. It's a useless army if you want to fight a war - but evey Barbarian now lives a life of comfort and ease that they've never imagined prior. Why to to war if you've got everything you want? The Ancients weren't, actually, to be honest, the driving force of the Old Empire. For milenia they were a trap. A target for the younger, hungry races to watch and envy. And each time someone attacked... the attackers won! Only to be cared for, pampered, pacified...turned into pets. Pets of the sentient robot army built to look after, at first, the Anchents. Then ever poor squishy mortal race who attacked. They were just not able to care for themselves - or wise enough to avoid the trap the Ancients fell into themselves. [Answer] If a technologically inferior culture can re-think it's view of the opposing technology, it can see that all machines need to "breath", and hence can be choked. All machines need to see, and therefore can be blinded. etc. If the so-called inferiors can see the fundamentals of what they are looking at, then they can create strategies to defeat them. Imagine shoving a 6 foot piece of rebar down a tanks barrel! [Answer] The advanced species isn't prepared for the war really is. I'm thinking of a theme I've seen more than once in stories: Interstellar travel is a slow business, it takes decades to make a voyage. The advanced species is relying on very old scouting reports. The advanced species has been united under a single world government with something akin to a command economy for a long, long time--their technological progress is now very slow. (Think of China--they thought they were way superior, change was a threat to those in power so they stagnated until they got a very rude awakening--picture that attitude on a planetary scale.) Their scouts have reported a planet at say middle ages tech and 500 years later they go decide to add it as a conquest. They bring weapons suitable for utterly overwhelming such an opponent. As they intend conquest rather than destruction they don't bring more than a few city-killer weapons--they're for shock and awe, not actual combat. They actually run into something like modern-day Earth: The ground forces are along the lines of APCs/light tanks and are total sitting ducks when the Hellfires come in from no apparent enemy. (The Hellfire was originally meant to be guided in by a helicopter hiding behind terrain and only sticking up a targeting pod that is mounted above the rotors, the actual shooters being completely behind terrain and shooting where they were directed to.) They are air-mobile--but knights can't harm aircraft, they only have transport aircraft and they have no defenses at all. If the missile booster has burned out they will have no idea it's coming until it hits and they are built like civilian craft--no attempt to minimize battle damage. They are not carrying the supplies to turn around and head home with their metaphorical tails between their legs. Their only choices become suicide or surrender. To make it even harder on them they might be using some sort of non-inertial drive--the power to cross the stars is not the power to move large rocks so kinetic bombardment isn't an option. (Note that I do not mean only something like the intertialess drive of the Lensman series. Warp drives partially fall into this category. The drive used in the Starfire series (David Weber/Steve White) also come to mind.) [Answer] Westmoreland: You never beat us in a pitched battle. Giap: I didn't need to. tl;dr Study Vietnam, and also the Eastern Front in WW2. [Answer] Well, you could do something like in War of The Worlds, towards the end of it, all the Martians died out because they got infected with human diseases, like the flu and the common cold. Essentially what happened when the American Settlers came into contact with Native Americans. Their immune systems were not ready to fight of a incredibly infectious and deadly disease. ]
[Question] [ In my world, a form of magic exists which allows a person to be revived after death. Prior to death, a ritual is conducted which tattoos a rune onto a person's soul. This rune is connected to a large crystalline structure kept in storage at a secure location. When a person dies, their soul is transported to that crystal, where it gestates for a period of 1.5 years. During that time, their physical body is regrown over the soul, ending in the exact condition that the person was before they died. When the process is completed, the person regains consciousness and is decanted, being reborn at the same age that the person was at death. This process is performed in the case of accidental death, or murder. The process can be done as many times as necessary, providing an unlimited number of lives, but cannot prevent dying from old age. Companies offer this as part of a life insurance package. A person pays for the ritual to be done, then pays premiums every month to keep their crystal functional. Maintaining this is exorbitantly expensive, which can only be afforded by wealthy individuals and their families. Being able to be revived has become a status symbol among the super rich. It has also led to the creation of royal houses, such as House Kardashian, which are made up of wealthy elites and their families. What I want is for this system to not lead to a situation where the reality of death is cheapened. As the process is expensive, it obviously leaves out the majority of the population. However, a member of House Kardashian, House Buffet, or House Beyonce are likely to get careless if they know they have unlimited backup lives. This can create a situation similar to [Altered Carbon](https://en.wikipedia.org/wiki/Altered_Carbon_(TV_series)), in which people have backup lives and see death as a relative inconvenience. How can I prevent this resurrection system from cheapening death? [Answer] Tattooing the soul shows up on the body. You cannot poke a thousand mind-needles dripping with ether-ink into a soul without it lashing back at the body. This shows up in unexpected ways that you can't really use as a status symbol: weeping sores, arthritis, scars showing up unexpectedly. Bones may become brittle, organs may rumble in protest. Allergies could flare up and senses may grow dull. it is never severe, never crippling but always annoying. [Answer] If the goal is to prevent the "cheapening" of death, then add some consequences to that. You have already done that in a few ways: (a) there's a 1.5 year break before they come back - this is disruptive. A president effectively ends his term; a CEO has to give up his business, and whoever takes over won't be thrilled to give up that power after a year and a half; and so on. (b) This doesn't stop death from old age - there is still death, and still lots of it. (c) Very few in this society can afford the premiums. Here are some more ideas to make death undesirable: * The recovery process is painful: perhaps they feel everything while trapped in the crystal; extreme agony. Or maybe the spell wakes them up in the state they died (for example, car crash wakes them up with broken bones; a drowning victim wakes up with seawater strangling them). Those who go through the process may be thankful for life, but the world has moved on 1.5 years without them, and they sufferer a lot in that time. * The spell can have defects: each time it happens they lose motor function, age faster, or something that removes this from being able to happen an unlimited number of times. * Require destruction of the original body: if the body doesn't decay (died in an ice sheet, killer put them in a freezer, were embalmed too quickly), then the soul can't escape fast enough and the crystal dies, making death permanent. * The soul tattoo can be removed: high-tech assassins charge their clients a premium to not only kill the victim, but remove the tattoo from their soul first, preventing regeneration. * Cultural bias: in a society where hated individuals keep coming back, the government might pass laws against the procedure. Since it is known where they will respawn and when, then their house or property may be raided (or taxed by the government) in that time. This can be a type of dual-edged sword: the envy and respect of the poor for the wealthy class, while misuse of the ability being an object of scorn and hatred - this can turn a famed celebrity into an outcast in a year and a half. * The process requires something horrifying or illegal: such as the death of an innocent child to "start" the regrowth of the new body. This would make it obviously illegal and therefore require secrecy, as well as play into the cultural bias against it. The uber-rich may hide this by announcing a spurious 1.5 year vacation, or pay to have others impersonate them in that time, but it still requires a lot of people working together in secret. Coming back from the dead only to spend the rest of your life in prison is not exactly what they wanted! Obviously the mere fact that death can be unwound will cheapen the idea of death in some way, but making that controversial, illegal, painful, or the like will help to prevent people from wanting it, and will also limit the number of times they can do so effectively before they die of old age (or are imprisoned). [Answer] Everyone else says "you can't" - however, Time is a currency, as is Information. Especially for the Celebrity Houses, such as House Kardashian. Death results in you being completely, and utterly out of the picture for 18 months. No new projects being released, no responding to the latest changes in fashion or pop-culture. Someone else will step up, and fill your slot on the Social Scene - since "Death is Cheap" for the rich, it won't have the same media coverage (unless it's a "final death") or staying power. The world will move on, and quite possibly forget you. Once you re-emerge, you need a crash-course in everything that's changed - otherwise, you're going to look like a has-been, you won't get anyone's references, and you'll accidentally insult someone who is actually important now. Consider that if you Died in May 2015 then when you were decanted (in November/December 2016) you would discover: * Cuba and the USA had resumed Diplomatic Relations * Gravitational Waves have been discovered * Liquid Water has been discovered on Mars * David Bowie died (Old Age, no coming back) * Alan Rickman died (Old Age, no coming back) * Harambe died * Pokémon Go was released * The President of Brazil has been impeached * Donald Trump has been elected President of the United States of America * The Chicago Cubs won the World Series * Brexit has begun [Answer] A life for a life Sure the ritual will bring someone back to life but it requires a life to power the ritual. Nobody needs to be murdered but someone can choose to sacrifice themselves and their family will be heavily compensated for their gift. If you think about it, it's the next logical step after buying a kidney from a poor person (on the road to damnation) There are people rich enough out there to buy a life and people poor and desperate enough to sell their own life. [Answer] You remember the death. Were you tortured? Did you drown? Did a rabid dog bite you to death? How many hours were you in agony? Welcome to a new world of waking up screaming every night. Will the nightmares ever stop? You remember staying dead. Do you remember the emptiness? The nothing after? Religion say otherwise. Doctors say it was your disconnected brain. But you were there, you felt it, and there is nothing. What is the sense of it all? Is there any purpose? Is that what is awaiting for you? *Your soul will forget how to cross the river*** Souls know how to cross by instinct. Dull the instinct by forcing the soul to stay among the living, and the soul will stay forever, with or without body. Ah, but the nightmares stay. Returning is the new life-on-a-wheelchair. It's even worse than just dying, both physically and spiritually. That's why it is so rare nowadays. Even rumors say the ultrarich have their pet slaves and servants on insurance, but not them. Only they know for sure. [Answer] You can't. This is unpreventable. Sure, you can attack penalties to mitigate it. One and a half years is a long time to not be around, you can have monstrous costs involved, you can have pain and necessitate long periods of recovery. But in all actuality? This is a Pandora's Box you've just opened. The acknowledgement that Death is permanent is a huge cornerstone of culture (see [Memento Mori](https://en.wikipedia.org/wiki/Memento_mori)) and will have lasting and devastating consequences (especially among the religious). Especially considering that this 'unattainability' won't last forever. Personal wealth has been on a consistent rise for the past century and shows no sign of stopping - in fact, it may as well scale with technological improvements. Combine that with natural capitalist impulses (you mentioned House Buffet - presumably Warren Buffet would seek to profit off this) and within a few centuries, suddenly this is affordable to everyone. Suddenly, death is a slap on the wrist. Let's say you get mad and kill someone in a drunken brawl. Instead of going to jail for life or getting executed, all you do is pay restitution charges for his resurrection and compensation for his lost time. The murder rate will skyrocket, and now that it's generally affordable, there's a good chance that the poor who can't afford it will be looked down on as second-class citizens. The only upside is that death has been cheapened both ways - sure, you've gone and made it more widespread, but since resurrection is possible, is it really that bad to be killed if it doesn't stick? (I mean, yes it's bad. But it's nowhere near our permanent level of bad.) [Answer] People wouldn't kill unless they wanted it. As respawning cheapens death, you already have set up a decent cost if they die. One and a half years is a long time. But depending on how you want to show it. I reckon if someone knew, that if they killed someone and that they would respawn, then they wouldn't bother killing them\. Instead, I think they would capture the person, torture them, but keep them alive, if barely, and make sure they weren't able to take their own life to flee captive by respawning. \You still may want to kill them if want you wanted to achieve a goal in less than 1.5 years. For example, killing a powerful king then taking over his kingdom right afterward. An idea. It could be used as a method to "fast travel" through time. As you respawned, you go through the ritual again, die and repeat until you're where you want to be in the future. But back on to your question, how to prevent it feeling cheap? You would need to have a heavy cost. Lazy writing way of this would have them lose their memory. It's done often enough, but you could always start the story from someone who's just come back alive and has to learn the world again and this would allow readers to learn with the character. I feel that losing their memory would carry a lot of weight, especially if the story had some kind of love element that would be considered unnatural, such as two kingdoms that hate each other, and each of their respective prince/princesses fall in love. Due to the story plot letting some meet or getting stuck together for a duration and then them acquiring feelings and if one were to die, there would still be a lot of weight because it would a relationship that would be impossible to rebuild, as the situation that let them build it in the first place was a freak occurrence. [Answer] ## Resurrection lawsuits. Death might not be permanent, but resurrection is still expensive. Which basically means that killing someone is now more or less the same thing as severely injuring them and putting them in the hospital for a year and a half. And severe injuries means lawsuits. Wealthy people might be a bit more reckless with their own lives (although still not very much, because losing a year and a half is a pretty big deal, especially when you're not even able to manage your losses), but putting someone else in the hospital is still something you don't want to be known for, even if you have the money to pay for the recovery process, including lost wages and emotional trauma. In some ways it's even worse to injure someone than to kill them through negligence - killing someone accidentally might be tragic, but killing someone when you have the means to revive them means you now have to revive them, and that costs money. Altogether, I don't expect there to be so many changes in society due to this technology. People don't want to spend money if they don't have to, especially if it comes with a major inconvenience. [Answer] In this age of instant gratification, who is willing to wait 18 months for you? Does your spouse really love you enough to wait for you to be reborn, or will they stray? If they are wealthy in their own right or if they are dependent upon your wealth, you won't be there to make sure that gold-diggers don't try to seduce them. If your spouse is a celebrity, they will likely be pursued regardless of the wealth or poverty of the pursuers. Who will look after your kids and your pets while you're gone, and will they want to come back to you when you return? A year and a half is a long time for young kids. If you are female and were pregnant, are you still pregnant? It was only your soul that was bound to this mortal coil... so the question as to when a foetus develops it's own soul will soon be answered... but will you like that answer? What of your parents and relatives? There's little doubt that if they love you, they will wait for you... if they can. By the time you can afford to pay for future resurrection, you're likely to be getting on in years, which means that it is more likely that any parent - or aunt or uncle, or especially, grandparent alive at the time of your death may have died of old age in your absence... especially if they are dependent upon your care. Whatever your source of income, will you still have it when you come back? If self-employed, or if you are the owner and CEO of a corporation, will your business even exist after a year and a half of your neglect of it? During that time, your customers may have gone elsewhere if your business has simply suspended trading, or if business continues, whoever has managed your company for you in your absence may have run it into the ground - or embezzled its funds and assets and vanished, or it may have been taken over by another company. If you're a celebrity, you'll have spent a year and a half out of the public spotlight, while other celebrities vie for the public's attention. Unless you have planned well for the eventuality of your untimely death, you'll likely come back to find that you're last-year's news, and face an uphill battle to rebuild your public image, in the face of other celebrities who don't want to give the spotlight back to you. If you are an employee, will you still have a job? Maternity leave is six months, and it has been a hard fight for women to be able to go back to their former employment afterwards, and you want your employer to hold your job for three times as long? If you're easily replaceable, you wouldn't likely have the money to be resurrected, so that means that you would have a job that requires a significant amount of skill... though in 18 months, your employer would likely have found or trained a replacement - especially if you are easily replaceable, and you'll be 18 months out-of-date. If you live with someone, will they have left you your belongings, or will they have appropriated them? If you lived alone, you'd want to have good security, in case your place gets burgled... and that's only if you owned your place of residence. If you were renting, did you make arrangements to pay the rent in your absence? If not, you could find your belongings in storage (or just gone) and someone else in your former residence. Even if you owned your place of residence, did the bank foreclose on your mortgage? Was it seized because the rates and utility bills weren't paid? Has your car been impounded or stolen if you left it in a public place? If it was garaged, will it still run after a year and a half, or has your partner continued to use it, and crashed it, run it into the ground, run off with it, or perhaps returned it to you in good condition, only with a lot more miles on the clock? If you're wealthy, you may replace your car often... only this time, it could be up to a year and a half older than you usually let your cars get before you replace them, and not be worth as much. There will likely have been at least one, and possibly as many as three newer models released while you were gone. Now do you think that death is cheap if there is resurrection? [Answer] The degradation of body after each revive. With each revive, the "clone" ("the physical body is regrown over the soul, ending in the exact condition that the person was before they died") is an copy of body when that person die, and the body is make on-demand (" When a person dies, there soul is transported to that crystal, where it gestates for a period of 1.5 years. During that time, the physical body is regrown over the soul, ending in the exact condition that the person was before they died"), not pre-made. When that person die again, then the process "the physical body is regrown over the soul, ending in the exact condition that the person was before they died" start again, which is making a clone from a clone. And again, make another clone from the clone that is base on a clone. So, if one person keep dying, they will notices that their body is not as good as the original one. You can do a simple experiment in real life: make a color copy of an picture (black-and-white copy of text is too simple to see the degradation), then make a color copy of the color copy, then keep doing that. With each copy, the quality degrade because you can never get 100% information pass on. Money is not the only price you pay, you paid the price of mutation. Mutation stack on top of another mutation with each revive, the suffer is increase, become weaker, slower ,ugly, look like monster, depend on each mutation. Mutation is noticeable at first few review, but ... There will be a threshold that the mutation is too great to bear. But most people will choose to end their life before they reach this threshold. [Answer] Even with this case, dying is still inherently risky. Others have talked about the consequences you've already included, like the year and a half in purgatory timeout. I'm going to touch on some others that are closely related, and those risks are: capitalism and political power plays. Your world states that companies controls this process, a process which is incredibly powerful. Literally everyone who can take advantage of this ability to "undie" is going to want... certain assurances that this ability continues to be available to them. Particularly powerful individuals who may have some rivals/adversaries might also want to, say, strategically deny this access to others. Since it sounds like the infrastructure costs are really high, there probably isn't a whole lot of companies capable of supporting this venture and the power struggles to control these companies will probably be immense. The buyouts, the bankruptcies, the hostile takeovers, and don't forget the corporate and political espionage and sabotage. The fact that there is still physical infrastructure in addition to the magical infrastructure means there are still points of weakness in the rebirth system. If there were to be an "accident" with someone's crystal, what happens to that person and their rune? What happens if that "accident" occurs while that person is being reborn due to an "accident" that they had a year or so ago? Are the crystalline structures dependent on some kind of resource where they are managed in groups? What if one of those groups goes offline for maintenance, or... "offline" for "maintenance"? This ability also sounds really valuable for governments and particularly for covert and military operations. There's no way governments across the planet wouldn't want direct control over who can access the ability to be revived. Being able to send an agent into deep cover and being able to get that asset out through extraction or death is an extremely powerful tool in a government's covert toolkit. Even better if the agent's cover is left intact when they die. Denying rival governments this ability is going to be equally important. Another aspect is how the general population views this new fangled ability. Domestic terrorists that view this as unnatural and "playing God" could also attempt to disrupt this system. And don't forgot your political lobbyists, who will attempt to exert political pressure in favor of or against the development and management of this magical technology. Just due to political and corporate uncertainly alone, not to mention being out of action for a year and half, is enough incentive to not entirely rely on this process. It is still entirely too risky to treat death as trivial. This death prevention system is, at best a last-case scenario for the wealthy and powerful and a calculated risk for agents who are operating in the service of those wealthy and powerful individuals, and nothing more. [Answer] > > When a person dies, their soul is transported to that crystal, where it gestates for a period of 1.5 years. During that time, their physical body is regrown over the soul, ending in the exact condition that the person was before they died. > > > Change this so that their new body continues to age as it is regrown. That way they wake up not just having missed 1.5 years of events in the rest of the world, but actually missing 1.5 years of their lifespan that they otherwise could have lived. This obviously isn't as bad as death, but it is still a pretty big deal that people would try to avoid. You are unlikely to be willing to undergo this process for minor matters, especially not repeatedly. Do this 10 times and you've lost 15 years - a significant chunk of your adult life. It is certainly nothing like "unlimited backup lives". [Answer] Death is not cheapened, because the treatment is not 100% reliable Let's say that in about 1-2%\* of cases the treatment fails. This outcome is absolutely unforeseeable, (maybe there is a reason why it fails, but the explanation is out of the reach of the current technologic/magical research) so there is no way to be sure about coming to life again. Obviously, in case of fail, insurance companies have to pay a high indemnity to the relatives, but the insured person is absolutely dead anyway. Knowing that there is a small percentage of perma-death, even if you have that kind of life insurance, you would still think twice before putting yourself in a life-threatening situation. This way death would still remain impredictable enough to be feared \or a higher/lower chance, according to how much you think the people in that society are risk-prone [Answer] The tattoo takes two years to become functional. If you die early during this "acclimation period", you're as dead as someone who hasn't gone through the ritual at all: no harm, no foul -beyond, you know, being dead- but your investment has been for nothing. This risk is, of course, factored into the price. If you die late in the acclimation period, however, well, that's arguably rather less fortunate, because then the tattoo actually kinda-sorta works partially, but there are... glitches. And not the pleasant sort. The tattoo also dissipates when used, but the ritual can be performed again, and the process restarted, as soon as your soul is back at the crystal, for a reasonable fee. So when you wake up again, the acclimation period is already mostly finished, and everything's all hunky-dory, right? Well, sort of: you also wake up "late" in the acclimation period, when an early death will* lead to the dreaded glitching. So when you die, you wake up to six months of terror and paranoia while your soul finishes acclimating to the new tattoo. Thus, even coming back right is a highly unpleasant process best avoided. It also means you have to watch out for murder attempts coming in pairs... [Answer] It's not that you can't be killed any more, the way to make sure someone is permanently dead will just be more elaborate: First, destroy the life-saving runes, and then kill the victim. I mean, if you can put runes onto the soul, you also can destroy them. Or maybe there's a way to reconnect someone's runes with a different crystal, one you are in control of. Possibly this can be done even without the victim noticing before death. So there's a real risk that instead of regrowing in that safe facility, you instead regrow right in your enemy's prison cell. Presumably such “soul redirection” is not easy (and certainly highly illegal). But if your enemy gains enough from it, there's nothing that will stop him. On the other hand, if destroying runes or later soul redirection is not possible, then this might be used to “capture” someone's soul, by doing the ritual on them against their will, binding them to a crystal controlled by the capturer, and thus holding those people in hostage for their whole life. Should they ever die of anything but old age, they will return under those people's control, and even though they know it, there's nothing they can do about it. People to whom that happened might be extra careful with their life, as death will not be an escape route; quite the opposite. [Answer] ## Risk It may not be 100% reliable. If there is a 1% (for example) chance that death is permanent even with this ritual, then you might be careless a few times, but at some point, your innate feelings about probability will keep you careful. Few people who make it to 99 deaths will be willing to risk that they are going to beat the odds. Most people would take care a lot sooner. Alternatively, it might increase the risk of some fatal ailment, so the more you resurrect, the more likely it is that you will permanently die at a younger physical age. ## Otherness Without limiting resurrections in some way, your system buys the deceased an extra 1.5 years of lifespan in their current condition. I would imagine that a culture would arise consisting of rich people aged (maybe) 35 and up who all live for 18 months and resurrect for 18 months at a time, thereby reaching the physical age of 60, 85 years after their birth, putting off the inevitable final death. Something about being in or out of this gang might be significant. You could make a virtue of the cheapness of death in this way. If you refuse to die at your allotted time, or you die when it is not your turn, you could be punished in some way. ## Peer Pressure The fact that it takes a long time means that the deceased needs a support network in place to look after their affairs for those 18 months. If that support network is made up of other resurrectionists, then each death puts an extra burden on them, and careless deaths would be frowned upon. You may be ousted and disinherited or have your wealth confiscated if you die too often by your own stupidity. ## Revolution Your support network may be made up of employees without access to infinite lives themselves. If you die too often, they will realise that you are actually a parasitic oligarch and get rid of you - maybe transfer your investments elsewhere so that you are no longer rich when you come out or secretly not pay your insurance premiums so that your next death is permanent. ## Actuaries Insurance companies are not charities. They don't like to pay out more than you pay them, and charge more to cover the likelihood and size of payouts. In real life - * Drivers have higher premiums after an accident * Travel insurance is more expensive when you add "dangerous sports", or if you go to USA etc. * Pre-existing conditions are excluded from health insurance packages * Pilferage is normally excluded from theft claims (i.e. if you didn't take care, you don't get the payout) * Fraudulent claims are contested (e.g. you burn down your own property) Every time you die, your premium could go up significantly, such that even Bezos might think twice before dying for a 5th time. The resurrection process might take 18 months, but if you die doing something that the insurance company thinks you should not have been doing, then your lawyers could be arguing for 18 months before the process even starts, or they might refuse to resurrect you the next time. [Answer] Remove the soul part from it Make your magic working without any effect on the soul. Let it just regrow the body. In that case, similar to popular disassemble-reassemble teleportation mechanics, the revived person is just a perfect copy. In that scenario if a person dies it is permanent from this person's point of view. Yes, a copy will be assembled somewhere else, but it is an absolutely independent living thing even though it is a perfect clone. And it is a clone. There are couple of benefits with this approach: 1. The death is still scary and totally unwanted. Every one is mortal again. 2. You can actually remove all other "handicaps" like 1.5 years delay. 3. Assembling a body is arguably less "magical" so this mechanics can help you balancing between sci-fi and magic, while your current approach relies on magic almost completely. 4. This is the solution to all tricky questions like "what happens if you die from a decease?". You will be simply reconstructed the way you want - via checkpoints, via genetic modifications, etc. I mean, no one will make a checkpoint while knowing they're terminally ill or going to die in a car accident in a second. Cons: 1. This approach is actually too harsh - the only point in paying for resurrection service is your desire to continue your work even after death, e.g. running huge company or fighting for freedom etc. Otherwise it doesn't make sense, you will be dead anyway, it will be your perfect clone's life. But you have already stated that this service is primarily used by rich ones, so I guess they fit quite well here. 2. Such an idea is already described in Pandora's Star by Hamilton... (but there people don't give a damn about dying which is quite weird). [Answer] Lack of Legal Recognition The government doesn't recognize the process as continuing the individual, but being a new individual who happens to share memories with the previous individual. Legally, they are now a newborn. They will have to go back to school, and if the decanting is in a different country, lose their citizenship. Since they weren't born when 'their predecessor' died, they aren't eligible for inheritance. They effectively lose everything, and legally are starting out as an adult-shaped newborn with no parents or resources. The rest of the family MAY take them in... or may just take advantage of the situation to divvy out everything they had. [Answer] If you look at the Vlad Taltos book series by Stephen Brust, they have a resurrection system that is available to those of sufficient power/ funds but it can be circumvented by various methods such as destruction of the brain or use of certain powerful magic weapons. You already have a method of this baked into your lore. > > During that time, their physical body is regrown over the soul, ending in the exact condition that the person was before they died. > > > Wouldn't being restored to the point immediately prior to death just lead to them dying again if it's done right? If I shoot you in the gut your gonna slowly bleed to death or die of shock/sepsis/etc... So when you come back you still have a hole blown in your torso, so you die again. If the murderer kills them with enough destruction prior to death there's no way they would survive upon revival no matter what medical care is available. So resurrection is available but only if the body is in one piece enough that it can survive with medical care after being decanted. Theoretically doctors could work frantically to repair the body before the patient dies again and then in another year and a half the new body would be partially repair so they can do another marathon repair session to repair the remaining damage repeating the process as many times as it takes to restore the body to a functioning state. This could make the process take much longer than a single 1.5 years before the person comes back and resumes their life. [Answer] ## You Still Died While the time lost and potential degradation due to an imperfect process are interesting technical costs to a problem, there is still the point that the person has died from a current legal and medical perspective unless the laws change to take this into account. There is no indication that this is the case. As a dead person your will would be activated, regardless if you are going to be back in a year and a half or not. Your estate will be processed, you fall out of lines of succession, your social media is memorialized and closed down, estate taxes, etc. Then there is the issue of reestablishment of living status once the resurrection is complete, which means even more paperwork as well as money the newly living person may not have anymore if they were careless. Never underestimate the amount of paperwork a government can create for something. Resurrection paperwork … in triplicate … filled out by the newly resurrected person … by hand for each copy … and you have to explain the cause of your own death … and a small mistake may keep you in legal limbo for years. Yeah. What this may also mean is that it is quite plausible that there is a time when the newly resurrected ultra-rich human is actually not legally a person. My memory is a bit fuzzy on the matter, but this kind of thing was in the Girl Genius webcomic, where death removed nobles from lines of succession, even if they were resurrected after. Which in a world of Mad Science is a distinct possibility. Also, there is nothing in this life insurance policy that states they deal with any of the bureaucracy of personhood status before, during or after your death. I can see the paperwork services costing extra. Bureaucracy, the hidden cost of everything ... ]
[Question] [ ## Context On my world, there is a lot of water: sea, oceans, ... There are also firm land and islands, so it's interesting to travel on the water. The problem is that there is NO wind at all, and lots of currents. These currents are mostly tidal: basically, they go in one direction for some time, then in the other for nearly the same amount of time, at more or less the same speed. It is hence impossible to practice normal sailing, the boats would just be moved around by currents and getting nowhere but reefs. The technological level is equivalent to what was available on earth during the 17th century. ## Question The boats must be able to choose where they are going, and not merely be moved around like cork would be. I'm thinking about two possibilities, but I am unsure if these are viable: * Use an anchor when the current is not going where you want to go. (Problem: it's difficult to move sideways from te current). * Reverse the concept of a boat: use small "sails" underwater for propulsion, and enormous sails in the air to steer and prevent drifting. Is there a possibility to use the currents in order to move a boat toward its goal? [Answer] ### Relativity According to relativity, a strong wind with negligible current is locally identical to a negligible wind with a strong current. All of the sailboats that exist today would work just fine in this new environment without any modifications. The issue is they would sail relative to the current. This means if the current is 30 knots, on the sailboat it would feel like you have 30 knot winds and you could sail using the exact same techniques. The difference would just be that in addition to whatever normal sailing speed you were managing, there's a 30 knot offset in the direction of the current. ### With the current This one is pretty easy. When you're trying to sail with the current, you're effectively trying to sail upwind. There are a lot of boats that can sail upwind at about 60% of the wind speed. [![Boat speed vs. angle](https://i.stack.imgur.com/KVQvY.jpg)](https://i.stack.imgur.com/KVQvY.jpg) ([source](http://www.sailingbreezes.com/sailing_breezes_current/articles/Feb06/dell.htm)) In this image we can see how fast you can travel on still water with a given wind speed and direction. Basically, you can travel fastest to the sides, at nearly 100% of the wind speed (high performance boats can exceed 100% to the side), around 55% upwind, and 65% downwind. Then you get to add the current speed back in so you should be able to sail a normal sailboat at about 155% of the speed of the current when you're sailing with the current. ### Against the current If we repeat the math from above now you get that we'll sail at 65% speed downwind (upcurrent) but then when we add the current in now we're going at -35% speed. Uhh Oh.. now we'd be making negative progress. ## Solutions ### Just deal If the currents change direction often enough we could just deal with it. If half the time we're making 155% progress and half the time we're making -35% progress we'd still average 120% progress. So we'd still be able to make it to our destination faster than the average current speed. ### Propellers So we'd like to be able to sail downwind faster than the wind. Sounds impossible, but we've actually already achieved something similar: [A wind power car than can go 2.86 times the speed of the wind](https://www.wired.com/2010/06/downwind-faster-than-the-wind/). In the case of the car, the wind pushing on the propeller gives the car thrust to move forward. The wheels then take a portion of this forward energy and direct it back to the propeller to blow backwards. This additional energy allows the wind to provide additional thrust, which then goes into an amplifying cycle only limited by friction and wind resistance (as the vehicle is going faster than the wind so it net blowing against it) So we can adapt this same technique to a boat, but instead of wheels we'd need a water propeller. The idea would be that the wind would push on the air propeller driving the boat forward. Some of this forward energy would be absorbed by the water propeller which would drive the air propeller into action giving us more thrust to move forward more. I doubt we'd be able to achieve the amazing 2.86 times the wind speed, but we may still be able to achieve something meaningful using oldmill technology. If this technology worked well, it could actually be used to sail upwind faster as well, by reversing the gear ratios to let the wind propeller power the water propeller. ### High Performance Sailing Turns out it rather than using a typical earth sailboat, you use something like an 18 foot racing skiff, you can sail faster than the wind in pretty much any direction: [![Performance Sailing Boat Polar Curves](https://i.stack.imgur.com/EezdG.jpg)](https://i.stack.imgur.com/EezdG.jpg) With a boat like this you'd have no problem sailing upcurrent. I took the liberty of making a modified graph of how these boats would behave relative to solid ground: [![Wind relative Polar Curve Plot](https://i.stack.imgur.com/wCf9o.png)](https://i.stack.imgur.com/wCf9o.png) Of course this probably requires modern materials to achieve. [Answer] You can't control your direction in a sailboat when there is just one current. Sailboats are only able to move into a different direction than the wind is blowing because they have a "second sail" under water, called a [keel](https://en.wikipedia.org/wiki/Keel). The actual physics on a sailboat are a complex topic. But the bottom line is: When the aerodynamic force on the sail and the hydrodynamic force on the keel act in different directions, then the sailboat can move into a direction which is neither. However, when the wind speed over land is 0 but you are drifting in a very fast current, then you actually feel an airstream just from your movement. That airstream can be used to maneuver by sail. You won't get a lot of speed and you certainly won't be able to sail up-current, but it might be enough to jump from one current into a different one which goes in a different direction. It would be like sailing, but in reverse. Normal sailing is exploiting air currents in stationary water. In your universe, it would be exploiting water currents in stationary air. [Answer] ### Rowing If you don't have motors, it's back to good ol' muscles, like Egyptians and Romans used to do. The only alternative is that if somehow there is another, intelligent enough marine species that could be trained, you could use those animals to pull the ship along the seas. EDIT: TECHNOLOGY LEVEL On Earth, the first functioning steam-propelled ships appeared in the 18th century, but they were prototypes prone to break down within a short time (often less than one hour). Only in 19th century there would appear the first true steamboats. And they were affairs made more to cross rivers than oceans. Of course, given the pressure of obtaining a steamboat as fast as possible with no other options available, it's reasonable that the Watt engine is conceived even two centuries before than on Earth. NOTE: Chimneys cannot be vertical tubes, or when you turn them on, first thing you cover the ship with soot. Ew. I think they should should be shaped like a car's exhaust tube, horizontal with the holes in the stern and additional filters to collect the soot and emptying it in the sea. (yes, very little ecological, but any civilization at its first invention will do ecological damage before improving their transportations) --- ### Further considerations for this world No winds at all implies that any kind of gas pocket will disperse by its own pressure along the surface, or rise in accordance to its weight, but limited by the pressure it finds. In other words, a volcanic gas column will keep falling vertically on itself (after the main phase of the eruption has subsided) and keep spreading all around the volcano, permanently poisoning a growing area until much more land is lost for a very, very long time. Any fume caused by the people activities (sewers, chemicals, even the animal wastes in the streets and in the farm) will stay where it is, progressively polluting the area to the point of suffocation. All hot air will stay where it is, in pillars that would make flying for birds a near impossibility. In order to fly, an animal should be like a gigantic manta with low dense tissues and humongous floppy membranes to catch all the thermals they can in one sweep. Plants that need impollinators would need land mammals to coat with their pollen. These mammals could look like tiny kangaroos so that they can hop faster in a field and spread the good stuff. On a good note, viruses and bacteria that need currents to move would stay where they are along with their victims. Once their preys are consumed, they will revert to a sporal state so to be carried by passing animals or unsuspecting people. Tall plants would also be very different: to transmit DNA and warn each other of biological attacks, they'd be connected to each other in a thick web of creepers, that would also serve to reinforce each other with nourishment. And people could use the creepers as roadways in this new upper-level ecosystem. Swamps would be pots of pure undiluted poisonous CO2 and other nasty gases. Deserts in daytime would be even more suffocating without any breeze to disperse the heat. presumably, they'd even be hotter. Lakes would, well...stink! Not that their water wouldn't be drinkable, but you wouldn't want to stay in a place that stink of dead fishes and dead algae Of course, you don't want to venture in a canyon without a gas mask, unless you like your deposits of CO2 Also, humanoids would much look like Voldemort! In a currentless words, no species needs sense of wind-carried smells anymore. They could breathe through gills that would also serve as air purifiers. Every species' tastebuds would be extremely more refined to distinguish toxic from edible. Possibly, the standard tongue would look more like a snake's. Predators should rely on augmented vision to better hunt. Instead of scent tracks, they's release a substance that leaves a visible mark at night. I can think of only one reason why this world is not reduced in a hellish nightmare coated from pole to pole by a layer of heavy toxic gases, and that reason is: Bacteria. A form of microlife evolved to eat up all the nasty stuff and spew oxygen 24/7. On land, they'd appear as plants, on water as a thick plancton presence culled by fish so that it doesn't turn the oceans in a soup. [Answer] Sailing in any direction other than straight downwind is an exercise in balancing wind resistance against water resistance. Since the wind doesn't apply as great a force on your vessel you need larger sails relative to the size of the submerged hull. To move solely with the current, you do not have to make any changes to the design of your hull, however you will not be moving in a controlled manner, to have control of a vessel you must have movement relative to the water or otherwise exert a force on your vessel relative to the water. Currents are not simple laminar flows. There are weaker and stronger areas of flow, there are eddies where the flow effectively runs backwards. In a steadily flowing straight river, the flow will be strongest in the centre and weaker towards the edges. On a bend in a river the flow will be strongest on the outside of the bend and weaker, even to the point of forming an eddy on the inside. Wide shallow rivers have slower flow than narrow rivers. Obstructions in the river will cause faster flow around (and over) the obstruction and an eddy with backward flow behind it. What this all means in the long run is that with only minimal paddling or rowing you can have considerable control of a vessel without having to constantly power your movement. Consider the competitive [canoe slalom](https://www.youtube.com/watch?v=sETxQfEbo08) event. Visually you see powerful paddlers with a large blade in their hands fighting the current to pass through gates in a given order as fast as they can. They're not fighting the current though, they're riding the current, dodging in and out, finding stronger and weaker flows and eddies as they need. The "upstream" gates are not against the flow, but in eddies where the flow is running backwards, then out into the strongest flow to get back up to speed. Winning is not in fighting the water but in best reading the flow and using the water to your advantage. The same is true of ocean currents, they're not simple things, they shift and swirl around islands and continents. There's a correct and a wrong way to sail round the world as a result of all this. Getting the currents right makes a massive difference to the speed of a crossing. All your boatmen will be expert readers of current, where to be and where not to be and how to place their boats to travel their routes. [Answer] I'm afraid your suggestion of huge sails won't work for a couple of reasons: 1. Engineering. 17th century ships had wooden masts, and you simply wouldn't be able to make a wooden mast large enough for your purposes 2. Physics is also against you here. For this to work, the force exerted by the air has to be similar to that exerted by the water (you don't need to stop your movement downwind - so to speak - just reduce it enough that you can make headway towards your destination). The issue is our old friend $F=MA$ - water is around 800 times denser than air, so (assuming roughly equal speeds through water and air) you'd need several hundred times greater sail area than the area exposed under the water. Unfortunately for you, boats displace a fair amount of water and so tend to have a large underwater area. Check out this image of a galleon: [![enter image description here](https://i.stack.imgur.com/MBxrv.jpg)](https://i.stack.imgur.com/MBxrv.jpg) While the design would of course change, the hull volume is probably going to remain fairly constant. So, what can we do instead? ## Anchoring This is a good idea, and one that sailors already make use of. It's normal to try and travel 'with the tide' so as to increase your speed over the ground. Where this might fall down is the depth of your oceans. There are practical limits to the limit of anchor chain you can carry, and if your ship finds itself somewhere deeper than it can anchor it might be in trouble. ## Rowing This is a nice, low tech solution and on your world it might work even better than on Earth: one of the big drawbacks of galleys is that they need to be long and light to work well, which means that they can't handle rough seas. Fortunately for you, the absence of winds means that your seas should be exceptionally calm. Humans do get tired rowing for long distances, but [people have rowed across the Atlantic](https://www.independent.co.uk/news/uk/british-amateurs-smash-atlantic-rowing-world-record-four-oarsmen-atlanic-ocean-charity-race-mind-a8157261.html), so it's definitely feasible. ## Treadmills, Propellors and Paddle wheels Paddle wheel powered ships (think paddle steamers and pedalos), like the galleys, struggle with rough seas - this is why you tend to see paddle steamers only on rivers or lakes in the real world. Here, we have no such problem. The treadmill has been around since Roman times - we can simply connect a couple of them up to paddle wheels on the side of our ship and get people (or animals) to walk in them (this [has actually been done](https://en.wikipedia.org/wiki/Paddle_steamer#History)). This has the benefit of being a reasonably simple mechanism, and allows people to power the ship with their legs instead of their arms. Humans are incredible endurance walkers, so this should be much easier on your crew than rowing. Somewhat more complex would be to use a treadmill to power a propeller - these are more efficient, but would need more engineering to make work. ## Development of steam The development of steam engines covers about the same period as you're looking for - [Jerónimo de Ayanz y Beaumont](https://books.google.co.uk/books?id=rqXpwBO1AX8C&pg=PA207&lpg=PA207&dq=jer%C3%B3nimo+de+ayanz+y+beaumont+steam+engine&source=bl&ots=QA8_DxqLf-&sig=Cpy_OsOQ_oeDDDDuut8GFlpjCD8&hl=en&sa=X&ei=UZWxU67kNIyOyAS28YGYCQ&sqi=2&redir_esc=y#v=onepage&q=jer%C3%B3nimo%20de%20ayanz%20y%20beaumont%20steam%20engine&f=false) had a steam engine working in a silver mine in 1611 and [Newcomen's Atmospheric Engine](https://en.wikipedia.org/wiki/Newcomen_atmospheric_engine) dates from 1712. Given this, and the massively increased benefits of developing steam locomotion for ships, it's not unreasonable to think that these steam engines would have been used in ships much earlier than they were in history - the first steam-powered ship was built in 1704 by [Denis Papin](https://en.wikipedia.org/wiki/Denis_Papin). The widespread use of mechanical (albeit human-driven) drives would also speed this development. [Answer] As an amateur sailor: ## Sailing using the Tide As Philipp stated, sailing exploits the kinetic energy of air with respect to the water. If the air is fixed with respect to the land while the sea moves with respect to it, there will be relative wind when drifting with the current. If the moving air has non-zero density then it will have momentum and thus exploitable energy. As an example, the practical sailing technique of 'lee bowing' uses the effect of tidally-induced relative wind to increase ground speed to windward when sailing across a tideway. For an explanation see, <http://www.pbo.co.uk/seamanship/nav-nutshell-lee-bowing-defined-41887>. # Anchoring in a tideway ## Don't go backwards! As you surmised, anchoring (even in relatively deep water) is practical and useful when becalmed in an adverse tideway. It is much better to stop than to drift backwards. ## 'Sheering' When anchored in a tideway it is possible to 'sheer' off to one side by using the rudder to angle the keel to the current. This is a bit like flying a kite, but sideweays. You could then drop another anchor, raise the first and repeat the process. In practise it may be easiest to have a tender help raise the anchor from which you are sheering, using a 'tripping' line. Sheering (once) is useful when rafting up to another anchored vessel. ## Controlled, continuous sheering? Now for the clever bit: if we could controllably drag the anchor from which we are sheering then we would not need the step-and-repeat process. What we want is a sort of underwater tether that resists sideways motion (with the current) but allows motion across the current. In its simplest form a mushroom anchor with its shank bent and its disc free to rotate might do the trick when you have a smooth, sandy bottom. Given that this should work, I would be surprised if this has not been tried, somewhere. # Conclusion Relative motion implies exploitable energy. Air versus water is sailing. Water versus land is practical but rarely employed. I have used lee bowing, anchoring to stem the tide, and sheering (through a relatively small angle) while sailing small vessels in the English Channel / la Manche. [Answer] Yes, you could turn a sailboat 'upside down' and generate lift from the currents. Sailing doesn't work because the wind pushes on the sails. It works by creating pressure differentials which suck the boat forwards. You control the direction of the boat with the 4 foils (or more) - the main, jib, keel and rudder. Most boats only have one adjustable foil below the water: the rudder, but it is entirely possible to design a boat where the keel also rotates. In your boat, the pressure differential of the sails would come from apparent wind, the force you feel on your face when you drive with the window down. This force would balance against the pressure differential created by the keel and rudder, moving your boat forward. It's hard to know how fast you could go - in most places in the ocean, it is rare to see a current that passes 2kts, but there are places where the currents go up to 17kts. [Answer] As mentionned in some answers, the key lays in the difference in speed between the water and the air. But in your world you can't, so you need to exploit the difference in speed between water and water. For this you need multiple contacts with the water, and there is two solutions for this : * One boat with multiple keels, something like a trimaran but probably with more keels and extremely large. Some keels will stay in the center of the current where the flow is the strongest, some will be stay far from the center, or even outside the current. This way, by changing the underwater area of some keels, for example by using fins, you can change the balance of forces and make the boat rotate. * The other solution will also exploit the difference of speeds between inside and outside the current, not by using one boat, but by using a fleet of small boats connected together. In both case, the keels or boats at the center of the current will act as the engine, dragging the whole boat or fleet, and the keels or boat in slower water will act as the rudder, by increasing and lowering the underwater area or by changing their directions, thus pulling the boat or fleet at one side or the other of the current. I hope it is clear enough to give you a lead. By the way, hello Stack, this is my first message here :) Edit : An other idea for using huge sails : if your currents are really fast, instead of building sails supported by a heavy mast, you can transform them into kites so that they support themselves in the air once the boat is fast enough. Thus you can have larger area for the same weight, but you need to go fast enough to keep them in the air. You can also use hot-air balloons that can also support themselves, but it implies the need to generate hot air. [Answer] It is a question of technology. A modern Americas cup sailboat can easily move against the current with no wind. Here's the link to to designers discussing it: <https://www.youtube.com/watch?v=WBG1g8s3BT0#t=8m40> The example he sites is on the Amazon river with a 12 knot current. Specifically he states the boat could move against the current at twice that speed. However your requirement that the level of tech on your world is 17th century probably rules out such designs, due to the lack of material (carbon fiber) needed to construct the foils, so that the boat can lift itself clear of the water. --- That said, it may be possible to construct a boat with 17th century tech that can sail faster than the true wind speed due to apparent wind: <http://www.boatsafe.com/kids/bramp1099.htm> However in your scenario this would still be relative to the motion of the water, so probably the best you could do would be to move quicker (1.5x) than the current at an actual ground track of about 45 degrees from the direction of flow \\. If the currents are predictable, this amount of control may be sufficient to plan/navigate between islands. \\- I am using a boat angle of about 75 degrees to the flow and a speed through the water of about 130% of the current flow, which is consistent with the second link. ]
[Question] [ In an alternative universe with alternative physics; light, by default, is everywhere at all times. Rays of 'dark' from a dark sun, are initially the only way to dispel the light. This provides day and night on a planet orbiting the dark sun. When the 'sun' is in the sky, it radiates dark and produces night. When the 'sun' sets, day reappears and it is possible to see. Eventually some inhabitants of this universe learn to use technology to make sources of dark. This means that they can sleep even if the sun is not visible, by creating dark in their bedroom for example. Question How can I explain a physics that lets you see by default when there is no radiation, but where darkness is caused by rays of dark emanating from a star? [![enter image description here](https://i.stack.imgur.com/tYcOA.png)](https://i.stack.imgur.com/tYcOA.png) [Answer] In your universe eyes work by emitting a spectral band of sub-atomic particles that interact with and or bounce off objects and return to the eye where they are detected. The 'sun' emits an intense flux of anti-particles so when it is in the sky, the particles and anti-particles annihalate, nothing gets back to the eye and you can't see anything. Artificial 'lights' are just artificial sources of those same anti-particles. [Answer] This may be cheating. It's not that the sun produces darkness, but rather the people evolved for low-light environments and protect their delicate eyes from overexposure to radiation with a transparent film speckled with rapidly-expanding melanocytes. When any point on their field of vision is exposed to bright light, that point's corresponding melanocyte expands, darkening it. We have something similar, but less efficient - our pupils constrict in response to light, darkening our entire field of vision at once to protect our retinas. This is why it is harder to see in a bright glare, even if we are not looking directly at the light itself. This species has it better - they perceive the light itself as "rays of darkness", but they can see everything else just fine. [Answer] Luminiferous Aether! <https://en.wikipedia.org/wiki/Luminiferous_aether> Of course this conception would be different than the 19th century version. In your world the Aether occupies non-solid spaces and to a lesser degree liquid spaces. Aether emits visible spectrum radiation. The rays emitted from the sun alter the emanations from the Aether such that its emissions are no longer visible light. Perhaps they push them more energetically into the ultraviolet, or less energetically into the infrared. I lke the latter because nights would be warm and dark. Either way, Aether emanations are no longer visible to beings like ourselves. Persons with an artificial radiant source similar to that emitted by the star can also locally push aether emissions to the invisible. [Answer] ## You don't Light, and its nature, are deeply and inextricably linked to the physical laws that make our reality what it is. The four fundamental forces simply don't work the same way if the default is light everywhere. Also, light carries energy (which is why using a lens to focus it can light things on fire). Everything constantly being illuminated all the time means a tremendous output of free energy. But that's the least of your problems, because radiation not working the same implies chemistry and nuclear physics doesn't work the same either. There is probably no such thing as 'planets' or 'stars' or 'people' or even 'atoms' in your universe. That's not to say you can't tell a story in a world where this is true. But it does mean you can't really make it be hard sci-fi. Your best bet is to gloss over it with as little explanation as possible. [Answer] Interesting premise. I don't see anyway to explain a visible light spectrum without radiation. Perhaps you can have both though. If in your alternate universe you have photons emitting from some other source, like a Higgs field for light, so that it is emanating everywhere constantly, you could have "dark" created by additional radiation that is perfectly out of phase creating phase cancellation. I'll use audio as an example (I'm a hobbyist audio engineer). If you have two sine waves at the same frequency and amplitude, you'll hear them at whatever frequency they happen to be. But line up perfectly out of phase, you literally cannot hear either. This could also lead to some other odd effects, for instance you could produce an out of phase light at, say 600nm and cancel out your ability to see green. [Answer] In our universe, every object constantly emits electromagnetic radiation (eg light) according to its temperature. This is called [black-body radiation](https://en.wikipedia.org/wiki/Black-body_radiation). When an object is very hot, for example it is lava or has just come out of a furnace, it glows. That is black-body radiation at work. Your body is warm and therefore emits EM radiation at a frequency below that at which humans can see, but infra-red equipment can see it, and that's how night-vision goggles can work. Low-temperature objects emit low-frequency red light, ("red-hot") and as they get hotter they also emit the higher frequencies until finally they emit all visible frequencies, and therefore glow white-hot. So anyway, in your universe either the constants of physics are different such that everything glows in visible light, or the people can see different frequencies such that everything glows in visible light, unless the object is very cold. The stars are a source of cold, therefore putting out the lights. The people who have developed dark-making technologies have actually just developed cold-making technologies. Instead of emitting energy like in our universe, the stars in your universe emit anti-energy that cancels out energy, thereby making things cold. But then if the stars are constantly sucking out all the energy, how is there any left? In our universe things cool because they dissipate energy. Energy can never increase due to conservation of energy. In your universe, energy can never decrease due to anti-conservation of energy. Anti-energy causes energy to build, therefore thank goodness for the stars that cool things once per planet's turn. [Answer] In a universe with "alternative physics" you are seeking to explain the science which underpin this behaviour. But as this science is fictional, it will defy any rational explanation unless you were to set the action within OUR universe, but with some special conditions which might make it illusory - such as how the planet's inhabitants' eyes have evolved. The song title "Blinded by the Light" comes to mind. A real example of this is how ancient civilizations once believed that the Earth was at the centre of the universe and that the sun would orbit the earth. This model worked as far as their limited ancient observations could tell, but of course this was later revealed by science to be false. Those who made the earliest claims that the model was wrong, such as Copernicus and Gallileo were declared heretics and this, of itself, could make the basis of a good story. 'Science Fiction' is mainly about the narrative, not the physics, so you primarily need to consider how this "alternative physics" directs your narrative, rather than how your narrative is going to explain the alternative physics. By way of example, I would refer you to the plot for the Movie "Upside Down" where two estranged lovers live on two conjoined worlds with opposing gravitational fields. <https://www.imdb.com/title/tt1374992/plotsummary> The physics is clearly impossible in our universe, but the author concentrates on the seemingly impossible odds that face these two lovers which are consequent upon this gravitational anomaly, rather than trying to explain how the physics works. The opposing gravity is used as an allegory for the political and cultural differences between the two worlds, of which one is a world of wealth and the other is a world of poverty. Their love is an extension of the "forbidden love" story which breaks the laws of man... and the laws of science. This Sci-Fi storyline echoes other great love stories of forbidden love, such as Romeo and Juliet / West Side Story, Cleopatra and Mark Anthony or Wuthering Heights, and simply accepts that the physics exists, without too much explanation. This odd universe affords some opportunities for comic relief where the main protagonist attempts to overcome the physics by using anti-gravity "weights" tied to his person and in his pockets to stop him 'floating away', in order to reunite with his love. Again, not too much explanation is required, and the audience readily accepts that this is simply how the universe works for the plot to progress. I include these examples to help you think about your universe where the traditional forces of energy appear to be switched. Where a rational explanation appears to be beyond our understanding, you must decide whether it is simply illusory, or if it is real, how does the physics drive your narrative? What are the particular difficulties that the planet's inhabitants will face because of this? Does the arrow of time always flow forwards? Does gravity work in the same direction as ours? How will the protagonists live in this environment? Do they heretically oppose it, or do they discover something more fundamental at work? Is there a conspiracy to hide the "truth"? You don't need to answer them here, but these questions are all about character and story development rather than the "alternative physics". You might also check out the plot for "Dark City", a world with no sun. <https://en.wikipedia.org/wiki/Dark_City_(1998_film)> [Answer] This cannot be done using conventional physics. If you are willing to bend the laws of physics until they snap, there are some options. # A black hole sun is easy The real universe is filled with "light", but it is so dark and redshifted that only special instruments can see it: the cosmic background radiation. Perhaps our universe is younger than our real universe, so it is smaller and the radiation shines brighter, and creatures evolved to see by the light of the background radiation. Moreover, the background radiation in our fantasy universe does not consist of photons, but another elemental particle that could only be formed in the extreme conditions of the big bang. Stars are perfectly normal, and emit perfectly normal photons, but our creatures cannot see photons. They evolved to see only the special particle in the background radiation, perhaps because they emerged on the back side of a tidally locked planet or before their sun ignited. To them, the sun is black, casting a shadow but generating heat. It would look like a "black hole sun", but would not be an effective source of night. # Antiphotons (sort of) If we want more effective darkness, we need two further changes to the laws of physics: the exotic particle that makes up the background radiation is actually an antiphoton, and regular photons only interact with antimatter while antiphotons only interact with regular matter. This has no parallels in real life, but real life has stranger phenomena, such as particles that could be interpreted to look different when you rotate them 360 degrees. "It's quantum physics" could be a valid handwave here. (Note that real world antiparticles are regular particles with an opposite electric charge and opposite quarks, and photons have neither, so antiphotons either don't exist or are technically just photons. Perhaps our fantasy "photons" are baryonic particles instead?) Changing the background radiation to antiphotons allows the sunlight, consisting of invisible photons, to annihilate the cosmic background radiation, consisting of visible antiphotons, creating darkness and emitting neutrinos or other non-interacting particles. Any excess photons from the sun will pass through the planet without interacting with it, explaining why the sun does not generate heat and why the species did not evolve to see sunlight. The sun will not cast "rays" of darkness, but will extinguish the light across the entire sky. On the opposite side of the sun, there is a large glowing circle that does not fully cover its half of the skydome and is brightest in its center, fading to darkness along the edges. The brightest time of the day would be when the sun is directly underneath and the glow is directly overhead, but at that time the horizon would be dark. And every once in a great while, the sun could reflect off a more distant planet and create an "eclipse". The brightness of the sun matters. The sun is always going to be brighter than the background radiation and thus fill space with more particles (otherwise it would overheat and blow up) but particles are small and the incoming antiphotons may survive the flak barrage of photons from the sun and make it to the observer. There is a balance where few antiphotons from the direction of the sun survive but most antiphotons from the opposite direction survive, but it would only generate pleasing results on a narrow band of planets, with most others being eternally bright or fully dark. As a side effect, because the photons emitted during fusion now no longer interact with solar matter, the sun will be slightly smaller, slightly hotter, have a slightly shorter lifespan, lack a measurable solar wind and be slightly more likely to implode into a black hole at the end of its lifespan. [Answer] Similar to echolocation/radar, your inhabitants emit light and perceive it as it bounces back from objects. Just like echolocation (or even picking out auditory speech) requires relatively quiet to be effective, people cannot properly see with so much visual noise. In fact, when the Sun is up their brains perceive nothing with so much background "noise". [Answer] > > How can I explain a physics that lets you see by default when > there is no radiation, but where darkness is caused by rays of > dark emanating from a star? > > > You need to think about more than physics. The terms "light" and "dark" confuse this issue a bit. Those terms were invented long before we understood how light actually worked. They're treated as opposites, but they're two completely different types of thing (one's a physical entity and the other is a description of how much sensory input the speaker is receiving). Replace those with the more-accurate terms "I can see" and "I can't see" and more solutions become apparent. The concepts of light and dark have more to do with biology than with physics. A universe naturally filled with light is easy enough to handwave away. However, your "dark" sun also radiates light. It's not the same light, though. The sun's light and the universe's background light are completely different wavelengths. Your sun is called a "dark sun" because your species' eyes cannot see the particular color of light that your star emits (similar to how our eyes can't see into the infrared or ultraviolet). You know the sun is there because it obscures a section of the sky, but it looks like a big blank spot. Your eyes can't consciously see your sun's light but they're extremely sensitive to it. Your brain interprets this wavelength of light as a "glow". Your eyes are more sensitive to the glow than they are to the normal background light, so the glow overwhelms your senses and will drown out the useful light. You don't perceive the glow directly, but by overwhelming the receptors in your eyes it attenuates the apparent brightness of visible light, similar to how stars disappear during the day. When the sun's light is bright enough, the glow will completely saturate your vision and you won't be able to detect any of the useful background light. You're completely unable to see anything at this point, and you call this state "darkness". This state of "darkness" isn't a complete absence of light, it's merely the inability to perceive any light in the range our eyes happened to be tuned for. Some might say that's being a bit of a language lawyer, but it's literally the definition of what we humans define as "dark". Even in the dark, there's still light present. What we perceive as "dark" may not be dark at all to something like a mantis shrimp whose eyes are built differently. > > Eventually some inhabitants of this universe learn to use technology > to make sources of dark. This means that they can sleep even if the > sun is not visible, by creating dark in their bedroom for example. > > > Man-made sources of "darkness" are easy. Build a light source that generates the same wavelength of light as your sun. Your example use case seems wildly impractical, though. A simple eye mask would do the same thing. [Answer] You could make it work if you willing to add a fictional extra property to particles in physics. When matter and antimatter collide they annihilate each other and release pure energy (as photons). This happens because matter and anti-matter have opposite charge. Light is made of photons however and photons have a charge of zero. Because photons have a charge of zero (and negative zero is still zero) photons cannot be annihilated in the same way that matter and antimatter do. Seeing as existence should have a net energy sum of zero anyway, and there are several mathematical physics equations which suggest the existence of negative energy, and matter/anti-matter annihilation doesn't decrease energy (just splits it into photons), you could claim there is an additional property of particles (lets call it phase) which dictates whether a particle has positive or negative energy. Your dark stars emit photons with negative energy for some reason (so negative phase photons) and every time a negative phase photon hits a normal positive phase photon they erase each other - completely eliminating the energy of both photons. This means that your dark stars will erase normal light. With the logic above, make all matter on your world radioactive enough to emit light. When the sun is up the amount of negative phase photons it emits overwhelms the amount of light released by your radioactive matter, when the sun is down there are too few negative phase photons to suppress the illumination of your radioactive matter. Similarly, if you underground and thus in an area shielded from the negative phase photons, the area will be lit up even during the day. [Answer] Measure of Darkness Negative cancels positive (e.g. electric charges, amplitudes of waves etc.). In our universe, light has positive lumens and darkness means 0 lumen. In your universe, maybe there is a light with negative lumens. Your sun or other devices emit a light with negative lumens which cancels the light of positive lumens. The idea is that if darkness is emitted, there should be some measure of darkness as well. Also there should be sensors to detect and measure darkness. [Answer] How is this In your universe for practical purposes don’t exist individal atoms, the smallest building block is an atom pair. Where the first atoms is analogous to ours (hydrogen, oxygen….) and every single atom is paired via strong atomic force with another, slightly unstable atom, long halflife, but during fission, emmits gama radiation. Now eyes of all the beings in your universe have evolved to be sensitive to this radiation and are thus percieving all the world to be bright. The fusion of the sun however is affected by this secondary atom. Instead of generating light and heat during fusion, the other element absorbs this extra energy and emmits a pair of virtual anti gama photons, most immediately recombine or transition to other particle due to large gravity, some however are expelled and fly towards your world, where they interfere with the naturaly generated gama photons making it “dark” as the human eyes don’t see this virtual anti photon. [Answer] How about instead of seeing using light, the inhabitants “see” the gravity of objects with extremely sensitive “eyes”? Almost everything has mass, so almost everything is visible in gravity. Far away things, and small things, are felt/seen less strongly. If the mechanism of gravity-sight is through detecting tiny changes in the force pulling you in a direction, there could be some fun consequences like acceleration distorting your vision. Objects could be made invisible/dark by placing equally sized objects exactly on the other side of you. A “dark star” wouldn’t need to emit anything - it could be sized, shaped, and located in such a way that it cancels out the gravity of nearby objects in a way that renders gravity-sight too distorted or noisy to see anything. Granted, we’d have to be talking some very specifically shaped and located objects. A potential fun consequence: you could sneak up in front of someone, providing an accomplice of equal mass, shape, and motion was sneaking up behind them at the same time. But the natural world is sufficiently asymmetrical that the gravitational pull of multiple objects around you would hardly ever cancel out, and if it did you could just move slightly to recreate enough asymmetry to see them again. The technology to create darkness would therefore be the technology to precisely mirror objects around a target. Want to sleep in perfect darkness? Go inside a sphere with a perfect inverse-square-scaled model of the universe embossed on its inner surface. I think the necessary sensitivity of gravity-sight would require magical handwaving. [Answer] Let us consider light. In this (the OP's) universe, let light be a massless particle with energy but no charge... much like in our own universe. However, let us also consider anti-light. In this universe, anti-light is also a massless particle with energy but no charge. However, it is also the antiparticle of light. When a particle of light and a particle of anti-light meet, they cancel one-another: When a particle of light meets a particle of anti-light, their energies are summed. If they had equal energy, then there would be zero result. If one particle had more energy, then the energy of the other would reduce the energy of the greater to the sum of the two. As an example, say that we have two particles, a light particle with +5 energy and an anti-light particle with -6 energy. When they collide, an anti-light particle with -1 energy will continue on in the same direction as the original -6 anti-light particle. Let us also consider optical temperature. In this universe, let optical temperature be a measurable property which is expressed as a signed real number, ranging from some negative value, through zero to some positive value. As optical temperature decreases, the particles vibrate less in one dimension and below zero, begin to vibrate more in a dimension at right-angles to the first. However, as objects lose thermal energy and physical temperature, their optical temperature tends toward the positive, not toward zero. Now, let us consider the optical temperature of the universe and the objects within it. Let the universe's background optical temperature approach some value +n. In places which are warmer, the optical temperature will be lower, not higher. If we carry this trend onwards, at some point, hotter objects will attain zero, then negative optical temperature, until they reach the value -n. Now, let us consider the phenomenon of black-body radiation. Objects with a non-zero optical temperature emit radiation. Positive optical temperature objects emit positive light. Negative optical temperature objects emit negative anti-light. The further from zero the value, the more energetic the emissions, positive or negative. Now we need to consider the structure of the universe. The universe is mostly empty space. Cold inert matter which is far from stars will have an optical temperature which approaches +n. Such matter will emit light. Planets which are closer to stars will be warmer, having a positive optical temperature considerably less than +n. They will not emit as much light, and like black-body radiation in our own universe will appear to be a different colour. Stars, on the other hand, are much more energetic, and have negative optical temperatures approaching -n. They will emit anti-light, which will cancel out the positive light emitted from the less energetic parts of the universe with positive optical temperature. So, why have I said that cold and light are positive, while hot and anti-light are negative? Because of what sentient creatures see and describe. The sentient creatures on a particular world in this universe can only see light, not anti-light. That means that they will see the light from all the cold things reflecting off the warmer things, but they won't see the anti-light from the hot things at all. In fact, being close to something hot enough will mean that the anti-light that the hot thing emits will cancel out the light from all the cold things nearby... and will therefore cause darkness. An interesting side-effect of this light/anti-light duality is that there may exist species which can only see anti-light, and they would consider stars to be bright, and the rest of the universe to be dark. Additionally, there may exist species which can see and distinguish between both light and anti-light. Everything would likely be visible to such a species, but light and anti-light would be different colours in a way that those that can see only light or only anti-light wouldn't recognise. [Answer] The planet is not orbiting one star but a binary pair - one light star, the other the dark star. Day time is when the planet is predominantly influenced by the light star & likewise for night, the planet is influenced by the dark star. The dark star produces photons that are out of phase with the photons produced by the light start. When the out of phase photons interact with the light photons they cancel each other out & darkness ensues. Additionally, the light receptor cells in peoples eyes only detect normal phased photons, not out of phase photons. [Answer] I believe that this universe will be the same as the universe where the light works as normal. Just label dark as light and vice versa. Imagine that there is an antiphoton that makes things dark. Then: 1. Light is now the absence of antiphoton energy, which means: 2. Things interact with darkness now. This includes plants and your eyes. Since your eyes interact with darkness, then 3. You will perceive dark things as more prominent. Your color perception will be based on how dark is the darkness on a certain wavelength, if we invert the color scheme, then: 4. Darkness will be basically light in our sense. This also means that people will sleep at day and awake at night. ]
[Question] [ Is it possible to have an aircraft carrier that travels on land instead of water? Assuming that the land aircraft carrier is the same size as a regular one the shape can be different but the overall size the same. [Answer] DISCLAIMER: I'm not an engineer so take everything I say on a conceptual base, because I can't back this up by facts to prove that it would work. Water carriers are wide and flat only because it's convenient for them to be that way given the nature of water. Attempting to adopt the same principles to land vehicles would probably be akin to an attempt to drive nails with a screwdriver (or vice-versa). You have the objective - to drive the object into the wall (house and launch/land aircraft). You have the condition - the nail (land). You are looking at the screwdriver (the seagoing aircraft carrier) like it's almost a solution to your problem which just needs some adjustments. Stop and think about it, sometimes you need to invent a hammer to do what a screwdriver shouldn't. Due to the nature of land not being flat, making something that is stiff will not work when bending pressure will happen, so we have to make something that is able to bend. Good news, there's a good example already available to us. In the real world this is solved nicely in the concept of trains. Think of trains as people-carriers, they house people, they launch people and they land people. Fortunately, as people, we can operate on land ourselves so the launching and landing is not that big of a problem for us, we can just exit and enter the train from the side of it. Although I'm going with the train model in this approach, any chained vehicular model should work. Let's look at the objectives we have and see if we can fit them with the train model. Objectives: * House aircraft * Launch aircraft * Land aircraft Objective 1: Housing aircraft. Adjust the train dimensions so that a single plane can fit nicely on every car of the train. Obligatory crude paint drawing: [![Train Plane Chain](https://i.stack.imgur.com/PzcBi.png)](https://i.stack.imgur.com/PzcBi.png) Objective 2: Launching aircraft. I believe we need to take a page from the soviet rocket launcher truck "Katyusha". And by that I mean we raise the the train car pad at an angle so the trajectory of the plane is to rise above the train, and then extend the platform to provide a long enough runway, which we then can secure to the ground by telescopic legs reaching down and adjusting height as necessary given any terrain. You can even temporarily detach it from the train if necessary. (Each car could have an ability to operate as an independent transporter for a limited time.) Another crude drawing: [![Planeyusha](https://i.stack.imgur.com/XOofa.png)](https://i.stack.imgur.com/XOofa.png) Objective 3: Landing an aircraft. This might be the trickiest one to pull off since the landing space needs to be straight, flat and connected, all of which we abandoned with the chained cars approach. However if each car has a portion of the landing space which can connect with each other that the car can pull out looks promising. Add the ability to position and rotate it, throw in a couple of those telescopic legs in and you've got a pretty good landing strip, even if the train is currently bent. More crude elaboration: [![Auto-Strip](https://i.stack.imgur.com/9dYhA.png)](https://i.stack.imgur.com/9dYhA.png) Terrain shown as green, landing strip parts shown in red and telescopic legs shown in blue. Once the plane has landed it can roll back or forth on the strips segments to navigate to a segment which is linked to an empty car which does not currently house a plane. After which the strips disconnect and the plane gets spatula'd onto the car platform. [Answer] The reason carriers work in the water is because water is [usually] flat so you never have to lift the carrier. On land, you would have to lift yourself over bumpy terrain, whereas on water the only terrain you might have to climb are the waves which are picking you up by themselves. There ARE vehicles which carry massive things like the vehicle which carried the space shuttle to the launch site. These beasts needed extraordinarily flat (and strong) ground to work and definitely wouldn't be able to ride up a hill. These are also smaller than an aircraft carrier. The closest you could probably come would be a long train with cars full of planes and cranes (where the cranes are to lift the planes onto the plains so they can take off). Yes, I had fun with that sentence. However, that's a far cry from an aircraft carrier. [Answer] I will not expend why a big flat vehicle is structurally challenging on land. As @Ceiling Gecko said, you need to revisit your assumptions and design a solution from scratch. What does an aircraft carrier need to do? * House people, material, and planes * Give a runway for planes to take-off and land The first question we need to ask: what does being monolithic offers us? On water, the reasons to be monolithic are easy to understand: * taking-off or landing from open waters is challenging because of waves, so we need a flat platform * transferring planes from one ship to another is impractical (even stationary, ships still pitch uncontrollably), so the same ship need to both house the planes and provide the runway However on land neither reason hold: * no need for a pre-built platform, we just need to flatten the land * transferring is easy, just have a ramp (not even a crane) and a cable (see <https://en.wikipedia.org/wiki/Tow_truck#/media/File:Flat_Bed_Tow_Truck.jpg>) So what's the solution? I would recommend a modular fleet of vehicles, composed of: * camping cars/trucks to house people and materials * a couple "big" trucks for repairing planes on the move * at least one flat-bed truck by plane to be transported * a number of bulldozers and flattener trucks, which may be transported on faster moving vehicles * add ground offensive/defensive capabilities as suited Whenever you want to have a plane take-off or land, prepare a runway, then: * for take-off: disembark the plane from the flat-bed and go * for landing: embark the plane on the flat-bed and go The only issue with this design is response time; depending on the surrounding terrain quality and the tolerance for rough terrain of the planes you have, it may require some time to prepare an acceptable fleet. Story-wise, it's good for the plot, as it means that leaving the plains for rougher terrain (maybe hilly) puts pressure on the crew. [Answer] A land based aircraft carrier has little practicality for a number of reasons. The primary reason is that equipment of that size and weight would be so slow as to be essentially immoble on land, and make a hugely attractive target. Moving large equipment already takes a great deal of planning and time, and that's with a route that is prepared ahead of time. Getting the carrier moving in the first place would require massive amounts of energy, and the mechanics of rolling on the ground would require continual energy output that far exceeds the amount of energy it takes to move a ship. A ground vehicle with the mass of an aircraft carrier would be so heavy that it could only traverse certain terrain - it wouldn't be able to climb any sort of slope nor would it be able to cross wet ground without sinking in and getting stuck. For obvious reasons, once stuck it would be practically impossible to dislodge. Finally, it would be a hugely vulnerable target. Countermeasures and mobility are the main defenses against modern bombs and missiles, but a land-based aircraft carrier would sorely lack that mobility. A real aircraft carrier can move over 30 knots, while the largest mobile equipment like the crawler-transporter moves a fraction of that speed - 1 mph. That's on a road prepared specifically for that vehicle to travel over. Also, there are alternatives such as portable airfields, such as airfields made of pierced steel planking. A team of engineers can prepare and deploy an airfield in only a day or two using modern equipment that is portable with standard trucks or even aircraft. There is also little need for a portable aircraft carrier as modern aircraft generally have the ability to operate from airfields far from the front - for all intents and purposes, with in-flight refueling the only limit to their range is the endurance of their crews. But, I suppose that if you ignore all of those downsides and insisted on a land-based aircraft carrier, you could possibly create a piece of (track-based) heavy equipment large enough to operate small aircraft - especially STOL / VTOL aircraft - off of. It would be slow and unwieldy, but it could be done. [Answer] The [Mobile Launcher Platform has a mass of only 3730 metric tons](https://en.wikipedia.org/wiki/Mobile_Launcher_Platform) - even a light aircraft carrier has a significantly larger mass (random example: [HMS Hermes of 1924, ~11000 tons unloaded, ~13900 tons fully loaded](https://en.wikipedia.org/wiki/HMS_Hermes_(95))). However, a land-based carrier could probably made considerably smaller than their ocean-faring counterparts. For example, personnel quarters, workshops, radar systems, fuel/supplies, idle aircraft and so on could travel separately by truck. Also note the strategical usefulness of a land-based aircraft carrier. Instead of bombarding an enemies base/city, simply send your aircraft carrier into it. ;-) [Answer] Large land vehicles of any kind are impractical in the real world, not because of slopes, which they could climb or drive around if you're willing to spend the money, but because of rivers. By being forced to stay within fixed boundaries they are simply not cost effective, at least not compared to an army of smaller vehicles that can cross bridges. [Answer] There have been experiments with land-based aircraft carriers. They don't look much like sea-going ones, though: they more closely resemble [a flatbed truck](https://en.wikipedia.org/wiki/Zero-length_launch). In a nuclear war, an airport is an immobile, indefensible sitting duck. Consequently, during the 1950s, a number of countries experimented with ways to make those airports mobile. The most common solution was a fighter or fighter/bomber that could be trucked around, and launched directly off the transport using extreme [rocket-assisted takeoff](https://en.wikipedia.org/wiki/JATO). By the time guided missiles made them obsolete, these launches were fairly routine. Landing is a different matter. The US Air Force attempted a carrier-style arrested landing on an inflatable mat with the [ZELMAL project](http://web.archive.org/web/20120321145417/http://www.vectorsite.net/avzel.html). This didn't work too well: the shock of landing tended to wreck airplanes and disable pilots, even when the airplane's tailhook didn't tear the inflatable mat open. If I were designing a land-based "aircraft carrier", it would be a convoy of airplane launcher/transports plus assorted support vehicles. Landing would be accomplished with portable [carrier-style arresting gear](https://en.wikipedia.org/wiki/Arresting_gear#Land-based_systems) to let me turn any short, straight stretch of road into a temporary runway. [Answer] Most of the answers here have been talking about airstrips. However, one big component of carriers is repair and support facilities. You need much more repair and ground crew than flight crew. You need ammunition, munitions, countless tons of jet fuel, expendables, parts, the list goes on. In theory, you could eliminate the need for airstrips by limiting yourself to VTOL aircraft. Whether you do that or use one of the aforementioned portable airstrip solutions, the most straightforward way to deal with the rest of it is to have a fleet of trucks, busses and RVs holding crew and material. You may also need some way to put up some sort of temporary hanger so that your crew doesn't have to overhaul the engine in driving rain/snow/darkness. This actually has a limited advantage over a carrier. If an attack is imminent, the entire operation can scatter, making it much harder to kill more than just a redundant portion of the operation. [Answer] You could pack up portable runways in trucks and fly aircraft to them. With 2 (or more) you could relay aircraft across distances greater than their flight range. [Answer] Perhaps a traditional aircraft carrier wouldn't work. I don't really know the exact details of why we don't see massive vehicles, but I assume inefficiencies get too large to sustain. However, perhaps a traditionally sized truck could hold a sort of temporary railway for the aircraft. The aircraft is transported in a truck facing backwards. When the aircraft needs to launch, the truck finds a clear length (long straight road or empty field), crew assembles a railway out the back of the truck (suspended above the ground). The aircraft then launches along the railway. Further supplies (such as fuel, ammo, and repair supplies) could be held in a second/third truck. Landing could be more problematic. One option is that these trucks don't facilitate landing, and simply launch, then pack up and head home, where the aircraft land also. Another option is that the ground crew assemble a more stable landing structure for landing (using supplies from the secondary trucks). [Answer] Before the aircraft carrier, the battleship was the queen of the battlefield. With impressive firepower and extremely thick armour, a battleship was the last word in firepower. And well, people tried to build land based versions of it. The planned nazi [Ratte tank](https://en.wikipedia.org/wiki/Landkreuzer_P._1000_Ratte) might be a good example. It was an attempt to build a superheavy tank - which by naval standards wouldn't have been very big, a mere 10,000 tons. It would have crushed bridges and not moved very fast or far. A aircraft carrier would have had many of those problems writ large. You can't really move it, can you. That said, an aircraft carrier is really a big ship designed to move a landing strip and store planes. Its designed to project airpower where there's no other way to land a plane. or is there. A landing strip is a nice large flat straight piece of tarmac. And well laying down roads temporarily is a solved problem. Have some way to level them, and your aircraft can land. While many aircraft have rough aircraft landing capability lets assume you want your fancy high performance birds landing. You want good, quality tarmac. Just lay down prefab concrete slabs, and you have a landing strip. Aircraft carriers also have catapults. Not really necessary, but you could probably build one into a large trailer, and design your prefab slab with launch rails. Add some hardened prefab containers for maintainance and you're good. If you want total mobility, you'd still need a caravan of vehicles but of a different sort. What kind of vehicle would be suitable? I'd say a modified version of a bridge layer would work. Park the vehicles end to end, connect up deployed 'runway' sections, add [emals](https://en.wikipedia.org/wiki/Electromagnetic_Aircraft_Launch_System) (maybe powered by vehicles in each segment), and launch off it. Still sounds like a crazy idea when you can have some unskilled grunts and heavy machinary just throw together a temporary landing field... [Answer] Build multiple airstrips around the area you want to cover. Include basic structures and facilities at each. When you want to "move", load critical gear and personnel into air transports, fly all your planes to the new place, and have additional crew and gear loaded into trucks and buses and driven there. It would cost a lot less, and be far more mobile. (An aircraft carrier is a floating city, that houses and feeds around 6,000 people for MONTHS at a time. The personnel are as big (or more of) a problem than just making a moving surface for taking off and landing.) [Answer] A few decades ago, Germany tried another approach to have airstrips all across the country, at positions where no airstrip has gone before. The center guardrail of freeways could be removed at short notice, turning the autobahn onto an airstrip. The autobahn section would need to unobstructed by bridges or traffic signs, of course. [Answer] There's a limited case in which it could be done: Sand. You use much of the power of your reactor to blow air down into the sand. Do it right and you can fluidize it--and now your ship can move through it much like it would with water. (Albeit slower and I would hate to think of the erosion on your screws!) I can't think of any situation where it would make sense to do in these days of guided weapons, though. In times past think of how potent a battleship would be in the Sahara, though. ]
[Question] [ The library of Alexandria was the largest and most important libraries in the ancient world. The library acquired many scrolls in its lifetime, up to 400,000, and was regarded as a capital of knowledge and learning. Many of the important and influential scholars known in history up to today took up their studies and worked here during their careers. Unfortunately, it began to decline throughout the centuries, and was finally burned down in a fire due to the wars going on at the time. In this history, The library did not burn down in a fire, but survived to the present day. Empires that came and went all decided that it needed to be preserved, and so took great pains to avoid destroying it. It was treated as a neutral ground throughout the centuries. The library was the biggest repository of knowledge and learning, but it was far from the only one of its time. Rulers and kings at war with each other would not hesitate to destroy it if it was in their interests, and wouldn't care to protect it just because of books. I need a way for this library to be preserved throughout the centuries, unmolested by wars and fallen kingdoms. How can I make this library valuable enough to be preserved? [Answer] Words have Power For much of European History during the Middle Ages, churches were seen as sanctuaries with varying degrees of effective protection. That is to say, the willingness of someone to come into a church and either drag out or kill someone hiding in there was directly related to the sense of peity that the dragger felt and the relative political value that the draggee held. In any event, the church was a place where people could go to confess their sins and worship their God, meaning that it was intended as a place of peace and kept secrets. This worked because even though the kit bag of politics contains some very un-Christian tools, the Christian faith was reasonably ubiquitous at the time and the ruling classes either believed enough to fear demonstrating the use of those tools somewhere that they expected God to be watching, or they feared the public outrage that may ensue from the same. But, if the library of Alexandria survived, it's also possible that a different religion could have come to the fore; the religion of knowledge. You can invent (handwave) the spiritual aspect of this for your purposes, but for the practical intent of your question the librarians are the equivalent of a priesthood. They do not take sides in the politics of man, are seen as answering a calling from above the needs of man, and are sufficiently organised that no king, tyrant or other form of ruler will ever get their hands on another scientific study or technology upgrade, etc. if they ever violate a single library. In point of fact, your libraries are effectively the universities of their time, much like early monasteries in Europe hoarded knowledge and scholars. If you want to take advantage of the practical improvements in technique and weapons available, you have to petition the librarians, who then choose to grant or deny your petition depending on your standing with them, which is influenced by your treatment of other libraries and the size of donations you have given to their order recently. In this sense, words really do have power and the keepers of those words wield that power in the name of the words themselves. The fact that they also have a monopoly on research and technology helps them preserve that power to be sure, but effectively the libraries act as gatekeepers between the rulers and knowledge, just as the priests acted as gatekeepers between the rulers and Heaven. If you can arrange it so that this monopoly is easy to preserve (like keeping the bulk of humanity illiterate) then you have your reason to keep libraries protected and respect their neutrality. [Answer] # Belgium was neutral before both WWI and WWII Not that it helped them much. Unfortunately Belgium is the perfect place for Europe to fight its wars and as such Europe has fought its wars in the region now known as Belgium for hundreds of years. Switzerland isn't such a good place to fight a battle, it's a really hard place from which to remove an entrenched army and the Swiss army has had a fair amount of time to get their fortifications ready. Neutrality is about your ability to enforce it, not just a declaration of it. If your library lies in the middle of the continent's favourite battleground, chances are their neutrality won't last long. If your library is high in the mountains and comes with its own army, there's a reasonable chance it might be able to remain out of the fighting. Alexandria is on the coast, a major port and gateway to the great fertile planes of the Nile valley, it's not a good place to have a library and expect it to survive. Move it either into the mountains or to a reliable oasis in the deep desert. [Answer] Because that's where their heirs are. The Library is a well-respected place of learning, with an attached university/conservatory. All of the local rulers have sent their heirs there to study, and to establish diplomatic relations with each other. Attacking the Library then leads to retaliation from all the other Kingdoms and Empires. Even withdrawing your offspring without good reason can be seen as a dangerous move. If the library is also situated on top of a mountain (like some monasteries are) then it also becomes impractical to move troops up or down. The Library is then neither a threat militarily, nor easily assailable - all they need to do when attacked is close the gates and pour boiling oil down the path, turning it into a flash-flooded river. With all of the Library defences being defensive in nature, no one can claim that the Library was attacking them. [Answer] [@Separatrix's answer](https://worldbuilding.stackexchange.com/a/170806/26637) is correct: if the library is in the way during a conquest, it'll just be collateral damage, no avoiding it. However, their solution is to move the library into the mountains or deep into the desert. However, there is a way of keeping the Library in Alexandria but "out of the way", though at the cost of geographic precision. For that, we need to look at a map of ancient Alexandria. [![enter image description here](https://i.stack.imgur.com/YFtWa.png)](https://i.stack.imgur.com/YFtWa.png) The Library was a part of the "Museum", which is in the middle of the city and near the harbor. This made it a prime target for collateral damage: even if it isn't directly hit, any nearby fire could spread and destroy it (as actually happened). So all we have to do is move the Library to another spot. My suggestion would be here: [![enter image description here](https://i.stack.imgur.com/DcEaZ.png)](https://i.stack.imgur.com/DcEaZ.png) Looking at the legend, we can see that the waterways marked as 5 and 6 are the ancient and present mouths of the Nile canal. If we handwave that away and pretend those both always existed, we effectively get an "island" separated from the city (with the west side closed off by the city walls). This "island" is a useless target during a marine attack since it's nowhere close to the harbor, so it wouldn't be used by defenders to mount a defense. In the case of a land-based assault, this flank of the city is incredibly defensible: attackers would need to either cross the exterior canal (6 on the map) or get funneled into the Library's walls (which, agreed, would be bad for the Library!), get past the walls, and then cross the interior canal. Much easier to attack the eastern walls. So, with the exception of the case where attackers decide to funnel themselves over the Library's walls, it should be safe from any direct fire (especially if you change its architecture to make it a bad defensive position, so defenders aren't incentivized to make a last stand there). And then we just assume that attackers simply always agreed that any attack from the West flank of the city was suicidal and never attacked from there. Lastly, all you have to do is make the canals wide enough to work as fire-breaks, so that if the city is on fire, the Library is safe. --- Obviously, this solution is hardly perfect: putting the Library so close to the city walls makes it quite vulnerable to attacks on that flank, especially if attackers decide to dam the canal far from the city, eliminating most of the defensive advantage on that side of town, transforming the waterways into poorly designed dry moats. You can either pretend that never happened or change the canal into an actual powerful river, too hard to dam with ancient tech. [Answer] The entire city burned to the ground, all of it...except the Great Library. It stood in pristine condition, the only uncharreted building in miles. It was a miracle, and it was obvious the the library and its vast knowledge were touched by the Gods. The legend spread fast, and soon in every town and city the legend is heard "The gods protect Alexandria", and for kings it becomes wise not to dare attack or come even close of it with conquering intentions, since for a human king another is a rival, but to fight a god is a lost cause. Every baron, emperor and even foot soldier knows that. But that is not all! the Library becomes gradually a site of pilgrimage, increasing with the passage of time. It's like the Mecca, but for scholars and wise men. [Answer] You put the key point in your question already: > > Rulers and kings at war with each other would not hesitate to destroy it if it was in their interests > > > There's pretty much no practical benefit to burning down a library. If there are no soldiers there, no resources there, no grudge there, then there's no reason to take the fight there. You could even think of the library as a sort of trophy. Regardless of how often the thing is fought over- keeping it in good condition is a sort of world-wide pissing contest to prove that you're the elite army of the time period. "Yeah? I could take that city and with three less burned books!" [Answer] Following @Separatrix comment. I will add Principality of Andorra. * Surrounded by mountains with difficult access. * Can't be used to cross the mountains easily. * Nothing worth pillaging. * Good vacation place for the elites of surrounding countries (elites will push against anything that might ruin it) * Joint government by both countries that border it * No other nearby countries that could remotely be interested on conquering it * Indirectly under protection by Rome's Pope, and surrounded by countries that respect Pope's authority. * Ethnical, linguistic & historical links with surrounding countries * Used for contraband, which is then bought by elites (during Franco's dictatorship, it was a way to get many goods that were lacking in supermarket's shelves). If independence is lost, you lose access to all contraband [Answer] ### Custodians of Ancient Knowledge You have to build a sacred Order, composed of dedicated intelligent men, which mission is to guard and preserve the knowledge. While discussing and promoting to world leaders the neutral grounds of your library, as a solution for all knowledge, you must have this neutral and independent group of people who, under no other authority except themselves, guard world's knowledge. [Answer] Make the library a holy place. Though not a library, the unmovable ladder in Jerusalem is a great example of what you're aiming for. Several different religions fought over the church the ladder resides in, and to prevent further conflict they came to the solution that nothing be changed. A ladder was left lying around, but no one dares to move it for fear of a religious scandal. Obviously with your location being a library the unchangeable aspect of the situation would have to be removed, but the rest could be a plausible explanation. [Answer] I suggest that you take a look at Larry Niven's Known Space series. In that series, there is a race called the Pak, who are constantly engaging in what is essentially high-tech tribal warfare. Due to the destructiveness of their weapons, they would lose all their tech after each war. However, they always managed to rebuild quickly, as they had a huge library that they put all their knowledge in. Occasionally one clan or another would try to take the Library; however, doing so provoked all of the other clans to genocidally kill off that clan. [Answer] The main problem you have is that if you want library to change hands often (as it seems from the question), it is incredibly likely that one of the parties will want to burn it down. For example, conqueror doesn't want to destroy the library so they could learn from ancient scrolls or profit from scholars coming to their city ... but then defender might want to ruin it just to prevent that. Or make a last stand in the library itself. You can try to introduce religion or whatever else, but throughout history it didn't work all that well - the only religion that really exists is power and wealth, and it isn't compatible with peaceful change of ownership. So the most realistic solution might be that the library itself is never captured, just the surrounding area is. There are tons of solutions, like islands, mountains etc. I am partial to mesas, they look mythical and therefore very suitable for the mega library. The library is on a huge mesa and is self-sufficient (at least with water, and enough food storage to last several years). A single narrow path leads up from the city below the mesa. Path (and all mesa edges) is heavily defended by the library military while the library is in the middle of the mesa, few kilometers away from the edges. Island is a viable solution too, and it doesn't require a large change of Alexandria landscape either. Put the library on a large self-sufficient island, few kilometers from the nearby city. Use whatever fortifications are required to prevent invasion. This is much harder to defend and library would fall to a massive invasion (mesa and mountains might not), but nobody would waste half their fleet to get library admission fee when they can already get almost all of the tourism income from scholars staying in the city. [Answer] The Library is knowledge. All other legal libraries are part of it and under its protection. All empires must come to deal with the library to content with an ever changing world. Some come to figure out how to grow better crops, or what they can do to prevent their crops from failing. This resource is becoming hard to get (say sulfur), is there another source or can it be replaced (depending on requirement charcoal?). As The Library know's its position of power, they make sure to guard it. If they become under attack ever again, they will again destroy their knowledge, leading all to suffer. So of course in history this has to have happened at least once, and the results dramatic enough to ward off future attacks. [Answer] # The library is sitting on top of a gigantic bomb of greek fire It is operated by an angry order of suicidal priests deeply devoted to the knowledge deity, to whom the maintenance of the quiet, contemplative and stimulating academic environment of the Library is a matter of paranoid holy devotion. It wasn't always like this. The Sacred Order of the Pen and Compass has been maintaining academic grounds around the known world for centuries. They have always done as they were asked, diligently dissemitating knowledge and learning. Monarchs and Commanders came with them to design engines of war, to break cyphers and to accept their children as temporary disciples, so that they may walk amidst the learned men of their time. And the Order acquiesced many times, only wanting for its holy sites and doctrines to be respected within their sanctums. Nevertheless... Many of them has seen their share of libraries being burned and sacked, brothers being slaughtered and violence desecrating their holy sites. Often by the operation of the very engines of war they helped created, on the hands of the very heirs they allowed in their midst. Irritated that the holy sites were acceptable collaterals in the conflicts brought by the mercurial environment of allegiances in the ancient times, Artorios, The Mad, then the Grand-Master of the Order, decided do something about it. He ordered the High Priests to plant gigantic, huge ass, crazy big bombs at their respective holy sites, the schematics of which were devised by Artorios himself. Any whiff of fire so much as touched library walls, and the Head Priest of the site was required to activate the bomb, and to send the city into oblivion. Any hint of violence comming their way, and once again the armies, commanders, the city and anything in the blast radius goes into gas phase. The order went through troubled times as it shifted the attitudes and training of their priests to suit the new directive but eventually it became much more paranoid, suicidal and obssessive about neutrality. Only the top tier ranks of the priesthood knows about this. So how come the kings fear this information, if they do not know what is going on? Well, In the past the Hungarian library of the same Order was caught at the wrong side of an invasion and Hungary had to change its capital and most of its government officials... But the world gained a new hole. So people with armies started to care whether or not they would piss these priests off. [Answer] International Laws The neutrality of library buildings (and similar heritage) can be achieved with international laws and the laws can be enforced by a powerful nation/organization. However, in real-world, regulation of protecting cultural heritage during war times emerged in the middle of the nineteenth century. It would have been more difficult to enforce rules in olden times. Additionally, even the laws didn't prevent of the destruction of libraries. Here is a relevant excerpt from the book The Settlement of International Cultural Heritage Disputes (By Alessandro Chechi): > > ...The latter treaty proclaimed that museums, monuments, and scientific and cultural institutions were to be considered as 'neutral and as such respected and protected by belligerents'. Article 56 of the Regulations Respecting the Laws and Customs of War on Land annexed to the 1907 Hague Convention (1907 Hague Regulations) declared: > > > > > > > 'The property of municipalities, that of institutions dedicated to religion, charity and education, the arts and sciences, even when > > State property, shall be treated as private property. All seizure of, > > destruction or wilful damage done to institutions of this character, > > historic monuments, works of art and science, is forbidden, and should > > be made the subject of legal proceedings.' > > > > > > > > > Moreover, Article 23(g) established that, during hostilities, monuments and buildings dedicated to art and science ought not to be attacked or bombarded, unless necessary for military reasons... > > > Unfortunately, these coded norms did not prevent widespread damage and destruction during the two world wars, such as the destruction of the Rheims Cathedral, the burning of the library of Louvain, and the bombing of Dresden and London. > > > Mountain Vault Or, just store the archive in a mountain vault with granite rock guarding the tunnels from above. For the modern version, there can be reinforced entrance doors that can able to withstand a nuclear blast like the "Granite Mountain Vault": [![enter image description here](https://i.stack.imgur.com/Kx3Ffm.jpg)](https://i.stack.imgur.com/Kx3Ffm.jpg) [![enter image description here](https://i.stack.imgur.com/p7sHhm.gif)](https://i.stack.imgur.com/p7sHhm.gif) > > Since 1965, Granite Mountain has safeguarded the Mormon Church’s genealogical library. The library is buried 600 feet beneath the mountain, where it contains 3.5 billion images—from census records to immigration papers—on microfilm... The facility is naturally climate controlled, but is also protected by armed guards and a 14-ton, nuclear-blast-resistant door. Chances are, somewhere inside, there’s a record with your name on it. > > > <https://www.mentalfloss.com/article/31219/9-worlds-most-ridiculously-secure-safes-and-vaults> > > > [Answer] All the answers here are missing an important point, some are also incorrect stating that the Library had no military value and that there wasn't a good reason to destroy it. But the truth is that the stronger the culture of a people the more difficult it is to subjugate them. A lot of times conqueror decided to obliterate in one way or the other the culture or the conquered people. A lot of times the capitals of the falling empires were razed to the ground. This is the most straighforward way to weaken their resistance. There have also been cases of conquerors with strong culture who decided to take nonetheless the tough approach like the Conquistadores who obliterated the Aztech culture. The Romans didn't destroy the Greek culture because they had a different approach. The colonists placed in big numbers represented the iron fist, but they also had the velvet glove of liberal policies toward the conquered people. They were so much open minded that eventually they ended up saying Graecia capta foerum victorem cepit. But the Romans were an exception most of the other people took a different approach towards the people they conquered. Your hope of saving the Library falls on the case of several open minded conquerors in a row which is unlikely. A possible solution might be a library placed by an earlier conqueror containing a culture not appreciated by the local people. [Answer] We already have a library like that: The Vatican library. It's just very, very closed and very, very specialized. Imagine if it wasn't. ## The dominant religion cares about knowledge Which is to say, the dominant religion isn't frightened by scientific discovery nor broad propagation of knowledge... but instead embraces knowledge wholeheartedly. Which means they're good librarians. ## The dominant religion is politic enough to stay out of wars They recognize the secular powers and "let them have their little wars", but glide above them. They focus on being beloved by the citizenry, and an instrument of faith, even to the Reformation types. Take the Vatican, which is the bastion of Catholicism, the opposite side of the religion from the various Protestants. * For 500 years, from [King Henry VIII](https://en.wikipedia.org/wiki/English_Reformation) to [modern Northern Ireland](https://en.wikipedia.org/wiki/The_Troubles), no battleground between Catholics and Protestants has been more bloody than Great Britain. The Royal Navy and Redcoats concurrently had the ability to project power [anywhere in the world](https://en.wikipedia.org/wiki/British_Empire). Yet no move was made against the Vatican. * Even Germany, crucible of Protestantism and home of Martin Luther, [notably incompatible](https://en.wikipedia.org/wiki/Kulturkampf) with Catholicism, their most hateful government [made their peace](https://en.wikipedia.org/wiki/Reichskonkordat) with the Vatican and [left them alone](https://en.wikipedia.org/wiki/Vatican_City_in_World_War_II) while sacking Rome. That's the power of religion and diplomacy. ]
[Question] [ I'm creating a humanoid species, roughly based on humans. The difference is that not every opposite sex couple of fertile age could produce offspring. The premise of my story is based of some men being incompatible with some women. And I mean genetically, if they mate they won't be able to produce children. Is this possible? And is there something similar in the nature, it doesn't have to be in humans. [Answer] Yes, this is possible and in fact already happens in humans causing apparent infertility in couples (alongside a host of other sexual reproducing organisms). Consider for instance variations in two genes encoding for proteins in the eggcoat, ZP2 and ZP3, and another gene encoding for a sperm protein that latches onto the eggcoat, C4BPA. Each of these three come in various, in themselves stable and viable, forms, but the end result is that a male with one form of C4BPA cannot produce offspring with women with particular forms of ZP2 and ZP3 because the sperm fails to latch onto the eggcoat because of shape differences of the proteins. See [here](https://www.sciencedaily.com/releases/2016/01/160106092026.htm) for details. That said, the woman and man may hedge their risks through things like polyandry (having sex with more than one man) or polygyny (having sex with more than one woman) and this in fact does happen in apparently strictly monogamous relationships. Other mechanisms are at play here too, see for instance [The evolution of polyandry II: post-copulatory defences against genetic incompatibility](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1688229/pdf/RCYHMFN2TP209YMR_264_69.pdf). [Answer] Something similar is possible in humans due to a difference in Rh blood groups. > > The Rh blood group system consists of 49 defined blood group antigens[1](https://en.wikipedia.org/wiki/Rh_blood_group_system), among which the five antigens D, C, c, E, and e are the most important. > > > [A]ntibodies to the Rh(D) and Rh(c) antigens confer significant risk of [hemolytic disease](https://en.wikipedia.org/wiki/Hemolytic_disease_of_the_newborn) of the fetus and newborn. > > > (from [Wikipedia](https://en.wikipedia.org/wiki/Rh_blood_group_system)) > > > In short, the egg and sperm of Rh incompatible people can produce a living fetus, but antibodies of the mother attack the blood cells of the fetus which often leads to the death of the fetus if not treated. Please note that in humans this mechanism takes effect only after the first pregnancy. The first child is born healthy, but after that most or all pregnancies end in miscarriage or the children dying shortly after birth. Since you create your own species, you can adjust the mechanism so that even the first child of an incompatible couple dies. [Answer] See also the [white-throated sparrow](https://en.wikipedia.org/wiki/White-throated_sparrow) that had a gene mutation that has, effectively, created four genders. There are still the standard "male" and "female" sexes, but a separate gene also drives the nesting and young rearing behaviors. Offspring are genetically viable with off-pair pairings. However, due to the behavior drivers, the offspring don't survive as the pair needs a matched set of opposites: aggressive and territorial vs. nest-watching. Two agressive types don't sit on the eggs. Two nest-watching types fail to fend off predators. See [this article](https://www.audubon.org/news/the-fascinating-and-complicated-sex-lives-white-throated-sparrows) for more details that I might've forgotten. As a result, the behavior gene is starting to drive phenotypical differentiation, so you get α-males and β-males looking different so that they can be identified by their counterparts: the β-females and α-females respectively, which also have phenotypical expressions for the same reason. In a few million years it wouldn't be unexpected for α/α or β/β pairs to be genetically non-viable (in the same way that male/male and female/female pairs can't reproduce) in the way you're looking for. [Answer] Another way for this to happen is a [ring species](https://en.wikipedia.org/wiki/Ring_species). Essentially you have a bunch of subspecies, each of which is similar enough to the one next to it to allow interbreeding, but the ones on the ends have diverged far enough from each other to make them incompatible. [Answer] Yes, that is possible. Rabbits can have a dwarfing gene, which leads to a smaller animal. Two of these genes are lethal. See: * <https://en.wikipedia.org/wiki/Dwarf_rabbit> * <https://en.wikipedia.org/wiki/Cuniculture#Genetics> [Answer] Absolutely possible. See reference: Homo Sapiens. There are many genetic incompatibilities that prevent offspring, such as incompatible blood group, guaranteed-lethal recessive gene defects, etc.. [Answer] And this is actually the way evolution works in creating new species. Eventually a group of individuals (a subspecies) emerges that is no longer able to reproduce with all other individuals of the species. And as over time the group of individuals they are not able to reproduce with becomes gradually larger the more you could speak of them as a new species. This is something that happens every day. Slowly, on a small scale in every species. It is more of a question how likely it is, to be exactly at that point in history where a species is about to split into two no longer compatible sub species. It is not impossible, but also not likely to happen more than once in 100K+ years. ]
[Question] [ Let's say that due to some intricate societal laws and advanced technology, people were allowed to nominate someone for a "judgement". This person who is nominated, is usually someone who is terrible; the likes of people who trample on the less fortunate to have their way (in politics, business or even social life). If the person is deemed unworthy, then they are immediately transported to a harsh planet, which is basically a death sentence. Now what would happen is someone, let's call them John, starts being a real a-hole. Wants to make a lot of money and become famous, and doesn't care what happens to people who are affected by his poor decisions. Someone who makes his business by creating a dangerous drug which he advertises as safe and harmless. He also creates a much needed drug which is only available overseas, he charges three times the amount. This happens all the time, but this particular person keeps on standing by their choices and just says "business is business", "I do it because I can" or "I can't hear you over these piles of cash I have". Society just gets tired of his ways, and decides to nominate him for judgement. He presents his case in an open, online-based trial and anyone in the world who would like to, decides to vote. If the votes are for him, then he goes on living whichever life he chooses. If the votes are against him, then he is sent to this undesirable planet. How would people in the world behave if people could vote to send you to another planet? Rules/assumptions: * All normal laws (International and Domestic) are valid and are the same as the current state and take precedent + So if you were to murder someone, and were dealt with by the normal law, then that would be that, you can't be nominated for that reason * A "nominee" needs a sufficient amount of nominations to be up for "judgement" in a fair manner * Anything you say or do (online, or physical) can be used for or against your case * A majority vote (even by one vote) is binding. A tied vote is in favour of the nominee * You cannot be nominated for the same reason twice (double-jeopardy I think it's called) * Due to intricate systems, it is impossible to rig or bribe the votes/voters (voting is 100% honest and accurate). [Answer] You don't have to rely purely on hypothesis to answer this question - we have an historical example of behaviour quite similar to this: Ancient Athens. The process of [Ostracism](https://en.wikipedia.org/wiki/Ostracism) (from which we derive our modern usage of the word) was one where citizens of Athens could vote to exile anyone for a period of 10 years. This was part of their democratic system for about 100 years. People didn't have to specify a reason for wanting to exile someone - the assembly would be asked if they wanted to hold an ostracism, if they voted 'Yes', then the Ostracism would be held, where people could vote against whomever they wanted (there was no 'nominating' process), and the person with the most votes against them would be exiled if they got more than 6,000 votes. (Note that the number of citizens in Athens at this time was about 30,000, voting wasn't mandatory, and there could be any number of candidates for exile, so 6,000 is actually a rather high bar). Initially, it seems to have been used as a safeguard against tyrants, but there is evidence that people voted against people for all sorts of reasons - in particular, there is the story of Aristides "the Just": > > Now at the time of which I was speaking, as the voters were inscribing > their [ostraka](https://en.wikipedia.org/wiki/Ostracon), it is said that an unlettered and utterly boorish fellow handed his ostrakon to Aristides, whom he took to be one of the ordinary crowd, and asked him to write Aristides on it. > > He, astonished, asked the man what possible wrong Aristides had done > him. ‘None whatever,’ was the answer, ‘I don't even know the fellow, > but I am tired of hearing him everywhere called 'The Just.'’ On > hearing this, Aristides made no answer, but wrote his name on the > ostrakon and handed it back. Plutarch, Aristides 7.5-6 > > > One could probably draw a modern-day parallel with Brexit voters, many of whom seemed to have voted for it for reasons that had little to nothing to do with the EU. [Answer] ## A weapon of mass destruction What you're doing here is giving people the ability to kill off anyone they choose, for any reason and completely legally, just by majority vote. That's pretty huge, and would certainly result in a different society than what we have. It goes against many beliefs we have today. Democratic nations wouldn't like it because you're taking away rule of law and replacing justice with rule of the mob - if enough people think someone should be punished with this then they will be, guilty or not. Undemocratic nations wouldn't really like it either, since the will of people now overrides whatever way they have of keeping in charge. No modern government would really want this, at all. You didn't specify what society is like before this (except "advanced technology") so I'll assume something similar to present day as a starting point to see what would change. ## Politics There are two ways of being more likely to be nominated: being known by many people, and being more disliked than liked. First off, politicians and world leaders would be big targets. Think Putin's Russia is being too imperialistic? Don't like what direction Erdogan is going with Turkey? You think this newest presidential candidate would be the worst thing that ever happened to America? Congratulations, you can nominate them. You'll probably win too - it's pretty easy to quickly rifle up a group of angry people to vote your way and you don't need a majority of all people, only of the people who care enough to vote. After a while you would settle in with a new kind of world leaders, ones who are safe, likeable, nonthreatening and play to what the people want so that don't get nominated. These people might not really be in charge though, but instead puppets for the people who really rule the countries and are smart enough to stay in the shadows. So what looks like a tool for democracy might lead to a less democratic world. ## Fame The second big target after politicians would be celeberties. Couldn't you imagine 4chan making a raid to get Justin Beiber voted off? If they failed, they can just try again later - they can just make up a new bullshit reason every time. And they only have to succeed once. If celebrities stay in this new world, they will probably want to stay local or anonymous. Even today anyone even remotely famous receives tons of death threats and abuse - if it becomes so easy to make good on the threats with no repercussions, it might be even less worth it to be famous than it is today. ## Religion A thousand people sounds like a lot, but it really isn't. There are estimated to be about 25 000 scientologists in the US, and they have a history of mobilising their members for propaganda, information control and other creepy business. They could certainly set up constant nominations of anyone they consider an enemy, opposition or a traitor. Many votes would probably fail, but with persistence some would not. When some pass, there starts to be a huge incentive to not go against the church of scientology. And there are many other cults around with thousands of members who could do the same thing - or new ones could be formed. Then of course there are more mainstream religions. These tend to be more sensible, but they also have much larger memberships and usually have fundamentalist branches that claim to speak for all. What might they encourage? I don't know, but we would soon find out. ## Summary I don't know exactly what kind of society would think this system would be a good idea and implement it. All I know is that it would be very different from ours, and I wouldn't want to live there. [Answer] A lot of people here seem to be getting caught up in judging the system rather than answering the question: How would people in the world behave if people could vote to send you to another planet? People in this society would probably pay very close attention to their public perception. Marketing and PR would be very important, even to moderately notable individuals. Making sure that your every action is either seen as good or not seen at all would be important, so you can bet there'd be less transparency all around. Some few people, usually survivalists, counterculture extremists, and brazen criminals, would actively seek to be exiled, for various purposes. It would be possible - and people would very likely do this - to game the system by acting when the public attention is focused on someone else. If someone else in a high-profile case is going to judgment, then you are freer to act nasty in their shadow, while no one else is paying attention. This already happens in the real world, where politicians and companies are known to take advantage of dominating news cycles to take actions that they feel should avoid public scrutiny. The public referenda would provide one more such distraction. It would also be the case, given the low 1,000 person requirement for nomination, that relatively small special-interest groups would dominate politics. This program of judgment would provide such groups with a mouthpiece for expressing their dislike of an individual - even if it were extremely unlikely that their nominee would actually be sent into exile, they would still nominate them to get the stain of that ignominy on their enemy's good name. This would also be used by the public, when whipped into a frenzy, to serve the people's justice when the courts didn't - OJ would have been exiled, as would many of the police recently entangled with the BLM movement's wrath. Which leads me to my final point: after a while, this would cease to have the stigma that you'd think it would. Given the relatively low barriers to its use and abuse, the whole system would eventually be something of a trial by fire and really kind of a grotesque "vetting" of any political or pop culture figurehead. What's really interesting is what happens to the planet of exile after long enough. Do you get another Australia? Depending on how hostile it is to human life, you might. Or do you get, perhaps, a monstrous boneyard, a giant planetary tomb which journalists investigate on tip-toe in their efforts to discredit the system - or do you get a cultural blind spot - a place and concept so horrible nobody wants to talk about it or acknowledge its existence - a death sentence, carried out without due process of law, able to strike down infants and old men as equally as criminals with blood on their hands, a brutal enforcement of social norms by reign of terror? [Answer] I think one of the big problems with this idea is that pretty much anyone who is well-known will have a significant amount of people who hate them - and in some cases may gain more haters than those who would care about them enough to vote in their favor. Doing anything interesting or notable will be risky business in this world, so the world might wind up more boring overall. Politics might actually improve though. In our world, politics is as much a matter of knocking down other candidates as it is boosting your own. Spread enough hate, and swing voters will start to see both major candidates as being terrible, only choosing one to keep the lesser of two evils out of office. If gaining enough hate in the public eye (regardless of how people view you relative to your opponent) means being shipped off to Space Australia, slandering opponents - and being slandered yourself in retaliation - carries a much greater risk. Politicians would have to focus on their own positives instead of their opponents' negatives. [Answer] Lets accept the voting system as valid and working. I would suspect that after a given length of time society would collapse. Technology would progress at a slower rate, and most fields would become stagnant. Here's the why: In our society today, we have what I call the "greater moral range" that is a narrow band of moral decisions and topics that everyone can agree on. That "greater moral range" is actually quite small. It changes frequently, but is important. It's the scope in which you can do "things" with no side effects. Then you have the "normal moral rage". That is the range of things that are considered at least moral enough, that no one cares enough to make a big stink over, or at the very least, can go "well they are wrong but it doesn't effect me", or "different strokes for different folks". This is a very narrow band as well, but it's generally tied to some form of geographic area, or religious belief. Maybe country or region. Third is the "lessor moral range". This is the area that people think your doing something wrong and will actively try to stop you. This is a wider net, but still, general pretty narrow. Last is the "outer moral range". This range is the wide one. This is for the actions and decisions that are just wrong, and everyone can agree they are wrong. Now lets take some examples. Please excuse the harshness of them. 1. You should beat your wife daily. Today, not a good thing, 200 years ago, normal. So is that really where you want your society to stay. Keep up the wife beatings, or you will fall into the lessor or outer moral range? 2. Slave owning is fine. Again, 300 years ago, it was not only "ok" but you were doing your slaves a service. Anyone that spoke out against that or worked against that idea would have been in the lessor, or outer moral ranges again. 3. Kill all Jews. Now, obviously we think this is a bad thing, but time and time again in history, we see this as a common theme. And not only is Jewish killing OK, but working against it was thought of as unmoral. 4. Human rights. We now think of human rights as a good thing, but there was a time when that wasn't so. That suggesting that you feed your enemy, don't boil the heretic in oil, don't flay the thief, etc, would have gotten you dead right beside them. The point is this. Our morality evolves over time. Things that we now think of in the outer or lessor moral ranges were at one time, core beleifes and part of the greater or normal moral range. What would happen if you just started teleportation the people that the "crowd" didn't agree with to another planet? Well then our greater moral range would never shift. We would never better our selves. Remember that all great leaps (and even the small ones) start with some "jack ass" standing up for what they believe in. Be un-moving in their convictions, and standing their ground no matter what. If you could just teleport those people off the planet, then we would never grow. Things would never change, and our society would just become stagnant. [Answer] I think it would be much easier to abuse than you would like - and correspondingly, the behavior would alter in favor of those more ruthless, not against them. Joe would probably be much better able to send to the other planet, those who object to him, rather than the other way around - which means more people would act like him, and fewer would dare to object. So, first, you need someone to keep track of what is an exile-worthy offense or not. What those factors are, and how they're portrayed, is going to be very important. There's lots of historical precedence for people judging, with harsh penalties, "moral" values that do no harm (personal preferences like sexuality or religious beliefs) over "practical" values that do a lot of harm (practices like exploitation in the name of business, or socially common abuses). It probably won't take much before people are exiling for "being different" without harm, and leaving be those who cause harm in expected ways. Next, there will be a really, really clear power differential based on online presence. After all, the trial depends on whatever is being said online about him, and the online doesn't really have a mechanism for being verified as truthful. Joe, with his lots of money, can fund a big website devoted to his charitable acts (whatever they may be), and populated by his friends, acquaintances, or yes men. He can fund a genuinely useful or popular site, and use it to spread bits of pro-Joe propaganda. He can fund a few online rants, through proxies against some person who's questioning his practices, and make it look like they're persecuting him or others who are successful in business, this person has a grudge, they're being mean. So, someone who is quiet and minding their own business, will not have a strong online presence to debunk any claims made against them. Anyone who does have a strong online presence, will have people for and against them, people who think the world of them or hate them - its human nature to polarize. A few big, showy, well trafficked pages (something which, unfortunately, money can manipulate) can swing opinion about somebody in a big way - especially in a very large community (all of online-world), where people who actually know the person are very, very few. And, even at the very worst, it can be easy for Joe to swing up enough dirt about whoever is complaining about Joe, to make it look like an argument, opposing viewpoints, and mutual antipathy rather than "Joe is being a real jerk" - which can derail the voting-for-exile process altogether. What process is there for verifying things attributed to a person are really from them, especially online actions which use screen-names? Joe can deny that the nasty rant posted under a similar screen-name is his, or can fake up a nasty, obviously biased, anti-Joe rant under an opponent's screen-name to undermine their credibility. What process is there for verifying that nominations are made by people with a real or even personal grievance, instead of people who find a ranting webpage, take a side based on the clever portrayal of one-sided or biased information, and bounce over to fill the nomination forms without verifying what's going on? And, finally, once you have your thousand nominations - who gets to set up the voting process, and what information is given, in what priority? Does the page list the person and grievances against them first, does it have a space for the person's defense, does it show the votes for and against (people tend to vote with the "winning" side - so an early imbalance, even if not based on factual evidence, can influence a swell in public opinion and manipulate the voting). Does it rank these kinds of resources by how much they're verified, how much they're viewed, what kinds of things they directly said or participated in, or what things other people are saying about them? Does it include the context and behavior of the accusers? Context is key. Context is key. And online presences can be manipulated in a lot of ways, both legitimately or covertly. The voting will not decide whether the person is exiled to another planet or not - the process for deciding what context will be used to show Joe's life and character, and the grievances against him (and the actions and characters of his accusers) will influence the vast majority of people into voting one way or another. The contributions from those who know Joe and are themselves for and against him, and the contributions of those who carefully researched and weighed the evidence and judged him - are both going to be overwhelmed by the huge numbers, the majority of the world's population who haven't met him, and don't really know what's going on, but are influenced by popular opinion and the context in which he is presented. Just take a look at online witch hunts - proof is a lot less important than how something can be made to seem. [Answer] Look up ancient Athens Greece. They had thing called Ostracism where every year it was asked if the citizens would like to banish someone. If the answer was yes a vote was taken and if certain voting requirements were met the "winner" would be banished for 10 years after having 10 days to wrap up their affairs. [Answer] Ok - first Problem: There would be thousands of votes each day. If you need only 1000 people to nominate someone, there would be endless nominations - and who has the time to do a thousand votes each day? Imagine a single appeal would take 5 minutes to present the accusation and 5 minutes for the defence. So a single judgment would take at least 10minutes of my time, if I want to read anything about the case, the people involved and background info to cast an informed vote, I would need at least an hour or two. That means a normal busy adult simply wouldn't have the time to participate fully in a lot of votes. What if someone from china is voted on in the middle of the night? I don't even speak chinese, but I could vote on him, couldn't I ? So the result would be that most votes would come from a big mass of people who don't take the time to read anything about the case, but just cast random votes or all yes/ all no on all votes which are open that day. - So whatever the accusation the random worldwide voting could lead to any verdict and will have much more power than the informed maybe 10.000 votes who have actually read the case-file. Now lets see our current world - there are a lot of people who feel strongly against the death penalty, I think a lot more people then there are people who like to randomly destroy or see people get killed. - If there is only one pro-life activist in every 10.000 People on the world in a population of 8billion. That would be 800.000 pro-life activists in the world, who would just vote "LIVE" on every vote worldwide. I think almost no one would get exiled in the end. [Answer] Appealing to the "lowest common demoninator" of your peers = optimal survival strategy. Whatever one would do to get the highest voted comment on a YouTube video or Reddit comment feed, is now analogous to what behavior you'd have to do to not get "downvoted to Planet Rubbish." Except, YouTube comments / Reddit are slightly above average in terms of population, so, who knows. For your story, it might require everyone become really nationalist so they don't get "downvoted to Planet Rubbish for not going along with 'if you don't like Dudestan or go back to where you came from!' -- which maybe Corporate Media would successfully have marketed... unless somehow Corporate Media got "downvoted to Planet Rubbish" for promoting nationalism. But let's be realistic ;) [Answer] Since there were several great answers to the question, I will just add my 2 cents, and some questions for you to think about. For a judgement in world-wide scale, a nomination of 1000 is too low. Supposing that radical (and rabid) minorities, which could nominate a person just because he/she is "the enemy", can be about 1% of a population, a nomination should require at least that many votes: about 70 million these days. People that have that much popularity would have to be very careful about all they say and do, or not be popular anymore: anything can spark the flame of haters. Since common crimes aren't cause for nomination, what actions, precisely, are cause for nomination? On what laws they are written? Do all countries agree on what are these actions, or it depends on the social mores on each country? What is the standard of evidence for/against the nominated? Is hearsay ( valid as evidence? Who presents the evidence for the voters to examine, and how? Can someone check that the voters actually examined the evidence? [Answer] This is not a complete answer, just some more consequences. As @coteyr points out, social progression will essentially end. Furthermore, anyone who is famous in some way will easily have 1000 people who dislike them, regardless of how "likable" they may be. Whether or not they'd be voted off or not doesn't change the threat of being nominated, which would certainly curb some people's quest for fame. As an example, consider the presidential nominees for any given countries election. Do any of them have a majority of the vote for acceptance? Would those opposed be willing to use banishment to remove the opposition? We can also assume that (especially with such a low threshold for nomination) that there will be far more people nominated than society at large could vote on. So one of two things would happen: 1. Enough of the population would stand up against banishment by generally voting "no" on any banishment, whether they had information about it or not. 2. Banishment would happen on a localized level with a number of votes cast that is proportional to the number of people effected. If #1 does not occur, then non-famous people will be banished with a small number of votes. If that's the case, then you are almost guaranteed another consequence, which is that underground businesses will arise that will sell banishment votes so that those with enough money can banish anyone they please. Which will then setup a protection racket as well, where people can buy votes to keep from getting banished. Consequence? People would earn income off of selling their votes (even if illegal, this would be near impossible to track or prove unless you vetted all votes to ensure they had some connection to the actual person involved). Consequence? Those with money would be able to "shape" society by banishing anyone against them, though over time this would actually have the interesting effect of flattening out income across the population through redistribution of wealth. One last thought, if banishment continued to occur and whittled away at the population, if there was ever a group that achieved majority status (such as a religion), they could simply vote everyone else off the planet. Though one can presume that there would be a revolt before that occurred. Interesting question - and not that far from the current society that many modern countries find themselves in since democracy abounds and by voting on our legislative and judicial branches we are effectively (indirectly) voting on who is banished from society. [Answer] # A lot of people would die Anger tends to elicit action than peace/indifference/compassion. You are more likely to rage out a one-star review for bad service. You are far less likely to leave a 5-star review for good service. A large number of angry people would downvote people (pretty much every politician ever will die). A small number of happy people will dedicate time defending others with their votes. [Answer] I don't think there's validity to your question, simply because there is absolutely no way on this Earth that voting is 100% honest and accurate! There will always be some guy voted against, who happens to be the son of some duke, that magically ends up not being exiled!! There will always be the ones with the power and the people. And where there is power, corruption inevitably follows. ]
[Question] [ In my fictional world, there is a race of mermaid-like creatures that are having a bit of a problem. That problem is that the surface dwellers have made something called a depth charge. This makes underwater explosion that creates pressure waves that crush their lungs. So what I’m wondering, is if there is any way (aside from swimming) to protect against underwater pressure waves? This race has advanced biological technology from breeding and growing their tools. It is at the point where they have taken a dolphin and breed everything except the sound organ to non-existence and turned the rest into a sound gun. [Answer] Bubble curtain. [![bubble curtain around oil rig](https://i.stack.imgur.com/3c9Wk.jpg)](https://i.stack.imgur.com/3c9Wk.jpg) <https://www.eurotrib.com/comments/2012/9/6/165418/5127/3> Depicted - an oil rig with a circumferential bubble curtain to reduce underwater noise. <https://en.wikipedia.org/wiki/Bubble_curtain> > > A bubble curtain is a system that produces bubbles in a deliberate > arrangement in water. It is also called pneumatic barrier. The > technique is based on bubbles of air (gas) being let out under the > water surface, commonly on the bottom. When the bubbles rise they act > as a barrier, a curtain, breaking the propagation of waves or the > spreading of particles and other contaminants... > > > It can be used for the following purposes: to reduce propagation of > shock waves (e.g. acoustic waves from engines or pile driving,[1](https://i.stack.imgur.com/3c9Wk.jpg) > explosions etcetera)... > > > Your mermaids need some tech to produce gas. If they can breed dolphins into handheld squeak guns, making bubbles should be within their abilities. You could ferment things, or tap deep methane deposits, or any number of things. The curtain might be constant or could be turned on when the mermaids hear boats coming. [Answer] A bubble curtain is a decent idea, but for something more static, that doesn't require continuous power... A sponge wall. You want a series of baffles that will allow water to pass through, but will choke and disorganize the flow, absorbing and dissipating shockwaves. Sponges will do that just as well in water as spongy materials do in air to absorb sound. If you want something that a person-sized creature can swim / crawl through to enter and exit and enclosure, you build the same kind of structure, just at a large scale, with person-sized twisty passages rather than food-particle-sized ones. Those could be larger passages carved through a thick wall of bioengineered sponge, or you could use other, stronger materials--e.g., a custom grown rocky coral reef. [Answer] Kraken Can't drop depth charges if your ships have been eaten. [![enter image description here](https://i.stack.imgur.com/ironT.png)](https://i.stack.imgur.com/ironT.png) [Answer] # By stopping the waves at the source These surface dwellers don't seem to know or care about this race. Of course, you can put up a shield, or breed sea monsters to deter approach, but that might actually make the land-folk more curious, and encourage them to come closer. When they find Atlantis the thing being defended, all the while being encouraged by continued losses, the will find Aliens! a hostile, hidden force. I predict very fast escalation, if not straight-away nuclear strike. Not an optimal outcome. This is, of course a simplified timeline, but unless peace is reached very fast, a war of extinction is quite probable. What would the average country with a sizable navy say, if they found that the Bermuda triangle is full of dinosaurs things who have secretly developed genetic hacking to such an extent that they can breed dogs into guns? They would quite probably assume that targeted diseases, i.e. biological warfare, is only a short design process away, or even stockpiled. Some trigger-happy general or president might decide to keep this tech out of any potential terrorists or enemy countries, by destroying it. I think that I've made it pretty clear that hiding is not a very viable option. Instead, I recommend one of two options: ## The best defense is an indiscriminate offense Since you can indeed breed things to such high usability, you could easily breed a [perfect](https://en.wikipedia.org/wiki/Alien_(creature_in_Alien_franchise)) [biological](https://en.wikipedia.org/wiki/Zombie) [weapon](https://en.wikipedia.org/wiki/The_Blob) (Just a few options). Or, you could go for a less overt option, and let them wipe themselves out. While hijacking a sub, and getting it to launch a nuclear missile would be quite difficult, there are other, similar options. If your ethics committee is OK with it, you could breed one of your own to be able to pass as human, and become a political leader who can start the war themselves. If nuclear fallout is not a desired side affect, and neither is extinction, or even a race of slaves, you can always try ## The best policy, honesty. If it wasn't apparen't already, I'm assuming that the surface-dwellers have no idea you exist. If they do, then they have basically been dropping bombs on you. They asked for what's coming. However, you could try giving a few examples of why they don't want to do that. This might make you a few enemies, but if you make the demo [impressive enough](https://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_area), they won't dare attack you. Or they might try their best to wipe you off the planet, but to be fair, they were already trying to do that anyway. If they don't then the remedy is simple: [Say hello.](https://en.wikipedia.org/wiki/The_Day_the_Earth_Stood_Still_(2008_film)) (This one has a more impressive "greeting" on the poster). How you go about doing this is up to you. You could breed a Kraken, and show up riding it into New York harbor. You could send Morse code through your specially bred whale orchestra. You could even go through Area 51. However you do it, eventually you will be able to go up to the UN, and demand that depth charges be banned. For a more impressive, if more risky approach, secretly sponsor a splinter group to start along the violent route. Then urgently contact a group of politicians, warning them of the threat, gaining yourself some friends, but also sending the message that these things need to be stopped. This also has the bonus of letting the community make space whales within the foreseeable future. [Answer] ## Yell at it The mer-folk could have their cetacean "sonic guns" create a countervailing shock wave. Since the energy of the depth charge is shared over the surface area of an expanding sphere, a very loud directed sonar blast by a dolphin / whale might disrupt it over a small section. Blue whales can produce 188dB and sperm whales can supposedly generate a 230dB pulse (<https://roaring.earth/sperm-whales-can-vibrate-humans-to-death/>). Add your many generations of breeding and you might be able to mitigate a depth charge pressure wave. The idea is a little similar to [explosive reactive armour](https://en.wikipedia.org/wiki/Reactive_armour). [Answer] If they don't breath air and perhaps travel along the sea floor, the mermen wouldn't have an air void. If there is no air void in the creature, the pressure wave wouldn't really do anything to the creature. Water is an incompressible fluid. Other than a 'supersonic wave' or cavitation, no damage would happen. ]
[Question] [ For a while now I've gestated this concept for a culture of people who live in a tropical rainforest populated with dinosaurs and other prehistoric reptiles. To protect themselves from the wildlife, they build treehouses analogous to those of the Korowai people of New Guinea (although other aspects of their culture have Central African influences). Near these treehouses they plant little gardens to provide them with fruits and vegetables, whereas the meat portion of their diet comes from hunting and fishing (if a treehouse happens to be built near rivers). Other features of their culture are iron-working technology, a system of government based on elder councils, and a religion with animal totemism and ancestor veneration (aka "ancestor worship"). What I want to ask about is possible gender roles for this culture. I'm a sucker for jungle huntress characters, so I don't want the stereotypical "men hunt, women gather/stay at home" scenario that most people associate with "primitive" cultures. Instead I have a setup where teams of young women do most of the hunting, whereas men and nursing/pregnant women stay behind to maintain the gardens and take care of domestic chores. Men would have the additional responsibility of using their strength to protect the clan's property from predators and enemy raiders. Families would tend to be matrilocal with men being the ones to move into a new family after marriage. Do you think this would be a viable design for a culture's gender roles? [Answer] You would need a reason why the raw strength of men is more useful in the villages than out on the hunt. I'd suggest that you can use the tree-living nature of your people to achieve that. Men stay in the village to haul heavy loads up and down trees, build new tree houses, and generally do the heavy lifting. In the meantime groups of women and younger (teenage) males go out in hunting parties along routes that would not take the weight of the men. They use nets dropped from above and spears, bows, or possibly even blow darts to hunt their prey. In this way agility and lightweight are values in hunters over strength, while raw strength is still needed in the village. (Particularly if they haven't developed the block and tackle so everything has to be done using raw strength and hauling on ropes with no leverage advantage). [Answer] While men are, generally, stronger than women, that is not likely to be your primary concern when talking about societal evolution. Murphy hit the nail on the head with his sentence that stated "many tribal cultures didn't have great population growth and males are thus a little more expendable since losing a few doesn't impact future generations as much". Especially in a treehouse society, mortality rates are going to be high\* and that is going to pressure the collective to place a higher value on the people that can give birth to new life. So question becomes: with the heightened preference to maintain female lives, why would men stay in the village near the children and elders (the most vulnerable groups, who would generally be in the least vulnerable position possible)? I think we can come up with a number of requirements and reasons. 1. Hunting is Not Particularly Dangerous I understand that you stated this world was populated with dinosaurs. Overall that is fine, but I would avoid the trope that the dinosaurs are all basically T-Rex's or raptors as depicted in Jurassic Park. If even a reasonable portion of them are, leaving the village to hunt is going to be exceptionally dangerous. If the females of breeding age were all out in a jungle full of raptors as their primary activity (effectively living the human side of the movie "Predator" every day), the society is going to die off fast. Stick with tiny dinosaurs that might cause injury but probably not death. Large, predatory dinosaurs jungles work better on TV than in reality anyway. As kingledion suggested in his comment, I would have the hunting parties mainly go after animals like monkeys and fish. 2. Inter-Tribal Warfare is Not Uncommon Resources are generally hard to come by in a jungle and everyone wants them. Men stay at home to protect the village and scout the area around it. Note that when a village wants to go to war it does send its men out because they are both stronger and more expendable. This is a very risky move however, as anything less than a sweeping victory may not leave enough males to defend their own village. Additionally, although women are not typically involved in aggressive action they are reasonable defenders, given that they hunt for much of the day. If you want to play on the dinosaur theme, perhaps the "bad natural enemy" dinosaurs generally stay out of the forest but will come in and attack groups of people. They might not see an advantage in chasing around 1 or 2 hunters who are just going to escape, but when they see a cluster of people they hear dinner bells. Men must fend off or destroy these large beasts until everyone else can get to safety. 3. You Live in Trees - Things Need Lifting and Building No reason to waste the extra muscle that hangs around the village. Goods and people that cannot climb well themselves frequently need to be moved between treehouse levels and the ground, and men supply the muscle that gets it done. They also perform jobs that involve construction while climbing trees, which is surely quite physically demanding. [Answer] Look at lion pride as your inspiration. Fewer males than females and the ladies do most of the hunting in a pride. Males hunt [solitary mostly](http://www.nbcnews.com/science/science-news/male-lions-do-help-hunting-after-all-f6C10149668), and the females hunt cooperatively. Their main function as part of a pride is protection of the pride. Societies can be set up however you would like, and in a jungle culture, there isn't much in the way of farming. Males might be encouraged to move silently, go out on their own and come back with berries and meat. Females could travel as a group to track large prey, with less focus on gathering. Age could actually be more of a determinator as to domestic things than gender, as you and others have suggested. A specific period of time could be devoted to pregnancy, and childcare during the first year for a woman, with the duties going mainly to the male thereafter. The actual miracle of birth could be something that the males feel they have to "pay back," as in the contribution of carrying a child and giving birth is seen as such a big deal, that the men must work to show they deserve it. During pregnancy, I can see the fathers going out to get rare herbs and other things, just in case something goes wrong, as part of the duty and ritual of it all. And I am going to drop some linkage on you regarding societies set up more like this: [The Aka](https://www.theguardian.com/society/2005/jun/15/childrensservices.familyandrelationships) [Matriarchies from around the world](http://metro.co.uk/2013/03/05/where-women-rule-the-world-matriarchal-communities-from-albania-to-china-3525234/) [Equal duties with the Agata in the Philippines](https://www.culturalsurvival.org/ourpublications/csq/article/agta-forager-women-philippines) [Answer] A terrible predator that can't climb drove them into trees in the first place. A giant alligator or salamander? The trees can't support a man's weight well enough for men to be mobile enough to be the best hunters. The lighter members of the tribe can leap from branch to branch. Men have to stay near the village to drive the big bads away. [Answer] A fatal genetic disorder that affects 99% of the men, and causes them to die between ages 18 and 25. The effect on the society is such that men are less educated (whats the point?), they have a strong incentive to enjoy life while they can (therefore less dependable), and their work is close to home because of the risk of them being affected by the effects of the disease. [Answer] # Change the genetics Currently there's statistically a 50/50 chance of having a boy or a girl child. If you increase the scarcity of males (say 15-20%) you're going to pretty drastically alter the culture and society. As Erin points out, a lion pride has a makeup that is mostly female with a male around to defend against other males (also when a male lion takes over a pride he will kill all the current offspring). [Answer] It is certainly possible man physical advantage or woman doesn't make that much of difference when it come to hunt since must hunters are ambush hunters who will not actually be fighting with there prey. The odds of a culture like this forming increase if there is a low population of men and constant chance of attacks from hostile tribes. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 7 years ago. [Improve this question](/posts/55576/edit) You are a fellow Worldbuilder and while travelling by train, you fall asleep. Next time you wake up you realize you woke up at [Grand Central train station](https://en.wikipedia.org/wiki/Grand_Central_Terminal). You quickly realize that you traveled not only through space, but also through time. The date is September 11 2000. Exactly one year prior to the World Trade Center attacks. You (obviously) can speak English well enough to communicate with people around you. You have all your clothes and everything what you carry in the pockets. Namely your cellphone. It always puzzles me whether one person can prevent the World Trade Center attacks. Would secret agencies believe that person? Also, you can tell to the agencies only stuff what you remember right now about the attacks [Answer] There are two ways to do this, the easy (selfless) way and the hard (selfish) way The Hard Way Call the local police station and tell them about crimes that you know happened in New York past said date of Sept 11 2000. If you predict them accurately enough, then when you say that Muslim Extremists are going to attack the World Trade Center, they in turn can set up Anti-Aircraft Artillery, (The much cooler Triple A) but this is difficult as it requires too much foreknowledge, all this does is save yourself if you are a selfish pig. The better choice is option B. The Easy Way When 9/11 occurred, it changed security on planes forever. Before the attacks, there were many things you could carry that are now out of the picture, ranging from toothpaste to can openers, to even Durex™ (I am legally bound to say Durex™ is not, nor has it ever been affiliated with TrEs-2b). Assuming that you are willing to go to any lengths to prevent this attack, the answer is as simple as it is ethically questionable; hijack an airplane. Buy an easily concealable weapon, such as a plastic butterfly knife or ceramic cane sword, the weapon matters not, the attack does. You need to instil fear into the Americans so that it becomes much more difficult to hijack planes. Name the last famous plane hijacking in America, post 9/11? Yeah. While it does suck, by hijacking a plane and committing a terrorist act, you can drastically decrease the odds of 9/11 happening. You can even go a step further and claim you are doing this for Allah, the one true god; making it even more difficult for the crisis to occur. Remember, the needs of the many.... [Answer] It may be difficult to prevent the attacks from happening. It is quite far-fetched a story to tell the pre-9/11 world. Also your seat-of-the pants knowledge can have gaps and inaccuracies, making an iron-cast plan difficult. However, what is really important here? Do you want to save the building, or do you want to save the people? The last is really easy. Find out how quickly the building can be evacuated. Then phone in a bomb scare ahead of time. You have a year to set this up, phoning in self-induced fires in abandoned buildings and seeding the police at large to ensure they will take it very seriously indeed by the time you need to be believed. And better have a file on you about 9/11 plans for the police to find in case you are caught out too early. Nice and cryptic with just enough hints. You may even spread out yourself to try and help all the 9/11 attack victims this way. [Answer] If you can make the agencies believe you don't depend at all on how you plan your attempts to stop it, it depends on how the time continuum works. The success of the timetraveller is already determined by how he knows the world and he can't ever change that timeline, unless he did not travel both in time and into a different universe. Why? Causality! # Setting the stage Let's assume our Timetraveller starts 2016 and manages to get a time machine for reasons directly or indirectly related to 9/11. He uses it to get to 2000 and somehow manages to prevent 9/11 the next year through some method, one or another. Now, how does the future unfurl? Here it comes into play how time is handled! ## Case A: Instable Time Loop This is also called the "[grandfather Paradoxon](https://en.wikipedia.org/wiki/Grandfather_paradox)" at times. Now, he has prevented 9/11. As he was directly motivated by 9/11 happening just how it happened, his younger self will never have reason to get a time machine and prevent 9/11. So he doesn't enter the time machine, which leads to him never going back in time to prevent 9/11. As he didn't go back to prevent 9/11, he is again motivated to go back in time to prevent 9/11. And we are back to the start of the loop. It is easy to see, that either, our protagonist has no chance of succeeding or getting out of the loop: If time travel removes the reason for the time travel, you can't get a stable situation as it flickers between the two alternatives! It is like a Schrödinger's Cat parable, where the box can't be opened ever again once it is closed.... However, there is a solution: ## Case B: Stable Time Loop The [Novikov self-consistency principle](https://en.wikipedia.org/wiki/Novikov_self-consistency_principle) tells that any time travel is only possible if the time travel has only results that have been part of the history already. You can't go back in time to change it, but there might be an alternative universe (many worlds theory!), where somebody from the future of 9/11 did go back in time and did prevent 9/11 in a way that would make sure, that somebody in the future did discover that the evidence that was needed to prevent 9/11 did come from his time and then went back to become this person. This Logical Loop that is created must be a self-fulfilling prophecy: in this AU 9/11 never happened, in no way. Just one person has to undergo the stable loop. However, this is not the only way, time travel can go on, there are other variants... (original text: [here](http://thelifeofpsi.com/wp-content/uploads/2015/01/Lossev-Novikov-1992.pdf)) ## Case C: Doctor Who Now, Dr. Who is clearly not a non-stable or a stable time loop all the times, but somehow manages to have a roughly linear personal timestream (that the timeline of the world around him is an entangled yarn ball doesn't matter, he has personal timeline superiority!). He does adhere to some of the Novikov rules but breaks them at other points. Still, for him the [Blinovitch Limitation Effect](https://en.wikipedia.org/wiki/Blinovitch_Limitation_Effect) is governing (most of the time): * You can't redo or fix anything you did yourself * You can't have any contact with any of your earlier selves or face some heavy energy discharge On itself, this would not prevent the time traveler from going back, but he can't go back to fix his own mistakes. So he can't just "try again", and if he doesn't manage to prevent 9/11, he can't try again. He could, however (under the paradigm), try to prevent some other thing, as long as it wouldn't void any of his prior time travels. # Conclusion: Causality needs to be maintained! No matter how time travel is achieved or what method is taken to ensure the success, one has to adhere to the principles of 4D Logic, that is one has to advert time paradoxes at any cost. Maintaining the Causal Loops is essential! In a world without 9/11, there wouldn't have been a War on Terror. Iraq wouldn't have been invaded. Possibly the Arabian Spring wouldn't have risen. Maybe there wouldn't have been the ISIS either. Now, any reason that springs from these can't be a reason for the time travel or the result is a non-stable time loop, casual instability and time paradox. Our time travel reason needs to be something that ensures the time travel is being taken to fulfil Case B. If we add Case C, it is just a complication, that makes sure that the time traveler has to try his best to succeed - if he would not, nobody would be able to fix his mess, as those others wouldn't remember it any differently (and neither he), and at the same time he has still to ensure he did the time travel in the first place. # Way out Now, If he remains in the same universe, the one he came from, then he can't change the path it will run down until the time he started his time travel - either because he would create a non-stable time loop and would end in the Schroedinger state of probable success and failure at the same time, or because he adheres to Novikov and ends up being ignored. However, there is a way out that I mentioned earlier: Many worlds Theory. Instead of just going back in time, our "time traveller" ends in a branching universe that differs in at least one point from the one he came from, he is there. It might have more differences (Schwarzenegger was President?!), it might be otherwise identical - but this opens up the whole area: It is no longer creating causality errors to prevent or fail at preventing, as you don't try to change the system with the results of it. Instead, you know how system A played out and then alter the conditions in system B, that is the same in most but not all details. [Answer] # Kick the hornet's nest At around 0600 to 0700 Eastern Time, September 11, 2001, you call 911, you call news agencies, you call TV stations. You tell them that there are bombs placed on American Airlines's flights 11 and 77, and United Airlines flights 175 and 93. And that there are vans loaded with explosives will drive into World Trade Center Towers, the Pentagon, the White House and the Capitol. You have spent the year reading the manifestos of Osama bin Laden and knows his arguments. So you add suitable passages from these in the calls. Then you sit around and wait for the police to show up. Accompanying you are former Washington Post reporters Bob Woodward and Carl Bernstein. This is because you have previously called them and said "[William Mark Feldt Sr](https://en.wikipedia.org/wiki/Mark_Felt) is Deep Throat". And you have shown them your phone. At around 2001, cameras on phones was next to unheard of. Digital cameras were at about 1 Megapxel at the very most. My Samsung Galaxy S6 can do great pictures in near darkness, at 16 Megapixels. The biggest problem you will have with it is trying to charge it since micro-USB is still a few years away. There will be some huge confusion but unless people are phenomenal idiots they will be rattled and intrigued enough to look closer at the passenger manifests of those flights, even more so if you say "19 guys will board with box cutters and other such tools". What happens there-after is anyone's guess... but you have at least cleared out the WTC, the White House and Capitol. You will have made people look closely at who was scheduled to fly of those flights. This may perhaps prevent the attack. But whether this actually catches the baddies or if they escape and try again is anyone's best guess. [Answer] Recruit your younger self. Take: a) Your smartphone from the future b) Your younger self, genetically identical yet sixteen years younger. Then head into a major news outlet, the New York Times would do, and tell the whole truth, in as much detail as you can. Then make yourself available for clarifications and testing. Even if you're not believed, you will make enough of a splash to derail the WTC attack plans. Don't forget to warn about Fukushima while you're at it! [Answer] Bear in mind that actual FBI agents who saw what was coming were unable to prevent the attack. Now granted, you have specific information such as date and who and where, but you're also much more likely to be regarded as a crank call. I think your best approach would be to call the security office at Logan airport from a payphone and tell them that you know that Arab terrorists are going to try to hijack multiple planes that morning using box cutters as weapons. Hopefully they'll take extra screening precautions that day. They may figure you're a crank call, but it still might make them paranoid enough. I think your cell phone is basically useless. You won't be able to find a charger for it, it won't connect to any networks. You might be able to connect to WiFi, but what would you connect to that could be any help? You might be able to show it to people to prove you're from the future, but do it quickly before the battery dies. And be prepared to be thrown into a cell while they study you to find out how you travelled through time. --- Also: as an aside, when the FBI tracks the call to that payphone, and checks the coins for fingerprints, imagine their surprise when they find a dime with a date in the future. --- One more comment: a lot of other comments and answers sort of assumed that you had a chance to plan your trip in advance, e.g. by memorizing key facts or putting data into your cell phone. But the original scenario was that you, unprepared for what was about to happen, find yourself in the past. I certainly haven't memorized the flight numbers or even the airlines involved. I might be able to remember a hijacker's name or two. Could I name any major events between 2000 and 2001 to convince people I was from the future? That might be a little easier. IIRC, that was the year that Bush won by 500 votes in Florida. Tell people that "hanging chads" was going to become a popular term, and Dan Rather's "pregnant with possibility" quote would be misquoted as "pregnant chads". Mention "butterfly ballot" and you're in. Also mention Arabs taking flight lessons in Arizona. If the FBI follows up on it, then the agent there who tried to warn of the attacks might be taken more seriously. --- References: In the book [Replay](https://en.wikipedia.org/wiki/Replay_(Grimwood_novel)), the protagonist finds himself sent back to 1963. One of the first things he tries is to stop the Kennedy assassination. In the web series [Red vs Blue](http://roosterteeth.com/show/red-vs-blue) a main character repeatedly goes back in time to stop previous disasters from happening, only to wind up being the cause of each of those disasters. In [Outlander](https://en.wikipedia.org/wiki/Outlander_(TV_series)), the main character tries to stop the massacre at Culloden, but everything happens exactly according to history no matter what she does. [Answer] # Buy an Aviation Band Radio Park under the departure path of the airplane. Tune to the relevant Tower or ATC frequency the plane will be using when overhead. Call the pilot and tell them that there are hijackers onboard with box knives. Explain that they mean to use the plane as a weapon, and not just as a negotiation tactic. That's really all anyone needed to know. You wouldn't save the planes, necessarily, but they wouldn't hit the WTC or the Pentagon. That information was enough to stop the 4th plane on 9/11 already. [Answer] As long as your goal is only to prevent this particular attack, this is not as hard as it sounds. You do not need to prove or even reveal that you are a time traveler or have knowledge of future events. There was already one attempt made in 1993 to take down the World Trade Center. A plot to destroy the Holland and Lincoln tunnels and attack other New York City landmarks was foiled the same year. Any plausible information about specific new attacks is sure to be investigated. So, the simplest thing to do is a month or two before the attacks send the FBI a letter which says something like this: > > Over a dozen men from the Middle East are studying at US flight schools (maybe in Florida). They are learning to fly jumbo jets. They do not care about learning to land because they want to fly them into buildings. They hope to hijack several planes on the same day. They think the crews will cooperate if they threaten the passengers with small knives and do not tell them what they intend to do. They will probably hijack long-distance flights leaving the East Coast so that there will be plenty of fuel to cause the most damage. The World Trade center is definitely a target, but there may be others. They hope to do this on September 11th so that the date will be 9/11 (911). > > > I have included only information which I am pretty sure the conspirators knew before the attack. The FBI will assume that this information comes from inside the conspiracy, perhaps because one of the conspirators blabbed. The information which I have included describes a novel but plausible attack. It does not matter whether the FBI thinks it would work, they will follow it up because it is a hijacking. The FBI in Arizona already wonders why students from the Middle East are studying at US flight schools. Once they find out that some of them have taken tickets for September 11th, they will give them their full attention. [Answer] Yes, a single person can prevent the 9/11 attacks. One year prior is plenty of time to change outcomes significantly. Sensitive Dependence on Initial Conditions The event of 9/11 was the culmination of every single preceding event. Change one tiny little thing and you have most probably (in fact, in all probability), drastically changed the odds on 9/11 occurring. Personally, I maintain that if I wasn't so slow to learn to tie my shoelaces as a child, then 9/11 wouldn't have happened. But it would be irrational to blame myself (or Velcro, for that matter). [Answer] Technology has improved so drastically and continues to do so at a faster rate all the time. One person by itself would find it very difficult to prevent the attacks...so I would find allies...with your cellphone you can show technology understandable but not possible to produce 16 years ago...find technologists in the private sector that would understand this, it will be proof of your assertion of future origin, once they believe that, they will believe the rest, then involve the government (FBI). By the way, guard your six...you do not know who might bring you harm...after all the enemy is committed and with ample financial resources. [Answer] It should be pretty easy to prevent the attacks as you have one critical piece of evidence in this scenario. Head to the Pentagon. Explain that you are a time traveler and that you are attempting to bring warning of the 9/11 attacks. Think I'm a kook? Explain where I got this (smartphone). Nothing of the sort existed in 2000, they'll have to take you seriously. [Answer] If you prepare a detailed "schedule" of major events that happened that year and send copies to many news agencies and law enforcement agencies, most will throw it away and not be able to evaluate it. But maybe some will keep it and realize along the way that it has been "accurate so far." A problem however: the less information on it, the less convincing it will be, but the more events listed, the more likely someone will take action on them, thereby changing what will happen, making your list less accurate! [Answer] One year before the attacks, you have the opportunity to attack the attackers, or at least prevent them from being able to set the project up. They learned how to fly in the USA. Through some concerted effort, you should be able to track them down and take some pre-emptive action. There might well have been some back-up plan, but if you take out enough of the key players or do something to interfere with their plans, then the attacks would be prevented. You don't have to take them all out, just one or two of the key players and the whole plan falls apart. If you woke up on that day without knowing who the attackers were or where they were training, then you'd do what you could to affect how airline pilots were trained. [Answer] Yes. Just breathe. Or even don't; just be there. One year is a huge amount of time relative to the scales at which the dynamical systems behind the world are chaotic. A single change now in a single air molecule will yield a one-year-out future that looks nothing like "before" the change. ]
[Question] [ It’s rather cliché that an alien message would use a value like π (actually I expect it to be 2π because Earthlings are weird), but in my story the message which contains the bootstrap information for reading the message has natural numbers as an atomic construct, and fractions, continued fractions, and other ways of expressing a non-whole positive value (let alone a transcendental value!) are built up out of more primitive elements.※ The lesson on the basic feature of natural numbers can illustrate counting, high enough to show every digit and how positional notation works.‡ But then it should give some large numbers, so the decoder/receiver can know he’s reading it properly. Now if you were to receive the value of e you’d recognize it as being something special, and out of all the possible numbers you’d know this was “right” because it is distinct and recognizable. But, what numbers in ℕ are like that? What positive whole number, that’s not too short but needs a bunch of digits, will make the recipient recognize it as being a special somewhat unique value? If a single value can’t do it, then perhaps a sequence. Primes are too dull and don’t grow fast enough. Something like a list of consecutive powers is too arbitrary. --- Edit: To clarify, this number is not sent/presented in isolation with any need to show artificiality by itself. It appears in a huge message that’s already bootstrapped the main message low-level encoding as “pages” containing images and language encoded as binary files. This number is to be a “cool” example to conclude the page explaining how natural numbers are encoded in the binary language file. By “binary language” I mean similarly to how we would store a 32-bit number as 4 bytes (essentially base 256) and how you know to expect a number and how long it is. Not exactly. It’s like digits in some ways… but think of a text file where digits are bytes 0x30 – 0x39, not pictures of what our glyphs look like. --- ※ identifiers (“words” and “symbols”) other than numbers, and sentences such as needed to express relationships and algorithms are also build on top of this. Simple expressions like `2+3=5` start on the next page. ‡ details: (spoiler if you’d like to figure it out later when I post the completed image on [puzzling](http://puzzling.stackexchange.com), don’t look at the hidden parts.) The message is composed of 6-bit elements (hexets) and the way the channel coding was explained in the simpler/slower/cruder earlier part, it’s clear which code is `000000`, `111111` etc. Well, maybe 4-way ambiguity as to the significance of the order and whether the solid mark is a 1 and hollow is 0 or vice-versa. > > Anyway, one natural way of assigning numeric values to hexets will show o00 through o56 assigned to “digits” with the same value. A natural number is introduced with hexet o57 and followed by digits in little endian. > > > The page is ruled into boxes, with many small boxes on one row at the top, getting larger and larger until boxes fill a whole row and then continue to get taller. Each box has spots in it. They are a few pixels across but vary in size and shape, being irregular in shape. They even have different “colors” (pixel value; reader chose palette arbitrarily). The spots are irregularly positioned as well, clumping here, rarified there. The first cell has no spots; the next 1, then 2, etc. all the way up to 53 or so, > > so it gets into numbers that need 2 hexets to represent. Also in each cell is the label, which is also positioned irregularly in each cell but never touching the rule lines. The labels show o57 o00 in the cell with no spots, o57 o01 in the cell with 1 spot, up through o57 o56 in the cell with 46 spots, then o57 o00 o01 in the cell with 47 spots, through o57 o05 o01 for 52. > > > > You see directly each digit, then that it is positional and in what order. > > > But it does not carry on counting any higher; large enough to show anything useful would be impractical. So I think it will go to some sequences after that. The big cool numbers come at the bottom of the page. [Answer] I'm interpreting this question as "Is there a large(ish) natural number, the knowledge of which is evidence of advanced maths, and which is in some sense universal" The theory of groups is of fundamental importance. It arises naturally from the analysis of symmetry, a basic property of nature. Among the groups, some have no normal subgroups, and such a group is said to be simple. Some simple groups are in families, and some are said to be "sporadic". It is an important fact that there are only a finite number of such sporadic groups, and so there is a largest such group. Given that groups arise naturally, and the size of the largest such group can be calcuated. It provides (in the words of the question) a "positive whole number, that’s not too short" and a mathematically literate species can "recognize it as being a special somewhat unique value". I claim that any sufficiently advanced species would know this value (of course I can't prove that, but the same can be said of any other value: pi, e, or the prime numbers). The largest such group is called the [monster group](https://en.wikipedia.org/wiki/Monster_group). It has 808,017,424,794,512,875,886,459,904,961,710,757,005,754,368,000,000,000 elements. This sequence of digits, while perhaps not obvious to a non-expert, would be easily recognisable as something special. It shares the properties of pi and e: * Uniqueness * Universality * Distinctiveness * Importance Moreover, every digit from 0-9 appears at least once. There is a sequence of simple sporadic groups, but this attempts to answer the OP question without invoking a sequence, instead with a single large significant number. So the scene goes: Scientist A: We thought we had worked out the digits, but then we got this long random sequence. In our notation it is the number 808, ... 000. Scientist B: I wonder if it means something? [[googles]](https://www.google.co.uk/search?q=808%2C017%2C424%2C794%2C512%2C875%2C886%2C459%2C904%2C961%2C710%2C757%2C005%2C754%2C368%2C000%2C000%2C000&oq=808%2C017%2C424%2C794%2C512%2C875%2C886%2C459%2C904%2C961%2C710%2C757%2C005%2C754%2C368%2C000%2C000%2C000&aqs=chrome..69i57&sourceid=chrome&ie=UTF-8) It's the order of the monster group. We are right! We do understand their number system, and we know that they are capable of advanced maths. (Google only needed if a David Laughlin character is not available) [Answer] A sequence of Pythagorean triples should do it. * 3, 4, 5 * 5, 12, 13 * 8, 15, 17 * 9801, 1980, 9999 * 1001, 501000, 501001 The beginning of the sequence is very recognizable in pattern and works with single digits. The second two are the next two Pythagorean triples, basics of geometry. Then you get into larger ones. The math ($a^2 + b^2 = c^2$) is easy to check and lets you know that you've got the positional notation right. Even better, you can pick arbitrarily large triangles to scale up if there's something special in your notational system at, say, the 1 million mark, or whatever. [Answer] I suspect you may be overthinking this. Why not just transmit a simple [geometric progression](https://en.wikipedia.org/wiki/Geometric_progression) like, say: > > 1, 3, 9, 27, 81, 243, 729, 2187, 6561, 19683, 59049, 177147, 531441, 1594323, 4782969, 14348907, 43046721, 129140163, 387420489, 1162261467, ... > > > The first few numbers are small enough that the pattern should be easy to spot, but they increase rapidly. There's a simple one-to-one relation between successive pairs of numbers — the next one is 3 times the previous one — and the numbers in this sequence are also recognizable on their own, being the only numbers not divisible by any prime other than 3. The base of the progression can indeed be chosen more or less arbitrarily, but I would suggest that it should preferably be: 1. reasonably small, so that the sequence doesn't grow too fast, 2. a prime, so that each number in the sequence has a simple prime factorization, and 3. not equal to (or sharing a common factor with) the base of your number system, to properly exercise the receiver's decoding system. Thus, for base 2 (or base 2n) or base 10 numbers, 3 would be a good choice of base for the progression. If you're using e.g. a base 3 number system, the powers of 2 would make a good test sequence. If you're using, say, base 60 like the ancient Babylonians did, try the powers of 7. [Answer] First off, I recommend [OEIS](http://oeis.org/), the Online Encyclopedia of Integer Seqences. We could post answers all day long here, but OEIS has them catalogued. Primes may be boring, but don't discount them. They are a very unique feature of the natural numbers. If I was going for clarity, boringness is a virtue. You want it to be boring. Boring and un-misinterpretable. Sequences are definitely the key. A number without context is meaningless. Sequences naturally give context to every number. If all you wanted were "big numbers," you could have fun with the [Ackermann function](https://en.wikipedia.org/wiki/Ackermann_function). Those get big quick, but they're awfully specialized. Another option might be to have parallel sequences which each give each other context. Consider ``` x 1 2 3 4 5 ... x+x 2 4 6 8 10 xx 1 4 9 16 25 x^x 1 4 27 256 3215 ``` These series grow fast. In addition, you can just keep the pattern going, going through the hyperoperations. You can do [tetration](https://en.wikipedia.org/wiki/Tetration) (`1 4 7625597484987`... oh my that jumped quickly!), [pentation](https://en.wikipedia.org/wiki/Pentation) (A series which grows so fast our positional notation might as well be a primitive counting system which counts "1, 2, many") or any similarly exotic function. Another twist on primes might be offering prime factorizations of large composite numbers. Given that we rely on that factorization being difficult for RSA encryption, such sets would certainly catch people's interests. [Answer] What about the [Fibonacci series](https://en.wikipedia.org/wiki/Fibonacci_number)? > > 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765... > > > They come up frequently in nature (at least on Earth), are very easy to calculate and recognize, and grow relatively quickly. > > $F\_n = F\_{n-1} + F\_{n-2}$ > > > [Answer] So, you want a number sequence that someone who has no idea what your numeral system is is able to recognize and extract your numeral system from it? I take it you're using a fixed-base positional system like a normal Type I+ civilization would? Let me suggest ... the factorials.* * Primes grow too slowly for you? Fear not. The factorials will leave the primes, and even the most ambitious of power sequences, in the dust. [Few sequences](https://en.wikipedia.org/wiki/Fast-growing_hierarchy) grow faster than the factorials, and you want a sequence whose values can be written down anyways, don't you? * Not too arbitrary. $a\_n = \prod\_{i=1}^n i$ has no parameters to tweak, except perhaps the $i=1$, and tweaking that doesn't achieve anything good. This increases the chance your recipient makes the right guess and decodes your sequence successfully. * The factorials have a recognizable pattern in their numeric representation, no matter what numeric base you choose - those long chains of zeroes spanning the half of each number, with new zeroes popping up at regular intervals. Not only does it allow your recipient to recognize the zero, it also allows them to recognize the comma, and even narrow down your base. Very important. Once they know the sequence and the comma, the rest is a breeze. * There is enough entropy that every digit you have crops up soon enough and can be recognized. You don't want people to be guessing whether 삼 is 3 and 팔 is 8, or vice versa, when they finally crop up in the message itself. The factorials grow so fast you only need about as many numbers as there are symbols in your base. While similar is the case for most sequences and chaos is on your side, some sequences fail spectacularly. 1, 2, 4, 10, 20, 40, 100...? No good. You might still want to add the sequence of your digits in order to your message. It isn't strictly necessary, but it shows the other side that you're a nice guy - and, if you happen to be using a numeral system with negative-value digits (I'm looking at you, Setunians), this sequence will surely help clear that out. [Answer] I was surprised that no one mentioned [Catalan Numbers](https://en.wikipedia.org/wiki/Catalan_number) for a possible sequence. I would speculate that the inference of a binary numbering/counting system expressed in a combinatorial sequence suggests an understanding of logic systems and binary computation, but does not assume more advanced knowledge. Though perhaps my view is biased. Admittedly I do not know the history of group theory, though I have seen mention of it briefly when reading about E8 Theory. ## Edit ### Useful Interpretations of Catalan Numbers Catalan numbers are presented in [OEIS](http://oeis.org/) series [A000108](https://oeis.org/A000108). The first few numbers in the series are 1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845, ... Referring to the number Cn as the nth Catalan number, where { C0, C1, C2, ... } = { 1, 1, 2, ... } here are some interpretations ( quotes are from the wikipedia article ): > > * Cn counts the number of expressions containing n pairs of > parentheses which are correctly matched: > > > ((())) ()(()) ()()() (())() (()()) > > > * Successive applications of a binary operator can be represented in > terms of a full binary tree. (A rooted binary tree is full if every > vertex has either two children or no children.) It follows that Cn > is the number of full binary trees with n + 1 leaves: > > > [![Binary trees with n=3+1 leaves](https://upload.wikimedia.org/wikipedia/commons/0/01/Catalan_number_binary_tree_example.png)](https://upload.wikimedia.org/wikipedia/commons/0/01/Catalan_number_binary_tree_example.png) > > > * Cn is the number of different ways a convex polygon with n + 2 > sides can be cut into triangles by connecting vertices with straight > lines (a form of Polygon triangulation). The following hexagons > illustrate the case n = 4: > > > [![Triangulation of polygons with n+2 sides leaves](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Catalan-Hexagons-example.svg/400px-Catalan-Hexagons-example.svg.png)](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Catalan-Hexagons-example.svg/400px-Catalan-Hexagons-example.svg.png) > > > * Interestingly, Spenser Mortensen has [described](http://spencermortensen.com/articles/serialize-a-binary-tree-in-minimal-space/) a means of uniquely identifying ( serializing ) any binary tree using Catalan numbers in a sort of hashing function - providing a single numeric value which can uniquely represent the entire structure of a given binary tree. ### Rationale for Reducing the Sophistication of the Chosen Symbolic Sequence 1. The maxim, often attributed to Einstein, but to paraphrase, "Everything should be as simple as possible, but no simpler", I think applies here. I would put it this way, let's say it is safe to assume that the recipient of such a message would need some form of computation in order to receive and decode the message, call it a minimum requirement. However, as one sending such a message, I would not assume that the recipient has any more than the necessary knowledge to both receive and decode such a message. If the message itself is the base-line, rather the need to send a message and have it be received is the minimum requirement, then why place any higher requirement on the recipient? 2. Given the nature of the described content that will be transmitted, it seems that a fair portion of it may be amenable to encoding based on the nature of the Catalan Numbers themselves. Certainly anything to do with binary trees or binary operators ( such as representations of recursions of addition, subtraction, multiplication and division ) would be. An perhaps other geometric proofs as well. [Answer] The most recognized natural number based off my memories of grade 3 is 58008. Now, this seems silly, but a serious problem is that we are presuming that the people we are communicating with have similar values and knowledge. It is really, really hard to find a natural natural number; natural numbers in this universe are actually approximations of seemingly continuous phenomena. As far as we can tell, even the count of protons or neutrons in an atom are just (very accurate) approximation of what "is" is there. If we limit how alien the aliens are -- they are biological-like organisms built out of chemistry-based life -- then we have a place to start. Assuming that exponential functions are special to them like they are in our mathematics may not be justified. As a really trivial example, the triangle numbers could be viewed as "as natural" as the square numbers, and have been by previous cultures. The resulting physics may be awkward, but they might be using a different way to model physics than we are. (There are many ways to model human physics; an unknown alien might prefer different ones, or even discover different ones). --- Personally I wouldn't send a large natural number until after I communicated algorithms. Then I'd describe an algorithm that generates a large natural number, and communicate that. Equations are good, because you can describe how to get the number using math, then repeat the number using a different notation, and do this a few times. Possibly getting the notion of "equals" is key. Try to communicate using as many strange ways as you can come up with. Issue "rosetta stones" of messages -- many messages that "all mean the same thing". Draw images using various simple formats. Build the foundations of mathematics more than one way. Try to describe things both the reader and writer might have in common, like the emission lines of hydrogen. [Answer] Slightly less boring than the primes, faster growing than the factorials, and less obscure than monster groups, are the [primorials](https://en.wikipedia.org/wiki/Primorial): Products of the first $n$ primes. $$p\_n\# \equiv \prod\_{k=1}^{\infty} p\_k$$ Where $p\_n$ is the $n$th prime. The first few primorials, from [OEIS](https://oeis.org/A002110/list): $$ \matrix{ n & p\_n\# \\ 0 &\hfill 1 \\ 1 &\hfill 2 \\ 2 &\hfill 6 \\ 3 &\hfill 30 \\ 4 &\hfill 210 \\ 5 &\hfill 2310 \\ 6 &\hfill 30030 \\ 7 &\hfill 510510 \\ 8 &\hfill 9699690 \\ 9 &\hfill 223092870 \\ 10 &\hfill 6469693230 \\ 11 &\hfill 200560490130 \\ 12 &\hfill 7420738134810 \\ 13 &\hfill 304250263527210 \\ 14 &\hfill 13082761331670030 \\ 15 &\hfill 614889782588491410 \\ 16 &\hfill 32589158477190044730 \\ 17 &\hfill 1922760350154212639070 \\ } $$ Note that some of the properties of factorials are missing - the trailing zeros, for example, - but I'm assuming you've got record separators established in an earlier part of the transmission. One disadvantage is that there isn't any obvious individual number to choose. If it's necessary to use a sequence, this might be a good choice. If the senders don't trust that the receivers have tools like google and OEIS, they could even send a table like this: $$ \matrix{ n & p\_n & \sum p\_n & p\_n\# \\ 0 &\hfill &\hfill 0 &\hfill 1 \\ 1 &\hfill 2 &\hfill 2 &\hfill 2 \\ 2 &\hfill 3 &\hfill 5 &\hfill 6 \\ 3 &\hfill 5 &\hfill 10 &\hfill 30 \\ 4 &\hfill 7 &\hfill 17 &\hfill 210 \\ 5 &\hfill 11 &\hfill 28 &\hfill 2310 \\ } $$ Where the $\sum p\_n$ values are the [sums of the first n primes](http://oeis.org/A007504/list). (I discovered primorials because they are the cycle lengths of the gaps between [rough numbers](https://en.wikipedia.org/wiki/Rough_number).) [Answer] To show we are able of complex maths, we first of all show that we are able to create a simple message that can be easily understood. The message I used in [this question](https://puzzling.stackexchange.com/questions/42201/how-many-fingers-do-the-aliens-have) seems the perfect candidate. Basically we create a sequence of symbols from which aliens can deduce a sequence of numbers and symbols used for arithmetic operations on those numbers. This message is just not only a numeric sequence, but it actually shows the alien * We know what "encoding means" * We know how to make a encoding meaningfull (they don't have a dictionary to lookup each symbol, so where "symbols starts and ends" it should be obvious) * We know prime numbers and basic algebra After that, we agreed on a simple alphabet (or maybe show that we don't want be bound to an alphabet, we could change it everytime, making them aware that we know that alphabet is not important, as long as you can deduce what symbols are used for), we could use it for buildling more complex subjects. If we just send a plain numeric sequence we are just screaming: ``` "Hey radio amateur here! Testing, 1, 2, 3" ``` Instead if we provide something simple but that allows us to build a language, we are clearly showing the intention that we want to communicate and send complex messages. Also, if the message is simple enough, anyone determined enough could figure its meaning, and even better he could actually learn from it! > > Assume actually there's a Remote terminal built by an ancient alien race, then those aliens are died, and there's a new race that actually have no technologic/math knowledge. > > > However if they see on the terminal something like(our signal sent from far far away): ``` O 1 OO 2 OOO 3 OOOO 4 O+O 1+1 2 OO+O 2+1 2 ``` They could as well start to learning doing sums and counting, and all based solely on observation. The interesting fact is that we are not able to send images, speak of how is the weather or what your name is, but we are able to encode math. Axioms, Theorems, Proofs. No matter what their language is, you can (with a really well-though message, starting really simple) encode almost all the math and actually teach it. Now that I explained the rational, here's the lesson for the aliens. I used our characters to keep that understandable to us, but in reality any symbol could be replaced with another sylmbe without losing the meaningfullness of what I write. Here is how do we really encodes algebra to arbitrary symbols: ``` ____#__1_2_3_4_5_6_7_8_9__0___#_1___##_2___###_3___####_4___#####_5___######_6___#######_7___########_8___#########_9___##########_10___###########_11_##################_18____ ``` The message with "\_\_\_" replaced by newlines ``` #__1_2_3_4_5_6_7_8_9__0 #_1 ... ##########_10 ##################_18 ``` This basically teach to count. There's enough to understand positional notation and to understand what "#" and "0" means. For the next Lesson we could start doing sums ``` #__1_2_3_4_5_6_7_8_9__0__+__= #+#=## ##+#=### ###+###=###### 1+1=2 2+1=3 3+3=6 #####+######=########### 5+6=11 9+1=10 99+1=100 23+37=60 5+17=22 ``` Yes, it is very concise with few, but sufficient examples to learn sum. We could also sent a sum table as "extra" of course in our message. Teaching division/multiplication is the same, I just want to skip that boring part and become functional: ``` #__1_2_3_4_5_6_7_8_9__0__+__=__x__f__(_)_@ @f(x)=x+1 f(1)=2 f(2)=3 f(4)=5 @f(x)=x+4 f(0)=4 f(1)=5 f(7)=11 ``` Now that we have functions we could define our first axioms ``` @0 @f(x)=x+1 @0_f(x) @f(0)=1_1 ``` And after we have our Axioms (almost all Peano Axioms, but induction principle), we have almost defined our natural numbers. Well, in reality it is incomplete, we need first to define "Sets". But without too much effort in being too precise, we did already a lot of setps forward. --- Assuming the aliens use that encoding for their messages, then to be sure someone is reading the message properly I would not use a single number but a expression to check equality, something like: ``` 101*103=10403 ``` Alternatively I would use the page number ``` 1 for page 1 ``` Or a number that represents some function like the number of boxes in the page raised to itself, if there are 10 boxes then then number is `10^10` ``` 10000000000 ``` Personally I would choose the last option, because it is not only a number meaningfull in the "page context", but it actually provide usefull as a simple "checksum", once someone reading figure what that number is. --- [Answer] As Cort Ammon, I'd like to suggest [OEIS](http://oeis.org/) as the catalog of many important integer sequences the humanity found so far. More specifically, a good starting place is the [core sequences](http://oeis.org/wiki/Index_to_OEIS:_Section_Cor#core) list. From there, I'd pick some sequences which are not based on arbitrary integers (for example, the power series of x is obviously based on x). My list would be something like: 1. Natural numbers or prime numbers. However, you specify you want the numbers to grow faster than that, and maybe a sequence this simple is already covered with the prior setup in the message. 2. [Factorials](http://oeis.org/A000142) or the [Fibonacci](http://oeis.org/A000045) sequence. Basic enough to make sense of them even for a person not mathematically inclined. 3. [Catalan](http://oeis.org/A000108) numbers. They appear naturally in [quite a number](https://en.wikipedia.org/wiki/Catalan_number#Applications_in_combinatorics) of ways. 4. Something more abstract, like the number of certain [groups](http://oeis.org/A034383) or [graphs](http://oeis.org/A000088), if you want to show what algebraic structures are familiar to the humanity. ]
[Question] [ I'm trying to create well-off country, which judging solely by GDP per capita would be considered wealthy with something like 60,000 USD per capita. However the country middle class is very small. Is such economy possible? If that helps my story is about failure of the country to democratize, since rich are afraid that populist will take all their wealth. The working class on the other hand could always find job, but has largely given up on trying to improve, unless you are very talented or very lucky. The story happens in present age. So far I'm pondering below things: * Low taxes and little redistribution of income * Suppression of unions * Modern sector made of Capital intensive industry which that pays high wages but employs few and high skill services which only hire brightest and best educated * Unproductive traditional sector which soaks surplus labor (South Korea [but many times worse](https://www.bbc.com/news/business-14554015) * Expensive private vs low quality public/religious education * Part of the population works very little due to religious reasons (inspired by Haredim in Israel) and lives off government handouts * Very few public jobs (small administration, professional army etc) * mechanized agriculture [Answer] ## Gated Nation One scenario that comes to mind is Monaco. One in three is a [multi-] millionaire. Most of the working-class do not live in Monaco, but commute from France. The "country" is full of rich people (is that a "rich country"?), but has a small if not non-existent middle class citizenry. ## "From Each According to His Ability, To Whatever." Another scenario that comes to mind is pure State ownership. I know this has not really panned out in real life, but in theory, the "country" can be "rich" if all wealth is owned and distributed by the state. Distribution can be absolutely even, thus rendering everyone in the same class, or it can be uneven such that some get most and the rest get sh\t. ## Feudalism / Oil Oligarchies Another scenario is common in the middle east. Vast wealth is owned by a small ruling class or even a single ruling family. This family has mechanisms to generate vast wealth, and it's up to them to allow or forbid anyone else in their turf to do or own whatever they deem fit. Of course, prior to the post-war rise of the middle-class, there was no middle-class. So, if we take feudalism as an example, if any king could generate wealth then you would say that that king's country is "rich." Was ancient Egypt "rich" or was it mostly a country of slaves forced to collect gold and bury it with a select few powerful individuals? ## You, Robot I think a lot of this would be easier if there was a large robotic or mechanized work-force. The middle-class are indeed useful for advancing and stabilizing a free society. One option, then, is to not have a free society. You could obtain your skilled labor from robots, thus keeping a lower class relatively unskilled and thus uneducated and unempowered. The resources generated by these robots could then be used to appease (free sandwiches) or control (police) the lower classes. These robots could be designed/owned/manufactured by the ruling class, or, the ruling class could have just purchased them from another country. [Answer] What does it mean to be wealthy?* If you'll forgive a [Frame Challenge](https://worldbuilding.meta.stackexchange.com/questions/7097), you're trying to define wealth in terms of money and then you want to level out the playing field. That doesn't work. Wealth must be defined in terms of luxury, influence, and power. In other words, a wealthy person is one who can secure the services of others in circumstances when the majority cannot do the same. After all, what does it mean if everyone in a nation "owns" the same mount of land or "earns" the same amount of money? Answer: nothing. To quote from Pixar's The Incredibles, "Everyone's special, Dash. ... Which is another way of saying no one is." Producers, Consumers, Givers, and Takers A viable society requires everyone to be some percentage of producer, consumer, giver, and taker. This is where a great many people don't get it. Now, because this isn't the place to write whole books, I'm going to really simplify this.1 Let's consider five classes of people: * The institutional poor (e.g., the homeless, the chronically ill) are 0% producers, 5% consumers, 0% givers, and 100% takers.2 The amount of consumption they represent is negligible while as takers, they absorb vast amounts of resources. Or, perhaps more accurately, vast amounts of resources are consumed on their behalf — whether they benefit from that consumption is dubious. The institutional poor exist because there are always costs that exceed society's capacity to bear. The only stable means of support beyond frugal taxation is through charitable donation, but because there are always cases where people won't or can't benefit from the assistance to rise above this social class, the class will always exist in every society. Members of this group can rarely be elevated to other social classes.3 * The material poor (e.g., the uneducated, disenfranchised, debilitated, disabled) are 20% producers, 40% consumers, 0% givers, and 80% takers. That might be a particularly harsh summary as individual cases vary widely. Nevertheless, this class tends to hold minimum-wage jobs (low productivity) and yet want the benefits of greater affluence (medium consumption). They rarely contribute charitably due to lack of resources and/or time, but often rely on charity to help them overcome rising costs of living. This class is often better assisted to enter more affluent social classes due to judicious social programs that improve education and life skills. * The middle class are your workers. *This is incredibly important!* 80% production, 80% consumption, 50% givers, 5% takers. The wealthy of any society depends pretty much exclusively on the existence of this class. Farmers, miners, loggers, bakers, teachers, shop keepers, tailors, etc., etc., etc. Eliminating this class is always a really bad idea because perceived wealth often results in perceived entitlement. It isn't the wealthy classes that need to be expanded, it's this one. To use a phrase from The Scarlet Pimpernell: > > Chauvelin: We shall execute our king instead, sir, and exalt our tailors. > > > Sir Percy: More's the pity. Then your tailors will rule the land, and no one will make the clothes. So much for French fashion, and French politics. > > > * New Wealth are often industry builders (e.g. Steve Jobs). They became wealthy (and stay that way) by producing. 100% producers, 100% consumers, 80% givers, 0% takers. They build businesses, creat jobs, meet demand, and then continue to fund (both as investors and as philanthropists) production. These wealthy people are usually producers, consumers, and givers on a massive scale. * Old Wealth are often represented by "old money" heirs and heiresses (e.g., Paris Hilton), but not always. They are often 0% producers, 100% consumers, 40% givers, and 10% takers. I give them that 10% for being takers because these folks are frequently looking for loopholes to keep their wealth rather than opportunities to invest it.4 Yeah, yeah... but what has this to do with my question? Here are your problems: 1. You can't equalize people via money. As Dash said, it's "another way of saying no one is [special]." It doesn't matter if everyone has an equal income of \$1,000,000 or just \$1. By normalizing society you both devalue the money and remove the incentive for workers to work harder and the new wealthy to invest. Here's a key: it's the movement of money through an economy that makes it strong, not the amount of money in it. If no one is willing to make the clothes because everyone is wealthy, there's nowhere for the money to go, so you might as well equalize everyone at \$1. 2. You can't lift people with just money, either. This is the problem most people don't understand about arbitrarily raising (or using at all) minimum wages. It may temporarily lift people from the material poor to the middle class, but it does so by inflating the economy and devaluing the education that made the middle class what it is in the first place because you haven't made the material poor better producers. Production/productivity is the key! Not money. 3. Remember that "wealth" isn't about money, it's about luxury, influence, and power. A shop keeper can be those things, so can an industry mogul. But if you measure those things only by money it's impossible for the shop keeper and the industry mogul to have the same amount of money — or you've reduced the mogul to a shop keeper. So, the easy answer to your question is "no." You can't reduce or eliminate the middle class because those are the people doing the vast majority of producing in any country. If you try to make them wealthy, what you'll do is devalue the money such that it's not worth anything, thereby reducing the wealthy to the middle or material poor classes. So, look at wealth another way It is my recommendation that you stop thinking in terms of money and possibly stop thinking in terms of "fairness" or "equality." What you need is a society that's egalitarian in that everyone has access to opportunities that allow them to make the most of their abilities. What you want is for everyone to be productive. That's what makes everyone "wealthy." --- 1 The following list is not meant to be offensive, but a simple (and simplistic) set of descriptions. It could be considered brutal by some. I apologize if it offends. However, if you choose to complain, please help me find a way to express the ideas in an accurate way and not simply a more "politically correct" way. Clarity may not be sacrificed on the altar of vicarious affirmation. Thanks. 2 I've little doubt my percentages will cause arguments. No, I don't have citations that back them up. They're my "gut feeling" based on years of economic, community, and pastoral experience. If someone can improve the numbers, let me know. You'll note quickly that there isn't a baseline that "adds up to 100%." Maybe I'm wrong, but I've not found inter-social challenges to ever add up to 100% of anything. 3 It's their children who can be elevated. Once an adult enters this social class it is very, very difficult to lift them out again because there's often a systemic reason for them being in the class: untreatable illness or injury, mental limitation, behavioral institutionalization, etc. People have (nobly and justly) been trying to eliminate this class for... well... forever, with little success. A "just" society continues to make that effort anyway despite the cost, and improves socially by learning how to most efficiently balance cost with opportunity. Examples: educating the public such that more charitably donate to reduce the burden of all or improve healthcare efficiency to cover this non-paying class. 4 I loathe this class as much as I admire the "new wealth" class. Just in case I didn't make that clear. [Answer] This looks like a common situation with countries becoming quickly rich on natural resources, like Russia or Arabic oil-rich countries. The question is - for how long the country can prosper without a middle class. If working class conditions aren't improving (i.e. thee is no viable path to financial independence), its discontent would only grow, and government has to become increasingly oppressive. Providing a plenitude of low-paying jobs or government assistance can help, but only a little. In longer term, because upper class is unrestricted and country's fortunes aren't likely to grow forever, corruption should turn the country to a less affluent place with social unrest and possible revolution in the making. [Answer] You'll probably always have a local middle class even if they're loaded by the standards of their neighbours. If the local middle class is not defined by being the traditionally middle class, having more than the working class but not being rich, then they are defined by being the merely rich among the super rich. [Answer] You might enjoy reading [The Dictator's Handbook by Bruce Bueno de Mesquita and Alastair Smith](https://www.amazon.co.uk/dp/B06XBY3XJV/) which, among other things, attempts to explain why dictatorships in resource-rich countries seem so durable. It's [summarised in this video](https://www.youtube.com/watch?v=rStL7niR7gs). In particular: * You have a lot of GDP from natural resources (oil, diamond mines...) that the Glorious Leader can control easily and don't need lots of educated people. * Only a small fraction of the population has influence on who the Glorious Leader is (army chiefs, village heads etc) * The Glorious Leader gives that population quite a bit of stuff to buy their support. He'll have to spend quite a bit, as if he doesn't they'll replace him with someone who does. * The international community officially frowns on this, but unofficially it's much cheaper to buy your UN votes and suchlike with "development aid" because they only need to convince/bribe the few powerful people, unlike a democracy where they'd need to convince/bribe almost everyone. [Answer] Singapore model I could imagine a large impoverished rural nation with a single prosperous city that was very different economically from the rest of the nation. Imagine if Singapore had stayed in Malaysia. Singapore has 5.6 million people and a GDP of 65,000 - economically they have a lot of good stuff going on, and not by lucking into mineral wealth. Malaysia has 32 million with a GDP of 11,000; pretty different. But imagine if Malaysia were an agrarian nation more like Bangladesh: 162 million, GDP of 4000. The people in the city are not a rarefied millionaire class like in Monaco. They are well paid skilled workers, traders, bankers etc and in the city there is a middle class providing services to these people. The folks in the city would want to defend their good thing which they claim is the result of their hard work and enlightened policies. I could imagine it even being a walled city Constantinople-style: access to the city would be limited because the people in the countryside know that even the trash in the city is richer than they are. Re your religious nonworkers - if you are inspired by Haredim that is fine. You could also base your nonworkers on Buddhist monks and get the same point across. <https://buddhism.stackexchange.com/questions/24877/what-is-the-reason-why-buddhist-monks-dont-work-to-support-themselves-do-the-m> [Answer] Yes, and I can think of several reasons why, two being based on real-world countries/places I've visited. Some existing answers have made what seems to me an error of principle. They correctly point out that wealth is relative ("if everyone is rich, nobody is"). But the question doesn't ask about wealthy people, it asks about a wealthy country. It's a crucial difference. A country where everyone was equally rich, or very polarised between rich and poor, could still be a wealthy country. It could have rich natural resources, or a different culture, or longer established, or control some widely used technology, or dominate because of a religion it's established elsewhere in the past, or some such. So it would be a wealthy country, and yet might not have a middle class nowadays. So we have to consider how a country might have gained long term stable control or access to something cultural or tangible, of any kind, which means it no longer has a middle class, but it has quite universal wealth, or large surplus of national income beyond national budget expenditure, or large per capita assets, compared to other countries. # Underlying reasons * Colonialism/religion. It has left other nations paying tribute, and to prevent internal upheaval, has gradually moved to a state of internal equality among its own citizens. Other countries pay taxes/tribute, they just receive it. Their policy decrees are followed by everyone else and would be unthinkable to break, from tradition or from fear of what they might do (even if it's a hollow belief). Not much production these days. * Unique role. They "speak to the gods", or are traditionally a nation of priests, or the world has reached peace because everyone funds this country which has become the sole monopoly provider of dispute resolution between other powers. Or they are academics, and develop knowledge that all gain from. * Low expenditure. In combination with other reasons why there's a small middle class, it could be that the country's leadership style values frugality. No healthcare, let people die; no need to travel much, we have enough here; no military, we are pivotal enough in some way (see other bullets) that no country will allow any other to invade or gain undue influence, or we have some technology they don't, which negates the need for defence, or we have a social contract that anyone who invaded would end up with only a Pyrrhic victory for some reason. * Monopoly over a resource. Some resources are limited. Set in today's world, if a country has some rare mineral ore that's essential for industry (rare earth's, as in the news, or intellectual property as in the current Qualcomm dispute also in the news), then they might simply license others to mine/use it, avoid all the heavy work, for a monopoly license fee. If the ore or whatever, is essential enough and the pattern is established early and then grows, the economy will simply "grow that way" - they will reap ongoing fees, check who is taking/using how much, and enjoy the income. If wise perhaps they distribute it equally. So there's no privileged class, hence little middle class, but it's definitely a very rich country. (Perhaps, following the Qualcomm example, they have developed some area of technology which they alone hold IP rights to; their leverage has allowed them to pressure all other countries into accepting laws that would let them hang onto their control indefinitely and act on any attempt to bypass it.) # Two real world cases The real-world examples I mentioned are of this last kind. In the middle of the Pacific Ocean, lies the widely dispersed island group of Kiribati. It's a bunch of tiny atolls thousands of miles from major industry, and unable to support any of its own. Coral and a smattering of mangrove+coconut trees aren't exactly great for any kind of valuable production. But the islands are definitely wealthier than you'd think. They have a university - well funded and comprehensive. They have free public healthcare including air ambulance between islands. They own, under international law, some huge swathe of the Pacific, as territorial waters - something like 2 million square km if I remember correctly, and they license it to other countries to fish in. Even given illicit fishing, they have a continual and large income. They're wealthy. They have a very simple cultural lifestyle without much consumption, and few tourists to push up prices or introduce inflation via marketing, so they also don't have a societal demand to spend much compared to some other countries. They would not need to develop or retain a middle class to enable them to remain a relatively wealthy country in future. It wouldn't take much to imagine that they could could lose almost whatever middle class they have, and still remain a wealthy country, or individually have comparative wealth if they travel overseas. So that's an example. Disclaimer, that was some years ago, might be the same now, might not. Probably is. A second near example is found in the Shetland Isles in the UK, which - when North Sea Oil was discovered - turned out to be such a valuable place to locate onshore oil platform support, of the few islands in that area, that they could demand very beneficial terms. The oil companies were - excuse the pun - over a barrel. Again, it's a much richer place than you'd expect for its size and resources. Add sovereignty and oilfields that last centuries not decades, and allow the middle classes to fall away as people enjoy the income benefits, and it would be similar. [Answer] Maybe the most straightforward way to model a society without a middle class would be to use earlier feudal societies, before the emergence of middle classes, as a template. In that structure you have Nobility (who own all the land) and serfs (who own none of the land, live on the land owned by the nobility and pay rent to the the nobility). If you can imagine conditions that would allow this setup to exist in a contemporary, wealthy country then you may be some way towards creating the country you alluded to. [Answer] Probably not, on several fronts. Mechanized agriculture is going to be a problem. Mechanized agriculture requires a large technically-savvy infrastructure to develop, manufacture, and support the machinery, and a large transportation infrastructure to distribute the produce. Mechanized agriculture would seem to imply mechanized transportation. None of this is likely in the absence of a middle class. Unless you're going to wave your hands very hard, mechanization doesn't occur when the mechanics are blacksmiths. In order to be efficient, you need common standards to make interchangeable parts, and mass production. Equally, the presence of a large dole population requires significant bureaucratic resources to administer the distribution of wealth, yet you've postulated a very small public jobs force. And the presence of this dole population implies that the economy as a whole is very productive on a per-capita basis. The agricultural practices are likely to need artificial fertilizer to do this, and this requires more physical and intellectual infrastructure. [Answer] @Xplodotron, has two potentials. Another possibility is a high tech society where distribution of goods is automatic. Think of a totally automated Amazon run by an AI. There is no one to make money collecting goods and reselling them. This pretty much does away with the middle class. The wealth issue can be handled by how evenly the goods are distributed and where the goods come from. This will work best if the sources of the goods are 3rd world countries. That way, the wealthy nation can retain its wealth by paying as little as possible for the goods. This is generally what Monaco does with it's labor. Being a conquering nation is good for its citizens so long as the conquered do not become citizens. [Answer] Is it possible to have a wealthy country without a middle class? This question could be answered in two different ways. A society with just rich and poor without a middle, or a society where the gap between rich and poor is small enough that a middle may not be a meaningful distinction. Society lacks a middle because the gap between rich and poor is too great, or too small. Both are possible. The Big Gap In order to understand how society could become more stratified, we have to understand the origins of the middle class. In medieval Europe at least, the vast majority were illiterate peasant farmers. There was a small middle class, mostly skilled labourers; from merchants to masons, scribes to smiths. European society was feudal for centuries, and in this system serfdom was standard. Peasants were legally tied to their land. Land was owned by the monarch, who gifted estates to nobles as payment for loyalty. After the Black Death in the mid 1300s much of the European population had died. Those who survived inherited more land and were better able to negotiate wages. This meant that serfdom became less strict in Western Europe, allowing greater social mobility and a larger middle class. In the east things went the other way. The death toll from the plague in what would become Russia had been low compared with the Mediterranean, and consequently the social order was unchallenged. This allowed lords to enforce progressively stricter laws which segregated peasants from nobles. Eventually by the late 1500s Russian peasants were both an asset which came with land ownership, were forbidden from leaving their land, and could not move up the social ladder. This resulted in a smaller middle class with minimal social mobility. Thomas Piketty's 2013 analysis of the history of capitalism ([Capital in the Twenty-First Century](https://en.wikipedia.org/wiki/Capital_in_the_Twenty-First_Century)), from the industrial revolution to modern day, concluded on a simple reality: private wealth grows faster than the economy. Thus, naturally inequality grows over time. The growth in inequality tends towards the stratification of society, but we have to understand what makes society more or less equal economically. The Small Gap Over the last century those societies who have seen the greatest improvements in living standards and the greatest decreases in inequality have invested in their citizens by enabling commerce and providing welfare (education, healthcare, unemployment benefits, etc). Amongst developed nations differences in inequality exist. Some have considerably more (UK, USA, Portugal), and some have considerably less (Sweden, Japan). This is detailed by Richard Wilkinson and Katie Pickett in their 2009 book on inequality, [The Spirit Level](https://en.wikipedia.org/wiki/The_Spirit_Level_(book)). One notable observation is that society can reduce inequality with different strategies. Sweden has a much greater difference in pre-tax incomes, but that difference is moderated by tax and spend. In Japan, which has similar inequality to Sweden, the difference is owed to the fact differences in pre-tax income are lower, as Japanese employers do not pay their bosses in excess of their workers. If an economy is focused on traditional sorts of primary or secondary labour (extracting resources and manufacturing), instead of tertiary or quaternary labour (services and knowledge), then most people will have working class jobs. This allows you to choose whether workers are paid less or more than average, and consequently whether the middle class is small because working class jobs are plentiful and well paid, or because the economy is stagnant owing to a lack of opportunity. It's also worth pointing out that GDP per capita may be deceptive, as you could have an exceptionally wealthy elite, ruling over an impoverished majority, and still have a seemingly high GDP per capita if they are sitting on some sort of enormous mineral wealth; gold, oil, etc. [Answer] Suppose, entirely for the sake of argument, that such a fictional country exists. First, it would need to have killed off all its industry - outsourced most of it to third world countries where labor is cheap. This way the large, uneducated mass wouldn't have access to the once plenty, well-paying blue collar jobs and would be kept poor. Relegated to a life in the low-wage, long hours services industry if they're uneducated. Second, it would need to have placed college education at such a premium - say 40,000 - 50,000 USD a year - that it's comfortably out of range for most working-class families in the fictional country you described. This means your youth, mostly sons and daughters of the working middle-class, generally won't have access to a tertiary education. Worse even - if they do decide to go ahead with it, they're kept in bondage, in the form of student loans, for the rest of their adult lives. This will ensure the elites, and only the elites, can send their sons and daughters to college, and therefore manage to stay educated and powerful. Third, it would need 'low taxes' - but only on the rich. The government is, after all, pretty much the only body capable of bridging income inequalities and redistributing wealth - so you wanna keep it as underfunded as possible. That means things like universal health care and a decent public transportation system are all also out of reach, further compounding the burden you place on your working-class citizens. Last, but not least: you want a fanatical, partisan media. Day in and day out, addressing the wrong problems - trying to make it all about 'personal freedoms', or guns, or foreign wars, or terrorism. Never about the clear elephant in the room which is the mounting income inequality. That would work to really drive the point home, and make sure that the rest of your citizens are kept well in the dark and alienated. Such a country would be rich sure, even prosperous, but it would have no middle class, and would also be one of the most unequal countries in the developed world. Ring a bell yet? [Answer] I'm not sure that what you ask is statistically possible. If we define middle class purely by the income, then you will have a gaussian curve of income. Wherever the peak of the curve is, there is your median income - majority of people in your society will have an income nearest to median - and that will be your middle class. It's very improbable that a natural distribution will have anything but a gaussian curve when charted. The nearest variant I can imagine is to have a curve with two peaks - that would mean, actually, two curves superimposed. And that would mean two economic systems that exist in the society with barely any contact. I'm not yet sure how that could be. If we mean 'middle class' as social or cultural term, then yes, it's possible. Such terms are often used as forms of self-determination, so if your society thinks being 'middle class' something abhorrent, then people with median income will try to call themselves by some other name. ]
[Question] [ If a bank wanted to operate branches in multiple cities, possibly separated by large distances, how would they prevent a fraudulent customer from double-dipping on a withdrawal? For example, if I have $200 in the bank in Town A, I could go in and withdraw it. As soon as I get it, I rent a horse (/some other form of transport) and go to Town B, where there is another branch of the same bank. If I also try to withdraw my money there, how will they know that I don't have the money in my account anymore? Electricity has not been discovered yet, and so clearly electronic forms of communication can't be used. Is there any way for the branches to keep their records synchronized in order to prevent this kind of fraud? One thinks perhaps of communication system like flags or other visual signals, but in this case the bank is sending rather complex information, and I think it would be difficult to encode this sort of info into a simple, visually-based communication system. [Answer] Fortunately for you, to answer this question, we can simply turn to the past, instead of reinventing the wheel. Fortunately for me, people have already typed up fantastic, simple explanations of the previous systems, so I won't have to reinvent the wheel. [Jacob VanWagoner on Quora](https://www.quora.com/How-did-banks-work-in-the-past-before-the-arrival-of-the-computer-age) already provided us with the following: > > People transacted in bank notes. Long before the creation of > currencies like the dollar, back when all money was gold, they still > had banks. When you deposited your gold in the bank, the bank > extracted a small fee for the use of their service, then handed you a > note or set of notes that would allow you to come back and exchange > the note for that specific weight of gold. It became much more > convenient to exchange the notes, since they were ostensibly > equivalent in worth to the gold since they could be quickly exchanged > for it. > > > On the other side of the counter, how the bank kept track of who had > what, all accounts were written in a ledger. When you made a deposit > or a withdrawal, the bank's book-keeper would write in a note about > the transaction including how much was deposited/withdrawn and the > total remaining in the account. > > > Without long-range instant communication, the accounts were tied to > the local bank branch and you had to physically go to the bank to > exchange money out of it, and without being able to do so you would > have to just carry the bank notes or other currency. > > > For exchanges between banks, it got more interesting and required the > formation of fungible currency -- that is, notes that would be > accepted by multiple banks. When there was a transfer of funds > requested by bank notes, often there would have to be a physical > transfer of property done at a later date. With fiat currency, such > physical transfer was unnecessary, only the transfer of the notes. > With invention of the telegraph, one could instantly communicate over > a wire to "transfer" "money" (hence the terminology "wire transfer"). > (I put the words in quotes because there was no physical transfer at > all, just writing down the amounts from one account to another. Since > most of the money was just stored in the bank, the bank didn't > actually need to physically hold all the money in the accounts). > > > In response to your other questions: "If there are recorded booklets > to carry, would those be easily fraud?" Yes, it would be easy to > falsify information in a ledger. It was therefore required by law to > keep accurate ledgers, and they would be audited periodically. If a > clerk misplaced a ledger, that could spell legal doom for a merchant > or a bank, since it contained a record of all transactions. They were > checked as often as could be permitted for fraud. > > > "Since the tellers of the banks directly handles moneys given to them, > would it be prone to corruption from stealing money?" Yes, they could > be prone to corruption from stealing money. That's what ledgers were > for, incidentally. People feared their money would be stolen, or that > the notes could be counterfeited. Any suspicious behavior from a > banker (such as being ostentatious) would draw attention, and the law > would be swiftly applied, quite possibly by a lynch mob or vigilantes, > to any banker who could be shown to be messing with the books. > Further, they feared 'runs' on the bank where more people would come > in and demand their money / gold than the bank actually held, which > would happen if any of those rumors started circulating. > > > It gets even more interesting when you consider the process of loaning > money, in which an account is created and money "deposited" in the > loan account. Given the circulation level (how many exchanges are > actually done with money held at the bank), many bankers found they > could create as much as 9x the money they actually held without being > found out. This practice still exists today in the form of fractional > reserve lending, and it is codified in law. > > > Thanks Jake from State Farm. [Answer] Nex Terren answered well, but I also want to mention fraud protection. Until the late 1800s, international banks were family banks. From the Peruzzis and Medicis of Florence in the Renaissance, to the Fugger's that bankrolled Hapsburg wars of the Reformation, to the Rothschild's and Barings of the Industrial revolution, banks worked on families. Since all the bank branch managers were sons, brothers or cousins, they tended to know all the other branches customers, personally or through correspondence. For example, when Salomon Rothschild wanted to arrange a British loan to a Prussian client, he wrote his brother Nathan, in London, a letter saying so. Then when the Prussian showed up with a bank note, Nathan was confident he could honor it. For the first 400 or so years of banking, it was a private, family oriented, interpersonal affair. [Answer] The answers on previous bank systems (I refuse to say "old" since they're within my lifetime!) are good. I want to add one aspect to history: modern cryptography. The question asks us to forego high-speed comms. But we could still advance mathematics. Many of the old ledger systems could be vastly improved with some cryptographic signing. Letters of credit of yesteryear were authenticated by hard-to-forge signatures and seals, but they could have been mathematically signed. You need electronic computers to handle the giant bit strings we use today, but you could get away with much smaller keys if you only had humans as computers (yes, that used to be a job title). Crypto keys could allow a person with a line of credit at one branch to get a key from that branch and then redeem it at another branch much more securely. The banks themselves would worry about reconciling hard currency every few months. [Answer] This is pretty much what "cheque kiting" is. This was basically the operation of all banks up to the invention of the ATM and real-time transaction processing. Turning it into actual cash depends on the exact operation of the bank. You can write out [a cheque to 'cash'](http://forums.moneysavingexpert.com/showthread.php?t=3974839), but most banks won't hand over the cash unless you present them with ID. So suppose you do that at bank A, and bank B. What happens? Nothing, until the cheques clear. "Clearing" is the process of updating the account status with the transactions as the cheques make their way back to the originating bank by post. Once the cheques clear you have -\$200 as a balance. This is an unauthorised overdraft. You've not even committed a crime at this point, and most banks will just let you do it so long as you pay back the \$200 and some fees. Doing it without intention to pay back the bank is fraud, but that's why they have your ID on file. A little detail from a historical novel, Walter Scott's Rob Roy. At one point the protagonist goes to the post office to pick up his mail, having been sent to rural north England. He recieves a letter from his father with a "goldsmith's bill" attached, which is effectively a bearer cheque that he is able to turn into gold in a nearby town to fund his continuing adventures. Just like Western Union avant la lettre. [Answer] The simple way this was done historically was that you had a small book which was a record of the transactions going through your account. Every time you pay in or withdraw money it it's noted in the book so it is essentially a manual equivalent of a debit card. Even relatively recently building society accounts often had account books. The earliest proto-banking systems used letters of credit which were essentially a written confirmation that you had deposited x amount of money or valuables with a bank. These eventually evolved into banknotes and cheques. It's also worth bearing in mind that in the early days of banking bank accounts were really only for the moderately wealthy and a lot of store was set on personal reputation and informal credit with individual tradesmen and shopkeepers was a lot more common. It's also not that long ago that you could be put in prison indefinitely for a bad debt. The other aspect of this is that when you first open the account you have to prove your identity and bona-fides so even if you get away with the fraud at the time you're going to get caught eventually. Equally it is entirely possible even now to write a cheque that you don't have the funds to cover, but it is illegal to do it knowingly and the bank will know that you have done it sooner or later. Similarly, historically individual bank branches had a lot more autonomy so any transaction which was even remotely unusual may well have been passed to the manager who was most likely very experienced and would make a decision based on their own judgement. [Answer] If you are planning to devise a banking system for a world without quick communication, historical record show how banking systems used to work. First thing to understand is that ordinary people would not use banks, nor generally coins. In a given area (village, town), shopkeepers (and sometimes families) would use tally sticks to keep track of who bought what and when. You would go to the baker, take your weekly stock of bread, and they would notch the tally stick. When the baker goes to the mill, the miller records a notch on the baker's tally for each flour sack. And so on so forth. Once a year, generally on St Martin's day, everyone would reconcile the accounts, and settle the outstanding debt. The one who had coins could use them, the one who didn't could use anything to settle the debt - maybe they would give a pig, or anything of value they would have. Only wealthy people and merchants would use banks. But again, not like we are used to think about it. Let's say I'm a wealthy individual, and I need to travel. I know that at my destination I will need funds to sustain my standard of living. But, I don't want to travel with money, by fear of being robbed. Then, I can go to a bank branch, deposit some value (coins, or a few bullion of precious metal for example). The bank will issue a note, telling the remote branch that it has to pay the bearer of the note the same amount of money in local currency. When reaching my destination, I can then go to the bank branch, give them the note, and withdraw the written amount of money in local currency. Deposit accounts (i.e., accounts you described where you would deposit money and withdraw it at any time, anywhere) could only work in a local branch, where employee knew who you were were and would keep track of deposit and withdrawals on a local ledger. If you were to go to another bank branch in another town, they wouldn't know who you are and there was no way you could withdraw any money. Also, keep in mind that until late in the 20th century, there was no government issued IDs. There was absolutely no way to know if you were who you pretended to, unless by chance someone well known in the area could vouch for you. That is why introduction letters existed. For example, if you planned to go to a specific town, you would look around for someone who knew you well enough, and personally knew someone in this town. They would then write you an introduction letter. Upon arrival, you would go to their remote contact and give them the letter. If convinced by the letter, they would they be able to vouch for you, and confirm to locals that you were who you pretended to, because they trusted the person who wrote the letter. In summary, a world without quick communication is exactly our world a few centuries ago, and you can draw from historical records to devise your system. If you want firsthand accounts of how it worked, Casanova's memoirs for example are a good place to start. [Answer] This is a very interesting thread. Sorry, my reply is short but have you thought about homing pigeons? Banks could keep a pigeon aviary and routinely dispatch some to all their sibling branches. At the end of every day, or maybe twice a day, every sibling branch got updated with account modifications for the day, from every other sibling branch. The banks would have to maintain aviaries at every branch, and cover the cost of deploying these pigeons to every other branch, every so often. Rothschild had a pigeon aviary, and in fact, used a homing pigeon to intimate himself about the result of the battle of Waterloo a full day (or two) before the rest of Britain. This was how he was able to manipulate the stock market and become the richest man in the land. [Answer] Whenever you want money from your account, you have to bring in the receipt with the current balance from the last time you accessed it, in exchange for a new receipt. To commit a fraud, you'll have to forge the receipt, which is heavily punished in any (pre-)modern state. If you loose it, you have to wait until messages have been requested and come in from all dependencies about your last transaction. [Answer] [![Bankbook](https://i.stack.imgur.com/J46Z3.png)](https://i.stack.imgur.com/J46Z3.png) (from Wikipedia) Some banks (still) use passbooks to record all transactions. They are are passport-sized booklets recording all the transactions in your account; they are normally used for savings, rather than day-to-day accounts. IIRC, they used be authoritative on the how much money is in your bank account; nowadays they are a copy of the computer record. There is no reason why a medieval bank could not use a combination of passbooks (kept by the customer), and ledgers (kept by the 'home' branch, with weekly reconciliation from other branches). [Answer] The solution given by Nex Terren was used in the common law (England and its former colonies) territory. Elsewhere, they used the equivalent of a money order. The bank would confirm that you had the money, then remove the money you were transferring from your account, then you would send the money order to somebody else, who could deposit it at their bank. The receiving bank would then only bear the risk of forged instruments and of a default by the sending bank which would generally be much more credit worthy than the customer. Cashier's checks, certified checks, money orders, electronic funds transfers, and giros are all essentially different ways of describing this same transaction. A similar device which also trades the creditworthiness of the bank for that of a customer is called a "letter of credit." In a letter of credit the bank promises to pay a certain amount of money upon the meeting of a condition, normally the presentation of some sort of document such as a release of lien or a warehouse receipt or a bill of lading showing that good have been dispatched to the buyer. The customer satisfies the local bank that he is good for the money (perhaps even depositing it in a special account that the bank controls for that amount of money) and the person induced to take action by the letter of credit only has to know that the bank is good for the money, not that the customer is good for it. ]
[Question] [ One of the races in my world is a fox-people. They are basically small humanoids with a few vulpine features, including ears and a tail. They live primarily in a sub-arctic climate, where their additional fur is a benefit. Technology is very roughly 16th century European. I had imagined there were individuals of other races (let's just say humans for simplicity) who would also be living in the same region. Initially I had pictured these individuals as the equivalent of [mountain men](https://en.wikipedia.org/wiki/Mountain_man), living off the land and dressing in furs they had trapped. This, however, presented the question of how their dress was perceived. On one hand I can see how this would utterly horrify a people who also had fur. However, then I thought about how (most) humans are not bothered by leather goods, despite also having skin. So the question is, would the fox-people be offended by fur clothing? [Answer] "What, can't you tell the difference between fox hair and human hair?" There are [many types of fur](https://en.wikipedia.org/wiki/List_of_types_of_fur), with varying qualities, such as thickness and length. Further, fur is indistinguishable from human hair on the structural level - that said the expression of hair and fur varies greatly between animals. Humans consider their hair different from that of other animals, just as we consider human skin different from that of, say, dolphin skin (even though both are mammals). We make these distinctions readily, and there is no reason an intelligent race of foxes would not. Thus, it is unlikely that wearing a bear pelt would be any more offensive to them than wearing a human pelt. Wearing a fox pelt probably would be offensive, just as wearing a human pelt (or [human scalps](https://en.wikipedia.org/wiki/Human_trophy_collecting)) is offensive to humans, in general. That said, some of the race probably wouldn't take offense, just as some humans seek out such trophies. Likewise, some members of the species are going to take offense at the bear pelt - but probably in fewer number and attached to a concern that is different from raw existential disgust. In this way they'd be similar to human PETA activists. In short there is going to be a spread of opinions, and a spread of ability to distinguish particulars about a given pelt or skin. It is unlikely to rise to a level of a species-wide more unless there is another instigating factor. As a comparison, take widely varying opinions on what is taboo food to eat in human cultures: each of cow, scorpion, beetle, dog, monkey and human is acceptable to eat in some places and not in others. The widespreadness of those taboos is in part proportional to their closeness to human-ness, and in part their closeness to other-ness, but all are accepted in places and rejected elsewhere. [Answer] This seems more like a society thing than a species one. As you said yourself, humans have skin and most aren't offended by leather, which is derived from the skin of animals. I'm sure your world may contain fox-persons who are offended by fur products, but I'd rather think fur products would make a great societal/fashion statement. Foxes are omnivores, like humans. Presuming the fox-people follow the common diet of the fox, they eat meat. A number of humans prefer to hunt their own meat; no reason fox-persons wouldn't also. Since it's unusual to eat fur (seriously, I can't find a single article online stating whether it's safe to eat fur), the fox-people could just as well take the fur and use it as a symbol of their hunting prowess: "See this cougar fur? Yeah, I killed the cat myself." If your world has both fox-people and foxes, killing a fox may be a taboo in some cultures, just as some human cultures have a taboo about killing apes or monkeys. [Answer] Humans are not offended by leather when we have skin, but leather does not look like human skin. Perhaps the Fox people would find untreated fur clothing offensive, or they might even only think that red fur is wrong. [Answer] Probably not. We wear leather, and we have skin. Your fox people know the value of fur in a cold climate and probably have beauty standards related to their fur, so I think they would understand other species/races wearing furs for the same reasons. They also won't necessarily see themselves as animals or animal-like, even though we or other species/races in their world would think there's an obvious connection. They would certainly have a problem with their fur being worn by others, just as we cringe at the idea of people being exploited as a resource. [Answer] There was some flavor text on a Magic card that I will sum up. Essentially it would be worth your life to wear lizard skins in the desert because the reptilian people living there were mightily offended by it. I found that to be incredibly absurd, and compared it (as you did) to mammalian races wearing leather. That being said, how similar would an item made of fox fur appear compared to the same item were it to be made from the skin of your fox-people? If the similarity requires a second look or deliberate study to tell the difference, this may be quite offensive. This may increase to a fatal mistake if there is history of fox-people actually being "harvested" for their fur. --- The actual quote on the "Viashino Warrior" card is: > > When traveling the Great Desert avoid wearing the scales of lizards, for the Viashino rule the sands and look poorly on the skinning of their cousins. --Zhalfirin Guide to the Desert > > > [Answer] As other answers flesh out human based and non-human based leather are very different things only to humans. If they are not vegans they probably aren't going to get that upset by seeing dead animals. Then again if they are content to always dress in their birthday suits it might strike them as icky to have something dead hanging about all the time. They might think Humans trying to look like them is flattering, or maybe a little silly. In the 16th century the locals of various non-Europe places (who were often comfortable mostly in their own skin) thought the European's choice of clothing non-obvious. Everywhere I'm aware of has a tradition of mocking their neighbor's costume that seems to be irrespective of what the costume is or how close it is to their own, but generally the offense of it doesn't last more than a generation of contact. [Answer] Why would they be offended? If they're fox-people, that means they're intelligent carnivores. They will not be vegetarian, and will most certainly eat furry mammals with much delight. If you want them to become offended, weirded out, or sickened by people wearing food, then that might work. But even if it was foxfur from feral foxes, to them it'd only be about the same weirdness as seeing someone wearing a monkeyskin is to us. They're very unlikely to relate to their unintelligent brethren unless there's some religious aspect making killing them a no-no. On the other hand, cultural history could have men killing and skinning them, so humans wearing fur could be seen as a huge slap in the face. Most societies are for the most part reasonably tolerant of such cultural differences, though, and will just point it out and laugh at the ignorant outsider. To me, an over the top, pitchforks-and-torches reaction, would feel a bit like you were straining believability for the sake of plot. [Answer] In the real world, there are humans who are offended by leather and fur clothing, and humans who aren't. There are even businesses which make articles of clothing out of human leather, even though this comes from willing participants upon their deaths it's obviously a lot more more controversial though is accepted by some. Similarly, the thought of wearing shoes made from bonobo or orangutan leather would likely provoke more hostile reactions than those made from cow or pig leather. But it really boils down to their culture. If they're a sub-arctic species they won't necessarily have a lot of luxury and may be fine with it. That said, their views on some kinds of fur may be similar to modern IRL humans views of primate leather. At a guess I would balance it somewhere between modern human views on primate leather and pragmatic acceptance. Perhaps it's looked down on, but not outlawed because dammit subarctic climates are cold. [Answer] You could definitely go either way with this one. On the one hand, humans eat chimpanzees, and seem to have no problem with that. On the other hand, if aliens came to earth and started eating chimpanzees, we might react a little more negatively, given their status as outsiders. You could also: # Make the animals sacred Hindus are offended by eating cows, even though they don't consider cows to be their "cousins." Maybe your fox-people believe that fur is a spiritual thing, that the soul resides in the fur or something, but it's not even strictly necessary for this scenario. [Answer] Probably not. They are, after all, carnivores. The thing that might get dicey is that by wearing fur, humans look more like the vulpines. This may be discouraged or even forbidden if the culture or government wants to encourage separation. If vulpines and humans normally live in separate areas, fur-wearing might be forbidden to humans in human areas as part and parcel of keeping people from adopting foreign ways rather than the age-old customs of humanity -- and in vulpine areas to prevent their assimilating in part and then corrupting vulpines into adopting foreign ways rather than the age-old customs of vulpinity. If they live in the same region and one is the ruling class, and the other subordinate, fur could be forbidden, either to keep superior humans from sliding into the corrupt low-class customs of the vulpines, or to keep inferior humans from aping their betters. ]
[Question] [ Brief setting notes: it's a "basically earth" type situation, a spinning ball of rock in space with the same size and gravity and atmosphere and magnetic fields and everything else. The main difference is that there is also a HUGE dungeon-cave system across the continent. No one knows how deep it goes, or how extensive it is. People have been exploring it for hundreds of years, using it for travel and trade, towns have been built around the entrances, and decent amounts of society and industry are built around it. But because of how large it is, and how inherently difficult it is to navigate in caves, only tiny fractions of it have been mapped, and what lies in the deepest depths is largely unknown. Things are about at a 1890s level of technology, and many people are all trying to solve the problem of underground navigation. When you're travelling underground for weeks and months at a time, knowing where you are can get almost impossible. Compasses help, but they only do so much, and there's no sun or stars to help determine latitude, to say nothing of longitude or altitude (which is often what people really want to know, no use in bragging about how you've been deeper than any other explorer if you don't know how deep you actually are.) So, given the technology that would realistically exist at about this time, is there some sort of surveying method or mechanism, portable and handy enough to be carried with the average explorer, which lets them know exactly where they are in terms of longitude, latitude, and altitude? [Answer] Altitude (or depth) can be measured with a barometer. Latitude is doable, but tricky. Two methods come to mind, but they require staying on one spot for rather a long time to make accurate measurements. The first option is to use a [Foucault pendulum](https://en.wikipedia.org/wiki/Foucault_pendulum). The rate of precession of such a pendulum is directly related to latitude; the pendulum conveniently serves as its own timekeeping device, so you don't even need a pocket watch to go with it. A protractor and a single-sheet conversion table would be sufficient. You just have to hang around in one spot long enough to get an accurate measure of the precession rate, which would take several hours at least, and while it could be packed down quite compactly for transport, the device would be rather tricky to set up. The second option is to use a gyroscope. This would be slightly past the level of technology that gave us pocket watches for measuring longitude on Earth, to be able to use spring-driven clockwork to keep the thing spinning long enough, and on sufficiently free bearings. The basic idea is to start the gyroscope spinning, and then observe its apparent axis of precession over a significant portion of a day; the gyroscope will maintain a constant orientation in space while it is transported along by the rotation of the planet. The precession axis is parallel to the axis of the planet, and the angle it makes with the direction of gravity tells you your latitude. It is a good idea to run at least two gyroscopes in parallel, at ninety degrees to each other, to get a better reading, although with sufficient development it is possible to build damped gyroscopes which will naturally align themselves with the precession axis, making taking a reading much easier. Unlike a Foucault pendulum, a gyroscopic device will also indicate north and south--hence the name [gyrocompass](https://en.wikipedia.org/wiki/Gyrocompass). Longitude is much harder. Pocket watches don't do anything for you if you can't measure local solar time. Odometers could be used to assist with dead reckoning. Compasses might actually be useful in this regard as well; if you can establish a depth, latitude, and orientation to true north with a barometer and gyrocompass, and have a detailed magnetic declination map developed on the surface, you could simply consult the table of magnetic declinations along your line of latitude to narrow down options that match your magnetic compass reading. With a combination of pocket watch and really good gyrocompass, however, you can do better. To make this work, you will need an extremely accurate gyrocompass set rotating at a known position (say, when you enter the dungeon system) exactly perpendicular to the planetary axis. If you were to stay in one place, it would appear to rotate at a known rate as the planet spins, making one full rotation every day, so you can compare its actual rotation with that predicted by your pocket watch. If you stay in one spot, they will match exactly--but if you move east or west, they won't. The difference in the actual position of your gyrocompass at any point from that predicted by the pocket watch will indicate transport around the planet's axis farther or lesser than would be accomplished by the planet's own rotation--and thus, indicates how far you have traveled across the planet yourself. Essentially, the gyrocompass replaces the sun as your indicator of local time, to compare with time at your starting point as indicated by the pocket watch--with slight differences in time-interval-to-longitude conversions since the position of the sun tracks, well, solar time, while a gyrocompass tracks sidereal time. [Answer] People on the surface or at established underground settlements could set up "thumpers" which are massive weights that are raised and then dropped great heights according to a predetermined time schedule. With an exact enough seismograph (paper and pen), cave explorers could triangulate with a good clock and regular "thumps" happening around them. [Answer] > > is there some sort of surveying method or mechanism, portable and handy enough to be carried with the average explorer, which lets them know exactly where they are in terms of longitude, latitude, and altitude? > > > I am afraid that, if you can't rely on stars to determine your position and you really want/need to know it, you will be forced to constantly use a theodolite to triangulate your position with respect to some known location. Your entrance point will be the one having coordinates measured with respect to the stars, and from that on you will proceed by marking and measuring successive points. [Answer] For quick and easy reference? No. For slow and methodical surveying? Yes. You could have markers in the form of rods painted with alternating bands of colors and use something similar to a theodolite to measure compass bearing, angle of inclination from point to point. With a stadiametric rangefinder integrated into the theodolite scope, you could calculate the distance to the rod marker based on what size its image appears compared to the etched lines on the scope. This way, you could map out the cave painstakingly point to point, calculating position with trigonometry. Marking paths with markers, etc. [Answer] While I don't think this is the best explanation for how to determine position, I think it's a worthwhile idea and I'm putting it out as a suggestion. If it's really important that your explorers be able to work out their location underground for the plot of the story, you could build in some regular-period known seismic wave sources that let you triangulate your location. These could be set up by governments or explorers' associations or whatever – large beacons that emit a regular pulse of low-frequency seismic compression through the Earth. That way, you can triangulate your position by looking at a sensitive seismograph. Here's how it works: 1. You set up the seismograph and watch the path traced by the needle 2. The needle swings up and down in regular seismic waves. You record the time interval between two consecutive waves and the height of each wave: [![enter image description here](https://i.stack.imgur.com/VngkF.png)](https://i.stack.imgur.com/VngkF.png) Above, there are two waves visible, one with period T1 and one with period T2. 3. You look up the time period of each wave in an index table. The table contains data specifying the intensity of each wave at its source, as well as the geographical position of the sources. 4. You compare the intensity of each wave with its source intensity. From the amount by which the intensity of the wave has decreased, you can calculate how far it has traveled. Once you know how far you are from 4 or more sources, you can calculate your exact position in 3 dimensions relative to the sources. 5. Using the known locations of the sources, you can then calculate your coordinates using trigonometry. Yes, this requires a lot of setup. But since this technology would be difficult to acquire in the far distant past, it could be a useful way of explaining why it is only recently that explorers are able to navigate very deep below the surface. This means that there's a lot of unexplored, but explorable, territory. Essentially, humans were unable to navigate the cave systems for a long time until these beacons were set up. Now, caving is much safer and more profitable, and explorers are able to go to depths previously thought to be unreachable, because the beacons allow precise navigation. Also, the signals get weaker farther away from the surface. So beneath a certain depth you have to keep coming back up to get a reliable signal. As long as the cave systems are connected by the same body of air, you should be able to work out depth using a barometer, so that would be possible. [Answer] All of those would be affected by limited precision, but still workable: * Latitude - by the [direction of the magnetic vertical component of Earth's magnetic field](https://physics.stackexchange.com/questions/387744/vertical-component-of-earths-magnetic-field). That would require some well balanced magnetic needle and knowledge about the magnetic ore deposits (one may map them on the surface). * Altitude by air pressure. First order correction based on the latitude, to account for the varying thickness of the atmosphere due to Earth's rotation * Longitude - that IS hard. Other than the dead reckoning method... ummm... since you supposedly already mapped the magnetic ore deposits for the surface, can their position be used as "passive beacons" or "magnetic geo map"? Maybe some infrasonic beacons on the surface and some "time-of-flight" triangulation? [Answer] In 1890 there WAS some kind of radio. Directional antenas are not much of a high technology and they could be invented and developed then if there were demand. So, for low enough frequencies (in order for the waves to enter underground) and away from large iron ore deposits, you can get a rough estimate of a direction to a known radio station(s). See "ham radio fox hunting" or just abuse them as a "radio-stars" to navigate by. The deeper you go, the better your receiver has to be. If you allow some 20-30 years of development after 1890, it can be quite good. If you are handwaving a bit, you can add a planet or two that buzz in low frequency (Jupiter and Saturn actually do, so do some quazars, the Sun, etc, but you will need some later technology for that). This way you can have a constellation of radio sources to look for. [Answer] The only effective way of navigating is the good, old-fashioned surveying method. Set up a theodolite at a known marker with another known marker behind it. Send someone hiking ahead with a survey's pole to an unknown point. Measure the angle to the unknown point (horizontal and vertical, using the backsight line for the horizontal angle). Measure the distance to the unknown point (assorted ways of doing it, including simply stretching a line). Pack up the surveying gear, head on down to the guy with the pole, and mark that position. Send the guy with the pole off again, and while he's hiking, you set up, backsight, measure the angles to the new unknown position, rinse and repeat. After that, you'll have a whole bunch of triplets consisting of a horizontal angle, vertical angle, and distance. And now someone has to draw those on a map. Hooray! Now you can use them to calculate where you are horizontally and vertically, based on the place where you started, which is a known location. And you get to do it in the dark! [Answer] Sir John Ambrose Fleming invented the first thermionic valve or vacuum tube in 1890 and research into radio waves at higher energies got truly started. At first not surprisingly the quest was for distance and it was not long before researchers discovered that longer wavelengths could skip around the planet. However radio waves get quirky below a certain range and instead of bouncing off the ground, mountains and charged atmosphere layers will instead go straight through them more akin to magnetism. For over a century this was just a quirky footnote until the 1970's when a group a cavers got drunk with the electronics geeks and several designs for portable VLF (very low frequency) radios such as the Molephone, Ogophone & Troglaphone appeared. These devices would enable a surface team to track with a moderate accuracy the subterranean explorers & communicate with them. more info at <http://www.scavalon.be/avalonuk/technical/radio1.htm> [Answer] Looks like sound waves are the best bet. The governments/kingdoms could mantain a net of sound "Lighthouses" (beacons). Like a example the Egyptians had the Faros (one of the Seven Wonders of the (Ancient) World). Using different frequencies and time of release (sounding) for any of these sound beacons plus a really accurated clock could make navigation possible. But, more importante, it is a matter of mathematics. I think it is possible. Before GPS seamen could loud yell and wait the echo answer. By counting the heart beating they could to estimate how away was the sea shore. Hard to believe, but it is true. [Answer] Since there are known openings, people could measure location underground as a set of vectors from a know opening. For example, "Starting at BookTown, north 50m, east 25m, right at the fork, continue for 35m, etc." Also, Using this technique, common locations underground would evolve and the directions could change to something like this: "First, get to the BookTown underlibrary, then exit using the east corridor for 35m, right at the fork, continue 35m, etc." [Answer] Just my 10 cent to add to the others[[1](https://worldbuilding.stackexchange.com/a/171723)] answers... * Depth The Earth (and so your world) is heated by the Sun from the surface and by radioactivity from the core [[2](https://en.wikipedia.org/wiki/Geothermal_gradient)]. Close the surface it is affected by the surface local conditions, with a time delay depending on the depth. Deeper not. So a good thermometer may give you indication about the depth. Remember on the Earth the geothermal gradient is 25-30 degrees per km, but on your own world it can be different. Pressure may work well too. * Longitude is hard, but... the world spins always in the same direction. So is the propagation of the heat wave from the surface (a delay that depends from the depth). So enough close to the surface you may create to find special mushrooms, stones, vegetables with an orientation East-West... at least for the direction. ]
[Question] [ In my [other question](https://worldbuilding.stackexchange.com/questions/67281/what-off-earth-colony-would-be-easiest-to-build) I tried to find out if it makes any sense to colonize other planets or moons instead of just building space stations. The answer I accepted seems very well elaborated to me and confirmed my assumption that, with the technology and resources needed to build even a base on mars (far more on the moon or any other body), it would be easier to build a space station that could house the same amount of people in a controlled (and more paradise like?) environment. So assume we tried and did everything. We built bases and perhaps colonies where possible on every planet and moon of our solar system. And we also built space station colonies. Perhaps located in the asteroid belt where they built more and more stations from materials of the asteroids. Someday the whole asteroid belt would be converted to space habitats (like a poor man’s version of Larry Nivens ring world). This assumes that the asteroids give everything needed for this "self-replication". Now we discover a stable wormhole or other mechanism that gives us easy access to another solar system, similar to our own, except there is no earth (nearest to earth perhaps something like our mars). With all that technology, knowledge and experience at hand, what could be reasons to colonize the planets there (instead of just building scientific bases or perhaps some mines and space habitats for living in this system also). If I find no reasons I will colonize the galaxy in my story with space stations and ignore the planets or use them only for mining of things that couldn't be mined easier in asteroids. Until perhaps a perfect second earth is found. To make it clear "You can't find material XXX in asteroids and have to mine it on a planet" is just a reason to build a mine base with mass driver there. Not a reason to colonize any planet. Would the love of adventure (explore a planet, where no man has gone before) or stubbornness ("I want solid ground under my feet") of humans be enough to make them colonize planets under harsh conditions instead to live a simple life on a paradise space station? Or any other reason? [Answer] ## Planets are AWESOME My best guess is that people would only want to colonize planets if other solar systems if they have already successfully colonized planets in this solar system. If they've been floating around in the asteroid belt for long enough, they will have had the time to go ahead and [terraform Mars](https://en.wikipedia.org/wiki/Terraforming_of_Mars). If Mars has been terraformed, then they will have discovered that living on planets is AWESOME! 1. There's a beautiful wide open sky. 2. You can shove plants into the ground and they just GROW. 3. Clean water falls from the sky. 4. There's so much to discover and see in nature that just can't happen in a captive environment. ## The Crazy Gene So, if your humans have indeed terraformed Mars, and some of them live there...they might get the bright idea to try it on another planet in another solar system. Humans possess a gene, let's call it the crazy gene, that makes us want to venture out into the unknown and discover more. In [The Sixth Extinction by Elizabeth Colbert](https://en.wikipedia.org/wiki/The_Sixth_Extinction:_An_Unnatural_History), Colbert outlines that this gene is what set us apart from the rest of the prehistoric humans and led Homo Sapiens to conquer the Earth. ## Everyone wants to be in a history book Everyone wants to be the first person to discover/colonize/write about something. The tantalizing ability to be the first people to live on a new planet in a new solar system and go down in history is motivation enough to want to live on a new planet. Couple that with the fact that Mars already has been terraformed and its original settlers are revered as historical gods, and you'll get some volunteers right off to settle a new colony. ## SCIENCE Finally, think of the scientific possibilities. If you have a fleet of space stations, then you probably have a decent amount of humans and a decent amount of them are scientists. The reason that anyone goes to the space station right now is to perform experiments (most are zero-gravity experiments). Imagine the situation is reversed and there is the opportunity to live on a PLANET and perform experiments around the clock without the need for artificially simulated conditions. Many scientists would beg to go to a planet's surface and experiment with the atmosphere, magnetic fields, and gravity. They could even possibly discover a quicker method of terraforming. THAT genius would go down in history for sure. [Answer] Survival The reason we are already looking for other planets to live on. Is that our sun will die and we need to find another star system, if we want to exist longer than that. At the Moment the most interesting systems are the ones around so called "red dwarves", these red dwarves "burn" their fuel much slower and because of that have a far longer lifespan than normal stars. Look here: [In a nutshell: red dwarves](https://www.youtube.com/watch?v=LS-VPyLaJFM). About these red dwarves and the idea to colonize planets around them. [Answer] ## The Same Old Story The reason why people would colonize planets is for the same reason that cities grow up the way that they do. You start with a small outpost that does a certain thing (e.g mining for a resource). Once you have people living in that outpost and doing work, you now have a need for infrastructure to support them. Say you start with a nice little mining outpost. Whatever that resource is can't be found out in space, so a dedicated workforce is necessary to extract it and ship it out. So you have miners, engineers, stevedores, overseers, and probably a few other jobs. This base is already looking like it will have a staff of hundreds if not thousands. All of those people are going to need basic supplies like food and clothing, tools and replacement parts, and little luxuries like tobacco and alcohol (or their equivalents). Not to mention entertainment and things to spend their money and downtime on. Sure, some of that stuff can be brought in from off-world and to begin with most of it will be. But as the outpost gets settled and grows they are bound to find things that are easier or cheaper to build/farm/produce locally. Having an on-site forge means that you can manufacture replacement parts as needed without having to wait for a shipment of things, and in the spare time it can be used to create other items that can be used or sold by people. Eventually, industry is going to start popping up. Bars, restaurants, general stores, maybe a casino or theater or some other entertainment area. Each of those businesses is going to require more people, who will have their own needs, which will drive demand of different goods and services. People will get sick, so now you need a hospital. People will get into fights, so now you need a police force. Infrastructure will need to be built, so now you need more engineers and architects and people to manage the other people. None of this is going to be occurring in a romantic vacuum either. People are going to want to bring their families with them when they start this job, or will find someone to start a family with once they are there. With a bunch of kids running around you are going to need some kind of school system, and maybe even a dedicated daycare center to help take care of them. Between the industries that grow up to supply goods and services, and people starting families, eventually you are going to have a big enough population that new settlements could be founded. If there is some other resource nearby that would be useful to the original outpost, you could have people settle there and start up a satellite community that supports and trades with the main hub. Now the main outpost would bring in even more of some supplies, and would use those to trade with and support its own population and that of any other settlements. I wouldn't ask why you would colonize planets, I would ask how advanced your tech would have to be not to have some colonization. As far as I can see, the answer would have to be incredibly before any of the usual economic principles stop applying. [Answer] Some advantages to planetary colonization over space stations: 1. Resources Resources would be far easier to obtain on a planet. It would be far more efficient to build mining operations on a planet and send them across land than it would be to send spaceships to asteroids, set up mining colonies there, and ship back over distance. Also, the soil and rock on a planet, as well as any gases in the atmosphere could be used for various reasons including expansion and repairs. 2. Atmosphere The presence of an atmosphere would protect the colony against smaller meteors and other space debris. Also, the presence of an atmosphere could lend itself to eventually be converted to one suitable for human life. 3. Growth/Expansion Because a planet is a solid object, additional space for expansion could be dug out, whereas any expansion to a space station would have to be attached and done so externally while exposed to space. This would be much riskier, and the lack of gravity would make for additional concerns, and make rescue operations much more difficult than on a planet 4. Survival A planet would allow for multiple bases, spread out, more redundancy, and less risk of total annihilation of all concerned. As our own solar system will eventually die, establishing planetary bases would be essential to ensure our survival. 5. Maintainability As with expansion (above) it's far easier to simply walk outside to fix/maintain/expand a facility than it is to risk a space walk in weightlessness. 6. Magnetosphere This is more of a concern than you may realize, because combined with an atmosphere, this would protect the colonies from radiation, thus requiring less shielding on the planet. [Answer] # Space is dangerous A space station is basically a really, really tiny planet. So imagine you lived on an asteroid big enough to house a few thousand people. What would you need to survive? What would you do if something went wrong? Now, compare that to what would happen if you lived on an earth-sized planet and something went wrong. # Flying rocks One of the biggest dangers in space is flying rocks. A tiny one can put a good sized hole in just about anything you can manufacture. Most machines that humans build don't work well with holes added to them willy-nilly. A space habitat needs passive or active micrometeorite defenses. If the active system fails, it's only a matter of time before the passive system (i.e., really thick hull) fails and you have a Very Bad Day(TM). A planet, on the other hand, only needs a passive defense, and it's pretty much always available: it's called "an atmosphere". If you lose that, you've screwed up something really big, and you have other problems to worry about. # Cosmic rays Radiation is everywhere. If you're close to a star, the solar wind will bombard you with all kinds of high-energy particles that you really don't want going through your body. Again, you can have an active defense like a magnetic shield, or passive defense like a massive lead hull (very expensive). A habitable planet has two excellent passive defenses: that good ol' atmosphere, and a magnetosphere (well, not all planets have one, but you should modify it if it doesn't). # Ecosystem A space hab must have a closed ecosystem. But the stability of an ecosystem is a function of its size. Trying to make a closed ecosystem on the ISS would be insane, and probably impossible. Even if it worked, it would undoubtedly operate on a razor-thin margin. A giant hab with thousands of people would be better, but if some disease started ripping through your food supply, how long would the inhabitants last? What if resupply ships were too far away? Very easy to make the Donner Pass in Space. An ecosystem covering millions of square miles will be thousands of times more stable than even a very large space hab. It would be able to host far more diversity in the food chain than is necessary to have a reliable supply. A space hab might be able to grow enough food to feed humans, but it is unlikely that it could grow an enjoyable diversity of food. The space available on even a small planet would explode the farming/animal husbandry options. # Manufacturing How do you get new goods on a space hab? You can recycle, you can mine nearby asteroids, or you can import raw or manufactured goods from planets. If there is any kind of disruption in the flow of materials or goods, the space hab could be crippled for new manufacturing (if it even has a meaningful manufacturing capability). This is especially relevant for warfare. Imagine trying to build fleet from space habs. If I were your enemy, I would know that all I need to do is disrupt your supply lines, and thereby cut off your ship-building capability entirely. I could destroy your navy before it is even built! A planet can not only provide the raw materials for a space navy, it can provide a secure staging area for defensive weapons if you choose to attack my shipyards. I can build massive power generators in remote parts of my planet without putting my population at risk. If you build powerful generators near your space hab, they either need to be close enough to endanger your population, or far enough that I can attack them without dealing with your hab defenses. That limits the kinds of defensive weapons you can field. # Defense In the event of a full-scale war, I would much rather use the natural deterrents of atmosphere and land to provide shelter than having to build every last shield in space. If my population relies on transported raw materials, my supply lines are a constant vulnerability. You could attack continuously, wearing down whatever defenses I have, until I run out of materials to rebuild. You have your choice of beam weapons, missiles, and kinetic kill vehicles to attack my space hab, which is presumably not very mobile, making it a sitting duck. And because volume is expensive in space (and makes me even more vulnerable), my people are crammed into a small area that is extremely trivial to target. Having to defend a space hab is a terrible military position. On a planet, I can disperse my population, making any concentrated attack a waste of resources. I can tunnel underground, forcing you to either waste energy blasting through the surface, or landing for an invasion. Beam weapons will be attenuated by the atmosphere/magnetosphere for certain frequencies and beam types. Missiles will have to contend with potential counter-measures from all over the planet's surface, or in any number of orbits. Kinetic bombardment is made more favorable by the planet's gravity well, and may be the best attack. But if you can launch something big enough to kill my planet, then you can surely blow up any space hab you like with the same rock. If you are forced to invade, then I will have the advantage of native soil. # Conclusion If I'm the leader of a space-faring civilization, I will choose to colonize planets over space habs every day of the week and twice on Sundays. I would only build habs in remote strategic locations where I want a presence but no suitable rock exists. Habs might be a nice vacation spot if you want exotic properties (controllable gravity, day/night, etc.), but not a sound basis for a large civilization. It is risky, costly, and foolish. [Answer] To get away from idiots. What is holding people up from creating that perfect society? You know, the one where kids can walk to school unescorted and nobody has locks on their doors because it is inconceivable that anyone would open somebody else's door uninvited? Idiots. Antisocial jerks who just don't want to play along with your society. You can try to build your Utopia on Earth, but most of the good places are taken and filled up with idiots and jerks. Let's face it, most of the human population are idiots and jerks who need years of training and conditioning just to tie their own shoes, and all of that socialization still doesn't prevent them from taking your stuff if it isn't nailed down or chained to something really big. Having to nail your stuff down or chain it to large objects is super inconvenient. So if you want to make a society on Earth that doesn't suck, you have to do something about all of those idiots and jerks. The most common approaches, such as relocating them to some other place with a suitable habitat or turning them into fertilizer, have distinct drawbacks. That leaves relocating yourself and like-minded associates to some other place that is hard to get to. The "hard to get to" part is pretty important, as the idiots will definitely follow you if you're just going across the street. There might be other considerations when planning your colony, but the "better society" angle will be hard to overlook after the first colony is established. Consider: Transport to your colony will be difficult and expensive, and the number of slots for colonists will be limited, so when interviewing for those slots you will be focusing on getting only the best and brightest. In other words, the colony will be built from only the smartest and most capable individuals that humanity has to offer. Idiots need not apply. The society such people could build would be enviable, which is why the idiots would want to get there. To the idiot's way of thinking, "Wouldn't it be great to live in a place where nobody ever locked their bikes? I could steal bikes whenever I wanted to!" [Answer] Humans are a parasitic species and are driven to expand and consume available resources. At no point in human history did anyone ever refrain from colonizing a new, resource rich area. Although we might eventually have the technology to form a self sustaining, enclosed ecosystem and stop the expansion and pillaging of nature, right now we do not have that tech, and maybe it is not an achievable goal. Perhaps expansion and growth is a requirement for life itself, since we don't know of any counter examples. Either way, i think its safe to say that humans will colonize th other side of the wormhole, simply because they can. Furthermore, MONEY. It is safer, easier and cheaper to do many things on the surface of planets. Small mining colonies will appear around resource mining sites, providing support and entertainment and tangental services for the mining work. It'll be too expensive to ship hookers down from orbit every saturday night, so local brothels and liquor stores will open, local food, local tool repair, clothing, etc and this will slowly grow to towns and small cities. If planets with organic chemistry are found then that will be a lucrative natural resource which is very rare in the asteroids. Complex hydrocarbons, algae, plants and possibly even animals provide a wealth of complicated compounds and molecules not easily produced off-world. It would be natural for farms and trading posts to form around these. Even without organic chemistry, planets with atmospheres can provide more interesting chemistry than sterile, static asteroids. [Answer] People in general prefer familiar environments, so much so that if you look carefully at modern inhabited landscapes, the humans have essentially recreated the open African Savanah environment that Genus Homo evolved in over 5 million years ago. Planets will have arbitrary gravities, atmospheres, radiation environments and day/night cycles. With some super science, lots of energy and time it is possible to move planets around and change their rotational periods. British researcher [Paul Birch](http://www.orionsarm.com/fm_store/Paul%20Birch%27s%20Page.htm) wrote several papers on terraforming and moving both Mars and Venus, so if we can conceptualize this now, then it should be doable in the far future. Of course the real issue is "efficiency", or in economic terms "opportunity costs". For the same amount of time and expenditure of energy, you could build and operate millions of free flying colonies in space, and each one would be designed by default to rotate to provide 1 "g" and have a 24 hr day/night cycle. For most people, the near term payoff would be much more attractive than setting up solar windmills and high speed pellet streams and all the other associated technology needed to move planets around, and then still having to wait decades for the planet to get into the right position. (There is the other issue that the planet itself might be destabilized from the move, so you need to wait additional time for the earthquakes to end before you can even start terraforming!). So especially after a long term space civilization has been in existence, and people are used to building their environments to suit, they may look own planets as raw resources to be mined and shot into space by robot workers, while the people bask in the filtered sunlight by a beach made to order. [Answer] ## Radiation Planets have large amounts of mass and, frequently, a magnetosphere, which will shield colonists from solar radiation. In the case of inert lumps of rock, like Mars or Luna, the body of the planet(-oid) will provide shielding for half of the solar day. On a planet with an active core, like Earth, the shielding is effective all of the time. In a space station outside of a planetary magnetosphere there is little to no shielding against X-rays, hard X-rays, or gamma radiation. Your colonists in space habitats will have extremely high rates of cancer and birth defects. [Answer] Cost You're right, building a space station is cheaper - for the first couple hundred thousand people. By the time you get to a couple million people, your infrastructure costs are going to be enormous. All that free land, free water, free gravity, free air, free recycling, etc. is going to start looking pretty good. When you have a billion people, will space stations even be an option? [Answer] Another reason to colonize a planet would be because humans evolved in one. We don't know about the psychological consequences of being raised without temperature changes, not to be exposed to air, dirt, different water pressures, nature or just to see the horizon or the sea. Besides It would be difficult for somebody being raised on earth to adapt to living in a space station for the rest of their lives. I think the best bet for humanity's survival would be to find an earth-like planet. [Answer] Survival of the species, our biological prime directive. If we can build sufficient number of self-sustained (with space mining etc) space habitats, we are in no particular hurry. However, if technological capability collapses for any reason, space habitats become space graves very rapidly. The chain from raw asteroud material spread over interplanetary distances to humans successfully maintaining their population in space is a long chain with a lot of very fragile links. So, we need planets, terraformed planets in other solar systems, and we need to populate them with self-sustaining colonies which will survive even if access to space disappear, even if advanced infrastructure is destroyed. So, answer to your question: we want to not just colonize but fully terraform other planets to increase the odds of our species surviving. Now you need to come up with reason for us to want to survive so much, that we are willing to pour resources into planetary colonization. Perhaps a close call, like computer or biological virus outbreak which is barely stopped, or a very close call of a comet destroying the Earth, created the will to do this, or maybe it is a religion or philosophy, which advocates this and has enough followers to also fund it. Many possible reasons, worth of its own question (if it hasn't been asked before). [Answer] The reason to do this is the expansion. The expansions of the Humanity. The reason to do anything in the space is the expansion. It is not a bad thing - there is nobody (known) there from which we would conquer land, planets or any resources. They are free. Ethical problems would exist only if they had already owners. [Answer] I don't think we would colonize many planets once we were capable of building space habitats of sufficent quality Although space habitats require an enourmous amount of time and energy, planets do too. * The gravity well of a planet means that it takes an incredible amount of enegry to get on & off the thing. Space habitats don't need to be landed on, only docked with. * Almost all planets will need to be terraformed (assuming that you don't want to live in an enclosed colony on the surface) so, after finding a new planet, you need to seed it and wait thousands of years. The only reason I can think of to keep using planets is that people "just like them". Maybe that means they just visit them, or maybe they colonise them if they permanently move to another solar system? This is pretty thin though, so I reckon that there will come a point when humanity's response to whether to colonise a planet or stay on their ship would be "Why bother?". [Answer] A big reason not mentioned so far is the idea of factions and territory. For example, England, France, Spain, and Portugal rapidly settled North America in attempts to be the territorial rulers of the landmass. From this they often gain exclusive resources as well as general support. You mentioned that they would just want to mine with a mining station, however it's often the case that a large community builds up around an industry. Sometimes the community will move when the resource runs out, but often they will not. California still has a huge population, even though few people there mine gold any more. In addition to the faction getting these resources, they also control a larger area of space. This can be useful for tactical reasons ( re-stocking military ships, trading ), as well as overall notoriety. Big contracts other places go the factions/groups with the biggest support base and resources. Colonies can get this, while simply mining operations cannot. [Answer] One word: MAINTAINANCE. Space stations require multiple systems for maintaining life support resources - air, water, food, waste-disposal, general cleaning, etc. - and all of these systems require constant vigilance to prevent catastrophic failure. Do YOU trust humans to sustain that level of diligence over generations? - 'cause I don't. On the other hand, for a planet, once you establish a robust ecology, it is AMAZING how badly people can treat it, yet it still supports their existence [e.g look at Earth. Now.] [Answer] First of all I would like to correct a few of you. Only OUR star system is called the 'solar system' as only our star is called 'solar'. Therefore the term you should use 'star system'. Now onto the question at hand, the sheer cost of producing an artificial sustainable habitat in space would be phenomenal, we're talking 10s of billions. They are also far less attractive unless of course you create a completely synthetic eco-system. Planets have the benefit of being FREE and completely expendable. They have a vast amount of easy to obtain resources and if you're talking about Sci-Fi then perhaps their atmosphere can be terraformed? Also they are much more beautiful and spacious, whilst a space station is confined and isolated. Planets over all are far more convenient. New scientific discoveries and break throughs can not be accomplished if you are isolated in space. However researching other planets, air compositions, biology etc.. Also I would like the fact that the sun still has roughly 4 billion years left and humans will likely not have to worry about the consequences of a giant swallowing the Earth. I hope this helps. [Answer] At its core, this can be answered with a simple economic calculation in the form of a cost-benefit analysis (CBA), but the outcomes will vary greatly on information we collect, probably in the future, about the real costs of choosing one approach over the other. First, enumerate the number of possible environments in which humans might prefer to spend the majority of their lives in a way that is pleasing to them, i.e. space stations, domes, tunnels, ring worlds, terraformed surface colonies, etc. Then ask, would a large enough amount of people prefer to live in an environment similar to that of Earth such that the economic incentives for firms or governments would actually be aligned with a terraforming orientation? Or would it be the case that people, when confronted with the real costs of the entire affair, simply don't care as much as they might have once thought and so resign to living within artificial structures such as space stations or protected surface or sub-surface structures such as domes or tunnels? 1) Is the cost of terraforming a planet in such a way that humans can live natural lives in a way that is similar to that of their memory of living on Earth (or conducive to their natural predisposition for Earth-like environments) greater than the benefit otherwise accrued? 2) Or, perhaps more related to the OP's main question, is the cost of building artificial structures on otherwise environmentally hostile extra-Earth planets greater than than the benefit otherwise accrued? This question will likely depend on the supply of livable space and the time horizon of our desperation. If our sun is very close to dying, then yes it would probably be both cheaper and less risk-averse to set up space stations in stable orbits around massive structures that produce substantial gravity, i.e. planets or moons. If it turns out that we develop the technology to live as we do on Earth on other planets vastly prior to any kind of calamitous species-threatening event, then we may or may not choose to terraform planets to live on their surfaces depending on the array of alternatives available to us. If full-dive virtual reality (in which our conscious experiences can be totally overridden by programmatic environments) is invented before our space-faring age proper, then the actual physical cost of living will become so low, i.e. measured in single Watts of electrical energy. It is probably more likely then that we would prioritize our space colonization efforts in a way that minimizes cost as a function of the amount of space required to fit a sack of human flesh snugly into a pod sufficient for generating a pleasurable conscious experience for an entire lifetime in virtual reality. The thinking goes, "Well, since the sun is about to blow up, or since VR life is so much better than RL life and given that it's also incredibly cheap, let's just find room for a bunch of servers and some sleeping pods so we can at least live full VR lives in space rather than risk our species existence altogether, or rather than exerting all that effort to build worlds that we can just simulate anyway." If it turns out that for whatever reason people never adapt to living full-dive Matrix-type lives then the question would come down to the environmental conditions and possible hostile negative affects of living either in orbit or beneath an alien atmosphere (if there is one?). And again, this will come down to technology. Can we properly deflect UV radiation in space with some kind of shield for long periods of time without experiencing technical shortages? If this technology is never mastered, then we might kill two birds with one stone by terraforming a planet, allowing us to live Earth-like or similar lives while protecting ourselves from the dangers of radiation in space. In conclusion, think about the technologies your world possesses and how expensive or possible each one is and how this would impact the thinking of the agents and institutions involved in making these decisions, whether it be colonizing planets or setting up server farms for VR-possessed human beings. ]
[Question] [ If you were to hook up a human being to a sort of syringe sized water wheel to generate power using the force of their blood flow; how much power could they generate? Consider a human in a medically induced coma on a steady drip of some kind of stimulant like adrenaline to speed up their heart rate and blood flow. Would this produce more power if the physical condition of the person didn't matter like permanent organ damage as a result of the process? [Answer] Nope. Not very useful in the way you proposed. Just imagine using a tank on a treadmill as a battery to fuel a ship: you'll lose a lot of power, unless you have a zero-cost source of tanks and fuel for them. Any animal (including a human) needs a power for his systems to be alive and running, so making a living organism into battery by using one of his organs (blood flow / muscle power / etc) is very ineffective, because a lot of energy is spent supporting all of the co-operating systems, UNLESS you have cheap means of producing fuel for his "reactor" - like some magical device, that can produce food from nothing, OR (e.g.) you belong to a race of aliens, that consumes photons and defecates proteins, fats and carbohydrates. P.S.: There actually is in human history an example of "food producing magical device", used to power working horses/bulls/donkeys - it's called "earth". Basically fuel for these animals (grass) grows by itself and in some cases (summer-autumn) the human has to spend nearly zero energy to power these animals: just walking them throughout a field works fine - they eat the grass by themselves. [Answer] [This](https://talkingphysics.wordpress.com/2012/03/07/work-done-by-the-human-heart/) dude estimates the work done by the human heart as 0.5 J/beat. Assuming a resting heart rate of 60 beats / min, that gives us 0.5W of power, or 43.2 kJ per day. Assuming a 115 lb person sleeping [burns](https://www.healthstatus.com/health_blog/body-fat-percentage-calculation/burning-calories-sleeping/) 42 Calories (which are kilocalories) / hour, that means you need to ingest about 1008 kilocalories a day to be an unconscious blood pump, or 4.2 MJ. So you are getting an energy efficiency of about 1% converting food energy to mechanical energy. Considering a steam engine gets about 10% thermal efficiency, you'd get 10x more mechanical energy burning the food you would feed this person in a steam engine, instead. Even if you developed some mechanism for speeding up the heart, you would still have to increase the amount you fed this person, and the efficiency wouldn't change much, if at all. [Answer] I long ago designed exercise bike controllers. Figures below are from memory and 'less than exact' but should give ballpark ideas. Use a (conceptual) bike! Rather than trying to harness blood flow and heart-pump which are not optimised for energy output, use a portion of the body which is - ie leg muscles with suitable electrical control signals for leg activation driving an alternator or equivalent. The "user" could be in any suitable position - on their back with legs bent to drive pedal mechanism would work well enough (bicycle position rotated backwards about 120 degrees. Or a "recumbent" posture. Many ideas [here](https://www.google.co.nz/search?q=recumbent&num=100&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwisxeX43MjPAhVBtJQKHaIkD40Q_AUICCgB&biw=1745&bih=973). Various ideas of how maximal energy can be extracted over longer periods. Note attitude of rear rider in tandem configuration. [![enter image description here](https://i.stack.imgur.com/Kt7HV.jpg)](https://i.stack.imgur.com/Kt7HV.jpg) Available energy: Start with an energy input of about 2000 kilo calories per day for a semi sedentary person. 1 cal ~= 4.2 watt-second = 4.2 Joule. 2000 kCal = 2000 x 1000 x 4.2 J ~= 8.4 MJ/day. 1 kWh = 1000 W x 3600 seconds = 3.6 MJ. So TOTAL food energy for average person ~~~= 2.333 kWh . At (unobtainable) 100% efficiency that's about $0.60 of electricity at 25c/unit. If you can extract 10% of total energy from user that's ~=1/4 kWh or 6c of electricity equivalent./day. More food = more energy and probably a greater % out but still small. Sanity check: I could pedal an exercycle for say 15 hours/day at 50 Watts if my life depended on it. 50 Watts is a very easy pedalling rate against a light but noticeable load. After an hour os so I'd find it annoying (some wouldn't). After 15 hours I'd be exhausted but it should be maintainable given enough food and fitness. That's 50W x 15 hours x 3600 sec/hour = 2.7 MJ. My food requirement would rise - I'd expect to 3000-4000 kCal/day or say 12-16 Mj/day range. I could maybe do 100 Watts for an hour and be "rather tired". Once I could do 500 Watts for about 10 seconds and then needed a good lie down :-). To fly the English Channel under your own power takes 300-500 Watts for as long as it takes. That makes the mechanical output about say 15-20% efficient. Not bad. On the level on a bicycle I'd expect 50 Watts continuous to give me say 4 to 5 kilometres per hour so that would take me about 60 to 75 km in a day :-) Any hills would greatly reduce that. Leg muscles, heart etc could probably be run semi indefinitely (given enough food input and suitable plumbing) at say 100 Watts, so about triple my 100 Watts x 15 hours results. Energy sources: Despite what people say here, I've long been impressed at how much work you can get from a human body on a kg or so of semi random carbohydrates. If you used solar heated ponds to grow "[\\ Cyano-bacteria aka blue- green algae aka 'pond scum"\\](https://en.wikipedia.org/wiki/Cyanobacteria) you may [tm] be able to run the energy production system on the output. Each person-unit is only running at 100 Watts say but 24 hours / day so that's equivalent to eg a solar panel's 4hrs mean sun/day year round in most areas. So a 100W person gives the same daily energy as a 600 Watt PV panel which has an area of about 4 square meters at current module delivered efficiencies of say 15%. A panel does not need algal fuel - but a person unit can probably fit in one square meter and can be stacked N high, unlike panels which must "see" the sun directly. Persons have to be plumbed (algal matter and water in, waste products out). The algal ponds take extra area - probably in excess of the PV panel area needs. Overall it may depend on available resources - but PV panels sound like an easier task :-). [Answer] That’s an interesting question. Unfortunately, there’s no exact way to perfectly describe the energy output of your imaginary blood-dam, but this equation easily suffices: \begin{equation} P=(\eta Q \rho v^2)/2 \end{equation} Where P is the power generated, η is the efficiency of the dam, ρ is the density of the fluid in kilograms per meters cubed, Q is the volume flow rate, and v is the velocity of the fluid in meters per second. The average density of blood is approximately 1060 grams per meter cubed, and we'll go ahead and assume that your blood-dam is 100% efficient for simplicity. Since we want to maximize your energy output, we’ll draw from the biggest vessels in the human body, which clock in with a blood flow of .4 meters per second and a volume of .0004 meters cubed per second. Crunching all these numbers, you get about 33 milliwatts. Needless to say, this isn’t very much. This could power, say, a laser pointer, or a hearing aid. If you gave the person a stimulate like you're suggesting, you still wouldn't be able to break one tenth of a single watt. Honestly, you’d be better off just burning the body and harvesting its bioenergy. [Answer] Incredibly little. Likely a net power drain when you consider the power required to maintain the set-up. You could get more net power by just hanging a bag of water and putting your "syringe-sized water wheel" on its outflow. Even this would not give you a positive energy source, as you would have to use energy to refill the bag when it runs dry. [Answer] It's not very effective. If you think for a moment about what an organism does and what it consists of, you'll notice that it has a large variety of organs that help it to function in various ways. You have a heart to pump blood, you have a whole system to convert food for energy(and other useful things). You have a brain (he's the killer, uses muuuuuch energy). The list goes on and on. You also have to maintain the proper temperature, stuff like that. Now imagine a simple pump. It has a... pump. Maybe some engine, some things to make it work better. You don't need to do anything like maintaining temperature, digesting, getting rid of the waste or powering the organs you don't need. Human can also be bigger and harder to maintain(and maybe even replace) then a mechanical pump. So no, you don't use humans for such things. Look at how we use animals; nowadays it's mostly for food. However, since we are now getting further in technological advance, and we are able to grow meat in the laboratory, soon(probably less than a hundred years or so) we won't need them for that, as we will be able to create the meat much cheaper - we won't need to clean, grow, feed and care for the animals and we won't need cages and place for them to live; we will simply grow meat, the only thing we want. So yeah, unless machines want to use our brain for thinking hoping for some clever ideas or just like our meat and can't get it any other way, we're mostly useless. [Answer] What about heat energy? I don't have good source at hand right now, but I've heard several times that the body generates about 100W od heat energy. Now you only need some good device to transfer that to electricity. You could try something like Peltier generator or some other [Thermoelectric generator](https://en.wikipedia.org/wiki/Thermoelectric_generator). Trouble is that the efficiency is (according the wiki article) 5–8% But maybe that can be improved. And of course you still need to feed that body... You can also combine this solution with the others. ]
[Question] [ I‚Äôm writing a low magic fantasy story in which there‚Äôs a race of creatures called shadow-thralls that were basically bred as a slave race by a wizard thousands of years in the past. In the present day,they‚Äôve somewhat assimilated into human cities after being liberated, however they instinctively turn to pillaging and raiding if not kept busy. They are weaker and less intelligent than humans. For story purposes, shadow-thralls periodically revolt and begin raiding every few decades until they‚Äôre brought back under control and given something to keep them busy. My issue is that I can‚Äôt really think of why a medieval society wouldn‚Äôt just exterminate them. I need them co-existing with humans for plot reasons, but I also recognize that humans would likely have turned to extermination within the first few uprisings, kind of like how Europeans almost drove wolves extinct or how homo sapiens killed off the Neanderthals. Basically I‚Äôm asking what would motivate humans to tolerate a genuinely an aggressive race of ‚Äúevil‚Äù weaker beings and not just genocide them? [Answer] Prisoners Dilemma -- They make VERY good slaves. When we defeated Dire ArchWizard ScaryBad 200 years ago, we took all his gold and treasure. We also took his Shadow thralls. They were created as a slave race. They are still a slave race. Only now we crack the whip. Our standing army is mostly Shadow thralls. Even though they are physically small and weak [they make good footsoldiers because they were designed to fight and to follow orders.](https://worldbuilding.stackexchange.com/questions/222275/creating-a-species-purely-for-warfare/222292#222292) So a formation of shadow trolls does not break as easily as a formation of people. Even after it breaks they continue fighting. Our neighbours' have similar armies. Warfare is mostly thrall on thrall. No one wants to be the first to drop their thrall army and revert to human soldiers. That would take too long and leave you vulnerable. Keeping the army busy is not too too different from keeping a regular army busy. In Ancient Rome inventing jobs for the generals, to prevent them seizing power, was one of the Emperor's main jobs. The thralls spend most of their time drilling and training and the rest on large public works. They build fortification and pyramids. They dig cesspools and moats. Sometimes we have a second band follow behind and fill in the moat behind them. This keeps two battalions busy rather than one. They take well to this regimented and busy lifestyle. Thralls are only allowed inside a town's walls when doing construction. This is where non military people encounter them. The thralls are kept on a tight leash but occasionally one slips out and runs amok. Exception: Since thralls were originally a slave race of Dire ArchWizard ScaryBad, it is possible for other mages to bind themselves to one or more thralls. This lets the wizard mentally dominate their thralls at range. These thralls are not dangerous unless the spell is interrupted. They are branded with the Wizards initials and allowed to enter the town during daylight hours. The public is educated with a few tips to deal with an escaped thrall. For example if a shadow thrall enters your house remember to RWAG R: Retreat into another room or outside the house if there is no obstruction. Otherwise move into a corner. Ideally the opposite corner to the nicest, shiniest thing in the room. W: Wait until the thrall steals something with both hands. Thralls prioritise stealing booty over attacking people. A: Approach the thrall when its hands are full. G: Grab the thrall's left earlobe like Misty and Brock from Pok√©mon [![enter image description here](https://i.stack.imgur.com/4v6cA.gif)](https://i.stack.imgur.com/4v6cA.gif) When you do this, thralls are programmed to submit to you. They will carefully put down whatever they stole and roll over onto their back on the ground. They also release a pheremone that calms down other nearby thralls. At this point you are legally entitled to euthanise the thrall and the owner has to pay a fine for letting it escape. Or you can choose to bring the thrall back to its owner, and they have to pay the fine to you instead. [Answer] They have tried and failed already. Once in a while the humans decide that enough is enough and try to finish the job after putting down a rebellion. But it always fails for many reasons: * you have to convince all kingdoms to be fully 100% willing to complete this gargantuan task. If even one tiny city-state decides to not cooperate (secretly or not) you have already failed. * the extermination is too costly, at some point the soldiers simply cant be paid enough to keep them hunting for the length of time it takes to kill every last one. * total extermination is a brutal affair, and before it is complete most soldiers desert or ask for different assignments. * the thralls live in many, many places including in the wilderniss without humans. Finding them all and keeping the bloodlust high enough for years on end is just not feasible enough. * "what THESE thralls? No these are peaceful hard workers from our village that didnt join the rebellion". As you murder innocent (?) Thralls in more and more villages and cities the population that did care about them starts to rebel against having "their" thralls killed, possibly asking compensation as well. * pure greed. Enough people who employ them for cheap labor will want to keep them. "Here you go soldiers, all my Thrall work force wink wink money exchange. Execute them over there and dont mention the actual number of thralls I used to have". You can even make the once-a-generation culling of all Thralls a big thing in your story. People can agree or disagree, cultures could treat Thralls better or worse and even have deliberate cullings to keep the population down against rebellions (which causes the Thralls to rebel even with fewer numbers and makes that culture feel justified). [Answer] #### They do commit genocide at a regular basis. Most kingdoms have orders to kill them on sight. However, shadow thralls were designed to be expendable minions. Any decent evil overlord would never allow himself to either not kill their minions and not run out of minions to torture and kill out of boredom. Shadow thralls were engineered to reproduce at breakneck speeds when they are in low numbers. A switch stops this fast reproduction when they have "enough". This trigger is not understood, but it has to do with how crowded their warrens are and how easy it is to obtain food. Contrary to what one would expect, it is when food is harder to find that they breed the fastest, in order to have enough manpower to gather more food. Also, crowded warrens split, with a band of shadow-thralls migrating somewhere else. This was encoded in them by the evil overlord so they would expand the mining operation on their own. So, the shadow-thralls cannot be exterminated, no matter how much effort the kings are willing to spare. Somewhere in the wilderness, a warren will grow, divide, grow, divide, then reach back to civilization. Exterminating them is a gruesome job that's only done to keep their population in check. They have as much luck wiping the shadow-thralls than killing all the rats and roaches in their cities. [Answer] # You underestimate the economics of slavery "Why wouldn't they just exterminate them?" assumes that them being dangerous isn't true of human slaves either, and we've done slavery thousands of times. Slaves have always been a dangerous gambit, revolts happen, slave masters get killed in their sleep, they require constant policing to stop escapes. But economically speaking, slaves are basically guaranteed to make you rich, all this society would have to say to itself is "would you rather grow your own food and build your own houses?" "Would you rather be as poor as the next town over?" And if, as you're saying, they don't even really need policing as long as they've got something to do, then the cost/benefit decision is obvious. They don't even need to be particularly good slaves, cult leaders have gotten rich just by having their members doing minimum wage labour making novelty pens, as long as you don't have to pay people beyond building them a house and feeding them, things they would do with a larger portion of the money you would've paid them anyway, you keep the difference and can sell product cheaper than any competition. and your town can perfectly mentally justify this slavery because, as you mentioned, they get restless unless you give them something to do, so they see themselves as parents to a child race. Honestly slave races are a kind of offensive idea for obvious reasons, but if they're going to exist, you've pretty much already made an ideal one, it doesn't need more justification then you've already given it, people might be worried about the occasional revolts and violence, but that's true of real slaves, the culture will simply adjust and build structures for maintaining the status quo. [Answer] 1:Greed, As you said they are less intelligent then humans... so cheap labor could be a reason why the upper class (who is relatively safe due to personal protection) could use them as a labor force, so what if they kill a few customers here and there? 2: Display of power, a (religious) group could want to keep them alive and revolting to make the people scared so that they themselves can remove that fear by having a standing (holy) army to fight them if needed...of course this army needs to be funded so say hello to taxes. 3: Culture/Religion, their main religion might highly frown upon killing innocents, people have done stupider things in real life based on their faiths. 4: High reproduction, they might breed so fast that taking them out permanently requires more effort then it's worth (perhaps due to internal conflicts between the parties that have to unite to actually exterminate them. As you said they ere bread for war so a high reproduction number in a short time is something the wizard might have planned for. [Answer] ### Farming Your mistake in the question was the word "cities". The medieval world didn't have cities, not at the scale we'd understand today, and people didn't go there to assimilate. Medieval cities were only large towns, really, and not many people lived there. For the other 99% of the population, farming was the thing. And this is where the shadow thralls come in, because there is no such thing as a medieval farming economy with too much workforce. The more hands you have (in the absence of machinery), the better you can farm. You don't even need to develop the horse collar, because you have teams of thralls who'll pull the ploughs. You basically have the perfect slave economy, because unlike slaves they're unable to think about rebelling. ### Roads and other public works In the meantime too, the king and his lords also have thralls. When they aren't fighting someone, they can be solving the biggest problem for the medieval world, which was how to get soldiers around quickly. That's why all major roads in all medieval states existed. Thralls would be perfect for the grunt work of roadbuilding and maintenance. And then of course the country gets the economic benefits of traders also having roads to get goods around. Or city defenses. It took years to build defensive walls, and it took people out of farming to do it. With a strong farming economy, you've got plenty of food left for the local lord to put a team of thralls on that. In a medieval context, you simply can't overstate the degree to which the available man-hours of muscle was the limiting factor for development. If you've got extra muscle, it'd absolutely get used. No doubt some states would go down the "slaughter" route instead though - and they'll be crushed economically (and probably also militarily) in pretty short order. [Answer] Have you ever heard on the NYMB (Not in my backyard) syndrome? It's what happens when we want something, just not close to us. Like we want industries, but not close to where we live. Same here: a genuinely and aggressive race of ‚Äúevil‚Äù weaker beings is a good thing when it's busy in an enemy land, it's a bad thing when it's in our land. So, war is the reason why such creatures are not driven to extinction: they are too useful in war to be taken permanently care of. [Answer] Unique value Sounds very interesting! So, they're created as a slave race. Perhaps they have unique skills that make them invaluable. I don't love cats. Not as pets. I find wild cats interesting. But generally speaking, I don't want cats anywhere near my house or slaying local biodiversity: baby birds, mammals and all these other wonderful creatures I prefer to cats. However, I lived for a while in my mum's renovated shed, plagued by mice. I had no food in my shed or any traces of it and there was nothing I could do to keep them out. I could set traps and kill a few of them, but there was an inexhaustible supply of the little buggers and they kept me awake, shat everywhere and occasionally I'd wake up with one climbing over me. I soon moved into a bedroom in an old house with holes between the floorboards and hundreds of wonderful places for mice to live and eat and survive. Except that the house had three cats and in my entire time there I never saw the traces of a mouse. So yes while I don't love cats, I prefer them to a mouse infestation. I was pretty unhappy when one of the cats pissed in my room once. But overall I preferred cohabitation with these cats than with the mice. What I'm suggesting is that while shadow-thralls may be less intelligent than humans, they might be better at something than humans. I'm smarter than cats are, but I can neither hunt mice or deter them from inhabiting my abode. I would keep cats around sooner than let my home be overrun by mice. Maybe shadow-thralls are a form of pest control. [Answer] Politics: It's convenient for the leaders to have a periodic, predictable, easily handled threat that seemingly threatens society but is otherwise a useful workforce the rest of the time. It helps maintain those in power and promote cohesion. Also, everyone loves cheap labour. [Answer] Elephants My first thought was "elephants". In some countries, they are simply pests -- like having gigantic deer that eat human crops, encroach on human lands, are a danger to humans and livestock and were well on the way to being killed off. What stopped the genocide of elephants? They became a cash crop, mainly from hunters willing to pay extraordinary fees. By carefully selecting what the hunters can hunt, and where, and how frequently, the nations that have these elephants have turned them from a pest to a source of income powerful enough to convince them to expand elephant reservations beyond the original conservation agreements, willfully pushing back people to make room for more elephants. The takeaway is you just need them to be useful (and manageable) in such a way that despite the problems of them being pests to society, their value is too high to get rid of them. Maybe, for example, there is a tax on shadow-thrall ownership which goes into a "shadow-thrall management" fund which keeps things pretty well in check. People gladly pay the tax because the thralls always pay for themselves several times over. If things start to get out of control, there's already a crack team of full time Rangers whose only job (paid for by the taxes) is to deal with it, so the general population is rarely bothered. [Answer] Just tossing in a reference to The Mote in God's Eye, by Niven and Pournelle. In that case, rather than eliminate a very dangerous alien species, they set up a blockade of the planet. (Possible because their means of FTL had only one egress point from the system). [Answer] ## Ethics. Even on Earth, genocide tends to be frowned upon. Now picture a fantasy scenario in which folks may actually have visited Purgatory, and you can imagine that almost nobody in that culture is too eager to sign up for a million laps around the Mountain of Thorns with their eyes sewn shut. Even beyond selfish considerations, their mages can commune with the thralls. For precious hours, the curse can be lifted entirely, and anyone can converse with the shadow-thralls as entirely normal, sensible people. They can see how the bad magic comes back, bites into them, and makes them do bad things. The combination of fear and pity leads the unaffected people to be compassionate and understanding. When the shadow-thralls start beating them up and breaking things, the normal people try to remember this is their chance to cultivate a ticket to the Elysian Fields through forgiving behavior. When the mages put down the revolt by gentle means, it gives a new generation of thinkers a chance to try to finally understand and break the curse once and for all. Of course, for certain wizards it is also their chance to try to finally understand those long-lost secrets, and to prepare their plans to enthrall all of humanity... [Answer] # Curveball Idea Do commit mass genocide. Do it periodically enough to prevent the shadow-thrall population from reaching a number that would let it overpower humans. However, you only kill, say 30% of them and make it a mandatory thing. Do the population control during a thrall census so that owners can‚Äôt cheat and add massive fines for not taking thralls to the census. Just make sure to keep, give or take depending on your population of humans and thralls, 100 or so breeding pairs of thralls in which to replenish the stock. I‚Äôd say that you shouldn‚Äôt let the thrall population be more than 70% of the human population (resource loss and overpowering humans is the main reason). Also, make them were shock collars set to lethal force to prevent rioting. Don‚Äôt have to take this idea, but I reckon that it would be a cool way for a rebel group opposing this structured genocide to pop up. [Answer] Let history be your guide and make them equals I'd steer clear of the weaker, less intelligent inferior slave race idea. Instead it sounds like what you want is an equal but different war-like nomadic people that gives your country serious challenges with periodic raiding activities. Then look to historical examples and adapt them to your purposes. One example that comes to mind is the interaction between the historical nomadic Scythian people (not to be confused with the later misuse of this name) with the Persian empire (e.g. the [Wikipedia article is fascinating](https://en.wikipedia.org/wiki/Scythian_campaign_of_Darius_I)). In general nomadic raiders can give a static empire real headaches and be surprisingly challenging to conquer. But again, I'd make them equals and not an inferior slave race. Your story will be better for it in a variety of ways. ]
[Question] [ In regards to fantasy dates, they're usually set somewhere between 100 - 9000 W.E (Whatever), but rarely exceed 10,000. Is there a reason for this besides being more aesthetically pleasing? More importantly, what happens when the date becomes too long? It seems counter productive to be writing the year as '300,000,000 BC/AD" So what would happen if it ever came to that? [Answer] Fantasy and real world dates rarely pass 10.000 because cultures don't tend to survive that long. Date systems generally start with a significant event as 0: rise of a king, birth of a prophet, founding of an empire, solar eclipse etc. Between those moments and the fall is rarely more then a thousand years, two thousand perhaps. I figure that if the system becames too broken we would just adopt a new one. The gregorian calendar wasn't the first one we used. Only recently we have been even contemplating time periods longer than thousands of years ago. Having a need for such a system implies an advanced civilization. One who undoubtedly knows many date keeping systems. If we ever spread across the stars a central date keeping system becomes pretty meaningless too. Days and months vary per planet, traveling near lightspeed causes all sorts of weird effects on aging etc. [Answer] Take a look at how real-world calendars have dealt with this. The infamous [Mayan calendar](https://maya.nmai.si.edu/calendar/maya-calendar-converter), for example, counted days from a start point in 3114 BCE, using 5 periods. Each period counted from 0 to 19 then rolled over back to 0 (except the second-shorted period, which had a period of 18). Thus each period represented a set number of days. ``` August 12th, 3114 BCE was 0.0.0.0.1. August 13th, 3114 BCE was 0.0.0.0.2. September 1, 3114 BCE was 0.0.0.1.1. January 1st, 1 CE was 7.17.18.13.1. May 22nd, 2017 CE is 13.0.4.8.13. ``` Using this system the Maya could track dates from the year 3114 BCE up to 4772 CE with ease. You can use something similar to track large expanses of time in your world, especially if you're willing to use periods greater than 20. For example, we westerners might like to use a structure of Year.Month.Week.Day, especially if we were willing to make our months a little more sensible and set them all to 28 days long (1 lunar month). This year would begin at 2017.01.01.01. We don't generally use 0s in our time counts, so we're starting at 1 for each period. Today's date (as I type this) would be 2017.05.01.01 To make this truly useful to track very large dates, though, we should add a fifth period. I would suggest the Great Year - the time it takes Earth's axis to precess a full 360 degrees. A Great Year lasts about 25,800 years; we could divide that up into 12 periods to represent the signs of the zodiac, giving us a period of 2,150 years per constellation. ``` Today's date 01.2017.05.01.01 January 1st, 2200 01.50.01.01.01 January 1st, 10191 04.1591.01.01.01 ``` If you want to go beyond the year 25,800, you could add yet another counter, to track the Great Years: ``` January 1st, 426,255: 16.06.555.01.01.01 ``` For common use, of course, you wouldn't need the first two periods - the current year and date would suffice. The full count would only be used in formal settings, similar to how legal documents often spell out the year in full (Nineteen hundred and whatever). It gets a little convoluted, with all the different values being used, but it can track some pretty darn high dates with great precision. Also, there is an excellent chance that I've fouled up the numbers somewhere up there - I'm a logical guy, but dyscalculia is a thing. Feel free to edit and correct any numbers I've screwed up. [Answer] This is an interesting problem to tackle because it deals with timescales that most of us are very unfamiliar with. My first recommendation to anyone dealing with such timescales is to read Stephen Baxter's book Manifold Time. It's one of the few books I've have seen which truly grasps just how strange life can get when making sense of how things are in the year 1,000,000,000,000,000,000,000,000,000,000,000,000,000 AD. Yes, that makes 300,000,000 BC/AD look pretty tame by comparison, and yes, Baxter goes much further into the future than that! There's a few solutions to the issue you describe which have some history. The first key to all of these is that we are really trying to describe a "time point," and we typically want to do so using a number. The second key to this is that the purpose of such dates is communication. Our goal is to convey the concept of the time point to another individual. ## Cycles Cycles are a very popular approach to dealing with large dates. Instead of counting numbers of days, we count in months, then years. Other cultures, such as the Mayans, had even more exotic cycles. The fundamental reason cycles work is because the events we care about tend to occur on logarithmic timescales. Consider how many things we care about happening in a day. You might have 5-10 points in the day that matter enough to pay attention to. Now think about a month. Obviously you don't pay that much attention to the 150-300 points in the month corresponding to the 5-10 points every day. That'd drive you bonkers. Instead, you have 5-10 really important things to look forward to in the month, like pay day or someone's birthday. Look at a year. You might have 5-10 major events that you truly care about, like a family vacation or a major release of a product at work. ## Shortening We currently are living 2000 years after the epoch of our current numbering system for years. This can be inconvenient, so we are known to shorten it to a 2 character year for convenience. As long as we're certain that '05 means 2005 and not 1905, this approach is very effective. Most time points we want to convey are within one lifetime, so we only need 2 digits. If you think about it, this is really just a special case of the cycles solution above, which only works on cycles of 10 or 100 years (or whatever based numbers your civilization uses). ## New Epochs We're known to invent new epochs from time to time. When we do this, we define a new time point to base everything off of, and do math to convert one time into another. The most famous of these right now is the Unix Timestamp, which counts the number of seconds since Thursday, 1 January 1970 UTC (sans leap seconds). Why was 1970 chosen? Well, there's many reasons but one of the major ones is exactly the issue you describe in the question. If you're counting a number of seconds, that number can get big in a hurry. 32-bit computers could only count to just over 4 billion seconds, so they had to choose a time which meant most times that people in the computer age could care about fit into that window. 1970 fit the bill. Of course, they're running into trouble soon: on 19 January, 2038 03:14:08 GMT, the Unix timestamp will run out! There is often a meaningful time where an epoch gets specified. Historically, many dates where given in terms of the ruler's reign. You might talk about an event that happened 5 years into the rule of King Henry. In more modern times, we defined a very important epoch for humanity in 1972, when we defined UTC in terms of atomic clocks. Nobody had every defined the second so precisely, so there was no way to determine exactly what the current time was when setting the first atomic clocks. The solution was that we defined a new epoch, such that all clocks would read 0 at that time. Interestingly enough, we've also used the act of defining new epochs to go the other way. The single most common way dates are measured in the high-precision community is as a Julian date. For example, a major point in timekeeping forked off 2 additional time systems on Julian Date 2443144.5003725 in order to deal with time dilatation effects that had been unexpected until that point. Note that that date number is pretty big. Julian Dates are based off of the number of days since noon on January 1, 4713 BC, on the proleptic Julian calendar. That odd year number, 4713 BC, was chosen intentionally to be far in the past. It was designed to be so far in the past as to occur before any recorded history (as well as being the conjunction of several cycles deemed important at the time). ## Measuring from the Present This is a bit tricky, because it doesn't fit well with the math, but we measure time with respect to the present all the time. We talk about something that happend 3 hours ago, or 4 days ago. This approach has a disadvantage of being only valid at the moment in time where the date was uttered, but sometimes that's enough. We're used to working with a web of relative times. ## Brute Force If brute force doesn't work, you're not using enough. Humans may have trouble with large numbers, but computers don't. If your civilization becomes highly computerized large timestamps become easy to handle. NTP timestamps are an excellent example. Right now they are 64 bit structures: a 32 bit integer number of seconds which will roll over in 2038 (with the Unix timestamp), and a 32 bit integer number for fractions of a second. However, there is talk of making them 128 bits long. This would be sufficient to measure times as "small as the time it takes for photon to pass an electron," and "large enough to be valid until the universe goes dim." The key to this is that computers can handle these numbers so well. To a computer, the year 2015 is no more difficult to capture than Julian Date 2457023.5. Our number systems, with its place-based notation grows logarithmically, so each additional digit gives us another 10 fold increase in numbers. This works great until the energy cost of storing a 128-bit timestamp in memory starts to become important. But for that story, read Steven Baxter's book! [Answer] It's worth noting that we don't even use full dates (100% of the time) in modern times. Most of the time it's simply 96, 01, 17, etc. To answer your question, official records could contain the whole year while letters and casual reference would likely refer only to the last two digits. Humans generally don't live beyond double digits, so only referring to the last two digits allows others to understand what is meant. Alternatively, the solution could be to add letters. Starting at 10,000 it would be A0000, and the last usable date with that system would be Z9999. This would cover the span of 260,000 years. [Answer] Let's assume that science have taken over the world. And they start counting time from the birth of our Sun. So they go with 4,5 bln. But hey, it's ok if you tell time in the billion years event, but when you go to millions you go 4 mln. And thousands? you go 4k. and hundreds? just write 86. There are events that can't be put in the month/year/century/ bracket. For example the time when dinosaurs walked the earth. You just can't pinpoint "from Monday about 5 o'clock till 5 millions years later Friday around breakfast". Look at different example. When somebody ask you for time do you answer "first day of the fourth week of the middle month of the second quarter of the seventh year second decade of third millennium" or you just go "4.35"? After sometime you just stop counting because YOU DO NOT CARE. Even if you are a deathless Emperor on a golden throne you just go with 40K because you don't care about days or months. [Answer] There are a few precedents for solutions to this sort of thing. The Elder Scrolls series of games uses Eras in its [timeline](http://elderscrolls.wikia.com/wiki/Timeline), while Tolkien's Middle Earth uses Ages in its [timeline](https://en.wikipedia.org/wiki/Timeline_of_Arda) In both of them, these eras are divided not by a set amount of time but by significant events. In the Elder Scrolls mythology, a few are started by someone founding a dynasty or empire, or even by declaration. Some eras are really long, others are much shorter. With Tolkien, the start of specific Ages seems less clear. Regardless, this method allows for ease of remembering how long ago something is while not necessarily bogging things down in super-specific definitions. If your story is in the Fifth Era, and you reference something in the First Era, you can tell - without knowing how long any of the eras are - that it was a Long Time Ago. [Answer] The Human Era or Holocene Era dates events from an arbitrary date of 10,000 BC so that no historic or recent prehistoric dates have to be counted backward. Thus the current year is 12,017 HE as well as 2017 AD. The advocates of that calendar see no problems with dates over 10,000. Astronomers use the Julian Day number, counting the days since January 1, 4713 BC. The current Julian Day number when I write this is 2457893. That is 2,457,893. According to this the value of the Vulcan Old Date in some Star Trek fiction can equal or exceed 140,005. This may be in Vulcan years or other Vulcan time units. <http://wrstone.sdf.org/startrek-timeline/notes-12.html>[1](http://wrstone.sdf.org/startrek-timeline/notes-12.html) Possibly people can use two or more different year counts. Perhaps proclamations and rewards for criminals can give the date both as year 25 of the reign of Emperor Alynomern CCXXXV, 10,001st emperor of the Atlantean Empire, and also year 270,025 since the founding of the Empire. Young people may tend to use the regnal years of the current emperor when calculating their ages, while older people have to use the years since the founding of the empire to calculate their ages. And maybe some people also say the year is 186, counting since the latest war with Lemuria. And perhaps to some people the year is 5,751, counting since the foundation of the dynasty of the present emperor (Alynomern CCXXXV) which is the latest of the recent short lasting dynasties. And maybe in the introduction you can say that the story begins late in the history of Atlantis, "only" 154,825 years before Atlantis sank under the sea! That will certainly give you enough time for Atlantean sequels. The story "Out of the Aeons" by H.P.Lovecraft and Hazel Heald, concerns a legend of the lost continent of Mu that is calculated to have happened similarly far back in the past. > > It was in the Year of the Red Moon (estimated as B.C. 173,148 by von Junzt) that a human being first dared to breathe defiance against Ghatanothoa and its nameless menace. > > > <https://en.wikisource.org/wiki/Out_of_the_Aeons>[2](https://en.wikisource.org/wiki/Out_of_the_Aeons) [Answer] With computers, the date will never be too long. So what if the year is 654,546,534,120,296,145? A computer can easily store and communicate numbers like that. And that far into the future, we could have computers implanted in our brains so we can do complicated arithmetic in our heads, remember everything and communicate as quickly as a wireless data transfer. Whatever problems exist in that year won't include the size of the number. [Answer] What date system would be used If the years got to giant numbers (like the year 3,000,002,017), then a system could be used that writes the last few dates, then specifies how many digits are excluded. How the date would work The date would look like: 8x:17. the 8x would stand for the number of digits in front of the 17 and the :17 are the last digits of the date. This system would be highly versatile as the precision of the date could be specified by the user, for example, a precise, important date could look like this: 0x:3,000,002,017 (or just :3,000,002,017 would work fine) but a quick casual date would look like this: 9x:7. How the date would be said For the date 8x:17, the date could be said formally like: "Eight times seventeen", but in casual speak, the date could be said like: "Eight, seventeen" and it would get the point across well enough. ]
[Question] [ I have a new fluid, called Unobtaniol, which is a room temperature frictionless superfluid. It has the same physical properties as liquid helium, but with less freezing everything. A friend of mine reckons that it would be great for lubricating gears, pistons, various forms of reciprocating arm, worm assemblies, you name it. I'm not so sure. Would this fluid be a good lubricant, and if not, why not? [Answer] We don't aim for lowest friction in lubricants. We aim for appropriate friction. Viscosity or thickness of the lubricant is significant in all uses. We don't always aim for the lightest possible oil, often what's used is a much heavier grease. The choice of grease is appropriate to the load and coarseness of the materials involved. A delicate mechanism would require a very light oil with a very low viscosity. A heavy duty piston or axle bearing often requires a heavy grease, this is to ensure that gaps are filled and the grease adheres to rougher surfaces to act as a lubricant. A very light oil would not adhere in a thick enough layer to allow for the roughness of the surfaces involved. [Answer] Just to clarify: a "frictionless" fluid would have no tendency to coat surfaces - it would "slip" right off. That means a sandwich with it between two surfaces would not protect the two surfaces from one another. Making the frictionless substance bondable may make it work: So consider this the cross-sectional situation between two surfaces A & B with a lubricant,L: -A-A-L-L-L-B-B-. If L is both frictionless AND bonds well to both A and B AND the A-L and L-B also don't interact with L, then you might have a damn good thin film lubricant. (Of course, lubricants have a lot of properties in addition to their modifying the coefficient of friction which determines if they'd be useful or not.) [Answer] I'd say no, unless you suspend the machinery in it. Frictionless sounds like it would be great until the moment you put it on something and it slips off. I don't know that much about the physical properties of liquid helium, but I'm guessing it's not very viscous, so it would not tend to stay put. [Answer] It could be used in pressurized fluid bearings essentially creating an absolutely frictionless bearing. It could NOT be used in non-pressurized non-sealed scenarios because, as stated before it would not stay on. [Answer] I don't think it could BE a liquid without friction. The fact that it has friction allows it to fill a volume. No friction would mean it floats. Maybe minimum friction? But even then it isn't likely to be very useful unless you're trying to keep apart two objects that have very little mass or force and don't want them to be overwhelmed because they're super delicate. Motor oil is super viscous because it's used to keep very dense, heavy objects apart. It definitely has friction though because it sticks to everything. ]
[Question] [ Relating to my earlier question [Is it a good idea to harvest the sun to terraform Venus?](https://worldbuilding.stackexchange.com/questions/236518/is-it-a-good-idea-to-harvest-the-sun-to-terraform-venus) Suppose that we continue to “mine” the sun for hydrogen to be used as rocket fuel. If we continued to do so, would this begin to deplete the amount of hydrogen in the sun and start to lower it’s life expectancy, eventually causing it to explode/transform into a supergiant? [Answer] Assuming you're taking hydrogen from the surface, you'll be lengthening its lifespan. The sun's outer convective envelope, within which hydrogen is cycled from the surface to its interior, doesn't quite reach its actively-fusing core. That core is supplied entirely by its own internal hydrogen; by the time it's done fusing into helium naturally in ~5 billion years, the outer envelope will still be hydrogen, since it won't have been cycled in. So the only effect of removing mass from the envelope right now is to reduce the pressure on the core, and with less pressure, the core burns more slowly. At a certain point, if you deplete the envelope by a significant margin (difficult; we're talking thousands upon thousands of Earth-masses here), you might begin to alter which parts of the Sun are convective. A low-enough mass star is fully convective and taking more mass away will simply shrink it until it can't fuse anything more at all. [Answer] As a rule of thumb, the more massive a star is, the shorter its life is. If I remember correctly, the more massive a star is, the more densely packed are the atoms in its core and the easier it is for them to fuse, resulting in a quicker burning of the available fuel. For a reference, you can use [a calculator](https://rechneronline.de/planets/lifespan-star.php) to estimate the life of a star based on its mass: * A star of 1 solar mass would have a life of 10 billion years * A star of 0.8 solar masses would have a life of 17.5 billion years [Answer] I doubt it. I seriously doubt it. A long time ago in a galaxy far, far away I lived near Coeur d'Alene, Idaho. I remember watching a news broadcast about a lady who was upset because a local golf course had been given permission to draw from Lake Coeur d'Alene to water the course. She was absolutely convinced lake water levels would drop precipitously because of it and demanded that they cease and desist immediately. * Golf courses require about [152.5 acre-feet of water](https://www.gcsaa.org/uploadedfiles/environment/environmental-profile/water/golf-course-environmental-profile--water-use-and-conservation-report.pdf) annually. * Lake Couer d'Alene stores about [2,260,000 acre⋅feet of water](https://en.wikipedia.org/wiki/Lake_Coeur_d%27Alene) Unless you're trying to fuel billions of ships a year, your civilization could realistically draw hydrogen non-stop from its star and, unless you need it to be otherwise in your story, it won't make a measurable dent in the lifespan of the star. and if you have interstellar travel, this is even less of an issue because you could either (a) mine another star or (b) move to another solar system when your star is mined out. [Answer] I did read somewhere that by controlled removal of matter from the Sun one can make it live ~12 times its predicted lifespan while maintaining constant luminosity. Of course, this strategy implies removing a great deal more hydrogen than the amount one would need for Venus. On the other hand, if the goal is to teraform Venus, there are much easier sources of hydrogen available in the Solar system. E.g. the moons of Jupiter and Saturn are almost reachable as a hydrogen source even with today's technology. ]
[Question] [ What bows are used for different situations and what makes them the best choice? In my story a village is only easily accessible in one direction (Tall mountains around it and a fast river behind) with hills the path towards it. What would be the best bow to protect against an invasion and why? If the enemy took the time to climb the mountains that surround it would that bow still be the best option? It's in the medieval era with no magic, the enemy opted for quantity over quality so they out number the village say 1000 to 200. But they only have basic swords and shields(no armour) , Plus they aren't very organized. Also the village had time to prepare. Due to it being surrounded by mountains. It was excluded from the rest of the world only know by a few traders. So they had time to get comfortable. So let's say around five years. But they never slacked off training. The enemy's main goal is to take over because of its geological defensive advantages. But will resort to more deadly means since a siege is impossible due to the river being freshwater. The village can use it for food and water. It is also the enemy's villages main source of water. So they can't mess with the river. And the weather is frequently humid. [Answer] It's complicated Start by forgetting pretty much everything you have seen in movies or the majority of computer and table-top role playing games. Movies and computer games concentrate on flashy visuals while TTRPGs focus on playable rules. Real life is more complicated. Bows can be classified in various ways - by draw weight / purpose, by configuration and by stave construction. Looking only at the construction of the stave there are three types of bow from this period: 1. [Self bow](https://en.wikipedia.org/wiki/Self_bow) - this is fundamentally made of a single piece of seasoned timber, although some fittings may be made of other materials eg horn nocks. When people are referring to an English long bow, they are talking about a self bow that is, well, long. "Long" is not perfectly defined, but most evidence points to a stave that is as tall or taller than the shooter. (For more information, a number of Lindybeige videos are an enjoyable diversion.) The massive advantage of a self bow is that provided an appropriate section of seasoned wood is available, a skilled bowyer can carve it into a bow with a day or so of work (= cheap). The disadvantage is the length of the bow, which makes it unusable on horse back or from pretty much any position other than standing upright. 2. [Composite bow](https://en.wikipedia.org/wiki/Composite_bow) - "is a traditional bow made from horn, wood, and sinew laminated together, a form of laminated bow". These bows can achieve the same draw weight as a much longer self bow in a shorter length (sometimes with superior efficiency), making them usable from horseback and more easily carried in close country. Contrary to most TTRPG statistics, a composite bow and long bow with the same draw weight and efficiency have the same range and ability to inflict damage. The advantage of the composite bow is the aforementioned compactness. The key disadvantages are that they may not be especially weather-resistant, delaminating if they become wet, and they are much more time-consuming to construct (= expensive). 3. [Laminated bow](https://en.wikipedia.org/wiki/Laminated_bow) - this is any bow where different materials are laminated together to form the stave. Composite bows are arguably a subset of laminated bows. The same advantages and disadvantages apply to a laminated bow compared to a composite bow, with the expense and weather resistance being dependent on the exact construction method. For each stave type there are different draw weights. Without getting too specific: * target bows are frequently very low powered, only intended for competition or displays * hunting bows are intended to propel an (often broad-headed) arrow with sufficient force to mortally injure an animal * war bows are intended to propel an arrow with sufficient force to penetrate armour and injure or kill the person wearing it. Potentially any of the stave types above or a metal stave can be mounted horizontally on a stock to create a [crossbow](https://en.wikipedia.org/wiki/Crossbow). Crossbows shoot short, thick bolts instead of arrows - these have flatter trajectories at short range but become unstable in flight beyond 70(ish) metres. The main advantage of a crossbow is that it can remain at full draw indefinitely until it is time to take a shot (as opposed to a few seconds for a bowstring being held to the rear by the archer) and it can be shot from prone or kneeling positions. However, a crossbow is even more expensive than the other bow types and is much slower to reload - against 5 to 1 odds, this probably takes crossbows out of contention. (No, I am not going to discuss repeating crossbows.) Attackers (aka arrow targets) It should be noted that the possession of shields by the attackers is very sensible of them but very inconvenient for the villagers. Shields are great for defending against low-tech missile weapons (provided that the shield-wielder actually holds it in front of them as they advance towards their enemies rather than holding it at their side like a fashionable handbag). A key question is whether they are also wearing armour or relying on their shields alone - see below. So - with the terms defined, what's best for the village? Frankly, it depends on lots of factors. If they know that the attackers have shields but no armour then the villagers can use hunting bows instead of warbows, requiring less effort for each shot. If the climate is quite wet then self bows are probably a better choice than composite bows that will delaminate. Conversely, if it is generally dry but there is lots of climbing in close country then composite bows are a better choice. Regardless of the weapon choice, the terrain-based tactics are key - the villagers must make their stand/s on ground where a chokepoint limits how quickly the attackers can advance and the villagers must attack from multiple angles to avoid the shields. [Answer] ## You probably don't hold the Village I like KerrAvon's answer a lot, but it mostly discusses bow technology. I'd like to address the tactical side. It's a pretty tall order to defeat an enemy that outnumbers you five to one — and if any of the 200 villagers you mention are children or old people, the odds get even worse. Even if this village is compact, it's going to be very difficult to build and defend any kind of perimeter with only 200 defenders. And once you're in close combat, numbers really do provide an advantage. Unless you spend your prep time turning the villagers into well equipped, disciplined, Heavy Infantry (think Roman Legion), I don't think you're holding the village. But that's probably OK, because... ## The Enemy Can't Hold it Either The word guerilla comes to us from Napoleon's invasion of Spain, when the mountain villagers harassed the most powerful army on the planet so thoroughly that the French were using columns of 1,000 men to deliver routine communications. So go the guerilla warfare route. Spend your prep time stashing food and weapons in the mountains. Scout sites for camps. Train in moving quietly through the wilderness. When the invasion comes, abandon the village — bring all the food, and burn all the buildings. Ambush the enemy column, but don't get drawn into a general engagement, just kill a few, and let the rest arrive at the empty husk that was supposed to be their objective. Now hit every supply column that attempts to bring food, and every scouting party that goes looking for firewood. The first winter will finish them off. ## Crossbow Tactics The original guerillas would issue a single bullet to each soldier, because they knew they would lose any prolonged engagement. The plan for their ambushes went like this: * Half the soldiers fire and charge with bayonets. The other half remain hidden. * If the enemy breaks, you kill them all. * If they enemy holds, the hand-to-hand group disengages, and flees back to the woods. A single volley from the hidden group discourages the enemy from following. These tactics would translate pretty well with crossbows — like early firearms, crossbows are powerful, easy to learn and slow to reload. So your villagers train with crossbows and simple melee weapons. The emphasis is on transitioning from sudden volley, to savage attack, to organized retreat. [Answer] ## If you must use a bow... Use a high poundage self-bow with plate cutter bodkin arrows. Not many arrows can get more than an inch or two of penetration through a shield regardless of bow type, but a heavy warbow with plate cutter bodkin arrows can wound someone through a shield if they get careless about how close to themselves they hold it, or if their shields lack a boss. You also don't want to use composite bows in wet environments because they risk coming apart on you. ## But preferably you would use Roman Manubalistas and Pilla Bows are great as a battlefield weapon because of their rate of fire and mobility, but when defending a narrow pass like this fortifications, range and stopping power become far more important. No anti-personnel weapon prior to the invention of gunpowder packed more range and stopping power than Roman torsion spring weapons. By establishing a fortification blocking off the pass, your defenders can use light ballistas to take out enemy archers at nearly twice the range that they can shoot back while your fortifications can be used to block any arrows they try to fire at you if they do close the distance. And if necessary, you can also have a few heavier ballistas to threaten any attempt by the enemy to set up siege equipment. This basically forces them to charge your position with ladders which is where the Pila come in. A pilum is very similar to a plate-cutter bodkin arrow, but instead of attaching the head to a thick wooden shaft, they would place a thin iron shaft at least a half a meter long behind the point. Because of this feature, a pilum's tip could punch a wider hole than the shaft allowing the shaft to pass cleanly through the hole. Modern tests of pilia show them to be able to stab a shield user through a shield even when held at full extension whereas arrows rarely get more than a few inches of penetration before getting bound up in the wood. Because pilia can be thrown in rapid succession, once you force the enemy to charge your fortifications, each defender can kill one enemy after another with these thrown weapons because the shields are so useless against them. The enemies of Rome often used armor in addition to shields because of this exact threat, but since your enemies don't have that, they will get slaughtered. [Answer] You mentioned mountains surrounding village - you might use them instead. Forget about bows, if the pass to the village is narrow or steep enough defenders can easily win against attacker by using rocks. No amount of shield or armor can help you against blunt trauma inflicted by a heavy rock falling on your head. Or rolling over you. Defenders can make a palisade on the hill and keep a sizeable number of rocks behind it. Or logs if rocks are harder to come by. When attackers start climbing up the hill, just let these rock roll down the hill at the attackers. Then, number of attackers is all of a sudden much smaller and you finish off survivors by any type of bow, preferably crossbow so everyone can help with target practice. (I do not recommend slings. You need quite a lot of training to be useful with that, and even then range isn't all that good. It is a great improvised weapon but when you have time to prepare crossbow is a much better alternative) Additionally, you have mentioned a river goes through the village and then to the attackers. Have you considered that village can divert the river, killing all attackers without a single arrow fired? Yes, it might be a bit difficult to do it if the river goes through a deep canyon, but given several years to prepare it would be still quite doable. [Answer] The types of bows I'm aware of, besides construction which has already been covered, are: 1. Short bows, longbows, (both are self bows) 2. Recurve bows (often composite but can be made out of a single piece of wood) 3. Modern compound bows (which I think aren't an option) So here's the issue, it takes a lifetime to be good enough with a bow to actually use it effectively in combat, or even hunting. So if you want your defenders to be good with them, enough to fight off hordes of enemies, you need a reason for them to train with bows from childhood. E.g there's a river right beside them maybe they do bow fishing, or hunt game, fairly believable. So what kind of game are they hunting, what materials are available for them to build bows with, put these things together and do a little research on ancient civilizations and bow tech and come up with a bow yourself. A little note, a cut-off village like that would have no chance of having lots of Iron or even copper. In Ireland, in the dark ages, a short sword was worth 40 cattle, that's a fortune today let alone in 900AD. Metal was too precious to be used in a way it might get lost, except in war. So stone or obsidian, which can easily be explained by having one of the mountains be a dormant volcano, for arrowheads. good luck with your story and just keep writing, I wish I did. ]
[Question] [ Premise In the movie [Gravity](https://en.wikipedia.org/wiki/Gravity_(2013_film)), gravity embodies the persona of the film by virtue of its absence. It purportedly leaves the audience with a sense of fear of the chaotic zero-G environment and likewise leaves them with new respect/appreciation for our gravity-exerting Earth. In stark contrast, I would like to portray a utopian zero-G environment where the space farers are floating about merrily without a care in the world. Gravity in my setting is actually the source of conflict. In my futuristic setting, humans are colonizing space. Here is some basic info: * Number of supply ships: 5 * Average supply ship population: 2000 * Purpose of mission: supply vital resources/human capital to fledgling colonies * Length of voyage: 400 years * Crew survival method: genetic longevity and new generations (no fancy hyper-sleep) * Flight path: computer navigated, predetermined, unalterable * Landing: can be over-ridden by pilot * Ship Fuel: Limited * Edible Food: Unlimited These ships do not have artificial gravity. Instead, the space farers in my setting are utilizing future technology: genetic modification such that humans are not prone to muscle atrophy or any other adverse effects of extended zero gravity habitation (calcium loss, vision loss, etc). However, as a double edged sword, this futuristic zero-gravity setting also sets the stage for a dark and unexpected outcome. Namely, extreme barophobia (fear of gravity) has manifested itself in the minds of the crew in all five ships. There was a small gravity chamber to acclimate the crew for when arrival day was near, however it has since been destroyed in a fearful rage by the crew. The potency of the barophobia is extreme. The crew drifts about in a fantasy-like existence, floating around the supply ships happily at times. However, dark, disturbing conversations take place amongst them about what happens when the ship arrives and a gravity-exerting planet will be close to them. The captain said: > > "Fear not, I am the captain. Though I cannot plot my own course, I can > over-ride any landing commands issued remotely by a computer. I can definitely keep > us from landing on the planet." > > > The exact cause of the barophobia, the degree of the phobia's potency as well as prevalence all remain unexplained. Though speculation about the relatively new advent of increased human longevity and its effect on the human psyche (especially on an extended space flight) are much debated. Problem When the colonists on the destination planet excitedly made contact with the arriving colony/supply ships they were mortified to hear that: > > "We, the supply crew, have no intention of following-through with the > re-supply mission, nor do we plan to cooperate in any facility. Furthermore, we do not plan to step one foot on > your planet." > > > After spending incalculable amounts of fuel, resources and time, the supply ships' crew's crippling fear of gravity is jeopardizing the mission's directive as well as endangering the lives of the colonists who are planet-side and in dire need of the supplies. It is at this point that the colonists on the planet realize that their lives and even the future of the colony itself is at stake. There were no contingency plans for such a seemingly absurd turn of events, but something must be done. They try to formulate a set of protocols to weigh the options. Question: What protocol could be brought to bear to save the fledgling planet colonists? They need the supplies to survive, but the supply crew refuses to help due to extreme barophobia. The supply crew refuses to land on the planet. Question Rephrased: To reduce the "story-based" dimension, you may boil the question down to: What protocol could be brought to bear on a supply ship that is not cooperating with colony supply? (But bear in mind that barophobia is the cause of their lack of cooperation). Further Clarifications * Success metric: survival of the planet colony * Timeline: 5 years max (the supplies are direly needed, some colonists will die after 1 year) * Planet's military: Non-existent (they are fledgling in nearly every aspect) * Planet's Ships: Non-existent (they bought a one-way ticket. Their original ship has been converted to a building in which they find refuge from the planet's atmosphere) * Prevalence of Phobia: Everyone, all supply ship space farers are super barophobic. [Answer] I see an interesting way of dealing with this (other than the excellent answers so far!). If the supply ships arrive all at once it would change the answer a bit, but it seems like the question asker and many answers here assume that it's not a simultaneous thing. The OP states: > > The crew deviate into a fantasy-like existence... [h]owever, dark, > disturbing conversations take place amongst them about what happens > when the ship arrives and a gravity-exerting planet will be close to > them. [Emphasis mine] > > > Over the generations, this sort of phobia – where the crew is concerned with even being close to a gravity well – would turn into almost a religion. An ark ship travelling for generations could develop its own lore, traditions, and faith... meaning that arriving at the planet would be Armageddon, and the colonists would be the anti-christ(s). The (prophesied?) Captain, in turn, would be a sort of Messiah, or, at the least, the Pope. The colonists, then, must break this unified front into smaller groups. Fanatics are obsessed with purity. It's not enough to know who is opposed to gravity – everyone is – you need to know how tainted people are by gravity. How many people have passed through the parts of the ship that were able simulate gravity? Whose ancestors used those gravity simulators? Whose ancestors boarded the ship last (and were in a gravity well longer than others)? Alternatively, genetic enhancements probably were unevenly expressed – so who shows signs of muscle loss, weak bones, etc? Purity becomes paramount, hereditary even, and potential traitors are everywhere. The colonists can play on these tendencies. First, they should broadcast a series of pleas from families desperate for supplies – begging, please won't you send us the food/medicine/technology we need to live? Make the stories as sob inducing as possible – really ham it up. Next, broadcast a message (ostensibly addressed to the captain) saying: > > We understand your plight, we are sensitive to your beliefs. We would never ask the purest of you to come down... but what of the > impure? What of the criminals? What of the malcontents? We've received > messages from some on your ship saying that they long for the > pull of gravity. Why not send us those? > > > As you can imagine, the message sends the zealots and high priests into a frenzy. Cries of 'HERETIC!' echo down the ships halls, neighbors rat out neighbors, minor scuffles break out ship-wide... The crew would review who tuned in to the sappy pleas from the colonists, and soon the saintly Captain (betrayed by his people's the lack of faith), must, with a heavy heart, sentence these sinners to the ultimate punishment: being sent down to the planet. How do the colonists convince the crew to send supplies with the sinners? Offer the ship an out. The ship's problem is twofold: they can't escape orbit because they can't set destinations, and they can't go on forever because they don't have fuel. The colonists probably don't have the answer to either of those problems... but the crew doesn't know that. The colonists can just lie: > > We're all reasonable people, and both of us want things. Send us some supplies with the heretics, and we'll load the shuttles > with fuel so you can be on your way. When the shuttles return to you, we'll transmit the access > codes to reset your ship's destination. > > > If enough supplies are sent, they can stiff the crew and just let them die in orbit. If those supplies aren't enough... well, more strife, as they say, must be stirred: > > You didn't send enough supplies for us to give you the fuel and the > codes. We want to help you but we need more (for our children!). What of the people on the planet side of the ship? Surely > they've already been tainted, they've... Felt The Pull. They deserve > to be here anyway. > > > An itching sensation in the back of the planetsiders minds will stir, a concern they weren't even aware of before. Families will pack small bags of the essentials, and calmly but quickly move towards the space side. Soon what started as a few people will turn into a zero-g stampeed. Everyone planetside will scramble to get to the space side of the ship. Riots and desperate pleas of at least take my children! abound as The Captain declares martial law. As this is going on, the colonists load the shuttles with their police force, armed with what game-hunting projectile weapons they can muster, and head back to the ship... where the docking bay is planetside. With martial law declared and all the ship's security occupied with holding back the planetside exodus, it takes some time for the crew to realize they've been boarded. Confusion reigns. Blockaded doors. A shootout outside the bridge. And at last, silence settles as a ship-wide announcement from the colonist commander crackles over the speakers: > > Your religion... was right. > > > This is Armågeddon... and you lost. > > > Prepare ỷourselves, oh ble̐ssed peo̅ple, prepare to Fe̲e͋̃̾l Th̖ͧe̙̝̫̻͔͇̐̐̎̂ P̿ͨu͌ll until the last day of ¥our > genetiĉally lengtheñed lîves. We are the f̝̋a̚l̯̿ḷe̒nͨ. > > > And we're here to take you to hell. > > > [Answer] Part of the plan. The sponsors of the mission knew that the descendants of the original crew would go insane. In fact, the genetic modifications made to the original crew combined with subliminal prompts built into the ship and living quarters guarantee that this particular phobia will emerge. Prior supply missions of this sort ran into all sorts of spontaneous, random mental illnesses and phobias. Some of these were extremely disruptive. By channeling the predisposition to phobia into this one particular phobia, solidarity and unity among the crew is maintained. When the colonists make a credible threat to claim the ship and supplies on board, the desperate and terrified crew responds with force, wiping out the colony and themselves in the process: this was the intent of the persons sending them in their surprisingly heavily armed cargo ship. A distance of millennia and generations make it difficult to sustain a willingness to kill our fellow humans. But the possibility to fear the unknown is hardwired in us. [Answer] This is a supply and demand problem. The planet dwellers have a supply of humanity and pleas, but the ship crew does not have a demand for those, as stated in: > > "We, the supply crew, have no intention of following-through with the re-supply mission, nor do we plan to cooperate in any facility. Furthermore, we do not plan to step one foot on your planet." > > > The planet dwellers have demand for a missile to shove up the ship crew's exhaust ports, but they have no supply for it as stated in: > > Planet's military: Non-existent (they are fledgling in nearly every aspect) > > > As it stands, the planet dwellers have nothing that the ship crew might want. They are as entitled to getting supplies from the ship crew as a beggar is entitled to alms. They better come up with something to trade that might be interesting enough to overcome the ship crew's fear of gravity. Out of my head I can think of a few things: * Drugs. Habitable planets in sci-fi settings usually have arable lands, which are a major part of the production chain of cannabis, poppy, and psilocybin. They can also grow coca plants, which are used to make crack cocaine. The latter is specially addictive enough that junkies will usually overcome whatever fears they have in order to get a fix. * Sex. Yes, I know this is mean. * Treasure. Some things are just more valuable than money. The planet might be the location of the secret codes needed to destroy the Death Star equivalent in your world. Or it might contain a portal to Shangrilah, or an infinity stone. * Control of the ship. If the planet dwellers have hackers among them, they might be able to compromise the ships' drivers somehow through ransomware. * Fuel. As stated, the ships' fuel is limited. * Silence about the crew's operation. Someone paid to build those ships, to fill them with life support, supplies and fuel, and to dispatch them as couriers towards the planet. The crew will have to face the wrath of those who bankrolled them should they fail their mission. The planet people will rat them out if they don't deliver. [Answer] I can't remember the books, but in several early 19th century novels the fear was pirates, cannibals, or disease. What the characters in these books did was send out a one, two, or three person row boat to explore the coastline, help the shipwreck victims, or deliver the supplies. Alternatively, the crew could just throw the supplies in the water and hope they wash ashore. Another alternative was for a smaller vessel to come out from the shore to the ship to take the supplies, do customs inspection, or collect taxes. In your high tech world, the crew could deliver supplies with an automated lander, or dead drop supplies, or have a few brave souls deliver the supplies. Have a space station crewed by locals to take deliveries in zero G, or send up a local ship. [Answer] Actually, your barophobia may be more than a little justified. Humans who spend a lot of time in deep space without gravity (regardless of the handwavium used for muscular and skeletal dystrophy and the like) simply won't be used to gravity wells, and would find planetary life crushing for a while at least. Additionally, your space ships (if designed correctly) will want to sacrifice the reinforcement of atmospheric landing capabilities for lower mass to move between the colonies, saving precious fuel for pushing around more supplies. SO; the answer seems to be shuttles. Each transport ship has their own supply of shuttles (there's your additional mass tradeoff) and they are flown down to the colony remotely full of supplies. They can either be remotely piloted back, have a colonist do it, or left there as a 'gift' to the colony who can use them for their own purposes. Your ship's crew don't ever have to enter the gravity well. In such an instance, you even save fuel for the resupply phase as you have smaller masses launching from the surface in the form of shuttles, potentially saving the fuel cost of getting the entire transport ship in and out of the gravity well. If the shuttles need to return (I'm assuming here that the supply ships are not on a one way trip; that wouldn't be an efficient use of the resource) then you're still saving fuel via the rocket equation by comparison to lifting the entire transport out of the gravity well. As has been said by other answers, this condition has probably been anticipated and this would seem to be the logical answer that ensures everyone gets what they need in terms of both physical supplies and psychological support. [Answer] I don't think this would be a problem. At the point in future history and space travel you describe they would have already conquered the hurdle of putting stuff into space cheaply and with ease. The people suffering from barophobia would never need to leave their ship, because they could easily get re-supplied by drones which bring things up, and could easily send down whatever they have to in drop-pods. As for the colonists ship: maybe they scuttled their big ship, but surely there were smaller ships, shuttles. They wouldn't scuttle them all. They'd need them. Plus, no colony would ever go to a new planet without having the ability to build things. How would they get started otherwise? Your answer is drones that bring up supplies, and drop pods that drop supplies. And maybe a healthy does of Paxil. [Answer] You already got some great answers on what to do when it comes to the point where the crew suffers from barophobia. I'd argue that, depending on how the supply ships got into the planet's orbit, the people on them would probably be quite used to acceleration. I mean, they have to brake somehow, right? They have to correct their course and maybe decelerate for the last leg of their voyage (again, depending on their method of travel). The gravity of your planet wouldn't feel very different. I think, agoraphobia would be a much bigger problem after they'd leave their landing shuttles for the first time. But if it comes to your situation, your society is advanced enough to genetically engineer people to be more efficient in space. I doubt, they'd want their space mutants subjected to potentially perilous landing maneuvers or give them the possibility to desert on the planet. Maybe the barophobia was intentionally instilled in them by the planners of the voyage. Who's going to fly your ships back for the next supply run in 800 years ? So automated resource drop pods are probably part of the initial plan. [Answer] A new Race to Space What is the makeup of the planet, is it a single colony or has it expanded to separate states; or even just separate factions? The suppliers may not want to come to the planet, but maybe they are open to the colonists coming to them in exchange for [see @Renan answer]. I would add that just genetic diversity may be a tradable commodity, as both the colony and ship would want to reduce inbreeding. Regardless, the colonists need to get to space in a relatively short time period, ramping up the needed industry and working with information and expertise provided by the supply ship in order to outpace their dwindling food resources. If there are rival countries/factions, they may each be pursuing their own program or find they need to work together for the common good. ]
[Question] [ Elves in fantasy are commonly depicted as having long life spans and that applies to my story as well with Elves on average living between 250 and 270 years. The question is how would this work and what evolutionary pressures would cause a group of divergent hominids to evolve into such long life spans? Here's a previous question I've asked in the same story. [What evolutionary pressures would lead to Orcs?](https://worldbuilding.stackexchange.com/questions/167531/what-evolutionary-pressures-would-lead-to-orcs) Note: Magic does not exist in my story. [Answer] Not everything has to be directly driven by adaptation. Consider everyone's favourite mammal, the [Naked mole-rat](https://en.wikipedia.org/wiki/Naked_mole-rat). They live in low oxygen, high carbon dioxide tunnels and have to deal with inconveniences like [occasionally tunneling through a nest of angry ants](https://blogs.sciencemag.org/pipeline/archives/2019/06/10/fast-pain-relief-in-only-seven-million-years). Result? they're extremely pain insensitive, can not only tolerate atmospheres that would kill other animals but survive there for quite a surprising length of time. Moreover, they have a fascinating resistance to cancer, which isn't entirely understood as yet. They seem to do better at producing error-free proteins, and their cells are less prone to uncontrolled proliferation. Their ability to lower their own metabolic rates during lean times reduces oxidative damage caused by metabolism. These things all help to combine to drive a surprisingly long lifespan for such a small creature... perhaps 30 years, simply because they're resistant to a bunch of common ways for other animals to die as they age. Now, I'm not necessarily suggesting that you make your elves like naked mole rats, because although that would be awesome and definitely buck the trend of stereotypical tolkienesque elvishness it is perhaps a bit of a long way from anything that might be called elfin (though, do contrast with the Falmer of the Elder Scrolls). Nonetheless it does show how interesting environmental adaptations can lead to knock-on effects that are useful in themselves. [Answer] There are basically two main evolutionary drivers: 1. 'Survive long enough to have babies'. These are the pressures that are going to have a species develop claws, run faster etc. 2. Sexual selection. That is, even if a specimen is surviving and reproducing, within the species certain traits might be being selected for and in the long run a species develops peacock feathers, or horns that are too big etc. So you can use these two drivers to come up with some scenarios: eg: * For some reason elves have babies at a later and later age, and so need to have better longevity to survive to this long age. * For some reason, older elves are more attractive, and so develop longevity to an absurd degree. But of course - you need an explanation for those 'for some reasons'. Perhaps elvish hair grows very slowly, and it happens to be the 'peacock' trait that elves are selecting for - therefore the older and longer living elves end up being selected for. (The trait could be anything, perhaps 'telling stories of travels' is the trait being selected for, perhaps wrinkles). An explanation for why elves might have babies at a late age - perhaps young elves are very fragile, and also elves require some very rare element to be healthy, and so a very long (decades) gestation period is advantageous, being cocooned inside the mother has she wanders the world slowly absorbing this rare element. [Answer] A slow heart rate plays a major role in life expectancy for example, The smallest known mammal the Etruscan shrew has a heart rate of 1,500 BPM and a lifespan of 2 years. The largest land mammal Elephants have a heart rate of 30 BPM and a lifespan of 80 years Tortoise have a heart rate of 10 BPM and a lifespan of 180 years Bowhead Whales have a heart rate of 8 BPM and a lifespan of 211 years Greenland sharks have a heart rate of 5 BPM and a lifespan of 392 years Humans, with a mean heart rate of 70 b.p.m. and a life expectancy of 80 years, are an exception to the relationship between heart rate and life expectancy shown in animals , as their life expectancy is higher than that predicted by their heart rate. It has been estimated that a decrease in heart rate from 70 to 60 b.p.m. would further increase life expectancy from 80 to 93.3 years in humans. Studies also show that restricting food intake in mice and monkeys can increase their lifespan up to 30-45% Other factors that influence life expectancy is a healthy immune system and a good quality life. In order for your elves to live up to 250-270 years they must have a slow heart rate around 15-20 BPM , They would only consume a small portion of food once a day and should have a superhuman immune system free from diseases and stress. [Answer] Rather than suggesting how they would live so long, I will suggest that the answer to why they live so long falls in line with the Grandmother hypothesis. This hypothesis suggests that the reason humans live many decades after menopause is that they can still pass knowledge down to their descendants, and can still help care for children. These actions ensure that the grandmother's genes continue to propagate. Elves are typically portrayed as incredibly knowledgable and wise, so it would make sense to have tight-knit family and community groups in which the older members continually pass on their knowledge to others. The older the grandmother lives to be (or great-grandmother, and so on and so forth), the more knowledge she will accumulate. She will also be able to provide care and assistance to increasing numbers of offspring. [Answer] At least [one](https://health.usnews.com/wellness/for-parents/articles/2017-03-09/5-benefits-of-having-children-later-in-life) source suggests that having children later in life helps promote longer lifespans for women. This could mean that being more selective about children will result in a lengthening lifespan, and could also contribute to the aspects of elves from some fantasies eventually being in decline, population wise. [Answer] They keep having babies the whole time. Genetic fitness is determined by the number of offspring you leave. I may be the awesomest, smartest and best looking but if I leave 0 offspring I am an evolutionary dead end. Among other variables, the number of offspring one can have is limited by one's reproductive lifespan. Humans do live on after they can no longer reproduce; possibly because having grandparents without their own children confer a survival advantage to grandchildren. Your elves, however, crank out the pups for as long as they live and plenty of them. The longer they live, the more kids and so the genes for long life are selected for by virtue of pure numbers. The older you can get the more kids you can have and so the more genes you contribute to your gene pool. [Answer] Elves altered their DNA artificially. They used artificially created viruses to change parts of their DNA with parts of DNA they extracted from other creatures. They assimilated cancer protecting parts of genome of Mole Rats Starfish Prime mentioned, they assimilated parts of genome of whales as Pierre mentioned. Also they have parts of genome from elephants (probably, its reason why they have strange shape of ears) and owls (so they have night-vision and acute hearing), and lot of other animals. So, Elves become chimeras, results of artificial evolution, with mixed DNA from different species. Even if they look mainly humans, they are not humans any more. So, their longevity is not natural, they live so long not because there is natural reason for this, but because they can. [Answer] A major enemy of lifespan is DNA replication errors. Extending lifespan is about both preventing replication errors, and detecting/killing faulty cells. Human bodies have become fairly good at that, with a variety of mechanisms to do that; and this buys us 80-100 years. Better mechanisms are possible, and the elves have them. [Answer] They breed late in their lifecycle - either driven by economy, religion or customs they are not allowed to breed until late in their life time. This gives evolutionary pressure as only those who lived for long time in relative health are given opportunity to have offspring. Make the age of breeding related to average lifespan to drive it even further. [Answer] ## Arctic Elves: [There is a known trend that organisms that live in extremely cold conditions tend to have longer lifespans than organisms that don't](https://www.realclearscience.com/blog/2015/04/cold_may_be_a_key_to_long_life.html). Some famous examples of Arctic Species with extremely long lifespans are; the [Green Land Shark](https://en.wikipedia.org/wiki/Greenland_shark) (400 yrs), [Bow Head Whale](https://en.wikipedia.org/wiki/Bowhead_whale) (200 years), [Arctica islandica](https://en.wikipedia.org/wiki/Arctica_islandica) (500 years) If you wanted to create an ultra long lived organism, having them live somewhere cold might be a good place to start. Successive rounds of evolution could then extend this life time, if for example organisms tended to reproduce later in their lifetimes instead of earlier. This is partly why Gallapagos Turtles have evolved to live so long; they can reproduce right up until the time they die. So hopefully this is a good start for how you could create a long lived species like elves. [Answer] According to [Morgan Freeman](https://www.youtube.com/watch?v=ztoJVKXkc4M) extended lifespans are a product of a hostile environment. Extending the span of mature competency gives a creature a greater chance of survival than just reproducing quickly or having an early appointment with death which gets rid of the aged when food gets scarce. [Answer] Consider: Why do humans die of old age? There are a few aging hypotheses, which off the top of my head are: 1. we produce "reactive oxygen species," which are molecules that damage cells, as intermediates when metabolizing nutrients. They are transient due to their instability, but the damage they do to the body over decades is non-negligible. solution: studies have shown that a restrictive diet (eating the bare minimum and even going as far to say not expending excess energy) leads to significantly longer lifespans in mice (and presumably humans and all other animals). It's much easier for me to believe that elves show great restraint in their a petites, and are not very physically active. Telomeres in our DNA: you can google this, but long story short, we have extra DNA that gets shorter every time a cell replicates its DNA to split into two cells. If you run out of this extra, you start getting into coding DNA (presumably) causing issues with cell function which lead to programmed cell death (apoptosis) Accumulation of mutations: random chance events cause mutations of long time periods. Look up how cancer cells form on google for more information. ## there are more I'm sure, this is just from my knowledge And next, we get into what the other posters have addressed. Humans never really had evolutionary pressures to fix any of these problems, cause we were gettin' banged all up on by saber toothed tigers and also killing each other en masse since we found out which end of a bone club to hold. If those pressures existed, it is not unreasonable to assume that long lived humanoid species could exist. We're already pushing the limits at like 120 years old... That's pretty insane compared to 500 years ago when you had 10 babies just to have two that lived to adulthood and break even on the population of the next generation. Anyways, for potential solutions, off the top of my head: more antioxidants to neutralize the ROS, low apetites/not much physical activity, and long telomeres, or a DNA polymerase that can copy telomeres all the way to the end so that they do not get shorter with subsequent replications. That's a great start! [Answer] How: Why do turtles live long ? Their metabolism is a bit slower than us and they continue to grow very slowly almost all of their life. That why elves are a bit taller than humans. Evolutionary pressures: Their knowledge has become too complexe to handle a long time ago and the expression of it is what attract them sexually. This was the time before writing was invented by men (at least we did that). It basically takes a century for them to master their native langage properly and begin higher educations. That repetitive learning process stuck them as "child" for a hundred years, meaning it takes this amount of time for their first gametes to appear. [Answer] Biological immortality exists in the real world. [Biological immortality](https://en.wikipedia.org/wiki/Biological_immortality) means that a creature's annual mortality rate does not increase with age after it reaches adulthood. Biologically immortal creatures will eventually die from accident or disease, but they never "get old." This is in contrast with humans, whose annual mortality rate keeps increasing until it becomes almost certain that the individual will die within the next year. [Answer] You have to understand where fantasy comes from and from who it comes from to understand the metaphors involved, along with knowing all world history and Biblical history helps — so buckle up and enjoy :). Tolkien, who wrote Lord of a Rings, is usually credited for creating this fantasy world with the different traditional fantasy races, humans, elves, orcs, dwarfs and hobbits. Tolkien was very much a Catholic, meaning that his identity and his relationship with God combined with the entire old Jewish roots are what allowed him to create these great worlds of brilliant imagination. For example, the ring in LOTR represents sin, so when one is in a state of sin, or when one puts on the Ring, they (spiritually) are now very visible to the dark forces. Naturally, orcs are spawns of these dark forces, as was depicted in them spawning out of the earth in the LOTR series. Biblically, in the time of Adam and some years after, humans were hundreds of years old; this is the time of the Oddessy and Illiad and great giant humans (cyclops, Nephilim) — all the legendary stories were true. Great warriors like Achilles danced and dominated their way around the battlefield. Then, at about the same time as The Flood, God had enough and [said](https://biblehub.com/genesis/6-3.htm) decided that humans will not live longer than around 120 years. God Speaks, and it happens. Elves then are a metaphor for a race of better humans that existed in the past. Historically this was when God literally walked with Adam on the earth. This is why in LOTR, the elves are seen as never changing, never aging; they hearken back to a better time in history who also had special (magical) powers. This is just skimming the surface of it, but you could google Catholic Analysis of LOTR. I'm sure oceans of ink have been spilled in this path we are going down, books even who can explain this much better and more accurately in all its details that I can. Enjoy and God bless. ]
[Question] [ In a world based on [secular humanism](https://en.wikipedia.org/wiki/Secular_humanism), the powerful strive for universal well-being and individuals prefer the long-term profit for all to the short-term profit for one. Because everyone is striving for universal well-being, sustainability would be highly important, leading to a post-scarcity civilization. Now, what social mechanisms would demotivate the bully and favor the selfless? Today it's a bit the opposite; although it is tough to us to be kind and share we get the image that the people on the top are big greedy bullies that are doing more wrong to humanity than right. Kind and sweet people are also often depicted as soft, without will and easy to break. A very bully point of view if you ask me. Hence my question, I would like to know how a society where its profound interpersonal and social structure favors the selfless could be. There are already some very interesting and contrasting answers. I thank you for that. [Answer] ## Yes. A culture where the wish for a specific type of social approval surpasses people's desire for material possessions. The core reason why our current day societies favor "bullies" and not kind people is that what most people desire above (almost; we'll get to that soon) all else is money. Money is power. Power lets you make even more money. And so the cycle continues. The unrestricted acquisition of money is something which by it's very nature cause misery and suffering within the general population/world. --- To fix this all you need to do is make people want something even more than they want money: specifically, praise from society and close peers for being noble and honorable (good) people. --- The good thing is what most people actually want most of all isn't money but instead approval and acknowledgement (though not specifically that due to being a good person). The bad thing is what society approves of and gives acknowledgement to, is people with money. So to attain the status they desire people typically try to gain money. --- Now how and if this is possible is something for another day. Certainly it couldn't simply arise spontaneously. That's just not how culture works. It might however spring out of shifting demographics, job markets (or rather a lack of) and advancing technologies. Which is good because all of the latter is happening now. [Answer] Yeah, good question. What you're asking is essentially, "How could we fundamentally change human nature?" Since the beginning of recorded history, people have wanted basically the same things: basic needs like food and drink and protection from the weather, sex, love, amusement, prestige, power. In almost every society in recorded history money is a way to obtain many of these things. G. K. Chesterton once wrote (couldn't find the exact quote with a brief search, but this is the gist of it) that the problem he has with many utopian schemes is that they assume that all the hard problems are solved, and then discuss at great length how they will solve the remaining easy problems. For example, he said, they will assume that in their utopian society no one will want more than his fair share, and then they will discuss whether is fair share should be delivered by balloon or automobile. I think the only real solution to the problem that the world has ever seen is the solution that you're ruling out: religion. People can be and have been convinced that they have a responsibility to God or the gods to be considerate of their fellow humans. Without a demand for morality coming from such a higher source, why should anyone be anything but selfish? Perhaps you could create a society where doing good for others has rewards. Capitalism has been successful mostly because it rewards people for producing products and services that benefit others. The way to get rich in a capitalist system is to produce something that other people want. But it only works to the extent that other people can afford to pay for it. Perhaps a sufficiently clever person could invent a social or economic structure where you could derive some clear benefit by helping the poor. But no one has succeeded in doing that. Oh, it's easy enough to say, Why can't we create a society where people get praise and honor for helping the poor, and where people are willing to sacrifice material things in exchange for this praise and honor? The reason we can't is because that's just not how real human beings work. You might as well ask, Why can't we create a society where people enjoy being poor and starving to death? That's probably easier to achieve. [Answer] Please pardon the length, but this topic is built upon a complex subject. Most people naturally desire social approval and a feeling of contributing to the world - altruistic behavior does not require a religious motivation, so explicitly secular societies do not need special external reasons for people to behave in socially beneficial ways. Many people in the world give quite generously to altruistic causes even when they are not religious (likewise being religious does not guarantee someone behaves in altruistic ways or even prevents people from being hateful bigots at all). There will always be a segment of society which does not wish to engage in social behavior, but the vast majority of people would prefer to behave in ways which gain social accolades (or at least avoid social approbation). Before some indulge in silly fantasies of a communist utopia if we just got rid of money, or that somehow attempting to purge all forms of [publicly visible] private motivation will result in a kind of post-scarcity transcendence, they should remember the wise words of Adam Smith: It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from regard to their own self-interest. People improve their own position by providing things other people want (regardless of whether or not you think they should want that particular thing). You are better off, they are better off, everyone is better off - no altruism required. Sure people could try to cheat you, but if word of that gets around, they quickly find few people are willing to trade with them (or even want to socially engage with them). Thus maintaining their good reputation, by providing good value to others, is vital to their future self-interest. If you demonstrate that your values are for cheap goods without regard to environmental impact, the incentive is for people to provide exactly that (providing exactly what people actually want) - if your demonstrated values are that you will pay a premium for environmentally sustainable goods (or providers of goods and services who otherwise behave "ethically"), many will attempt to provide what is desired (hence the massive corporate shift toward "green"/"sustainable"/"fair trade" products). People just need to demonstrate what they value, and that is what will be produced as well as possible (needless to say there are plenty for whom this is merely virtue signalling on both sides of the transactions - in which case this is the problem where what is actually desired is merely to be perceived as virtuous rather than truly holding the values they claim - this problem will only be accentuated under a supposedly "public altruism" system). As societies get wealthier, their desires turn toward more generally beneficial things - like having a clean environment, improving the society in which they live, easing the suffering of others, etc., and you can see this reflected in the behavior of affluent peoples of the world (hard to care about the plight of some endangered owl or the theoretical danger to the distant future while you are watching your children starve right now). Maintaining a good reputation, by providing great value for others (socially and economically), is self-interested yet achieves societal benefits. With the dissemination of knowledge about a person's behavior should come social accolades or approbation. The effect of social shunning can be quite powerful, though unfortunately that is often used in very negative ways, as many disagree about what exactly constitutes deplorable behavior. In any significant population, especially one which does not seek to purge diversity of opinion, there will be a wide collection of views as to what constitutes socially beneficial behavior, what approach creates a harmonious future of prosperity for all, whether certain goals themselves constitute improvements to be encouraged or harms to be punished, etc. There is a thin line between enforcing "good" behavior and fascist culture purging undesirables. When you start embracing the hubris of imagining you can design mankind into "better" behavior, be aware of the long history of those altruistic motivations. Never forget that eugenics arose out of altruism - trying to improve humanity as a whole. Colonialism (the "White Man's burden") destroying the primitive cultures of lesser peoples to civilize them and bring Christianity, was largely an altruistic effort. Likewise, there are considerable disagreements about whether gender and sexual minorities should be protected or sent to reeducation facilities for the betterment of society (enforcing the "public good" of heteronormative society)? Should people who hold counter-revolutionary ideas be purged to protect the glorious socialist people's republic from dangerous dissent? Do not ignore these lessons of history if you want something with depth. The world has been improving continually throughout history, and quite dramatically over the past few decades. Greater trade, more social interactions, greater dissemination of knowledge - all of these contribute to substantial worldwide improvements. There are ups and downs, but the trend is clear and strong - it just needs to be allowed to continue. There is no need for creating some special altruism encouragement mechanism (fascist enforcement of right-think), but merely allowing the world to grow more prosperous, more educated, more integrated, and more aware of the consequences of one's actions - the improvement in the world will continue. Sure it comes in 9 steps forward, one step back, but it continues ceaselessly (and the steps backwards generally stem from those with the hubris to imagine they can design the entire world better). Often the best approach is just to do nothing - trust in the emergent order of self-organized systems rather than your ability to design away humanity. Now if you are trying to create a world in a dystopia wherein social engineers have attempted to create the perfect society (just look at the record through history of what happens when that is tried), then manipulating people in the attempt to force altruism is a good approach. If you present a world where this is fait accompli, and post-scarcity utopia has been achieved by "this one simple trick capitalists hate", you will only end up creating a setting which is merely shallow and childishly naive. [Answer] ## Make public service an essential part of being rich and famous Ancient Greek city-states, and even the Roman Empire (at least until somewhere in the late 2nd or early 3rd century) had very little in the way of taxes, essentially only sales tax (only on certain expensive goods such as slaves), customs dues, and a ridiculously low land tax (normally 1%, raised to a "horribly high" 3% in time of war). There was no income tax, no tax on profits and no VAT. And yet millions of tourists come to Greece and Rome to see the splendid remains of a sophisticated civilization. So how were those magnificent temples built, the roads, the aqueducts, the amphiteaters? They were built by rich people for use by the public. The rich, in order to be acknowledged as rich and famous, had to perform [liturgies](https://en.wikipedia.org/wiki/Liturgy_(ancient_Greece)), that is, literally, public works. Liturgies proper were legally enforced; once the Hellenistic world became rich, after the days of Alexander the Great, the legal obligations fell into disuse, and [evergetism](https://en.wikipedia.org/wiki/Euergetism) (literally, doing good deeds) became purely socially expected. (This is what the Romans inherited; they never had a legally enforceable obligation for the rich to contribute to the society: it was simply the expected behavior.) What the rich got back was immortal fame. How many millions come to Rome each year to see the [Pantheon](https://en.wikipedia.org/wiki/Pantheon,_Rome)? And there it is on the frontispiece, perfectly readable after more than twenty centuries: M. Agrippa L. F. Cos. Tertium Fecit -- [Marcus Agrippa](https://en.wikipedia.org/wiki/Marcus_Vipsanius_Agrippa), son of Lucius, third time consul, made this. (Of Agrippa's Pantheon only the façade survives; the marvellous concrete monolith was built in the 2nd century under Trajan and Hadrian). And so the [Gardens of Lucullus](https://en.wikipedia.org/wiki/Gardens_of_Lucullus), the [Flavian Amphitheater](https://en.wikipedia.org/wiki/Colosseum) (better known today as the Colosseum), [Trajan's Forum](https://en.wikipedia.org/wiki/Trajan%27s_Forum) and, not least, the [Appian Way](https://en.wikipedia.org/wiki/Appian_Way) "the queen of long roads", begun by [Appius Claudius the Blind](https://en.wikipedia.org/wiki/Appius_Claudius_Caecus) towards the end of the 4th century before the common era. In the classical world, good fame was the supreme good, and wealth was but a means to achieve it: this is the entire secret. > > Omnis homines, qui sese student praestare ceteris animalibus, summa ope niti decet, ne vitam silentio transeant veluti pecora, quae natura prona atque ventri oboedientia finxit. > > > All men, who desire to distinguish themselves from other living creatures, ought to strive with the utmost effort, lest they pass their lives in obscurity like beasts of burden, which nature has fashioned stooping and servile to their belly. > > > (C. Sallustius Crispus, On the conspiracy of Catilina, English translation by Rev. John Selby Watson, M.A., 1899, at [Perseus](http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3atext%3a1999.02.0124)). > > > We note that some rich people have continued to strive to live to this ancient ideal, and even in our corrupt days some still do; for example, the [Bodleian Library](https://en.wikipedia.org/wiki/Bodleian_Library), funded in the late 16th century by [Sir Thomas Bodley](https://en.wikipedia.org/wiki/Thomas_Bodley), or, in our present time, the [Gates Foundation](https://en.wikipedia.org/wiki/Bill_%26_Melinda_Gates_Foundation) or even the [Tesla](https://en.wikipedia.org/wiki/Tesla,_Inc.) and [SpaceX](https://en.wikipedia.org/wiki/SpaceX) companies into which Elon Musk sunk his PayPal fortune. But it is no longer the norm. It should be. [Answer] # Star Trek Replicator A key point in this utopian future is the retiring of scarcity. It probably will come first or along side the social changes that TheSexyMenhir and AngelPray are talking about, not after, but if I don't have to want for anything at all (I don't need money, or food, or stuff cause I can have it all at the push of a button - and I don't have to work for anything at all). This leads to people only doing things because they enjoy them. It is a hard thing to truly wrap your mind around because scarcity is ingrained. The important thing would be that the replicator technology be open sourced, and available to everyone and the government and culture to support it. Right now we have gotten pieces of this to work eg the internet has removed the information barrier, so information is now nearly free(there are government laws protecting special interests like music, these would have to go away). We also aren't terribly far from automation and renewable energy reducing the cost of producing everything to nearly zero. If we then can use education to greatly reverse the population issues of our world, and/or settle other planets to spread us out so that land is not scarce, we might find ourselves looking at just having to figure out how to get along ideologically and we will be there. [Answer] I don't think it's possible to exhaustively answer this question in a book, not to speak of a post on Stack Exchange, but let's try to find some starting points. The system and society we live in is based not only on historical developments but also on a broad range of incentives and natural tendencies and motivations. Trying to find key points in those may be a good start. Obviously this is heavily influenced by my personal opinions on things. Here's a few: ## Humans like to feel powerful Bullying is a way to exert power over others. The most important reason to do so is generally a personal need to feel powerful. This need often stems from a feeling of powerlessness which needs to be compensated. That's not to say that some people won't try to exert power and get drunk on the feeling, but many crimes of power are specifically committed by those who don't feel that they can validate themselves in other ways. This doesn't just include bullying but also many instances of rape, child abuse and domestic violence. Because of this, first and foremost it's important to let people grow up and live with a feeling of agency over their own lives. Those who feel victimised, treated unfairly and believe they have no power to choose or influence how their life goes aren't only worse at trying to better themselves but also the most likely to lash out in order to make themselves feel better. Giving a feeling of agency is hard. It influences childrearing, it influences school systems to a large degree and it's also connected to things like mechanical, boring and ungrateful work (see also Marx's theory of alienation). It's further influenced by inborn advantages and disadvantages such as disabilities. And lastly, it's heavily connected to expectations which are themselves in flux and can devolve into entitlement (see also my third point). Another point is that we tend to internalise abuse and will sometimes perpetuate it, project it outward onto those we either feel have it better, remind us of our abusers, remind us of ourselves as we were being abused etc. We will often try to defend our abusers, especially in childhood and romantic relationships, and thus convince ourselves that the abuse is loving or even deserved. Then of course, we may later abuse those who we love and believe deserve it. We do this because we don't want to believe someone we love would harm us, because we don't want to admit we are damaged in some way (because that makes us feel weak) and because of many other sad reasons. I personally would expect a society based on secular humanism to outlaw all kinds of corporal punishment for a start, but else I don't have much of a solution to this except for a well funded universal mental healthcare system. In any case though there should be a wide awareness that the need to put down others reflects on one's own weakness. ## Humans are only satisfied by things getting better It isn't generally part of human nature to be content with a situation, even a relatively positive one. Humans constantly strive for improvement. We're naturally predisposed to recalibrate our measure of "happiness" and "suffering" according to our experiences, which lets us adapt to things like disabilities caused by accidents, but it also means any accomplishments and comforts we have will over time become an expected standard instead of a boon to us. We will begin to feel entitled to these things and while their loss will cause us suffering, we won't feel happier for having them. Our expectations may get out of control. There are philosophies that emphasise appreciating what we have and curbing excessive desire, but those are limiters on the natural tendency which still exists and doesn't go away. Your society should encourage the attitude of being mindful of the things people possess/receive while trying to focus a person's need for improvement onto their own ability and understanding rather than their living situation - which however needs to be a decent one to begin with. ## Modern society is too big for certain social mechanisms A lot of the social regulation that works well with inherent human moral tendencies only works on the level of a small group - tribe sized. Masses are anonymous and thus we don't feel as bad if they're suffering or if we are doing something to harm them. Personal reciprocation, punishments like shunning and mechanisms like reputation all lose power in a faceless mass of billions. Our own instincts of empathy are numb towards large numbers, which is why both in advertising, asking for donations and in storytelling we tend to focus on individual characters instead. I don't know what to do about this, but I know what not to do: segregate. In our society, rich people live in their own closed communities which are essentially a different world altogether. Their children often go to expensive private schools and some have no understanding at all of scarcity or poverty. Religions tend to do the same, and we've long known that people who have GSRM friends are less discriminatory towards the group as a whole. So your society needs to ensure regular social contact between all layers of society and may also encourage learning languages and travelling. ## Capitalism has a natural feedback loop towards inequality Capitalism can improve the overall wealth of a society (and has to a degree done so in the past) but it also will concentrate the wealth in the hands of the few and this will progressively get worse. Just like a first past the post voting system will inevitably lead to a two party system, this too can be shown mathematically - at least on a basic level. Unfortunately it is difficult to replace personal wealth as a motivator. For this, many solutions have been proposed but very few have ever been tested. A credit economy in which money can be spent but not amassed (e.g. parecon), a sandbox market for entrepreneurial activity, a form of a participatory planning economy or just maybe some kind of social capitalism, possibly all with an unconditional basic income? We just don't know enough about how these things work in practice to say which is best, so you can choose whatever you like most. What we can say is that unregulated capitalism and authoritarian socialism generally haven't worked well whenever we tried them out. I'm a libertarian socialist, so my thoughts go in certain directions, feel free to go wherever else with yours. ## Humans want to give their own offspring an advantage One of the most difficult things about trying to achieve a level playing field in regardless whatever kind of economical system you have is that parents will want to pass on their earnings to their children. This includes both education and material possession. Providing for one's children is a deep rooted human trait and originally a very positive one. It can however easily lead to an increase of inequality as generations progressively build on their advantages, leaving less lucky ones behind. The only solution to this that I know of is to encourage this behaviour on the educational front while limiting the private ownership of material advantage far enough that passing on what can be owned doesn't cause too much of a problem. ## Justice works differently from how it feels Personal and systemic are two very different categories. For example, I don't think that the death penalty should exist, but there are still people who I'd gladly murder if I could get away with it, because I think they deserve to die. We humans like the idea of revenge, we become obsessed with it. However, retributive justice isn't a particularly effective system on a societal level, the attempts at reform we make are in many cases token efforts and there are incentives against reintegration in many countries. I don't know of a way to curb the human desire for revenge, but we are absolutely able of using a system that doesn't succumb to it. Let your society use a system focused on restorative justice wherever possible and use incarceration as a tool of crime prevention by segregating those who're a danger to others. There's a lot of untested ideas to play with here. You could, for example, try the Australian approach of putting serious criminals into their own separate society in which they're allowed to live freely as normal, only they can't leave without permission. It's not a system I'd use in reality, but it makes for interesting stories. I would also consider nonabusive forms of prison labour. More importantly though you should minimize imprisonment altogether and reserve it for violent criminals mostly. Focus instead on making amends to victims, placing offenders under supervision, loss of certain rights and privileges such as access to certain jobs (in which they'd have the potential to do lots of damage). Lastly, you'd need a court system that deemphasises the nature of the criminal and emphasises the facts of the case, evidence and clear guidelines for convictions and consequences. Jury systems have the unfortunate trait of people being easily swayed by emotional appeals and personal prejudice. ## A political caste can be problematic In almost every society I know of we will at some point have people who're specialised politicians. The problem with this is that a) this again leads to a form of segregation with those in power not being affected as much by their decisions as others and b) the ability to convince people to vote for you isn't necessarily correlated with the ability to govern well (see also Trump). The thing is, both a functioning representative democracy and most forms of participatory political systems (say, council communism) have the same problem and that's education. Uneducated people will easily vote for demagogues against their own personal best interest, because they make uninformed decisions. Uneducated people also probably won't make good decisions in a direct democracy for pretty much the same reasons. And I'm reluctant to propose some kind of expert oligarchy for obvious reasons. Direct democracy also has a problem of taking up lost of time, i.e. inefficiency. If we allow ourselves some kind of utopian fiction we might go for a form of digital democracy in which the internet is used to much more quickly inform people and let them cast their votes, but well you've seen what the internet is like now (see also Breitbart). I honestly have no idea how to ever solve this conundrum, although better political and economical education as well as bringing back rhetorics as a subject would be a start. (...) Sorry but I need to stop here even though this is far from complete. Maybe I'll add more later, until the I hope it's helpful and I apologise to anyone who feels offended by my radical leftist propaganda. EDIT: Sorry this took so long, but I really wanted to quote an excerpt from a book here and then I couldn't find my copy of the book. We'll have to do without. For what it's worth I heartily recommend giving Nick Harkaway's 2008 novel "The Gone-Away World" a read. ## Inhumanity of nonhuman entities Organisations aren't human, and despite what someone may have decided about Hobby Lobby, they don't really have beliefs and feelings either. But they do have structures, and they do have goals, and their structures will be built to serve those goals. One of these goals is self-preservation. When we look at churches, corporations or ideologies, they are human constructs of varying generations. Religions are human constructs, memes essentially. They survive in a world of memetic natural selection by adopting traits that support their survival, for example making doubt a sin and blind faith a virtue to dissuade people from thinking too hard about why they don't make sense. Churches then are constructed to serve the religions, but a church in and of itself has structures and goals of its own. And even when we assume that in the beginning an idea was created in order to benefit mankind, just like certain religious ceremonies were created for a rational purpose that doesn't exist anymore but have been retained as ritual nonetheless, ideas and organisations can become corrupted by choosing to protect themselves rather than the reasons why they were created (see also the catholic church child rape scandal for an organisation trying to protect itself above everything else). The thing is: organisations don't have human empathy or common sense. They will go after their goals single-mindedly, only tempered by the humans in them that have the power to decide humanly. But since these human aspects will generally go against these interest of the company as a whole, the development will always go against it. A private corporation's goals is profit. And thus it will internally select for the more ruthless leadership, the lower wage, the higher price and the dirtier methods as long as those serve this goal. This has a dehumanising aspect on its members who're incentivised to become less human to advance and get all the other nice things that humans want like the feeling of power from my first point and also lots of money. They will justify their behaviour to themselves, they will compartmentalise their feelings like an Auschwitz guard who's a really loving family man at home, and at some point they will hit their bottom line and be replaced by someone who's willing to sink lower for the cause. This is how utopias turn into dystopias. [Answer] You have a personal bias as to how interpersonal interactions should occur, and how society should be organized. It comes across in how you describe bullies, and bully POVs. This is not criticism, it's purely an observation. Unfortunately your ideals run completely parallel to human nature. Mankind may one day reach a point where scarcity is a thing of the past. I sincerely doubt it, but it's not entirely impossible. However, even at that point, human nature will still come into play as far as societal and inter-personal relationships are concerned. Human history is full of conflict, murder, and strife. This is not a coincidence. For hundreds of thousands of years we fought for survival, and this can't be changed merely because, ideally, we should all get along. Even if a majority of people agreed with that sentiment, human society is not monolithic. There exist thousands of cultures on this planet, and if one embraces pacifism to a great degree, then some other more aggressive group will simply conquer them. For a society to be successful, the state has to protect its citizens interests, and sadly this sometimes means that some other group will have to suffer in order for yours to thrive. And realize, that existing in a post-scarcity society will not help eliminate conflict. People don't always fight over food, or resources. More often than not they slaughter each other for ideological beliefs. And so, if your post-scarcity society is super friendly, and inclusive, but another society is very driven by ideological belief, then they will either infiltrate your own system and use your acceptance against you, or they will outright attack and conquer you. [Answer] By introducing a set of rules which determine what is selfless and assigning punishment and rewards according to those rules. You know, like laws. Okay, almost like laws, but for everyone instead of only for those that are too poor to defend themselves with smear-campaigns, expensive lawyers, and bribes. --- Implement the following changes: * Unified World Government and unified legal system. => No sanctuaries for those that break the law. Takes away a common threat of corporate lobbyists; "If you do this, we'll take our business (and tax-money) elsewhere." * Destroy Monopolies => You need to prevent any one power to be too powerfull to be regulated by your laws. * Prevent Cults of Personality from Forming => Again, you don't want too much power in one hand. The End goal of the above points, is to create a society where anyone can feel that the law is applied fairly (assuming the law is actually fair). This will make those governed by those law more likely to act according to your laws. It's very important, that the people will WANT to follow your laws. That way they can be absorbed into the cultural consciousness - and with time can become habits. [Answer] You might be looking for a [gift economy](https://en.wikipedia.org/wiki/Gift_economy). It's not uncommon in some societies, though it's been mostly eclipsed by market-driven economies. Modern western societies try to move in that direction occasionally, with governments gaining prestige according to how many people they 'help' through social programs, but, to fuel that, they have to aggressively tax other people. Perhaps you could model it in a modern feudal society, where different strata are expected to gift up and down in different ways. [Answer] This helps explain why actually evolution does tend to prefer niceness: <https://www.psychologytoday.com/blog/evolution-the-self/201607/the-prisoner-s-dilemma-and-the-virtues-tit-tat> The point is that the ideal behavior for an individual is to initial be nice but get revenge when they are wronged, to prevent others from further wronging you. It actually explains a lot of human behavior. But perhaps if when others wrong you, not only do you get revenge but others in the group will work together to get revenge in some way that sterilizes you.. possibly including death or long jail time, which in a sense does happen. Or perhaps others could do something to reward nice behavior.. which encourages more of it. So sort of a tit-for-tat for niceness as well. Which also sort of already exists. But the point is if either of those was in some way taken to the extreme, evolution would favor the selfless. Or what about this? They evolve the ability to detect when each other are lying? That might be just enough to strengthen tit for tat for both positive and negative behavior reinforcement. [Answer] Promoting selflessness is a mistake, even if that is what you want. An easy analogy to explain this is in the topic of Business Profits. In business, it is a big tactical mistake to focus on profits and keep trying to think of ways to make more profit. This kills more successful businesses than any other tactic. This does not mean one shouldn't be aware about profits, they cannot be ignored: But it is important to realize that profits are a residue, what is left over from customer payments after satisfying the customers. The point of the business is to satisfy customers at less cost than the customers will happily pay. The distinction seems trivial, but there are MANY easy ways to increase profits by making customers less happy: less choice, less service, less quality with cheaper parts, less guarantee, a worse return policy, and so on. It is very difficult to make more profit and keep the customers equally happy. Most businesses have already minimized their staff and other expenses, so to make a bigger profit they turn to shortcuts, and lower quality (sometimes by overburdening their work force, which grows stressed and resentful and less attentive to the quality of their work). The cost-cutting approach can work for many years, but eventually the drip, drip, drip of customers leaving (along with their best employees, because those are the ones that can easily find easier jobs) puts them in a financial bind, and the lost customers and good employees seldom come back: They have found something they like better. It is more difficult but usually possible to make customers more happy, with a small increase in price and a smaller increase in costs, and thus take home more profit. Or if you have happy customers, to work on marketing to get more happy customers without changing quality. So back to the selfless! You have a similar problem here; selflessness is, like profit, a residue. It emerges naturally from human nature when their own self feels satisfied: sheltered, healthy, safe, secure, socially connected and free to help. Or not. They do not have to feel rich. We have a lot of people in this position in the world: Retirees in countries where they receive a secure stipend they do not have to work for, along with health care they don't have to work for. Many of them donate time and energy to various causes. I would warn that numerous psychology experiments show that rewarding somebody for any act (which includes selfless behavior) tends to make them think transactionally. In particular this includes behavior they did for free (like painting, or playing a game) because it was fun: If they start getting paid for it, even \$1, they tend to no longer do it for fun: They expect a dollar, and doing it for free is no longer fun because it isn't rewarded! This is true for both children and adults. The answer is, if you want to promote selflessness, you should do that indirectly by promoting the kinds of conditions that eliminate the barriers to selflessness most people have. What are those? Trying to make sure they don't end up homeless, trying to make sure their kids are clothed, fed, educated and have healthcare, trying to make sure their own retirement is not going to be a stressful hellscape at the very time their physical and mental capacities are on the decline, and their health costs are increasing. Now it sounds like I am advocating for socialism, but I am really not (at least not the socialism most people think of). The point isn't to make all of society equal, or equally rich. The point is not to put a ceiling on anybody; the point is to put a very substantial floor on how far one can decline financially: That floor is you will always have enough to not go hungry, enough shelter and warmth/cooling, water and sewage services, enough safety to be seldom worried about victimization by criminals, enough healthcare to not worry about suffering for lack of care, and enough education for your children to not worry if they will be able to make it in life. If you promote that, selflessness will be maximized automatically. ### Added to address OP commentary. Social status will always matter; that is human nature. Power does not always matter. I provide a specific circumstance, in the hope you can generalize to the broader culture: At the university I had dozens of friends I got together with in various combinations, but none of us were ever "in charge" or deciding what we will do, where to eat, what volunteer projects to join, etc. New professors and college workers were often invited along, usually to lunch or a presentation or whatever. They could become our friends and be part of our informal group. But we would quickly disinvite and rebuff any that insist upon trying to be "the leader". We don't want leaders, even our department head was elected by us and could be un-elected and replaced. We want colleagues, companions, and people with a sense of humor, and the same goes for collaborators on our scientific projects: Nobody wants to spend two or three years of their life working alongside a jerk that is constantly trying to assert they are in charge and always knows best. That is the part of the point of having a social connection first; to see if people can go along with somebody else's idea, even if it just Thai food for lunch instead of Pizza. They don't have to like it or pretend they did, but if they can't shrug off a minor mistake and all they do is complain about how Pizza would have been better --- In our culture, that personality trait goes beyond lunch and makes them a solo researcher in their career. The same would go for trying to insist upon a place for lunch: If Richard asks me if I feel like Thai because he knows I like it, and we invite newbie Samuel along with us and he doesn't like Thai, he can decline without penalty. If he wants burgers, we will say we are set on Thai, if he tries to insist we should try his burger joint, we still refuse and again, that attitude of not taking "No" for an answer, if persistent and repeated, will result in academic isolation. Now to apply that to your culture at large: In a post-scarcity society (a mini-version of that is approximated by academics and researchers working in a university setting), the notion of Project Leaders is acceptable and often an organizational necessity. Somebody has to pay attention to coordination and project-wide decisions, funding, schedules, progress and information dissemination. But Power over others does not have to come with that; such power (for example to fire somebody, hire a person or firm to do something, spend large sums of money, or rewrite the budget) can be reserved to various committees by majority vote. What makes people act selflessly, even if they are not inclined to do so, is a culture that rewards them with friends and collaborators for what they care about; and the punishment of isolation if they show a pattern of acting selfishly or trying to gain power: No friends, no colleagues, no collaborators. This is not a monetary reward or punishment, but even more effective than that. The post-scarcity part is very important here: The strong safety net means nobody must work for anybody, so they don't work for people they do not like, or regard as selfish power-mad jerks. IRL that type of person gets away with their behavior because so many of their employees feel trapped in the job and forced to put up with a boss they dislike, or even hate. With a strong safety net, young adults won't tolerate such behavior: They in particular have little to lose (in terms of lifestyle) by quitting and falling into that safety net, so they just won't take jobs (or stay in them) if their boss is overly controlling or doesn't treat them fairly. That in turn means very few such people ever get to be bosses, because their turnover rate is too high, constantly incurring new training costs and learning curve, which is too expensive for their bosses to remain competitive. That is cultural feedback: Bosses need approval and friendship of their subordinates, and that same personality trait has to eventually travel up to the top of the pyramid; because nobody on the bottom layer of the pyramid (our minimum wage slots) has to put up with any shit and can walk out at any time with zero consequences in terms of their lifestyle. About 97% of people want to have friends, and the big, society-wide projects that bring high social status require teamwork. You can't make an action movie alone, you can't build the Large Hadron Collider alone. You can't even build much of a business alone, if the culture of working with friends that share equally means few people want to work for you! Of course one can write a novel, or a song, or a mathematics paper alone, but for most life is more enjoyable with friends and co-workers, and that is also the route to getting bigger projects done that carry more social status. It is nice to be a part of something, and held in high regard by your friends. If much of that regard demands you be a good team player and selfless, then that is what you do. [Answer] To answer how an altruistic society might evolve, look at what caused it to evolve to be the way it is now. Most of human history there was scarcity of food and a lot of danger from predators or other human tribes competing for food, so physical strength and ability to amass resources were very important for survival or the group, so such people were viewed positively by society. In the modern world fighting off bears is less of a concern, and a much bigger problem might be environmental collapse. If you extrapolate that further, you could say that in few short thousands of years (or hundreds if you want to be optimistic), humans will evolve to dislike greed, due to it's wastefulness and environmental concerns, while emphasising non-violent cooperation, since efficient use of resources is more important then fighting off things. Eventually creativity, ability to get along and not-hoarding things might become more socially desired then strength and wealth. Also robots will do all the heavy lifting so who needs strength, am I right? [Answer] I think the question may be slightly different than you are thinking. You are asking for help to build a selfless utopia. I would argue the challenge is not finding a way to build a selfless utopia, but to pick one from the thousands that have come before us. What you seek is a very popular topic in philosophy. Hundreds of philosophers have penned their words on the topic, trying to capture that fundamental essence that makes us better. The hard part is not standing up on a soap box and proclaiming my vision for society. Instead, I think it's more effective to proclaim that of others. There are some really good ideas out there in philosophy, if you just research them. Arne Naess championed the idea of the Ecological Self through most of the 20th century. He coined the term, defining as "The ecological self is that which the self relates to." He wrote a great number of articles arguing that this definition of self is no less meaningful than any other definition, while its implications are vast. For example, he solves the issue of the selfish gene in this way: altruism is really selfishness in disguise. He argues that Mother Theresa was the most selfish person who lived, but the self that she associated with was so wide and all-encompassing that it was possible to misconstrue her wide selfish behavior as mere altruism. According to Naess, she did what she did not because she loved the children she helped more than she loved herself; she did it because she loved herself in such a wide and rich way that we are all better people for the time she spent with us. If such a philosophy were common place, I think the world would have a different color today. Or take the works of Alan Watts. He teaches a different argument, one that is more Eastern. Instead of arguing that the self is vast, he argues it is small, and perhaps even an illusion. What remains without that illusion is... well... it's something else. The hard part with paraphrasing such philosophers is that their ideas deserve more credit than one can truly give in a paragraph. Instead, if I may link a [video](https://www.youtube.com/watch?v=qHnIJeE3LAI) which has some of my favorite (and more accessible) ideas he's put forth. I highly recommend giving him the attention he's due if you're writing of a world for the selfless. In reality, the hardest part I have found, when it comes to such a topic, is that the people who are truly striving for this sort of society aren't the ones talking about it. They're the ones who are too busy doing it. But if you go looking, you'll find more than enough gurus and sifus and pastors and mentors, each with a little piece of the puzzle to unlock the society you seek to write about. So enjoy! Namaste! [Answer] Essentially this would take a major cultural shift. Considering our world will be dealing with major changes in the coming century. Rising population, dwindling resources, the shift to renewable energy, the necessicity for recycling of resources, global warming, multipolar geopolitics, displacement of people from the workforce with robotics, and a rebalancing of culture and political power away from the European nations (and, yes, the USA is a European nation) to the non-Western. It is possible that probable there will be cultural, social, economic, and political realignment on a grand scale. In circumstances like these, precisely the kind of cultural shift to much more selfless society could arise. There is, of course, no guarantee this could be the outcome, but if a plenitude of factors happened to fall out the right way, then it might be possible. [Answer] In contrast to the other answers I think it is quite possible, but it would mean a radical approach. You may not like this at all, but if you want more and more good people, you need to inhibit procreation of bad people to suppress genetic inheritance and you need to inhibit bad upbringing to suppress psychological damage. There is no other way. At first I would say we are in fact on the right track so far: Despite the sensational approach of newspapers and TV and a flood of horror movies depicting a world of violence, if we compare the track record, the number of violent crimes has steadily decreased during human existence. Also the number and extent of wars and its casualties in comparison to their number of citizens has decreased (As horrific as WWI and WWII were, they inflicted less proportional casualties than the earlier Thirty Years war!). Also the casualties were caused by the progress of conventional weaponry. I think we have currently the situation (from my experience, totally unscientific of course) that some people strive for good actions, less people strive for evil and selfish actions and the rest of the population are opportunists which adapt to the situation. What advantage have good people? They can work together, trust each other and they are able to hold out bad situations if the need arises. Bad people on the contrary have always the problem that they must always look out for other bad people that can deprive them of their earnings or fool them. So the standard approach is the bad people are looking out for good people which can be exploited. Knowing that after a time victims know their identify, perpetrators are often moving to a new home. So the solution is simple: Good people are taking the next step of networking together (the idea itself is old, see freemasonry) and use the current technology to allow each good person to collect and identify predators. Every time a good person is taken advantage of, every good person ceases to support the perpetrator or people who support him/her. This is not done by shitstorms or actively harming them by violence etc., but by passive resistance. You do not listen to their schemes, you do not buy something from them and you do not sell something if you are not legally obliged (shop owner). The perpetrator hits an invisible wall. The next step is political organization. The good people are electing their best trusted person for political power. Now the question hangs on the fact if the majority of opportunists will choose a party which in fact tries to hold promises and which can be trusted (I am not sure of that, short-sighted decisions are unfortunately often popular). Having not the option of the typically evil actions of killing and castration to inhibit procreation (we are still talking about people supposed to be good), the only way I see is that people who commit crimes are redlisted. Redlisting means that people are informed that they are not suitable partners and if this fails (humans are dumb), the redlisted people will go to prison if they procreate and their childs are free for adoption. The prison surely does not circumvent people to have a first child, but it puts them out of the way for further procreation. The goal is not total control, but stacking the deck for good behavior so that after generations Darwin can do the work. Also people who are visibly overburdened with rearing up a child (which is a common occurrence now) must get counseling to avoid losing their childs (to inhibit the environmental component for bad children). This is the thing where people will balk at because it means we are abandoning the notion that people have a right to procreate and it strongly reminds us of the eugenics motion during the first half of the 20th century. As this is worldbuilding, I am telling you an option which you personally may despise. On the other hand: Few people do not accept that we inhibit possible dangerous behavior by e.g. a driving license which prohibit problematic drivers and drug users from driving. But everyone should be allowed to rear up a child which can be abused and mistreated? [Answer] My first exposure to a post-wealth economy was "...And Then There Were None" by Eric Frank Russell, later reprinted as part of his novel [The Great Explosion](https://en.wikipedia.org/wiki/The_Great_Explosion). That society had developed what some people refer to as a moneyless gift economy, where social disapproval was the medium of economic enforcement. With more mature eyes I don't think the principles involved would scale, but certainly things like [potlatch](https://en.wikipedia.org/wiki/Potlatch) (a simple form of socialism where tribes competed to give away wealth for status) could grow in the right soil. [Answer] If you want society to become selfless, you have to construct your world so that selfish behavior is consistently more self-destructive than selfless behavior, and furthermore this difference must be a natural consequence of action, and not a indirect consequence via rewards and punishments bestowed by whoever is in charge. The stick-and-carrot approach fails because people will readily grasp that their selfish behavior led to their suffering only because you disapproved of it and applied a punishment. A lot of the behavior that is called "selfish" in regimes seeking utopia is really nothing more than people objecting to getting screwed over by the latest five-year plan. Furthermore, in order to effectively deliver these slaps and benefits you will need to concentrate a great deal of power in your hands. This will inspire the greed of those who want that power for the wrong reasons, and you will be playing Snowball to their Napoleon. [Answer] # Survival of the Most Co-operative It's actually the natural order of things. A culture of any beings (not just humans) dominated by constricted/ selfish attitudes will most likely die out. Google the phrase "survival of the most co(-)operative" for articles such as <https://www.positive.news/2014/economics/14547/compassionate-survive/> with deeper links to scientific work. It is our scarcity economy, our culture (self-made concepts) that are at odds with this order; not the other way around. You could have a crisis moment, after which the -only- survival choice is a more co-operative system. Or you could have evolution play its path (albeit one with Fermi-Paradox-like near-misses regarding self-extinction). I'm sure there are other options. As a species we have a natural 'background fear' which comes from several things. Harari in his (dubious, imho) latest book 'Sapiens' puts that down to humanity cheating to get to the top of the jungle heap. I'm not sure it's just that. Ego evolved to preserve the vital prerogative to persist. In nature that was useful, but it became too strong. Putting these threads together, our challenge is psychological; not ideological. We do need better myths. But I doubt it's a philosophical question, as others have said for their own reasons. Something to change our psychological priorities, reduce our egotism, or get us staring down the barrel of extinction might do it. Might. I'd like to think meditation might contribute to that psychological shift from ego. But I can see that being controversial on this site. [Answer] I'd strongly urge you to look to [Game Theory](https://en.wikipedia.org/wiki/Game_theory), [minimax](https://en.wikipedia.org/wiki/Minimax), and the rational strategy as opposed to the [superrational strategy](https://en.wikipedia.org/wiki/Superrationality). Nash proves that cooperative behavior is mathematically optimal by analyzing minimax equilibria. In normal Prisoner's Dilemma, the rational strategy is to defect, to guarantee minimal downside, but the result, if the other agent also rationally defects, is less benefit for both participants. The superrational strategy, where both players cooperate, leads to the maximum benefit. (This is problematic in un-iterated Dilemma, but it's easy to prove that persistent defection in iterated Dilemma with a superrational agent is irrational.) Financialists don't like Nash and his ideas because it undermines the license they have to wreak havoc on the economy by pursuing self-interested goals with no concern for the fallout. Financialists, which is to say people who make their money by speculating, have more incentive to exploit [Pareto Efficiency](https://en.wikipedia.org/wiki/Pareto_efficiency), which is gain that requires making someone else worse off, because the markets are filled with optimists (otherwise known as "[marks](https://en.wikipedia.org/wiki/Confidence_trick)") with less information and resources than the financialists, who can often drive the market. Pareto Improvement, under which a party or parties may benefit without making someone else worse off, is the ideal for for a society that values humanity, and produces maximum benefit for that society. The best part is, this position is not subjective, but arises out of the mathematical analysis of equilibria in the framework of Game Theory. [Answer] If it didn't already exist, I would be suggesting our current system! By which I mean the combination of capitalism and socialism typically observed in "western" countries. The idea being that people that contribute to society are rewarded with money which they can use to buy what they want. There are people out there building our buildings, making cars, clothes, food, technology, etc. for the benefit of society. Sure they are not "selfless" because they are only doing it for the money they'll get in return, but it achieves the desired effect to a certain degree. Anyway, to "favour" the selfless leads to a contradiction because if they are being selfless because it favours them to be so, then they are not truly selfless and therefore it's no different from the "do work in exchange for money" proposition that the capitalist system offers. (Then we add a dash of socialism to prevent exploitation of workers, pay for things which are needed but no one in particular would pay for (e.g. the police) and help people who have difficulty paying for the benefits they require) It's far from perfect and incredibly open to exploitation, of course, but like any suggestion you'll find on here, "in theory" it works. In terms of your requirement to "individuals prefer the long-term profit for all to the short-term profit for one" - this may not be the goal of the individual, but it is the intended outcome of the system as a whole. It also tries to "demotivate the bully" because, of course, we have laws and punishments. ]
[Question] [ If the Earth was destroyed by a cataclysmic event such as a large mass colliding with it, such that it fractured into multiple pieces, would any trace of human civilisation remain intact ? I.e., if some alien race discovered the remnants and thoroughly examined them, would they find anything that would suggest that a civilisation once existed on that world? If so, would these traces include substantial things like buildings or structures remaining intact on pieces of the fractured earth? [Answer] ## Artifacts on the Moon Even if Earth's surface will be completely cleaned, there is a chance that alien scientists would notice some signs of civilization [left on the Moon](https://en.m.wikipedia.org/wiki/List_of_artificial_objects_on_the_Moon) or a near planet. If the catastrophe was not big enogh to disrupt Earth gravitation field it is also possible that some of [more than 3000 satellites](http://talkingpointsmemo.com/idealab/satellites-earth-orbit) will be still orbiting the planet. [Answer] # Small traces, nothing big An impact like that would not "fracture" the Earth, it would "splat" it, like if you shot a big drop of water with a BB gun. On large scales like that, there is nothing that is "solid"; everything behaves like fluid or putty. You cannot even drill 10 kilometer down into the "solid" crust of the Earth without the bedrock closing in on the hole as if it was a malleable material being squeezed. With an event like that, every place on Earth will have an earthquake that is entirely off the scales. The crust of the Earth will ripple and flex in completely unimaginable ways. This will shatter any and all man-made structures. And even if you would get some really large chunks, these will eventually crumble under their own gravity and form new spheroids. Nothing will remain standing because the very ground we stand everything on will have shaken so violently that no structure will remain intact. That said... Even a pile of rubble is a trace. If your aliens' scientists are worth their salt, they will notice very curious distributions of materials. There will be billions of blotches and spots all over the place where they find concentrations of compounds that just cannot form on their own. The one thing that can stop this is if the partitioning is so violent that the extremely thin crust that we live on gets crushed, blended and mixed into the hot contents of the rest of the planet as the chunks collapse under their own gravity. Unfortunately — for you — it is not at all unlikely that this is exactly what will happen. [Answer] # The Earth won't fracture Any impact large enough to 'fracture' the Earth, would first melt it. For example, the [impact that made the moon](https://en.wikipedia.org/wiki/Giant-impact_hypothesis) likely liquefied the entire crust. In that case, there will be nothing identifiable on the Earth. Other answers mention this that and the other thing that might be recognizable; but liquefaction and a vigorous stirring (since there is no other way to describe being hit with a moon sized object at 4 km/s) would mix all evidence of humanity in with quintillions of tons of water and rock and mantle until nothing could be identified, with one exception mentioned below. # Things not on Earth might remain. Another comment points out that the liquefaction of Earth would likely not leave much standing on the near side of the moon. However, there are a few probes lost in the vast-ness of deep space, and some broken-down rovers on Mars that will be there for some time. Not that long, in the case of Mars, due to the dust storms. # Isotopes would be the only identifier While you could not identify a layer of activity to associate with an 'Anthropocene', given the vigorous mixing mentioned above, alien geologists would know something was up. We humans have made non-trivial amounts of some elements that should not be there. The [fission yield curve](https://en.wikipedia.org/wiki/Fission_product_yield#/media/File:ThermalFissionYield.svg) shows what nuclear wastes are produced in what relative abundances. Of the seven [long lived fission products](https://en.wikipedia.org/wiki/Long-lived_fission_product#The_7_long-lived_fission_products) in nuclear waste, Technetium-99, Cesium-135, and Zirconium-93 are each relatively common. Alien geologists, assuming they showed up in the next 1-5 million years, would wonder where all these unexpected isotopes on an otherwise barren world came from. Or maybe they won't wonder because they are Daleks and they sent the planet-liquidizer. [Answer] It strongly depends on which level of details they can examine the sample. There are many traces that indirectly point to a civilazation. * an abnormal concentration of metals in a rock can suggest that the rock was a metallurgic debris, implying that some civilization extracted metals from ores. * polimeric materials (yep, plastics) or glasses can also point to an evoluted race capable of manipulating materials (no PVC, TFE or borosilicate glass is naturally formed, afaik) So these traces would suggest that a civilization existed. Large structures would remain, again, not as big thing (no Coliseum or Big Ben for them to look at), but as a distinct chemical trace ( a skyscraper would maybe leave a lump of molten steel derived from its supporting frame, together with methamorphic rocks originated from the concrete and building stones) [Answer] # Yes, but you would need astrogeologists to study the remains. Sufficiently advanced civilizations leave a geological record. Let me quote from [Anthropocene (Wikipedia)](https://en.wikipedia.org/wiki/Anthropocene): > > The Anthropocene has no agreed start-date, but one proposal, based on atmospheric evidence, is to fix the start with the Industrial Revolution (late eighteenth century) > > > [...] > > > Fossil record > > > Increases in erosion due to farming and other operations will be reflected by changes in sediment composition and increases in deposition rates elsewhere. > > > [...] > > > Trace elements > > > In terms of trace elements, there are distinct signatures left by modern societies. For example, in the Upper Fremont Glacier in Wyoming, there is a layer of chlorine present in ice cores from 1960s atomic weapon testing programs, as well as a layer of mercury associated with coal plants in the 1980s. From 1945 to 1951, nuclear fallout is found locally around atomic device test sites, whereas from 1952 to 1980, tests of thermonuclear devices have left a clear, global signal of excess 14C, 239Pu, and other artificial radionuclides. > > > If it would be possible to examine the composition of the fragments, geologists could extrapolate geological events related to technological eras. This would be similar to today's geologists knowing the composition of the atmosphere millions of years ago just using the fossil record. Please note that traces of the anthropocene exist all over the world, not only in inhabited areas. The question would be whether the cataclysmic event would completely obliterate the geological record (imagine nuking an archaeological site), or add on top of it (imagine dropping napalm on an archaeological site, with enough napalm residue to make an extra layer on top). A planet being ripped into an asteroid belt due to high gravitational [tidal forces](https://en.wikipedia.org/wiki/Tidal_force) is very much like the formation of a planetary ring. Imagine you could send some geologists up to Saturn, and bring back some chunks of its ring. Would there be big enough fragments of the crust to see the geological eras? Or would the fragmentation melt everything together? The harder the cataclysmic event, the harder the geology/archaeology gets. [Answer] On the surface, probably not. While a comment noted that an impact large enough to "fragment" a planet will behave more like a "splat", the implications of this have largely been missed. Such an impact will produce an enormous cloud of ejecta (a significant fraction of the planetary mass) which will mostly fall back to the surface. This will have two effects. First, the impacts will produce an enormous amount of heat, and a lot of the impact areas will become molten, erasing any signs of man-made artifacts. Second, even a small fraction of the planet's mass will bury the remnant surface very deep. For instance, assuming uniform density, 1% of the earth's mass will produce a blanket about 13 miles deep. Given the scale of the ejection event, a fairly uniform coverage should be assumed. As a result, any visiting aliens had better be interested in relatively deep (much deeper than we can do) exploration of the pathetic remnant of a once-living planet. Exposure of core material at high temperature will have locked up all the atmospheric oxygen, and for quite some time the surface temperatures will be high enough to keep the water as vapor (that is, steam). Of course, you may have noticed a possible loophole in the opening sentence of this answer. The ejecta will not entirely return to the surface, and for a shorter or longer period some of it will orbit the earth - we'd probably have a very nice set of rings for a few millenia - and if the visitors are lucky they might encounter artifacts in orbit. The odds on this are not great, but I don't see how they would be zero, either. You'd expect to see fragments of refined metal, and small, dense objects might survive the ejection process in a recognizable form. This might apply to objects such as steel tools and jewelry. Platinum, for instance, is quite hard, strong, and melts at very high temperatures. EDIT Even a badly damaged Rolex would be a pretty sure sign that someone had been on the planet. Unless, of course, the Blind Watchmaker debate is universal. END EDIT [Answer] If the Earth is destroyed to the point of melting the crust and destroying all possible artifacts, there are still those that were not on the Earth at the time. Besides artifacts on the Moon, Mars, Venus, Titan, and various radioactive radio-sending beacons heading slowing to the Oort cloud, there is a cloud of sattelites including many in a rather distant Geosynchronous orbit. These may be scattered rather than vaporized. Even if the expanding cloud batters them, they will also move away and at least some of them may remain as recognisable anomolies in the debris. [Answer] # Radiation Assuming current level technology, the first thing the aliens will find on their scanners would be radiation spots from the melted down [447 nuclear reactors](http://www.world-nuclear.org/nuclear-basics/global-number-of-nuclear-reactors.aspx) that are currently active. This would be a pretty unmistakable sign of civilisation. [Answer] ## Apollo Space Program Artifacts There are actually some fairly significant artifacts which would be much easier to discover than anything on the Moon, Mars or things like puny inter planetary probes... There are [five S-IVB Saturn V third stages](https://en.wikipedia.org/wiki/S-IVB) in heliocentric orbits, and they are all obviously artificial to anyone looking for them. Being that they are twice the size of a London bus, they would be the most likely artifact to be found by anyone surveying the solar system. [Answer] Such a collision would eject significant mass from surface. Nearly all of that mass would fall on the surfaces of Earth and Moon. This would melt and reform both surfaces removing all traces of us on either surface. It would also destroy all satellites orbiting Earth or Moon. This is supposed to be how the Moon was created. (Probably without the part about the traces of advanced civilization being erased?) The collision would do nothing about traces outside the Earth-Moon system, so given some time a record of our existence could be launched to stable orbit in space. Earths L4 and L5 points, maybe? So if you want the aliens to find traces of us, it is easy to do. Kind of interesting to think of what we would choose to record of ourselves and what the aliens would think of it, really. [Answer] > > ...if some alien race discovered the remnants and thoroughly* examined > them* > > > As the OP implies, let's assume no limits on the practical abilities of our aliens to filter the debris (i.e. they are arbitrarily good at forensic study). Diamond (melting point ~4500K) should survive immersion in magma at the temperature of the mantle (~4000K). Therefore, they will find unnaturally cloven gem-stones. The golden ring will melt, the hand that wore it will vaporize, but the gem will remain. Love, truly is eternal. [Answer] The proportion of the different - stable - isotopes tend to be the same in the whole Universe. Nuclear reactions change these proportions, and thus they remain visible forever even after all of them decayed, even after trillions of years. Although our radioactivity changes only a very small part, compared to the mass of the whole Earth. If somebody would mix the whole volume of the Earth, we couldn't measure anything in it. [Answer] It depends the technology earth had at that point. But radio-waves would remain, sadly most of the first human things they may have heard, would be Hitler. Still our legacy may remain and maybe would be possible to pinpoint earth's position. Plus our many satellites and debris would scatter.We would always have the probe we are sending to the edge of solar system (forgot the name) it contains several artifacts from earth including a map to find earth,blood and also music! ]
[Question] [ Closed. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it can be answered with facts and citations by [editing this post](/posts/69615/edit). Closed 6 years ago. [Improve this question](/posts/69615/edit) Vampires are depicted differently in every work of fiction, but one thing mainly stays the same: they need blood to survive. Human blood, to be precise. Some stories add in the rule that they can also drink blood from animals and usually put vampires who make the choice of only drinking animal blood on a morally higher ground than the savages who harm humans. In my setting I want to take this a step further. Vampires are offered two choices to get their blood-fix: either drink from humans, or eat 'blood-oranges', the vampire variant of the snozzcumber. This fruit looks nothing like an actual blood orange and tastes absolutely horrible to both human and vampire, making it tempting to take a bite from a human every now and then. Even when it is common knowledge to them that biting humans will result in either the victim dying of blood-loss or turning into vampires themselves. To keep these two choices absolute, I want to rule out any other source of blood. For some reason vampires need human blood, and don't consider animal blood an option. They can't drink from other vampires either. Vampires are already vampires, it completely takes away the risk of turning them like with humans. How can I explain that vampires only consider humans as possible targets? I'm looking for an answer that suspends disbelief, so it's alright if a solution delves into pseudo-science/occult territory. [Answer] Possible solution: * Allergic reaction. When drinking nonhuman blood, it triggers an allergic reaction, e.g. sickness, blood clumping, and other stuff. This is because of the different components in human and nonhuman blood. The idea behind can be compared to the reaction of your blood, when your receiving an injection with a incompatible kind of blood. * Not filling Human blood has a special component needed by the vampires, e.g. Vitamin V. It can only be found in humans and their nearest relatives. (Blond, busty virgins contain a maximum amount of Vitamin V at their age of 18, so I've heard) [Answer] You can postulate that, together with blood, the vampire absorbs the intelligence of the blood donor. Therefore if they want to stay intelligent, they cannot drink from any species other than humans. Blood orange are the evolution of drinking from humans: they remove the social stigma of neck biting (as suggested in the comments, they mimic the blood used to make them germinate), and being grown in garden, the owner can mix various intelligences (the musician's intelligence, the painter's, the mathematician's, the leader's, etc) to use on purpose, giving him/her a clear advantage on human drinkers (you never find a Mc Giver when you need one...) [Answer] Few, aside from the vampires remember this... but before the current age of man, in the dark eons before recorded history, a precursor of modern homo-sapiens climbed the metaphoric tree of knowledge, attaining for themselves a level of technology which matches and in some ways exceeds that of our current age. An ancient war eradicated those precursors and erased all signs of their civilization, leaving only one legacy which has endured thru to today... Vampires. Vampires are the surviving victims of a vicious bio-weapon which was released across the entire world during the last days of that civilization-ending war. It was a disease which broke the stability of its victim's genetic code; forcing them to regress back along their evolutionary path; devolving into grotesque hybrids of their genetic ancestors. A few "lucky" victims of that plague regressed into a hybrid of man and bat, and thus obtained the ability to drink blood. And in that blood was hidden their genetic salvation. Vampires do not drink blood for sustenance. They absorb it to restore their crumbling genetic code; to remind their bodies of what it means to be human. Without human blood to beat it back, the bat side of them grows and becomes dominant; turning them into mindless, voracious beasts. ...which is where the blood oranges come in. Blood oranges are not a natural product. They were created by the now vampiric precursors to give themselves an alternative to drinking blood. The fruit contains two genetic codes; one which replicates the fruit and the other which is a dormant copy of the original precursor genetic code. The precursors created the blood oranges with the last of their technology, then collapsed into beast form which ironically didn't eat the oranges. Only when homo-sapiens evolved, did the vampires' food supply once again provide them with the genetics building blocks for sentience; allowing them to push back the beast, rediscover the oranges and once again prowl the night as almost men. [Answer] Charles Stross's "The Rhesus Chart" has an interesting take on it. Vampirism is an effect of a parasitic entity hosted by the human being, which creates a need in the vampire (in the same way as some parasites change the behaviour of insects). When the vampire feeds, they create a link between their hosted parasites and their prey. The prey survives the feeding, but over a short period the hosted parasites eat the victim's brain/soul. If the vampire doesn't eat, ultimately the parasites will turn on them instead. The parasites need a human brain/soul, so the need they create in their vampire host is purely for human blood. [Answer] Blood Type matters You could take it a step further, and say that not only does it have to be human blood, but the blood type has to match. Blood Oranges obviously are Type O (so universal) and vampires could probably tell blood type either by smell or first taste. Especially if Vampires lose the ability to create new blood cells themselves, this lends a bit of credibility to the notion. [Answer] The European source of blood need in vampirism originated from the gastric problems of high born. Which in turn came from incest and untreated STD. So anyway, people suspected of vampirism could not eat regular food, or they appeared as not eating (starving look, slim face etc). For normal peasants when you went starving you died in few weeks. But the "vampires" lived. Now, the people believed that there are for fluid in humans: black bile, yellow bile, phlegm, and blood. The blood was associated with vitality, spring and head (hence drinking blood from the neck). And because vampires were not having regular food (and animal blood was a kind of food) they draw a conclusion: if you don't eat but are still alive you need to have life force from something else. The only logical explanation was that they drink human blood. [Answer] Non-human blood is like taking in the wrong blood type during a transfusion, it can be deadly. [LINK](https://www.ncbi.nlm.nih.gov/books/NBK2265/) > > If incompatible blood is given in a transfusion, the donor cells are > treated as if they were foreign invaders, and the patient's immune > system attacks them accordingly. Not only is the blood transfusion > rendered useless, but a potentially massive activation of the immune > system and clotting system can cause shock, kidney failure, > circulatory collapse, and death. > > > Or, how about the nutrient value? You can fill up on non human blood but it does nothing for you, like candy. You cannot survive on it and it creates other problems. [Answer] Not every vampire myth requires the vampire to only consume human blood, but having said that its your world and in many stories they do so there's not reason not to have them do it. In that case perhaps it is because vampires having once been living humans need human blood to enable their body to properly function, only human blood cells would be of the correct shape and size to properly travel through all the smaller blood vessels and capillaries in the body. There are several types of anemia such as sickle cell and vitamin B12 where blood cell abnormalities cause problems. Blood cells from other animals would not be of the the correct form to travel through the circulatory system fully. This relies on a couple of things, that they do not digest human blood and break it down but rather absorb it in their body through their stomach and gut. Also they drink human blood in order to allow their undead metabolism to work, just as in human bodies blood allows the transport of oxygen for use in the Krebs cycle to create the energy the body needs to function. It would also require that for some reason in their vampire state they can no longer produce their own viable blood cells. [Answer] Depends on the nature of your vampires. Are they the result of an ancient curse? Or just magical creatures? In the former case, the need for human blood is just part of the curse, and the harder to sell thing is any substitutive, like the blood orange. If they are just magical beings that have existed as long as humanity... Well, it's the same, they need specifically human blood because that's how they are (yes, "because magic"). Actually, you don't really need to explain that You see, the vampire is a pretty stablished creature. Their main defining trait is their need of human blood. Once the reader sees a close-to-classical vampire, that need is assumed and it's everything else (animal blood, blood oranges, no real need but a sort of addiction, etc) that have to be explained. [Answer] Let's assume that your vampirism is a product of some extremely rare disease (I'll call it Maledicto Sanguisuga). This disease is caused by colony of weird bacteria which binds itself to its host and transmits to another victim on very specific circumstances. The symptoms are rather bizarre as well: * Extended lifetime of the host: these bacteria can rarely find a suitable host so surviving as long as possible within the body of current host is essential. Therefore these bacteria repair and revitalise host's body tissues and cells to the point that host's body doesn't need to consume any more food (actually, host shouldn't consume any food at all - who know what they put in there). * Superhuman abilities: longevity is good but even undying host is not immortal. These bacteria are allergic to sunlight, which is why high speed (vampire's quickness) is mandatory. The host can get into a fight or get stuck in the trap, which is why high strength is quite useful as well (and let's throw a superhuman senses for good measure). * Host is rather pale and skinny - these bacteria feed on host's blood, replacing it's cells with itself. Since host cease to produce new blood (he can't eat anything), he has to drink other people's blood (or blood oranges as the only suitable substitute) to keep his bacteria fed. Long periods of hunger force bacteria to cause pain to its host (motivating him to find food for bacteria) - hence the slips of sanity. I know, it sounds like "nanomachines, son" explanation, but... [Answer] Use genetics! Blood is basically [water containing proteins, glucose & minerals](https://en.wikipedia.org/wiki/Blood) used to deliver & distribute nutrients throughout the body of most mammals, we need something to differentiate human blood from that of other animals1. Something you could make use of is the fact that [white bloodcells are an excellent source of DNA](http://www.biology.arizona.edu/human_Bio/problem_sets/DNA_forensics_2/06t.html). You could make your vampires more parasitic and have them require fresh cells with plenty of easily accessible DNA in order to fix their own cells and thus bodies. Consuming the blood of another animal2 would result in their system using DNA from these animals and thus producing cells that might not work together with the rest of the system, effectively mutating them into grotesques that cannot sustain. As for your blood-oranges: You will to have to create them in either a laboratory or in some magical alchemists workshop, thus there is no problem in making them carry either human DNA or some generic bits that the parasite can sufficiently use and combine with their own genetic material. 1As you also mention in your question. 2Yes, humans are animals! [Answer] ## Vampires do not Produce Enough Blood on their Own The short idea is this - vampires are parasitic creatures with a trade-off: in exchange for the abilities they possess, their ability to produce blood on their own is hampered. The key word being hampered. They can/do still produce blood on their own, but at a rate that is slightly less then they require. Of course, you can adjust the rate they produce blood yourself to suit your story - anywhere from needing a top-up only rarely to every day. ## Their Teeth Direct Blood Directly to their Veins (and/or "Blood-Bladder") Rather than "drinking" the blood and extracting nutrients from their stomachs, the blood they steal from their victims via their fangs goes directly into their own bloodstream. One pesky problem with this approach is that if they need to drink 5-6 pints to kill a person they themselves would need to be down at least 5-6 pints... and they would be dead by then. And thus the "blood-bladder" is introduced; an elasticized internal vein that can swell to hold blood. This direct transfusion process explains why vampires cannot drink animal blood. They literally use the blood they consume and (like people) are not compatible with other animals. This mechanism has the added potential story benefit/issue of allowing vampires to neatly deal with (and possibly contract) disease, if you want to go that route. Have a bad flu? Go chomp on someone who recently got a flu vaccine and put their white blood cells to work. Tough luck if you eat someone with the flu though. The blood-borne disease issue can also be sidestepped by simply noting that vampires produce excellent quantities of highly effective white blood cells that take care of pretty much any blood-borne entities that are not beneficial to the vampire. Perhaps their self-produced white blood cells learn from every white blood cell they injest, making older vampires much more resistant to disease than newer vampires. ## The Blood Orange Remember how we said that vampires do not produce ENOUGH blood on their own? Well, "blood oranges" contain particular enzymes that stimulate increased blood production. I would suggest that unlike human blood, blood oranges are probably consumed in the traditional fashion. [Answer] My understanding on why vampires need to drink human blood is because "the life of the flesh is in the blood". (Lev. 17:11a) Of course, not all vampires require blood. Incubi and succubi are considered vampires, but they rely on psychic energy. [Answer] This has idea has been touched in a number of works. The most popular reason is simply that human blood is the only kind that is sufficiently nutritious. Compare it to a human only eating cabbage. You'll survive for a bit, but cabbage won't keep you alive in the long run. In the same fashion, a vampire CAN use animal blood, but they can't live for sustained periods of time on it.There WILL come a time when they need human blood, no ifs, ands, or buts. [Answer] ## If you want an odd but interesting pseudo-science answer, then go with quantum nutrition. Every object with mass has an effect on the spacetime around it. Certain objects bend space in just such a way a particular way that they have unique properties above and aside whatever the object is used for. Thus, human blood has a unique flavor and/or nutrition based on the manner in which human blood (or a component of the blood) bends spacetime. Perhaps a protein chain, or a peculiarity of the DNA or RNA sequences of certain blood types. This exact chain is not duplicated in anything but this one particular plant. And that would give you exactly two sources of nutrition. And a species very likely to die out should anything (mutation, population drop, etc) happen to the food source. [Answer] Because of their ability to regenerate and heal quickly, vampires are very hard to kill. However, the vampire conversion process causes a flaw in their DNA, and so they need an outside template to use in order to repair cells correctly. If a vampire feeds off of a plant or animal with non-human DNA, then there is a DNA mismatch which can cause rapid cell death. This is why vampires will get sick when they eat normal food. Their bodies try to incorporate this foreign DNA, and in the process causes stomach problems that trigger the vampire to expel the meal. The part of the blood that has DNA is the white blood cell, and it has a pretty short life of 5-20 days. This would give an idea of how often the vampire would need to feed. The real question is how the blood oranges work if it's the DNA that is important. Say some vampire elder worked out a way over the long centuries to splice plant and human DNA, and came up with a hybrid that contains enough human style DNA that it can be eaten without making the vampire sick, and allow for a DNA template. It would be imperfect compared to real DNA, but if the important parts matched up then it would serve it's purpose. It could be that real DNA gives greater vitality, but a vampire with a conscience or who wishes to remain hidden could live off of it without problems. On a side note, rapid cell regeneration would account for problems with vampires in sunlight, since sunlight contains ionizing radiation, and that can damage cells. If the cells are being damaged and rebuilt very quickly, it could cause metabolic problems when exposed, that they wouldn't have with artificial light. ]
[Question] [ It's the future. The setting is about as "hard-ish sci-fi" as it is possible to be, with the one big exception of a viable FTL engine. Humans have began spreading out into the galaxy, colonising nearby star-systems that have compatible exo-planets. There are currently about 100 colonies, spread over a roughly 1000ly wide region. Travel times between stars frequently take multiple months. Humans still appear to be alone in the galaxy, but some questionable ruins of more primitive civilisations have been found. The plucky humans are about to have a surprise run-in with a vastly more powerful civilisation, who instead of setting out into the galaxy, decided to stay at home and construct a Dyson swarm. The star hosting this swarm is only a hundred light years or so outside human controlled space. They built it a long time ago, so nobody on earth would have noticed it under construction. Never-the-less, I would have thought that the spectral lines and luminosity of a star with a few billion giant discs orbiting it would be different enough to be visible by future astronomers. How and why did my future astronomers manage to miss this feat of stellar engineering on their (relative) doorstep? I would expect an answer to fall into one of the following categories: 1. Human astronomers saw the unusual characteristics of the star, but dismissed it as a natural phenomenon for some reason. 2. The Dyson swarm builders constructed their swarm in such a way as to hide the fact that it is an artificial structure when seen from interstellar distances. [Answer] Simplest explanation: until recently, humans simply didn't see the star directly as it was hidden behind a small, but thick star-forming nebula between it and Earth. (One doesn't really exist, but one could.) The nebula has some young, hot stars which are in the way of the star you're interested in, obscuring it. Only recently have humans expanded "laterally" to the point that they can clearly see around the back of the nebula to get a clear look at the star, and surprise! If it's a dark nebula, then it doesn't have to be star forming or have any stars. The star might be detected in the infrared, but without visible spectroscopy it might not seem anomalous and just be considered a red dwarf or something that isn't very luminous. [Answer] They’ve been actively trying to hide. These aliens don’t want to be found. As such they actively keep track of nearby astronomical phenomena that indicate younger civilisations and, upon detecting them, engage in active surveillance/espionage to track their expansion. Their Dyson swarm is actually very efficient, and will capture almost all energy unless the energy collectors are folded/rotated/made translucent. In this way the aliens can selectively leave ‘holes’ in the swarm to make it appear to any given nearby star that they are just another normal star. This also has the effect of turning their star into a shkadov thruster that constantly moves on a vector away from other races. But every hole is less energy being collected, and humans have spread so far so fast (galactically speaking) that these aliens can no longer capture as much energy as they want to and maintain the illusion of normalcy. As such they have abandoned any pretence and just set their swarm to gather as much energy as possible as quickly as possible, effectively ‘turning down’ the star overnight (an event sure to get people’s attention!) Humanity just has to wait and find out what they’re going to do with all the extra power... [Answer] > > “Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.” > > > - Douglas Adams, The Hitchiker's Guide to the Galaxy There are two reasons why your civilization doesn't spot the Dyson Swarm ("DS"), which together make the DS functionally invisible. 1. *Space is really* big. We already have problems even finding other countries' secret military satellites, and that's on the scale of a planetary orbit. 2. Your hypothetical civilization has FTL.** Due to the above, one of the only ways for your civilization to find the DS is if one of their ships does a fly-by. Your civilization figured out how to use FTL quite early on, so they tend to go through the outer reaches of the system at superluminal speeds. Such high velocities are good for getting places quickly, but make sightseeing practically impossible. Anyway, why would people want to look at that area of space anyway? It's just a bunch of boring old asteroids. --- So, your civilization goes for a few hundred years without noticing the swarm, and everything's fine. However, they still think that 150 times the speed of light is pretty slow, so they put a bunch of money into developing a faster drive. Eventually this investment pays off, and they come up with an Asimovian hyperspace drive. This allows them to get from point A to point B in literally no time at all, skipping the years spent in transit. There's only one catch. Although the hyperspatial drive is very good at getting you from point A to point B without having to go through the rest of the alphabet, there are some complex calculations involved. So complex, in fact, that you can't do them without the newest in supercomputing technology. Already extremely difficult, these computations become almost impossibly hard when you toss in a gravity well. Despite having multiple [space drives](https://tvtropes.org/pmwiki/pmwiki.php/Main/ItRunsOnNonsensoleum), your society still hasn't managed to prove that P = NP, so hyperspatial drives are only used for the interstellar portion of journeys. The new drive makes 99.99% of a trip go by in the blink of an eye, but the remaining 0.01% has to be made with other means of propulsion. Unfortunately for aspiring day-trippers, traditional FTL drives interact explosively\* with hyperspatial drives. The only other option is ionic thrusters, which are decidedly non-FTL. This forces ships to go through systems at sightseeing speeds. If only there was something out there to sightsee... Space may be vast, but so is a Dyson Swarm. Without anything else to do, bored passengers soon spot the swarm. \* Actually, it's a topographically complex n-dimensional spatial fracture, but the end result is the same. [Answer] I'm not too familiar with star characteristics, so wouldn't know what humans could or would dismiss as natural. But I have some ideas on how to hide such a megastructure: Full coverage If this civilisation is as advanced and powerful as you state, and they have the resources to actually construct a Dyson swarm effectively, they might have had enough resources and/or time to fully cover their star (potentially with large screens). This is vastly dependent on which distance from their star they can survive at, being much shorter than our distance from the sun. Full coverage would effectively hide the star altogether, and there won't be anything to investigate. Alternatively the coverage could be semi-transparent, making the star appear much weaker or smaller, and less interesting. Little/thin coverage Another option is the opposite of above, the strips or structures are so thin and spread out, or form such a perfect raster, that it can't be easily spotted from earth with conventional methods. Only if a star is of particular interest to Humans, they will investigate further. This star didn't look too noteworthy, so they didn't look too close. Asteroid belt Our sun has a huge asteroid belt around it, at a large distance. However this doesn't have to be the same for each star. Stars might have asteroid belts at closer proximity to their sun, and such won't be an uncommon sight. An option would be that this particular Dyson sphere was constructed to closely resemble an asteroid belt, and as such won't be easily spotted as artificial. Glass The entire Dyson sphere could be constructed of a resource abundant to this race, which just happens to be fully transparent. This would mean they would probably struggle with privacy, but by large their structures would be hard to spot at intergalactic distances. Simply because there isn't a construction large enough to spot which you can't see straight through. Structural integrity issues handwaved for the sake of this option. Up in the crowd All in all, humans might have spotted something slightly off with it, but it wasn't too noteworthy, as the star was of little interest to begin with. Due to the vast numbers of stars in the universe with potentially "Something off" about them, it was thrown on a pile of "Perhaps we should monitor this" and simply forgotten about, or there simply wasn't enough funding or time to efficiently investigate. Stolen thunder The star might be in (semi-) close proximity to a huge unexplainable celestial anomaly, which is of massive interest to us, and thus is largely overlooked because anyone looking that way is quickly distracted and only pays attention to the anomaly. This option might backfire though as they might investigate the effect of the anomaly on nearby stars, depending on what it is. Down low, too slow The star is only properly visible from territory humans only recently expanded to (note, expansion can work linear as well as spherical). They did notice the anomaly, but were too busy developing their settlement that they didn't pay enough attention quick enough. They have their run-in with the other race before they know what's going on. Alternatively, we only just might have stumbled into what they consider their territory, and they are rushing to squish the new menace. [Answer] ## It was never deemed worth investigating closely. So actually, we know it's location, and have for a hundred years or more. Every 10 years or so some astronomer gets excited, gets a grant and does research on it; usually the conclusion ends up that it's a star that's being mostly occluded by an asteroid belt. Because all of the planets in the system were used in the construction of the Swarm, the stars wobble is non-existent (this is how we can tell which stars have planets in the current day), despite the odd interference it's obvious there are no planets, making it a curiosity at best. Once someone even proposed that it was a Dyson Swarm, but a competing astronomer got better grants and suggested an alternate theory that got the first guy discredited. Like obviously something is weird about it, but ultimately there are plenty of better prospects for potentially habitable worlds, and the expense of sending probes (or a manned expedition) is prohibitive compared to the potential benefits of going to a star that apparently has a big asteroid belt and little else. So until recently aside from a study here or there every 10 or 20 years it's been basically ignored. Finally someone got enough money to send a probe (or expedition) and the truth of the matter is discovered. Or maybe a new colony looks at it from sufficiently parallax view to see that the swarm isn't just a band of asteroid and a closer look is finally called for. [Answer] The Dyson swarm isn't actually between the star and us The alien's Dyson swarm isn't a full shell - instead, it is more of a ring, with some objects being perhaps a few tens of millions of miles of what used to be the planentary ecliptic. However, the view of the star from the poles is largely unobscured. Of course, one of the poles points almost directly at the human empire. Because the view of the star (from the human perspective) is unobscured, observations of the stellar spectra and intensity wouldn't show anything interesting. And, as the objects of the ring are relatively balanced, the star wouldn't shift much (with is the other current method used to find exo-planets). It's possible that future technology would be able to detect the ring itself; however if the star is relatively uninteresting (long in metals if the aliens really went hog-wild in mining stuff from their sun), it might be put fairly low on the list of things for astronomers to check out... [Answer] The swarm are really small objects, enough to be disguised as interstellar dust If each unit is comprised of elements in the order of centimeters and surround the star, it can easily be confused. Only a probe sent specifically to study the star would find something off, and even then a second one would be needed to certify the findings. [Answer] You don't need an explanation - there could be Dyson swarms all around us and we might not notice Let's think about what scientists will see if they look at the star. They might see it dimming and brightening a bit as the distribution of solar panels around it shifts, but stars dimming and brightening every so often are [nothing new](https://en.wikipedia.org/wiki/Variable_star). Its spectrum would also have a slight dip along a wide range of frequencies, but this kind of feature is unlikely to be seen as abnormal. Every star has its own spectral distribution, with slight variations. Unless the effect of the Dyson swarm is a sharp peak or trough in a few very specific frequencies, nobody would look at it twice. And we'd expect that the solar collectors in the swarm would absorb a wide range of frequencies, like our solar panels today do. So in the first place, it might not have any unusual features. But let's say for argument's sake that it does have some unusual features. We still might not notice. There are so many dang stars that nobody looks at most spectra by eye - everything's done by algorithm, which is why a feature that nobody's looking for will be unlikely to be noticed. Sure, maybe some studies will be looking for alien structures specifically, but the star's spectrum might be weird in a way even they don't expect, and these studies might not single it out. Okay, but let's assume that we get lucky and some study happens to pick out this one star and examine it and it happens to be pretty strange. Well, we have a bunch of stars like that now, and the best funding we throw at them is a few hours of telescope time a year. They could try to get together an expedition to travel to the weird star, but unless they have some other evidence that it's aliens, it's completely plausible that nobody cares enough to do that. After all, it's 100 ly outside of human-occupied space. That's several decades even with your FTL, followed by a several-decade return trip. If your study can't be finished within the span of a single student's second degree, then nobody will take it on unless it's unquestionably Very Interesting. Basically, unless this Dyson swarm causes the star to freak out like [Tabby's Star](https://en.wikipedia.org/wiki/Tabby%27s_Star), we won't notice it until someone basically runs into it. And to quote Dr. Boyajian herself, > > Extraordinary claims require extraordinary evidence, and it is my job, my responsibility, as an astronomer to remind people that alien hypotheses should always be a last resort. > > > So I wouldn't worry about any serious researcher singling out the star and getting a full mission together just because it might be a Dyson swarm. [Answer] Taking advantage of the fact that FTL implies time travel, every time they get discovered, the aliens fly back in time, violate causality, and destroy whatever human noticed them (or at least the records of the discovery). The fact that they have been discovered now just means humans have finally learned to patrol their own backstory. My favorite write-up, with pictures, explain why FTL violates causality using just geometry. Straightforward even if you’re not a math geek: <http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-time-travel> [Answer] It was mis-identified as a planet A Dyson Swarm is a beefy beefy project, for efficiency, the individual satellites are constructed near one another in a spreading region rather than deployed evenly around the star. For whatever reason, they stopped building, perhaps they ran out of resources, or they simply got far enough to feel they had enough. Maybe they're still building when they need to, but progress has slowed. The swarm is a dark stain that orbits the star, incomplete, but still incredibly large. But to the telescopes of the [various planet-finding agencies](https://en.wikipedia.org/wiki/List_of_exoplanet_search_projects) it's just a large object transiting the star and looks exactly like a planet. Nothing important, most stars have planets of some size. They log that there is a super-earth type planet in the habitable zone of the star and move on. Perhaps noting some unusual spectral data about it as they go. The truth is only revealed when someone finally goes to visit the system and discovers that what they thought was a large planet is in fact so much more. [Answer] Humans use Portals and Hyperspace to travel, and ignore normal-space most of the time In Peter F Hamilton's Pandora's Star, humans create portals to far-off stars. Normal-space ships are mostly not used. So most star systems are given only a cursory glance, and left behind. So a secret-in-plain-sight military base is built around Alpha Centauri after public interest in the closest star wanes. No one builds a portal to it. No one travels to it via ship. It's just present, able to portal out or normal-space travel wherever it needs to go, and the public is unaware. Similarly, your invaders can be patient normal-space builders using thousands of years to spread between stars. Humans flit about with FTL, unaware of the huge number of ships approaching until the decelerating drive plumes turn on. [Answer] Two words: Tabby's Star This is a well-publicized stellar observation that was thought, briefly, to be potential evidence of a megastructure similar to a Dyson swarm, perhaps one still under construction. It's now believed that this star's gradual and irregular (but quite deep) dimming is due to dense clouds of dust, likely created by planetary formation collisions (big pieces stick together, little ones are ejected temporarily). Since this was determined (right or wrong) any star we see with similar light curves will be thought to simply be young enough to still be forming its planets. Astronomers might well put it on a list of anomalous stars if the spectral data seems to contradict this young age -- but with the number of stars to be seen even in a mere couple hundred light year sphere, it might be a long time before it seems important enough to go look -- and until someone goes and looks, the swarm builders either won't know we're out here, or won't consider us a likely threat. First time a ship drops out of FTL close to their system (say, without a fraction of a light year), that may change... [Answer] ## The Dyson sphere is complete, and cooled to ~2.7 Kelvin Basically the star is completely invisible because all the star's radiation is captured by the Dyson sphere, and the sphere itself is kept cool, so it's blackbody radiation is the same as the background. They manage the cooling feat by a giant laser directed into empty space, or [dumping it into an artificial black hole](https://worldbuilding.stackexchange.com/questions/144032/black-holes-as-heat-sinks). The linked question asks about a portable heat sink, which an answer shows that it requires a black hole the size of the moon. But your aliens don't need to be mobile at all. For the motivation, I'm not actually sure if this is more efficient than uniformly radiating heat. I suspect there have to be losses somewhere, but black holes seem pretty magical anyway. However if the civilisation is smart enough to build a Dyson sphere, they'd be smart enough to see humans too, or at least predict that some alien intelligence might be a threat. And because they decided to keep all their eggs in one solar system, they'd treat security seriously. With the logical conclusion that only way to win a war against a galaxy spanning civilisation is to not fight at all. Thus being perfectly stealthy was a design requirement. Finally they were discovered by sheer luck, when an exploration ship crashed directly into the the solar panels without seeing them. Because the solar panels are incredibly thin and light, the ship survives and uses it's backup engine to return to base and tell of their discovery. ]
[Question] [ In my world, a group of "lamplighters" seek to turn off unused stars to conserve the energy for later use. This serves a few purposes, but mainly: * It delays the heat-death of the Universe to some insanely distant point in the future. * It can be used to preserve a planet's history. For instance, if our own sun was about to become a red giant, it could be turned off as to avoid destroying Earth and all of its history. I want to know if there is any conceivable way to stop a star from burning. Ideally, this would happen without destroying any exoplanets, but that's not a requirement. The only requirement is that a good portion of the mass is left over for later use (e.g a black hole wouldn't work for this). For the sake of this question, let's say they have near-infinite resources at their disposal. The only thing I can think of at the moment is smashing the star with some gigantic, dense object a few times its size. But even then, I'm not convinced it would be effective. Even if it was, slowing down something with that much mass afterwards wouldn't be easy, even accounting for near-magical technology. [Answer] If you’re aiming to eke out the universe for as long as possible then ‘turning off’ your stars isn’t that good. A better plan would be [star lifting](https://www.wikipedia.org/wiki/Star_lifting). This is, in effect, turning off the star by pulling all of its fuel away (Note: Only very advanced, already powerful interstellar civilisations need apply). It might help to have a Dyson swarm already at your disposal to give you enough power to lift and sequester all the yummy light elements. Two ideas for how to do this both use whopping great magnetic fields, with the first causing stellar mass to ‘pop’ from the star in large coronal mass ejections that you can then scoop up. The second basically comprises spinning the star ever faster until it tears itself apart. Both need lots of energy, but hey, you’re turning off a star. Oh, and you’ll need to take care in your calculations that you don’t destroy whatever planet you’re looking to preserve, Then (and this is the trick) you don’t bother turning that star back on. Make a new one. Or a series of new ones. You’ve already cracked fusion, right? Get just the planet you’re interested in and heat it with a tiny (comparatively) fusion reactor and a load of big lamps (probably more complex than that, but your civilisation can handle it!). If you properly husband the fuel from the sun you can heat one tiny little planet for a long, long time before you run out. In the meantime the rest of the universe will freeze, but hey, who cares, right? [Answer] In a nutshell, a star is an ongoing nuclear fusion contained by gravitational energy. Turning off the star means stopping the fusion. That would mean either removing enough mass to remove the moderation, or freezing the mass to prevent further nuclear fusion. Removing mass would set off the explosion of the star and also weaken the gravitation bounding with the star system, so it won't help preserving it. Cooling the star down to the point where coulomb repulsion would overcome again the gravity push would be a better way, but won't work for preserving the star energy, since you would have to get rid of all that energy. [Answer] Stars run on nuclear fusion, specifically the fusion of protium (plain hydrogen with no neutrons added) into deuterium, a process that, as far as we know, only takes place in the cores of stars (in nature). In the process, on of the fusing protons emits a positron to convert into a neutron. A more complex decay (due to more protons involved) takes place in any fusion even, whether it's deuterium-tritium, deuterium-lithium, lithium-boron, or oxygen-carbon (in the end stage of a pre-supernova collapse). The fusion itself is governed by the strong nuclear force -- the very short-range force that overcomes electrostatic repulsion when protons get close enough together, and thus holds all nuclei heavier than protium together. The decay of one of the fused protons into a neutron is governed by the weak nuclear force, which covers essentially all radioactive decays other than fission. If your Lamplighters had access to a method of locally suppressing the weak force, they could "turn off" decays like beta (positron or electron emission). This would result in production of helium(2) (which doesn't exist in nature) instead of deuterium, and stop the emission of much of the energy produced by protium fusion (by preventing annihilation of positrons with the abundant electrons in the stellar plasma). Important caveat -- if the weak force suppression fails after even a second of operation while enclosing an active fusion core, it'll be very, very bad. Instead of the He(2) decays to deuterium taking place at the rate of protium fusion events, when the field drops those decays that were prevented by the weak force suppression will take place at the half-life rate of that decay. I don't have a figure for how long the half-life of the beta decay in protium fusion is, but it's short. Much shorter than the rate of fusion in an active star. That means that if/when the field drops, there will be a huge spike in beta decays in the "shouldn't exist" helions (made up word), meaning a sudden very large flux of (IIRC) 3.56 MeV gamma photons from positron/electron annihilations throughout the core of the star, resulting in sudden very rapid heating and an end effect similar to a supernova explosion. [Answer] Freeze the star in time. According to this <https://www.quora.com/If-time-were-to-stop-suddenly-would-gravity-still-apply> (Which isn't a reliable source) you could lock the explosions in time, effectively turning the star off. But the gravity would still happen, so all the planets would keep circling. Or I am reading this really wrong, but then, just handwave how it works. [Answer] Break the biggest starts into smaller ones. That will require disassembly and reassembly. The lifetime of the brightest, most massive stars is in the order of millions of years. But red dwarves might last for trillions of years ([see their wiki](https://en.wikipedia.org/wiki/Red_dwarf)). That is such a long time that we don't even know if protons would be stable for that long. [Answer] It's tricky. The first stage does use an artificial Reissner–Nordström black hole, or other supermassive and robust "shaver" object. This is dropped towards the star and placed in an unstable orbit, near enough to create a workable Roche lobe inside the target star. This allows bleeding mass off the star until it reaches the Roche vertex at the expense of both the star and the "shaver" object's angular momentum (the latter will have to be replenished using the same engines that moved it into orbit). At the intersection of the two Roche lobes there is a saddle in the gravitational potential, and in that point the infalling mass can be diverted with comparatively little effort. By carefully balancing the shaver's orbital parameters and using appropriate electromagnetic capture and accelerator fields, it ought to be possible to "bleed" mass off the target star and impart it enough kinetic energy to send it into a far orbit to form a "smoke ring". We will probably need a good number of "shepherd satellites" to keep the ring stable (in the picture, of Larry Niven's Smoke Ring, the main shepherd is the darker spot bottom right - Goldblatt's World). At the same time it should be possible to bleed some of the excess thermal energy from the incoming mass to reduce the total energy expenditure (the gravitational binding energy of a star is something huge, and however we dismantle it, even with leaving the massive core in place, we will require an unholy amount of energy - the difference between the gravitational binding energy of the star and that of its remains plus the Smoke Ring). At the same time, the mass loss will cool down the star, extending its life considerably, gradually enough not to trigger a core catastrophe. Ultimately, it might be possible to completely evacuate all fuel mass, leaving the burnt-out core alone to cool off. In stars whose core is above the Schönberg–Chandrasekhar mass limit, the cooling off of the core (and actually the removal of too much of the fusing fuel) will trigger a core collapse, possibly accompanied by several "flashes" when the progressing collapse ignites higher-order fusion episodes in the outer envelope (helium, carbon etc.). This might present a risk to the integrity of the Smoke Ring. Very large stars probably cannot be safely bled past a certain point; as soon as the fusion slows down, [the star will begin to contract and heat up](http://astronomy.swin.edu.au/cosmos/c/core-collapse), comparatively rapidly burning through the carbon, oxygen and silicium stages. When the carbon process stops, there are less than one thousand years to a respectable supernova-like explosion. Unless somehow (more bleeding satellites?) a lot of mass is removed at great speed, easing the pressure and slowing down the collapse. [![enter image description here](https://i.stack.imgur.com/DdNj7.png)](https://i.stack.imgur.com/DdNj7.png) [Answer] In hard sci fi, what you would actually do is siphon off mass from the star and store it elsewhere (or just use it for other purposes) since smaller stars burn more slowly due to the reduced gravity (which is what drives the fusion in the first place). This is called star lifting. The extreme end of things is to remove so much mass that the force of gravity is no longer able to support fusion and just turns into a gas giant like Jupiter, and store that excess mass somewhere else. Then you just dump all that mass back in when you want to re-ignite the star. You should check out Isaac Arthur's YouTube video on star lifting. He discusses it for exactly the uses you mentioned, as well as other purposes. Apparently, it doesn't require any unknown physics and is mainly a matter of scale and therefore not a difficult endeavor for a civilization with infinite resources <https://www.youtube.com/watch?v=pzuHxL5FD5U> But uhhhh...moving reducing that much mass might mess with your planetary orbits. [Answer] Anti-gravity field Fusion in a star’s core relies on gravitational pressure. You simply have to reduce the gravity/pressure to a point where fusion is no longer possible. Of course we don’t know if it’s even theoretically possible to produce anti-gravity, but you can just hand-wave it. In fact, anything which stops time, counters gravity or replaces the star’s core with an element which is at least as heavy as iron would work to stop fusion. [Answer] # Slow down time for the star One idea I've seen in some hard science fiction (especially John C. Wright's books such as The Golden Age trilogy and Superluminary) is to "put something away for the future" by orbiting it just outside the event horizon of a black hole, so that time becomes almost infinitely slowed down for that object. Then when you want it back, you use another mass to pull it up to a higher orbit and back into "normal time". I have not the physics knowledge to explain how or whether this would work for our sun. Maybe some other answerer could flesh out this idea. [Answer] You just have to realise that 85% of all stars in the universe ARE actually switched off by an unknown advanced civilisation. Physicists on earth call these switched off stars "dark matter", so you can see that its already be done ! How it works ? Who knows ? Physicists nowerdays do not even understand what "dark matter" really is, so you don't have to deal with that question, just assume it is possible to convert normal matter into dark matter and vice versa.. [Answer] This is more of a side-remark that the lamplighters goal of keeping the universe alive most likely would not have stars as main goal: Near-magical technology or not, in the end you'll always run against time. This time of cause, your deadline crunch isn't the next week, but the end of the universe. But then again, the scale of your goal is on a whole other level as well. So, let's say we want to save as many stars as possible from burning out. Then it'd only make sense for us to go after those stars, where we maximize the ratio of saved hydrogen to used effort. It is said that we are comparatively in a young phase of the universe, and as such most stars have yet to be born. These future stars are now just a cloud of hydrogen, and as such they are easy pickings. Not only is there no strong gravitational field that binds the mass together, you also don't need to disperse all of the hydrogen to stop a star from becoming. All it takes is a good number of cores you disperse throughout the hydrogen cloud, each acting as the core of a future gas giant that may be close to a sun, but is not quite there. Given that your civilization is at a very high technology level, they still might have spare time for stars burning already. Nevertheless, their main focus would be those clouds, and their doing would shape the universe. As a bonus you'd see them only sporadically turn off a big star (and not immerse the universe in darkness, which would make them out to be an enemy of all life) [Answer] Long story short: Spin it very quickly. Short story Long: You want centrifugal force to overpower gravity. Although not very energy efficient, hypothetically the energy could be returned by feeding off the spin later. You'll expand the star without increasing mass, stopping fusion from proceeding further. Of course, the core, where the gravity is stronger, will pull apart last. This means the act of spinning may revert the start to dust cloud (It's a pretty large grey area between breaking the start apart and spinning fast enough to prevent fusion, and I don't know where the two are in relation to eachother, that'd take more math than I'm putting in at the moment.) But then again, a collapsing dust cloud is how to make a star, so it still works. The hard part is doing this without adding to its mass. This can be done by shooting large masses near it in near-collision orbits. Hypothetically, it would be done to several stars at once to be worth it, each one it slingshots getting sped up. [Answer] I think if you wanted to stop a huge mass of elements from interacting with each other and protect the planets in the orbit. You would need to either stop time in that area or just absorb their energy completely and put a substitute mass in the star's place. This group could create some super high tech machinery like a dyson sphere. But instead of absorbing the star this sphere will create a controlled environment where atoms wont interact with each other. And the machine will only work with the radiation from the atoms. When they want to turn it on again they could just nuke it to kickstart the chaos inside the star. But when a star turns off for a planet that planet gets cold, changes climates etc. so keep that in mind as well. [Answer] Whatever is done will need to be very drastic and well beyond the realms of what humanity might achieve in the foreseeable future. Basicly its not going to happen. However if some new physics became available it might just be possible I suppose. One way of "parking" the star so that it did not burn through all of its energy would be to cut it into pieces. The pieces would then form smaller stars or (with luck for very small stars) brown dwarves the rate of fusion would be greatly reduced. The brown dwarves could orbit each other and be reformed at an appropriate time. Next question how do you cut up a star - I don't know – that’s where the new physics comes in. And yes I know it would be very difficult and and... [Answer] Doesn't helium (or any heavy atoms, I suppose) poison the hydrogen fusion process? If you have near-infinite resources, you could dump helium to prevent the chain reactions from taking place. I don't know how you'd restart a helium-poisoned sun, though. They use a divertor on tokamaks to get rid of the "ash," but whether or not something like that could be cobbled up at a stellar level might need too much handwavium. [Answer] Squeeze It Through a Worm-Hole Create a stable worm-hole that traverses space and time (not a new concept). Choose a worm-hole architecture that can bind to gravitational wells in space and has a fixed length in the time dimension. Then, connect one end of the worm-hole to the center of the star now, and the other end to the center of the nearest orbiting planet at a time a few billion years into the future. The result will be fresh nuclear fuel from the present rushing through the worm-hole and pouring onto the surface of the star's future self. Note that attaching the receiving end to an orbiting planet (rather than the star's center) is necessary to ensure the desired direction of flow, using the star's own internal pressure and gravitational potential differential to force material through the worm-hole. Once you've mastered this basic technique, consider improving it to where it can bind to a smaller gravitational well, as that would help avoid having to destroy an entire planet each time you do this. [Answer] Flood the star with COLD neutrinos (you'll need a lot of them). They will clump in the core and cool it (those that manage to interact with the star's matter will fly away). The star will become something like a white dwarf (degeneracy-supported), but cold. Works for a rather small stars (1.4 sun masses or less), but they are a majority anyway. p.s. you have to support the star in that state by cooling it periodically, or it will self-ignite because of the heavy radioactive elements that will tend to heat it from the inside. ]
[Question] [ I am in trouble: my boss, a multi-millionaire, has just come up with a scheme, but it has problems and he wants me to solve them. The whole thing started when he saw this picture: [![there are 571 billionaires in the US, and not one of them is batman](https://i.stack.imgur.com/gFM2j.jpg)](https://i.stack.imgur.com/gFM2j.jpg) This gave him an idea: invent, develop, and sell "superpowers". These "powers" would not be biological (he's rich, but not that rich), but technological. Basically, he wants to have Small Hero Five-and-a-half (tm) working for him, constantly cranking out new tech. After he has his team invent the tech (with possible help from [Anderson Robotics](https://scp-wiki.wikidot.com/anderson-robotics-hub)), he would start to mass-produce it (think: bat-mobile factory), and sell the gadgets (why sell the rights, when there is still more money to be made?) to would-be super-heroes. This is where the problems start: the reason no-one has done this yet, is that there isn't really any demand, since super-heroes are just overkill against your average crook. Also there are legal issues, as this tech might result in collateral damage (read: Sokovia). His solution to this problem is simple: don't only sell to "heroes", instead "losing" some of it, that will later turn up on the black market. Hey presto, we have a demand other than the odd nerd with a fortune. ## At this point, I pointed out that a revenue model that depends on having illegal associates isn't really... legal. # How does my boss keep his business running and (mostly) legal without being shut down for H&S reasons? EDIT: as @shadowzee pointed out, the research might be seized during the R&D phase. My boss says that having the research happening in multiple countries might stop that, but he isn't sure. EDIT 2: There is a rumour that a lot of people think that my boss either wants to become Batman, or just sell tech that he would have used. This is not true: he wants to develop gadgets that a certain comic-book publishing company that he may or may not own significant shares in may or may not consider giving it's heroes. # Thus, rule of cool is a necessary part of the development process, as well as wow-factor. He isn't selling tazers, or bulletproof vests. He is trying to sell spider-spinners and lightsabers. [Answer] # Plausible deniability Vigilantism is illegal, but our salesman isn't selling to vigilantes, no no. He is selling self-defense equipment to concerned citizens. If you were assaulted in the street, wouldn't it be nice if you could just run away ... over the rooftops ... on Manhattan? Other equipment can also be described as self-defense. Tazers, for example, for use on feral dogs only. It is clearly printed on the box that it is not for use against humans. If a customer breaks that rule, shame on the customer. And that is not a bullet-proof suit, it is an extra sturdy motorcycling suit. Honest! Laws generally won't forbid things that haven't been invented, so he can usually get away with selling things that aren't illegal, yet. What people do with his wares is another matter. But isn't that like when somebody gets killed with a hammer? You don't go after the hammer manufacturer. Your boss probably know some lobbyists too. They can be useful in delaying any laws that would cut into his profit margin. [Answer] Your boss has a real problem in this scenario since it’s technically illegal for a person to take the law into their own hands. He or she would face legal challenges regardless of whether they sell to the good guys or the bad. — Instead I would suggest selling to the cops and other law enforcement/ civil service officials. Why not upgrade the fire fighters for example? Imagine rescue workers in flameproof mech suits rescuing people from the fires in California; or perhaps a park ranger being able to wrestle a bear rather then just shooting it. The applications are nearly limitless, but your boss should consider applications outside the normal street crime scenario. That being said, a police force in fully bullet proof mechanized tech armor being able to non-lethally subdue even the most dangerous gunmen would be pretty cool. No doubt this would go a long way to prevent a lot of the shoot-first-ask-questions-later incidents we hear about so much on the news. [Answer] You question is really similar to the problem some manufacturers in our world have to solve to stay in business. If what you sell will remove competition and thus kill the market, just make sure you supply your product to both sides, so that there will be some sort of balance of power. This has happened with nuclear bombs during cold war ([atomic secrets sold by the very persons working to develop them](https://en.wikipedia.org/wiki/Julius_and_Ethel_Rosenberg)), it happens on the weapons black market, where both sides of a conflict are supplied with weapons so that weapons merchants can thrive on the conflict. You are just going to be another actor on this stage. And, at the end of the day, when one comes into your shop asking for a super-thing, how can you tell if is a good or a bad guy? [Answer] ## This is something that is actually legal in many areas, so this does not need to be kept hidden There are a lot of places in the world where citizens are allowed to intervene in criminal activity, usually if they are witnesses of an ongoing crime or if the crime is severe. For example, many states in the US allow citizens to arrest felons if they witness the felony. Most of the types of crime heroes will be up against will probably be of this nature. ## Double-dip on the profits by selling insurance to the heroes Even though their activities may be legal, people still get dragged into court anyway, and sometimes they still get convicted even if they did not break the law. It's all about who has the better lawyers. So you hire lots of great lawyers, not only for yourself but also to back the insurance you sell to the heroes. You could even insist that your non-black-market sales must be accompanied by a hero insurance plan or you won't make the sale. ## Report on the events yourself, forming a small news group if you have to If you report on the events yourself you can provide whatever spin on the situation you need, as is often done in media anyway. Make sure you have plenty of sensational headlines about your awesome heroes. Some of your news can come in the form of social media that a billionaire should be able to push to go viral. ## Create a network to aid the heroes This part could come even before you get into the hero business so that it is already established to aid the heroes when you start those sales... Start a campaign for neighborhood safety, the "neighborhood watch" of the next generation. Make an app for mobile devices that people would want to install to help their area which helps locate crimes. It would be similar to the batman scene in that one movie (sorry, not a batman fan and don't remember which one) where batman is getting data from devices all over an area to help him track people. [Answer] You hire a boatload of lawyers along with your boatload of scientists. You spin up shadow corporations, off shore accounts, subsidiaries with subsidiaries, which buy your bankrupted other subsidiaries and take their tech for unknown purposes. You incorporate where the law is malleable and can be bought for a reasonable price. You do trial and error in lawless areas of the world, places where vigilantism is already the only law. You check in on public opinion, make minor tweaks, rinse, wash, repeat. You make sure that you are not traced back to any experiments that went poorly, while having your (also newly hired) boatload of PR people extoll the virtues of all the tech that is working out as intended. You watch out for any politicians, social organizers, or NGOs that are taking note and starting to watch you more closely. You hire private investigators and hackers to make sure they know their dirty laundry is available and could end up out in the open if they're not careful. You hire hitmen, and make inconvenient bloggers disappear. In short, you become a super villain, and eventually your own technology will be used to take you down - if the do-gooders ever figure out it is you behind the whole thing. But your boss will be too careful for that, I'm sure. Well, I'm sure he's sure -- because every super-villain has a weakness, and with a rich one like this, that weakness is usually hubris. [Answer] There's nothing stopping him putting his money into R&D. Essentially he's just joined the military-industrial complex, and become another arms dealer. What kind of R&D is he thinking of though? Pretty much every area already has people working there. Either that, or (like Boston Dynamics) it's a neat idea with no market value. So he's always going to be playing catch-up. Most new companies form round a key first product, and he hasn't got one. And then you have to actually look at whether Batman is practical. Why would you even do that? From a law enforcement PoV he's a disaster. From a military PoV he's one bullet or grenade away from just another corpse, because body armour doesn't stop everything. Rule of Cool doesn't work so well in real life. He's chosen the wrong hero anyway. The definition of a hero is someone who saves the lives of other people without hoping for reward, right? If you've got that money spare, do something good with it. No-one remembers Joseph Rowntree for what he did business-wise. Even his company name has gone, since it was bought by Nestle. But his charitable foundation continues to help people, and his name may well live forever. No-one remembers Henry Wellcome for what he did business-wise either. But the Wellcome Trust is the reason we have gene therapies today, amongst so many other advances. Again, Wellcome's name will never be forgotten. And more recently, Bill Gates. It doesn't matter whether you like what his company makes. The Bill and Melinda Gates Foundation is the reason millions of Africans will not die from diseases where the cures were well known but were not profitable for money-led medicine. In terms of lives saved, Batman doesn't even come close. [Answer] Just point to him in the direction of dictionary. > > Not one of those losers has decided to become Batman > > > "Decided to" not "are unable to". We have those "technical superpowers". Gas that can render people unconscious. Electric power that make muscles contract and people are unable to move. Hell, we even have jet powered bullets and non-lethal bullets. And for most of them (in the states) you don't need to be millionaire to have this equipment. You can go to shop and buy them. In other words your boss want to go into self-defence industry. [Answer] Well this is world-building so it's a bit ambiguous; it's only illegal if there's a law against it. And to that end I think the more widely useful your wares are the better. No one would outlaw hammers. It's a strange coincidence that the super-deluxe ultra-hammer 5000 is a great tool for robbing banks, but who would want to live in a world without hammers? Your top-of-the-line model might be a great crime-fighting kit that only millionaires can afford, but the starter model will really help out with your average Joe with his yardwork! A bit of an aside, but I don't think you have to actually deal in any shady business yourself; if bad guys want your wares they'll come up with a way to get them. You just have to make sure the product doesn't get TOO regulated and studiously point out how you follow the letter of the law. Good PR, loyal fans, and a bit of lobbying are going to help. [Answer] Move to a more evil-friendly country When bin Laden was forming al-Qaeda he didn't do this in the US or any other country with piddly things like laws. He did it in countries with weak, ineffective, extremist or corruptible governments. You don't have to look far to find countries where you could locate your research, development and production lines. Parts of Somalia aren't even really countries right now. They are often ruled by the strongest overlord of the time. Which will be you very soon after setting up shop. If the malaria and ebola become problematic for your workforce (and your bio-weapon researchers are too busy to make vaccines), you can move to any number of other countries where the government is fully corrupt. Give them a slice of the pie and enjoy immunity for as long as you keep somewhat below the radar. What you save on taxes, you pay in bribes. Your bottom line remains the same. And with the monstrous amount of profits you will have rolling in soon, buy a large block of land and develop it to western standards for your workforce. [Answer] Assuming he's in the US (and the courts are willing to uphold the 2nd Amendment), he doesn't get shut down. What are guns, pepper spray, tasers, body armor, &c but various technological superpowers? [Answer] He should just jump right in with the people who are already doing exactly this! Most of the major weapons manufacturers in the world have various "super" organizations as their primary clients. Some of these organizations (commonly referred to as "governments") are the "good guys" and some are the "bad guys" (with divisions drawn along fairly arbitrary and shifting lines) but the weapons manufacturers make a killing by selling to both sides of every conflict (though not necessarily at the same time.) These "super" organizations pay billions of dollars every year to equip hundreds of thousands of people with varying degrees of batman-like abilities as they see fit/can afford. Just like in the comic books, clashes between these heroes and villains causes fallout that often kills hundreds of thousands, if not millions of innocent bystanders, laying waste to entire cities and forcing whole populations to abandon their homes and possessions or perish. Also, just like in the comic books, this little detail gets almost completely ignored by all "right-thinking" people of the world who are just glad to see good triumph over evil yet again. Of course, for the most part these massive organizations are extremely jealous of the power they lord over the common folk, so his dreams of selling outside the bounds of recognized players that are already in the game are fraught with peril. If he tries it he'll end up with both the "heroes" and the "villains" teaming up to wipe him out. They don't like competition. You should also point out to him that the reason nobody's decided to "become Batman" on their own is that the crime rate in the developed world is actually pretty darn low in most places (compared to the more turbulent parts of our history anyway), with the exceptions being primarily certain neighbourhoods in certain cities, all of which have a distinct lack of millionaires and billionaires who would be interested in his products. So if he really wants to succeed at this he's going to have to come up with ways to market his products for people on the poorer end of the scale as well. [Answer] One important thing to be considering, Mark: you should take care to document clearly, and with plenty of witnesses, that these are all his ideas and not yours. Otherwise you could be the one who gets arrested. Or at least make sure to squirrel away some of the best tech for your own supervillain suit for when you get out of jail and take revenge. ]
[Question] [ Old Nick is Saint Nicholas' elder brother. He sees his brother's good work at Christmas and wants to help in his own way, and sees a gap in the market (he really can't compete with spreading good). # The naughty list Saint Nicholas neither punishes or rewards kids on the naughty list, but Old Nick decides that he wants to do something about that. So, he hoodwinks and bribes a few elves in the chemical factory and makes them create a [genetically-targeted virus](https://sites.google.com/site/bioterrorbible/BIO-WEAPONS/RACE-SPECIFIC-BIO-WEAPONS) that chemically sterilises bad kids. The creation of the genetic target is outside the scope of this question (suffice to say that a combination of genetic markers have been identified). The virus is harmless to and does not infect normal people. Normal people can only act as carriers in the physical sense. Now that Old Nick has a stockpile of modified [flu virus](https://en.wikipedia.org/wiki/Influenza), he's now stuck with the logistics of deployment. Santa's security measures on his reindeer barn means that Old Nick cannot steal the sleigh, he must use conventional methods. Having said that, he has the luxury of preparation time and unlimited funds. How is he able to spread the virus as quickly and widely as possible on the night of the 24th December? [Answer] # Contaminate the coal supply As is tradition, Santa gives coal to the bad children. A contaminated coal supply would allow Old Nick to use Santa's logistics to give targeted distribution of the virus and give himself the night off. [Answer] As a comment of yours states that the virus does not infect/alter normal people, we could simply modify the strain somewhat more and make it [airborne](https://en.wikipedia.org/wiki/Airborne_disease). Having done that, our vector of dispersal will be [aviation fuel](https://en.wikipedia.org/wiki/Aviation_fuel). Airplanes need loooooooads of that stuff to fly around and [the internet tells me](http://www.garfors.com/2014/06/100000-flights-day.html) there's more than 100'000 flights every 24 hours, so we'll have the thing carried anywhere in the world in sufficient time. ~~Why the fuel supply?!, you might still wonder. The answer to that lies in the facts that most planes [dump their remaining fuel](http://science.howstuffworks.com/transport/flight/modern/planes-dump-fuel-before-landing.htm) before their landing approach, so even if most of the strain does not survive the temperatures in a jet engine, some of it will be released in the air over most of the world's airports.~~ My apologies, in the heat of the moment I misread the source I quote. Fuel dumping is happening, but not nearly often enough for my scheme to work out... INSTEAD, say hello to our good old friend the [Chemtrails](https://en.wikipedia.org/wiki/Chemtrail_conspiracy_theory)! They are used for so many things already, we can just piggyback with our virus and blame the [Lizard People](http://tvtropes.org/pmwiki/pmwiki.php/Main/TheReptilians)! As airports are traffic hubs, the virus can spread from here using almost every vector your Old Nick can dream of. Merry Christmas Everyone, Ho Ho Cough... [Answer] Infect the elves If you can make the disease in a such a way that elves become carriers for the disease then every present delivered, opened or otherwise handled by Santa's little helpers will be exposed to this pathogen, and I doubt very much that elves work in a sterile environment. This also extends the reach of your virus to coal deliveries, the glittery reindeer poop that covers most of the world after a mince-pie heavy night and any child visiting a grotto. Oh, and you can use a [recent tradition](https://en.wikipedia.org/wiki/The_Elf_on_the_Shelf) to get people to literally bring the disease into their homes for direct exposure. [Answer] The best way to get total world coverage for the virus is to transport it in multiple ways so that, if one way fails, there are still other ways to get the virus out there. Firstly, I would suggest buying a ton of those drones you can get. The best easily available ones (according to Google) can fly around 25km. So if our friend Old Nick orders online a bunch of these drones complete with virus dispensers and puts them in lines with 25km gap between each drone in the line and a 1km gap between the lines the virus should get pretty comprehensive coverage. Of course the drones need controlling so Nick will need to hack into computers in each drones search area to control the drone. If there is no computer available Nick will need to order one and get someone to set it up. Nick can save some cash by not putting drones over the ocean but given we have infinite budget this doesn't really matter. His next great option is to infect the traffic system. Cars travel in all but the poorest areas so infecting cars will definitely get most people. To do this Nick should plant spores in petrol and diesel pumps around the world. The high temperatures in engines might kill the spores so Nick shouldn't put much faith in this vector. Given it's Christmas, lets make Nick a bit more festive. He could spray pine plantations with spores, although this will only get Westeners who have real trees. He can also infect the large factories that produce mince pies and/or other Christmas food. Feeding geese and turkeys viral spores might be a good idea too. Between these methods Nick should get 99% of naughty people. Keep this up every year and those bad people will soon be extinct. [Answer] Santa himself is the most reliable distribution vector, since he will visit exactly the houses we wish to target with the Naughty virus. Physical access to the sleigh itself is out; however, there are other ways to use it as a distribution platform... # Infect the Reindeer Security is likely to be far less secure on the animals than on the sleigh, simply because the animals have needs that the inanimate object does not. It should be trivial to infect them with ticks genetically engineered to act as carriers for your Naughty virus (created courtesy of some more bribed elves from Santa's bio-engineering facility); perhaps by placing them on the brushes used by the reindeer's caretakers or on the clothing of the caretakers themselves. Unless the reindeer are completely decontaminated prior to liftoff, the fleas will transfer to Santa's clothing as he interacts with the reindeer throughout the night, and from there the fleas will enter the households of all the naughty little girls and boys... Alternatively, without resorting to extra weapons development, Old Nick could simply # Infect the Wrapping Paper What's the first thing a child does when he or she gets up on Christmas Morning? That's right - run down the stairs and rip open all of the presents under the tree. Coat the inside of every roll of wrapping paper on the planet with your Anthrax spores, and when a child rips open the wrapping paper, the motion flings the spores into the air like peas being flung from a spoon catapult. Note that this method not only applies to the presents Santa distributes, but also to the [presents parents buy for their naughty children so they don't feel left out](https://worldbuilding.stackexchange.com/a/63580/27342). Of course, this is all assuming that Santa's primary security concern is protecting the billions of dollars worth of presents and the proprietary wibbly-wobbly, timey-wimey technology that allows him to store all of these goods in his sleigh and distribute them in a single trip. If he is actively guarding against bio-chemical warfare, this avenue of attack may not be open for Old Nick. [Answer] # Infect Saint Nicholas Make the pathogen airborne as well as passable through indirect contact (wrapping paper, milk glasses and cookie plates) and you got a good start. Have it be virulent enough so slightest contact is enough for infection and give Saint Nicholas the slightest case of chest cold (no where near enough to cancel, but just enough for coughing and sneezing) to help cover the room in the pathogen. On Christmas Day there will be an "extra" surprise for all as they open all the gifts Saint Nicholas handled! Saint Nick didn't visit the house with an only child that's naughty? It will still work. All the "Nice" kids on the block (or who come in contact with them) will see them soon for snow games outside or at school! [Answer] Put it on and in items that the naughty would frequently USE in their evil schemes... like lunch money, baseball bats, puppy dog tails, little sisters, flower beds, newspapers, candy, etc. Now if there was only a way to also infect internet trolls. [Answer] Use self replicating Nanobots! They could keep viral material inert in all children until a naughty detection subroutine causes them to release the virus. Since Santa is going to be visiting the entire world, drop the self replicating nanobots into the local water supplies. In order to beat the Reindeer Barn Security, Old Nick could create "trojan horse presents" that are addressed to the kiddies of Water plant employees. Another vector would be to mix the 'bots into the Jolly Old Elf's magic dust where it would be distributed kind of like a crop duster. Old Nick could insert the bots wherever the Magic Dust is created, before it ever gets to the Reindeer Barn. That said, I reeeaaallly wanna know where this little story goes :) [Answer] Riffing on the answer from `@Paul TIKI`, rather than using any virus at all just use nanobots that are programmed to cause temporary sterility as desired in the targets. This has the huge added advantage of, as also mentioned in another question, when a child is OFF the naughty list and back on the nice list, the sterility can be easily reversed. As for delivery of the nanobots, a number of the already-mentioned methods would likely do nicely, or best to use a combination. ]
[Question] [ First of all, I tried to look if this wasn't answered before. Found [this](https://worldbuilding.stackexchange.com/questions/65763/what-is-the-highest-pressure-humans-can-live-in-in-comfort) and [this](https://worldbuilding.stackexchange.com/questions/65182/what-is-the-highest-pressure-any-life-form-could-theoretically-survive-in) but neither is exactly what I need. ## Some Context There's this race of humanoid fish people. They live in cities built on the ocean floor of the planets they inhabit. For some plot reason, they decided to come to Earth. In order to remain hidden, they built their advanced post in a very deep part of the ocean floor. Their "city" is but a collection of domes with breathable air inside. But they're not made of glass - they're "force fields" that repel the water. This means that if you're inside, you can literally get out and swim (since there's nothing solid between the air and the water). Which brings us to my question. ## The Question Picture an amount of pressure that would be way more than what is necessary to kill a human being (I have no idea what this number is, so I'll just guess 1000 meters down). Given this ridiculous amount of water pressure, what would such a death look like to a bystander? For this, just imagine you're inside the dome and someone else gets thrown in the water in front of you, exposed to 1000 meters (or more) of water pressure. I want to know what happens to this guy. Does he get crushed? Bleeds from all orifices? Explodes? If you could also tell me how bad it gets with even greater depths, that would be super. If 1000 meters is too low, feel free to increase it up as much as you can, as long as it's still Earth parameters. [Answer] You would die quite instantly. L.Dutch's answer is accurate if you do the shift on a reasonably short timescale. But if you do it really fast, which I'm getting the impression is your goal, the story is a bit worse. It is true that most of the body is solid or liquid, and thus basically non-compressible. Only the air volumes will be squished. However, when you do this quickly you run into fun problems with how quickly the air can be scrunched. 1000m down means you have 100atm of pressure on you. That's 1400 pounds per square inch of your body. For a comparison, you're looking at the pressure a woman puts on stiletto heels when she strikes the floor. Your entire body will be subjected to this pressure and transfer it to the air volumes. But it can't do this instantly. It takes time. While it's happening, that pressure gradient is still an issue. Only after its done is the body pressurized enough to equalize that force. So during those first few moments, it will literally be as if a woman was driving stilletto heels into your windpipe in every direction. Tissues would accelerate inward at a speed limited only by the ability to accelerate the water into the space as the tissue is shoved towards the air pockets. I do believe the only limit to speed here is the speed of sound in water, which is quite high. Now... have you heard of water hammer? Water really doesn't like to be slowed down. So once the air pockets are gone, the water pressing in on you will keep going. Remember that water cutter from my comments? This is not going to go well. But it will be swift enough to be painless. [Answer] Pressure will act on the fluids in the body, thus gases and liquids. Liquids Well, liquids are practically non compressible, meaning that even applying large pressures they won't change in volume in an appreciable manner. So blood vessel, eyes, brain, etc. will not be severely affected. Gases Gases are contained mainly in the lungs, intestine and stomach. They will shrink to match the outer pressure (this is why when one dives after a certain depth the buoyancy is negative). The lungs are pretty spongy so the shrinking per se should not be traumatic, however it will practically nullify the exchange area, leading to suffocation. The gas contained in the intestine and the stomach will be squeezed, too, leading to the abdomen being flattened out. Since the lungs are also shrinking I suspect the bowels would move upwards pushing on the diaphragm. That's probably not as quickly lethal as the suffocation, but I am pretty sure is really painful. The eardrum will surely be perforated by the high pressure differential between the outside environment and the inner ear. In itself this is not lethal, but again it is painful. Summary Summarizing, the poor guy would die of suffocation with two perforated eardrums and flattened out bowels. Which is not a particularly spectacular way of dying, but it is rather painful. [Answer] You would find it near impossible to push someone out, let alone trow him out. To "push" 80 kg man out against 10 MPa pressure would need around 800 kJ of work and a push of 50-100 tonnes if you go head/legs first. Maybe your dome can make pockets to eject or you have special building with "airlocks" to trow him in and fill it full with water. How happy will our lucky winner be? There is 1000 tonnes of water over every square meter and water loves to hug things inside and around it and give all that love equally to every centimeter of the surface. With surface area of 1.7-1.9 square meters you will feel 1700-1900 tonnes of love. Such a warm hug will compress all gases, partially heating them up and then squeeze out of you with good measure of bodily fluids, while crushing your sternum, cracking your skull and many other bones, compacting your body in to more dense human-like brick. Show of compacting human with visuals of bubbles and cloud of bodily fluids and sounds of cracking and snapping. Near instant death, if you flood chamber fast. Speed of water flow would be 140 meters per second. If you want you could use that as water jet cutters. They won't instantly cut bones, but enough to cut and tear apart flesh like nothing. --- May as well add magical swap. If you get swapped with same volume of water. Water close to instantly squeezes you with same force as stated above. All your internal cavities with air inside will be crushed to just a fraction of their original volume. At the same time few liters of water will force their way into you. Soon compressed air will bubble out of you and water around dyed slight pink with blood from torn tissues. [Answer] As a starting point here is a video of an egg at 6,000 bar [video](https://www.youtube.com/watch?v=9S2QMQQQxFk) 1 bar is 10 meters, so we are 60,000 meters underwater. So if you look at the egg from the outside there is nothing wrong with it. The shell withstands the pressure just fine. Once the egg is cracked open all the proteins have congealed, and the egg is "cooked" but from the outside it is just fine. The same thing would happen to a human. While internally they would be crushed, with water rushing into every orifice, breaking barriers like eardrums and filling the person, from the outside they would look not very different. Unconsciousness would be instant as the brain stops functioning the moment cranial pressure hits a high mark. The water would most likely flow around the eyes past the optic nerve pushing them in long enough to stabilize the pressure. Then the probably discolored human would just sink. There would be no gasses left to keep them buoyant. Chemically they would be ruined, but physically they would not look very different. [Answer] # What would a death by extreme water pressure look like? Cort Ammon's answer is quite correct, as is Andrey's. I'll add a bit more science and some idea of visuals. * 1000 metres depth. The pressure here is about 100 atmospheres, Cort Ammon's answer applies as-is. * 10,994 metres depth. [Mariana Trench depth](https://en.wikipedia.org/wiki/Mariana_Trench). > > the water column above exerts a pressure of 1,086 bar (atmospheres)... > At this pressure, the density of water is increased by 4.96% > > > # The eyeballs would get pushed into the skull through the optic nerve channel with a pop. * 600 km depth. Pressure = 60,000 bar, the density* of the water is increased by ~ 16%* This is significant, at this point the pressure difference (59.7 tons per sq cm) and density difference from the outside to the inside of the skull (corresponding to an inrush of roughly 200 cc) is high enough that the pressure wave will implode the skull, and every other bone in the body, turning them to barely more than grit. # Essentially a faceless, barely-recognisable-as-human skin full of jelly, denatured proteins, fat and pulverised bones would gently settle downwards. Refs: <https://en.wikipedia.org/wiki/Mariana_Trench> <http://www1.lsbu.ac.uk/water/ice_vi.html> [Answer] Like all bizarre questions, the Mythbusters did this to a human analog skeleton and pig flesh. Here is the before picture. [![enter image description here](https://i.stack.imgur.com/bKkwM.png)](https://i.stack.imgur.com/bKkwM.png) Creepy, yep. But compared to what happens next, it is nothing. And here is the after picture. [![enter image description here](https://i.stack.imgur.com/hMDme.png)](https://i.stack.imgur.com/hMDme.png) Yes, that was pig flesh sealing the broken seal against the pressure gradient. Now that you have seen it, you can't unsee it. Go forth and build your world where this apparently happens to people by tossing them through an invisible barrier. [Answer] The water rushing in at high speed are a shockwave coming in all directions. You were all correct about the air cavities in your body. They won't hold-on against the pressure and the body structure would cave-in. Here is a demonstration: <https://www.youtube.com/watch?v=W4DnuQOtA8E> [Answer] A lot like this [hydrolic press crushing gummie bears](https://youtu.be/os9qYgJ6Nw8?t=34) with a side of exploding violently. If the pressure is great enough even your bones will disintegrate into dust, but either way you will end up like a non flammable underwater firework. If you want to be a total cynical person, have them take surface creatures and purposefully have them crushed by the pressure and sell tickets to see it. ]
[Question] [ I've always loved well-done ghosts. However, I've always hated the afterlife-speculation that they engender if used in a story. So I need a way to get ghosts without the fluffy spiritualistic bits. This is not a value judgement on the afterlife, I just don't want to cheapen the concept with easy answers. If we can get a purely 'materialistic' ghost, some sort of system to preserve and project the memory of a person or important event, that would make me much happier. What defines an acceptable ghost: 1. Must be perceivable, and if possible by multiple people simultaneously. 2. Must be immaterial in some sense (i.e you probably should not be able to grab it by the collar) Nonetheless, I would like my ghosts to be able to generate sound. 3. Must resemble some formerly living person in some essential aspect (visage, patterns of behavior, speech if possible). I would love it if they were partially sentient/aware and thus interactive and endowed with a deceased person's memories (at least up to a point), so they would (mis-)recognize people and could be persuaded to share their secrets. 4. This is not vital, but if they need to be killed put to rest, I would love for a way to do so. So, how do you construct a ghost? EDIT: I was asked if I wanted mere ghosts (not necessarily visible) or full-fledged apparitions (visible). If you feel you have a good answer that would necessarily render ghosts invisible, I'm listening. [Answer] All people using computer systems leave a trace of their activity. Often, this information tell a lot of important things about the personality of that person, and it could be easy for the deceased's loved ones to perceive this data as "alive", or it may just represent a way to still feel contact and have consolation for the loss. Recently, I found this moving article that may be of some inspiration: [Teenage son discovers his deceased father's ghost car in Xbox rally game](https://autos.yahoo.com/blogs/motoramic/teenage-son-discovers-his-deceased-father-s-ghost-car-in-xbox-rally-game-154558866.html) > > Well, when i was 4, my dad bought a trusty XBox. you know, the first, ruggedy, blocky one from 2001. we had tons and tons and tons of fun playing all kinds of games together - until he died, when i was just 6. > > i couldnt touch that console for 10 years. > > but once i did, i noticed something. > > we used to play a racing game, Rally Sports Challenge. actually pretty awesome for the time it came. > > and once i started meddling around... i found a GHOST. > > literaly. > > you know, when a time race happens, that the fastest lap so far gets recorded as a ghost driver? yep, you guessed it - his ghost still rolls around the track today. > > and so i played and played, and played, untill i was almost able to beat the ghost. until one day i got ahead of it, i surpassed it, and... > > i stopped right in front of the finish line, just to ensure i wouldnt delete it. > > Bliss. > > > [Answer] If you're looking for something that resembling a former human being but without there being an afterlife, then essentially you're talking about someone's imprinted consciousness remaining behind in some form. Such a thing would have no physical manifestation (because it isn't a real thing, so to say) but could still be around because other minds or objects keep it going. I´m not sure what the tech level of your story is, but the higher it gets, the easier it becomes. If we put the tech level slightly above where we are now, it becomes quite plausible. We´re already getting close, with Facebook pages for dead users that are still interacted with as an example. These people are gone, but their page lingers. If you go one step further and imagine a Facebook script that automatically replies to certain things, such as birthdays, you might get messages from dead people. In this case you still know the person is dead and you know what it is happening, but it's the first step. Any script that is smart enough to reproduce the kind of message the user would post will sound quite a bit like them. If you make the internet a bit smarter, things get more eerie. Imagine you make a picture inside your late friends home, and the face-recognition software suddenly pings his face somewhere in the corner. Of course, the software is simply pretending to be smart; it's picked up that this is your friends' home, it found a "face" that it couldn't place, and suggested that considering where you are and that there's apparently someone there with you, it must be your friend. Later on, the same kind of software might think that since your friend hasn't been talking to you in a while it will helpfully start a conversation between the two of you. Of course it's goal would be to kickstart it for a few lines before your actual friend takes over (both sides thinking the other initiated the conversation, ideally). It'll sound quite like your friend used to do, but sort of stops responding after exchanging a few platitudes. Of course the above is just software, but imagine if the software has the same response to various other people the person knew, and they start talking to each other. Human communication being what it is, something like "I talked to John yesterday" will come up. Many people will not add in "through the computer", and will instead start thinking ghosts. (Remember; people already do this). But this time, they'll have a chat history to prove it, and it'll look pretty convincing. People already use automation for a lot of common tasks and this will only expand in the future. At some point, if you die, you'll leave behind so many automated tasks, some of which are so hard to pinpoint as being automated (because if people realise it's automated, it becomes insincere, so they'll be as lifelike as possible) that it might easily be possible to get the feeling someone is still around. You'll be able to 'interact' with them, they can make sounds, generate images and even control other devices. When you add in glitches and detection faults, it gets even creepier. (Imagine the door to your friends' house going open downstairs and hearing "Welcome, John" from the automated system. It just made a false positive and when you get downstairs there'll be nobody, but you'll still get a nagging suspicion) As for putting the 'ghost' to rest; the solution would be to convince the world that this person is truly dead. This can be easy if there's a centralized register where someone's state is kept, but it can also be very difficult if various devices independently check whether or not someone is still around against each other, where the other devices automated interactions trigger the "still alive" for it, and it triggers the "still alive" for others. Such ghosts could even become angry because the scripts are picking up that you're trying to convince the world their patron is dead, even though they think he isn't. They might react less friendly, decide that your friend's logical reaction would be to deny you access to their home and things, or even alert the authorities. They might even get the idea that you are trying to kill them and become openly hostile to you. [Answer] There are two ways (that I have considered) to have physical ghosts without an afterlife, both based on strange science I only half understand. They are both crazy, but don't involve computers. 1. Parallel Universes. Parallel universes are basically (from what I understand of at least one theory) universes in which possibilities were played out differently than they were in our universe - every possibility since the beginning of time plays out results in an... abundant number of alternate universes. Those universes closest to us are the ones in which most possibilities played out the same, and only a few were different. In some of these universes a person will die, in another they live on. One could bleed through to the other, given that you can explain with some mumbo jumbo that death is a powerful event (due to the number of possibilities that end with a death, as well as energy, etc.). There are apparently [a number of people who've already thought about this](http://www.messagetoeagle.com/deathillusionparuniverse.php), though let me say here I'm not going to personally go on record and say that I think this is likely. Anyway, you could have a ghost bleeding through in an area where a person still lives there in a very similar universe, or maybe see a moment of death bleed through in a place where that possibility gets played out by that same person for every possible time that person could have died (the possibility of suicide makes this easy). But once again, all this "bleeding through to another universe" stuff makes me uncomfortable, but may work for your story. You could probably only kill this "ghost" by accessing an Parallel universe, or preventing the "bleed through" effect, whatever that is. Or just confront it and try to freak it out, seeing as it may be no less afraid of you than you are of it. My personal favorite type of ghost that could come from this is one I've often thought about after reading [The Jolly Corner](http://en.wikipedia.org/wiki/The_Jolly_Corner) by Henry James, in which the protagonist confronts an alternate version of himself who ends up advancing upon him in rage. Perhaps these two persons both existed, each in his own universe, and each was mortified by seeing the other? This is my own personal favorite explanation of the story, and not far off from what James was going for. 2. Residual energy (string theory, quantum mind). If you thought the last one was crazy, you may want to stop reading here. Given the [supposed recent evidence](http://www.sciencedaily.com/releases/2014/01/140116085105.htm) for the [quantum mind hypothesis](http://en.wikipedia.org/wiki/Quantum_mind), let us say that the mind operates above the regular scale of normal electrochemical processes - this involves quantum processes as you may have guessed from the name of the hypothesis. If the brain acts on a quantum level (this can actually play into the parallel universe idea; the position of quantum particles are a source of true randomness, leading to various possibilities within a quantum mind) then the energy left behind when a brain goes through a terrible freak-out death would probably be able to linger in some residual way (especially if you use phrases in your story like "string theory" which explain away all sorts of improbable phenomena, especially given how many different kinds of "string theory" there are) at least enough for some person to come along and detect said energy with their own brain ([brains can detect each others' signals](http://www.huffingtonpost.com/2014/11/08/brain-interface_n_6115334.html) provided a means of communicaiton) and see the horrible freak-out death. Destroying a quantum ghost would probably involve... quantum mechanics? Or maybe an [energy blast](https://www.youtube.com/watch?v=9wrEEd1ajz4#t=73). [Answer] Imagine a virus, artificial in origin, created by geneticists as an espionage tool. The virus has no physical symptoms and has a three phase life cycle. In it's first phase it is airborne and contagious; searching for a host. In the second phase it is non-contagious, quietly hiding with its host, performing its primary function. In the third phase it is again contagious, but only by touch contact with objects handled by the previous host at their moment of death. In this third phase, the virus expresses its secondary function. The primary function of the virus is to steal ideas. It slips past the blood/brain barrier and copies the host's genetically stored memories into an unused section of the virus's own genetic code. Strongly valued memories such as the faces of loved ones and those accomplishments which the host is most proud of, are reinforced within the virus by the same mechanism which reinforce suchmemories in the living mind. Having limited storage space within itself, the virus eventually only contains the hosts most valuable memories. Then it waits for the host to die. Upon the host's death, the virus enters its third phase, spreading out into any objects which are in contact with the corpse, making them vectors for its once again contagious form. The second function of the virus is to play back the stolen ideas. Once a person touches a contaminated object, the virus slowly enters them, again passing the blood/brain barrier, but this time to make a deposit rather than a withdrawal. New memories are inserted into the current moment consciousness of the new host, taking the form a indistinct sensations and half-glimpsed hallucinations. Lacking context and perhaps genetically encoded slight differently than natural memories in the new host's mind, images from the transferred memory might take on a spectral supernatural flavor. Knowledge and personality traits could also be transferred in this way, extending the illusion from that of perceiving a ghost, to one of being possessed by it as well. Originally designed to steal the insights of the greatest scientists of the age, its accidental release into the general public might make real life mimic the best actions scenes from the original GhostBusters and/or Poltergeist. Separate from this idea and each other, there are excellent scientific justifications for ghosts in both Dean Koontz's Phantoms and Piers Anthony's Shade of the Tree. [Answer] If they only have to interact with people, an idea can suffice. Consider an idea like an earworm (that cursed song someone hummed on your way into work and now it's stuck in your head). If there was a viral idea that was constantly distributing itself through a society, it might manifest in apparitions because it's the easiest way to keep itself going. That manifestation would be a ghost, and a symptom of a much larger idea spreading undetected. The advantage of being an idea is that you're already past someone's eyes and ears, so its trivial to make hallucinations. The interesting part is syncing the hallucinations up between multiple people so they see the same thing. This isn't impossible with subtle communication via. body language, but it does mean that one person shouting "you're not real! you're not real!" can really disrupt a ghost. Then again, there's no reason they couldn't also have some whisp of a form outside of our heads. Those would be the scary ones that you shout "you're not real!" and it just doesn't seem to help quite as much. [Answer] You could use ancestor simulation as a precept with multiple iterations of the same or similar simulations being run on the same ancestor simulator? Computer hard disks tend to be overwritten rather than erased - you could make this presumption of the storage or processing medium that an ancestor simulation is run on. It wouldn't be too much of a jump to make people, things and places persist in a diminished way using this as a device. Immaterial but visible could be handled by them not being included in the current simulation therefore collision detection between them and currently simulated objects does not function etc. They would be copies of people used in a previous simulation therefore could be copies of people dead in the current simulation but who were also in the previous one. This could also give them precognition if a simulation of a period was being re-run multiple times. It could also be copies of the same person. They could be killed by processes in the simulation which look out for artefacts from previous simulations and delete them. Garbage collection. Therefore, if they are aware of their status then they may be afraid of being noticed or referred to, photographed etc as this may draw the attention of the garbage collection processes. Oh dear it's all gone a bit matrixy! [Answer] TL;DR: Artificial projections based on a life's worth of digital content, partial uploading, coupled with a trigger mechanism and a durable power supply. [Uploading](http://en.wikipedia.org/wiki/Mind_uploading) never worked. It turned out that creating a new memory-association-chain in a human brain involved a holistic effort by the entire brain, and the complexity of the process defeated the best human minds for centuries on end. All it did manage to create was an abomination, a sad simile, incapable of true consciousness, of genuinely remembering new experiences, or of adapting to new environments. A failure. With time, a new practice evolved, of decorating the crypts, cemeteries and cities of the dead with these magnetic-force-field enhanced holographic projections of those no longer living, based on such partial uploads. Some were only triggered by specific actions, such as placing flowers in a particular vase in the crypt, or rippling the water in a still, crystal-clear pool, while some only activated on the anniversary of their death. The varieties were endless. As this became more accepted, and the projections were no longer seen as abominations, the practice grew in scope. After the massive blast that took out the Andromeda Gateway and the surrounding great city of Carston, surviving friends and relatives recreated a distorted, slowly evolving projected replica of the entire city and its millions of inhabitants from records of the town and of the people, all on top of the overgrown ruins. As a monument. On the [fierce battlefields](https://worldbuilding.stackexchange.com/questions/8453/massive-murderous-destruction-also-manportable) of the future, people's life-recorders sometimes survived the blast that killed their owners, and, left on the desolate and temporarily radioactive wastelands, the life-recorders triggered and released a sad and confused ghost, forever retracing their last steps and random fragments of their life. Those with [ZPE](http://en.wikipedia.org/wiki/Zero-point_energy) power-plates had a lifetime measured in tens of millennia. Slowly, as the gap between those embracing technology and those that didn't grew, the daring, the curious, the brave and the restless grew weary of Earth and embarked in [great journeys across space](https://worldbuilding.stackexchange.com/questions/9022/how-to-get-across-the-galaxy-moving-slower-than-light-in-a-single-lifetime), leaving behinds an ever-more conservative, ever regressing Earth. The [long elevators](https://worldbuilding.stackexchange.com/questions/8866/where-to-anchor-my-space-elevator) were torn off their sockets and cast out into space. Things that were once known, were forgotten. The great underground oil, coal and mineral manufacturers trudged on for millenia, undoing the depleting work of many centuries and creating [new resources for a new dawn](https://worldbuilding.stackexchange.com/questions/8716/sapience-pulsar-could-intelligence-come-in-waves). Eventually even these great machines froze in their tunnels. The ghosts, however, lived on amid the crypts and ruins of those majestic towns of an age long forgotten. [Answer] One option is akin to Solaris "copies". In short, the ghost is a production of one or more of the viewers. Create some kind of "plasma" that somehow reacts to memories of people around it. Of course, it cannot react to all memories of all people; so make it that they react to memories of certain people, or who are in a particular emotional state. Of course, being materializations of something as subjective as memories, they are subjective themselves. If the source of the memory thought the "original" was a jerk, the memory will reflect that. If the source thought it was a good man, then the materialization of the same "original" would be (and act) different. Note that all of this would not be the result of a voluntary act; the source of the memory may think that he is not who is projecting the ghost. One point is is the ghosts are interactive, or they just show the person/event as if it was a recording. If they were interactive, either the source of the memory has to witness the attempt of interaction (and then, unconsciously, think what the original person would do in the situation), or the "plasma" can communicate telepatically to transmit that information to the source. To "kill" the ghost, you could either knock the source of the memory unconscious (because it has been proven that unconscious people no longer are in the distressed state that allows for the projections), give him a drug (with or without side effects) or have a device that generates EM noise in the frequencies used by the plasma to read the source's mind. [Answer] So, by your definition, you want not just a Ghost, but an Apparition: a Ghost with visible, recognizable humanlike presence. The XBox story was my first thought, too. This could indeed be a virtual one, a recording of them as in the XBox story, or even an AI, a learning system that has acquired their skills and behaviors at least in the very specific domain in which it is designed to learn. In the XBox case, rather than merely driving like they drove on their last lap, a learning system could drive like the drove on average, displaying random of their driving quirks; or could drive as they did at their best on each stage of the race, thus driving better in sum than they ever did in life. A recorded video of someone, projected, would also work. If holograms are possible, then you have the Star Wars "Help me, Obi Wan Kenobe, you are my only hope!" - a ghost of a living person perhaps. Otherwise, you can project onto a wall, or more mysteriously, a stream of smoke, mist, cloud, or water. Could also be a computer-generated sprite texture-mapped with the person's face. Particularly with a low-fidelity projection onto a vague mist, the computer-generatedness would not be so apparent. But there are other ways to record a person's passing. Perhaps, as they walked from a clearing, they swiped at the thick leaves, and in doing so, either deliberately or accidentally hacked out a person-shaped hole, which, when the sun sets in the evening and shines through it, illuminates the spray from the waterfall. Doesn't even have to be a hole anyone's hacked out - but more likely if done as a deliberate thing. Since the sun moves slowly, you could have it so that only when the light from the sun lit a crystal at a certain angle, it refracted to become a projector - that way you could limit it only to a few minutes, or even a few seconds. One effect I've seen that caused much consternation was headlights over a hill, which, because of the angle of the road, would shine in the back of a ruined house: the house would look lived in, for a moment, and then would fall dark again as the car moved on. Headlights on hilltops have also caused any number of UFO sightings. So, they make good brief-unexplained-lightings. If a picture is briefly lit by headlights passing outside, and the figure in it appears to because the shadows cast on the picture move, that could be a convincing "ghost" effect. Lightning could have a similar effect. Another good effect is a moon-halo. Here's a good trick. When the moon is close to full and dew lies upon the grass, look at your shadow: you will be surrounded by a halo. Tell your friend "Wow, there's a halo around your shadow!" (as if you see the halo around his shadow, and not your own) and the odds of him thinking there's something mystical about himself are quite high. When you stand above a mist-covered valley, and your shadow is cast onto the mists below, that has the same effect, writ large. So in this way, someone could be convinced into thinking they see, perhaps, their own ghost, or at least an outline, with a glow from their spirit? Double-exposure is possible, too: taking shots with a film exposed some years ago that you did not know had already been used to shoot someone else, would show them as ghosts in the shots. Similarly for a videotape with an erase/record head that did not fully wipe the previous data, perhaps. For more modern digital tech, it would take some kind of software bug - or a virus/malware/joke app that would impose another character into existing video. In realtime, augmented reality apps like google goggles or yelp's equivalent, let you point your phone at things and see signs for places nearby, etc... what is there was software on your phone that meant, when you pointed your phone camera at something, you say your dead friend superimposed in the shot, or perhaps just their face overlaid over nearby faces that the camera software identified? [Answer] I should preface this with I'm not sure how much I fully accept/believe this...it's taking two philosophical theories, mashing them, and coming up with what could be a ghost. Fun anyway. If a tree falls and nobody is there to hear it, does it make a sound? My answer is no (the only exception to this fits in to the 'human-centric frame, why can't the tree observe and hear itself falling?). Without an observer the observed does not exist. This answer finds it's root's in the same theory that brings about Schrodingers cat, ultimately the observer and observed are inherently linked and cannot be separated. For example, the monitor infront of you is nothing more than a blob of matter...electrons, protons, neutrons,and a whole wide array of -rons that are quite meaningless to themselves. It is you infront of the monitor that brings them meaning, forming them into words and understanding. Two eggs on a plate with bacon can form a smiley face that you see...who says that smiley face you see is any less real than the eggs on the plate? Everything exists as a multitude of possibilities and your choice to observe it collapses it into one. The second portion of this is our shared reality. Your observation of something collapses it into a single possibility not just for you, but for me and any other observer as well. Alternate wording...you insisting that something is what it is, shapes what it is for me. It's an interesting discussion to have, and hints towards us being all fragments of the same consciousness...just take the summary of your observation can/will affect others observation If you can accept the two theories above, this does leave room for 'ghosts' as persistent interpretations...observation points that are so strong that others (you and me) can still perceive them. Left overs of past observers if you will. SO to your points...persistent observations: 1. It's perceivable to multiple people in that anyone that can perceive someone else's observation can perceive it (inability to perceive others interpretation is generally referred to as psychopathic / extreme narcissism)...so most of us. Each of us could perceive the persistent observation differently to some degree. 2. Immaterial in that they are observations, not physical 3. The persistent observation would resemble whatever someone last observed it to be...if it was a human leaving it behind, odds are it'd resemble something human. Hard to say interactive, but if it's a left behind observation point, a lot can be learned about a person from that...afterall what are we beyond what and how we observe and perceive? 4. Can't think of anything stronger and more likely to leave behind a persistent interpretation than life/death...maybe extreme repetition? [Answer] I don't understand why you want the ghosts to represent a formerly living person if you're so against the afterlife idea. That doesn't make sense to me. Regardless, I have two ideas. 1. Technology can make this happen easily. You can program your perception of a [dead] person's personality into some kind of device that uses that information and a physical picture/description of the person to create an interactive hologram. I think that's boring, though. (To kill it, turn the power off.) 2. I've always built stories off the idea that a person is comprised of four parts: the heart (emotions), the mind (logical functions), the body (duh), and the soul (beliefs). If this were true, then the body would be simply a physical vessel for the other three. So its possible, then, that you could separate the body from the others but not necessarily the others from one another. When you remove the body, what is left is your "ghost". It can have whatever appearance you (the author) wish, its intangible, it retains the logical functions of the person and can therefore determine it is a ghost, and the means of separation could be killing the body if you so wish. Given that you have creative license, you can say that the longer the ghost is separate from the body, the fuzzier its memories are. And as for killing it, any typical ghost removal methods could apply -- burn the remains, exorcism, vacuum. [Answer] The classic case of this would be the "Ghost in the Machine". An uploaded consciousness (or an AI based on a human) that exists in the internet and expresses itself into the real world from there. [Answer] It could easily be a thing the characters have a superstition or religion about, but has a technological foundation they do not understand. This gives you a lot of options. That can either be part of the plot or simply something you know yourself as the author and permit to influence the way you frame events according to the rules of the world. It can also be something that the characters are aware of, only some of them are aware of, something they are oblivious to, or something they have a revelation about later on. In my opinion the unseating of superstition, having it turn out to be something that is actually understandable once some hurdle is overcome, is a powerful storytelling device. [Answer] The possibilities are endless, i'm fond of mass hysteria since it's probably accurate. In that case the ghost is just a shared delusion created by the suggestion that it exists and being reinforced by confirmation bias. That might not seem to immediately meet your terms, however to those experiencing the shared delusion they would perceive it by attributing coincidental happenings and noises to the "ghost". For example: "Did you hear that?", "Yes, it was definitely screaming and not the wind". Immaterial? Imaginary things often are. Resemble a formerly living person? It can look and act like anything those experiencing it would like. More likely though if it did appear visibly it would be evidence of a more serious mental illness and not just a trivial trick of the mind. Killing it off? No problem, just forget about it. [Answer] Excluding using technology as your explanation since that is covered in so many other answers, you could develop a shapeshifter type of creature similar to the Clutterbumphs in Manxmouse or the Bogarts from Harry Potter. Basically, have an ethereal being (either through magic or some other means that fits in your world) that has no form of it's own and in order to manifest itself it must resemble the form of something else. Perhaps these creatures have the intent of being scary (like bogarts and clutterbumphs), or perhaps they are creatures of overwhelming sympathy that are attracted to people in mourning, etc. Perhaps they steal the image of whatever they are looking like and if someone were to inspect the corpse of whoever's image they stole, they'd find that corpse to be remarkably featureless. That's my 2 cents in any case. They are NOT the ghost (as we know it) of the thing they look like, they are themselves, but are simply formless until they can borrow the form of someone else. [Answer] One of my favorite author's did this with a really neat AU: <http://www.lemodesittjr.com/the-books/ghost-books/ghosts-columbia/> The basic idea is that a ghost is the electric/magnetic record of human consciousness. Sometimes violent deaths leave that record imprinted on an area, resulting in a visible - but intangible - ghost. There are variations where some ghosts are more "aware" than others, but most just replay specific events. He takes some other interesting turns with the story - in his world zombies are basically humans minus their "ghost" portion, they act kind of like automatons with no free will. Significant parts of the story revolve around ghost-tech - the ability to store, erase, or project ghosts (and this can also be used to zombify humans). [Answer] This is similar to what JackArbiter said in part 1 of his answer about parallel universes, but the idea of a rift of some kind between dimensions. <http://en.wikipedia.org/wiki/Interdimensional_being> What comes to mind is the old Star Trek TOS episode "The Tholian Web," where Kirk gets stuck in an "interdimensional rift." They think he is dead, and several characters see him as a ghostly apparition during the episode. <http://en.wikipedia.org/wiki/The_Tholian_Web> No religion, mysticism, or afterlife, just good ol' scientifically-questionable Star Trek. To expel the "ghost," you could heal the rift in some way, or it could naturally dissipate. [Answer] Here's how I do it. Imagine a cube, there are 3 "levels" in it. Your cube is your universe. This cube is spliced by these 3 "levels" this way: Height (top to bottom) Width (left to right) Length (front to back) The "height" is what I call "plane" (or "planes of existence") The "width" is what I call "parallel" (or "parallel worlds") The "length" is what I call "dimension" (or "different dimensions") The differences are these: Dimension = example, if your character travelled to the other dimension, he may find that the nucleus contains a neutron and electron, and the one revolving around is a positron. Different from his origin dimension (our dimension). Parallel = example, if your character moved to another parallel, he may end up in a world wherein humanity evolved from reptilians not monkeys Plane = ahh, now the sweet part. The "ghosts" that your characters are seeing are actually from a different plane than the plane your characters are in (currently). So say, someone from a "higher" (or "lower" if you prefer; this is just base on the cube analogy above), may show in his plane, and vice versa. Combine these 3, you get something like this. Character-A watched how Ghost-B opens the door to his room, then disappeared leaving the door opened. What happened was this, Ghost-B is residing on the same dimension and parallel as Character-A except that Ghost-B is on a different plane. It could be that some unexplained mystery of the universe interacted at that moment to make Ghost-B's action on his plane of existence affected the plane of Character-A. Now, if Ghost-B is on a different dimension or a different parallel, Character-A won't see Ghost-B at all. Then you can play around this setup, endless possibilities -- but is a headache at first. I'll leave the "explanation" of how and why "parallel", "dimension", and "plane" are actually 3 different realities of the multiverse. Enjoy! ]
[Question] [ On a world I am building, the day and night cycle lasts 9 years, resulting in the majority of animals migrate across the planet. One of the problems that my sapient races (one on the out going night side and one on the up coming night side) suffer is that they cannot stay in one place long enough to reliably farm. How can a species that never finds itself in one place manage to farm? [Answer] If an entire race of sapient creatures are moving, they need to take their animals, clothes, tools, houses with them. Their settlements are nomadic caravans, and the few times they get ahead of the dawn/dusk line is when they circle up and rest. They also need to carry their supplies with them. It means having tank carts with water to cross a desert/arid region, and finally, agriculture on wheels. Your races developed hydroponics or movable soil planters. The crops are not planted on the soil, they are on planters mounted on carts, and those carts are carried along with the migrating caravan. The plants are also not our regular earthen plants. These plants have evolved in this planet, and have been selectively bred by the nomads for centuries to be in this moving farm. Of course plants need more sunlight to grow. So the farming carts need to stay on the back of the caravan or the front, depending if you are follwing the dawn or dusk, respectively. The plants on the dawn side would benefit from a cool environment (as the sun is rising over frozen places) and the dusk plants would enjoy more heat (as the caravan is going into lands that were under the sun for 9 years). --- P.S.: This assumes they are nomadic and are always on the move. The actual time spent walking can vary depending on how close to the equator the caravan moves (credits to [ckersch](https://worldbuilding.stackexchange.com/users/2947/ckersch) in the question comments.) [Answer] On a planet with a 9-year day/night cycle, some plants will adapt to that cycle. They will lay down roots in the day cycle, and then die off for four and a half years, only to spring back to life when the sun comes back. Just look at how any plant copes with a cold winter environment (trees lose leaves, perenials die to the root and grow back from a bulb, etc) With trees, farming would involve cultivating and pruning trees in the sunlight, waiting for them to go dormant and lose their leaves, nomad-ing off for half a decade, then coming back when the sun returns to burst into bloom and fruit. Other plants could be grown like tulips. Tulips bulbs are planted in the fall about a month before hard frost. They stay dormant through the winter, then start growing again in the spring. I imagine a plant on your world kind of like a potato, where you plant you cuttings in a plowed field right before frost, then when you and the sun get back the plant starts growing again. If you stay in one place to protect your crops until the sun leaves, you could pick two places on opposite sides of the earth and migrate between the two every 4.5 years. I imagine that there isn't much to disturb your frozen gardens in the winter (any large destructive wildlife would have to hibernate or migrate too) so there wouldn't be much damage while you were gone. [Answer] To stay in the light, groups would farm collectively With a 9 year day/night cycle, a single group would not be able to settle down and farm a plot of land for more than a few days. Living near the equator, on an Earth-sized planet, with an Earth-length year, the nomads would need to cover an average of 7 miles/day. If they can travel 21 miles in a day of constant motion, they can stop for two days if they spend a day traveling, for for two days traveling, and so on. However, that doesn't mean that static farms can't exist, merely that a single caravan wouldn't be the sole proprietors of one. Instead, a long line of caravans would stretch out across the day side of the planet, each travelling and stopping on the same schedule. A group would spend, for example, twelve days on a farm, then pack up and travel for six days to the next farm. Each group would always do the exact same thing on each farm. Since groups would live at a certain time of day, a caravan would be responsible for a single task such as clearing land, planting crops, nurturing plants and chasing off wild animals, or harvesting crops. The harvesting groups would cache the crops they harvested, which would then go on to nourish the leading caravans the next year. Crop stores would be rationed among all of the caravans on a specific farming route, so that all groups would have food and could continue their jobs on the farms. Entire permanent villages would probably be constructed over time, with caravans moving between villages. These villages would contain store houses for crops, smithys for maintaining tools, as well as structures like schools and libraries. All of these would be public, of course, since each caravan would only live in a village for six weeks before moving on to the next. The libraries would be particularly important, since the lead caravan and the tail caravan would have no other contact with each other. Cultures, traditions, and news would be shared by writing them down and leaving them in the libraries for the other groups to read. Things like crop reports or details on how to continue things like building projects would be critically important for caravans to pass along to their successors, so all caravans would likely have dedicated librarians whose jobs it would be to read everything that groups have written down in the previous nine years and to compile reports of what their caravan did while staying at the village, before moving on. [Answer] If this planet has 4.5 years of nighttime, I can only imagine the bizarre adaptations present in its plantlife. You need to take some liberties with what the local flora is like on this planet, since you offer no details that really limit what it can look like. You mention your two groups of nomads live on the dusk line and one on the dawn line. The dusk line nomads could plant an annual crop that lies dormant on the night side and grows very vigorously on the day side (imagine really big megaflora that yields a crop worth planting 9 years in advance - it has 4.5 years of energy to grow on). They would plant these crops at their planned settlement sites along the way, advancing to the next one once night approached. I imagine the species on the day side are more active and numerous, so maybe these crops have robust defensive traits as well: huge fields of bramble surrounding the flowering part, etc. so that your nomads can be reasonably sure their crop will remain unmolested. Your dawn-line nomads have a problem: Anything they plant is going to start growing immediately and will either be consumed by wildlife during the day or, depending on your planet's temperature, will have been dormant for 4.5 years by the time they see them again. For them, you will have to establish what kind of plant life can endure the nights. Fungi, conifers, tundra vegetables, perennials with hardy rootstock that reliably fruit early in the daytime. Without further details, your dawn nomads are more likely foragers. [Answer] Some problems explaining a "roaming" agricultural subsistence strategy: Agriculture takes a lot of time to develop -- or at least it did in Earth's history. Nomadic lifestyle is simply not conducive to its development. If your planet's inhabitants had already developed agriculture before the planet went into its prolonged day and night cycle, or some plant species somehow naturally lend themselves to effectively being domesticated, that would be different, I imagine. People don't just decide to develop agriculture for the heck of it. (Sure, here on Earth people may have been experimenting around for millennia planting little things in gardens and whatnot but it wouldn't really have been "agriculture.") Nomadic subsistence patterns work for nomadic groups in no small part because of the nature of the size of the group. Those strategies don't work for larger populations that want to stay sedentary, and non-sedentary populations have no motivation to attempt them if they don't need to. Agriculture is *hard.* Some (hopefully helpful) ideas: 1. If you're envisioning that some of your native plant species require sunlight to actively thrive and others that don't, then that might make it easier to explain plant life cycles than trying to devise species that are adapted to growing during both day and night conditions. An analogy here is how plants on Earth adapted to winter conditions go dormant (the botanical equivalent of hibernating). Essentially plants would be dormant for half the cycle while others would be growing in the same location. They're not competing for nutrients because they're not active at the same time. There could even be some symbiotic relationships. Like maybe in the night cycle there's some cool nocturnal vines that grow up the trunks of the daytime-loving trees, and in the day cycle the roots or just dormant and the trees are the ones growing. 2. There are already things like cicadas here on Earth with very long life cycles. [This Wikipedia page](https://en.m.wikipedia.org/wiki/Cicada) mentions species having life cycles from 2 to 17 years long. So I suppose very protracted hibernation periods for animal/insect/etc. life could certainly be on the table. The advantage here is that you can evolve species suited to either portion of the cycle without having to hand-wave things like complicated thermoregulatory systems so much. In the end, focus on the planet in terms of itself. The things living on your world evolved under the conditions there, so perhaps the way agriculture is performed there is radically different than what we conceptualize as agriculture here. [Answer] It's not that hard, really. If people are migrating across the world, let's say it takes them 6 months. This means they can move across the entire world in 6 months, then have 4 straight years to farm. You need to find a way for this to be possible for your people to move across the world. This might be living closer to the poles (resulting in a much shorter lateral circumference than the equator) or some sort of technology (ships, trains, etc) or a smaller world. The Earth's circumference is about 24k miles, so if your people migrate they need to move ~140 miles/day if they go halfway around in six months. Even on earth this drops fairly significantly the further north you go. Similar to snowbirds who travel south for winters, your people will travel across the world. This means your people will be settled for ~4 years. Or more if you want them to have more advanced technology to allow them faster traveling. Growing certain plants in constant sunlight [is really crazy](https://gardening.stackexchange.com/q/3402/14703) and causes some earth plants to have ridiculously better yields. Some don't, however, obviously those that depend on a sunlight cycle. Depending on how earth-like you want the plants to be you could mimic earth plants behavior under constant sun or you could invent specific fauna for your world. [Answer] Is the planet roughly Earth sized? Can people circumnavigate the globe on land or are there any oceans in the way? How fast can they move? With even simple railroads, they could cover the distance between terminators in a few weeks, and, more importantly, bring a lot of harvest or farm equipment with them. How hard does the surface freeze over a 4.5-year night? This defines how close they can get to the dawn terminator before encountering ground too frozen to farm. How fast can they raise a crop? A party arriving at the frost terminator (aka thaw line, just behind the dawn terminator) would need enough food on hand to last until the first crop came in. The simplest strategy seems to be for each family or village to settle down at the frost terminator and raise as much food as possible during the nearly 4.5 years of sunlight. When overtaken by sunset, they would up stakes, migrate all the way to the frost terminator, and start over. Given about 4 years, they certainly should be able to preserve and store enough food to last through the migration and ripening of the first crop. To this simple strategy we add trade. As people spread out across the globe, the arable land becomes filled with farms and farmers, plus a constant trickle of migrants passing through on their way West from the sunset terminator to the thaw line. Now, instead of everyone individually saving food for 4 years, the farmers could help feed the migrants on the way, and stake them to enough supplies to bring in their first crops. The settled farmers would also maintain the railroads and other infrastructure, both for their own use, and to speed the migrants' passage. All this would require a great deal of trust, a sophisticated market and accounting system, and universal faith that the migrants would, in turn, become settled farmers who would work off their passage debt by maintaining the railroads and hostels, and feeding all the new migrants. When nationalism finally did arise, the territory of each country would look like two stripes, running north and south, on opposite sides of the globe. The most common aphorism for an insane, ill-advised, doomed venture would be "migrating East". The best stories written about this world will probably be about protagonists who are, in one way or another, migrating East. [Answer] Not sure if this was mentioned, but you might be able to use the plant life-cycle as a motivator for migration. Some plants don't produce a harvestable yield the first year. Fruit trees, for example, can take several years in order to grow to a size large enough to produce a crop. Perhaps your nomadic peoples have already planted (or identified existing) vegetation that is on a similar cycle as your year. They then pick and eat some, and plant others that will be ready to consume their next time around. As for the "well then why don't they just stay where the mature crops are?" question, perhaps their most fruitful production years are limited? It's your world. Everything is adjustable. Good luck! [Answer] You are describing something quite similar to [transhumance](https://en.wikipedia.org/wiki/Transhumance), which involves seasonal migration to different territories, based upon weather conditions and the needs of crops and herd animals. [Answer] It's simple what we do: After we harvest our crops, we pack up and travel towards the setting sun. As we travel, we stop at other farms, paying for our stay with some of our harvested crop. Eventually, the sun is over head, and later behind us. When the sun is almost below the horizon behind us, we begin our next year's crop. Of course, that's what we do. It's a long march - we must cover over half of the globe each season in order to be able to plant at the start of the growing season. There is another tribe that travels in the other direction, through the darkness until the sun rises again. They travel less far, but they face greater dangers. [Answer] Not really an answer, just thinking about your funny planet: It would have to be similar to Venus, rotating against its orbital motion. Venus has a temperate climate (no extreme day/night temperature differences), it's only slightly too warm. The huge jetstream in the upper atmosphere levels out day and night temperatures. Question is if a planet that has an ambient temp. of 25 (35?) degrees could maintain this jetstream and an extremely dense cloud layer and a humid, oxygen containing atmosphere. [Answer] Agriculture would start off accidental. The nomads would pick what they could as they travel and eat it on the way. As they eat it they would drop seeds, spreading those crops along their path. Containers for grain might leak, leaving a scattering of seeds behind them. As time goes on, there would be better and better food supply along one nomad's track. At some point, they may notice this and go it on purpose. They could spread or plant the seeds in the more favorable locations as they go. It is likely that morning crops and afternoon crops will be different (Noon too, if it isn't too hot). If the morning and afternoon crops are the same, then you could have two groups of nomads in the same track and that would double the benefits. Also, be aware that if there are any oceans that stretch North and South, your nomads are screwed. [Answer] With a day/night cycle of 9 years, having two cultures migrating at rotational speed, each culture is making a full circumnavigation of the globe in 9 years. Unless the planet is incredibly uniform, or the nomadic tribes incredibly new, it seems likely that there would be a kind of path which we assume both tribes would follow. A visible line of settlements. This would happen naturally due to water and shelter availability, and then over time, those would become outposts of a sort. In that scenario, each point on the trail is visited once each 4.5 years by one of the two migrating tribes. Certain plants, such as fruiting trees, could be planted by tribe A and then in 4.5 years, harvested by tribe B. That could be the basis for an interesting symbiosis. The tribes might depend on each other for survival. Each harvests for themselves, and plants for the next. Initially that could be accidental, eating apples then leaving the seeds which happen to become new trees. Later it could become intentional. [Answer] Depending on the size of the races, they might not need to, as the naturally growing plant life will already provide the food they need without farming more. If the day night cycle is 9 years (ignoring the thermodynamic problems that adds, particularly for natural plants), than they could harvest the seeds from crops and replant when they reach their next resting point. This requires that they can sit down for a year at a time to grow things. If they have to take their farming with them, the energy to move the crops will outweigh the energy they provide, allowing them to only keep small plants with them (like medical herbs). Of course, if these plants are strong enough to survive multiple 9 year revolutions, they could raise a 'wild' plot and move on, harvesting and up-keeping it when they return to that spot 9 years later. Making a plot at every rest point in their migration. ]
[Question] [ in 2015, I asked [How can a planet-spanning empire keep their soldiers experienced without wars to fight?](https://worldbuilding.stackexchange.com/questions/22669/how-can-a-planet-spanning-empire-keep-their-soldiers-experienced-without-wars-to). After doing some more thinking and mental worldbuilding based on the answers to that question, I'm currently considering having specially assigned Warzones. Literal zones hundreds of square miles in size marked on the map are explicitly designed to have actual war, but instead of 2 nations warring against each other, it's the army of the world nation split into 2 parts. Weapons are adapted so they only work in these zones unless otherwise needed, but apart from that, everything is just as lethal as in a regular, non-organized war, and both sides are encouraged to seek out new tactics and find any edge they can get. There is an agreement that interference between the world outside the warzone and the armies inside the warzone is kept to an absolute minimum, so no usage of weapons inside the warzone that may cause collateral damage outside the warzone; and no demoralizing the other faction's army by attacking civilians outside the warzone. It's not a perpetual war: every 10 years, there is one organized war lasting 6 months, but during that period, the nation is in war mode, including all the consequences to civilians outside the war zone like rationing, conscription, war bonds, war economy,... I'm not sure how this idea would work. Is it viable as it currently is? Is it viable if I change some of the numbers or details around? Does it have implementation problems that can be fixed by somewhat redesigning the war? Or are there fundamental flaws with the idea itself that prevent it from ever being viable? [Answer] This wouldn't work, not really. War has no rules. War can not have rules. See [War's just a [meta]game, son!](https://worldbuilding.stackexchange.com/q/26279/809) - Game has rules real war would not. People wouldn't go die just to train. You would need psychopaths as your flag officers. This wouldn't make a good army. And you would have serious problems recruiting. Why wouldn't these soldiers overthrow the government that tries to kill them for no reason? After all, they have the guns now, and dying in a "game" is pointless, while dying to end such games may save their sons in the future. Civilians, knowing there will be 6 months of "war", would adjust to that. No one would be surprised. No one would be strained. No one would really learn war, they would learn only how to play a game, and real war would be a shock to them. Oh, and no one would bother hiring people that can and will be taken to this "war of yours". Waste of time to train them for the job if they will be gone in few months and no one knows if they are coming back. [Answer] Won't work at all. 1.Cost Wars are massively expensive these days and will be more so in the future since autonomous warfare isn't limited to the amount of humans you have. 2.Finding Participants If you want to train something that means that you still have human soldiers. Why should they basically suicide for nothing at all? One of the major reasons that we have less and less big wars today is that people are not willing to suicide somewhere abroad for some random reason. 3. Who would fight the wars Enemy countries won't help each other to "train" their troops or help them in learning because it might be used against them. Relationships between two friendly states would take damage when your populations start to hate each other because they lost relatives. 4. It isn't even necessary As history shows, wars do a generally bad job at preparing you for the next war. The winner usually learns nothing and the loser doesn't learn much. The only problematic things wars show are those that are so problematic that it can't be overseen. If you compare WW1 and WW2 you see that in the beginning of WW2 the British and French fought the same way they did in WW1. The French had a massive defense prepared for many years of drench fights but were helpless against the German "Blitzkrieg". And because this new kind of war was successful our military tries to practice it even today. The US is fighting "Blitzkrieg" everywhere and loses them because they aren't fit to fight in partisan wars. 5. Military is a bad thing Today we still celebrate our own soldiers and think that a strong military is important. But the truth is our own military itself is our worst enemy. They are consuming a huge amount of money and resources, always have the worst solution to a problem, and are standing against every kind of modern development. Militarism is already a part of history; The last thing you want is give it another reason to try to stay. [Answer] Although you say "World nation", I think "World state" would be a better terminology here. A "World state" absolutely doesn't mean that the government has a total control over its parts. Actually we could consider even the UNO as a "world government", although its power isn't very strong. A world government can make a war to keep its army trained. For example, they can construct a wannabe-separatist region, i.e. a region which wants to depart the world government. The most simple way to do that by allowing some of the already existing separatist movements to actually take away some regions. For example, if the Spanish government would allow the ETA (Basque separatist movement) to grow until a point where they can take away [Basque Country](https://en.wikipedia.org/wiki/Basque_Country_(greater_region)) from Spain. Normally, the governments use the nation security services to destroy such movements. But, if they want a war, they can let them grow until the point after that they can be handled only by the army. From the point that the Basque Country departs Spain, the Spanish government can say that * they departed by violating the constitution * they are collecting weapons of mass destruction * they are violating basic human rights on their territory ...and many similar. Their real reason would be to train their army on the newborn army of that newborn country. A world government could do the same without any problem. I never understood why do you think that a government are all nice, idealist people. [Answer] > > Is it viable if I change some of the numbers or details around? > > > Of course. But well-trained soldiers could just be a secondary benefit, the first being a healthy military market where projects are granted, technologies are developed and the population is kept in check (if you don't support the war effort, you're the enemy.) Even better - this can work like a 'trade agreement' of sorts between high officers of opposing forces. Let's assume, say, three fictional nations: ['Oceania', 'Eurasia' and 'Eastasia.' Let's also assume the existence of a disputed area.](https://en.wikipedia.org/wiki/Nations_of_Nineteen_Eighty-Four) Whenever one of them start to get an advantage (resulting in a boost of homeland and troop morale), it purposely spread their forces thin, providing both partners with a chance for retaliation (in turn boosting their own morale.) This way some pre-filtering happens (unfit soldiers are eliminated fast), veteran units may be strategically placed to gain more experience, and everything happens in a controlled environment, to vast benefit[Citation needed] of all involved nations. [Answer] The benefit of your proposal is that it would train the soldiers to kill and be killed. The baptism of fire would be overcome before the conflict. Also it would show exactly how effective the weapons are. Now there is no statistics about how lethal gun fire actually is, as the targets would take shelter, fire back etc. The problem is though that when facing different situations against an enemy from another planet, the effectiveness may be very different. Otherwise this is simply a war rehearsal. Is it worth it? [Answer] Ok, I'll have a go. The world has about a dozen separate major armies, all listed as in sports league. One army is the reigning champion. Being a member of any of those armies is a relatively priviledged life. Enlisting as a common soldier means a substatially better life than that of a civilian blue collar job, while high ranking officers are on par with professional athletes in major sports today. Being a member of the champion team is even better. That is a life people would (literally!) kill for. Now, every once in a while, the armies compete in mock battles, fighting for practice, aquiring sponsors etc. But the position as champion can only be attained by actual mortal combat. Any team may challenge the reigning champions. The objective of the war is not known beforehand, it is revealed a time before the battle begins. Acts of heroism are awarded, acts of cowardice punished. Families of killed soldiers (esp "heroic death") are richly compensated. Survivors from the losing side might try to reassemble their army, survivors from the winning side have it made. [Answer] Military exercises exist, and it is not uncommon to train simulating the actual fight between the two teams. Of course, such training sessions attempt to reduce casualties but they already result few percents of soldiers killed while training ([source](http://www.telegraph.co.uk/news/uknews/defence/12095670/More-than-1-in-20-troop-deaths-happen-in-training.html)) anyway. Some fictional world may raise the number to 10 % or about, resulting something already close to the war. Medieval battles frequently had casualties in order of just a few percent ([source](https://history.stackexchange.com/questions/5883/how-severe-were-the-casualties-in-ancient-medieval-battles)), and [medieval tournaments](https://en.wikipedia.org/wiki/Tournament_(medieval)) had melee part that included fighting with real weapons (and was quite dangerous). [Answer] The easiest way by far is creating unrest, acting unfair, opressing independent minds, favoring a particular subpopulation without good reason, .... And then, when unrest boils over, send in the mighty army (you had to) to keep the peace (killing some along the lines and getting lots of real life training "for free"). A tyranny with an emporer on top might be a good political framework for this kind. Nobody needs to know that the leaders of the freedom fighters are secret agents of the government and that the outdated weapons they use came from the government too. One rebellion every 10 years in some part of the world that is then suppressed bloodily by the army should be doable. [Answer] Our militaries do play "war games" to promote combat readiness. However, you specify a different type of game. In your exploratory world, war games are lethal. To have such a system you would need to figure out how to convince the soldiers that it's worth dying for just a game. Perhaps you could put stakes on the games, so that at least you're just fighting a blood sport. Of course, you do have to realize that war is hell. There are no rules in war. Your job is simply to not die in an aggressive enough manner to make the other guy back down (or die trying). This leads to a complication: secrets. Most nations do not appreciate exposing their national secrets on a pseudo-battlefield. Using it in the games would simply give the opposition time to counteract it. Of course, if you just play the game without your national secrets, you're practicing a game that doesn't do a good job of modeling the real hell of war, with your real tools. One could argue martial arts are exactly the sort of thing you are looking for. Their job is to keep you ready for the worst, while simultaneously not wasting any energy on it. They strive to make everything they do beneficial in civilized life, so that it is safe to maintain those skills indefinitely until war calls on you to unlock them. All that being said, there are plenty of fictional books that create artificial blood games like this (Hunger Games comes to mind), so you can indeed build a world like this and sell it. However, you will not be basing it off of reality. Which is a good thing. I don't think anyone wants to enjoy the reality of war, in a book or otherwise. Better to romanticize it a bit. [Answer] Could you not just do a massive War Game? Using no live rounds, then that way you wouldn't need to deal with loss of life in what is basically a training exercise, but keeping everything else. [Answer] An agreement could have been made between the nations that every 10 years a war is fought for exactly 6 months. The victorious nation wins the right to a mass of either fertile land or some other oasis that is coveted for the next 10 years. The land could mean ease of living for all of its people and the wars will be fiercely fought. [Answer] ## Virtual Reality and/or immersive simulator style training. This is, in fact, one of the methods used in the modern U.S. military. There are even companies that specialize in producing such equipment: <http://ingenuity.saic.com/?cid=892> <https://www.army.mil/article/84453> <https://www.meggitttrainingsystems.com/Military/Simulation-training/FATS-M100-simulation-training-system> <http://www.army-technology.com/suppliers/sector/training-simulation/> [Answer] There is a fantastic anime movie about a similar theme, "The sky crawlers" The plot, per Wikipedia > > The Sky Crawlers is set in an alternative history timeline where > although the world is at peace, in order to ease the tension of a > populace accustomed to war and aggression, private corporations > contract fighter pilots to engage in actual combat operations against > each other. The film introduces a mystery involving characters called > Kildren (キルドレ Kirudore?, "kill-dolls") - humanoids genetically > engineered in a way that enables to live eternally in adolescence. > > > <https://en.wikipedia.org/wiki/The_Sky_Crawlers_(film)> Very much like in [https://en.wikipedia.org/wiki/The\_Truman\_Show](https://en.wikipedia.org/wiki/The_Truman_Show "The Truman Show"), this staged military conflicts are televised to the populace for entertainment. While the general populace loses fighting skill, a new breed of soldiers is eternally trained. [Answer] I am reminded somewhat of medieval tournaments, which made a certain [William the Marshal](https://en.wikipedia.org/wiki/William_Marshal,_1st_Earl_of_Pembroke) famous and rich. Back then knights were invited to attend tournaments, typically in a part of north eastern France. The objective was to be able to best, overpower, then and ransom their opponents. The intention wasn't to kill, but if it happened, it happened. These competitions were popular, and drew knights from far and wide; lured by notions of acquiring fame and wealth. William the Marshal was reported to have bested hundreds of opponents, which made him a lot of money in ransom. Presumably you could have a similar sort of thing with small teams. If, like medieval times, the suits of armour offered excellent protection, then the risk of death is low enough to encourage eager participation. If your world is high tech, it could be a great spectator sport too; what with headcams, spy drones, CCTV, GPS trackers, biosign monitors, etc. I'd say this is quite achievable, with some R&D into armoured suits. You could also combine this with making a specific sort of softer ammunition to reduce the chance of fatality. With an armoured suit, perhaps some sort of EMP round which renders the suit inoperable and thus knocks the person out (make them hostage for ransom). Something which is more achievable today would be making the bullets simply have tracking devices embedded, so even if they are made of very soft material, you'd know when they hit or come close enough to the target to knock them out. Like a digital paintballing. These techniques could be applied to larger weapon systems too. Certainly would make missile launchers less theatrical, but if the missile hits the target area you immediately are digitally tagging those who would have died in the blast area. Perhaps, like the DOTA2 International, spectators buy tickets to watch, and part of that goes to a prize fund, which combatants earn from by getting "kills" and staying alive (rather than putting the whole world into total war rationing for giggles). You could do this with bloodshed or without, but under present circumstance you'd need a dramatic cultural shift for people to accept a bloody version rather than one which features protection or electronic bullets of some description. [Answer] Michael Z. Williamson used a small scale version of this scenario as a final exam and refresher training for combat units in his fictional "[Freehold](http://www.baen.com/freehold.html) of Grainne". The combat zone was a small city, and military units were rotated through the various "sides". Grainne was a planet with a single minarchist government. The planetary population was comparable to that of the United States during the baby boom. [Answer] In the book 1984, there is a constant war between nations where the enemies and allies keep changing for no apparent reason. No one really knows what they are fighting for or against anymore. In your world nation, you could convince people of the existence of a fictional rebel nation that threatens the whole world. You can have your army from one side of the world fight your army from the other side. They won't know each other and maybe even speak incompatible languages so the farce is not found out. ]
[Question] [ ## Some background In the movie [The Wandering Earth](https://en.wikipedia.org/wiki/The_Wandering_Earth), the rotation of Earth is slowed to a stop, and then 10000 engines are strapped to one side of the planet and used to accelerate it out of the solar system. The plot also involves slingshotting around Jupiter, but this doesn't really matter for the purposes of this question. ## Other research I found a [somewhat related question](https://astronomy.stackexchange.com/questions/16457/would-we-be-able-to-feel-the-acceleration-of-a-planet-with-a-highly-eccentric-or) on Astronomy, however this deals with acceleration due to gravity. In essence it states that if a planet accelerates due to gravitational forces (e.g. an eccentric orbit around a star), everyone and everything on the planet is also being accelerated by the same source and thus the acceleration wouldn't seem to affect anything. I considered asking this question on Astronomy, however the question asking guide there seems to indicate that any hypothetical scenarios should be asked here. Similarly the Movies SE site doesn't seem like an appropriate place to ask this type of question. ## My Question If a planet was accelerating due to engines on its surface, people on the planet should (in theory) be able to feel that acceleration, since they aren't being pushed by the engines, only the planet they're on is. I would imagine that if the acceleration wasn't significant it wouldn't really be noticeable, however if this acceleration was high enough (e.g. more than 1G) then would the people on the rear side of the moving planet actually fall off? Would the atmosphere of the planet counteract some of these forces in any way or would that be stripped off the planet as well? ## Notes This question isn't about the mechanics or realism of strapping engines to a planet and moving it. I looked up a few similar questions on the site (e.g. [here](https://worldbuilding.stackexchange.com/questions/99686/the-possibility-and-possible-backlash-of-a-thruster-large-enough-to-move-a-plane) and [here](https://worldbuilding.stackexchange.com/questions/44910/how-can-i-move-a-planet)), and although they do highlight some of the possible results of doing this to a planet, they don't seem to deal with the consequences of such acceleration on everything on the planet. [Answer] # Yes Under the [equivalence principle](https://en.wikipedia.org/wiki/Equivalence_principle) anything on the "back" of the planet that wasn't strapped down would be left behind if you accelerated at >1g. > > we ... assume the complete physical equivalence of a gravitational field and a corresponding acceleration of the reference system. > — Einstein, 1907 > > > That includes people, atmosphere, water, large chunks of the planet itself. Of course as soon as you start losing mass like that your acceleration increases as you don't need so much force to move the lower mass, gravity also decreases and you start losing ever more mass ever faster. You will quite literally tear the planet apart. So don't do that, I quite like it here. [Answer] What your essentially doing is the same effect that allows you to pull a table cloth off quickly and leave everything behind. In this case, the table cloth is the Earth, and everything on it is us, water, mountains, everything. But the effects of this are even worse than that. Drag racing is the closest example I can think of. When a drag race car accelerates, the rear of the body flexes and attempts to bend underneath the front of the car. Since the metal frame is rigid and won't bend, the front lifts in response. The Earth can't shed off the energy by lifting up. So your giant engine accelerates into the planet, digging in deep. The forward facing part of the planet turns into a mushroom shape, the edges of the mushroom falling off into space and breaking apart. People on the forward side are crushed to the ground. They have a few minutes of air left and can crawl around and kiss their loved ones before it all comes to an end. The people on the back side died very quickly. The huge Earth quake from half the Earth literally compressing and moving killed everyone, shortly afterwards, their dead bodies float into space and float inside a ball of atmosphere and a trail of rocks from the edges of the Earth. The people on the sides got the most terrifying end. They were just standing there, minding their own business, when suddenly the wind grabbed them and ripped them off into space. The sheering force would rip them to shreds while they tumble through the air. It would almost feel like slow motion, people in the back would see people in front of them being torn to bits. As the Earth breaks apart, the mass reduces and the planet moves faster and faster until only the engine itself remains. With nothing guiding it, the engine would probably orbit the sun or crash into another planet. The remaining Earth rubble would likely come back together as another planet in another 100 million years. [Answer] Yes, but you could mitigate this by having a large "towing" mass near the earth in the direction of the desired motion, and as the earth moves ("falls") toward the towing mass, accelerate the towing mass away, maintaining a constant distance. If the distance was large enough, tidal forces would be minimized (ie the gravitational pull is "about the same" for all points of the earth). My completely unfounded guess would be about 0.1 AU or so. A "small" (perhaps jupiter mass sized), highly charged, black hole might work. Charged, so you could direct its motion with propusion systems that could withstand the extreme tidal forces required to propel the black hole away from the earth using electrostatic repulsion/attraction. Keeping the moon using this approach is probably out of the question given the [danse macabre](https://en.m.wikipedia.org/wiki/Danse_Macabre) that would ensue in the context of the [three-body problem](https://en.wikipedia.org/wiki/Three-body_problem). [Answer] Ultimately the answer is going to depend on how the 'engines' work and how much acceleration they produce. As the other answers (and many of the comments) have already pointed out, simply putting a bunch of rockets on one side of the planet is going to end in disaster. If they're strong enough to give even a small amount of acceleration - say 0.01G for instance, only about 3,000 times the tidal pull of the moon - then the following are likely effects: * All of the water on the planet will try to flow away from the direction of acceleration. * The atmosphere will try to do the same. * The force of the rockets pushing down on the surface will likely break it. * All structures not on the 'front' of the planet will now be braced in the wrong direction and will probably fall 'backwards'. * All life that relies on air and/or water will have to relocate to the back, where the ground is all broken and the radiant energy from the engines will kill them. * The spinning core of the planet might cause you some grief too. And that's assuming relatively small acceleration levels. Past 1G (assuming you brace the whole rear hemisphere of the planet in a big cup to stop the whole thing falling apart) all of the gas and liquid - and a fairly large portion of the solids - on the planet will no longer be on the planet, they'll be rather a large receding smudge in space. Which is OK, because well before this point the Earth at this point would be a fairly large liquid ball itself, at least half of which is dribbling over the sides of the cup. All of which is why we don't ever want to use reaction drives to move planets we're attached to. At least not quickly. If you really want to move a planet without breaking it up you need a nice large gravity well that you can manoeuvre around or manufacture at will. Since you put the `Reality Check` tag on I assume you don't want to just have magical space bending technology in your story, especially since you then have to explain why they didn't use that technology for something a bit more realistic. That brings us to the idea of using one of the gas planets of our solar system as a (very very slowly-) mobile gravity well. Larry Niven used this idea in [A World Out of Time](https://en.wikipedia.org/wiki/A_World_Out_of_Time), where a lot of laser-induced fusion rockets motors suspended in Uranus' upper atmosphere were used to move Uranus around over several decades until its gravity well passed close enough to Earth at the right time to change its orbit. The literal mechanics of it are a bit hinky, but not quite as hinky as the orbital mechanics. Which is probably why it didn't turn out all that well even in SF. But since you've put this under `Reality Check` there's not a lot of other options. Slap a Space Opera tag on it and we can give you plenty of options. Giant [spindizzy](https://en.wikipedia.org/wiki/Spindizzy) fields, selective inertial neutralisation, direct acceleration fields, temporal displacement fields (check how fast the Sun is moving through space, wait for a good moment and then jump the whole planet 3 months forward in time)... all fun ideas, none of which seem to have the least possibility of ever being real. [Answer] If you can fall off, so can everything else: air, water, soil, cars, buildings, even mountains. Gravity holds the planet together. The local effective gravity direction is always “down”. Things on Earth rely on that to make sure they stay in place. Change that to pointing up, away from the ground, and eventually everything will be moving. In other words, if you can fall off, the planetary engines will shortly no longer pushing an entire planet. ]
[Question] [ So, let us go back in time to the year 1973, specifically around October of 1973; the time frame of the Yom Kippur War. In our timeline, the conflict almost became WWIII after the Soviets threatened to intervene on behalf of Egypt after the ceasefire began to break down. After the American Sixth Fleet was deployed and DEFCON 3 was called, Egypt backed down. However, in this timeline, Egypt refuses to back down and on the 26th of October of 1973, the US Navy's Sixth Fleet and the Soviet Navy's 5th Operational Squadron face off in a naval battle 10 km off the coast of Crete after the Soviets ignore a warning shot and the Americans open fire, thinking the Soviets are preparing to attack. The 5th Operational Squadron retreats, but the Third World War has begun. As a consequence, the Soviets deploy 10,000 troops to assist Egypt, and the Americans do the same with marines, and the 82nd and 101st Airborne Divisions. However, the Soviets prepare for a fictional military operation called Operation: Red Thunderstorm; a military invasion of Europe. Around the 5th of November (a reference to V for Vendetta, just to make a fun fact), the Soviets launch an amphibious assault on Narvik to catch NATO by surprise. Two days later, the Soviets begin their push into West Germany, take West Berlin and cross the Fulda Gap, the North German Plain and the Czechoslovakian-German border simultaneously, while fighting erupts in Korea, along with Turkey, the Balkans and (for a few days) Crimea. Then on the 19th of November, NATO obliterates the Soviets with tactical nuclear weapons as they attempt to cross the Rhine River at around 9:15 AM EST. At around 11:23 AM EST, a NATO counterattack is obliterated by the Soviets also responding with tactical nuclear weapons. The next day, and one tactical nuclear exchange in Germany later, President Nixon orders a first strike against strategic locations in Eastern Europe and the USSR itself at around 10:17 AM EST, which is also the same time Britain, France and Israel launch their warheads. The Soviets then retaliate at around 10:18 AM EST. By 1:57 PM EST, the majority of the Northern Hemisphere is obliterated in nuclear fire and radiation, and the war ends with 459 million dead across the globe, and millions more injured. The problem? Would the Warsaw Pact even get close to the Rhine River? If so, would NATO realistically be able to obliterate them or let Central Europe get overrun? Feel free to provide some answers. EDIT: I want to tell you as a fun fact that I originally planned the body count to be 970 million, since I originally wanted to drag China into the war, but since they would not have time for that, that idea was scrapped. Also, to clarify: the 459 million dead is those killed in the initial attacks. I still have yet to develop the aftermath, but I am going to guess billions are going to die afterwards. gulps [Answer] My aunt and uncle were both stationed in Germany for many years as part of the US force that was ready to face the Soviets coming through the Fulda Gap. In the words of my uncle (who spent most of his time there in Tanks) they were a "speed bump". There was no way on earth that they could have stopped the Soviets in a stand up fight. They just didn't have the numbers. The USSR would have swarmed them with tactical missiles of various kinds (possibly including chemical and biological warheads) to soften them up while the mother of all dogfights eventually overwhelmed the vastly outnumbered NATO air force. Then, the real invasion would have begun. Every American tank would have been absurdly outnumbered. Based on how we performed against Soviet tanks in 1991, an American force using 1980s weapons designed specifically for the Fulda gap scenario (like the Apache, A-10, and Abrams MBT) would have done surprisingly well against a vastly larger Soviet force. Unfortunately in 1973, these weapons were not yet available and the US military had not yet completely converted to the elite all-volunteer force that wiped the floor with Saddam Hussein's military. In 1973, we were still converting over from Vietnam era weapons, equipment, and a draftee army morale problem. Given all of that, I am pretty confident that the Soviets would have easily been able to get to (and across) the Rhine. They had us beat in pretty much every single category from artillery range to airlift carrying capacity, missile payloads, you name it. Plus, they outnumbered us dramatically and the only backup the US force had were some VERY squishy European NATO allies with outdated equipment and little coordination. [Answer] Probably not. The place around Czechoslovakia borders was swarmed by nuclear mines, so if any attack would occur (and yes, there were plans for that), probably the Warszaw army would be stopped, but....Germany and Czechoslovakia would end as post-nuclear wasteland. If you are interested, you can put [this article](http://technet.idnes.cz/atomove-miny-sumava-0qa-/vojenstvi.aspx?c=A150310_104336_vojenstvi_kuz) into google translator, it is really informative about the thing. The problem is that this thing is attractive to Czech authors and not so much for english-speaking ones. I will include here some pictures from article, so you at least get the idea what waited for soviet tanks in Germany... [![Map of nuclear mines, density of them. Author: Jan Lakosil](https://i.stack.imgur.com/dThrR.jpg)](https://i.stack.imgur.com/dThrR.jpg) Map of nuclear mines, density of them per 100km2. Author: Jan Lakosil, taken from article above. As you can see, any aproaching army would have serious troubles. In that times, nuclear weapons were the main thing to use. Those mines are told to be stronger than Hiroshima bombs. For us today it is kinda unbelievable, but that's it. I will include some more articles, sadly also in Czech, but you can get some brief idea what was planned for soldiers on both sides... [Smallest nuclear hand-weapon to stop eastern soldiers](http://technet.idnes.cz/nejmensi-jaderna-zbran-davy-crockett-dse-/vojenstvi.aspx?c=A160609_140157_vojenstvi_erp) [Military drill in Czechoslovakia, 1966, for "defending" of Warszaw pact](http://technet.idnes.cz/cviceni-vltava-011-/vojenstvi.aspx?c=A140924_145651_vojenstvi_mla) - it was simulated 252 nuclear hits during the drill...THis article has nice 10 minutes video from drill, really cool to see, if you are interested. [Answer] This question hinges on the timing; the year matters quite a lot. Warsaw Pact (Soviet) and NATO (American) strategy varied over time, but we have recently declassified evidence from both sides to inform our estimations. In 1979 the USSR had planned an operation rather bluntly named "[Seven Days to the River Rhine](https://en.wikipedia.org/wiki/Seven_Days_to_the_River_Rhine)" (declassified 2005 by Polish authorities). Come the 1960s Soviet strategy became focused on a [nuclear blitzkrieg](http://nationalinterest.org/feature/the-soviet-unions-insane-plan-crush-nato-battle-13355), in which they would deploy conventional forces with nuclear weapons. In hindsight, it's not a realistic plan. Though they optimistically hoped to reach Lyon by day nine, most of their men would either be dead or struggling to survive given the fallout. It's also questionable whether Soviet soldiers would be that keen, given how obviously suicidal their missions would be. Let's assume they survive the immediate tactical nuclear bombardment. They then somehow survive the nuclear minefields mentioned in another answer. Finally they make contact with NATO and survive. By now Poland and Germany are nuclear wastelands, and not only do they have to contend with radiation sickness and survive, but their supply lines will be utterly destroyed. Infrastructure going forwards and backwards will be ruined. They'll have to scavenge for food, fuel, ammunition, amongst the rubble; against angry locals. How will they be resupplied with men and materiel? How could an offensive possibly keep going after the first few hours? There's a book called "[Inside the Soviet Army](http://militera.lib.ru/research/suvorov12/index.html)", written by a Soviet army intelligence officer who defected to Britain in the 1980s. It goes into detail on the Red Army of the 60s and 70s. He'd also written "[The Liberators](https://en.wikipedia.org/wiki/The_Liberators_(Suvorov))" about the invasion of Czechoslovakia. From his perspective, the Red Army's junior soldiers and high command were convinced they could achieve victory. Their middle ranked officers were less sure; some doubted they could beat the Bundeswehr, never mind combined NATO forces. This is owing to his view that since the end of the Second World War, Soviet military capacity had declined from a zenith, becoming corrupt to the point of uselessness. Entire divisions he said existed only on paper during peacetime, and there were widespread hardware shortages and problems with morale. There's even allegations that, in order to prevent a successful rebellion against Russian forces, Soviet engineers deliberately released subpar tanks and weapon systems to their Warsaw Pact allies, so Russian equipment would always beat them in a fight. Nonetheless, Soviet land forces would have a numerical edge, and American didn't have much of a technological lead until the 1980s; by when Soviet technology lagged behind. Soviet planners hoped for a 5:1 numerical advantage in a European offensive. Whether that deployment was feasible is another question. It may not have mattered in the end with that many tactical nuclear weapons exploding in their general direction. However, the USA did have air superiority. In 2015 the USA declassified an extensive [report on nuclear strategy from 1959](https://nsarchive.gwu.edu/nukevault/ebb538-Cold-War-Nuclear-Target-List-Declassified-First-Ever/). The bottom line is this: by then, the USA's strategy was to knock out all potential sources of Soviet nuclear delivery (at this time, aircraft rather than missiles). This plan required over 3,000 atomic bombs to be dropped over 1,000 targets in the communist bloc; regardless of whether the nations were actually at war with the USA (China was suspect as the [Sino-Soviet split](https://en.wikipedia.org/wiki/Sino-Soviet_split) hadn't happened yet). Their intention was to commit to a first strike which would stop any nuclear weapons from arriving at the continental USA. This would likely obliterate every major city from East Berlin to Beijing in every communist nation along the way. If however this did not secure victory, the bombing campaign would be extended to wipe out all military-industrial capacity. At no point in either phase are civilian casualties or friendly fire considered relevant. In conclusion, I shall quote [British Air Commodore Peter Wykeham-Barnes, Chief of Staff of Allied Air Forces in Europe](http://nationalinterest.org/blog/the-buzz/revealed-natos-cold-war-nuclear-battle-plan-would-have-13785) (1955). By '73 there were considerably more nuclear weapons about, and considerably less chance of anyone surviving long enough to achieve anything. Forget the Rhine, no one may survive the border crossing. > > “in an all-out atomic war, there would be no winners and no losers and > little left to asses,” he said. Any similar conflict would be “short > and horrible.” > > > Someone leaked details to West Germany’s Der Spiegel newspaper. > According to the leaked info, targets in West Germany had borne the > theoretical brunt of the exercise, with 268 of the 335 mock nuclear > weapons detonating inside the country. > > > Exercise officials calculated 1.7 million dead. > > > [Answer] Soviet military art in that era was essentially WWII on steroids, using masses of troops at decisive points to overwhelm the enemy (supported with "Fire corridors" laid down by mass artillery). Soviet operational art included heavy use of deception, "radio electronic combat" and special forces to confuse their enemies as to where the decisive point was actually going to be, keeping the defenders unable to mass their forces and respond to the real decisive point. While this is quite impressive on paper, the reality is that while Soviet officers were well schooled in operational art, their conscript soldiers were ill trained, undisciplined and often drunk, selling parts and supplies on the black market to make ends meet (as the logistical system was corrupt and stole their food and pay). On a larger scale, Soviet logistics were hopelessly primitive, and entire divisions were treated as "fire and forget" rounds, thrown into battle until they ran out of fuel and ammunition, whereupon a second line division would pass through the shattered remains and continue the assault. Given the shaky foundations, I suspect the Soviet military machine would score some impressive early victories as they crossed the Fula Gap, and then get bogged down as troops got lost (unable to read maps), or deserted to loot the fabulously wealthy (to them) West Germany or fell apart under timely thrusts by allied forces. I also suspect that the real killer of the Soviet army would be a partisan force which would spring up behind the lines, as West German citizens and Nato soldiers separated from their units would band together and start picking off Soviet soldiers and units, destroying roads and bridges and otherwise attacking the logistical underpinnings of the Soviet Army. While this is going on, the United States would be carrying out their WWII on Steroids plan: REFORGER. Masses of American manpower and equipment would be moving across the Atlantic to Reinforce Germany (hence REFORGER), but perhaps more likely landing in England and sharing out in preparation to make amphibious landings across Europe or the Mediterranean. We would see phase two of the conflict where depleted Soviet forces, out of fuel and ammunition attempt to retreat while facing oncoming American forces, and being sandwiched by third line Soviet forces attempting to hold their gains or expand the conquered areas. Since the second and third line forces would be using older, stockpiled equipment (some literally dating to the Second World War), encounters between American forces and Third line Soviet forces would be rather one sided, and since the Americans know logistics, their forces would be capable of continuing the fight since they would have food, fuel and ammunition. American Grand Strategy is largely Naval (since America has outlets to both major oceans), so the Soviets would also have to contend with the Pacific Fleet attacking and the Marines landing on the Soviet East coast. American Special Forces (Green Berets) would also be showing up in places like the Baltic States and Eastern Europe tormenting revolution against the Soviets as well. The wild card would be areas where the Soviets had not entered, but which would be subjected to massive Soviet PSYOPS attacks aimed and mobilizing the local Communist sympathizers and terrorist cells (like the [Red Army Faction](https://infogalactic.com/info/Red_Army_Faction)) to operate in the rear of the American forces. How effective calling on Anti American sentiment or terrorists during a hot war (especially when the news of how the Soviet Army was behaving in the occupied areas was coming out) is questionable, but probably significant enough to keep a pretty substantial rear area security force in place. The end result would be a massive "hot mess". The Soviets might actually reach the Rhine, but they would not be in any position to actually keep any gains they made, and indeed with the "Group Soviet Forces Germany" isolated and disintegrated beyond the inner German border and revolution burning across the former Warsaw Pact nations, they would probably suffer a morale and economic collapse. Western Europe would also be destroyed by the effects of combat, so a lose-lose situation all around. [Answer] [Able Archer](https://en.wikipedia.org/wiki/Able_Archer_83) ('83) was a pretty close call; while that's somewhat later than the question asks for it does give one a historical reference point. Earlier post-WWII conflicts in Hungary ('56) and Czechoslovakia ('68) are ominous enough points to extrapolate from. I for one certainly wasn't looking forward to the 50% est survival rate of an Atlantic AirSea bridge for a live REFORGER-type operation in the early '80s. However, the Soviets were already embroiled in Afghanistan by then so that means planning and buildup in the late '70s + their winning proxy in Vietnam = they went south instead of west. Remember at that time Moscow still had the Baltic states and Poland, too. (But Able Archer must have "gone apesh-t" 'cause some of the top Soviet brass thought Reagan was really gonna do it but cooler heads prevailed) I think KGB simply decided (correctly) that Western Europe wouldn't be worth it at that time. So they lost in Afghanistan, but got Crimea and Eastern Ukraine back. 'Smarter than the average Bear' Thanks @Antoine for the cool Czech films - I love the parts with the fixed bayonets (AAAARRRGGHH! death scream here) and when the BRMD hatch pops open as they start fording a river. Just "like going into Wisconsin" - *Stripes* ;-) [Answer] 1. Unlikely (in the extreme) that a bit of a navy kerfuffle would escalate to WW3. 2. 10,000 troops deployed between Oct 26 & Nov 5??? I don't think so. 2. MidEast conflict provoking an European war? Not likely. 3. How would the Soviets get to the Rhine when their supply lines were decisively eliminated? 4. Russia would be a smoking ruin, but what's the logic in the Soviets attacking Paris, for example, when the missiles are coming (mostly) from the USA (and its Navy)? 5. From what little I've read, actual soviet missile power was much inferior to what many (both in the East and in the West) claimed it to be. 6. From what little I've read, actual soviet air-power was much inferior to that in Germany and western Europe. 7. Again, why would the Soviets launch a ground attack in Europe? Their non-nuclear ground forces were overwhelmingly superior to NATO's. NATO's only effective response would have to be nuclear. So, there'd have to be some reason to believe the NATO alliance wouldn't hold. Strategically, no US president would allow the USSR to take Germany. It would be suicide. Hey, I'm neither a military buff, nor a historian, so I could be totally off-base here... I'm just questioning the roots of the scenario you mention. MidEast causing European war is unlikely. Tactical nukes triggering strategic nukes is also, imho, unlikely. ]
[Question] [ Would it be practical for a small, largely isolated country to have a drafted army to be hired out to other countries as guards for caravans or a policing force? The soldiers would all serve around 4 years, not counting training. How would this work... would the patrons pay the rulers of the country or the soldiers themselves? Is this a practical idea for a nation with fewer resources to get money? (the Country from which the mercenaries come originally is peaceful, and doesn't need a standing army beyond a small policing force.) Any ideas of what would keep an ordinary low ranked soldier loyal to the original country if he's not being paid directly? (Besides fanatical nationalism) How would this work in regards to international relationships? [Answer] This practice was done all the time in Medieval Europe, the most famous being the [Swiss Guard](https://en.wikipedia.org/wiki/Swiss_Guards) which was formed in the late 15th century and were stationed as guards in foreign courts until 1847 amendment to the Swiss Constitution outlawed all foreign military service with exception to the Pontifical Swiss Guard (The Swiss Guard that protects the Pope to this very day). The Swiss also had mercenary regiments in foreign armies and they were considered to be the best until 1515 when Germany's [Landsknechte](https://en.wikipedia.org/wiki/Landsknecht) contracted to France beat the Swiss mercenaries in the Battle of Marignano of 1515. In fact, if you're a US questioner, you should know that one of the most famous actions in the Revolutionary War was taken to defeat German Hessian Mercenaries. Washington's crossing of the Delaware and subsequent Battle of Trenton was to catch a large contingent of Hessians sleeping off a Christmas Party and was so successful, the Continental Army filled their re-enlistment commitments that were about to expire in the next week and cripple their war effort. The fact that the Hessians' recruitment by the British to such a degree that they represented 1/4 of their fighting force in the Revolutionary War was a really sore point for a lot of Colonials (From their point of view, Britain had hired Germans to kill British) that it was listed as one of the 27 grievances in the Declaration of Independence (The Revolutionary War broke out in 1775, but the Colonists weren't fighting for Independence until 1776...). The Hessians were one of, if not, the final straws that made the Colonials settle on full independence from Britain, rather than one of several other options. Edit: It should be pointed out that mercenaries were used as supplemental forces, rarely full armies. Machiavelli pointed out the ups and downs of using them, and favored that their use be carefully watched. [Answer] This sounds rather similar to the [Gurkha](https://en.wikipedia.org/wiki/Gurkha) soldiers; > > The Gurkhas or Gorkhas (/ˈɡɜːrkə, ˈɡʊər-/) with endonym Gorkhali > (Nepali: गोरखाली) are soldiers native to the Indian subcontinent of > Nepalese nationality and ethnic Nepalis of Indian nationality > recruited for the British Army, Nepalese Army, Indian Army, Gurkha > Contingent Singapore, Gurkha Reserve Unit Brunei, UN peacekeeping > force and war zones around the world. > > > As to whether it is practical depends on so many factors I cant list all of them. Personally I think the [Gurkha Contingent in Singapore](https://en.wikipedia.org/wiki/Gurkha_Contingent) is an excellent example. The Gurkha contingent has its own living area within Singapore and are prevented from integrating into the society at large due to their use as a neutral peace-keeping force. At the end of their tenure, as they are temporary, the soldiers must go back to their country. The temporary aspect is likely what keeps them loyal to their own country, and the reason many enroll to be part of the contingent is due to it being > > considered highly honorable to serve as a GC member back in Nepal > > > As well as > > The good income, their way of life, and affordable education for their children (or future children) are further draws. > > > I hope this helps and you can find much more information through the links! [Answer] The United Nations peacekeeping forces work kind of like this. Of 106,576 UN peacekeeping personnel... > > Bangladesh, Ethiopa, India, Pakistan and Rwanda currently contribute > the largest number of peacekeepers - having a share of 36 per cent of > the UN's force. The US and Russia, meanwhile, only contribute around > 70 personnel each, and the UK contributes a further 289. This takes > the total for the five permanent members of the UN Security Council to > just 4,438. These countries have significantly larger defense budgets > than the countries topping the list, although Washington pays for more > than 28 per cent of the UN peacekeeping budget. > The developing countries who donate large numbers to UN peacekeeping can use it as a source of income, helping explain their large > contributions. > > > Bold emphasis mine. <https://www.telegraph.co.uk/news/worldnews/asia/china/11898603/UN-peacekeepers-How-many-personnel-does-each-country-contribute.html> If sending your country's soldiers to work for an outside entity and getting pay in return makes them mercenaries, then these UN peacekeeping personnel are mercenaries. [Answer] It could be a system similar to the Dorsai of Gordon Dickson, which was actually based loosely on medieval Swiss practices. The Swiss were notable mercenaries through the Renaissance, getting shout outs from Machiavelli and Shakespeare. It doesn't have to be a mandatory thing for it to be an important export to the country. If being a soldier is a good way for a second or third son to get enough money for his own farm/mill/bakery/hookah parlor then there will be lines out the door. Men in their late teens/early 20s are infamous for being aggressive and short sighted. People who enjoy warring and are good at it could come back and use their earnings to recruit younger men into squads of their own. After a couple of successful campaigns, their recruits could afford to front money for recruits of their own as well as pay a percentage up. Eventually, it becomes time to retire to the simple life selling cuckoo clocks and chocolates and telling stories of that time that Tex was confused about what size coin to give the prostitute. <https://en.wikipedia.org/wiki/Swiss_mercenaries> [Answer] As hszmv mentioned, Machiavelli strongly advised against using mercenaries in his theoretical work "Il Principe" since they are in their essence unreliable. It is of course much more comfortable to pay mercenaries than to train your own troops, but in the end you can never be sure that mercenaries will actually fulfill their promise. In times of peace they will hang around and gladly take your money but when the tide turns for the worse you cannot be sure of their loyalty. They are only in it for the money, which means they can always be paid off by your enemy. And even if this does not happen, battle morale of such troops can always be expected to be worse than that of troops with family/financial/etc. ties to your realm. When a mercenary is faced with the option to either fight and possibly die or flee and take the money with him, the outcome will be the latter one in many cases. For these reasons Machiavelli stated that a good ruler should always field his own army, even though the initial investment is high. [Answer] ## Already existed and it was way more awesome than you imagine. The city state of Urbino under the rule of [Federico da Montefeltro](https://en.wikipedia.org/wiki/Federico_da_Montefeltro) in what is today Italy was famous for having the best mercenaries on the planet. Education and loyalty made them amazing, to the point eventually places started paying them preemptively just NOT to fight on the other side. They made so much money this way it supported one of the best universities in the world at the time. It worked for 3 reasons, all interrelated. 1. Federico da Montefeltro was undefeated in his entire life. 2. they were 100% honorable with contracts, if you paid them that was binding and no amount of money would change that. 3. Federico inspired amazing loyalty in his men by paying pensions, widows, orphans, and providing medical services. He was also loved by his populace. ]
[Question] [ Picture the future, where man kind has spread out across the galaxy. What would be the most precious and sought after materials? Today it is metals like gold and platinum that are most sought after. Would this still be true in the future? Am I right in thinking gold would be more abundant in space and therefore less valuable? I considered that something like antimatter or dark matter would become highly sought after, but then I discovered that apparently there is plenty of dark matter out there. Still not sure about antimatter. I have been thinking that the rarest materials in the universe would be the ones that have the most protons and neutrons - but I need someone with more knowledge on the subject to weigh in. What would be the new gold of the future? [Answer] As you say, the most sought after materials are the rarest. You also correctly assume that the rarest materials are often those with the greatest molecular mass. This is because it takes a much, much bigger star to produce heavier elements. For example, say in a sector of the universe you have 100 stars, of which: > > 80 are average sized (produce elements up to iron) > > 10 are dwarves (almost useless in terms of element production) > > 7 are massive (all elements up to lanthanum) > > 3 are supermassive (all elements) > > > All of these stars will produce helium. Not very sought after, you'll have incalculable amounts of it. 90% will produce [up to] iron. Again, not very valuable in terms of rarity. Just 10% will produce [up to] lanthanum. You're getting more valuable now. Lastly, only 3% will produce anything after that. These are the most valuable elements. 2 Therefore (in theory), in such a sector, most elements after lanthanum would be the most valued. However, in practice this would be a bit different. Let's have a look at Earth, where uranium is more common than gold, yet it's heavier so by the above definitions should be more rare. This is because the elements produced by stars in the early stages of the universe were scattered around and as such when the earth formed, it had a bit of an odd distribution of elements, and still does. --- You're right in that things like gold would be more common in space (it's rare on Earth because the Sun doesn't produce it, for the most part). So, in theory, the most valuable elements would be the heaviest. To be on the safe side, say the most valued would be after actinium, and obviously I can't say exactly which element would be most rare because of the slightly random distribution. However, if you base off these theories, you should be reasonably sure of it. However, you will also need to note that value depends not just on rarity and supply of an element, but also on demand (thanks to Philipp for bringing this up). If, for example, uranium and einsteinium are both very rare, but there is a higher demand for einsteinium, then it will be the more valuable of the two because suppliers will recognise the market and push prices up. --- As an added bonus from the comments: these will be the rarest elements, but how do we get them? As HDE says, taking a trip over to the nearest stellar remnant wouldn't be the most fun of adventures, nor would heading for a black hole to collect the remnants of a supergiant gone supernova. Fortunately, there is a solution. It lies in the way new stars and systems are created. When a star dies, it leaves behind a dwarf, neutron star, or black hole. Either of the first two are, over (very very very very long periods of) time, broken up1 and they form nebulae, the interstellar clouds from which new systems are created. The elements that end up in each planet of the system come from this cloud. So, if you visit the nebula of a past supergiant that didn't go supernova, you'll find all those lovely rare elements there. Black holes, however, may become an occupational hazard. 1: Physicists, don't batter me: I only have very limited knowledge of this process. 2: Stars will only produce elements heavier than iron at the end of their life, releasing them on supernova because they are made in the core. [Answer] If you want to stick to raw physical materials, depending if your civilization is still limited to fusion or antimatter reactors for moving about, one might guess that rare isotopes used in fusion or magnetically sealed bottles of antimatter could be valuable. But really, I think everyone is thinking a bit too much inside the box here. If you think about it, the kind of civilization that can even conceive of traveling galactic distances would not, in any significant fashion, be material-constrained. To give a simple example, consider the most used metal in the world, iron ore. The world currently produces about [3 billion metric tons of purified iron](http://minerals.usgs.gov/minerals/pubs/commodity/iron_ore/) per year, with known reserves at about 80 billion (more could be found with a more determined search). To put that in a cosmic context, a single large asteroid from the Asteroid Belt called 16 Psyche is believed to contain 17,000,000 billion tons of nickel–iron, so a single asteroid could supply the world production requirements for several million years. This holds true across all the metal groups. So the resources at our disposal are truly astronomical in size. Of course, the rate of usage could scale out as humans embark on more and more ambitious projects (compare Columbus' ship Santa Maria with a modern supertanker or nuclear aircraft carrier), but it is unlikely that the physical resources will be the main limitation. I would suggest that instead the most desired resource will be matter so arranged as to be capable of generalized problem-solving. Which is to say, matter in the form of *minds, be they squishy human brains or artificial computronium. It would make no sense to mine anything in one solar system and use up vast amounts of energy to schlep it over half-way across the galaxy. You can always find some frozen rocks to mine nearer, and millions of times cheaper. However, some brilliant live physicist, or an AI capable of amazing feats of reasoning might just justify the amazing effort it would probably take to move things across quadrillions of miles at a significant fraction of the speed of light (or somehow warp spacetime for FTL). Perhaps you don't even need to send the actual mind across, just the information. Scan the physicist, beam the relevant information over, and he gets "reincarnated" at the destination. [Answer] Yes, heavier elements will in general be more rare and thus in theory more valuable. However, at a galactic level, it matters what those elements can be used for. if all you have is a heavy metal that turns you vault into a radiation chamber, it's not that great. Things that produce great energy will be very sought after. especially things that can provide energy to a ship between stars. Solar power is great when you are near by but there is a lot of space out there. Maybe some elements will turn out to be great in alloys to help capture energy from solar winds, that would make it more valuable. Gold is pretty, safe, easy to manipulate(soft) and until fairly recently in human history only rare (not needed for more than decoration). I suspect that biological specimens are actually going to be more valuable. Whether it is a toxin or a stay young protein. And the harder it is to reproduce artificially (if at all!) the more valuable it will be. [Answer] First things first: water and food. A galactic empire would be very much like a desert empire - a hell lot of NOTHING with an oasis every once in a while. Water planets like our dear old Earth are an exception, not a rule, and without water it's currently impossible (and most likely will be very hard in the future) to grow food. So on most planets water would be imported and hauling enough water to sustain a whole city through half of a universe won't be cheap, so the water itself would be extremely expensive. Now that we've paid a small fortune to eat and drink, what do we need? Energy. In a galactic empire energy can solve pretty much any problem. Need a shelter? Create a force field. Need to go somewhere? Something has to power up your space ship. Need some item? 3D printing! Want to shot someone? Laser is your friend. So your energy source will be another valuable thing. At this point it's pretty much nothing more than a name (and maybe some plot device). Call it Uranium, Darkmatterium, Bullpooperium, whatever. What's important is that demand for it will be infinite, so no amount of supply will satisfy it, driving the prices up. The rest is a question of how you set up your world. Here on Earth raw material aren't actually that expensive - it's the processing and the middle men* driving the prices sky high. In your galactic empire both factors depend solely on your imagination. Next on the list are political issues - look up [extermination by hunger](http://en.wikipedia.org/wiki/Holodomor) to see how to create artificial scarcity. On the other hand the government may subsidy something to make everyone use it (for example to establish ubiquitous surveillance, push some company out of business, or simply to poison everyone). Last and least important are actual supply and demand. Other posters here covered supply quite well - I have nothing to add. As to demand - people in the real world aren't rational about it. Why would people in your story should behave differently? If you don't believe me go to the closest shopping centre and check out brands like Hugo Boss. You'll be shocked. Summing up - water, food and energy are essential and hard to get, because we as a species ALWAYS want more and more of it. As to the rest - you can explain any shortage or overabundance with politics and corporate interests. And I advice you to focus on that - whether we like it or not it makes more interesting story than quoting scientific statistics. [Answer] Obviously, most precious is the spice, which you can only mine on Dune, and which allows navigators to calculate hyperspace jumps. I thought you knew that. :-) Really. With advanced technologies, and different civilizations, many very rare substances can be created or grown, with very special properties. Elemental materials, which can be found around any average sun? Not very rare. [Answer] Some materials, like gold and platinum are precious only because of our history, not because its use or demand. The truth in economy is things only have value as have people willing to posses it, the demand. Precious metals have demand because they are a sort of universal currency, and giving the culture of the galactic empire anything can be precious. A not useful material, where the accumulation do not compete with the industry have some preference over needed materials, so probably gold will remain as a universal currency for humans. The leading technology of one civilization can make some artificial materials, like doped silicon, graphene, some ceramics, superconductors, quasi-crystals and its raw materials, like rare earths to be in high demand, rising its price even above gold. There are many material options demanding only a fictional technology what consume a large amount of them. As we have a universal lack of heavy elements, like rare earths, is highly probable the empire to have a big demand of a mix of them, and then high price. Unless graphene or other artificial form of a abundant element could take the place. Antimatter will be desired only if we can use in something important. As a dangerous thing, I can see a highly expensive and controlled element, like uranium today, but not a new universal standard. [Answer] The value of a material will be based on both it's utility and it's scarcity. If some substance is necessary for something like interstellar travel, it's going to become the most precious material unless it's exceedingly common (e.g. iron). Or it can be precious if its useful for life extension or something like telepathy. Scarcity may be more than just lack of abundance. Many minerals elements can be reused or reclaimed, but if something is used up everytime it is used, than that leads to more scarcity. Or maybe it's a life form (anything from a virus, or bacteria to a fully sentient being). Ultimately, Life IS the most precious thing in the Universe. A great example of all of this is from the novel Dune (Frank Herbert). The 'spice' was a special substance that granted extraordinary mental powers, from telepathy and seeing the future to "folding space" to allow interstellar travel. It was also the product of a life-form that was only found on one planet in the galaxy. Essentially, the entire galactic civilization was dependent on it. Therefore, it was the most precious substance in the universe (which made the basic plot completely unrealistic, but the concept was so powerful that its become legendary). Another example is the crystals from The Crystal Singer (Anne McCaffrey) [Answer] Everything is possible with little bit of sci-fi. But my idea is still plausible given current science knowledge and hypothesis. There is nuclear physics theory of [Island of stability](http://en.wikipedia.org/wiki/Island_of_stability) which supposes, that there should be really heavy particles with long half-live of such element. But, we were unsuccessful to find them yet. Lets say the theory is right. Lets say this particle can be (and is) used to interstellar space engine. Lets say there is region in our galaxy where exist the heaviest possible stars, and here such particle is naturally produced. Now you have some scientifically plausible (but totally not probable) material which could be mined by Galactic empire [Answer] What is sought after, is entirely dependent upon the seekers. Reasons to seek, desire, covet, or value are not universal. There is no way to predict what people will value in the future. Economics masquerades as a science when it is really an attempt to justify and fixate thought on current systems which tend to be abusive and unsustainable. Assessing the prospective trade value of the galaxy's basic elements seems to me part of that misguided way to thinking. However: Elements high on the periodic table will statistically be the rarest overall, and some might value them for that reason alone, or for their unique properties (for example, in some cases, they release more energy in reactions), but that's just one way some might decide to value them. I may be out of date on antimatter, but last I heard, we didn't know how much there was out there, and thought perhaps some entire star systems could be made entirely of anti-matter. Anti-matter could perhaps be valuable fuel if controlled anti-matter reactors were feasible and developed. The question seems to limit itself to base elements. Overall, I would think that the most useful and least common things would be healthy sustainable enjoyable ecosystems, life forms, positive culture (arts, freedom, entertainment, good company, leisure, peace, safety, justice, mental health) and useful durable technologies. [Answer] A galactic empire will have the same demands we have: energy and transport. Cheap, clean, efficient, abundant, safe energy and transport and anything that helps produce them. Why energy? It is labor saving which means more production which means more leisure time. It powers your transport and thus your economy. It lets you transform matter to reduce scarcity. Why transport? Every step of every material process involves "and then you have to move that material somewhere else". You can't have an interstellar empire without an interstellar economy and that means interstellar transport. And, let's not forget, transport means freedom and leisure. Let's take [ArtOfCode's elemental supply argument](https://worldbuilding.stackexchange.com/a/5217/760) as an example. With enough energy, you can make scarce elements through fusion and fission. As energy gets cheaper, at a certain point it becomes more economically feasible to manufacture rare and exotic elements by smashing atoms than by mining and moving them around. Speaking of mining, [Serban brings up a good point about how lucrative asteroid mining could be](https://worldbuilding.stackexchange.com/a/5227/760), but you need a lot of energy to get to the asteroid, work on it, and the transport to move them around in anything like a reasonable amount of time. Even anti-matter can be manufactured, it just takes a tremendous amount of energy. [Water and food](https://worldbuilding.stackexchange.com/a/5224/760) are excellent considerations. Water is the limiting factor for producing food. Water is easy, you either make it, extract it, or purify it; hydrogen and oxygen are everywhere, all you need is the power to do it. The Australians figured this out and now build renewable energy plants to go along with their desalination plants. Energy and transport, but the question was about materials. What sort of materials would produce cheap energy and transport in a galactic empire? I wouldn't hazard a guess, transport, material science, and energy technology advance so fast. For example, the last ten years has seen a sudden spike in demand for rare Earth minerals to make our tiny, efficient computing devices and batteries. Could that have been predicted a hundred years ago? Roll the clock back further and consider aluminum: who would have thought in Napoleon's days that [a metal once considered more precious than gold](https://en.wikipedia.org/wiki/Aluminium#History), would be so cheap and abundant that we use it for disposable cans? The best scientific minds once thought the Sun and the age of the Earth was a paradox: how could anything produce that much energy for billions of years? Then we discovered fission, and then fusion. Who knows what next? [Answer] ## Very compact or complex items, not piles of raw material I believe that in a realistic setting, any special raw materials would not be precious in any interstellar setting. For example, gold can be trivially made by any space-level civilization from lead. For us right now it's cheaper to mine existing gold than to transmute materials, but if we had a pile of gold in Alpha Centauri, then it would take more energy to transport it here than to make it locally - so the import value for gold would be zero. Without magic FTL travel, interstellar spaceships would consist of mostly fuel. If you'd be spending 99 tons of fuel for every ton of cargo, then anything that's not 100 times more valuable than spaceship fuel isn't worth transporting at all. The same goes for most items - if the destination has any available material, then it's reasonable to make everything there and transport only the bare minimum - some "bootstrapping" robots to make the machines that will make the actual product from local matter. it would be quicker to make a spaceship than to bring one that you have elsewhere, and From a trade perspective after a location has been "started, then it would make sense to transport and only very compact or unreplicable or unique items - i.e. antimatter as a compact storage of energy, sentient beings, nanobots, artwork, genetic or industrial information, or if you want to keep the means of production secret (e.g. military gear). So all of this is low-weight "parcel delivery" or transmission of information or valued data. For all other things - water, food, rocket fuel, gold, guns, uranium, spaceships - it would make sense to bring them to a place if you want to "sponsor" that place for strategic reasons, but it wouldn't make sense to have a "trade route" where you ship bulk stuff in both directions. [Answer] The most expensive elements are going to those that are rare and useful in building spaceships and habitats etc..., Niobium & Rhenium for high temperature alloys, Tungsten and Titanium for strong alloys, Indium for touch screens, Gold and Platinum as conductors, are the ones I'd be looking at first. [Answer] Some others have alluded to it, but I'll state it right out. We don't know. The most valuable material could and probably will change depending on the culture and technology of this empire, and even depending on various worlds within the empire. If you're looking for a common currency, easily portable and subdivided, I'm going to agree with some of the others and say 'energy'. Energy is always needed, everything has energy, and most things can release energy with sufficient technology. [Answer] A type III star produces high metalicity solar systems. However even with the sun being like this earth needed a oxigenation event that lasted for a couple of billion years to multiply the number of metals into the 4500 known naturaly producing metals. So it is not only the star type (metalicity) that will produce the metal richness of a solar system but the interaction with other chemical components with the existing ones in the planest created. So there could be unique precious metals (scarce) as per their use in certain planets given the unique chemistry that has taken place in each planet. [Answer] The new gold of the future? My suggestion is not material per se (it has mass, but very finite dimensionality) and is therefore easily transferrable. Let me take Adam Millers response a bit farther. Every response to this post involves energy to do work (a simple definition of energy is the ability to do work). Every sophisticated society generates or buy way of purchasing generates energy (OPEC is having hard time due to the United States' / Canada's new found oil, one of the chief concerns surrounding greenhouse gas is the cost of energy production, further second and third world nations are have trouble with climate accords due to growing industrialization which centers on energy demands). So if energy is useful across societies there would be demand from menial laborers, to starship mechanics, to painters. Demand for energy is not infinite it simply has a high limit. Every action taken by an individual or group has a finite energy requirement and a limited number of actions may be taken over time (and no E=MCˆ2 is not the exception to energy use it further reinforces the argument). Further, since there is an upward bound on the amount of energy accessible (E=MCˆ2). Energy is divisible and discrete in quantity. 8 Joules is 2 \* 4 joules is 2ˆ4 joules. Energy is complex as it can be used in most everyday process (keeping warm, keeping cool, in advanced civilizations transmuting matter). You can't forge energy, just the measurement of energy (so using a neutral parties energy measurement device is valid). Energy is also transmissable over long distances. Think of the weight even if payed in hydrogen for a multi billion dollar asteroid (I don't know the physics off hand but compressing that much gas would be a nightmare). What if you were paid in gold, food, water, or any of the other commodities mentioned: the cost of moving that much mass over 4.3 light years for your next job would be horrific. [Answer] The densest materials we can transport. In the future we will probably master e=mc2. Meaning we will have a star trek replicator like device which can make anything, but more importantly dissemble any object into energy with nearly 100% efficiency. The primary concern in the future will be energy. Everything needs it, and large ships need it even more so. The more volume an object takes the less they can transport. If you can convert any material to energy then your never out of fuel. Light elements would take more than dense ones per unit of energy. The densest materials will provide the most energy per cubic inch of space. Therefore as we advance in technology, getting closer and closer to blackholes,neutron stars, and etc make the most sense. Of course it will take magnetic confinement to keep the material from expanding as it moves away from the gravity of the blackhole or etc. The best material will expand at just the rate they consume it at so it will never get significantly bigger in volume. ]
[Question] [ I have a magical children’s fantasy land, which is bordered by mountains on its northern side. I want to make it so that anyone travelling too far north is likely to enter one of many trap pocket dimensions which are easy to walk into but extremely difficult to exit; once you’re inside, the outside edges wrap around and you find yourself back where you started if you keep travelling. This is likely to be fatal, unless the traveller happens to be in a pocket with a stream and a food supply and shelter and enough supplies to survive. Now, it’s a magical kingdom, and things don’t have to obey the laws of physics, or be 100% coherent. But I do want it to be conceptually coherent enough that I can give narrative explanations for plot events and give magical locations rules that are applied relatively consistently, locally if not globally. You could say (correctly) that I have local ad hoc physical laws specific to individual locations. So, what I’m wondering is, is there a geometry or geometric analogy that can explain/model the rules of a location where you can enter in on foot but not enter out (except at one point, if travelling in one specific direction or with a particular velocity/acceleration), while being able to continue to travel in one direction for a long time or indefinitely? EDIT: The first comment here is quite possibly a sound suggestion: A fish trap (I had the inside of a plastic bottle in mind, which I think is the same). It's easy enough to analogise the situation as, "You feel like you're walking straight ahead, but you're actually walking around the inside of the walls". The problem for me with this suggestion is that so far I don't know what using the exit looks like in-universe, as opposed to walking across the exit without actually going through it. [Answer] A children's book needs an illustrator, and that's not me. But let's try: [![enter image description here](https://i.stack.imgur.com/Y3DFk.png)](https://i.stack.imgur.com/Y3DFk.png) At the lower right (east), we have one far upper fringe of "The Normal World". It is already decidedly abnormal, because it's gotten separate from other regions east or west that go to their own, similar, traps. The person following the blue trail at bottom moves off the east edge to the west, keeps going ... eventually (question mark) notices he's going due east. The system tried to save him! Yet he persisted, going once again true north. Eventually he reaches the "hole" of the fish trap - a place where there is only a short distance east to west before you're back at yourself. Don't shoot your bow and arrow at things in the bushes or you might hit yourself! Eventually though, he's out to the point where the right side connects to the left side of the pocket world. He keeps going for some time, then turns back again south at the exclamation point -- which is justified when he reaches it again! The dotted line at the south of the pocket universe connects to the dotted line at the north. To borrow Sean O'Connor's comment -- the area on the left is the pocket, the area on the right is the distorted near pocket area, the traveller starts by the question mark and is being wrapped east to west each time he touches a green border line. But for fun, let's add a mismatch: the north edge of the wrap-around is higher. That means that "!" might actually be on a stream, down which you might take a raft until you reach your starting point again. The constant downward flow of water might be an energy source for heating the pocket dimension if the Sun never makes it there. All material eroded away simply comes back again above, so the stream never digs a canyon downward. Which is convenient for the story, since I imagine that downward must pinch inward, with less and less distance across from east to west, until there is no where left to dig down at all - your pick axe would hit itself, striking from another angle! The gravity is frozen in the shape of space, emerging from the bottom point without needing to have an actual source. The sky, however, is open - there is some "out" from this pocket dimension by going upward. Whatever you like could be up and out there. The sky is dark, and the darkness allows the landscape to radiate the heat produced by perpetual motion. Anti-solar cell photosynthesis ([not making those up!](https://www.ucdavis.edu/news/anti-solar-cells-photovoltaic-cell-works-night)) would allow plants to survive, if not necessarily thrive, under that dim sky. [Answer] ## The Hyperbolic Plane/Space Hyperbolic geometry grows exponentially with respect to radius. This means that it's very easy to get lost. Anyone who has played HyperRogue is familiar with this: the final boss is > > the challenge of back tracing a mere 100 steps accurately. It's only really feasible if the player has a way to create a trail, since there are trillions of destinations you can get to in 100 steps > > > so in a sense, the world you want already exists; it's HyperRogue. ![](https://www.roguetemple.com/z/hyper/crossroad3.png) [Answer] Spheres. [![spheres](https://i.stack.imgur.com/SgJrN.png)](https://i.stack.imgur.com/SgJrN.png) A sphere is a 3 dimensonal object. We can walk on a sphere and we will eventually wind up where we started. That is how our Earth is. In your world, other 3d spaces intersect with ours through the 4th dimension. These spaces contain spheres and humans can move around on these spheres. When 3d spaces intersect / overlap one can move from one to the other. The trick is that the intersection points are in motion through the 4th dimension. The place where they overlapped and you came thru is not there any more. The overlap might not exist, or might be somewhere different in the respective planes. Or might be with yet another 3d plane. I like the idea of the character unwittingly moving on to successively smaller spheres with the same terrain. Finally she sees someone in the distance, facing away. She shouts but the person does not turn around. She runs after the person but the person runs away, then stops when she stops. She is looking at her own back. For the childrens book, the analogy is walking off the train platform onto the train. The 3d spaces of the station and the train temporarily interect. When you are on the train and turn around the door you came through is closed. It will open again but it now connects somewhere else because the train moved. You can wait on the train until you come back around to the station they got on. Your characters will need something to orient themselves. Maybe a map like for a subway system? I could see that being an excellent cover art. Or something like a 4d compass that will show the direction of large 3d masses nearby through the 4th dimension. That will lead them to where the planes might overlap enough for them to move through to somewhere different. I am reminded of the map from Time Bandits. [![time bandits map](https://i.stack.imgur.com/BXxgJ.jpg)](https://i.stack.imgur.com/BXxgJ.jpg) <https://geektyrant.com/news/2010/3/1/must-have-time-bandits-time-portal-map.html> [Answer] Your question is a little confusing because you seem to be asking for 2 different things: * You want a dimension that is easy to enter but hard to exit * you want a dimension that wraps around itself so that you end up at your starting point after walking You also mention that you want the solution to be geometrical in nature, but I'm not sure which of those two aspects has to show up geometrically. What confuses me is that, strictly speaking, those two things are mutually exclusive. You enter from point A. If you walk 100m and walk back where started, you are back at the entrance. You can exit. So you'd need to have a "trapping corridor" after your entrance (that doesn't loop you back to the entrance), and only then, have the loop effect. I will treat of those two things separately I) For the one-way ticket thing You can not achieve that purely geometrically. As far as geometry is concerned, if you can draw a path from A to B, it is also de facto a path from B to A. To make it harder to walk one way than another, you will have to introduce other factors than pure geometry (forces, limitations of the human brain, etc..). Here are some of the most straight-forward propositions: * a slope/drop: As we said, introduce forces, cause you need to introduce something more than geometry. Gravity is a good one. Everybody loves gravity. It's just so adorable. Place a steep slope right after the entrance. Like a slide. Boom, the guy is trapped. If you wanna be extra safe, just make it a drop instead. I felt this level of complexity definitely needed an illustration: [![in case you forgot what falling is](https://i.stack.imgur.com/JV3MV.png)](https://i.stack.imgur.com/JV3MV.png) * mario kart boost pad: aka an n/p junction. It speeds you up one way but pushes you back if you try to go the other way. Put that right after your entrance [![enter image description here](https://i.stack.imgur.com/3v4En.jpg)](https://i.stack.imgur.com/3v4En.jpg) * A maze: you enter, you walk around a bit along a path, and you don't notice that there are some other paths coming from another direction that seem to connect to yours. When you turn back, you notice, and you forgot where you came from. If you like to get fancy with geometry terms, feel free to make it fractal to have plenty of branching * a door: Open it then close it. Done. More generally, any moving part in your geometry can achieve the same goal (a bridge that collapses prevents you to go back, a straight line that wraps around itself locks you in a loop, etc...) As you see, those few solutions to trap you into the dimension are not very complicated and I'm sure you could come up with a dozen more. For the other aspect, it's not much harder. II) for the self-wrapping stuff * I introduce to you, earth: Or any old sphere. Or any old variant in lower dimension like a loop. Or a cylinder. Or really any hypersurface where you can draw a self-intersecting line. If you walk in a straight line on earth and you happen to be able to walk on water (it's a good move to start a successful cult, look into it), you end up where you started * Alcohol: Give me enough of that and I promise straight lines will become a foreign notion to me. More generally, have something that trumps the senses of your victim to make them run circles * Have the exit moving: You can have just a regular plain old euclidian geometry, but if the only guide is that one shining light that is the exit, and this light happens to be moving in a circle, then you're just gonna run circles after it. If you combine any of those solutions, you have a trap that also gets you back to your starting point [Answer] If you're willing to give up "once you’re inside, the outside edges wrap around and you find yourself back where you started if you keep travelling", then you can satisfy the rest of your question's requirements by having your travelers end up in a dimension with hyperbolic geometry, which is much "bigger" in some sense than Euclidean geometry is (e.g., the circumference and area of circles both grow exponentially with radius, unlike in Euclidean geometry where they're linear and quadratic, respectively). In hyperbolic geometry, it's basically hopeless to ever end up somewhere you were before unless you retrace your steps almost exactly (you'll instead just keep ending up in new places). You can get a feel for this firsthand by downloading the game [HyperRogue](https://zenorogue.itch.io/hyperrogue) and venturing into the Haunted Woods. The only way out of that land is the way you went in, and once you're far enough in that you can't see the exit anymore, you'll find that it's basically impossible to return unless you somehow marked your path. [Answer] # Möbius strip A möbius strip is an object with just a single side. However you move over the edge,you will move along the strip on both the 'back' and 'front' of the strip to end up in the same place. An excellent example is shown here: [Möbius strip gif](https://images.prismic.io/sketchplanations/a93d784d-dd12-4ab5-b603-0401c96520a7_SP+759+Mobius+strip+-+animation.gif?auto=format&ixlib=react-9.0.3&h=1600&w=1600&q=35&dpr=3) [![strip](https://i.stack.imgur.com/HYoQ9.jpg)](https://i.stack.imgur.com/HYoQ9.jpg) By Sketchplanations There are many more complex shapes possible for such a strip, but this is the easiest way to show it. Now imagine there is one tiny strip leading to the Möbius dimension from your main dimension. Much like a fish trap you can have the entrance become smaller. Then they arrive unknowingly on the Möbius dimension. They can move around and will end up in the same place if they walk straight. There is a chance to find the tiny strip leading to and from it, but as the Möbius strip can be much wider it might be hard to stumble upon the small entrance/exit. [Answer] Anything with a preferred direction of motion will do. For example there several plant with hair on their stems: if you slide your fingers in the good direction of the hairs, you feel like a smooth velvet, but if you do in the opposite direction you will feel a spiky resistance. Those plants use those hair to make it more difficult for bug and pests to climb up their stems. Same can happen if you try to move in a cane groove: advancing in the direction where the canes are bent is way easier than advancing against the bent canes. The same concept is applied in the [anti-rape condom](https://www.cbsnews.com/news/anti-rape-condoms-picture-will-jagged-teeth-deter-world-cup-sex-assaults-rape-axe-hopes-so/), with its jagged teeth which get stuck in place when activated. So, easy to get in, it takes a surgeon to get it out. [![enter image description here](https://i.stack.imgur.com/b5txe.jpg)](https://i.stack.imgur.com/b5txe.jpg) [Answer] Your description reminds me of a wasp trap: <https://garrettwade.com/product/traditional-glass-wasp-traps> You are guided to enter in the middle of a large space, and once you wander away from the middle, it becomes very difficult to find your way back out. [Answer] It's like a circular railroad track, just in all compass directions With one inbound track. As soon as the train is on the circle, it won't ever find the way out because a train is always going forward. Yeah, it's an incomplete analogy. Trains can go backwards after all. The full story is: There's an additional direction that humans can't perceive; let's call it "feyward". Entering a circle happens if you go "feyward", to leave them you need to go "anti-feyward". Thing is, humans simply cannot go anti-feyward, just as they can't go back in time. [Answer] You don't need a place's outer edges to wrap in order to get someone trapped. As long as the place is either featureless, or of its features all look the same in all directions, people can get lost im them. Happens more than often with people in deserts and forrests. If the passage to the pocket dimension is not something you can notice with your eyes and the pocket dimension is in a forrest, even if a small one-hectare piece of woods... good luck finding your way back. Just make it so that the pocket universe is curved, and that will mean that walking in any direction will eventually lead you back to where you started. [Answer] # Equilibrium: This made me think of [stable](https://www.merriam-webster.com/dictionary/stable%20equilibrium#:%7E:text=Definition%20of%20stable%20equilibrium,original%20position%20%E2%80%94%20compare%20unstable%20equilibrium) and [unstable](https://www.merriam-webster.com/dictionary/unstable%20equilibrium) equilibrium. The equilibrium of your two universes is opposite. staying in the primary universe as you travel beyond the edge is like an unstable equilibrium - possible, but any variance from the perfect course means the path back becomes rapidly near impossible. But once inside the pocket universe, the equilibrium becomes stable as you attempt to leave - it keeps self-correcting to the default state (being in the universe), and getting out requires an extraordinary effort. [![enter image description here](https://i.stack.imgur.com/pyIDF.png)](https://i.stack.imgur.com/pyIDF.png) [Answer] # Needle in a Haystack If there are many, many interconnected pocket dimensions and they don't look very different to each other, then entering one is easy, but finding the exit is difficult since there are so many windows to other dimensions that finding the window to the correct one is difficult. I.e. it is easy to get to a different dimension, but hard to get to a specific one [Answer] An extra dimension. Humans can navigate and move in 3 dimensions. But this pocket plane is in 4 dimensions. And just like time domain, you constantly move forward in 4th dimension without any chance of going back. As a constant in 4th dimension, the door out of the plane moves away from you. In a few seconds it will be forever out of reach. Most things in this dimension moves in the 4th dimension just like you, but some things will wrap in and out just like the door. You can have mages using some magical energy to move in 4th dimension at their will. ]
[Question] [ ## Some Context I watched a generic Da-Vinci-Code-like french movie that, in a certain point, featured a secret society trying to find an item of great value that was lost in a vault built centuries ago (millenia, if I remember it correctly). Obviously, to gain access to the vault, a key is needed - since it's the only way to open it. In this type of narrative, I think that the difficulty in opening the given door, vault, chest or whatever is not in the actual "opening" of the device, but in the process of locating it. All that "it was lost in time" thing is a good explanation as to why no one has opened it before - because no one could find it - 'cause if you think about it, if anyone knew where the vault was located, they could've just blasted their way in without the need for some big search for the goddamn key. As a narrative element, I'm all for it. But in the real world, people would blow shit up. ## The Actual Question Suppose this vault exists and a certain group finds it. From an engineering point of view, would it be possible for an ancient civilization to build a contraption capable of enduring modern day attempts to break in? If yes, I would like to know what would this device be like and why dynamite, drills and general modern-day brute force should be useless against it. [Answer] Water. The misadventures on Oak Island illustrate this well. Supposedly the treasure of the Templars is there. But no-one has been able to get it. It has not been for lack of trying. <https://en.wikipedia.org/wiki/Oak_Island_mystery> > > Water in the pit: According to an account written in 1862, after > the Onslow Company had excavated to 80–90 feet (24–27 metres) the pit > flooded with seawater up to the 33-foot (10 m) level; attempts to > remove the water were unsuccessful. Explorers have made claims about > an elaborate drainage system extending from the ocean beaches to the > pit. Later treasure hunters claimed that coconut fibres were > discovered beneath the surface of a beach, Smith's Cove, in 1851. This > led to the theory that the beach had been converted into a siphon, > feeding seawater into the pit through a man-made tunnel. A sample of > this material was reportedly sent to the Smithsonian Institution > during the early 20th century, where it was concluded that the > material was coconut fibre. > > > Attempts to access the purported treasure are thwarted again and again by water. People have been killed. The water is so pernicious and so persistent that treasure hunters claim that water access is an intentional and built in part of the treasure site. You cannot blast through water. If you don't know where it is coming from, you cannot stop it. You can bail it out and you can pump it out, but the ocean has more. It is hard for humans to accomplish much when both underwater and underground. [Answer] Realistically, the only way you could make this work is by creating a scenario where forcible opening destroys the contents. All the materials that anybody had to work with in ancient times would yield with extreme speed to any kind of modern power tools. You wouldn't need dynamite, a cordless drill from Home Depot with the appropriate bit would easily handle pretty much anything anybody could have constructed prior to steel coming into common use. However, an ancient vault, by necessity, would contain ancient contents, and if you're talking about something two thousand years old made of cloth, wood, or paper, it wouldn't be difficult to come up with a scenario where exposing the contents to an abrupt pressure change from either blasting or drilling would (or could) damage or destroy what your characters were trying to acquire. EDIT: Now that I'm really thinking about it, I'm pretty sure it would only take me about three minutes to have everything in hand I could possibly need to defeat any conceivable security device using ancient materials. I wouldn't even have to put on pants. I have a pretty well-stocked garage though. [Answer] This kind of narrative really only works when your heroes are time and/or money constrained. When you only have hours to prevent doom, obtaining the key may be your only option. If, on the other hand, you have the leisure to bring modern power tools, fibre optics, ground penetrating radar or muon tomography etc. to bear, and professional mechanics and lockpicks, nothing will stop you for long. And that only holds true for the case that forceful entry would endanger the contents. If not, a packet of C4 will be faster than any key. [Answer] From a purely engineering standpoint, no. The strongest materials ancient civilizations could get their hands on would be common metals (bronze or perhaps wrought iron) or bedrock stones like granite. Modern engineers can dig, cut, or blast through either of these in pretty much unlimited quantity, though it isn't something they'd do lightly, and it wouldn't be fast or cheap. So assuming your treasure is sufficiently valuable that people will bring the full force of modern technology to bear on it - with cost being no object - it will be breached sooner or later. The solution would seem to be what AlexP suggested in comments: a vault designed such that any violent entry into it would destroy the valuable contents. In this case, a more subtle approach is required. With the right failsafes you could also resist more delicate tampering like lockpicks by making them also set off the trap. [Answer] I don't think there's any kind of enclosure the ancients (or even people nowadays) could build that would withstand persistent attempts to open with modern technology. Even something designed to destroy the contents if breached could probably be worked-around with sufficient time and resources. The obvious countermeasure is to ensure that no-one has sufficient time or resources, or that it's not cost-effective to use them. If the enclosure were in a suitably remote or hazardous environment, it might not be possible to work around it for long enough to safely breach. Extreme temperature or pressure, or some kind of hazardous material (similar to the purported rivers of Mercury in the [Mausoleum of the first Qin Emperor](https://en.wikipedia.org/wiki/Mausoleum_of_the_First_Qin_Emperor)) might do this. Locating it in Death Valley or a temple at the top of a mountain in the Himalayas may have a similar effect. [Answer] Opening the door causes the vault to collapse. Say that the doorway is composed of two giant stone doors. Right on top of them is the keystone that supports the whole ceiling. Even just nudging one of the doors open a crack shifts the keystone and collapses the ceiling, destroying everything in the vault, including potential treasure hunters. Using the key would cause supports to slide into place, preventing any collapse from happening. [Answer] Consider the following situation: Your ancient vault acts like a safety-deposit system. There are 6 boxes, each containing a separate encoded clue - one of these leads to the McGuffin you need, the others lead you on a wild goose chase at best, or possibly even hasten the encroaching doom you are trying to prevent! Different keys rotated in the lock will trigger different mechanisms, and open a different one of the boxes. Opening the boxes by force and bypassing the old lock is fairly easy with modern tools - but without the "lost-to-the-ages" key we won't know which box needs to be opened. You (probably) don't want to activate the mystical artifact of D'Uumal-U'manz instead of the amulet of Xav-Derw'Uld. [Answer] ## Deception Make people believe the treasure is hidden somewhere, preferably a large and inhospitable place, but hide it elsewhere. People are still looking for the Loch Ness monster -- not because we lack the equipment to find such a monster, but because people are not accepting "it isn't here" as an answer. Tell stories about the treasure hidden beneath an Egyptian temple (preferably without specifying which one), in the belly of a mammoth hidden in Siberia, or to be part of the treasure hoard of a Caribbean pirate, and then hide it in a pit in the Australian outback and modern humans may search for centuries, and never find it, outer than by dumb luck. But once they found the location, nothing will thwart revealing it. [Answer] Hmmm. My wife can attest that whenever we watch one of these Indiana Jones class movies, I tend to comment something to the effect, "We can't make a car that will start after sitting for 6 months. THESE guys make traps tht work 2000 years later...." Ancient mechanisms that work better depend on gravity as there mode of operation. Trigger mechanisms need to be redundant, so that if one trip stone fails the next one may work. Mechanisms should be different too. If sand friction messed up one, maybe oil lube will let the next one work. Bio poisons are plausible. Consider a very fine grinding of arsenic tri-oxide as an agent. Put a couple inches deep on the floor. Any one who stirs up the dust gets a lethal does. Dried plagues of various sorts are plausible: Anthrax is viable for 10 years in a moist pasture. How long would it last in a dry tomb? Tidal traps are another possibility: passages that flood twice a day with the rising tide, but take more than half a day to get through. Major engineering. Long passages. Consider also gas traps: Tap into a local hotspring that provides a source of H2S. Pipe that into low passages where it fills the bottom of the chamber. This is a passive system, but should catch the first few to venture into Realms of Knowledge Best Left Undiscovered. [Answer] Indiana Jones and the Last Crusade comes to mind. But remember, the Nazis weren't prepared to level the vaults: they wanted to enter sneakily and grab the powerful things from inside. I suppose it's like cryptography: any cipher can be unwound with enough brute force, but some ciphers have so much mathematical protection that it's not worth it to try. ]
[Question] [ This takes place in a magical world with a medieval setting. They've undergone an apocalypse (not defined yet, but it has no relation with necromancy) that wiped all but few thousand survivors, all permanently scarred from the tragical event that left humanity hopeless. With so many casualties and so few survivors, a few necromancers decided to use their dark art to bring back the dead to help with the rebuilding of humanity. At first, of course even the survivors shunned this act, however they began to accept the use of the undeads, and even learned simple necromancy to command the undead to help with everyday duties. A few hundred years later, necromancy had very much become a "religion". People teach and practice it everyday, even the young ones are taught necromancy - they can even resurrect dead pets! Necromancy has advanced greatly due to the unrestricted research: 1. Specific soul can be bound, but it needs the original body to find the correct soul. You can bind a random soul to a random body, though. 2. You can bind a soul to any body, but the extent of its abilities are limited to the damage it sustained, i.e skeletons cannot move at all because they don't have muscles. 3. Souls are bound indefinitely to the necromancer's will, but preserve their identities. People bringing the loved ones who just died, kids raising their old dogs, and students reanimating their excellent teacher. Because practically all people can practice necromancy, it can be concluded that at some point the world will be overpopulated (not that undeads need food, but space). How can I explain that it will never happen? UPDATE: Thanks for all the answers! So many great ideas, and I'm having difficulty which one to pick, as each one is interesting. I'm going with combining answers from [Oak](https://worldbuilding.stackexchange.com/a/84810/34288), [Paul](https://worldbuilding.stackexchange.com/a/84639/34288), [Mr. M](https://worldbuilding.stackexchange.com/a/84768/34288), and [Adwaenyth](https://worldbuilding.stackexchange.com/a/84746/34288). The mechanic I've decided I'll be using: 1. After the summon, the undead now have a physical body, and a soul body. This soul body moves the physical body (so I don't have to explain the dead brain, or if the brain or head is missing). 2. The physical body will still rot away and can be damaged. The previous rule still apply: if in process the feet go missing, for example, then it can't walk. 3. There's a "soul pool", but is unknown to the inhabitants of the world. Basically, reanimating takes a random soul from the afterlife (the pool), then binds it to the physical body. 4. There will be a fight against an (currently undecided) entity - I'm thinking of the cause of the first apocalypse, but that will be too cliche. [Answer] Your problem is impossible to limit without going too meta. Some of the suggestions while good, simply impose arbitrary limits on your necromancers. They either restrict by demanding a 1 for 1 trade (kill one human, bring back someone else) or by limiting the number of times someone can perform the art. I propose something different that gives you some freedom: As you've mentioned that the bodies stop deteriorating due to magic, perhaps make it not be the case. The "ressurected" body will not deteriorate per se, instead its "animal molecules" will slowly be replaced by magical ones. What this means is that there is effectively no deterioration noticeable. The issue comes with that the body ends up at a point where it's sustained only by magic, and as soon as the link between necromancer and "body" is broken, the magic "releases" the body, thus turning it into a pile of ash. Technically you can have overpopulation at the beggining (everyone will bring back everyone), but in practice you can only bring someone back once, because you "consume" the body when you ressurect it. [Answer] Put a limit on how many undead creatures each living person can control. When someone is at their limit and wants to create more undead, they need to release some of those they already control. Released undeads could either die immediately or lose their preservation, which means they will become feral while slowly rotting away. When a living person dies, all the undead they control get released, unless they perform some ritual which transfers control to someone else (who needs to have enough free capacity, of course). Necromancers who have more practice, better knowledge or are born with more innate talent might be able to control more undeads. [Answer] One simple solution is that which you find in games: mana. Make the use of magic a limited resource, and there you have a limit on the number of undead. More experienced/knowledgeable users can use more mana and use more undead, but are still limited. The non-undead will rot, and you won't even have that many bodies to put your magic on. `it can be concluded that at some point the world will be overpopulated` Of course this is to answer your question. But one thing that strikes me that nobody else commented yet, is on your main concern. You asked how to avoid a problem and people are telling you how to do so, but nobody commented on the problem itself. Overpopulation? Let's think about it for a minute. "`wiped all but few thousand survivors`" Earth is right now at 7 billion people, and if we migrate to sustainable means of production, we can hold much more. There are extensive parts of land with no use at all currently. So, to overpopulate, specially with beings that take space but don't need food, clothes or consume anything else, we could maybe triple that or more. Not even counting that you could keep your undead in the ocean. Assuming a world similar to earth in size and land area, and a population of only a few thousand, it would take several thousands of years to repopulate all of it and reach the current state, in terms of population. And that is assuming an non-conservative growth. Then you add a few other factors: * when someone dies, their respective undead go back to rotting until someone else takes over (Google says Maggots can consume up to 60 percent of a human body in under seven days, meaning if people don't act fast, that undead is lost forever) * plus the natural wearing out of the undeads in use * plus wars where massive numbers of undead gets destroyed Keeping the supply replenished starts to look like a challenge. Even if you don't follow any other of the suggestions here to limit the usage of necromancy and such, we're still looking at several thousands of years of having enough space for everyone, living and undead. `How can I explain that it will never happen?` When you take into account all those factors, they don't explain that it will "never happen", but for sure it is not a problem to be worried about for uncountable generations (more than 100 for sure). And if the world is medieval, they will most probably evolve their technologies quite a lot, very fast. Specially with so much free labor. It's very feasible they will reach the space age in less than 2 millenia. Maybe ask yourself how relevant to your story it is to worry about that at this point. ;-) Note to self: a civilization with space exploration technology and necromancy. Sounds original, this idea can go somewhere. X-D [Answer] You could solve the problem if you are open to some wiggle room on your 4th point: The undead body is preserved by magic. If the undead body doesn't regenerate from all damage or that regeneration has a cost for the summoner, then the oldest or most hard used corpses would eventually be unable to function or might simply be not worth repairing compared to replacing it with fresher specimens. [Answer] Well in the best stories that involve magic, there is always a cost or a catch to the use of magic. That is where your mechanism for not being over-run by zombies lies. 1. Have the dead being bound to a body, even their own original body, something that the dead don't really want. They want to rest, so that each day is a test of wills. Maybe make it easier if it's a close family member in a loving relationship. The results don't have to be violent or gruesome, but if the soul wins, the corpse just collapses. This kind of breaks number 3 in the list, but that rule makes necromancy way too powerful. 2. A soul that has won it's freedom from binding can not be bound again. 3. The longer someone is dead, the harder it is to bind their souls. 4. There is no guarantee that the dead will inhabit a body peacefully. In the process of binding, the departed may want to strike at the necromancer, creating a chance of insanity. 5. The higher order a creature, the harder it is to reanimate. A kid can bring back a goldfish, a teenager the family cat. A twenty year old can bring back the Dog. Talent and natural ability can help with this as well. Only the really skilled can raise and maintain more than 6 or 7 undead at a time. Fill your asylums with those who tried to bind the wrong soul to a body. Maybe do away with the total preservation of the corpse and simply have it last twice as long. These are some example rules you can impose. Introduce some risk and cost to the power to keep it from getting out of hand. [Answer] # Kill off the living I'd base myself on the World Of Stone from the [Death Gate Cycle](https://en.wikipedia.org/wiki/The_Death_Gate_Cycle#Abarrach.2C_the_world_of_stone) by Weiss and Hickman. Basically, reviving someone also requires someone else to die. Since you can make your actual world bigger than the known world to your characters, they don't have to notice a one-on-one connection. Reviving someone in Magical Midieval London can kill someone in Magical But Not Yet Necromancy-Converted South-America. The few people that do die in the near vicinity of the necromancers, could look like they've been hit by a mysterious disease. They would just be resurrected anyway. By the time the people find out, they might be too dependent on necromancy already. At that point you might rest assured that someone decides that a few deaths on the other side of the world are acceptable in return for cheap labor. The working class and their unions are a bother anyway, no? Of course, this might require you to change the way your magic works, which may or may not be allowed. [Answer] You might to ask yourself some questions: First of all, how many people would be on the planet if procreation continued as normal? Only about 120 billion people in total ever lived on earth. Of earths surface roughly 55 million km² are arable land (no deserts, no mountain ranges, etc.). 120 billion / 55 million ~ 2200 people / km². That is -mind you- with our earth's population growth rate. That is that of a averagely populated suburban area. Of these 120 million bodies, how many would be in "serviceable" condition? Considering that any body only 30 years before that event has become dust already. Since your setting is a medieval timeline, that makes about half of the 120 billion corpses already unavailable - resulting in 1100 people/km². Since population got drastically reduced during the event, how would population develop into modern times? Most of the population growth occured in recent times - and is exponentially. Since our starting point reduced the people capable of reproduction down to a few thousands, even with medical advancements, we can scrape off the gigantic amount added by recent generations. Additionally, with so many corpses available, people might do something... what would in reality be very frowned upon, further reducing the birth rate, or simply not see the reason for having more children. Also in war, reanimated corpses might be totally annihilated, partially prohibiting the resurrection of said corpses. Adding these effects Thus we could easily scrape off 90% of the remaining 60 billion people due to these effects and come down to 600 million living people and 5-6 billion reanimated corpses without further ado. Which is about the same population that we currently have in real life. So - unless you explicitly need an overpopulation problem in your world as a plot point - you might not even run into an overpopulation problem in the current generation. It would however occur in future generations. [Answer] There are a few other avenues to consider: ## Being undead isn't fun, and you may be next so you treat your undead with respect Eventually everyone dies. Being reanimated isn't life - you may be able to control your body insomuch as your necromancer allows you to, but your blood isn't pumping, you can't eat, and most of the pleasures and joy of mortality is removed for most people. Depending on the damage you might not have the same mental capacity (brain damage starts occurring within minutes of death), nor strength (muscle damage, rigor mortis), ability to move, and the possibility (likelihood?) that your sense will be dulled, and possibly not available at all. Even the best case, where your death didn't impact these things and your body was reanimated immediately, the undead will still miss out on the pleasures of food (no moving blood + no working organs = no working digestive system), sleep, etc. It will drive an undead batty, the necromancer will have to exert more control, greater restrictions, and eventually the "soul", inasmuch as there was one, will no longer be present. This leads respectful necromancers to wonder - what will happen to me when I'm dead? What do I want to have happen to me? Even in the absence of religion, it's very likely that people will have strong feelings regarding how long one should keep an undead around, and no doubt it will be a thought strongly on the minds of those who are undead, wondering how long they are going to be forced to live this way, and how long until they no longer have any real control over their death. ## Religious proscriptions Likely the problem of overpopulation will have cropped up early on, and for a variety of reasons the strong religious institution that teaches necromancy to all also teaches moderation and control. Perhaps the elders of the church will require that they be consulted for each raising - of course for purposes of time they either 1) allow quick raising, but then license must be obtained, or 2) everyone is given license, but if someone operates outside the rules their license is revoked. Those rules can be quite arbitrary, but it helps if there's a historical reason for each one. ## Necormancers lose control when they die Another option is that the magic keeping undead alive dies with the necromancer that raised the undead. This can be further strengthened if you disallow multiple necromancy - the first to raise is the controller, and that undead cannot be raised again if they are released or if their necromancer dies. This means the undead will live no further than one generation beyond their own, and thus the possible world population will never increase past 2 times the natural population (ie, people will live a possible lifespan of no more than 2x their normal lifespan). Could have some interesting implications - for instance the wealthy will always hire very young but competent necromancers to stay with them 24/7 so they can 1) be raised immediately after death, losing the least amount of physical/mental capability and 2) live the longest. The necromancer is then set for life, and in turn they may become very wealthy, hire their own necromancer, and so on. You may have very interesting caste/class systems due to this mechanic. [Answer] Make the undead unable to give new life. Basically raised people can have sex, but they can't have children. Now you might think that this still makes for a bigger population and you are correct. But it is not that huge of a difference. Math is on your side. To make calculations easier, we'll assume that child mortality is not an issue, people form lifelong couples and the ratio of men:women is exactly 1:1. We'll compare a world where necromancy doesn't exist, with the one where it does with the above conditions. let x0 be the number of people immediately after the apocalypse let c > 2 be the average number of children per pair let n be the number of generations we will look into the future Then the number of people without necromancy is: ![y formula](https://chart.googleapis.com/chart?cht=tx&chl=y%20%3D%20%5Cleft(%5Cfrac%7Bc%7D%7B2%7D%20%5Cright)%5E%7Bn%7Dx_%7B0%7D) And the number of people with necromancy is: ![z formula](https://chart.googleapis.com/chart?cht=tx&chl=z%20%3D%20%5Csum_%7Bi%3D0%7D%5E%7Bn%7D%20%5Cleft(%5Cfrac%7Bc%7D%7B2%7D%20%5Cright)%5E%7Bi%7Dx_%7B0%7D) Which is a simple geometric progression sum, hence: ![z formula summed](https://chart.googleapis.com/chart?cht=tx&chl=z%20%3D%20%5Cfrac%7B%5Cleft%20(%202%5E%7Bn%2B1%7D%20-%20c%5E%7Bn%2B1%7D%5Cright%20)x_%7B0%7D%7D%7B%5Cleft%20(2-c%5Cright%20)2%5En%7D) Now lets examine how fast z grows compared to y: ![z over y formula](https://chart.googleapis.com/chart?cht=tx&chl=(z%2Fy)%3D%5Cfrac%7B%5Cfrac%7B%5Cleft%20(%202%5E%7Bn%2B1%7D%20-%20c%5E%7Bn%2B1%7D%5Cright%20)x_%7B0%7D%7D%7B%5Cleft%20(2-c%5Cright%20)2%5En%7D%7D%7B%5Cleft(%5Cfrac%7Bc%7D%7B2%7D%20%5Cright)%5E%7Bn%7Dx_%7B0%7D%7D%3D%5Cfrac%7Bc%7D%7Bc-2%7D%20-%20%5Cfrac%7B2%5E%7Bn%2B1%7D%7D%7Bc%5E%7Bn%2B1%7D-2%7D) ![z over y to infinity](https://chart.googleapis.com/chart?cht=tx&chl=lim_%7Bn%20%5Cto%20%5Cinfty%7D(z%2Fy)%3D%5Cfrac%7Bc%7D%7Bc-2%7D) This means that with 3 children per family you will get up to 3 times more people with necromancy than without. With 4 children - up to 2. With 5 children - up to 1.67. And so on. [Here](https://repl.it/JF6b/0) is some code if you want to play around with different values. Now, 3 times more people might sound like a lot, but it's really not. --- ## tl;dr in case you don't care to follow the math: If 3000 people start reproducing and don't use necromancy, no matter how many generations you look ahead, there will always be more people than if 1000 people start reproducing and raise every single person that dies, given there are 3 children per family on average. If there are more than 3 - the numbers are even more in favour of the no-necromancy folks. Evident by [this graph](https://www.wolframalpha.com/input/?i=(+(3%2F2)%5E(n+%2B+1)++2000+-+2000+)%2F(+(3%2F2)%5En++3000+),+n+from+0+to+20). --- However, this required us to ignore infant mortality. One way to deal with it is to make raising babies/small children illegal and/or frowned upon. This doesn't look that far fetched given: > > 4. The undead body is preserved by magic. > > > My interpretation is that raised people don't get older and don't grow. Hence no one will want a couple to look after a crying infant for the rest of their lives and they will be nudged to try to conceive again instead. But even if you raise infants, the conclusion will still hold. It just won't be 3000 vs 1000, but 10 000 vs 1000 for example. [Answer] That's an interesting setting. Specially this bit: "Soul is bound indefinitely to the necromancer's will, but preserve their identity." Which I understand that the undead keep their personality after reanimation and are able to communicate. And have meaningful conversations and requests. Like "It's time for me to go, my dear". Which is a hard request to deny coming from a family member, knowing that you will very likely be reanimated as well and would like to have the same wish respected if/when you request it. I think that the amount of undead will regulate by itself and undead overpopulation won't be more of a concern than living overpopulation. It would be treated as a way to increase longevity for the most part. You'll have most of the population reanimated for a while and then liberated (aka unbinded and cremated). Some won't. Some will like to hang around for centuries, chaining reanimations (I see some aristocrat families taking pride of having 200+ years old members). You see I'm not worried about forced reanimation. It's because I think it would be quickly seen as something very dickish to do and revolutions would be fought to make it highly illegal. [Answer] Well, first let's consider how we interpret magic. From various descriptions I have read it could be suggested that there are roughly two perspectives on the nature of magic ( not to construct an arbitrary dichotomy here, but merely for the purpose of illustration ). One such view is that of enforced balance, i.e. magic is constrained by, let us say, "meta" laws of physics. This can also be seen as a creationist perspective or spiritual basis for the existence of magic, i.e. it just is because God said so. On the other hand, magic can be seen as a reinterpretation of the natural laws of physics. From this point of view balance is an abstract concept which applies in some hypothetically infinite universe, and therefore, locally, magical power is only constrained by one's knowledge of the natural laws. So in other words magical power ( and not magic itself ) is constrained by ignorance. This can be seen as the agnostic perspective, magic exists because the universe exists, we don't know why but clearly the magical and the physical are made of the same "stuff", each effects the other and both follow the same rules ( assuming we understand those rules ). One could argue of course that both perspectives have truth to them. EDIT: it was not clear whether the force described is adverse to the process of transporting souls based on the previous description, the below is reworded for clarity. Now iff, from the first perspective, your magic imposes a cosmic balance on the prospect of extracting souls from one "place" and depositing them in another, then one could describe a normalizing force or gradient which acts to prevent souls from being displaced from one plane of existence and deposited in another. The imbalance could be described as sort of capacitance between the planes of existence which would suggest ( given the normalizing constraint ) that the planes of existence are finite, or that the physics which separates the planes has limits - the latter being more palatable from a physical perspective as the former would not make much sense cosmically since we tend to think of the universe as infinite. However, iff, from the second perspective, your magic has no cosmic force which limits the movement of souls in such a way, i.e. the "capacitance" of the magical imbalance is infinite from a local perspective, then the only thing which limits the movement of souls from place to place is human sentiment, a simple cost-benefit analysis that humans compute intuitively and act on collectively as a society like ants with emergent behaviors. Given these two perspectives and your needs for the story, you could certainly combine aspects of both kinds of constraints to make the rules as complex or as simple as you like. [Answer] Limit total soul count Let's say something along the lines of... when people die, their souls are just swimming around in some kind of huge, eternal pool, where they wait to be reborn as someone else. This will completely limit the possible amount of humans in the world at one time. Now if the souls get bound to their former bodies through necromancy, it will decrease the number of souls that are ready to be reborn. So less and less people will get pregnant (though I guess the number of actual people is pretty low anyway). This will prevent overpopulation from ever happening and at this point in time, nobody would frown upon necromancy since the "soul pool" is still big enough to expand humanity a lot. Although I guess there's still the question if people even know about this whole system or are just blindly using necromancy 'cause it's so darn convenient (as people do). No need to explain that it will never happen Now this is a different approach which I thought I'd at least mention... since when do humans care? Sure, some do, but humankind as a collective generally doesn't. It's kind of like you're trying to write a story about our world and then say... nah stop, we still have to explain away overpopulation, global warming, etc. because otherwise people wouldn't keep living the way they do. [Answer] ### The undead body is preserved by magic. And that's the key. Treat magic as an almost-infinite resource easy to obtain but hard to replenish. Is a common setup in magic universes that "magic" is a consequence of the existence of living beigns. In other words, just imagine that "mana" is available in the whole world, but is more common or concentrated around places where life is more common as well, forests, big cities, etc... On the other hand, living corpses uses magic for living; it could be a delicate ballance between living beigns spreading magic as they live and undead beighs consuming magic as long as they're living. Create too many undead bodies and they wil deplete the magic of the zone quickly, and after that they will die (again) like my cell phone when it run out of battery. Or create just the right amount of undead bodies and they will consume the ambient magic at the same pace as it is replenished. If the ratio of magic creation vs magic consumption is 1:1 (one living being spreads enough magic to sustain one unliving being) you tie the amount of undead bodies to the amount of living bodies so, if in some point of time the undead outnumber the living ones, they wouldn't last for long. Life and death are tightly related. It's obvious that one cannot exist without the other. --- ### Nature don't like undeads, but tolerate them. It is not natural for a dead being to be alive, every cell in the body of the undead is craving for resting forever. Well, you can cheat nature using magic but, the longer you cheat mother nature, the more it costs. If the magic cost per day follows the graphic below: ![](https://i.stack.imgur.com/fEt2d.png) For each day of existence (x axis), the magic cost increases (y axis), so after 100 days of unliving, dayly cost is almost twice as the first day and 200 days after the cost is multiplied by 8. No matter how powerful the Necromancer would be, there would be a moment where the magic costs exceeds Necromancers power and this body cannot be kept living anymore. --- Maybe you can use both ideas at the same time! :) [Answer] You should think about how many dead are really there to be reanimated? Scenario 1: slowly growing living population (1% living population growth / generation): It takes about 70 generations for the living population to double, so looking back less than 10 generations, the living population seems constant. If animated dead go back fully dead after the controlling necromancer dies, the corpses would be unusable damaged after a few generations have passed. So at the very worst case, the full population would be about 10 times the living population. Note, that it is a constant multiplier! This means, the overpopulation problem would not be caused by the undead, but by the living, since the whole population is N times the living population. This means, if an overpopulation ever happens with the undead, it would happen a few year later even without the undead. Also note that raising bones would not take up much place, you could have probably 100 generation worth of dead relatives in the cellar. Scenario 2: rapidly growing population (100% living growth / generation, each family has 4 children on average): To simplify, let's suppose, only the "children" are living, parents, grandparents, etc are all dead. This means, if the number of living is N right now, the prev. generation had N/2 people, N/4 before that... So right now there are about as many people living as there are all the dead! (of course that nasty war throws off this calculation, making the dead population relatively bigger for a short time, but as generations pass, this will cause less and less error in the calculation). So basically, if your population is growing very fast, the number of people living now won't be much less than the number of people that are dead. So raising every single dead would probably double the population. Once more, the overpopulation is not caused by raising the dead, but the exploding number of living. Actually, on the contrary, in a fast-growing population the dead would be a scarcity, a resource hardly acquired, and fought over... [Answer] # Necromancy Mastery (Limit) The most easy way could be that your necromancers has a limit of undead that they can control. For example a boy could control 1 or 2 animals, a teenager 3 or 4 animals, a young man 1 or 2 person, a normal user of necromancy 3, and a necromancer teacher 5 or 7. By this way you can have a limit and also you can train it, like levels in a game # Life "Glue" In order to bind the soul to the death-body you need a way to stablish that link, you use your own life force to do that. A "casual" user won't note a difference, but maybe a normal user has 1 or 2 years less of lifespan and a proffessional 5 less years. By this way people has to chooce between comodity (undear servant and workers) and lifespan (more years). # Undead Aging Maybe you could do that death-bodies are always rotting, slowly, but rotting, maybe it could take 10, 30 or 100 years, but they can't be in our world. # Magical Undead Inmunity The dark magic that use your necromancers "stop" the aging and rotting of your undeads, but in the moment that the necromancer die, all the aging and rotting of the corpses is released instantly, so the undeads would be destroyed and nobody would be able to ressurect them. # Corpse Time Limit You can only ressurect people after some days of die, if you have a undead who was revived 5 years ago then when you die any necromancer would be able to revive them, because the corpse is "too old". # Undead Revenge Undead souls are difficult to manipulate, if they are to much years in our world they are more stronger and when the necromancer isn't able to controll the they can become agressive, if you have an agressive undead police could command you to destroy it for the your own good and the good of your neighbours. # One-use-souls Simple, undead souls can be only "tamed" one time. If the necromancer die they can be "tamed" by other necromancer (maybe powerful necromancers could transfer the control to other one). # Life Balance This isn't my idea, I only want to express my agree with the [DonFusili answer](https://worldbuilding.stackexchange.com/a/84708/35041). Recently, one week or two ago I saw something similar in a series. # Self Vanishing You said that undeads preserve their identity, so they after some years (20, 50, 100 or a little more) they don't want to "live" anymore, they are bored of living so much or the think that it's bad, so they will request to the necromancer to free they souls (if a dear person is asking you to release I think that you won't put much resistance, it's they own choice, not your). Also undead persons aren't able to enjoy mortals feelings, they only work without stop, they would't they release earlier or later. # Law Vanishing Think about yourself, after die, What do you want to your body and soul? Do you want to be an slave for the eternity? Maybe alive persons would make some "moral" laws about the years that an undead could be in our world. They will have rights! Maybe religion determine that laws. Also you could need a licence to use undeads, the licence has it own limit of undeads and time for each one, also if you do something bad you could lose your licence. [Answer] Here’s a novel answer: make the number of souls in an area limited to the number of people who used to live there. Whatever the historical greatest population was of a town, that's the total number it can be brought back up to via necromancy. This has the twist of limiting reanimated persons geographically and can cause complications when travelling. [Answer] A consequence of overpopulation might be food shortages, unemployment or perhaps plagues, right? But the undead may not have to eat, work or be capable of carrying disease (though I like concept of a civilization threatened by reanimated cadavers wandering around). Remember, overpopulation may be a perfectly fine thing to have in this world, so long as the problems or opportunities it would present are written away from the challenges of your protagonists. [Answer] Instead of trying to find a cool fun solution, you could just use economics. How do you prevent the world from being overpopulated with the walking dead? Some asshole figures out how to make money off of the space needed to care for a dead person, and then keeping dead people around gets too expensive. You can also solve the issue of people not using this asshole's service with social pressure ie "You keep your dead cat with your living cat!?, what are you poor/dumb/evil". This is a petty answer, but not ever problem needs to be solved with magic, even if it was made by magic. [Answer] Maybe instead of putting limits on undead, make some difficulties for the living - excessive use of necromancy makes one impotent. That way people can either command army of undead or have living family. It can fit nicely in Your idea of "necromancy as a religion", where most powerful necromancers can not have a family. ]
[Question] [ Is it possible to have plants that wouldn’t burn? Having the plant getting damaged by fire is fine, but I want the plant not to burn at all. It does not need to survive, it just must not catch fire (for roughly an hour). This is going to be a plant from another world, but I would like to know if this is possible with what we know of plant life on Earth. And if it is possible a little explanation as to how a plant could be fireproof would be greatly appreciated. The temperature should be at least 1200 °C, but ideally I would like to have 2000 °C. [Answer] To put something on fire, you need air (or another oxidizer), fuel (carbon inside the wood and leaves), and heat. Here are a few ideas how to delete one of them. Reduce heat A wood containing a lot of water does not burn well, as water reduces the heat while it evaporate. But even the most wet wood can burn if you set it one fire long enough, when all the water is gone. Oxidizer The plants could emit a gas that does not burn, replacing the oxygen around them by some fireproof gas (at lear near the ground, as they probably need oxygen to breathe somewhere). Dinitrogen maybe ? I don't know what kind of gas would be the most likely. It should be heavy enough to stay near from the ground (I like the idea of a toxic gas-producing plant that does not burn). Flames could not reach the plant. In a forest fire, the heat around could damage the plant but the wood itself could not be set on fire. Fuel Plants as we know them are carbon-based. You could imagine a plant made from something that doesn't burn but i'm not sure it will still be a plant, so let's keep carbon. The wood from your plants could be wrapped in something that does not burn. It could be something the plant itself produce, a kind of sap sweating from the wood, like the caoutchouc from the hevea tree (not the best example : the hevea does burn without problem, I checked on the net, there are many fires in hevea pantations, but your plant is an alien). Or it could be something the plant does not produce, like an alien form of spider web. The plant could bring spiders or insects some food and the insects could build a kind of fireproof nest around the trunk. [Answer] [Redwoods](https://en.wikipedia.org/wiki/Sequoioideae) are fairly fireproof while alive. The biggest issue to keep from burning is heat displacement. So The red woods have a LOT of water stored in their bark as well as having a think bark of 'dead' cells. it can dissipate the heat by letting the water absorb much of it and evaporate away, leaving the trunk much cooler. Being very large also helps dissipate the heat over a much larger volume. It takes a lot longer to heat a gallon of water than a pint. I believe [Aspen](https://www.safnet.org/fp/documents/aspen_mgt_08.pdf) are also a natural fire break because they also resist fire, I think once again it is primarily due to volume of water vs. material to burn. [Answer] > > Is it possible to have plants that wouldn't burn? > > > No. In order for something to be alive, it needs to have a source of energy that it can use to power its internal functions, such as growth. This energy needs to be stored. A living thing releases this energy in what can be thought of as a very slow, very controlled burn. It is this energy storage that means it is impossible for any living thing to be fireproof — heat up the energy storage enough and it will start releasing its energy. In the absence of oxygen the temperature at which it will burn is higher and not as much energy will be released when it burns, but it will still burn. So how do you make a plant fire resistant? The plant needs a way to shield its energy stores from excess heat. The other answers have mentioned ways that a plant can protect itself to a certain degree. Would a plant be able to protect itself from temperatures of 1200 degrees Celsius? No. 1200 C is the higher end for [lava when it emerges](https://en.wikipedia.org/wiki/Lava). Here's [a video of what happens when something organic is thrown onto lava](https://www.youtube.com/watch?v=kq7DDk8eLs8) — it explodes. 1200 degrees is past the point at which energy stores would spontaneous combust, oxygen or no. The best way to survive that high of a temperature is to avoid it altogether. Animals can simply walk away (lava usually isn't that fast), but plants don't have that luxury. The quickest escape route for them is down. Basically, you have a plant with a large energy store (something like a bulb) deep underground. The part of the plant above ground will burn and die, but the plant will be able to regrow from its underground bulb after the lava has cooled. [Answer] Unless these plants have some kind of magnetic shielding around them, they can't exist. 2000C is a full 600C above the firing temperatures of [typical ceramics](http://www.lakesidepottery.com/HTML%20Text/Tips/Tempruturerange.htm). (Cone 13 (1400C)is the highest temperatures found in conventional kilns. [High-fired Superduty kiln brick](http://ceramicartsdaily.org/wp-content/uploads/2010/06/firebrick-types.pdf) only goes up 1600 or 1700C.) [![Kiln Peep Hole](https://i.stack.imgur.com/vAMyM.jpg)](https://i.stack.imgur.com/vAMyM.jpg) According to the [Engineer's Toolbox](http://www.engineeringtoolbox.com/melting-temperature-metals-d_860.html), only a handful of metals have melting points above 2000C. They are: * Tungsten 3400 * Rhenium 3186 * Osmium 3025 * Tantalum 2980 * Molybdenum 2620 * Ruthenium 2482 * Niobium (Columbium) 2470 * Iridium 2450 None of these materials are conducive to life using any kind of chemistry we know of. Organic materials are burned off for sure by 300C. So if not metals or ceramics, what would work? A magnetically shielded plant might be able to survive those temperatures. (If magnetic bottles are good enough to shape the plasma of torchships, then it out to do just fine against 2000C.) Since [fire is a plamsa](http://www.askamathematician.com/2013/05/q-is-fire-a-plasma-what-is-plasma/) and reacts to electrical/magnetic fields, the plant could form a magnetic shield around itself to prevent burning up in such hellish temperatures. [![Flame in an electric field](https://i.stack.imgur.com/5Q943.jpg)](https://i.stack.imgur.com/5Q943.jpg) The problem will be in powering such a magnetic field and ensuring sufficient field strength over a sufficient duration to survive the required temperatures. A battery or capacitor would only last for so long. A related idea is the [Tesla Tree](http://hyperioncantos.wikia.com/wiki/Tesla_tree) of Hyperion though there's no description of how these trees are constructed. [![Tesla Tree](https://i.stack.imgur.com/Xg6Bi.jpg)](https://i.stack.imgur.com/Xg6Bi.jpg) [Answer] I was originally making this a comment but the idea evolved a little bit. So far everyone's suggestions have been for ways that the plant could suvive the fire, but you specifically state that it doesn't have to survive, just just can't burn. I'd like to put forth a suggestion that can meet the specific "die but not burn" criteria. As some have mentioned there are a handful of naturally occurring materials which do not burn easily. Technically anything can burn given enough heat/oxygen, but since you've got a temperature threshold set we'll work with that. Quartz for example more-or-less fits within that threshold, as [its melting point is over 1600 C](https://www.google.com/search?q=melting%20point%20of%20quartz&ie=utf-8&oe=utf-8). Imagine a plant that uses [seeded minerals](http://www.wikiwand.com/en/Seed_crystal) in the dirt or deposited through rainfall to grow a casing of crystal. The crystal could server many purposes, like protection from certain elements in the atmosphere, protection from predators, aid in the plant's particular brand of photosynthesis, etc. Chances are this plant would need some internal reinforcement to grow all this crystal and not fall over. It could have a wood-like exterior or even something resembling a skeleton. Or it could just have a thicker trunk section that tapers as it grows up, and short, stubby branches that don't need to support too much weight. Now when a brush fire hits the area, the crystal would survive but the plant inside might be cooked by the temperature. If there are only small gaps in the crystal (remember it would probably need some gaps in order to breathe) you would end up with something that would screen the plant from actually igniting, sort of the reverse of the principles behind the [Davy lamp](http://www.wikiwand.com/en/Davy_lamp) which is something cool I just learned about the other day. If there's not a big enough gap in the crystal, not enough oxygen could pass through at one time in order to let the plant actually catch fire, but it would probably still be killed by the intense heat. What you'd end up with after a fire is a field/forest of crystalline plant-shaped ghosts. [Answer] The extreme temperatures you want to invoke in your world would be a serious problem for living creatures made out of any feasible substance. There are some compounds that do not melt at 2000 degrees Celsius, but they are not going to be suitable to construct a living thing by themselves. What an alien plant needs to survive this onslaught is a way to keep the high temperatures away from its most vital parts. I would suggest a plant evolved to cope with this extreme temperature would burn, but in a controlled and limited way. Around the thicker parts of its structure (main branches and roots), it would have a thick skin constructed so that when it was exposed to high enough temperatures, it created a thick insulating blister of carbonised foam (pure carbon has a very high melting/ablating point of ~3600C, although it would oxidise if the air contained oxygen). It would expand like some over-cooked carbonised popcorn, encapsulating the vital core of the plant in what would probably need to be a very thick insulating layer. The plant would need to lose leaves, rootlets and other smaller structures that were not large enough to provide a thick enough insulating layer. They would just burn away. What would be left, hopefully, is a core of the plant that remained inside at a much lower temperature. Once the heat had gone, it would need to re-grow the lost parts from energy reserves kept aside for the occasion. [Answer] If you want the plant to not burn at all, you must somehow suppress the fire from ever beginning due to the heat. This can be done by a variety of techniques, but they all boil down to the fire pyramid: [![enter image description here](https://i.stack.imgur.com/rDx0m.png)](https://i.stack.imgur.com/rDx0m.png) In order to prevent fires, you must remove one of the edges from the fire pyramid. If you want the plant to not burn at all instead of merely surviving the fire, you must remove the Oxygen component, since the ambient temperature is already high, and the fuel already exists in the plant. This can be done if the plants can produce large amounts of chlorofluorocarbons or other chemicals that displace oxygen and other oxidising gases, preventing the fire from starting due to the lack of oxidiser. This makes the plant similar to a natural [Halon fire extinguisher](https://en.wikipedia.org/wiki/Bromotrifluoromethane). Meanwhile, the requisite photosynthesis gas exchange can be performed using structures that extend above the protection of the fire extinguishing compounds. They are therefore vulnerable to fire, and have to be replaced after each fire cycle. [Answer] The mature ponderosa pine (pinus ponderosa) is able to survive so-called "normal" fires. It does that by growing thick bark and by dropping lower branches while maturing. However less frequent more intense fires will jump into the crown and kill the tree. Similarly fire resistant thick-barked trees are longleaf pine, slash pine, loblolly pine and giant sequoia. Oddly the Australian eucalyptus manages better fire resistance than bark thickness would indicate. Possibly lower bark moisture content accounts for this. References: <https://en.wikipedia.org/wiki/Fire_ecology#Plants> <http://riel.cdu.edu.au/publications/register/riel1810> <http://www.agf.gov.bc.ca/range/publications/documents/fire4.htm> <http://www.nps.gov/fire/wildland-fire/learning-center/educator-resources/lesson-plans/fire-adaptation.cfm> [Answer] You've assumed the world is earthlike with similar pressures and air ratios. Can you redefine the world so that combustion is impossible - remove most/all the oxygen? Drop the pressure so that fire simply lacks the ability to start? I can't imagine a sea plant catching fire while under water. Size may be another saving grace - if your plant is so big that an entire continent would need to be on fire before "the whole plant" is burning ? Consider strawberry runners where each node is a separate plant but they grow outwards. Fire needs an oxidiser, a fuel, and a spark. The plant's form is the fuel, can your plant focus on removing one of the others? If the plant was large enough and stored a lot of water - could it function as an organic water main pipe and effectively extinguish fires by drawing water over long distances? Finally, can your plant reject flame somehow - I believe wind would be bad if it contains oxygen, can the plant store argon or nitrogen or something else inert and non-flammable? This could be like a MIG welder releasing gas to keep the fire away. [Answer] Your prerequisites are too hard for wood. At those temperatures over that time, any wood composed of organic materials will undergo pyrolysis and burn. But since it is not necessary for the tree to survive, maybe what remains need not be wood? Trees transport much of their water near the surface of the trunk with deeper layers largely "gunked up" and unable to be much other than structural support. Of course, structural support is vital so this is generally fine for most trees. But we could assume (with usual note about ass-u-me fully applying), a tree that instead has symbiotic microbes capable of dissolving and consuming such "inert" wood. The released nutrients and space could then be used by the tree. Such tree would grow width very slowly since instead always growing new layers outside the previous ones, it would push new growth inwards where now dissolved and consumed wood was. Now to the relevant part... We could further ass-u-me that some inorganic compounds would be insoluble, highly stable, and biologically useless to the tree. Such compounds would deposit as minerals in the core of the tree. Since deposition would happen at areas of low flow and flows are vertical, the deposition would be a continuous vertical structure. This would be favoured by evolution since it would provide the tree with longitudinal support. The real issue is that while such minerals would, being chemically inert, perfectly realistically not burn, the high temperatures in the question will melt most minerals. Such melting would then cause the core to become a puddle with some sand in it, which is not adequate. So let's ass-u-me another hypothetical system that conveniently transports minerals with lower melting points outside to provide the tree with bark that doesn't burn in normal fire and will give even beavers indigestion. Such tree would leave behind a core of hard stone in the shape and to some extent structure of the tree that created it. Suitable minerals for the core might be quartz and corundum. Both silicon and aluminium are common in the soil and generally useless to organisms. The rock core would have lots of impurities from other minerals so I guess it would end up being kind of indistinct in color and appearance. While the minerals are hard I doubt such biologically deposited highly impure mess would be. Which might reduce brittleness. Both quartz and corundum have melting points in the right range, so as long as the core is not too impure it might survive the heat for few hours with superficial damage. It certainly would not burn. It might even become harder. I doubt anyone would confuse it with wood, though, despite the shape and structure. [Answer] To add another answer than "water doesn't burn", you could check out: ## Make yourself as small as possible If you have a lot of surface area, you have a lot of area to heat up through. If you make yourself small, the area the fire can touch will decrease, thus it'll be able to survive longer before burning up. Just imagine yourself curling up, you hide almost 50% of the surface! In case of the plant, only the outer layer will take the big punches, leaving the core of the plant (somewhat) intact. There are [plants which curl up when touched](https://www.youtube.com/watch?v=JR_fdPm7mOI), or like the [venus fly trap](https://www.youtube.com/watch?v=EzyoD19q1YQ) close up when there's a fly, so plants are capable of some movement. Just image a version where ir compacts/twirls up all together, as close to the ground as possible. Less surface area means less effect by the fire. ## Shield yourself There is a [material called Aerogel](https://en.wikipedia.org/wiki/Aerogel), which is about 99% air. There is a lot of air trapped inside the material. Because of that, the stuff is an excelent insulator! You can barely feel the heat on the other side of the material. There are more of these materials available. There's a tv show (can't come of with the name) which makes a person touch one side of a sheet, and then a guy with a flamethrower goes mad on the other side. The result: His hand got a little warm. The plants could have some sort of (chemical) reaction and create a foamlike substance which acts like the Aerogel does. The plants aren't in lab conditions, but any shielding will add time until the plant gets damaged too much. It could be that the plant can create more and more for a while, keeping the shielding 'fresh'. ## Dig yourself in This doesn't require a lot of creativity, but it does do the job. In case of extreme heat, dig in. Twirl into the ground so that your a few centimeters below the dirt. It'll still be hot, but you have an insulator now, again buying it some time. ]
[Question] [ In what ways could an island be protected from tsunamis, given the following constraints?: * It lies in the middle of the ocean, at least several hundred kilometers from the nearest continent. * It does not rise up from a continental shelf - the surrounding ocean is at least a couple of kilometers deep. * It is at most ~25km wide in the longest dimension. * It has "line of sight" (along the surface of the planet) to a fault line, subduction zone, anything that might result in a tsunami. (See Easter Island for a real-life example that satisfies these rules.) Possible parameters to consider include the shape of the island, the slope of the insular shelf, the island's topography, etc. So far, I've been able to come up with the "obvious" solution of having the island have high cliffs all around the coast, but I'm curious what other solutions there are that I haven't considered. [Answer] You have the right idea, but misplaced. All that is required is that the island be the peak of a seamount which rises steeply from the ocean bottom. Tsunamis in open ocean have little amplitude (ships hardly notice them), but extremely long wavelengths. When these approach a shallow, sloping coast the water in the fromt of the wave starts to slow down, and the rear part catches up, the velocity of the wave increases and water starts piling up into a much higher, shorter wave. Coasts with a steep underwater approach simply don't get the "tidal wave" effect. Another way to look at it is that, since a shallow approach produces a short, high, fast wave, the wave has no chance to move laterally around an obstacle, and tries to go over it. A longer, slower wave has the time to be deflected around an obstacle without much amplitude increase. EDIT - In comment, the question was asked, "what do you mean by "the velocity of the wave increases", and a response will be too long for a comment, so I add it here. The short version is that I misspoke - the velocity does not increase. As the wave propagates into shallower water, it loses velocity (proportional to the square root of water depth), and gets higher. As its height increases, though, at some point the wave shape changes from being part of a wave system to that of a solitary wave - basically, once the wave trough touches the sea bed the behavior of the wave changes radically. I misspoke in saying that the wave speeds up. It does not. What I meant was that the higher the wave, the faster it propagates once it becomes a solitary wave. It may help to consider that a wave is in constant collapse, as the weight of the total wave causes the lower sections of the wave to squirt forward. The higher the wave the greater the pressure and the faster the base of the wave moves - and the dynamics of the wave as a whole keep the upper section in place, although the actual water molecules are constantly recycling their positions within the wave. And, of course, at this point the wave will begin dissipating as it travels inland. If you ever watch one of those documentaries about the crazies who surf the Condition Black (40 and 50 foot) waves in Hawaii, you'll notice that all those surfers get carried out on jet skis and start their runs behind the jet skis. That is, they don't get dropped off, stationary, at the base of the wave. There's a good reason for this. If they are stationary in the water, the wave moves so fast they they can't accelerate fast enough to keep up with the surfable portion of the wave face, and will either fall down the vertical portion or get left behind by the wave, depending on the exact shape of the wave. Mostly, they fall down the face and get driven under. [Answer] I live on an island where we have had a couple of tsunami. The parts of the island least affected (on the side it was hit) were the ones with steep dropoff into the sea. A gradual rise like a tropical beach is what makes tsunamis so dangerous. A boat in mid ocean might not even notice a tsunami. So natural defence is steep dropoff without sloping beaches. Don't rely on reefs, those get destroyed and they don't recover within a human lifetime. But tsunamis main danger is an uneducated populace living in the prime habitat of the lowlands and beaches. If your island has a history of tsunami caused by a fault line, it's only going to get hit hard from one side. The reef if any on that side would be long gone, the land itself would be shaped by successive tsunamis, and you may have a situation like some of the Marquesas where all the beaches are on one side and the other side is mostly sheerish cliffs with no reefs. So you only need cliffs on the affected side, fault lines don't move around arbitrarily, all the tsunamis will be coming from the same direction. [Answer] Mangrove forests. Video of a model in action: <https://www.youtube.com/watch?v=ljLAfU132sw> <https://www.newscientist.com/article/mg22430005-200-mangrove-forest-planted-as-tsunami-shield/> They break up the waves, the deeper the row of trees the better. It's quite simple really. It will make that part of the coast hard to use for fishing and genera; boat usage. [Answer] What about a barrier reef? [![enter image description here](https://i.stack.imgur.com/WyotD.jpg)](https://i.stack.imgur.com/WyotD.jpg) For example, the island in the center of this atoll (Bora Bora) is about 1/5 the size of Easter, and it is going to be much less susceptible to waves of any sort. I'm sure an island the size of Easter could have such a barrier reef as well. [Answer] Bio-barrier Stack a series of large rocks inland from the beach, and add plantings like mangroves, palmettos, and other beach plantings to fill in amongst the rocks. This does not prevent flooding, but it does calm the wave system when it comes rushing in. You can see these rocks in action about a little after a minute into [this film](https://www.youtube.com/watch?v=DZZFPCY6RlE). The surge of a major tsunami can get up to 30m height, [but the level raise is usually about only 3m](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjVh9_KzOnSAhUS3mMKHcZ5DpAQFggcMAE&url=http%3A%2F%2Fnews.nationalgeographic.com%2Fnews%2F2004%2F12%2F1228_041228_tsunami_2.html&usg=AFQjCNGnotwQ2xn-NrIKzDVoAfHiSbFvLA&sig2=nTTDht2wm0c8Whp7uH2z2g&bvm=bv.150120842,d.cGw). Your bio-barrier can prevent the majority of the damage caused by surge, and your protected buildings can be naturally on a rise 3m or more uphill from the beach, or on solid stilts. Education The death toll difference between the 2004 and 2011 tsunamis was likely to do with missing infrastructure in the former, but also due to citizens of Japan being more aware both culturally and formally by education: there was an earthquake, something's wrong, get to high ground. In your question, we can't provide artificial infrastructure, so I would say that in addition to your bio-wall, you can provide education. Geography If you know in general which direction your tsunami is approaching from, make sure you do not develop on the beaches of the opposite side of the island. On smaller islands, the wrap-around effect ([refraction](http://www.coastal.udel.edu/ngs/waves.html)) makes the back side of the island much more susceptible (but of course the front gets slammed, too). Prioritize residential units on higher ground - if you have to prioritize. If the tsunami occurs during the night, people will likely be sleeping, so they may have no clue that it's coming. So, if you have to have buildings near the water, use the types of buildings that will be occupied during the day (commercial units) where people are awake and can be better informed to get to high ground. [Answer] A breakwater at sea A 'barrier reef' grows out of the continental shelf and would be destroyed by successive waves. Let's go one step bigger: Half way between the faultline and the island there is a chain of underwater mountains (pretty much other islands that don't quite reach the surface) that rises from the seabed for several kilometes. This causes any incoming tidal waves to break over the range rather than the island itself. For story purposes the breaks should be visible from the inhabited island -- though the islanders might not know exactly what they are seeing. The energy from the broken wave then has time to be reabsorbed into the deep water before it gets to the island. Problem: I don't quite understand where the energy from the tsunami 'goes' after it breaks over the mountain range. Why would it hit the island with any less energy than it left the range? Would it really be reabsorbed into deeper water? Another problem: Tidal waves have MASSIVE wavelengths when traveling over deep water.. They can stretch into the hundreds of kilometres. Boats might not notice them. 'line of sight' is about 5km at ground level. I can't imagine 5km is enough distance for a tsunami to properly form in the first place. A Solution: Okay the faultline is not visible from groundlevel, but it might be visible from the island's highest mountain. Still at 500m the horizon is still less than 80km away. . . Another Solution: Since they cannot form properly in the space provided, these are 'not normal tsunamis'. They do not have to behave like normal tsunamis and 'realistic' countermeasures do not apply. [Answer] Lowering the possibilities of a Tsunami : would be pretty hard, if not outright impossible, but if you could destroy a part of the ocean around you, make the depth there lower and so on ( it is impossible ) Another impossible way is to : stop earthquakes, hence stopping tsunamis. Problems ? Countless... Earthquakes are created by the formation of new land, explosions in the mantle ( if I remember well ), the tectonic plates moving and crashing against each other, huge explosions on a scale of an atomic bomb... Hmmm what other ways have other people not mentioned... Oh yeah, if you have let's say limitless resources, a more available way would be to build a dam or something like that, as defensive wall against tsunamis ( also impossible, since tsunamis carry the force of an atomic bomb and I suppose we don't have much to go through after that. ) And lastly making an underground city, not affected by tsunamis, something like a secret base and sooo on... Problems ? Yes, the earthquakes would be a lot more severe in this case. Welp... that's it from me.. not anything useful, but nice ideas... I think. ]
[Question] [ There is a planet that is orbiting around not a single star, but the core of a galaxy. It is independent of the other solar systems in the galaxy, but is affected by the center of mass of the core. It is orbiting very near the speed of light. It does have a clean orbit, meaning, it does not collide with any other planets or stars in the galaxy while it’s orbiting around the core. It is very difficult to land a spacecraft on this planet as only a few civilizations in the galaxy can approach a significant fraction of the speed of light, therefore only the most advanced ones can come close to the planet and land on it. The question is: would it be worth it to colonize this planet for any reason? Politically, economically or from a military standpoint? Or use it as a treasury, or anything? Would we have any use for it? Would it be worth any investment? (The technology to live in very cold places, far from stars is already developed and established, so even if this planet does not have an atmosphere and very cold, cities could be build on it which can support life with existing technology) [Answer] My gut instinct is "no: don't colonize." The biggest problem I see with this planet isn't the cold: it's time dilation. Politically, most civilizations can't even send diplomats there - and with time dilation, I can't imagine it would be a "key player" in intergalactic politics. Economically relies a lot on how the economy in the rest of the galaxy works. With that said, even if there are a lot of key resources on the planet itself, exporting them would have to outweigh the costs of the ships required to get there in the first place. Furthermore, that time dilation rears its ugly head again: time is money! (Setting up an interest-earning account, going to this fast planet, then returning to collect your earnings may or may not be a viable solution, depending on banks.) Militarily is a little more interesting. It's moving fast enough that I don't think it would be a key defensive or offensive position. It'd be hard to invade due to its speed... but all someone has to do is move something massive into its orbit and wait to effectively eliminate it. (Launching a kinetic weapon from it might be useful, if you just so happen to be going by someplace interesting at just the right time.) The only positive feature I can see would be to someone wishing to "time travel to the future" - and even then, it only works if they'll end up close to where they want to be when they want to leave. Once all that is said and done, however, it might be of interest to scientists who wish to perform experiments - either observing very long-term experiments off-world, or perhaps some relativistic experiments on-world. [Answer] Well, not colonization, but certainly a research station. There is exactly one location in the galaxy which fits your description - close orbit around the super black hole (~4 million solar mass) which inhabits the center of the galaxy. For a Schwarzchild geometry, there exists an unstable orbit at twice the Schwarzchild radius, with an orbital velocity of 0.7 c. The closest stable orbit occurs at about 3 times the radius, but the orbital velocity is a good deal less. Of course, construction will be a problem, since tidal forces will run several thousand g's per meter of radial distance, so some sort of gravitic control on the part of the advanced races will be a must. And let's not forget the radiation problem. This close to the black hole, infalling radiation and matter will have achieved very respectable energies. [Answer] While the amount of time dilation isn't as extreme as something going at .9 c, it is still enough to make some significant difference between the planet and objects in the rest of the galaxy. Since time is money, this could be exploited for various economic effects. The simple example of a person collecting compound interest in the outside galaxy while residing on the planet shows some of what is possible, and eventually many more subtle and complex financial instruments could be devised based on the time differential between the planet and the remainder of the galaxy. The other effect which comes to mind is the use of the planet for long term storage. Items which have limited lifespans but command a high value could be stored on the planet and have their lifespans artificially extended due to the time dilation effect. Of course, don't expect this to allow you to store a bottle of wine for millennia, the time dilation effect is not all that great at .6 c [![Time Dilation factor](https://i.stack.imgur.com/g4NHY.png)](https://i.stack.imgur.com/g4NHY.png) Realistically, if there is a desire to use time dilation for political, economic, social or military ends, it would make more sense to either build some sort of construct near the event horizon of a black hole or travel at relativistic speeds in order to take advantage of the Lorentz factor. [Answer] You're going to need to give it handwavium shields. lets assume 0.9 c as it's speed. Lets assume that it's path is as clean as interstellar space without any gravel or asteroids. The only thing it hits is the fine mist of atoms between the stars. Lets treat the planet as about the size of earth. Volume: 1.08321×10^12 km3 mass: 5.972 × 10^24 kg Surface area: 510.1 trillion m² Approximate circumference: 40075 km approximate cross section: 1.28×10^8 km² using the figures for a cold neutral interstellar medium from wikipedia: 20—50 atoms/cm3 So let's go with 25 atoms/cm3 25000000 atoms per cubic meter. We can treat the volume of space that the planet passes through as a cylinder with a cross section of 1.28×10^8 km² Now lets look at how much it hits while traveling, say, 10 light years from an outside reference frame (I think about 4 years planet-time). I'm going to ignore time dilation because it's hard and I need to maintain my sanity. Treat it as a cylinder 10 light years long with the diameter of the planet. This lets us estimate the total number of (almost all hydrogen) atoms in the path of the planet, lets assume they all hit and there's no shockwave effects: 37984965888934182667500000000000/pi m^3 (cubic meters) so over the course of 10 light years it will impact with 505924000 metric tons of gas atoms. How much energy will they be carrying? 505924000 metric tons at .9c carry 5.885×10^28 J (joules) This energy will need to be radiated away by the surface. To do it accurately I would have to take into account time dilation but to err in favor of the planet and to keep myself sane I'm going to ignore it. Surface area is 510.1 trillion m² The planet needs to radiate away 6.7180365296 × 10^23 Joules per hour. Dividing by the surface area each square meter needs to radiate 365.8 kW per meter square For comparison the sun radiates ~17.53 kW per square meter of it's (approximate) surface The surface of this planet is going to be glowing hotter than the surface of the sun You don't need to survive the cold, you need to survive the heat. [Answer] As a few of the others have said, due to time dilation, this planet wouldn't be very useful as a colony. Between the speed and the proximity to the SMBH, it would probably be one of those situations where every hour that you spend on the planet, a hundred years go by in the rest of the galaxy\. But there is one thing that it could be used for, and that's long term storage, especially of data. Scientists have looked into all kinds of long term data storage methods, trying to find something that could last 1000 years or longer. But by using the time dilation you no longer have to worry about that at all. Send a library probe to the planet, and 20,000 years is only a few days on the planet. Updating and retrieving information would be slow, but possible. You simply fly your ship near by and use a laser to make your data request. The library receives the request, the super computers do the lookup and 3 ms later it uses its own communication laser to send the information back. Back on the ship it's been 3 months, and the reply comes back with the recipe for how to make yum yum sauce that had been lost in the last galactic collapse. \ This is only an example. [Answer] It occurs to me to wonder how large the radius of the orbit is, and what the centripetal force would have to be to remain in orbit, and what the mass of the primary would have to be to keep an object in orbit at such a speed. If the radius of the orbit is the same as Earth's distance from the sun and the orbital velocity is 0.8c, then using classical mechanics -- ignoring any relativistic effects --, v^2=GM/r, I calculate the mass of the primary at 1.3e38 kg, or like 100 million times the mass of our sun. The centripetal acceleration, v^2/r, would be 384,000 m/sec^2. Earth's centripetal acceleration is about 6.3 m/sec^2. The force to keep this planet in such an orbit would be huge. I seriously question if it wouldn't be torn apart. But for the sake of the story let's assume it's possible. What would be the advantages of colonizing such a planet? Assuming near-light-speed travel is not routine in this society, it might be difficult and expensive to reach. That could make it a good place to store something valuable, the secret plans to the Death Star or whatever. But if you have the technology to reach the planet, presumably you have the technology to launch a spaceship travelling at near-c, in which case you don't need the planet for your high-speed storage. That is, any benefit gained by the planet travelling at such high speed, to get there you have to have a spaceship that can travel that speed. Why not just do whatever on the spaceship, and why do you need the planet? Unless it's something on such a huge scale that you need a planet for it. Time dilation would mean that time on this planet would pass very slowly relative to the rest of the galaxy. Good if you want to see the future or leave some message for posterity. Maybe a place to keep an archive that will survive for thousands of years of outside time. (But again, why not just put it on a ship?) Not so good if you're worried about keeping up with technological advances. A military base on this planet would be obsolete very quickly. It would also be difficult to keep up with news from outside, as it's happening so fast relative to you. So as a military or political center, it would be a terrible choice. Might be nice for research on relativity. Besides that, I'm hard pressed to come up with any advantage. I suppose the planet might have some valuable resource that has nothing to do with its unusual orbital speed. But that begs the question. [Answer] Assuming that such a planet is stable, and assuming you're limited to relativistic travel in your universe, this planet might be extremely valuable as a way station. To get from one planet to another quickly you have to expend a huge amount of energy getting up to near lightspeed, then expend that same amount of energy again to slow down to synchronize with your destination's orbit. But this planet is already moving at near lightspeed. So with careful planning to meet up with the planet as it matches the direction of your travel, you could make a pit stop for refuelling, trading, etc. without incurring the energy cost of slowing down. [EDIT] ...except that I didn't consider that the gravitational attraction of the black hole is going to be accelerating the ship as it comes in. That could be enough to invalidate my whole answer. [Answer] That planet could be the galactic Panama Channel. If you want to go from one side of the galaxy to the other, and you either don't want nor can't use shortcus (wormholes), then you have two options: hop from arm to arm, or go through the core. The planet could then also harbor a transportation hub, where ships can ressuply, or where you could unboard one shuttle and board another one. It could be neutral ground for negotiations. If it's hard to get there due to the delta-V you need to get there (due to its orbital speed), then it should be very costly, probably prohibitively costly to send a large military fleet there. Only relatively "light" crafts may be able to get there, so even if space fighter craft can get there, the carriers, motherships, frigates, destroyers or whatever you'd like to call the bigger ones can't get close. It could thrive on tourism. Think of the Everest in our own world: people want to reach it its top just because it is hard and it is there, and this keeps an economy going at the base of the mountain. The top of the galactic everest is the very core of the galaxy, with your planet being the place where the galactic sherpas live. It could be a tax haven. If it's hard to get there, it is implied that it's hard for auditors to get there. It could be a pirate hideout, just like some islands in the caribbean during the 1700's. Okay, this is not proper colonization, but the pirate population could grow enough to become a society on their own. And since not everyone has the technology to get there, then some race or civilization who can get there may monopolize transportation to and from that planet, and make a hell lot of money. [Answer] Your advanced race could colonize it because of prestige ("the coolness factor" / "because it's there" / "because we can"). Prestige in the difficulty of not only getting onto the planet, but hardening the colony against the radiation, tidal forces, and all the other cons mentioned in other answers. Sort of a galactic "my tech capability is bigger than your tech capability" contest. Similar to the Cold War era "space race" here on earth. Not sure if that would be very advanced, or very immature, though... but hey, you might just have the need for such an antagonistic race in your story. [Answer] A better military option. Storage of troops. Assuming a great enough time dilation, you can land 1 million troops and 1 million support personnel every year. Spend a fraction to support them (only a short time has passed for them) and in a hundred years launch a 100 million person armada. You would need to refit with modern tech, or hope technology did not drastically change. [Answer] Your orbit doesn't correspond to any known theory of gravity. If it's travelling extremely fast, but isn't orbiting any particular object (like a supermassive blackhole), then it will very quickly exit the galactic core. Source: <https://en.wikipedia.org/wiki/Escape_velocity> [Answer] I'm pretty sure that matter going that fast is extremely unstable. This planet might be glowing hot just from its own movement. I also think it would be shaped like a bent spear just from pure force, being slung around in very small orbits very VERY fast. Landing would indeed be difficult, because contact with matter going this fast is going to give a hell of a recoil. Your ship needs to be able to take a punch, because this planet has an enormous mass (because it's a planet) and an even bigger force (due to going near the speed of light). If you can't keep up it would be the equivalent of an unstoppable force hitting a fly. Then there's part three, the difference in time. Time, gravity and speed are very closely related forces, as far as more sciencey people tell me. Even if the landing succeeds and the colonizing mission only takes one day on that planet, when the crew returns home they might discover that two centuries have passed at a safe distance from this black hole. Is this colonizing mission worth it? I dunno. But something on that superfast planet should be worth a lot if it requires this much effort, because it sort of stretches the "doing it because it can be done" mentality. [Answer] The reasons why to not to do it mention radiation, time dilatation, nonexistence of such planet etc. Even if such stable planet exists and our civilisation can deal with the radiation and forces in such system there is one point - you have to catch the planet to land on it. Using Newton's law $F=\frac{dp}{dt}=\dot p$ and relativistic definition $p=\frac{m\_0v}{\sqrt{1-\frac{v^2}{c^2}}}$ we can estimate the thrust of the spacecraft to accelerate to the desired speed. $$F=\dot p=\frac{m\_0+\sqrt{1-\frac{v^2}{c^2}}}{1-\frac{v^2}{c^2}}\cdot\dot v$$ It's easy to see that for constant acceleration $\dot v$ the thrust force $F$ diverges to $+\infty$ and for given thrust force the acceleration goes to $0$ when $v\rightarrow c$. For $v=0.9c$: $F=\dot v\left(5.26m\_0+2.3\right)$ for $v=0.99c$: $F=\dot v\left(50.25m\_0+7.08\right)$ [Answer] Assuming there are no in-universe technological reasons to not colonize it, I see the Time Dilation factor as highly useful from an archival standpoint. As humans with only one colonized planet, we have already seen the need to preserve history and things like seeds in vaults that are to be used in the case of disaster, why would a highly intelligent race not do the same things with their history, seeds, and other vital records? Throw those items onto a planet where time is passing more slowly, and you have a preserved, living record. This helps avoid the "Dark Age of Technology" problem in failing civilizations. [Answer] Militarily, I could see one use for such a planet. Assuming that your civilization is advanced enough to land on it, they are advanced enough to move a galactic body close enough to gravitationally nudge the planet out of orbit. With nothing to slow it down, the planet would be a near light speed rocket which would destroy most anything it hit. Such a civilization would likely be able to make the calculations necessary to direct it to where they want it to go. ]
[Question] [ My world is in the mid-Bronze Age, very loosely based on ancient Mesopotamia. Metal is scarce and generally of poor quality, and the only iron available is meteoric in origin. Gold is relatively common, and is used liberally for decorative purposes. The continent is split in two by an enormous crevasse of magical darkness, within which tiny, distant pinpricks of light can be seen. Nothing that enters it ever comes back, be it animal, vegetable or mineral - it simply falls until it fades from view. Following a series of military successes, the Emperor has decided to establish trade and communications with the Distant People dwelling on the other side of the crevasse. At the narrowest point of the fissure, the locally available materials are stone, clay, plant fibers, and a limited number of short trees. A river flows near enough to the city for it to be practical to ship materials there from further afield. How far apart should the sides of the ravine be for the bridge to require an 'ancient wonder' level of effort to build, while not being completely impossible? [Answer] Let's see what we can find from reality, both present and historical. For reference with the dates in this post, the Bronze age lasted from very roughly 5,000 years ago to 3,000 years ago, though both start and end very much depend what region we're talking about. The earliest bridges I can find: [![Tello bridge](https://i.stack.imgur.com/xNIvr.jpg)](https://i.stack.imgur.com/xNIvr.jpg) Tello bridge is 4,000 years old, largest span ''unknown'', I couldn't find any cite, but seems largish given the humans in the picture. (via <https://www.britishmuseum.org/blog/worlds-oldest-bridge-being-preserved-iraq>) I'm not 100% convinced it was even a bridge. [![Umshian root bridge](https://i.stack.imgur.com/ZGvVg.jpg)](https://i.stack.imgur.com/ZGvVg.jpg) Umshian root bridge is only maybe 130 years old, but suggests another possible method of creating a bridge if there are vines that have evolved to grow long and strong enough to go a long way down into the crevasse: just make the vines grow along ropes, and over time, grow it bigger. Admittedly, a rope bridge may be more practical! Not sure the span, but he seems to be 150ish pixels tall, but is leaning forwards, so may be foreshortened in this position; the bridge seems to be 1700pixels wide, so we can guess it's at least 12 m (40 ft) wide, and one source (<https://morelifechanger.in/firming-double-decker-root-bridge/>) claims it's "about 50 meters long" (~160 ft). (via <https://en.wikipedia.org/wiki/Umshiang_Double-Decker_Root_Bridge>) [![Tarr Steps](https://i.stack.imgur.com/qCXnc.jpg)](https://i.stack.imgur.com/qCXnc.jpg) The Tarr Steps are old (perhaps from the bronze age, others think medieval) but have very short spans, just a few feet each. It's also super unlikely that these are the original flags, given what feet and river floods will have done over the last few thousand years, so it's been rebuilt many times. (via <https://en.wikipedia.org/wiki/Tarr_Steps>) [![Arkadiko bridge](https://i.stack.imgur.com/C3sfP.jpg)](https://i.stack.imgur.com/C3sfP.jpg) Arkadiko bridge has a TINY span. Just look at it. 1m (3 ft). And again, I'm a little skeptical of how original the stones are, but it's estimated about 3,000 years old. (via <https://en.wikipedia.org/wiki/Arkadiko_Bridge>) [![The unfinished obelisk](https://i.stack.imgur.com/RChFt.jpg)](https://i.stack.imgur.com/RChFt.jpg) The unfinished obelisk is not a bridge, but bear with me. This was a stone pillar, started about 3,500 years ago. It was planned to be the largest obelisk in Egypt. They stopped carving it when it cracked. BUT. It was 42 m long, and tapered. If it had worked, that'd make a nice big span! If you have each side cooperating, and each one mines and pushes one of those out to the edge of the crevasse, you've got yourself a span that's about 40m of stone. More if you want to span the middle with a couple of trees. The danger is, of course, it's brittle, and likely to crack, and both sides are now near their tipping point and need counterweights. (via <https://en.wikipedia.org/wiki/Unfinished_obelisk>) [![Stonehenge](https://i.stack.imgur.com/L3a6F.jpg)](https://i.stack.imgur.com/L3a6F.jpg) For comparison, Stonehenge's lintel stones (4,000 to 5,000 years old) are only 3 m (10 ft) long, and the unsupported length is even shorter. (via <https://en.wikipedia.org/wiki/Stonehenge>) [![General Sherman](https://i.stack.imgur.com/pj2kD.jpg)](https://i.stack.imgur.com/pj2kD.jpg) Convenient tall trees, or joined wood, would be better than stone. More flexible, lighter, easier to harvest, easier to counterweight, less prone to catastrophic cracking. Some of these, rarely, can grow to a height of over 100 m, making a bridge length of perhaps 80m entirely possible with both sides joining the trees. By binding a third tree tightly to join the two spans, you wouldn't even need to cantilever, at least not after construction. (via <https://en.wikipedia.org/wiki/List_of_tallest_trees>) I still feel that the other answers are correct, though, and a rope bridge would be best, because at that point you're limited only by the strength and weight of the rope. [![Queshuachaca bridge](https://i.stack.imgur.com/Pchhn.jpg)](https://i.stack.imgur.com/Pchhn.jpg) Queshuachaca bridge is at most one year old: it is normally remade annually, but collapsed in 2021 because it was not maintained in 2020. It was first built by the Incans about 650 years ago. Nobody knows when their practice of rope-bridge building started, though, other than that it goes back to at least Incan times. It has a span of 36 m (118 ft), but examples up to 45 m (147 ft) were once known. (via <https://en.wikipedia.org/wiki/Queshuachaca>) [![Seaford Head cliffs](https://i.stack.imgur.com/zjXHv.jpg)](https://i.stack.imgur.com/zjXHv.jpg) Oh, here's one last idea: if the gorge is narrow enough, made of the right kind of rock, with the right faults, they could find a parallel faultline, and calve off a section to tip across and lean against the far side. Alternatively, they could try carving it out like the dolmen. Then once it's leaning against the other side, they can either carve steps in it, or just fill in the gap all the way up to ground level. [Answer] This is close to a duplicate of [Building a bridge from one side](https://worldbuilding.stackexchange.com/q/67360/40609). However, the limitation to the Bronze Age perhaps makes this a unique enough question. That question does make one point: somehow you need to cross the ravine before you can build the bridge. A tall tree, cut to guarantee both sides could handle someone's weight, could be one limit. But that would limit the bridge to maybe 30 meters. So, is there anything else we can do with Bronze Age tech? I'm thinking your limit is a Bow and Arrow For comparison, the Bronze Age was [3300 BC to 1200 BC](https://en.wikipedia.org/wiki/Bronze_Age). The catapult was invented in [400 BC](https://www.smith.edu/hsc/museum/ancient_inventions/hsc11b.htm), which means it's not a bronze-age tech. On the other hand, the bow and arrow has been in use since approximately [72,000-60,000 years ago](https://en.wikipedia.org/wiki/Bow_and_arrow), which establishes the bow and arrow as the only move-something-a-long-distance technology we have during the Bronze Age. The Longbow world record is held by Jeremy Spencer, [379.51m](http://www.tyndalearchers.co.uk/archery/flight-archery). For practical math purposes, let's say that our initial limit is 380 meters. But that was a perfect shot... The oldest longbow specimen can be traced back to [2690 BC](https://www.johnmooremuseum.org/medieval-archery-the-longbow/), so we're clear in that respect. But Mr. Spencer's world record shot was with, frankly, a perfect arrow shot either inside or on a perfect day... it's the proverbial long-shot even with the sacrifice of a couple of oxen. But it was also one more thing... unburdened. Your emperor's workers would need to drag something across that abyss to start the process of bridge building. Now, I could drag out all the math about forces, velocities, mass, friction, and drag. But what it's going to basically prove is that the next limit is 75-100 meters. *EDIT: User @MartinModrák points out that a structure could be built on the Emperor's side of the abyss to improve the distance of the arrow. He's completely correct that the use of such a structure would greatly increase the potential distance of the arrow. It also increases the time that wind, etc. could affect the arrow, which has a limiting effect. But, in the best case, it's definitely an idea that would improve the credibility of this part of the OP's story and rationalize a greater distance. Thanks, Martin, for pointing that out! He also mentions tying multiple trees/shoots of bamboo together to create a longer traversable beam that wouldn't require help from the other side. While true, this substantially limits the total length of the bridge as the body weight sag will eventually pull it off the edges and an object that didn't have that sag would have a shatter limit as it must be dropped from a vertical position. In short, I think the arrow is still the best option. Heck, any solution that enjoys the help of the neighboring state is bound to be better than one that doesn't have it. Which brings us to...* You'll need help on the other side Now, the pulley was invented at about [1850 BC](https://en.wikipedia.org/wiki/Pulley). Yes, that's still Bronze Age, but it's a bit much to swallow that someone with a bow and arrow could attach a Bronze Age pulley to said arrow and get it any more than about three meters. Maybe ten. This means that you'll need someone from the civilization on the other side (or a very well-traveled team who sailed around the abyss to be on the other side) who could take the pretty light-weight thread/rope/cable the arrow pulled across, and pulled it... attached to a heavy enough rope (made of either plant fiber or woven leather) across the abyss and tied it off to something stout... like a big old tree. After that, the bridge is just a matter of time and a few lost souls as people slip on the rope We're basically done once you have the ability to move people and materials across the abyss. At that point you could build a rope bridge or, if you want to stretch the tech a bit, something even more impressive. But the ability to get those first few people and materials across, that's what limits the size of bridge you can build. And I'm voting it's 75-100 meters based on suspension of disbelief. If you're talking realistic, then the historical limits of 30ish meters really is your limit. Bronze Age it might even be 20 meters on a good day. But I'm a fan of suspension of disbelief. As for how long such a bridge might last... go rent a copy of [Romancing the Stone](https://www.imdb.com/title/tt0088011/?ref_=fn_al_tt_1)* and watch until you hear Michael Douglas say, "that's not a bridge... it's pre-Columbian art." Pause the movie, and stare at what he's talking about. Then remember that suspension of disbelief is your friend.* [Answer] (Really a comment to JBH's answer but way too long) You need to find a stout tree on the far side of the chasm. Build a kite (fabric on a wooden cross is enough), take two cords and fasten them to the corners (each cord is connected to two corners, crossing in the middle.) Station a crew there to wait for a big storm blowing across the chasm. With four people spread out properly it should be possible to fly the kite across the chasm even with no understanding of aerodynamics beyond recognizing that wind blowing under a tilted surface causes lift. Fly the kite past the tree, crash it behind the tree so that the cords end up catching on the tree. Now you have two leaders and a pulley, you can pull across heavier stuff until you have something that can hold a person. Now the person crosses slung under the rope. This is actually adequate to permit small scale crossing of the chasm--ride-underneath single-cable bridges have existed in the 21st century. You get to decide what plant fibers they have and thus the distance they can cross and note that they'll want to upgrade this if possible as this design will not last since they do not have a good wheel to ride on the cable. Technologically, this requires rope and cloth. It also requires a decent amount of forest on both sides as they have no way of building abutments for the bridge, it will have to be anchored by tying off to enough trees to handle the load. [Answer] Incas lived practically in bronze age and they built rope bridges using grass fibers. <https://en.wikipedia.org/wiki/Inca_rope_bridge> > > The greatest bridges of this kind were in the Apurímac Canyon along > the main road north from Cusco; a famous example spans a 45-meter > gap > > > [Answer] ### Frame challenge: Via Ferrata down and up Assuming the tiny pinpricks of light at the bottom of the crevasse are glow worms, and not dragon eyes or lava... Then the solution at least initially isn't a bridge across, it's a series of ropes going down. Pick the best line with some natural features for hand and foot holds, and chisel more into the rock as necessary. On the other side, do the same for a route up. Or if there are no features on the rock face, chisel sockets for wooden beams and build stairs (well within the capabilities of Bronze Age technology). It's going to take a while to do it, sure, but that's the defining feature of all pre-industrial projects. Even a fully-funded cathedral took decades to build. The Emperor would surely know this, and not expect a quick win. Perhaps even more importantly, the Emperor then knows the nature of the magical crevasse. If it's dark, you'd be lucky to get 10-20m of fall before you lose sight of a rock. It doesn't have to be a very deep hole for you not to be able to see something all the way down, and if the floor is covered with foliage then you probably won't hear it land. [Answer] The Chinese Woven Timber Bridge The bridge can be made of shorter lengths of timber that lock together to form an arch [![enter image description here](https://i.stack.imgur.com/nCeme.png)](https://i.stack.imgur.com/nCeme.png) The longest timber arch covered bridge still existing is the Santan Bridge in Taishun County, Zhejiang Province. Net span: 42m Longer ones could easily have existed but have all been replaced by modern construction bridges. These bridges could be constructed completely from wood with no metal required [![enter image description here](https://i.stack.imgur.com/INSia.jpg)](https://i.stack.imgur.com/INSia.jpg) [Answer] Okay, there are some good ideas with bows/arrows and kites, we might even get a boomerang suggestion. My solution involves the mountainous tribes just recently pacified who train and hunt with large raptor birds. Give them the task of sending over the supporting lines maybe three of four birds at a time. Might even shuttle young boys over and back and retrieve or guide those kites around the trees. [Answer] I think you could do at least 50 meters without any assistance from other side with BIG trunks [![enter image description here](https://i.stack.imgur.com/BhEIz.jpg)](https://i.stack.imgur.com/BhEIz.jpg) if you combine them like this [![enter image description here](https://i.stack.imgur.com/J6sLq.jpg)](https://i.stack.imgur.com/J6sLq.jpg) [Answer] Frame Challenge: do the Distant People want a bridge? do they want to trade and communicate with the Emperor and the Near People? Possibly their immigration policy is similar to the folk on [North Sentinel Island](https://en.wikipedia.org/wiki/North_Sentinel_Island). The first visitor from the Empire may share [John Chau's](https://en.wikipedia.org/wiki/John_Allen_Chau) fate. I'm picturing the Emperor saying: I have just conquered everything on my side of the chasm; I want to bring you Distant People the benefits of democracy and free trade. OTOH, contact is likely to be challenging linguistically: if the Near People haven't had dealing with the Far People, the languages could be as different as, say, Irish and [Dyirbal](https://en.wikipedia.org/wiki/Dyirbal_language). [Answer] There's a related problem of how much overhang can be achieved stacking dominos or bricks or similar. It's fairly obvious that you can build a bridge simply by building two such towers, one on each side, so that they meet in the middle. In principle you can build out to any distance, given a large enough supply of blocks. However the overhang is proportional to the logarithm of the number of blocks, so the limiting factors will be the compression & shearing strength of the material, and the precision of the stonecutters. At some point it would require less material to fill in the chasm. [Answer] I think the thing people are forgetting is that a bridge's purpose is to make it easier to get from point A to point B. Looking at historical records is not going to give the full picture. In most non-fantasy situations there are alternatives to using a long bridge that would be much less difficult and expensive (for example using a boat or just going around). if those alternatives aren't available, the place is just left uninhabited. Its highly unlikely we have seen the full extent of a bronze age civilization's bridge building skills, because there wasn't a strong motive for them to actually use their skills to the limit. You also have to consider the fact that its not just a pedestrian bridge, but something an entire army will have to cross along with their supplies, and it will see heavy foot traffic. Considering these factors, I think this would be a massive military project and they would invest a large amount of resources in building a bridge that is beyond the capabilities of a bronze age civilization from our earth since there actually is no alternative. [Answer] I believe that ancient people could probably build an indefinitely long span if the cost/level-of-effort is relaxed. But only across shallow rivers. Stone arches require them to be able to boat to arbitrary points mid-river, and sink marine pilings. As they finish, they will create a bare area of the river bed upon which they can build a foundation of stone. They build a tower above this at a distance from the last that does exceed the limit of a stone arch (I don't know this number off the top of my head). Scaffolding is erected, and the archway is built. Then they move another 80ft or 100ft or whatever down the river and do it again. It would be risky and expensive, but not beyond the means of some of the ancient civilizations. I think the biggest danger is that they did not have sophisticated understanding of things like thousand-year flood levels. I'd expect them to build it high enough to avoid floods that have happened within living memory, but as we're discovering even today, that's not nearly enough, you know? For examples of what this might look like, see this: <https://en.wikipedia.org/wiki/Alc%C3%A1ntara_Bridge> ]
[Question] [ Crude Oil, is a term used to describe [petroleum](https://en.wikipedia.org/wiki/Petroleum) products harvested from geological formations beneath the Earth's surface. As a fuel they maybe called [hydrocarbons](https://en.wikipedia.org/wiki/Hydrocarbon), hydrocarbons can be found/created in sources other then crude oil but currently crude oil is the primary source on Earth. Would a space age be possible on a planet without crude oil resources? Either Earth after our supply is exhausted or a different planet that never developed crude oil. There are two perspectives here: Could Earth's space age survive the end of the crude oil reserves? Could a space age develop on an alien planet never having crude oil (or similar) energy resources? [Answer] ## Yes...probably What was really important to our development of technology was not oil, but coal. Access to large deposits of high-quality coal largely fueled the industrial revolution, and it was the industrial revolution that really got us on the first rungs of the technological ladder. Oil is a fantastic fuel for an advanced civilisation, but it's not essential. Indeed, I would argue that our ability to dig oil out of the ground is a crutch, one that we should have discarded long ago. The reason oil is so essential to us today is that all our infrastructure is based on it, but if we'd never had oil we could still have built a similar infrastructure. Solar power was first displayed to the public in 1878. Wind power has been used for centuries. Hydroelectric power is just a modification of the same technology as wind power. Without oil, a civilisation in the industrial age would certainly be able to progress and advance to the space age. Perhaps not as quickly as we did, but probably more sustainably. ## Without coal, though...that's another matter You need some abundant, high-density energy source to bootstrap your civilisation up to the point where renewable energy sources can take over. We used coal for this, so I'll use 'coal' as a stand-in for 'abundant, high-density energy source'. If you can't smelt steel or copper in large quantities, you can't build wind or hydroelectric turbines, you can't distribute the power, and you can't release all the labour that goes into farming for everybody. You could use charcoal for a while, but it's horribly inefficient compared to coal. Think of the beautiful, wind-swept, unspoiled hills and moors of places like Scotland or Wales. They're famously unspoiled and untouched... Except that they're not. Those landscapes are entirely man-made. Those hills used to be absolutely covered in conifer forests, but the trees were cut back, in large part to be turned into charcoal. If you tried to fuel an industrial revolution on charcoal...you might be able to manage it, with laser-focus on the goal of getting to renewables, and probably with an entire continent of trees being harvested, but by the end your economy would be teetering on the brink, and it'd be touch and go whether you and your tech could survive. So the critical component is not oil, but coal. You need coal (or something like it) to get your tech base up to the level of using other energy sources - like wind, solar, geothermal, nuclear, etc - on an industrial scale, and you need that tech level to be a space-faring civilisation. If our civilisation collapsed today back to a medieval level, it's questionable whether we'd be able to rise again, because so much of our easily-accessible high-quality coal has been used up. [Answer] Yes but it would be harder. Werrf's answer is correct. You need an abundant and fairly cheap source of energy. Without it technological progress is slow. I think Werrf concentrates too much on replacing coal with other burnable fuels. With modern technology we have replacements for fossil fuel power plants: nuclear, solar and wind, geothermal, and hydro-electric. We can make synthetic versions of fossil fuels if we have enough energy. [This](http://www.zmescience.com/research/us-navy-synthetic-jet-fuel-seawater-0423432/) article describes how the navy can create fuel using CO2 from seawater and power from the nuclear reactors navy ships carry. Fuel is energy rich. Therefore it requires lots of energy to make. In the space age, your problem is expensive, but solvable. In the industrial era, there are no nuclear reactors to power this process. Even if there were, people don't understand the chemistry well enough. Energy can be harvested with windmills, geothermal, and water power. All three of those depend on terrain. Countries with large elevation changes and decent rainfall, will have better access to water power, and therefore will have an easier time in an industrial revolution. Access to abundant geothermal or wind power will provide a similar benefit. Note that in real history, geothermal power wasn't invented until 1904. Possibly this was because people would rather burn coal than go messing around with scalding hot springs and volcanoes. You can't use your water power to fuel a vehicle, unless you can store and transport the energy. The reason we use chemical fuels in vehicles is because they are a very easy way to carry around energy. Until recently, a battery powered car could never have the same range as a gas powered car. You simply couldn't fit that much energy into a battery. There are alternatives to fuel and electric batteries that may have been possible with imaginative industrial technology. Springs store energy, but it is difficult to get them to release the energy slowly. [Compressed gasses](https://en.wikipedia.org/wiki/Compressed-air_vehicle) can run vehicles, but the [pressure vessels](https://www.asme.org/engineering-topics/articles/boilers/the-history-of-asmes-boiler-and-pressure) that store that gas have a nasty tendency to explode. In modern day, proper design codes have made this mercifully rare. In summary, without fossil fuels, energy is harder to get, and much harder to store. An industrial revolution will require people to develop renewable energy generation and storage technologies that our society did not pay much attention to until much later. [Answer] No. It was never about the available technology, it was about the excess of energy required to break through to the next level. Steam engines and vacuum tubes wont get you to space. Every civilization in history that has out-performed its neighbors has done so on the back of 'excess energy'. Something that the civilization exploited that gave it the energy advantage that allowed it to support and maintain the dreamers, the wasters, the entertainers, the artists, the inventors and the local equivalent of scientists and madmen and gave them free reign to explore new and different ways of doing things that did not have any obvious or immediate benefit to society. The vast majority of which could be reasonably considered a total and utter waste of effort. However, you only need one Einstein to move a civilization to the next level, and he started life as technical assistant in a patent office, the perfect job for just another waster. In any society before his (and quite a few after), he would not have been given the opportunity to basically sit quietly in a corner and think of daft ideas. Ideas that took almost a hundred years to prove right and that required the largest and most expensive engineering efforts in all of human history. That we can not even remember a single name from the multiple million other wasters also thinking of daft ideas is beside the point. As a source of energy, coal has been burnt for millennia, but only when it was combined with iron and water in a completely ridiculous and ludicrously dangerous way, by a bunch of loonies who were so rich enough that they could be stupid to excess, could the external combustion engine (the steam engine) be invented to pump water from deep mines. When that steam engine was later matched with the equally absurd idea of a 'factory' process from the likes of Josiah Wedgwood, the result was the alien concept we now know of as the industrial revolution. The western civilizations based on the industrial revolution reached their peaks at the start of the last century and normally they would go the way of all previous ones, excess followed by decline followed by replacement with something completely different, but this time, some fool exploited oil (which at that time was mainly whale oil and used only for lighting) to produce the internal combustion engine. That replaced the horse and allowed cities which had been drowning in horse manure to grow much larger, but more importantly, that source of easily exploitable excess energy was shared among everybody who was interested with the result that a bunch of parallel and equally powerful civilizations that now had excess energy and production capacity at previously undreamed of levels that were motivated to compete with each other for supremacy. The result was the first World War. When people think of oil, they tend to think in terms of the power of the internal combustion engine, but it actually happened the other way around. Having invented the engine, people wanted a fuel to run it that was cheaper and more available than whale oil. Alcohol worked well but give some inventors (with excess alcohol) the opportunity and they will come up with material science. Crude oil became refined petrol and lots of other things. The petrol powered the engines which gave the excess energy which allowed scientists/alcoholics/wasters to think of daft things to do with the waste. Waste that (in the form of plastics) became the basis of the post steam age society. The same daft material science ideas that later gave rise to semi-conductors and modern electronics required to verify Einsteins daft ideas, and get us into space. [Answer] Yes Early steam engines used wood. In the early 1800s the first internal combustion engine was created - and didn't use petroleum > > In 1806 Claude and Nicéphore Niépce (brothers) developed the first known internal combustion engine and the first fuel injection system. The Pyréolophore fuel system used a blast of air provided by a bellows to atomize Lycopodium (a highly combustible fuel made from broad moss). - [Wikipedia](https://en.wikipedia.org/wiki/Diesel_engine) > > > Not having access to fossil fuels might have slowed things down just a bit but we were already well on our way to discovering the basics for combustion engines before we were using fossil fuels. I believe it is eminently feasible that without fossil fuels, plant based fuels would easily sufficed to bring a world the technological levels necessary to achieve spaceflight - especially given that rockets use hydrogen and oxygen and do not rely on fossil fuels at all. [Answer] Others have put great answers here, I want to cover one specific point. Even without fossil fuel inputs, you can create energy dense fuels like RP-1. The process is inefficient, but very doable. The basic process is that methane, oxygen and water are fed into a chemical reactor at high temps and pressures in the presence of a catalyst and what comes out can be refined into diesel and jet fuel. (And RP-1 is just a carefully chosen version of jet fuel.) The methane input can be gotten from anaerobic digesters where sewage is decomposed in the absence of oxygen. This is a complicated and inefficient overall process, but we can literally start with sewage and turn it into rocket fuel. We would need to use solar or nuclear heat to run the chemical reactor on, but it is doable. A South African company called Sasol does this on an industrial basis, so the technology is currently available, not speculative. [Answer] The other answers are good so far, but I don't think anyone has pointed out that there's another way to easily lower the difficulty of getting off an alien planet: just reduce the gravity and/or atmospheric density. A smaller planet with less atmosphere is significantly easier to take off from. Even though the delta-V required to reach low Earth orbit is 9.4 to 10.0 km/s, that required to reach low Mars orbit is only 4.1 km/s. [Source 1](https://en.wikipedia.org/wiki/Low_Earth_orbit), [Source 2](https://en.wikipedia.org/wiki/Delta-v_budget#Delta-vs_between_Earth.2C_Moon_and_Mars), [Source 3](https://i.stack.imgur.com/SmiQv.png) To see what a thick atmosphere does, take a look at the number for Venus: 27.0 km/s! Remember, doubling delta-v more than doubles the mass of the rocket, as it's an exponential relationship. [Answer] There is very little petroleum product in a rocket. For example the shuttle used liquid oxygen and liquid hydrogen for fuel. For energy in space they tend to use solar or nuclear power. The only petroleum used on the shuttle would be plastic. It could easily be made out of vegetable oil instead of mined oil. Getting to the space age would be more difficult. Much of the early industrial revolution was powered by oil. While as others have pointed out "alternative" energy is even older than the use of oil, oil beat all of them for ease of use and cost. Without mined oil the industrial revolution would have been slower in coming and not nearly so easily accomplished. For an alternative setting probably the least alternative history would be liquefied coal as a replacement for oil as an energy source. The most outlandish would require inventing magic batteries so that electricity from alternative sources became viable for more things than it is now. [Answer] I think we're confusing our use of petroleum for technology with our use of petroleum for transportation. Powering technology is a different problem than powering vehicles. Without the portability of petroleum, we could use wind and hydro power easily to power technology. Think of windmills and water wheels for grinding grain - similar setups could easily power the industrial revolution. The industrial revolution would be constrained to areas with access to wind/water power, but it would still happen. The main issue with a lack of petroleum is actually transportation, not technology. [Answer] I think you can, but I can't see any way of doing it short of knowing the end from the beginning. Werrf's answer is excellent in regards to the energy densities of coal and oil that bootstrapped industrialization. Let us say you possessed no coal nor oil but had all of our physics and chemistry textbooks. Could you find a way? Yes. We turn to hydro power. Hydraulic concrete was known to and used by Herod the not-so-Great, which means we can certainly make it given the recipe in medieval times. In my mind's eye I see a place where a river has cut a canyon valley 1500 feet down. We shall dam this. At the beginning we cannot build the whole thing as the bootstrap order is preposterous, but we start on a smaller scale. We head up the canyon or up one like it to find some stream narrow with a great plunge. We build a dam above and a pipe below to drive the generators. It will be a great and colossal work by man and mule to build and start the first high-energy generator, and another great breakthrough to build high density batteries, but once done we shall have power enough to begin mechanized transport. Now we can haul enough materials to make concrete enough to dam the canyon mouth. Long years would pass in its construction and it would be a wonder of the world of its own right. (If the king is wise he will build his castle into the heart of the dam and have such a castle as immune to all assault and easy access to the mountains above.) I have in mind that we can start the generators for the main dam before the dam is very high or wide, but even so the work is slow. Now we sit in an interesting place. We have power, but not really enough. What next? Why nuclear power of course. Uranium ore will surely be traded away by the surrounding nations on the cheap, but other materials to build reactors not so much. But if we manage to win through we shall ignite the reactor and have so much power we won't immediately know what to do with it. But it's not enough. If you haven't seen the end from the beginning the king will think madness when you propose to build ten more of these. You know where we are going to get rocket fuel? Right out of the ocean. We have enough power to crack water for hydrogen and oxygen. With all the hydrogen we can want we can lift great masses to orbit. With so much plutonium coming out of the breeder reactor (I know what I'm doing) we can build the nuclear saltwater rocket (Isp >= 10,000 sec). No coal, no oil, and we're still going interstellar. [Answer] Definitely YES. But it would be much more longer, in different ways and we would live in the different world. ## Energy density is the key At each moment of progress mankind use the most cheap source of the energy with desired concentration. It's hard to imagine modern world without oil. It's hard to imagine factories without coal(or oil). To produce really good iron you need charcoal (or coal or oil). It's hard to cook hot food without wood (except you have oil/coal etc). So mankind have been used many sources of energy: `oil->coal->charcoal->wood`. One could add nuclear power, natural gas, windmill and many others. Each of these resources one could find at surface of planet. Ancient Greece has access to the oil. But.. why they don't use it for cooking? Because they don't need so concentrated energy. When civilisation develops and needs energy with coal density then people build mines. Could we use oil instead of coal? Yes, because [first time it's easy to get it](https://en.wikipedia.org/wiki/Oil_field). I suppose we don't build nuclear power plants as many as coal-fired ones just because we don't need so much energy. Of course without oil it's hard to build spaceship. But it's possible. F.e. [synthetic fuel](https://en.wikipedia.org/wiki/Synthetic_fuel) could be produced from coal. ## Alternative ways Oil is just source of energy. But there are many other ways: hydroelectric, nuclear, solar plants. Without some kind of energy civilisation may change its way (and may not). Some examples * Medieval Japan has lack of resources (particularly coal and iron) and this is the reason they didn't have long sword and full-plate armor. But they have katana as well as nunchuks. * France had lack of oil and built nuclear plants * Some northen people like Chukchi have no access to any energy but wood. They didn't know iron before they met Europeans. ]
[Question] [ A friend of mine, ɹɐqooɟ, lives in a large globular cluster where stellar encounters and collisions are very common. His civilization is a Type 1.8 civilization, having built half of a Dyson Sphere around their star. Astronomers on his planet (a super-Earth of $7M\_\oplus$ orbiting a F5V star) have discovered a red dwarf star that will pass less than $0.8\text{AU}$ from their planet in $6733 \pm 50$ years. This will cause their planet to be ejected out of their solar system, drastically altering the lives of the inhabitants of the planet. As ɹɐqooɟ's civilization has not yet developed stellar engines, they have decided on launching some massive object (not a black hole, they haven't found a way to create micro-black holes that can be stabilized yet) at $70\%$ the speed of light into the red dwarf star, which is $1.050510$ light years away. The impact needs to either destroy the star or redirect it enough so that it will completely miss their star system, causing minimal damage. What should they do? (Please answer before 3/7/6600 at 16:42 UTC-6) [Answer] You've got this the wrong way around. You're trying to deflect an entire star, which engineers refer to as very very heavy. You're doing this to save a planet, which those engineers might refer to as merely very heavy. Any technology capable of measurably changing the trajectory of an entire star would be better put towards adjusting your home planet's own orbit, current or future, to ensure that it remains in the neighbourhood that the current occupants like. If you don't have the technology to change your planet's orbit, you don't have a whelk's chance in a supernova of deflecting a star. --- Lets have a slightly less sarcastic look at an existing proposal for moving stars around, though. A [Shkadov Thruster](https://www.popularmechanics.com/space/deep-space/a10885/the-shkadov-thruster-or-how-to-move-an-entire-solar-system-17000392/) needs similar construction techniques to a Dyson swarm, but basically involves making one giant statite and using it as a solar sail, bound to the star by its own gravity. Upside: your friend might be able to build it, assuming that * they can get to the problem star in good time * there's enough mass available at the destination star * they can get building pretty swiftly Unfortunately, the thrust of one of these things is rather low, defined by $$F\_A = \frac{L\_s}{2c} (1 - \cos{\Psi})$$ where $L\_s$ is the luminosity of the star and $\Psi$ is the mirror rim angle. If we model our star on Barnard's star we have a luminosity of ~1.22x1024W, and if we make the statite a nice hemisphere we have a rim angle of 90° and a thrust of ~2.05x1015N, giving a maximum lateral velocity change of about 1.4mm per second after six thousand years of operation. You should probably start work at least a million years ago, preferably last [galactic year](https://en.wikipedia.org/wiki/Galactic_year). I am now wondering if you could speed things up using your own Nicoll-Dyson laser to warm up the target star a little... If you reconfigured your own dyson elements to make a Shkadov thruster around the much hotter F5V star you'd get 3 orders of magnitude more thrust for only 1 order of magnitude increase in mass... that's a whole 28cm per second velocity after 6000 years! It isn't enough to get you out of the way in time, as you're still only going to have moved less than a quarter of an AU by the time the other star arrives, and it means you can't use your dyson elements to harvest power for other mitigation techniques. --- As a slightly less implausible solution, PcMan suggested a good way to move a planet is with the use of a [gravity tug](https://en.wikipedia.org/wiki/Gravity_tractor), which basically involves bringing a large object close to the homeworld in question and using rockets to stop it crashing into the planet (and a clever orbit to stop the rocket plumes impinging on the planet's surface or atmosphere). Their mutual gravitational attraction will cause the planet to change orbit over time. (PcMan doesn't seem to be writing an answer of their own on this, so I'll tack my take on it down here, but I'll pop it off again if they change their mind) An acceleration of 1m/s/yr will add up to a good 6km/s over time, which should help push it into a position where its year length and location when the star flies by is, if not necessary safe, might be safer. Moreover, it might give a way to correct a surprise escape trajectory into something more comet like, given the occupants time to sort out a more permanent solution. To get this acceleration on a planet of mass $M$ ~4.18x1025kg, we will need a force $F$ of ~1.32x1018N. If the tug is placed at radius $R$ 15000km from the planet's barycenter, it needs to mass $\frac{FR^2}{GM}$ ~1.07x1017kg. That's in the same ballpark as real-life moon of Saturn, [Hyperion](https://en.wikipedia.org/wiki/Hyperion_(moon)). This is a potatoid rock about 360x260x160km in size. Hyperion is a bit bigger than we need by a factor of about 4, so you can slice it up and use the leftovers for reaction mass. Gravity will pull your tug towards the planet with the same force as it is tugging the planet. You will therefore need an engine capable of exerting similar force to keep your tug in space. Having ownership of a partial dyson sphere will give you all the energy you need (50% of the output of an F5V is going to be of the order of 1.4x1027W, which is quite a lot. Even if only 1% of that was captured, you're still doing well) and you should have no problem powering a suitable mass driver firing ground-up moon to keep your asteroid in place. The biggest problem you'll have in the future is the fate of your dyson components. They're very valuable, and very hard to replace, as they'll represent a non-trivial proportion of the easily available mass in your planetary system, and the rest of the mass is going to be flung into deep space when your visitor arrives. Moving them into safer locations inevitably entails reducing the power supply available to your tug. You might need to build an absolutely vast fusion plant on it, and grind up a few ice moons to feed it for the final stages of the visitation... [Answer] TL;DR don't move the red dwarf - move your planet. During those six thousand years, adjust the planet's orbit so that, during the encounter - which will last no more than about two months - the planet is on the opposite side of its primary, farthest from the incoming star. Then, prepare and deploy appropriate measures - for example, massive asteroids and moons in slingshot trajectories - so that the newcomer's attraction's effects are neutralized overall. (That, of course, assuming the stars aren't gonna smash together). --- # Previous answer You don't have very many workable options here. Nothing available to a K1.8 civilization will be able to destroy a star, and "redirecting" it requires either kinetic energy or momentum in quantities, again, not directly available. Accelerating a massive object 70% of the speed of light is not enough to influence a star unless the object is many times a planet's mass -- but, then, you'd have no trouble in relocating your own planet at a much more leisurely pace. It might be possible to alter preemptively your planet's orbit so that the passing of the star will either not influence it at all, or influence it so as to put it back in its original orbit. This, plus the ability of partially directing the motion of a puny planet for the period of the closest encounter, might be enough. You could also deploy the "massive object" in such a way as to alter your own star's motion - something of the kind appears in Asimov's Nemesis. But the target star is too close for that - there's no time. This could be supplemented by the alternative plan of building a lensing statite (or [Bowl of Heaven](https://www.goodreads.com/book/show/13539166-bowl-of-heaven) after Benford's idea) around the incoming star. And maybe also your star. The statite will reflect part of the solar radiation at a single target into the star, causing a controlled flare. This flare will be magnetically focused to impart thrust to the parent star, curving its orbit. Magnetics do not effect work, so you can theoretically focus several hundred thousands tons of matter per second at stellar wind velocities with little trouble once the necessary megacoils have been built. That effectively turns the star into a stellar engine. The thrust, however, is not enough to work in the available timeframe. Concentrating the sunlight from your star into a beam would supply a comparatively tiny thrust to your star; at that distance, focusing on the target star is unfeasible, so "pushing it away" is again not an option. [Answer] I'm going to do some rounding and assumptions. Also usually for orbital mechanics there is a whole lot of mathing for approaches, but for stars approaching each other on an orbit around a galaxy center the approach is practically a straight line. Red dwarves have masses of [up to 0.6 M☉](https://en.wikipedia.org/wiki/Red_dwarf). Let's assume this one is 0.5 M☉. That's 9.945 × 1029 kg. 1.050510 ly is 66,435.38389 AU. Let's round it up to 66,435.8. 66,435.8 - 0.8 means the star will cover 66,435 AU in 6,733 years. That's ~46,800 m/s, slow enough that we can play with this scenario without involving relativity much. That is, the relativistic mass of the star is practically its rest mass. At that speed, the momentum of the star relative to you is 4.65426 × 1034 kgm/s. I could stop here, and let you figure out what kinda mass you need to use to zero that out. But I'll give you an example. ɹɐqooɟ's own planet being launched at 0.7c would have a momentum of 1.22822642 × 1034 mkg/s (considering relativity), which is about a quarter the amount of momentum you need to stop the star. So maybe throw a gas giant instead. Also don't hit the star with a single solid object much smaller than the star itself. At that speed it might penetrate the star and go out the other side. The star would be deformed for a while but would have got back to shape before it hit you. Instead, pulverize your missile so that the shrapnel covers a lot of area. This way you might be able to stop the star. [Answer] A few comments: The question implies that the civilization has just discovered the red dwarf star and is frantically asking for suggestions from far more primitive civilizations. It also states that the approaching red dwarf star is 1.050510 light years away. So I have to ask why did it take them so long to discover the position and velocity of the red dwarf star? This table: [https://en.wikipedia.org/wiki/List\_of\_nearest\_stars\_and\_brown\_dwarfs#Distant\_future\_and\_past\_encounters[1]](https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs#Distant_future_and_past_encounters%5B1%5D) And this graph: [https://en.wikipedia.org/wiki/List\_of\_nearest\_stars\_and\_brown\_dwarfs#/media/File:Near-stars-past-future-en.svg[2]](https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs#/media/File:Near-stars-past-future-en.svg%5B2%5D) Depict past and future close encounters of various stars with our solar system. Note that many of those calculated encounters are many times 6,733 years in the past or future. So why hasn't the much more advanced alien civiliation discovered the approaching star tens of thousands of years ago? It seems to me that a civilzation that advanced will have no trouble with their planet being ejected from their solar system into outer space. Many members of their species should live in enclosed space colonies on various hostile worlds or in artifical space habitats. It is quite possible that their communities on their home planet also have their own self contained ecosystems, to avoid interacting with and damaging what is left of their planet's natural ecosystems. If they already live in enclosed space colony like structures on their homeworld, it won't affect them much if their homeworld takes a different orbit. And to preserve the natural habitat and organisms of their homeworld they can build a giant satellite with fusion powered lights to shine at the surface of their planet to similate the natural light and heat of their star. And if their space travel technology is advanced enough to consider diverting an incoming star, they should be able to move their entire population off their homeworld to other places in their solar system or in nearby solar systems long before the red dwarf star passes in 6,7333 years. And if their planet is hurled out of the solar system it should remain close enough for easy space travel (using their incredibly advanced technology) to other planets and space habitats in their system for many thousands of years. So people who want to move between the ejected planet and any colonies remaining in the star system will have a lot of time to do so. And what about their one half Dyson sphere? If it will not be disrupted by the passing star, it will be a good place for any dispaced persons to move to, since i assume that moving much of the population there was the original plan. [Answer] If ɹɐqooɟ lives in a dense cluster, this is a problem that will need to be solved periodically. That means there must be a better solution. Fortunately, if ɹɐqooɟ's civilization has built half a Dyson Sphere, they have built a stellar engine. They just need to deform the hemisphere enough to form an oblate ellipsoid (so most of the reflected energy misses their own star) and jack up the albedo of the interior surface as far as possible (ideally, they'd make it specular rather than diffuse, but making it bright first is more important). Let the hemi-ellipsoid act as a solar sail to support its own weight, and it'll tow the star and at least the inner planets of their system along with it -- allowing them to alter the orbit of their sun to run outside the dense part of their cluster where close stellar encounters are once in a billion years or so, instead of several times in a million. And yes, this will also work with a Dyson Swarm -- just deploy a solar sail from each particle of the swarm and use those sails to keep all of the particles on one side of the star. It's slower than a solid reflector, but doesn't require dismantling the entire system to get the mass to build with. [Answer] I'm putting this in another answer, because it's very much different from my other one. FRAME CHALLENGE: In a dense cluster, planets that can develop life must be exceedingly rare -- perhaps nonexistent -- because, as I noted in my other answer, close encounters between stars must be relatively common. Current theory has most stars originating in gas clouds that amount to clusters similar to the Pleiades, and later being ejected from the resulting multi-star system. Globular clusters are far denser than these, and the only thing that could keep them from ejecting all their stars over time is if they formed in an organized state -- which would make them more like the disk of a galaxy than the globular shape we observe (meaning any globular cluster is continuously in process of ejecting its population). The close encounters that eject stars from clusters need not be close enough to eject planets from their stellar orbits -- but some fraction of them will be, and the denser the cluster, the larger that fraction. The end result is that the habitable lifetime of a planet in a dense cluster will be much shorter than the lifetime of a star, and many of the planets in the cluster will be rogue -- wandering the cluster, waiting to be ejected even from the cluster's gravitational binding by another encounter (which will happen millions of years after the surface is frozen over). Therefore, a Kardshev 1.8 civilization cannot be native to the cluster, never mind the planet they're on; they had to have colonized in cosmologically and geologically recent time (say, within the past million years), from much further away, and done so without the kind of careful forward checking that ought to be applied to such an endeavor. That doesn't change the answers on what they need to do, but it might very much change the background of the fictional situation. [Answer] Propel the star using fusion rockets made of starstuff. Your railgun projectiles are made of uranium and plutonium. They are designed to undergo fission when compressed in the outer layers of the target star. These fission reactions will produce heat exceeding that produced by the star as well as a shockwave through the starstuff, compressing the material and accelerating ongoing fusion within it. This accelerated fusion will release orders of magnitude more energy than the fission bomb itself. Many of these bombs arrive and detonate simultaneously and synergistically. This reaction does not occur in the center of the star but off to one side. The result - an blast of energetic hot plasma from one relatively small area of star. It is a fusion rocket. The rocket you produce will push the rest of the star in the opposite direction. [Answer] Why bother trying to save a sinking ship, when you (should) already have lifeboats? ɹɐqooɟ's civilization is a post-type-I Kardashev, which guarantees they have the ability to colonize other worlds, and indeed should already have done so as part of a rational strategy for minimizing the risk to their species as a whole from a catastrophic interstellar event like the one you're describing (averting "eggs in one basket"). Instead of trying to save their homeworld, they should instead focus entirely on vastly expanding their colonization project, with a view to relocating the entirety of their homeworld's population (including indigenous flora and fauna) to other, safer worlds. 6.7 millennia gives an excellent head-start on this, as well as terraforming efforts for their new worlds. This may or may not be feasible, depending on how dependant they've become on the energy harvested from their Dyson sphere/swarm, but that will almost certainly be destroyed and/or displaced anyway by the rogue star, so they'll need to make a plan to deal with that loss either way. I'm assuming of course that ɹɐqooɟ and his people have access to effectively faster-than-light transit. If not, colony/generation ships are probably going to be a safer bet (think Mass Effect's Quarians). [Answer] The star will arrive in 6700 years. In that time it needs to be moved perpendicularly by an unknown amount, comparable in size to 0.8 AU. So we need to change its velocity by about 1.1E-4 AU/year. When we take a moment to use factor label notation and check our units like we always should, that works out to: (0.8 AU / 6700 y)(1 y / 3.15E+7 s)(150E+9 m / 1 AU) = 0.59 m/s Our impactor has a speed of 70% c = (0.7 \* 3.0E+8 m/s) = 2.1E+8 m/s. Now momentum = relativistic mass \* velocity, so we can say we need a mass 3.6E-8 smaller than that of the star. Assuming a red dwarf at, say, 100 Jupiter masses, that means (3.6E-8 kg impactor / kg star)(100 \* 1.9E27 kg star) = 6.8E+21 kg. Oh but wait, we need to consider 1/gamma = (1-(0.7)2)0.5 = 71% ... the actual rest mass of the object is 4.9E+21 kg. You need something smaller than Iapetus, larger than Haumea. [Answer] To deflect a star they would have to launch an object, comparable with the star in mass. 70% of the speed of light cannot change the required order of magnitude of mass. So, it would be much, much easier to change the orbit of their planet the way they would want with such energy. [Answer] The civilization can poison the star with matter that squelches fusion. They wouldn’t fire a single projectile, they’d fire a steady stream of refined metals — iron, titanium, just about anything from the lower half of the periodic table that is plentiful in their solar system will do. The first projectile will impact the red dwarf thousands of years before it nears their solar system and with a steady firing rate, and in a few hundred years of such abuse the star will become unbalanced in terms of fusion and gravity and go nova — a safe distance from the civilization in question. [Answer] In terms of distance, 1 light year is about 65,000 AUs. The mass of the star is about 60% of our current star. If you wanted to move its path slightly, you would probably want to smash something very large into it, since the momentum of the system (far away from the superplanet) will be the same regardless. At 70% of the speed of light, there's about a 40% boost to momentum when compared to the classical calculations $\gamma=\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}$. The star is moving at about 46 km/s. According to [this article](https://worldbuilding.stackexchange.com/questions/197207/deflecting-an-incoming-star-railgun-style), a star moving at 106 km per hour could pass at jupiter's radius without much trouble, or about 5 AUs. You need to change its momentum by 1/13,000 of its current momentum (5/65,000), which corresponds to about 0.6 solar masses \* 46 km/s, or 160 km/hour. The momentum of an object colliding with the star, let's say perpendicular to its path, would have a momentum of about 3 \* 10,000 km/s \* M, where M is the mass of that object (in AU). You need that momentum to equal about 1/13,000 times the momentum of the star, or ``` 1/13,000 * 0.6 * 46 = 0.002123 AU * km/s ``` Now, since we currently have 30,000 km/s, we can solve: ``` 30,000 km/s * M_0 = 0.002123 AU * km/s M_0 = 7.08e-8 AU = 1.4e23 kg ``` That's about an object twice the mass of the moon. The least amount of energy required to accelerate an object to 70% of the speed of light is 5 \* 10^39 joules. The sun generates 3.846 \* 10^26 W. Per year, this is 1.212 \* 10^34 joules, and over 6500 years, this would be 7.88 \* 10^37 joules. I'll assume the dyson swarm can capture roughly the same output of energy as our sun, with the F5V star being brighter and likely a bit bigger. You are short the required energy to do this about 60 times, assuming perfect energy conversion. ## Possible, more realistic assisting factor Depending on what neighboring celestial bodies there are, it may be possible to deflect its path more. All you need to do is push is slightly closer to something that has a lot of mass. If, for example, the trajectory it was on relied on it being deflected by a black hole, then moving it slightly closer to that black hole could dramatically change its path, requiring far less energy than would otherwise be needed. ]
[Question] [ I came across this interesting weapon by H.G. Wells, from his novel, The World Set Free, about a special type of atomic bomb that will explode indefinitely. Here is a description on Wikipedia: > > Wells's "atomic bombs" have no more force than ordinary high explosive and are rather primitive devices detonated by a "bomb-thrower" biting off "a little celluloid stud."[9] They consist of "lumps of pure Carolinum" that induce "a blazing continual explosion" whose half-life is seventeen days, so that it is "never entirely exhausted," so that "to this day the battle-fields and bomb fields of that frantic time in human history are sprinkled with radiant matter, and so centres of inconvenient rays." > > > I doubt such a material as presented here would cause such an effect. However, I wonder if there is a possibility of any type of explosive, as long as it is hard in nature, that can cause an effect of "non-stop explosions". Assume that all resources are present. However, total Unobtainium or Handwavium will not be appreciated. [Answer] Having had a quick read of the [source material](http://www.gutenberg.org/files/1059/1059-h/1059-h.htm#2HCH0002), it seems clear that the devices do not explode as such, but vigourously emit heat and radiation sufficient to burn and melt their surroundings. We already know of a way to release the energy stored in a fissile material over a period of time, of course: a nuclear reactor. Regular reactors are limited by their tiresome need to remain solid, and that sharply limits their operating temperatures because even the most refractory kinds of regular matter have a depressing tendency to turn to liquid even before it reaches a puny 4000K. We have a handy term for a reactor whose operating temperature exceeds the temperature limits of its containment vessel and fuel assemblies: a meltdown. The "continuous bomb" therefore is in fact a naked reactor core that when fired up rapidly reaches criticality and promptly melts down into a blob of radioactive metal. The temperature limit now is the boiling point of the fissile material (because it'll be hard to keep a hot gas dense enough to sustain fission), which is 4400K for uranium and neptunium (though a disappointing 3500K for plutonium) which is hot enough to melt tungsten and sublime carbon so there's no practical armour that will keep the stuff out. The liquid reactor will melt or burn or otherwise react vigorously with its surroundings, producing copious amounts of radioactive smoke and ash and lava and being too hot to practically cool with water (as you risk the water disassociating into hydrogen and oxygen, with all the excitement that implies). You just have to wait for the nuclear lava to disperse as it melts through the ground underneath the activation point so that it falls below the density required to sustain fission and then cools by itself, or to get so hot that it boils away into dense radioactive vapour and rains out over the surroundings. This meltdown bomb would probably have a shorter halflife than Wells' weapon, because trying to keep it together to maximise the amount of fission is going to be impractical and so the main energy-releasing reaction seems unlikely to last more than a few hours at the very most, though secondary reactions will keep it hot for a while longer and it will be intensely radioactive for a very long time after it has cooled. In theory the cooled melt (or condense vapour) could be reprocessed to use as nuclear fuel or weapons again, so there's a proliferation risk on top of all the other hazards. With regards to Wells' ideas, his active ingredient, Carolinum, was a name given to a suspected new element that turned out to be no such thing but was merely the already known [thorium](https://en.wikipedia.org/wiki/Carolinium). Alas, thorium would be a bad choice for a meltdown bomb, because it must be first transmuted into a useful fissile fuel (such as U233) by neutron capture and subsequent decay in a reactor (which is what happens in thorium reactor designs). By itself, the common isotope is not fissionable, and so could not be used here. [Answer] You can't really have a non-stop explosion, since the explosion by definition violently propells the exploding stuff away. About the closest you could get is something like the fuel pellets used in a radioisotope thermal generator <https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator> With a high-temperature ceramic container, you could probably have one operate at white heat for quite a while. [Answer] This is quite a coincidence, H. G. Wells having died in 1946. His Carolinum does not exist (and there is no known way of triggering a sizeable nuclear reaction whatsoever by "pulling a pin" in a hand-throwable device). However, there is an isotope of Californium - namely 253Cf - which decays into Einsteinium, then to Berkelium 249, then to the much stabler Californium 249, which slowly decays into Plutonium 241 (all are toxic). Meanwhile, the usual chemical actinide reactions take place, never in so large an amount to be definable as "explosions". Flames are possible, "inconvenient rays" a dead - pardon the pun - certainty. The half-life of 253Cf is approximately 17 days. [Answer] ## Willie Pete AKA [white phosphorus](https://en.wikipedia.org/wiki/White_phosphorus_munitions). This is a material that burns when exposed to oxygen. This makes it extremely hard to "put out," since oxygen is a major constituent of our atmosphere. Has historically been used in explosives, illumination, and smoke generation. If you mixed a large amount of WP with some other agent to control the reaction speed and help remove the heat, you could theoretically build a large block of something that would remain very hot for a long time - probably on the order of hours to days, which is not years, but still pretty long for an "explosion." Bonus points: (if you want to call it that...) If part of the block is isolated from the air - say it breaks off and get buried under ash - it will cease to burn. This chunk will re-ignite when it is next exposed to air, which makes it dangerous over a long period, similar to HG Wells bomb. [Answer] A micro-Black hole might behave like this. To explain: A Black Hole (BH) is a region of highly-curved space-time bounded by an event horizon. Its high gravitational field draws matter in and anything passing the EH cannot escape, so the BH grows with time. However, Hawking Radiation allows the BH to emit radiation. The rate of emission (the BH's temperature) depends very strongly, and inversely, on its size. So a small BH can have a very high temperature. It is conceivable that a BH could achieve equilibrium where the gain due to infalling matter is equivalent to the loss due to Hawking Radiation. Such a thing would look like a continuous nuclear explosion in a space the size of a proton. [Answer] Usually not without creating a lot of force that needs to go somewhere. This has a tendency to disperse the explosion. It blows not only itself out, but also it's fuel and in the case of nuclear explosions, a lot or real estate. You could use the force for propulsion though. This fact is used by the continuously exploding rear end of a [Nuclear Salt Rocket](https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket). [Answer] Island of Stability Metals with High Melting Points and Strength, plus radioactivity Given that we're speculating on a fantasy metal, we can make some assumptions and then deal with the engineering problems. The fantasy is that a metal exists which self-heats, but maintains its strength and doesn't melt. Let's imagine we have a very dense metal, with a very high melting temperatures ( 6000\* C, to make it better than all known materials ) and maintains high strength up to that temp. Let's also say that this metal is moderately radioactive, similar to U-235. Criticality is a complicated dynamic situation, changing as the mass's shape, temperature-based density, and other circumstances change. Let's not model that, because there are many authoritative sources. Instead, let's simplify to say that a 10kg sphere of it simply self-heats up above 5000\* C, and atmospheric cooling will suffice to keep it below melting temp at 6000\* C. Let's surround the sphere in a cubic lattice of the same metal, with the masses adjusted not to enrage its criticality further. Let's make the cube structure 2m across, with multiple crossings in every direction. The lattice is there for several reasons : to keep air flowing around the sphere, to keep the sphere from touching and sinking into surfaces, and to provide more conduction surface for heat. The lattice has to be made out of our super-metal, which is the only substance which can withstand the heat. This 5500\* C sphere is pouring out heat and horrible radioactivity. Everything nearby catches on fire, melts, or vaporizes. You can see the approximate heat effects at <https://what-if.xkcd.com/35/> , as if it's pouring out about 100 MW. If you want to go hotter, you need an even more outlandish metal which supports even higher temps, and you need an even bigger indestructible lattice. Otherwise, it sinks into a lake of its own lava in short order. See the XKCD link for higher power levels. ]
[Question] [ I want to check if the geopolitical system of my world is actually stable. Here's the background on the HAMMER protocol, the treaty that unwound Mutually Assured Destruction: ### MAD gets tested, but doesn't happen: All nations got nuclear ICBMs about 350 years ago. Mutually Assured Destruction reigned absolute for a while, but then about 70 years after nuclear armament, MAD was tested when a country called Vaaison launched a strike on the Gensuran Republic. Surprisingly the world was not destroyed. The countermeasures available were known to be insufficient, but they could hold off an attack for about fifteen minutes before the first missile got through the grid. In this critical time, the allies of Vaaison decided they would rather lose an ally than destroy the world, and immediately broadcast on all channels that they did not intend to fire, and disowned Vaaison. Satellite and radar tech was good enough to observe they were making good on their intent, and not firing. So Vaaison lost all its allies and was subsequently hit by retaliatory strikes from everyone. Because of the overwhelming retaliation, only a few Vaaison ICBMS got through to their target cities before Vaaison's defenses critically failed, and the whole country became a radioactive crater. ### HAMMER replaces MAD This incident lead to the adoption of the HAMMER protocol by international treaty. HAMMER got its name from the phrase "The nail that sticks up is hammered down" which is now often said as "The state that nukes first is HAMMER-ed down). Under the HAMMER protocol, initiating nuclear war immediately nullifies any alliances or mutual defense pacts your country has, leaving you at war against the world. Being the first to fire a nuke makes you the nail, and everybody else hammers. All other countries will work together to annihilate you. Getting caught trying to form an alliance that subverts HAMMER, or making demands with the threat of nuclear war also violate international treaty, but aren't automatic triggers of the full HAMMER protocol. The HAMMER protocol has teeth because as was shown by Vaaison, the destruction is not mutual. The destruction is assured for the instigator, but survivable by the others. ### Conventional war returns: HAMMER ended up being MAD turned upside-down, because the protocol is only activated by nukes, not conventional warfare. About 250 years ago, two nations got in a territorial skirmish over mineral resources, and what started as some fighter jets playing chicken and ground troops harassing each other escalated into war with conventional weapons. HAMMER actually let war happen without fear of MAD. Neither side believed the other would launch nukes first. How believable are threats that you'll launch a nuke over this coltan mine if it would mean total annihilation of you and your people? ### The new equilibrium: Ever since wars have been fought without nukes. They are always lurking in the silos, but nobody uses them. When a nation is losing badly, a leader with launch codes might try to posture and look crazy (or actually be crazy) enough to choose suicidal nuclear rage-quit over surrender, and that threat might lead to an armistice slightly more favorable than the loser could have otherwise negotiated, but other than that, the days of MAD are gone. More than one leader has threatened nuclear action only to be immediately assassinated by his or her own cabinet, who, faced with face-melting HAMMER annihilation, remembered that defending their values to the death had been just a campaign slogan. Could nations go to war under this system without triggering nuclear cascade? Is HAMMER a stable geopolitical state like MAD? What would be the points of failure in the system? Is there a series of moves a key player could make to either seize nuclear dominance or send the world back to MAD? ### Extra background on my specific world: The geopolitics of the world are less like ours in the modern day, and more like feudal city-states. Like territory being taken and taken back in early Europe, people weren't horrified and screaming for all-out war if a part of their outer territory was taken, like Americans would be if one State got occupied. The politics between most nations is like that between early England and France. Always bickering and fighting over things and moving the borders of occupation and raiding each other, but not getting the whole continent swept up in a total war. The people of my world are loyal to the city-part of their city-state, but the other parts of their territory they have learned to be less attached to. Sometimes you own that lesser city or those oil fields, sometimes you don't. You'll take it back next year. And the people kinda like fighting and don't form larger alliances very well. So when nukes were developed and MAD started, tensions were very high because everyone wanted to go back to fighting, it was simpler than politics. [Answer] HAMMER only works if the other countries can get their nukes in first, and completely destroy that countries' nuclear capacity, including nuclear submarines. MAD hinges on the fact that destroying a country does not make you survive. For example, Britain can still strike the capital city in retaliation long after the country has been reduced to ash. Rogue Vaison submarines should still have been able to retaliate. This does not mean HAMMER is inherently unstable: it is however no more or less stable than MAD is, because any opponent can still strike from beyond the grave. [Answer] You asked for problems: * Attribution of attacks: A goes to war against B. Suddenly, A's forward troops within the territory of B get nuked. There are no radar traces of missiles or aircraft, and data on nuclear and non-nuclear artillery shells is highly ambiguous. Who did it? Would A sacrifice a few of their own regiments to get B taken out by cat's paws? * Degrees of participation: A and B are at war. C to Z are concerned, with sympathies all across the spectrum. A goes nuclear. C to F hammer A, G to K make supporting noises, L to Z stay out and question the validity of the data. What now? * Related: Country A keeps a couple of ICBMs in readiness to participate in HAMMER, similar-sized country B lets the missiles deteriorate in their silos and spends the money on conventional weapons. Then B attacks A. * It is different this time: The last implementation of HAMMER was 250 years ago. Since then, the threat of HAMMER has worked. But in the last decades the international order has been polarized, with two distinct blocks in a Cold War. There are unconfirmed rumors that one block has nuclear warplans, and would not hammer one of their own, no matter what. If challenged, they call the question "insulting" without giving a clear yes or no. * Faith in countermeasures: As you describe it, there were ICBM countermeasures to degrade the initial salvo for 15 minutes. (Until the countermissiles ran out?) That was with the technology 250 years ago. What if somebody starts a serious R&D project to upgrade missile defenses? Especially if the state of the art in ICBM hasn't kept pace? [Answer] I don't think it's game-theory stable, because a defecting nation can force the game-ending loss decision in the hands of cooperators: I, leader of Foostanistan offer an ultimatum: I intend a limited nuclear strike on Barbaria to end our long-stalemated conventional war. If, in response, we detect an inbound HAMMERing, we will explode cobalt-laced bombs sufficient to destroy ALL life on Earth. You, HAMMER-abiding nations, have to decide if my limited nuclear strike is worth committing global suicide. (This is not just a two-step MAD, since the HAMMERing players could simply decide to let this one slide, i.e., the "A"ssurance is missing.) Documentary reference: <https://www.youtube.com/watch?v=2yfXgu37iyI> [Answer] This might work if nuclear weapons are very expensive and somewhat limited in numbers (say like India vs Pakistan), since the size and amount of retaliation is going to be limited. But what happens if you have a large power like the Soviet Union or the United States which is geographically large and has a very large arsenal of its own? The US and USSR had thousands of nuclear weapons in order to ensure "coverage" of every important target. Many targets were either hardened enough to require two or more warheads (like ICBM silos and airfields), or dispersed enough so that it would take many weapons to successfully destroy (major metropolitan areas). If a coalition of smaller nations like France and the UK were to choose to use this protocol against the United States, they would discover they have insufficient warheads to provide coverage against the United States, while just a few surviving US submarines would essentially erase France and the UK from the face of the Earth. In effect, instead of raising the threshold of using nuclear weapons, you will have triggered a massive arms race in order to have enough weapons to provide coverage of any conceivable nation. Given the wild disparity between the professionalism of various nations, you also have opened the floodgates to widespread trafficking of nuclear weapons, especially by corrupt third world nations (think of the DPRK selling nuclear weapons technology to Pakistan and Iran. Now imagine if they were capable of selling nukes to Somali warlords....). With all these weapons of unknown provenance freely available, you would also drastically lower the threshold for the use of nuclear weapons. A single device detonated in the heart of a city could deliver a massive blow to that nation, but is this a premeditated attack by an enemy, an act of terrorism sponsored by a third party or even a rogue device that had been somehow acquired by a disgruntled individual? Sorting that out and determining who to strike back against will be exceedingly difficult, especially in a world where every possible suspect is armed to the teeth with nuclear weapons. So you have created a situation where chaos and uncertainty is the order of the day, and the use of nuclear weapons is ironically much more possible than the stable equilibrium of MAD. [Answer] Wanted this as a comment but might fit better here: You ask where it would fall apart. What about tactical nukes? If you allow them attacking conventionally is suicide once you've gathered units anywhere. If you don't allow them its nigh impossible if it was country A, B or even a sneaky strike from C. Then there's O.M.'s question of data and its interpretation. Say country A nukes B but due to the trajectory/closeness and timing (possibly even some anti-satellite strikes) its unclear who fired. Or it IS clear but the country says "yeah well, it was B anyway" to his populace, the world and the majority of its military. Then country B and some of his allies speak up and broadcast it was A... Who are they going to believe? If allies of A HAMMER country B under their falsehoods the rest of the world (who are right) would now need to HAMMER all states who HAMMERED B... All out nuclear war ensues. The only solution I see is an automated response. A system, maintained by all the countries in the world with checks and balances to prevent messing with the system. It uses tons of equipment to monitor the world... And enough nukes to destroy the world. The world then fills in scores to keep the system updated about the status-quo. Should country A try to get the system to HAMMER B through slight of hand, the system will know relations are bad between them and simply nuke both countries. These relations are public, so everyone knows who might get nuked. This also limits how gladly people ally themselves with countries that threaten with nuky things. As an extra precaution, if the system thinks it might fail for whatever reason, it'll nuke countries that have bad relations in case those countries deliberately try to let it deteriorate so they can nuke each other. So countries would have to try and keep good relations and do things like not create large conventional armies that might be a precursor to nuclear war. Edit: this automated entity could be the only one with access to nuclear rods of God. These would be virtually impossible to stop once fired and offer the threat you earned. Even if the nuclear payload deteriorates, the Rod itself would still have an impact similar to a nuke. [Answer] > > Under the HAMMER protocol, initiating nuclear war immediately nullifies any alliances or mutual defense pacts your country has, leaving you at war against the world. > > > In other words... is just declarative! Mutual defense pacts, alliances, and other agreements are only as binding on their members as they deem useful. It's been historically common for nations to decide to honor them or not depending on what's currently more convenient to them. That's part of what sovereignty is all about. Nullifying such agreements gets a "get out of jail free" card to allies-in-name only in multilateral agreements. But if an alliance with the offender still serve their purposes, they can still stand by it. Countries can and do come to support one another in war with or without a formal alliance. This protocol could work in a kinda-feudal world with near-perfect equality, where all significant nations are of roughly equal size and power, where alliances don't persist, and where they don't congregate into larger super-alliances. As for whether that's a direction a feudal world typically goes, EVE Online can be seen as a social experiment ([animated map](https://www.youtube.com/watch?v=JyQOhZYRswc)). To put it short, the world entered a metastable equilibrium with typically 2-3 superpowers surrounded by a less-political "third world". One could even argue that there was a bit of a hammer protocol, "nukes" being cheating at risk of everyone else's resentment. That actually happened (search for "band of developers" if interested) and the alliance was powerful enough to plough through it until it fell apart for other reasons. In a world of super-alliances, a superpower alliance will use nukes when it suits them and there's nothing anyone will do about it. Their enemy alliance is already their enemy, so the hammer protocol has no effect. Their own alliance won't disband over it, because they're held together by a common enemy. Lesser parties won't do anything out of fear. While the HAMMER protocol could work under some circumstances, with the circumstances required it's very likely that not having it would work out to the same outcome. [Answer] Consider the situation in Europe in the 1960s. The Eastern Bloc (Soviet Union and satellites) held unquestionable conventional supremacy over the European NATO nations. The Soviets could have formed up a skirmish line any time they wanted, and headed West, and there would have been ABSOLUTELY NOTHING the West could have done to stop it. Except to break the skirmish line with tactical nuclear weapons. While replying to the attack with strategic nuclear weapons against the Soviet Union proper, at a time when there was no defense whatsoever against such attacks. This is why the West laughed long and hard at the Soviet Union's "no first use" policy, and refused to sign on. HAMMER would be a blanket invitation for the guy with the biggest conventional army to throw one hell of a party, complete with fireworks. [Answer] 1) A special forces raid takes over a couple of silos and fires the missiles. Real cheap way to destroy your enemy. 2) Boomers. Half a dozen boomers hiding out. Before using your nukes you announce that boomers #1 and #2 will fire all their missiles at the first nation to launch against them. #3 and #4 against the second to fire and #5 and #6 fire at the third. [Answer] It would depend upon how their interdependencies played out. Country A may be vital to country C for some reason. So Country A would first seek permission of all Hammerites to attack country B. If country G refused then country A would get country C to threaten country G etc. Treaties aren't worth the paper they are printed on. Politicians tend to be opportunists and under Hammer would package themselves as a victim in any case. Country B would end up getting it either way. ]
[Question] [ What would happen to the fish/animals living in the ocean, if the water became 50% less salty, within the space of three months? Would everything die, or would they evolve very quickly? --- Related: [What if the seas had fresh water in them?](https://worldbuilding.stackexchange.com/questions/14947/what-if-the-seas-had-fresh-water-in-them) [Answer] ## Phase 1: The Extinction Most life in the sea would die out almost immediately. Saltwater fish, invertebrates, and most importantly plants and microbes are finely-tuned for a particular level of salinity and their cells would burst under the osmotic pressure. Sea mammals and reptiles can tolerate the change better, but since these animals tend to be in the middle or top of the marine food chain they would quickly starve. Some of them, like sea lions which are capable of leaving the water might be able to survive for a short time by turning to eating what they find outside the water, but it is unlikely that these specialized fish-eaters could survive for long enough to evolve back into a fully-terrestrial lifestyle. The fact that marine mammals are pretty much all obligate carnivores doesn't help their case either. ### The Deadly Shores Some carnivorous whales and a few salt-tolerant shark species might migrate to the estuaries and beaches, where large prey still lives. They will be hungry and competition will be fierce, with the larger individuals inevitably turning to cannibalism out of desperation. Orcas and bull sharks will plague the shorelines of the world - stay out of the water for a few months if you want to live. Their population will drop off sharply, but a few lucky ones might survive. ### Short of Breath Don't think that living on land means you'll have it easy. Between 50 and 80 percent of the world's oxygen comes not from trees, but from marine algae - the same marine algae that is now dead. Atmospheric oxygen will take a nose-dive. All animal life will suffer as a result, and many will go extinct, starting with warm-blooded, high-energy animals like birds and mammals. A CO2 buildup will accelerate global warming to absurd degrees. If we're lucky, land plants will take advantage of the extra heat and CO2 to multiply rapidly and pick up the slack before we run out of air. Hopefully the next phase will begin before we all suffocate. ## Phase 2: The Green Sea After marine life has all but disappeared, river life would slowly begin to evolve in order to fill the abandoned ecological niches. This would naturally begin with photosynthetic microbes seeking out the extra space in the empty seas. After a relatively short time (perhaps no more than a few months or years, thanks to the extreme ability of microbes to evolve quickly) the seas would once again bloom with algae evolving from salt-tolerant estuary strains. Animal life can once again breathe easy. Perhaps too easy... ### The Neo-Permian Remember how the vast majority of oxygen is made by photosynthetic algae? In our world, that algae is regularly grazed by all kinds of herbivorous animals and microbes. The carbon-overdosed world will suddenly experience a violent shift in the other direction as the new algal blooms pump the atmosphere full of oxygen. Animal life will make a comeback, but the oxygenated atmosphere might present a prime opportunity for massive firestorms to erupt. Also insects might once again gain the ability to grow to sizes not seen in millions of years. Along with the earlier mass extinction of birds and mammals, the world's ecosystem may once again resemble the Permian era. ## Phase 3: The Return Over time, river-dwelling animals would return to the oceans. Salt-tolerant estuary-dwellers and fish capable of altering their own salinity such as salmon would be first, with the handful of surviving species diversifying to fill the empty ecosystem. What is particularly interesting about this new situation is that river-dwelling reptiles and mammals would adapt more quickly to retaking the seas than most fish would, since they are already salt tolerant (assuming they survived the low oxygen levels, that is). Manatees and turtles might be among the pioneer species, leaving the safety of the estuaries to graze the green pastures of the relatively predator-free seas, and crocodiles would likely follow them. From here, it is virtually impossible to predict how evolution will proceed. What is certain is that the world will be greatly altered. This would likely be the biggest extinction event the world has ever known, but life would survive. [Answer] Life would not be able to evolve in this short amount of time. Organisms able to survive the lower salt concentrations (of which there would be some in the ocean) would survive, organisms not able to survive the lower salt concentrations (which would be most of the organisms in the ocean) would go extinct. This disruption to the food chain would cause even more organisms to die out, such as predators dependent upon the animals which went extinct, and this would turn into a major mass extinction event. [Answer] There are [plenty of fish species](http://www.liveaquaria.com/product/aquarium-fish-supplies.cfm?c=954) which can live in variable salinity. And the gradual change in salinity over 3 months would give some the ability to adapt. Some species of sharks, like [the bull shark](http://news.nationalgeographic.com/news/2005/07/0719_050719_bullsharks_2.html) already have the special talent of being able to change from salt to fresh water. Make no mistake, the ecosystem of the oceans would completely change, and there would be massive, massive die-offs. But there are estuary fish, mammals, algae and more, that will have an evolutionary advantage and will be ready to take advantage of it. How much time that will take is questionable, because these estuary systems are dependant on a salty ocean, so many of those may die as well, even with the advantage. It may be decades, hundreds or thousands of years before the advantage is fully taken, or it could be longer. More likely, at first, one species, positioned just right, will have a field day. I would expect the ocean to be filled with a particular type of algae and a particular type of fish that thrives on it, that was limited before by predators (many of which are dead) and a lack of space in a brackish environ. Expect huge changes in ocean currents (less salty water will change that, as well as temperature layering in the ocean) and in weather over-all for the entire world. The ocean determines our weather. [Answer] Since the biology part is well covered by other answers, I added a more physically based answer: A sudden removal of all that salt would make sea level to decrease a bit beacause you removed mass. Of course, that depends on HOW the salt is removed (in example if it condensateds into sub-marine crystals, then the sea level would not change at all). There will be a climate change (temperatures would change winds too etc.) but how the weather is going to change I cannot tell. Also poles would instantly increase the ice surface (low salt concentration increase melting point of ice/water), thus allowing to reflect back more sun energy, helping to lower global warming (a bit at least). All oceans currents would change. Decomposition of certain polluting substances due to life activity would stop/reduce (at least for first years of decreased salt) so there will be an increase in pollution. I also would assume there will be a great increase in Greenhouse gases because all animals/fishs that died into the ocean will decompose and start floating on sea surface emitting gases like methane. So we have greenhouse gases that heat up the hearth, and more ice on poles that cool down, can't say if those 2 effects counter each one or not. Not all life will vanish however, despite most fishes are very delicate and would die even by minimal temperature or salt concentration changes, I guess there are more resilient life forms (or maybe not, I'm not a biologist so I cannot tell that for sure). [Answer] I would expect to see a complete decimation of the entire marine food pyramid. The smaller creatures are very carefully tuned for the amount of salt they deal with. A sudden decrease in salt (over months) would result in substantial death at the bottom of the food chain. At higher rungs of the food chain, which might be advanced enough to adapt to the salinity change, you will see mass starvation. The lack of food will also drastically affect their ability to adapt because they'd be spending their energy finding food. Some creatures would survive, as is always the case with mass events like this. Perhaps they found a pocket of higher salinity, or perhaps they were used to living in brackish waters. However, which creatures survive is not always clear in such events. [Answer] Evolution (adaptation) works basically like this: 1. Species can survive, but some individuals survive better because of trait X. 2. Lots of individuals without trait X die, and lots of individuals with trait X flourish (and the children also have trait X, at least the ones that survive and flourish do). 3. Eventually, the species is dominated by those flourishing because of trait X. Based on this simple definition, you'd need at least some individuals among each species to survive change in salinity. (It's not that the individuals morph halfway through their lives. They were always capable of surviving in this environment). Then the fish weak to the new environment die off, and the ones happy with less salt flourish, become mainstream, and voila, your species is now adapted to the new ocean. The only way to really speed up the process here is with organisms that have short lifespans, i.e. lots and lots of generations. [Answer] As is usual for questions of this kind, the major effect would be an intensive re-evaluation of everything we think we know about the universe, since this would be obvious evidence of the supernatural. There's no way it could happen naturally. The physical effects would be secondary to the societal and psychological effects. [Answer] Particularly in biological systems we don't actually know until it happens and is well studied. organisms have complex genetics & behaviors that turns on/off and we cant totally know (heck mothers cant even predict babies making messes to prevent it), but sure some of the above likely but hardly guaranteed. But its sort of a silly hypothetical situation that isnt plausible, much more plausible is climate linked sitution: if all ice caps melted, salinity will naturally decrease but hardly 50%, more like 1.7% more water & less concentration. Humans could also extract salt but it'd take far longer than 3 months even if it was essentially free money (decades if lucky, centuries realistically). As for volume idk how much it would lower sea levels as claimed, seawater is denser & by removing ions the density could revert closer to 1 so volume may not change as we expect. Geology might shift too, quakes and volcanism due to mass effects which then affects volume & sea level. Lots of feedbacks. ]
[Question] [ Is it possible for an Earth-like planet to exist where the light reflected by the moon is, not as powerful, but close in intensity to daylight? And if so, what would be necessary for it? A moon much closer to the planet? Different chemical composition? Different moon cycle? Multiple moons?? What would be the effect of these on the projected moonlight? Would its spectrum shift towards blue or towards red? Hesitant to tag this as [hard-science](https://worldbuilding.stackexchange.com/questions/tagged/hard-science) as I'm not necessarily looking for exact equations for light propagation, etc... [Answer] I am not sure you understand the vast difference between the brightness of sunlight and moonlight when you ask for moonlight "almost" as bright as sunlight. And in fact the moonlight on Earth is quite adequate for many purposes, so it is possible that your story might work with moonlight no brighter than that of on Earth. The magnitude scale for apparent brightness is a reverse logarithmic scale. The higher the magnitude number, the lower the apparent brightness of a light source. The lower the magnitude, the higher the brightness. A magnitude one magnitude lower corresponds to being 2.512 times brighter. A magnitude five magnitudes lower corresponds to being 100 times brighter. The new moon, the Moon at its minimum brightness, has an apparent magnitude of -2.50, while the full moon, the Moon at its maximum brightness, has an apparent magnitude of -12.90, a difference of 10.4 magnitudes. A difference of only 10.00 magnitudes corresponds to a difference of 10,000 times in brightness. The Sun, as seen in a clear sky on Earth, has an apparent magnitude of -26.74. That is a difference of 13.84 magnitudes. A difference of 13.00 magnitudes is a difference of 126,202 times the brightness, and a difference of 14 magnitudes is 317,021 times the brightness. So as seen from Earth the Sun has a few hundred thousand times the brightness of the full Moon. [Apparent magnitude](https://en.wikipedia.org/wiki/Apparent_magnitude) You might want to ask yourself exactly what you want the extra brightness of your planet's moon for in your story, and then do research to find out how much light is needed for that, and then figure out if it is possible to increase the brightness of moonlight on your planet that much. On a clear night, you can see fairly well by starlight if you are far from man made light sources and the resulting light pollution. I used to go out at night and walk up a hill to a grassy field and look at stars and astronomical bodies with binoculars. I didn't take a flashlight with me to light my way because I wanted my eyes to become dark adapted to see in the darkness better. Human eyes adapt to see better in darkness after a few minutes in darkness. So amateur astronomers don't use flashlights or lanterns, or use only red artificial light, when setting up their equipment to observe the skies, because they don't want to interfere with their eyes adapting to see better in the dark. [Adaptation (eye)](https://en.wikipedia.org/wiki/Adaptation_(eye)) On a cloudy night close to a big city, you can see fairly well by city lights reflected from the clouds due to man made light pollution. On a clear moonlit night you can see fairly well without any artificial light sources. Both history and fiction have many examples of single persons or entire armies sneaking around in the dark. Of course if someone travels by night without artificial light sources they would probably have a higher than usual probability of tripping over something they don't notice or stepping into an unseen hole than if they traveled during the day. But if someone doesn't watch where they are going they could trip during broad daylight also. The light of stars, planets, and even the full Moon, is not intense enough for most people to read by. Even the light of the full Moon is not intense enough to see colors, except that objects may look faintly blueish. If you really want the moonlight on you planet to be "almost" as bright as daylight, then you do have a problem designing a different astronomical set up allowing the moonlight to be almost as bright as daylight, because on Earth daylight is hundreds of thousands of times as bright as moonlight. To get moonlight a thousand times more intense than moonlight on Earth, you might have a moon that occupies a thousand times the area of the sky as seen from the planet as the Moon has seen from the Earth. The square root of 1,000 is 31.622776. The Moon has an angular diameter in Earth's sky of about 29 to 34 arc minutes, so if your fictional planet's moon has an angular diameter of about 916.4 to 1,074 arc minutes, or 15.273 to 17.9 arc degrees, it will have 1,000 times the angular area of the Moon. If your fictional moon is at the same distance as Earth's Moon, it can have 31.622 times the angular diameter of the Moon if it has 31.622 times the actual physical diameter of the Moon. That would make the fictional moon several times the diameter of any Earth-like planet, so if the planet is supposed to be Earth-like and thus have an Earth-like size the "moon" in your story will actually be a large planet orbited by an Earth-like moon. Or the moon in your story could be the same size as the Moon but orbit the planet 31.622 times as close as the Moon orbits the Earth. Other things being equal, that will make it appear to be 1,000 times as bright as the Moon seems in Earth's sky. It should actually be more than 1,000 times as bright since the moon will be closer to the planet and it's reflected light will be more concentrated when it hits the planet. The Moon has an average distance of about 384,402 kilometers or 238,856 miles from Earth. Divided by 31.622 that makes about 12,156.157 kilometers or 7,553.4754 miles, which would be really close to Earth. I believe that a moon that orbits an Earth-like planet that closely would actually be slowing spiraling in toward the planet and would break up into rubble or collide with the planet within a few million more years. Or you could make the moon both larger than the Moon, and also much closer to the planet than the Moon, so that the two factors combined give the moon an angular diameter 31.622 times that of the Moon to make it 1,000 times brighter than the Moon, while still being far enough away to not be spiraling in to its doom. You could also make the surface material of the moon in your story more reflective than the surface of the Moon. The Moon has a rather dark, dull surface and only reflects a small percentage of the light that hits it. So your fictional moon could be more reflective than the Moon. Maybe your Earth-like planet has several large and close moons orbiting it in different orbits. And maybe your planet could have a ring of large moons around it at a fairly close distance. Recent calculations indicate that it is possible for many equally spaced objects of equal mass to share the same orbit, so a few dozen large moons sharing the same orbit around a planet would not be physically impossible, though such an arrangement would be extremely improbable. [The Ultimate Engineered Solar System](https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/) So you could make an astronomical arrangement where your planet has moonlight a few thousand times as bright as moonlight on Earth. But sunlight on Earth might still be tens or hundreds of times as bright as the moonlight on your planet, even if you make the moonlight on your planet a few thousand times as bright as moonlight on Earth. In my opinion, making your "planet" actually a giant, Earth-sized moon of a giant planet may be the way to get the other astronomical body as large as possible in the sky of your world, and thus reflect as much light as possible on to that world. And if you decide that is the case you should look up other questions and answers in this site about stories set on the moons of giant planets. But of course the astronomical set up necessary for your story depends on exactly what you want more moonlight for in your story, and thus how much brighter the moonlight needs to be. [Answer] The sun is about 400000 times brighter than the full moon. That's quite a lot. The moon, despite looking quite white, is actually a surprisingly dingy grey with an average [albedo](https://en.wikipedia.org/wiki/Albedo) of about [0.12](https://www.universetoday.com/19981/moon-albedo/) (equivalent to damp soil). If you painted the moon a brilliant glossy white and raised its albedo to 1, it would be a little over 8 times brighter, which still leaves it 1/48000 times as bright as the sun. (Incidentally, an ideal material for the surface of your super white moon would be ice, which is a little implausible close in to the parent star but not entirely impossible) > > A moon much closer to the planet? Different chemical composition? Different moon cycle? Multiple moons?? > > > None of the above. The apparent brightness of our super-high-albedo moon is related to its size and its distance from the sun. Even if you had ten moons, and each one had four times the apparent size of the moon (so about twice the apparent angular diameter), you'd still be 1/1200th of the sun's brightness, and that's such an astonishingly unlikely and gravitationally unstable arrangement that it isn't really worth thinking about. You'd either need to move much close to the parent star, or to substantially increase the brightness of the parent star. In either case, the apparent brightness of the sun during the daytime would be correspondingly higher, and that means that your planet is going to be roasted and won't be likely to support life (or even an atmosphere, to be honest). If you want something almost as bright as the sun without incinerating the world, you should see about building giant orbital mirrors and have them oriented such that they reflect sunlight onto earth. > > What would be the effect of these on the projected moonlight? Would its spectrum shift towards blue or towards red? > > > Moonlight actually has a slightly warmer colour temperature than sunlight (about [4100K](https://physics.stackexchange.com/q/244922/225554) vs about 50-5800K for sunlight). A perfectly colour balanced brilliant white moon should therefore have a slightly cooler colour temperature than the moon (e.g.: more blue), which isn't what I would have expected at all. [Answer] Salt deposits are more stable, and they are white when powdered. The bright spots on Ceres are hydrated magnesium salts and brine deposits. I don't know if hydrated salts can retain their water content on our moon, but salts like sea water salt are white by nature and have an albedo much higher than that of Regolith. <https://en.m.wikipedia.org/wiki/Bright_spots_on_Ceres> Your setup may involve a shower of meteors made-up of frozen brine hitting the moon and changing its color. [Answer] Moonlight has the (lack of) intensity it does because the Moon's surface (bright as the full moon looks at night, against the black of space) is quite dark -- about like worn asphalt pavement, gravel with tar between the pebbles. To make it brighter, it would need to be covered with brighter material. One fine candidate is ice; a fresh ice surface, if it's finely divided, like snow, could reflect about 5 times as much light as the regolith we see. Unfortunately, ice doesn't stay white like snow over geological time when exposed to space; it darkens and turns red. The undisturbed ice surfaces of Kuiper Belt objects and first-time comets can be darker than the rock dust that covers most of the Moon's face, and redder than a building brick, so if it's to stay bright, it'll need some mechanism to replace the surface every few thousand years or so. Most ices will reflect nearly white -- that is, they won't change the color of the light that strikes them much. Spectrography can tell what the ice is made of, to some extent, by what light it absorbs, but the color of the reflected light will read as white to the eye. [Answer] A Moon could supply a lot of light given the correct conditions. A much bigger moon in a much closer orbit would work, although such a situation might best be described as a double planet rather than a planet and a moon. Such a moon might well fill a large portion of the sky and even when only half lit by the sun would still be very bright especially if its surface where composed of highly reflective materials. I should point out that there are a number of issues with this type of arrangement. Although the roche limit for similarly sized bodies would allow a close approach such an arrangement is unlikely to be very stable and would produce a lot of strange gravitational anomalies. Multiple Moons might sound attractive but in close proximity to a planet multiple large moons would probably be highly unstable leading to a collision. [Answer] Bright enough to see by can mean many things. And the human eye can adapt to a very wide range of brightness values. For example, the brightest noon sun can be 120,000 lux, but a very cloudy overcast day can be as low as 200 lux. Most people barely notice the difference because our pupils expand and contract to keep the perceived brightness roughly the same. A full moon is about .25 lux, but when fully adapted it can be possible to read by moonlight. Interior light generally is between 100 and 250 lux (the latter for a bright office, for example). So if you can deal with the amount of light in a classroom or office, you only need to improve your moonlight by a factor of 400-1000. If your people are aliens, you could also leave the moonlight about the same and simply give them slightly bigger eyes, or their eyes could have a tapetum lucidum structure at the back (that reflective surface that makes dogs and cats eyes glow when you shine a light in them), which greatly enhances their low light performance. [Answer] I did a bunch of math related to this concept on the Gearbox Borderlands (video game) forums. The original post is [here](https://forums.gearboxsoftware.com/t/things-you-forgot-existed-in-borderlands/2119465/100?u=fosley) (go to the bottom of the linked post and expand the "details" section by clicking the arrow). Summary: An Earth-like setup (1) with a moon close enough to be $\frac{1}{6}$ the Sun's brightness would have civilization-destroying tidal forces unless it's tidally locked to the planet. We could handwave the density by calling it a giant comet (3) which makes the tides tolerable, or making it out of fictional, synthetic materials (4) so it has practically no tides. Alternately, we could get a much more plausible setup (4) at 71 times our moon's brightness that still has massive tidal forces, but would only render the outer portions of continents unlivable. By reducing the water mass, you could get more livable area. This is nowhere near as bright as the Sun, but is still bright enough to see by. Using the handwavium from (3), you could reduce the tides to Earth-like levels. Here are the setups I came up with: ### First Setup Moon is 14,430 miles above the planet, subtends 23.3°, and has a solid angle of 0.512 steradians (sr), which is 8000 times higher than our moon. Moon's surface is like Saturn’s moon Enceladus, with a 99% albedo, or 8.25 times brighter than Earth’s moon. This brings the total brightness to 66,000 times brighter than our moon. The Sun is about 400,000 times brighter than our moon, so this moon is about $\frac{1}{6}$ the Sun's brightness, or about 16000 lux. Problems: 1. Tidal forces are 4538 times higher, meaning the tides would literally be miles high, which would destroy everything on the surface unless the planet is tidally locked to its moon. This means the orbital period of the moon is exactly equal to the rotational period of the planet, and also means the moon would never appear to move in the sky unless you moved to a different part of the planet. So some parts of the planet always see their moon, while others never see it. 2. You're quite close to the Roche limit of 6000 miles, which may cause other major effects I'm not seeing. 3. Your day length is about 9 hours, which may or may not be acceptable. ### Second Setup Moon is 41,178 miles above the planet, subtends 0.75°, has a solid angle of 0.00054 sr, which is 8.4 times that of our moon. Again, it has 99% albedo, for an 8.5 multiplier. Total brightness is 71 times our moon, or 1.8% of 1% of the Sun (0.00018). Additionally, the moon is 41% larger, and twice as massive to keep its surface gravity the same. The planet is a quarter the mass of Earth and half the size. Problems: 1. Tidal forces are still 391 times higher. We can cut this down to about 200 by leaving the moon's mass alone, but its still untenable for normal life in non-locked orbits, with waves over 1000 feet tall. 2. That said, you could probably have reasonable amounts of life nearer the center of continents (away from the reach of thousand-foot tidal waves), though your world would be very active with volcanoes and such. I think that once the waves start covering the continents, the increased surface area means the water is being spread into a shorter wave, so it would likely be "only" several hundred feet of elevation that gets submerged twice a day. 3. It's not really "near daylight" anymore, but it's certainly enough to see by. 4. The day length is 90 hours. This was specifically done for Pandora, because the first Borderlands game claims the day there is 90 hours. You could play with the numbers to get something closer to your world's parameters, but you're not going to get much better tides without losing a lot of light. ### Third Setup If we stop restricting ourselves to the Borderlands setup, we can try weird things. Copy the first setup, but make the moon far less dense. Say, the density of a comet ([0.6 $\frac{g}{cm^3}$](https://en.wikipedia.org/wiki/Comet#Physical_characteristics)). It's still about $\frac{1}{6}$ our moon's mass, and probably not physically realizable anyways (that much mass would condense into a much denser ball with gravity). But it brings the tides down to something like 100-200 feet, which would allow life to reasonably exist. And if you handwave the size, you have the advantage that it's made of lots of ice, which is highly reflective, making our 99% albedo more believable. Of course, then you have to handwave the ice seeing as our Moon has surface temperatures well over boiling water. So I'm not sure this is a great solution. ### Fourth Setup Let's use some spacewavium. A synthetic moon made of an extremely lightweight shell might work. It would have negligible mass, and therefore no discernable tides, but would still have the broad surface area needed to reflect lots of sunlight down onto the planet. There are no known methods of constructing such a shell, but it's in the realm of "probably possible". ### Notes on Lux [This Wikipedia article](https://en.wikipedia.org/wiki/Daylight#Intensity_in_different_conditions) lists lux values for different conditions. Our moonlight is 16,000 lux for the first, third, and fourth setups, and 17.5 lux for the second. In comparison, sunlight is about 100,000 lux on a typical day, 20,000 lux in shade that's just illuminated by diffuse light from the sky, 1500 lux on an overcast day, and 40 lux when overcast at sunrise or sunset. Nighttime house lighting is about 30 lux, 50-100 lux is acceptable for safely moving around a strange area without tripping over anything, and 200-500 lux is comfortable for reading. I can navigate in full moonlight (0.1 to 0.25 lux) across unknown terrain without too much difficulty (fences and potholes can be troublesome though), so those "safe movement" thresholds are way above "required to see anything" limits. The first setup would be very bright, much brighter than an overcast day and almost as bright as standing in the shade on a clear day. The second setup would be nowhere near daylight, but still easily bright enough to navigate on foot and so forth. I don't think you could safely drive at highway speeds though. ### Tidal Issues The tide difference in [Cape Disappointment, Washington](https://tidesandcurrents.noaa.gov/stationhome.html?id=9440581) is about 6 feet on average, and seems pretty typical for Earth. The difference at the [Bermuda Biological Station](https://tidesandcurrents.noaa.gov/stationhome.html?id=2695535) is only 2.5 feet, but the top of the island is only [249 feet above sea level](https://www.bermuda-attractions.com/bermuda2_0000bc.htm). This height is pretty typical for areas around the Gulf of Mexico as well. Places like [Anchorage, Alaska](https://tidesandcurrents.noaa.gov/stationhome.html?id=9455920) get really high tides averaging 26 feet difference. Canada supposedly has places with 40 feet average difference. [![Topographic map of United States.](https://i.stack.imgur.com/7So1W.jpg)](https://i.stack.imgur.com/7So1W.jpg) Taken from Pinterest, but the map says it's Rand McNally, so I'm calling "fair use" given that maps at these resolutions are available straight off their online store. If we presume 5-foot average tides, then our first setup would have tides about 4.3 miles tall. That's most of Earth. The second setup would have 1955 foot tides, which is everything in the green and green-yellow zones, or basically the eastern half of the United States. Modifying the second setup to have a lower lunar mass brings us down to 977 feet, or about half of the green-yellow zone and all the green zone. As I said above, I don't think you'd actually get these numbers though, since the water's height is proportional to how much area it covers. Also, if your planet has much less water covering the surface, the relative land area destroyed by tides goes way down. [Answer] This is a brief answer meant to complement others. Some years back I designed portable solar powered lights. I did substantial testing of what could be achieved with various light levels. There was much available information of what was "needed" for eg colour vision, fine work such as embroidery, general hobbies, day to day activities, finding your way around, not being in quite absolute pitch blackness, ... . In many cases the published "required" levels were well above what were adequate for the tasks. Cutting to the chase, for now. More later maybe. Light levels are measured in lux = lumens per square meter. Don't let it worry you. Lux 0.01 - 0.05 - Stumble around in the not quite dark 0.1 - 02.5 - . Bright moonlight 5 ................ Read normal with difficulty 10 -20 .........Read "OK" but poor colour rendition 25-50 ......... Colours reasonably discernible but brighter would be nicer 50 - 100+ .......... Colours Good 300 ............ LCD screen surface full white 100,000 ..... Noonday sunlight So, at 5 lux = 50 x good moonlight with longterm familiarity, and/or biological adaptation, you may be able to do OK. [![enter image description here](https://i.stack.imgur.com/HKXJK.png)](https://i.stack.imgur.com/HKXJK.png) Chart from [here](https://www.researchgate.net/figure/The-scale-of-light-intensities-from-moonlight-to-candlelight-to-sunlight-and-the-range_fig5_287207122) - not otherwsie worth looking at. [Answer] Don't overlook the composition of the planet's atmosphere. One with lots of moisture droplets floating around would diffuse the moonlight and increase the apparent brightness at the surface. [Answer] In short, no. And for the TL;DR version, the long answer is also no. M. A. Golding has given a lot of very good details about why in his answer. What it boils down to is that the moon receives about the same amount of light per square foot as the Earth does (at the upper atmosphere at least) and only a small proportion of that light is reflected from the surface and only a fraction of what is reflected ends up on Earth. It doesn't matter how much you raise the albedo the resultant midnight illumination from a full moon is still going to be drastically reduced from any direct light from the sun. See M. A. Golding's answer for some math around this. Since reflection won't cut the mustard the only option is to have the 'moon' be a light source, and a fairly damned bright one at that. As far as I can tell there's nothing in current physics, astronomy or cosmology that fits the bill. It can't be a small star, it would have to be far more massive than any conventional planet to even get started. Fission is either too slow or way too fast. If the moon were white-hot it would work for a while but the surface would cool rapidly due to the escaping radiant energy and you'd still have to figure out what caused the temperature to be that high in the first place. The only other options I can see are artificial, and those are still big problems. A flat perfect mirror the same diameter as your planet would do it. A smaller convex perfect mirror would look like a smaller sun and deliver a smaller amount. You could have an array of mirrors directing extra light towards the moon, both heating it and raising the surface temperature. Don't ask me how you'd keep them aligned. The torque would probably shred your mirror. And that's without trying to figure an orbit that keeps it out of the planet's shadow. The total energy we receive from the Sun is around 175 petawatts at the 'surface' of the atmosphere. If you cut that down to just visible light - about 43% - you'll need 75 petawatts of visible light to match daylight. You could probably get away with maybe a quarter of that to maintain reasonable light levels on a cloudless night, so let's settle on about 20 petawatts of visible light to satisfy your needs. That's on the order of 1000 times the total global energy production right now. So natural sources are, I'm sorry to say, almost completely out of the question and artificial sources are going to be hugely problematic. You could throw some junk science at the problem or just go full fantasy. White holes? Crazy minerals that tap the zero point energy field or convert dark energy? Spontaneous antimatter conversion? Dyson Swarm transmitting power to light the dark side for the ignorant savages on the surface? [Answer] It needs mentioning that 'moonlight' isn't the same as 'nightlight'. Earth's moon reflects light during the day too but isn't generally significant compared to sunlight. A bright moon would add to 'daylight' as well as 'nightlight'. Generally 'daylight' will be 'sunlight' + 'moonlight' + 'starlight' etc, and 'nightlight' will be 'daylight' - 'sunlight'. So if you want a negligible sunlight so that night and day are prerry close, you want a dim sun and a LOT of stars. [Answer] Consider a world that is face locked to its "sun" - as Mercury was once thought to be and as the Moon is to earth. Make the 'sun' side inhospitably bright and hot and unlivable. Provide some form of thermal circulation system that allows the outward side not to freeze. eg Hand wavium Hot rivers Thermal cycling of water or magma or ... Maybe a hot rain's gonna fall"? :-) Then - piece de resistance - A series of 'moons' that orbit sequentially )or maybe chaotically relatively, or ..., and which provide light from the other-side star. Extra points, Moons are, for whatever reason, in elliptical orbits with fast transition of bright side and high elliptical loops over dark side. Add (implausible) titanium dioxide surfaces if you want really high albedo. Maybe the long passed on fathers set it up ? :-) . [Answer] An alternative way to think about this perhaps is the terrain of the Earth. If you're in a valley surrounded by forest or bush (dark green, no reflections) then a full moon seems very dim. If you're on the top of a rolling hill surrounded by a snow-covered landscape then a full moon is almost dazzling. Apparent brightness is about more than just the source of the light. ]
[Question] [ So here's the deal: my story takes place in modern America in the aftermath of an unexplained event where a runic magic system was introduced to humanity by an unknown entity. Every week a new rune is given to everyone on Earth over the age of 13, and everyone can keep any six of their choosing before having to give one up to make room for the next week's rune. Each rune represents a supernatural power the bearer is capable of using. One of the biggest difficulties of adapting society to this new paradigm is that there's no way anyone can tell what new power everyone's going to get next Saturday at 12:00 PM EST. Mounting concerns about potential unpredictable consequences of future runes, and mounting distrust of the motives of the unknown entity providing the powers, eventually prompt governments to start safeguarding against potential accidents. And the American government decides that it wants everyone off of the roads and on the ground during an hour long period every week, from 11:15AM to 12:15PM EST, to make sure that if something unexpected and dangerous arrives on the rune pipeline one week, it doesn't result in massive, deadly, infrastructure-crippling pileups on all major roadways. The additional Doylist reason for this is because by the end of the first book, one of these runes will cause total societal collapse by disabling all technology that runs on electricity, and the main villain's plan ultimately makes this last way longer than one week, thereby plunging the setting into post-apocalyptic territory. And for various storyline reasons, I want the roads to still be usable, and I don't want to have to wait until massive organized efforts to get the useless cars off of highways can happen before I can do these things. But my main issue is that I don't know for certain if such a law would be constitutional, passable, feasible, or even enforceable in practice. Would it be? Would there be any fundamental issues I'd have to address in order to justify an hour-long period on Saturdays when everyone has to keep their vehicles parked and off of the roads and all planes are grounded? [Answer] Transport networks act as the lifeblood of modern societies, and just like the human circulation system, it's a lot harder to stop and restart these networks than you might think. To explain why, let's start with planes. At any given time around the world, there's around [9,000 or more planes](https://www.travelandleisure.com/airlines-airports/number-of-planes-in-air) carrying over a million people in the air. Grounding them all was seriously considered as a Y2k mitigation strategy until people realised that; 1) There wasn't enough hangar space to go around 2) Restarting the network of flights with their connections et al was going to be a nightmare During 9/11, the USA did actually ground planes, and it caused chaos. Admittedly, part of this was the suddenness of the grounding, but planes were parked on aprons, runways, wherever they could fit. Ultimately, planes cost a lot of money and the businesses that buy them know that the best use of this massive capital investment is having them in the air as much as possible, earning them money. As such, airports and other supporting infrastructure are built around the idea of getting them up and getting them down as efficiently as possible, not on storage. It can be done when needed however, and the 9/11 example shows that. Whether or not it could be done regularly is another matter. It's not so much getting all those planes back in the air at once that is even the biggest issue; it's the scheduling that makes sure that connections still work without massive layovers in one airport or another. Similarly, with trucks in particular, this is going to be more of an issue than you might realise. Most large cities are entirely dependent on trucks to be bringing in food and essential supplies on a constant basis. Large cities consume massive amounts of food, but produce almost none. Could a city survive with an hour's outage once a week? Perhaps, but some industries are time dependent and in the hour bracket you describe, the one that I see bearing the bulk of the impact would be the dairy industry. Cows are milked every day, no exceptions. They have to be to ensure their milk keeps being let down. That means, trucks come to each farm, every day, to pick the milk up. Depending on how far away the processing plant is, it's possible in some instances that the trucks might not make the plant before the driving ban kicks in. Can the farms hold the milk for an afternoon pickup once a week? Perhaps, but at least in some cases this would involve upgrading infrastructure to support that through better refrigeration. It's not an insurmountable problem, but it would certainly have to be planned for. I don't think your core problem is legal; good leaders would be able to explain the risks and then set up the driving and flying 'curfew' with relatively little fuss. Pilots in particular are not going to risk being in the air during an event that could impair their flying skills. I think the biggest issue you'll face is actually logistics. Trucks can park on the side of the road for an hour, planes can't. Schedules, deliveries and connections need to be planned around the regular shutdown, meaning that you need better sophistication in your planning of where trucks and planes are at the point of grounding. The economic impacts are certainly there, but relatively minor, especially when people get used to it. What would happen however is people with logistical planning skills could start asking for a lot more money. Of course, the other consideration here that needs to be managed is whether there is any military exemption. If the US has enemies in your book, 11:59 am on a Saturday sounds like a great time to launch a sneak attack... [Answer] I don't think it would be possible to enforce Some scenarios to consider * People in just generally remote areas where there wouldn't be anyone to enforce the rule * Safety. I may not want to leave my car if I am driving through an unsavory neighborhood * Its an entire hour, Why do I want to be next to my car or just sit there for an hour when its going to be almost impossible for you to make me stop (You would need a lot of police officers walking around the streets but its harder in residential areas). * There might not be enough parking in certain areas (e.g. shopping malls) due to weekend activities being concentrated in those areas. There will be a ton of congestion after an hour when people need to return to their cars and some people might not since they just went off shopping. * Plane Flights, especially international long distance flights would have timing issues. No flights would be able to arrive on a Saturday afternoon as they would need to be operating through your closure time and no morning flights would be allowed to leave since they would also operate though the closure time. * Short distances. If I only need to drive 5 or 10 minutes, I could just ignore the rule because its such a short distance and the perceived danger is extremely low. Sort of like Drunk driving. [Answer] The point is, that shouldn't be something enforced by the cops, but become a moral custom. Look at 9/11 it just needed one accident for people in america get permanently freaked out by the idea of a new attack and were ready to let the government do basically anything to prevent it. What you need to have the population accept and help enforce it is a big catastrophe, maybe some people got fire powers inside of planes and in a single day dozens of planes simply burst out in flames at once. The population would be begging the government to do anything to prevent it from happening once again. Sure, you would have people that would try to break the curfew, but those would be seen by everyone as assholes and possibly endangering others. [Answer] Legally, the government of a country can do pretty much as it pleases as long as it can defend its decisions in a constitutional court and what manner of parliament is available. In the US, an executive order by the president becomes law unless and until successfully overturned by congress or the supreme court for example. So the president, assuming he is confident of his position being upheld, could simply issue an executive order and presto, your ban on road and air travel is now in place. Of course after that you get to the point of enforcement and practicality. As others have already pointed out, such a ban would be highly impractical for several reasons, as well as next to impossible to enforce, certainly without a lot more police resources than the USA has available (and you'd have to exclude the police from that same ban for them to be able to enforce it too of course). That'd stand as a temporary solution. Next a law would have to be drafted and work its way through congress without being modified by committees in such a way that it's unrecognisable from the original proposal in order to make it a permanent thing. That might be even harder than enforcing the ban in the first place. And of course it'd have to be done quickly before someone finds a partisan judge opposed to the president who overturns the executive order not because of what it says but because of who issued it (yes, this happens a lot the last couple of years, it's not uncommon). Of course this judge can then be overruled again by a higher court, until finally the US Supreme Court decides. In the end, a constitutional amendment would be needed to make it really permanent (or as permanent as any law can be), which is a very long drawn out process. And even after that's enacted, the problem with enforcement still remains as big as ever. So could it be legal? Yes. But practical? Not really. Now, a longer ban than an hour might work. Take for example the ban on operating commercial vehicles on a sunday that was in place in Germany for decades. That worked as every trucker knew about it and would seek a parking lot or just go home for the day. Saturday afternoon and evening every single truckstop in Germany and near the borders in neighbouring countries would fill up to capacity with trucks, many of them relying on the business in their restaurants and shops for the income the truckers provided over the weekend to make a profit. As all or most shops are closed on sundays in Germany and indeed saturday afternoons, as are most other companies, there was no real need to have deliveries on sunday anyway. As more and more companies started operating sunday shifts, the pressure to allow trucking on sundays increased and eventually the ban was lifted. Which teaches a lesson: such a ban is best enacted in combination with changes to society that remove the need or desire to travel during that interval. [Answer] It would be constitutional yes. In fact, something vaguely similar was done in 1974, when the Federal Government imposed a [nationwide speed limit of 55MPH](https://en.wikipedia.org/wiki/National_Maximum_Speed_Law). Technically such laws are up to the states, so the general mechanism is that you tie state compliance to their receipt of Federal highway funds. Something similar was done to pass the national age minimum of 21 for alcoholic beverages in the 1980's. However, enforcement of such a law would be left up to states and municipalities, so if its something they aren't also on-board with, it is liable to be widely flouted. For instance, many Western states where there was generally much less traffic and the major population centers are far apart and the new law effectively just picked them all up dropped them an hour further away from each other, hated the 55MPH law, and barely enforced it. I've heard tales of speeders in Nevada during this era getting a $10 ticket for "wasting natural resources." So, like with most laws, you can pass it, but if everyone isn't behind it, that won't do much. [Answer] ## With superpowers available? Absolutely! The key thing here is "everyone can keep any six of their choosing before having to give one up to make room for the next week's rune". Suppose one week the rune is for teleportation. That by itself could make cars and planes pretty much obsolete. Such a useful ability would likely be kept by many people for as long as they could. You haven't indicated what superpowers people are going to be getting with these runes, but it shouldn't be too hard to come up with a rune or combination of runes that alleviates the reasons other answers have brought up as to why the driving ban would be hard to put in place. [Answer] If it weren't for the unique circumstances surrounding the need for a shutdown, I would agree with the majority of answers that this wouldn't be feasible. People like to rebel, after all. But the new runic powers almost completely shut down that line of argument. For people that want to rebel - hey, they just got a new toy to play with. Maybe it won't be particularly useful; but on the other hand, it could be something really cool. You just won't know until you get a chance to play with it; and frankly, you might find that the need to enforce an official ban on driving might prove unnecessary, as people are checking out their new toys. But of course you will have the other end of the spectrum, people that think the runes are evil, and will be insisting on controls, kind of like the transportation ban you propose. I think I don't need to explain why those people will be obeying the ban. In the middle, you have the average Joe you isn't particularly interested in rebelling or controlling other people. The people who just want to get on with their lives. They will probably take a quick break to see what they've got, and then get on with their lives. They will probably be the group that wants to get on the road the quickest - so they found out that their new rune lets them levitate raisin bread, that's cool - now let's find something to distract the kids before the walls are covered in raisin bread. I'd say you can count on 5 minutes before, and 10 minutes after receiving their runes before they're on the road again. Other people have places to be, meetings to attend - oh, wait, it's Saturday. Well, okay, deliveries have to be made. To people are going to be distracted. So they can take a ~~smoke~~rune break, and listen on their radio or watch the feed on their cell phone for the all clear to be sounded that says civilization isn't ending today. That's probably not going to be an hour, though if the law insists, they'll be perfectly willing to doctor their logs to look like they sat out the entire hour. Ah, planes. First things first: there's no way TSA is going to allow anybody on a plane without knowing what runes they have. Since there is no predicting what runes someone will receive, that means no passenger planes will be allowed to be in the air at that time, even before the government considers a ban on all travel during that time. Not that most people would want to be on a plane at that time anyway. And the airlines won't want to risk their planes. Will there be some difficulty storing planes during that time? Probably. But there won't be a complete lack of planes in the air - this window will be perfect for cargo planes. No passengers at risk, and the pilots have clearance to be in the air during this time of high alert. The only thing that could be a problem is if the runes somehow make planes stop working. Then there will be crashes, but the pilots should have plenty of time to bail or land without power, and any crashes will only lose goods, not lives, and should be out of the way. Which leads to essential services. Essential services don't get shut down. End of story. Police, fire, emergency services, will not only be allowed on the street, they will be required to be ready to go. What? Your pregnant wife is in labor? The streets are clear, go for it; when the police stop you and see that you have a pressing need to be on the road, not only will they let you go, they'll probably be accompanying you for something to do. Other essentials, like long-distance trucking, can apply for exemptions if they feel a sufficient business need - but again, they're probably going to be playing with their new toy, so there's not going to be much interest. I mean, yeah, the employers will get the exemption, but that doesn't mean the drivers will be making use of it, unless they're really insistent on getting to their destination now. But all told, the number of the drivers on the road will be cut way back. One last thing - some answers have pointed to historical instances of attacks during expected shutdowns, suggesting that this would be likely to happen during this shutdown. NOTHING COULD BE FURTHER FROM THE TRUTH. Yeah, I'm a militant enemy of the state, and I'm going to launch an attack during the time when we have no idea what new forces could be in play, while my target is on high alert because they also don't have any idea what new forces could be in play? This would only not be an incredibly stupid idea if the runes were almost always lame and useless, in which case nobody would be shutting down in the first place. [Answer] ## It’s widely accepted because mass wrecks already happened The wrong pair or triplet of runes can have unexpected consequences. On a smaller scale, Rune interactions have in the past caused widespread driving mishaps. The first time was the February Massacre, when thousands of semitrucks crashed in an ice storm. That isn't unusual but how they crashed, and how it caused so many fatalities, caused a full-on investigation by the NTSB. Turns out truck drivers had become accustomed to using the Eth and Kall runes together to triple their fuel economy. The mere possession of these runes made you highly sought-after as a truck driver. They also liked to use the Rog rune to help steer their truck. These two acts, combined with how the Fizz rune interacted with a large regional ice storm, stacked with poor understanding of how rubber tires work on ice. Not everyone with that rune combo crashed; it really depended on driver skill (or lack thereof). But then, there was Black Saturday. If a person had Tubb, Kalif, Eth and Lyd runes, and did not replace one of them with Vord rune when it arrived, they wound up with all 5. Their peculiar interaction of those 5 runes drew them toward other people, and clouded their minds if they tried to avert this attraction. This combined cataclysmically with the driving task, with drivers driving their car right into crowds because their mind told them that was the right thing to do. This could not be overcome with will or skill, and the only thing that contained the casualties below 100,000 is that the combination was so very rare. So for society, it was not unexpected that a new rune, or a new rune combining with existing runes, could turn every driver into a menace. So the law forbade driving in that timeframe, and mindful of the tragedies, people got it. It also criminalized not driving exactly, but any consequence of driving was treated as "intent, with malice aforethought". During that hour, a fender bender suddenly turned into a felony malicious destruction, even if runes had nothing to do with it. That put good people right off driving. ## It also became a maintenance window When the paving companies figured out how to chisel up and repave a city block inside a 1-hour window, that settled the matter. Now you wouldn't drive anyway, becuase you couldn't count on the road not being blocked by the giant machine resurfacing it. [Answer] Why would the government have to? Everybody is psyched about the new abilities they might get and sure as hell wants to try out, what Santa brought this week. Sure, some doofus' don't care, but those three people can't do much harm when driving around. [Answer] Yes, it is trivially done. In fact the power to impose a nation-wide curfew, once a week for an hour, is granted by one of the runes in the hands of the members of the cabinet. We can even say that it is in possession of the President, to make things easier. It was the first rune that this character received, and they are very fond of it. [Answer] When you change the rules, the rules are going to change. A lot of answers so far talk about how this would be problematic, or possibly even illegal, in today's society, but this book posits that we are no longer in today's society. As President Lincoln famously put it, "the Constitution is not a suicide pact," and one of the things Americans do best is solve real-world problems. I'm reminded of Brandon Sanderson's The Reckoners books, set in an Earth where some mysterious entity is handing out superpowers, with a twist: there are no superheroes, only supervillains. Whether it's a "power corrupts" type of thing, or someone is consciously giving power only to the worst of humanity is not known, (at least not at the start of the series; stuff does become more clear as it goes on,) but what is common knowledge is that everyone who gets powers becomes a villain that the good guys have little recourse against. The books mention the "Capitulation Act" that the United States had no choice but to pass, which gave supervillains complete legal immunity for their acts. It's implied that this happened because the alternative was to get all of the law enforcement / military / whatever other personnel killed trying to enforce the laws against them. And as ugly a solution as this is, in the context of the rules having changed so completely, it was probably the least bad alternative. [Answer] When asked, Americans will step up and do what is needed if there is a situation that they believe is a national emergency. I feel it is entirely possible with the right motivation, but it changes everything. It's not a matter of stopping planes and automobiles, you would also need to stop ferries, ships, boats, mines, factories and other operations involving heavy equipment. Even if we all knew we needed to stop at 12:00 for one hour, it's getting to the point where we can bring things to a halt. You can't just power down a factory or a steam generating plant for an hour. Taking pressure off boilers and closing valves can be a very time intensive job because if you close a steam valve the wrong way for that situation, it might eat through the valve making it impossible to power down until the boiler is off-line. Replacing a 36" valve is a weeks long process. Some factories and plants take days to start up and shut down. As an example, you can't just stop and start a nuclear reactor and the motors that run it will still need to operate. Some power generating plants work with liquid sodium and when it cools, it becomes a very intensive process to melt the sodium to get the liquid to flow once again. You can't simply stop a tugboat under tow. There is the issue of tides and currents, so even at a full stop, they will still be running to hold that position. The same with ferries and ships. With time you can get all of these things to coordinate a stop, but you may have to fundamentally change how the US works. Thursday and Friday become power down day and power up day, which would need to move into Saturday. This would change our pattern of resting on Saturday and Sunday. Good luck with changing everything. With all of that cooperation, you might end up with a better society as an end result. [Answer] From a narrative stand point I see no major issues with this. Governments can impose curfews and transportation restrictions as they please. With such drastic change tho surely comes civil unrest. Human populations especially us citizens of the US do not take kindly to disruption in our daily routine of any kind. If the people are not given a proper explanation for the need of the curfew/Transportation restriction then you almost certainly will have rebel militias sprouting like wildfire trying to combat restriction placed on them, for reasons ranging from distrust of any government actions to simple frustrations with the inconvenience of the mandatory auto mobile shutdown. As some side notes you may need to include information about the boom of public transportation during such shut downs. I can for see a possible final conflict between the central government, and rapidly growing militia groups. This could result in massive loss for two sides who are essentially fighting for the same goal of public safety. So to close your original question yes, an enforced hour on Saturdays void of automobiles is feasible, but likely to cause future problems. ]
[Question] [ Youtube, Vine, Twitter, Tumblr, 4chan, Reddit, Stack Overflow, heck, even Github or Slashdot...all these online, primarily social sites have been able to build up not only tremendous communities, but "celebrities", sometimes even actual stars as well. In a pseudo-cyberpunk setting in a world, the community of a website organized resistance against an oppressing, secretly global power, for freedom of their entire planet. Partially, it happens, when the oppressors build an AI that accidentally, takes control over the "internet" and destroy every major nation by tactical nuclear strikes. Now, assume this does not exterminate life in general, nor human race itself - it's possibly the matter of an entirely different question, but I have plans. Anyway, assume what happens after that is the "cryptolock" of every computers, the end of some towns and a gigantic recession, but humans remain to live on. There's a chaos never seen before. Several "nuke-harmless" countries collapse anyway, in the destabilization. In my setting, the remaining members of the community, from all around the globe, gather in the same town and start establishing a state. (let's call it Future Empire, if it's relevant in any intent). After this, thy become the major state organization with technocratic and humanitarian aims. My question is regarding about its likelihood. An online community is definitely not such a serious task to maintain like an entire country. Though, there are similarities that I think are beneficial for the starting conditions: * at least within the original members of the community, there are respected individuals. Hierarchy is easier to establish. * Admins, mods and similar people may have experience at solving confrontations and handling human relationships. * A community that is unified enough shows confidence, stability and safety, and it is possibly attractive for poor, starving, desperate, rebelling, etc people. I can also see the disadvantages of this situation, especially in the potential lack of experts in certain vital fields - is it possible to solve? TL;DR - can Stack Overflow build up a country? My story does not take place on Earth, but if it's hard to give a general answer, then we may focus on a "this happens on Earth" scenario. [Answer] ## No. There's a huge difference between an online community and a physical one. We log in, chat with people we know as @Katamori , etc., then - most of us - log out and go about our real lives. While I might respect a SE mod's opinion on these sites, why would I respect their intervention in a private matter? Who are they to me, really? And the answer is no one. I have a family. I have good friends. Maybe I'm a member of a tightly knit community, etc. I will always value their opinions over someone whom I have never even met. Furthermore, maybe you've noticed that our users come from every corner of the globe. After a nuclear apocalypse wipes out every major city center on the face of the planet how exactly are you going to have these people all communicate, agree to drop everything, and travel to this magical place where you intend to found a nation? People are driven by a sense of community, yes. We're social creatures. However, with survival in the balance, golden-age niceties such as politeness and political correctness go out the window. And online communities are not built around survival - they (the good ones anyway) are built around respect, and offering people a place to share their thoughts without fear of abuse. Someone who might moderate a debate in chat, and ban a rude user is not necessarily the person best suited to lead a group of people into a barren, nuclear wasteland. I'd also like to point out that founding a "major state organization with technocratic and humanitarian aims" is not realistic in a post apocalyptic scenario. The world is ash and cinders, a malevolent AI is probably building an army of T9000's in some underground facility somewhere, and I can guarantee you that large packs of scavengers and bandits are out there doing their thing, armed to the teeth. And you're worried about humanitarian aid? How about just finding food, water, and a place to sleep? How about hanging on to those things, not to mention defending your life, and the lives of your family and friends? At that point you will have way bigger issues than contacting your online friends, setting up a place to meet, then announcing that you've formed the nation of Stack Exchangia, and will be benign overlords of a utopia born on the stack exchange forums. Number 1, no one will be listening to your proclamations of peace and equality, and 2, you'll be too busy dodging bullets to finish your speech. [Answer] # Nope. I am a moderator on Stack Exchange. If you put me in a position to control a country's military, infrastructure, and economy, the government will collapse within the week and we'll all die. Moderating internet trolls and the good-natured bunch of y'all that make Stack Exchange sites tick is one thing. It poses its own unique problems, and there are some analogies to real-world government: * Fighting spammers with our ban-hammer, Mjölnir (the military) * Tagging and retagging and re-retagging and organizing content (maintaining the infrastructure) * Deleting poor content and suspending folks who break the rules (law enforcement) * Migrating questions and building inter-site relationships (foreign policy) However, all of these require a limited skillset. Sure, you need to have maturity, a good temperament, commitment to the job, and a fairly strong conscience, but I don't need to know the ins and outs of economics or how troop movements work. I click on boxes and the computer does the rest. Boom. That's moderation. I write a couple paragraphs in a meta post. Boom. That's leading. It's easier to lead on the Internet than in real life, and it's easier to keep law and order on the Internet than in real life. There are firm systems you have to stay within purely from the perspective of the UI; they're there to keep folks in line. After an apocalypse, it's a lot harder. There are no restrictions, no system to give us the tools to lead and follow those who can lead better (not that with them we'd be any more successful). And, frankly, most of us don't have the skill set to keep a society together. We have disparate skills - especially here on Worldbuilding - but we don't have enough, and we don't have the expertise to put them into practice. [Answer] # No. Something like this was tried several times and it failed. In Russian imageboards, there's idea of 'Битардск' ~ '/b/-tardville' - rural village squatted by anon commune - or collectively rented property. On one hand, swapping society you're not comfortable with to one you are comfortable with looks neat. With some amount of planning commune may even seem self-sufficient, in theory. In practice, these tries usually fail. Turns out stable online society does not translate to stable offline society. Participation in online communities is voluntary and there exists a selection bias. Some people are way more likely to participate than others and you're going to have surplus of those and deficit of people who are not likely to participate online. For example, skillsets of people in StackOverflow community are heavily biased towards programming, which also means that they are biased against stuff that is pretty far from programming. Well, problem of skillsets can be solved. However, there's another problem: personalities. People usually get a healthy-ish dose of personal interaction offline with different people, and some interaction online with some people. Online societies in this setup are not expected to provide all meaningful interactions and are not tested for their ability to do so. Even if we speak about imageboards that can occupy majority of user's social interactions, they're not going to translate into offline societies well. Same thing with supply and demand. If you have oversupply of people who are good at discussing things you're likely to lack in department of people who can actually get stuff done. There could be some bonding thing that partially solves the problem by forcing people to do stuff they won't do usually. However, online societies don't provide that. Drugs, for example, do and sometimes attempts to build a b-tardsk devolve into a drughouse. However, drugs are just a filler for when lifestyle and society does not provide things you need. Cults provide bonding too. Although they are not online, I'd expect cult-based society to outperform online-community based one, provided that both are trying their best to get by. There are cults (A outcompetes B, A competes for the same resources => B is going to have a bad time). Online society is also not tested for ability to provide stuff offline society is expected to. For example, sex life. Attempts to round up some willing anons and build a community fail spectacularly if there are girls in the community. Competition for sex generates ridiculous amounts of drama. Same thing, although a bit delayed (because Overton window is inert) happens with groups with gays or bi-curious people, and you don't have any realistic way to prevent that. I've heard of only 2 semi-successfull attempts - 1 became a drughouse but people who remained there were quite OK with that, and it lasted. Another operated as a web studio, but people there knew each other for some time before and that course of actions was planned. It lasted for some time too. Speaking of larger societies, I suppose it's even less likely. If communications are disrupted, gathering people from the whole country is going to take years and lots of resources and is not guaranteed to pay off, let alone global project. Yes, some centralisation would be good, but not a global one. Especially when somewhere out there is a thing that would gladly nuke that newfound city. I'd expect Amish to outperform any online-based community by a wide margin and hence I wouldn't expect online-based community to seize power in Future Empire even if there was built one. [Answer] Shift the plane of thought and maybe then your answer might be *Yes* If this "bomb" instead of killing us, knocked us into a virtual environment, where all users of SE suddenly become Avatars in Minecraft.. we quickly recognize that we all need to light hundreds of torches and build big walls around ourselves.. then we discuss what happened? and then rebuild society? within the virtual environment, and the Mods would discover some pre-existing benefits in this new world? then yeah.. maybe. [Answer] ## Yes. The "no" answers seem to be trying to prove a negative about a hypothetical society based on current websites, but this is a post-disaster, alternate Earth setting we're talking about. One with its own societal conditions, and an evolved online culture. It should indeed be possible to build such a society, depending on the premise, provided we understand the question is not "can *StackOverflow* build up a present-day country". It is "can an online forum, *e.g.* StackOverflow (or any number of somewhat-different websites left over by the Old Ones, i.e. us) build up a country, defined as any possible or unforseen means of government in a realistic, *future Earth* setting". The question cannot be disproved by citing the limitations of StackOverflow itself. The "no" answers to this question suggest a fairly limited interpretation of what a "country" might look like. Sociologically, a nation-state, like a blog, is a human construct -- not a social contract or social fact, not something immutable and innate to human beings, but something intellectual that proceeds from human desire for structure, alongside numerous other, alternate means of societal organization -- temples, tribes, corporations, feudalism, etc. By the same token, the "No" answers are predicated on an assumption that the Internet is one specific type of thing, and that other forms of organiziation on the Internet are not possible due to the nature of humanity, trolls or whatever. This is based on observation bias. The Internet would be extremely different today had the laws written in the 90s or the culture of 90s-era web communities or the intentions of people who wrote the code for the Internet been different. It is safe to assume the Internet of the post-apocalyptic future would also be extremely different. The Internet is a tool, one that mirrors offline methods of organization. The behavior of people on the Internet is a (dark) mirror of offline culture and behavior. Both the State and online organizations are means of organizing societies from afar. In most nation states, the average citizen has little or no face-to-face relationship with those who govern them. In many ways it is a consumer relationship. To say that an online community can't run a society because then we wouldn't have the face-to-face relationship we enjoy with our local leaders, is in some ways an idealistic straw-man. It's true that such a society may be different, maybe less democratic (but not necessarily) than a town-hall democracy, but we don't live in a town-hall democracy today (and many people constantly say that technology has rendered town-hall democracy as impossible as online democracy, but we have no proof that either are impossible). Moreover, the 30-year existence of community listservs, many of which are used to rally citizenry at the neighborhood level and the people not on the email list don't get much of a say when they show up for the town-hall meeting, proves the "Yes" argument by example. If I were writing your story, I would focus on the concept of the "Internet of things" and how it relates to your future society both pre- and post-apocalypse. I would also read "How The Irish Saved Civilization" and its influence on so-called digital scribes who seek to preserve knowledge from data decay using the Internet (which was designed first and foremost by ARPA to preserve data in the face of a nuclear holocaust) to counteract the effects of decreasing lifespan of storage media (from books to much more fragile magnetic drives). Also keep in mind that the structure of the online community you wish to use is important. I would take the approach of sci-fi and fantasy novels that compare several different societies by having the protagonist interact with several different communities, some of which are successful, some of which are unsuccessful, some tyrannies. You might also look at articles by respected psychologists on how social networking is rewiring the brains of young people -- not necessarily for the better, but extremely relevant to this question -- by making reputation something that carries with them throughout adulthood, where there is no break from the pressures of online reputation because they are always online, carrying it with them, and their words are not ephemeral. Also read about how China plans to use a universal "online reputation" metric to evaluate all its citizens, giving them more or less rights accordingly. At the opposite extreme, I would read about people who are heavily invested in online subcultures and their pre-existing impact on electoral politics -- the Occupy movement or the alt-right, for instance. Twitter might be used as a model for the power of the (flash) mob, as several movements have used it as an organizing platform to overthrow governments, but also as a distraction and a sole means of communication. You probably couldn't govern by Twitter, although the current US leader will doubtless try. A society run by Twitter might appear as an "outward-facing Panopticon", an inquisitorial society where people confess their thoughts minute-by-minute, and the most influential thinkers control the discourse by virtue of who is listening to them. Imagine a series of towns run by an Internet of Things, possibly the sole source of wisdom which survived the war (as all books have been burned up, and the written word is priceless) or people forgot how to read before the war happened and had to re-learn it, (making the online word priceless) due to a universal audio-visual culture. A town run by an anonymous message board with ephemeral posts would create a radically different society than a town run by a social network with rigidly enforced reputation heirarchy in which your comments gather you more reputation which you can exchange for credits, for instance. Imagine that currency has been replaced by credits because paper money was replaced by online credit, brick and mortar stores disappeared, manufacturing jobs were automated and disappeared before the war, and then access to credit and goods became limited to certain sites. These sites became distributed on local peers, which is how they survived the war. Only a few peers survived, resulting in a geographical focus for certain sites. Some sites are more geographically focused than others -- perhaps the people of one community do not know each other face to face, maybe never even go outside because of radiation or what-not but communicate only online -- online organizing becomes even more important. For others who know each other face-to-face it perhaps becomes oppressive, a form of social status, or a sort of techno-feudalism perhaps. Or perhaps the Internet of Things enables a small group of outlaws to maintain a shadow government which impacts the real world, but is only visible online. Take careful note of online currencies and how those work -- including the phenomenon of "farming" goods for credit on multi-player virtual-reality sims. Certain forms of information might be power (and worth farming for credits) or online goods (and reputation) in a world with limited sources of income, where all goods of value are manufactured by machines that humans don't know how to operate, or pre-date the war. In real life there are techno-utopians who have called for ordinary democracies to run elections, town hall meetings, citizen participation entirely online -- that is a more positive spin on it. Any cyberpunk author would answer *"yes"* to this question, provided you were imaginative about it. It's an intriguing basis for a story and there's a million different ways you can go with it -- which alone disproves the "no" hypothesis -- unless you're a modernist asserting that there's only one form of ideal government -- or a postmodernist asserting that the media fundamentally distances us and prevents us from forming a community to begin with. Really, the "no" answer to this question asserts that it is impossible to use technology to form a government, and we have no evidence of that. Or it asserts that it's impossible to modify a whole bunch of different sorts of online forums to substitute for (or run) a viable face-to-face community, again we have no evidence of that. (and some evidence that it is possible). Or it asserts that government is inherently based on a monopoly on physical force and there is no other analog or competing structure that can serve as an online model. Certainly the existence of entirely innovative types of forum, invented relatively recently, such as the wiki (or the contacts-monitoring social-media platform) militate against the notion that it's impossible merely because you couldn't do it on an existing site, such as a Q&A site. If society were trapped underground and the only means of communication were StackOverflow, SO would quickly be *adapted* to serve the purpose. The question is what form it would then take. [Answer] ## No I think the core issue from the start would be trust and identity. It turns out that this "Joel Harmon" account I use is a clever misdirection on my part. I'm secretly Joel Spolsky, founder of Stack Overflow. As such, I am the God-Emperor of Stacklandia¹. The first order of business is for me to figure out who among this crowd of thousands (millions?) is an administrator on one of the sites, and who is lying to gain authority. I need to get this figured out as quickly and painlessly as possible (so they can begin organizing construction on my statue²). How many users of SO can you pick out of a police lineup, much less a crowd? My number is 3. If I can trust avatars, that number goes up to maybe 6 or 8. Even then, though, the original question posits the wholesale destruction of all major nations. At a guess, that means half the community members are dead to start with anyway, including the moderator population. The question also posits the cryptolock of all computers, meaning there's no way to, say, post a picture of yourself to verify your identity. Taken all together, I think there would be enough holes in this new hierarchy that they'd be filled in the traditional way. That is, the most forceful personalities would more or less end up in charge. ¹ I'm sorry, Mr. Spolsky. Please don't ban me. ² Too much? [Answer] YES - Depending on the community It's been my experience with several forums that members on there will sometimes organize a gathering or have several members meet with each other. My main example (which might be biased), is an online community such as AboveTopSecret.com - It's built up of people that believe in everything under the sun, and I (as a member), have made several friends on there. A community such as that site could potentially survive for the following reasons: 1. Members come from all walks of life - there are engineers, writers, survivalists, scientists of all flavors, and supposedly ex-FBI/CIA/Police. Due to this, most of the gaps that would be absent can be filled easily. 2. Most of the members are clustered around a specific country (IE: There are lots of members in the USA alone). 3. Most of the members, like the rest of us in society, know how to "agree to disagree". While they do have opposing beliefs, they can coexist. 4. There's a healthy number of members into survival, and making do with what they have around them. Mainstream sites like Twitter or youtube would struggle more because: 1. Unless you have a large number of Youtube posters that work together, each person is more or less in their own bubble/channel. That guy that does science experiments does not talk to the guy giving a lecture on finances. 2. A large number of people on those sites devote themselves to something that would not help out the community. Those cute videos of cats might make you happy for a few minutes, but that's not going to help you build a society. 3. Many of the people on those sites have never met in person. On youtube, all we really see is what they present in front of the camera. Same with twitter: We see a screen with thoughts that might only be some of their thoughts. Maybe those people are brilliant only when they are alone, in their rooms doing this stuff. At least on a forum, you have people with a common interest constantly interacting with one another. In short: I think it would be possible with the right forum, but not realistically possible with a place such as youtube or twitter. [Answer] To me the answer to this question is dependent on the answer to the following question: do you consider the idea of a country to be tied to geography? If country is tied immutably to geography, then no, an online group, regardless of where the respective members are located, could never be a country because there is no geographical data that describes the location of the Internet. Something online is by definition digital and essentially anonymous, not tied to any geographic location. Each individual piece is stored on a hard drive somewhere, and that hard drive does have a geographic location, but does that location necessarily matter to people who are accessing that data while viewing a website? Not on the whole. If country is not tied to geography in any way, then yes - an online group of any kind could form a country by creating a system of government and defining who the governed are; who are the members of the group (citizens), and how does one become a citizen? [Answer] I give this a resounding...maybe It's extremely implausible, but certainly not impossible. For example, if the community is `worldbuilding.stackexchange.com`, my answer would be hysterical fits of laughter. On the other hand, if the community is `survivalist.stackexchange.com`, then...maybe. There are certainly other factors that would play into it, such as: * Population density of the group within a given geographic area. For example, there are likely more members of our hypothetical `survivalist.stackexchange.com` in some areas of the United States than others. * Do the members of the group have theoretical or practical knowledge? In other words, are the members of our group theoretical survivalists, or have they applied their knowledge and acquired the skills? * Are the group members ready to deal with real-world issues? I.e., in the event of post-apocalyptic communication issues, are they prepared to use alternate means of communication, such as amateur radio? After some more thought... The reasons I cited above (as well as the reasons cited by others), don't matter much to the OP's question. The real questions that the OP needs to answer as he is creating his world are: * What post-apocalyptic survival skill does this community have that makes them uniquely (or best) qualified to govern (or even just the first to establish a viable government, whether it's unique/best or not)? * If the government of their community is accomplished through virtual means (i.e., in a new, hypothetical `government.stackexchange.com`, then how/why does that virtual influence translate into physical influence? * If the government of their community is purely physical, then how/why did they come together to form this physical community (i.e., was a physical meeting of these people taking place when The Event happened)? ]
[Question] [ When you delete data, you make it impossible to retrieve for all times in the future, assuming you have done it right. However, the data still existed in the past. In a world set in the 22nd century, where time travel has been achieved with negative mass tachyons, people can simply go back in time and get the data before it was ever deleted. Similarly, if a credit chip is destroyed, one can simply go back to the time before it was destroyed and get the information off of it. Most people have access to negative mass tachyons if they are middle class or higher. How could a citizen securely delete data and destroy sensitive papers when a criminal could go back in time and get it before it was deleted/destroyed? [Answer] Go back in time, and prevent the data from being created in the first place. If it never existed, it cannot be retrieved. If you wanted to make sure you have a private copy without creating a paradox, then before you travel back in time, make a copy of it, encrypt the crap out of it with a key that only you can know, take it back in time with you to the just before the information is created: As soon as it is created, destroy it, by whatever means necessary. It never gets out, but it was still created (no paradox) and you have that encrypted copy you can hide where only you will find it, and only you know how to decrypt it. When you return to the future, retrieve the data from your hiding place and decrypt it. Thus the information was still created, and still existed the whole time, but you have the one and only copy. If the future was changed by your actions and the information was re-discovered, just repeat the process. Edit: Some comments are concerned about "causality". In any time-travel story, causality is out the window from the start: It is 2022 as I write, and I know a great deal I did not know 50 years ago, in 1972. If I travel, as I am, to 1972, I have broken causality just by existing. The myriad causes that caused me to change in 50 years have not happened. My brain and my knowledge exist without cause in 1972, and anything I know about their future is impossible for me to know. A time travel story must be written, from the start, with a severely liberal take on "causality." The root of the problem is the time travel itself, events from the future (the invention of time travel) have already caused changes in the past: The existence of the time traveler and the knowledge from the future they have, including the certainty of what is about to happen, that nobody else, anywhere, may know. For example, they may lie in wait for Oswald (and any other assassins) and prevent Kennedy's assassination without Kennedy ever suspecting there even was a plan to assassinate him. Precisely how one redefines "causality" in the fiction is up to the imagination of the author, but pretending that the definition of causality is unchanged is particularly unsatisfying, at least in my view. [Answer] The accepted situation (in the right circles, at least) is that if paradoxes exist, time travel is not possible, and if time travel is possible, paradoxes cannot exist. In your case, you've described a paradox -- if you delete data retroactively to its creation, no one can retrieve it by traveling to a time before you deleted it, but if they can prevent you deleting it, they can still retrieve the data. The only way time travel can get around this kind of ["grandfather paradox"](https://en.wikipedia.org/wiki/Temporal_paradox) is if the many-worlds hypothesis is true: you go back in time and change something, but you don't change your own past, you just create a new timeline in which, in this case, the data you deleted never existed. It's still there where/when you came from, but when you return to your origin time, you'll be going up the new line. This gets confusing very, very rapidly -- recommended reading is The Man Who Folded Himself by David Gerrold or All you Zombies and The Door Into Summer by Robert A. Heinlein. [Answer] ## EMP Here’s one fascinatingly ridiculous idea: tachyonic magnetic propagation via an Alcubierre drive. We use a modified Alcubierre drive moving faster than light speed to transport an enclosed space-time field that contains a concerted high-power magnetic pulse backwards through time. The space only has to be as big as the storage device we want to destroy, and stay entangled to the hard drive’s “quantum identity signature” as it travels backwards through time and space. This TSEMP, or Time-space electromagnetic pulse, will magnetically wipe the drive across all instances of time. If you know exactly when the drive was created, stick a reverse timer on the TSMP and you’re good to go. ## Encrypt It That said, there’s no need to destroy it if it is encrypted properly and only you have the key and no one else can get it. Heavily encrypted data is not viewable in a reasonable time frame (until massively parallel quantum computers are a thing, anyway) because, while modern computers can technically crack a well-hashed bit of data, it would take a while, in some cases 200 years or more. ## Caveat Interesting aspect of the ability to travel backwards in time: you could take a computer back far enough in time to make progress decrypting data, then travel back to the future to read it when it’s had many decades to decrypt the hash. Granted, you’d need a computer that can survive that kind of power use for decades AND travel back to a time with power and secure location, but those things can all be hand-waved if we’re traveling back in time to begin with. [Answer] ## Store the data using quantum entanglement. Quantum entanglement has a neat property: entangled data can only be read once, and doing so instantly turns it into random noise. And by instantly I mean literally instantly, not delayed by the speed of light. Anything faster than the speed of light can be seen for some reference frames to be going back in time, so though we can't currently test this without access to time travel, it's not implausible to speculate that reading quantum-entangled data erases it across all of time. This means you're set! Once you retrieve the data in the future, by doing so you erase that data from the past. [Answer] # Remove, Falsify, then Actively Defend the Data: This answer assumes you and the others trying to obtain the data DON'T want to create paradoxes. If paradoxes are okay, I don't think you have a problem. Copy and destroy the data at its creation. Then kill the creator before it was created. That's not very satisfying. Not to mention that the data could still exist in a parallel dimension if you create a paradox. While the ability to time travel is amazing, it doesn't make the traveler god-like. Someone has to go back in time and obtain/observe the data. Find out all you can about the handling of the data, then falsify the records of it to throw off rivals trying to get it. They don't simply get to pluck it from mid-air. If they don't know what the data is first (or even if it exists), they can't know they are being fed false data. So obtain, then delete the data just after it's created. Without causing paradoxes, this will be hard. Defend the creation site/time until you know no other time traveler has the data. Kill rival time travelers if they show up and make sure there is no record of your theft so time travelers don't know why their friends went to steal the data and never returned. Replace the data with fraudulent information so thieves from the future don't know they are being tricked. Now you need to know each time the data was accessed historically. Use the same steps to go, add the data back long enough to allow it to fulfill history, then delete it again. If the data was openly circulated, then the only way is to disrupt the timeline. But if it was a private file, then these steps mean you are present to protect the data when it is exposed but don't need to guard it throughout history to assure no one else has access. [Answer] Welcome to the real world. You don't need to have time travel in order to get the problems you describe. The important thing is, data travels to the future by itself. In order to have particular data secret, you need to guard it from the act of the data creation all the way to the data destruction. A single failure - and the data is copied somewhere and the control is lost. What the time travel brings is that the future may offer a different, more efficient methods of data extraction from encrypted, physically locked or otherwise guarded storage. But this is not a big deal, really. What you have on your side is the technology progress and technology obsolescence. Have you ever tried to read a 2001-made HDD in 2022? A tape from 1978? A punch card? 20 or 40 years passed and it is already hard - even if the media is in quite a good state. A book from 19th century is hard because the language is already not the same. [Answer] # Generate and store the data securely. So long as the data is generated in a place that's inaccessible to others it's much harder to steal. Have facilities that have anti time travel defenses so people can't spy on them or get inside easily. Have guns so if someone time travels outside you can shoot them. This ensures the data is secure. Make all your key data here, and store it here as well. The site will be extensively monitored well before building the facility to ensure no one time travels before the building and digs under it or something. The site will be airgapped, and have lots of heavy steel doors to go through to generate data, of course, along with security measures designed to resist future technology attacks. # Have heavy explosives near all sensitive data. One obvious way the government could get secure data is sending an order into the past repeatedly to send an army to the location to kill everyone and take it. Have a tachyon detector to detect if you're in the main timeline. If you're not, automatically set off the explosives. If you detect a large army, detonate the explosives. This ensures people can't use time travel to access your data. These explosives will be set up well before the facility is made with a particular timeline, to ensure people can't butterfly them away. The longer the better. Over time the facility will get more secure as it will be harder to break the timeline explosives by going back. # To delete the data, delete it. The data is stored in a reliably accessible way only in the main timeline. In other timelines it explodes. If you delete the data in the present there's no easy way to access it. [Answer] Self Healing Paradox Go back in time to the birth of the universe and stir violently using the large scale weapon of your choice. Vanish in a puff of logical conflict, well satisfied that any chance of "your" universe existing is gone. This includes the invention of time travel. [Answer] So a lot of answers here talk about paradoxes and the need to avoid them etc. But that really depends on the rules of time travel in your universe. You could have the act of departing one time and arriving in another become two decoupled events. So if you travel back in time, someone killing you before you travel back in time wouldn't stop you appearing in the past. Now you appearing in the past might then seem like a paradox, but it's no greater paradox than time travel itself. If you accept time travel you have to also accept the ability to influence events before your influencing act takes place. It seems reasonable to me to say removing the initial act of travelling wouldn't undo the change it caused in the previous timeframe. --- Taking all of that means you could travel back in time and prevent the data from being created, so long as your very appearance caused the dataloss (so there's no window of time to stop you). 1. You time travel on top of the father of the person that creates the data, killing them in the process (Harry potter splinching-esque). 2. Nobody can stop you from travelling back, because the events are decoupled. 3. Nobody can usefully prevent you from killing the father, because even moving him out of the way likely means the conditions that led to the creation of his exact same child are lost (different sperm reaches the egg, child has a different life, etc) 4. To be extra certain you could go back a couple more generations and splinch the great-great grandfather instead. Ensuring the ripple effects are so huge that nobody could repair them. This form of time travel also allows you to jump back and forth in the same timeline without much headache, means you can have multiple versions of the time traveller in the same timeline, and avoid the grandfather paradox. I suppose this could be called 'lossy' time travel. Like an MP3, where all the information that leads to a specific output is lost, but the final result is the same (don't @ me hi-fi purists; I know, I know.) [Answer] ## Keep an Access Log If you just go back in time to delete the data you no longer need, then you will keep yourself from being able to use it in the past when you needed it. So instead of deleting it from the whole timeline, you just delete it from most of the timeline. As the name implies, an access log is a file or data table of some sort that you associate with data to keep a record of every time the data was accessed. So, let's say you have a user record that has been accessed 7 times in the past 5 years since it was created, you now know the exact 7 moments in time you need this data to be there. So, using the log file you just delete everything around those 7 moments (including the log record itself), so that way if a time hacker tried to go back in time to access the record, he could not without knowing the exact microsecond that this information will pop in and out of existence... which he can't know because the only place to look that information up is in these 7 microseconds spread out across the 5 years this data existed. This means any random scan of the hard drive in the past would only have a 2.3e13 to 1 chance of having the data on it. Furthermore, while this technology makes data breaches seem more dangerous, they actually make them less dangerous than they are in our world. In our world, hacks and spyware are nearly always identified and addressed eventually, but the damage that is done in the past in immutable. However, in your world, if you ever find malware on your server you not only have the power to delete it, but you can delete the malware from every point in history such that the data was never compromised and hackers who get caught don't just get locked out, but they lose everything they ever gained from thier hack. Not getting caught for now is a lot easier to do as a hacker than not getting caught ever. ## Reality Check > > Most people have access to negative mass tachyons if they are middle class or higher. > > > I find this a very unlikely event at any point in the future no matter how advanced society becomes. Today, nuclear weapons are a nearly 80 year old technology that are disturbingly easy to make with modern manufacturing technologies compared to all the smart phones, nanotechnologies, and other high-end capabilities our society has access to. But the average middle class citizen can not nor will he ever be given the freedom to own nuclear weapons because that is automatic suicide for your entire civilization, and probably the world. The ability to go back in time and edit it, is FAR more dangerous than any nuke. While a nuke can end a civilization, a rando with a gun could go back in time to prevent a civilization from ever being born causing far more damage with far less resources; so, for this setting to make any since, the technology to edit data in the past (pushing around a couple of electrons here and there) has to be distinctly different than being able to actually send a person into the past, and even the ability to manipulate past records would have to be VERY strictly regulated or preventable. If the same technology that a private citizen can use to protect thier privacy could also be used to manipulate the outcome of the 45th presidential election of the United States, then the benefits would outweigh the risk of allowing private ownership, and all time travel would become the exclusive prevue of a small number of superpower governments. So to limit the destructive eventuality of these devices, there would need to be one of 2 solutions. Either: A) An effective means of locking off significant parts of the timeline to time travel... unfortunately, making this whole technology a moot point. Or B) This technology needs to be a closely guarded secrete controlled only by a small handful of individuals to make sure no sociopath ever gets ahold of it and decides to start playing God over billions of people's lives. [Answer] Security. The data is important, so it must be stored on a mainframe disconnected from the internet. Even tax organizations have systems where people have two seperate computers with one connected to the internal servers and one with internet access. So important information is stored on such a disconnected computer or server, and you simply have security. Even if someone travels back in time they still have to deal with said security to get in. If necessary you send someone back with the newest security upgrade tech to improve it every now and then. After all, the information was secure for some time before someone timetraveled right? [Answer] As others have already posted technically this is impossible. The way around it is instead of permanently deleting the data (Which is technically impossible). You permanently protect it. You will have to say that a special machine exists inside of this world (For now we will call it the black box). There can be multiple black boxes. A person enters in the data they want to permanently protect into the black box, including what time the data was first created, the black box essentially runs a program so that it is constantly detecting if anyone touches/accesses/ or sees that data in the past. If someone does the black box jumps back further than that person and does something to keep the data protected. [Answer] ## Limit the time the information exists. The premise that a time traveler can "just go back in time and take it" supposes there's a point in time when the information is easy to steal, and, to a lesser degree, that no one else is trying to do the same thing at the same time. If you know a piece of information is sensitive, you can schedule to have it destroyed quickly. For the short time that it exists, it can be actively guarded against all except authorized time travelers. Anyone who needs to access the information, near-future or otherwise, will need to visit that short window and clear security. [Answer] # Ensure it doesn't come into existence The simplest way to secure your data is to guarantee it doesn't exist in the first place. This answer tries to ensure that it happens. Let us say you need your secured bank statements to do your taxes. We shall assume all data is safe before you ask for it, and the transfer of the data can't reasonably be intercepted. 1. Ask for your data, in whatever way you want. 2. Fill out the tax forms 3. Take the tax forms to a past you, before you asked for the data. 4. Hand over the tax forms, and do not ask for your data. This could ensure your data technically isn't stealable. It does come with its own problems though. ### The way around > > Ever heard of [save scumming](https://tvtropes.org/pmwiki/pmwiki.php/Main/SaveScumming)? It is the act of going back to an older save with new information, you gathered to beat RNG or try for a different outcome. Now, mister X likes to do something similar. He simply tortures people to get the data he wants, knowing he only needs to keep it secret for as long as it takes to obtain the data. Then he copies said data. Afterwards, he brings the data back to just before the point he started the whole operation, erasing the torture timeline while keeping the data. > > > > This breaks any security you might create. Ever. Now try to keep people out of the stock market... [Answer] Police and Lawsuits You said this is a Universe where time travel is easy. I think it goes without saying then that it requires policing, in order to prevent paradoxes like the ones above. This doesn't have to be government policing. A company that specialises in data protection may have as part of their service a kind of temporal enforcement to prevent data from entering the future from the past. Or they may simply bring out a lawsuit against anyone who has managed to gain access to said data and use it to affect the future. The entire question over the legality of accessing data in the past without necessarily having it in the future would become an interesting philosophical discussion inspired by such a world, potentially even a hinge of the plot. ]
[Question] [ Two medieval armies are fighting one another. Their infantries are approximately equal, and their artillery pieces are well matched. During one battle, they enter what appears to be a stalemate. Then one side reveals that they have a trick up their sleeve. A wizard, who has been secretly working for their king, uses the one power he has - giving soldiers the ability to fly. He can cast a spell on only one man at one time. Each one can continue flying for about ten minutes, at which point reality wakes up and the soldiers stop acting like birds and start acting like falling bricks. The exceptions are those that land before it's too late. At the first battle, the other army is so scared that they just turn and flee. But they make up their mind that they will return and fight another day. And so they do. How can the army with flying soldiers change their battle plans such that they can take full advantage of their new powers? In the interest of making this less broad than it seems, I'll narrow down the areas I'm looking for: * Attacking on multiple sides (i.e. the front and back, because the flying soldiers can easily get to the back) or otherwise moving their forces * Attacking from the air, e.g. actual falling bricks * Armor and weapons the flying soldiers could use. And no, the wizard has no other powers. I know, he's a pretty sad wizard. But I want to keep this as simple as possible. Note that it gets increasingly harder for soldiers to fly when more weight is added on. The soldiers may decide to not wear as much armor as they would otherwise - or at all. --- The top speed of the soldiers is about 20 miles per hour, and their top height is about 100 feet. The wizard can cast the spell about once every minute, so the soldiers are effectively staggered. The armies, though are each about 500 strong. Rather large, compared to the number of soldiers that can fly. [Answer] Ok, so, making a couple assumptions here: Assumption 1. The way the spell magic is invoked requires sentience and free will. So no boulders for example, which by this assumption means that otherwise the wizard would himself have to direct such an attack thus defeating the apparent/best application of such a strategy. Assumption 2. All else is equal, battle tactics, attack and defense strategies, strength and stamina of the soldier, all are the same/expected as normal, in other words no other magical or metaphysical interventions. ### Problems --- Given the above the main problems that I see with this capability are: 1. 100 feet, although perhaps at a high inclination to the archer, is within target range for an expert archer. 2. At 20 mph, while faster than most game animals in areas of natural cover, is less than a flat out run for most game animals and still likely within the range of standard training for an expert archer. So it seems that well trained and committed soldiers who are trained as archers would thus have few issue keeping the heat on these flying attackers. 3. Obviously the restrictions on the wizard's ability to perform the spell and the restrictions on the magic prevent a sweeping advantage, so we have to make due with a trickle of soldiers who can fly, which would seem to require a well formed plan which adapts as the number of flyers increases, or which otherwise makes the best use of only a small number of flyers in an otherwise coordinated strategy. These subtleties make such a strategy difficult to form and be ready apply literally over night as the question suggests. ### Suggestions and Responses to Other Answers --- [Answer] I would guess their best use would be in intelligence gathering. Being able to see where the enemy is keeping all their troops and see the ambushes before it's too late. As an attack vector they would be asking to be shot. Arrows are good at poking holes in things and archers like to practice on enemy targets. A flight of 100 arrows would be very hard to dodge, and even one arrow would be hard to avoid, since when it is coming at you it is just a brown dot, and it would be against a shifting background. [Answer] Three major advantages: ### Height Arrows going downwards are far, far more powerful than arrows going up. It would be incredibly difficult to shoot someone out of the sky if they're high enough yet still easy for the flyer to do serious damage with some loaded darts. A taller person has much more advantage than someone shorter. They have a little more strength due to gravity. They can knock people down better. They have a better chance to hit the opponent's head and neck. So a flyer could just be levitating a foot high near ground and still get a significant advantage. It's incredibly similar to how cavalry functions. ### Tactical Flexibility This is huge. Imagine an army that doesn't care about mountains or rivers. We take our bridges for granted. Crossing a river is very dangerous and difficult. They can strike anywhere, take many existing forts by surprise, because most utilize nature as hazards. Walls suddenly become obsolete. Soldiers can fly anywhere into a city and strike its weakest points. Also flanking. A wall of pikemen may make it difficult for someone to charge past them, but a squadron of flyers armed with lances can strike many polearm formations from behind. ### Aerial Bombing They can light up flammable substances like fat and oil and bombard things. They can drop diseased carcasses. This isn't limited to combatants - an aerial squad can easily raze or poison a whole city during a siege. [Answer] All answers so far treat flying infantry as just another unit. Ho hum. I think a wizard who is a one trick pony but a little wily might leverage this for the shock and awe value: like fighting Aztecs using horses and cannons. Strong weapons to be sure, but an opposing force outnumbering the Spaniards 1000 to 1 could storm and overwhelm them - if they understood what the weapons were, their nonmystical nature and their limitations. The key for this wizard is to leverage his trick to maximally scare the other side and crush their morale. For one, ideally the wizard does not reveal his trick up front by having some regular dudes fly over in broad daylight, chuck some rocks and fly back. Insufficiently magnificent. The flying guys should wear wings and disguises (djinni!), come at night and pour flaming liquids on the enemy - or something comparably confusing and outré. The enemies should not be allowed to understand what is really going on. Even if he has given away his trick by sending over the daylight rock chuckers first, he could then mix it up such that it is not clear to the enemy that he really has only 1 trick. Sort of like a play with one actor who wears different costumes and uses different voices. A team of flyers in a dragon costume could fly high above - an omen! A flyer at night could drop something scary into the camp from a great height - where did it come from? Flyers could do weird and unsettling things which would ultimately have more impact than plain attacks. The wizard's own side should not be privy to these doings but should be equally mystified. Finding themselves allied with strong magic will boost their morale just as it crushes that of the enemy. This could be an "Angels of Mons" type thing - <https://en.wikipedia.org/wiki/Angels_of_Mons> [Answer] The Wizard would be better off casting the spell on a man-sized boulder, and then just letting it fall on the other army. [Answer] Make the General himself fly. Being able to see what is happening from the skies and giving orders through waving flags would make your own army's recon much better than the enemies, which would probably turn the tide. If you can only get a handful up in the sky, better make them valuable. The general, who needs as much information as he can to lead effectively, seems like the best choice. Banner carriers might make for a good second option. The morale effect of seeing your kingdom's banner (preferably at ten times the ordinary size) flying over the battlefield would help a lot. [Answer] ## Cut the head off, and the body falls. Send a flying attack squadron over the opposing army to assassinate the enemy commanders, who would normally be completely unreachable otherwise, safe behind their array of soldiers. Ten minutes of flight time at twenty miles an hour means a maximum range of ~3.3 miles. If the enemy generals are not at least this far away removed from the front lines, after having witnessed the wizardry from the previous battle, then they have no one to blame but themselves. [Answer] Cast the spell on your best archers, sans armour. Have them attack from the air. Gravity on your side is a huge advantage when taking other archers, you can get really close to infantry for clear shots, and they`re very mobile at 20mph. They can probably finish the battle by themselves at 10 kills a piece before the spell ends. [Answer] How close to the target must the wizard be in order to cast this ability? Who controls the flight: the target or the wizard? Does the flight spell have to be cast on the soldiers? Can it be cast on animals or inanimate objects? For example, if it can be cast on ballista bolts, they wouldn't be affected by gravity, making the siege weapons considerably more accurate over very long range. It also would make them easier to reload. If he could cast it on the siege engines themselves, moving them quickly or to higher ground would be easier, even if it doesn't completely nullify the weight. The additional speed of the flyers, coupled with the ability to ignore terrain, would make them excellent for sending messages between battalions, especially as knocking out the messenger would be particularly obvious, nullifying the [Two Generals' Problem](http://en.wikipedia.org/wiki/Two_Generals'_Problem). This is especially useful if the wizard doesn't need to be anywhere near the soldier in question or even have line of sight on them, allowing the soldier to be regifted with flight after 10 minutes. Even without sending direct messages, flying semaphore operators could be used to quickly and efficiently manage a large army spread over a battlefield. Is the carrying capacity of the flyer a set threshold of the combined weight of the flyer + load, a set threshold of the load, or is the load relative to the carrying capacity of the flyer? If the stronger the flyer is, the more they can carry, having your largest soldiers with big hammers lead a flying charge — almost as fast as a mounted charge, but with considerable more manoeuvrability — could be devastating, particularly if followed by a more typical mounted charge. [Answer] I would use the flying units as a suicide squad. I would have them carry some sort of flammable liquid and dispense it over enemy troops from above. Even if they are shot down by archers they will fall down and spill this liquid on the field . Now archers from my army can shoot arrows tipped with flame to these areas to spread fire and kill troops. [Answer] Use flight for strategic positioning. IE a Thermopylae esque situation. You have 500 soldiers on each side. Each soldier can fly for ten minutes at twenty mph which means they can travel 3.3 miles and arrive fresh at the fight. In an hour he can transport 50 soldiers 3.3 miles around the enemy and arrive unwinded. [Answer] The first thing to realise is that the other army is returning to fight. What does this mean? Well, you don't fight if you know that the foe is superior, so first, the opposing army will have thought of something that renders the advantage of attacking from the air nearly useless. Second, the commanding person will have convinced his forces that the ability to fly is evil (for the 'spirit' of the army). So, taking that into account, how do you beat the opposing army? Take them unprepared, while making them think that they're taking you unprepared How could this work? One way would be to split your 500 man army into 4 smaller groups. Send a couple of men (archers with bows) into the air towards the army with the appearance of either scouting or for assassination. Give him armour that looks heavy, but it actually relatively light (I'm not concerned with the effectiveness). Once they're spotted, have them flee slightly out of range of the other army, so that they get chased. At a predefined place, split the 2 flyers into 2 separate directions. If the chasing army splits, lead them into separate ambushes (the purpose of slitting the opposing force is to cause a little chaos so that the opposing force no longer acts as a whole, making them easier to beat). The two flyers splitting is actually a signal for 2 of the 4 smaller groups to prepare to attack from the rear while the other 2 groups have set the ambush. If the opposing army doesn't split up at all, lead them back to what appears to be your own army's camp (so that the opposing army thinks your army is vulnerable and attacks, only to find nothing there and be attacked in turn), where another 'scout' is sent up, which is actually a signal for the 4 smaller forces to come together and attack the opposing force from the rear and sides. There are lots of different variations and ideas similar to this, but the general gist is, as always, to play on expectations and use unexpected tactics, such as using someone going up to/coming down from air as a signal, or making someone appear like they're sending a message somewhere, when it is actually a signal to some other part of the army, or just a distraction. This in then used to to take the enemy, who is unprepared for an attack. As soon as the other army expects you to do something, stop doing it. [Answer] Over time, the entire culture would evolve around flyers vs flatlanders - and I imagine defences would evolve as well (think walls covered in pikes). Just as our built environment has been constructed around the average height, weight, vision, reach, etc., you would see aspects of their society evolve in ways we likely cannot predict. I'd say a property like that might even drag them out of the middle ages fast. But given that it's the middle ages, we might see a general slaughter in an attempt to seize the wizard and torture the secret out of him. [Answer] The top height of 100 feet and the slow flying speed makes flying soldiers excellent targets for archers, as others have pointed out. > > How can the army with flying soldiers change their battle plans such that they can take full advantage of their new powers? > > > Easy. You don't use it when they can see it, and you use it for castle sieges or to get a few men, scouts, or assassins behind enemy lines. Given the limitations you have outlined here, on the numbers that can be in the air. The folks on the ground can easily track the ones in the air and be there to meet them when they come down, which will draw forces away from the main event. I would give your flyers lightweight armored discs to deflect arrows, which would be on their feet. Whoever your flyers are, they should be elite and able to cause death and destruction even without armor. Flying archers would be wonderful, in a general battle, but they will need to strike quickly and come back behind their own lines, long before it wears off. [Answer] To expand on the answer by @BM your flying guys would be better suited to scouting the enemy out and relaying orders to your soldiers quickly and efficiently. The main reason why the flying battle idea wouldn't work would probably be the archers. If Army B (the army without the Wizard) is willing to come back to fight these flying people, they are probably not insanely superstitious (else they would not have come back willingly). This means they know your guys are vulnerable to arrows, especially if they strip their armor to make flying easier. I imagine your Army B would simply let loose a few volleys of arrows and problem solved. It takes time for you wizard to make a sizeable number and Army B will not have to face the enemy until the wizard has given the soldiers this ability. Since it only has ten minutes of effect I doubt 1 wizard could get more than a group of 10 soldiers enchanted before the first few started to lose this ability......meaning that they would have to go and individually attack the enemy. [Answer] It would not influence greatly a ranged battle but a siege yes, especially if you keep it secret. You can enter any fortress and open the gates at night. Otherwise I think it's is useless since there is archers to shoot at your flying men. [Answer] Have the flying soldiers harry the enemy from above with their melee weapons while a cavalry attacks simultaneously. It would be difficult for the enemy to defend against a mounted charge while they are also being attacked from above (and potentially all sides) by flying foes. The cavalry would be much more effective against their beleaguered foes. [Answer] As was already mentioned I don't see any practical use for a flying troops in the actual combat. BUT. I see many great uses beside combat. When you have a two armies of equal strength then direct confrontation is something you want to avoid. You want to play smart, get the upper hand and then crush your enemy. Your flying troop could scout a bit. Flying might also proove useful in difficult terrain which might catch your enemy by surprise as you managed to traverse the dificulties much faster than he exected. They could also fly into the enemy camp under the cover of the night and set their supplies to fire. Without supplies their army will starve. And starving army might surrender before any actual combat takes place. [Answer] Since the soldiers can only fly one every minute and only for a limited time they would have little use as a direct attack. I would use the ability to gather a flanking force behind enemy lines by sending the soldiers to secretly fly to a designated spot until there was a large number of them gathered, then they could attack the enemy in force. [Answer] So what you can do is to teach cavalry how to make "flying jump". 1. Cavalry is not only fast but can't be stopped or crippled by regular cavalry stopping methods (Trou de loup or pikeman) 2. Cavalry can use normal terrain to hide well and literally just jump from behind the hill (mountains that would be considered natural wall would be easily overcome) 3. I would not be considered flying but just jumping so the weight issue would not be taken into consideration. They would just move in straight lines. [Answer] The flying could be very useful to an assasin on the battlefield, they could fly up, see where the enemy king of general is, and then use a long distance weapon like a bow or a spear, to eliminate the general. This would de-moralise the enemy side, and could help win the battle. Once the general was dead, another soldier could be sent up with [greek fire](https://en.wikipedia.org/wiki/Greek_fire), an extremely dangerous incendiary flamethrower-like ancient weapon. After the fear and losses of the other side, they would likely desert or just be wiped out. [![Greek fire](https://i.stack.imgur.com/E2fyo.jpg)](https://i.stack.imgur.com/E2fyo.jpg) Greek Fire [Answer] Why even use soldiers? Instead have the mage lift burning pots of oil and precision-strike the center of the enemy formation. This would have a much greater impact than a couple fliers. Besides that, if you must use humans , you'd want to go after the enemy artillery with your best troops, but this is hard to pull off with just 1 guy every minute (10 guys max). You could have them drop flaming oil canisters while flying (panic the enemy horses!). You could use them as a distraction: dress then up like dragons and draw archer fire while the army advances. Maybe train men to be precise archers while flying so they can snipe the enemy general, but that would take a lifetime of practice. Otherwise, just use them for scouting. [Answer] I can see kamikaze attacks could work well for some, or they could just forget arrows and pour boiling oil on the enemy from above - keep a chain of them doing it, and they would do well. It would also be easy to get them at night too - flit down, take out the watchmen from above with silent crossbows and then infiltrate the camp.... [Answer] To simplify things, I'm going to call the wizard's soldiers Soldiers A, and the other soldiers Soldier B. The best advice would be to attack on days when the Sun is bright and shines a lot; this way, when Soldiers A attack from the top, the Soldiers B would be blinded by the light from the sun, which would: * disorientate them, * make their neck/head ache from looking up a lot * make them dizzy, and * disable Soldiers B from targeting Soldiers A using projectiles either because they cannot see Soldiers A or because they are disoriented Despite all these things and many more happening to the other team, Soldiers A will not have any of these side effects if they are concentrating down. Now for this strategy to be most effective, Soldiers A have to attack using ranged weapons from quite a distance from Soldiers B. This would further ensure that it would be near impossible for Soldiers A to even land a blow on the opposing team. [Answer] Either the wizard can levitate himself, or train another wizard to do the spell and levitate this second wizard. The airborne wizard would fly over to the enemy HQ and levitate their leader. ]
[Question] [ In my world, I have a form of magic that can be used by a practitioner to connect with a subject's mind at touch range, and effectively give an experienced, powerful practitioner total control over that person's mind and body. Such a practitioner could easily kill an individual, or - given a minute or so - drive a person insane in any way imaginable. They can read the subject's mind and alter, delete or implant memories. Now, suppose that a practitioner of this art was unsuspected, and they wanted to do something nasty to an oppressor, and they could achieve the physical contact needed for long enough to do whatever they wanted. However, doing something obvious such as killing the oppressor or driving them insane immediately would lead to their being suspected and punished, so something more subtle is in order. How could such a practitioner subtly influence an oppressor's mind in such a way that it was not immediately obvious that something had been done, that would ultimately lead to such an oppressor becoming insane to a point that led to their effective social incapacitation, suicide or becoming such a threat to society that their execution would be desirable. There would need to be several days at an absolute minimum between the practitioner doing their thing and the subject's psychotic break. The psychotic break should not take more than about a year either. As far as possible, use real-world human psychology, though the mind-set of the subjects is more 17th-century and more superstitious. Edit: Assume a single event. The practitioner must gain any information needed from the subject from the same contact event that must be used to cause the delayed insanity. [Answer] Any time you want a subtle influence to have sweeping effects, it should be assumed that the influence is highly personalized. It might be that the practitioner can form such a personal connection during the touch, but more likely the practitioner would spend some time observing and, ideally, interacting with the target. Since the practitioner cannot be there when the insanity breaks out, the target must build their own insanity. The effect of the practitioner would probably be along the lines of an itch that the target scratches harder and harder. The actual source of their insanity would be their own doing. HDE 226868 claims "people on this site are just diabolical." If we seem diabolical, consider Randall Munroe, who on December 12, 2007 actually did drive people insane at a distance, including myself. [His work](http://xkcd.com/356/) is still at large and destroying minds to this day! [Answer] Given a 'one shot' approach to it - you need something that'll escalate. Ideally triggering 'insane' actions and self reinforcing. So lets go with the 'religion' angle - a set of beliefs that are circular and impossible to contradict. Lets go with something Cthuluesque - There is a great evil and it's currently sleeping. * You have been given a message with ultimate authority (God, ultimate good, whatever fits this world). Evil is rising in the world. The only way to prevent evil from rising is through the destruction of innocence. * Destruction of innocence is wrong, but it must be done for the greater good. * "Authority" has been thoroughly subverted. They are agents of the evil who want it to rise. * Plant a positive feedback mechanism. A sense of pleasure when they 'save the world' that's in proportion to how 'effective' they've been. But tie it into their own perceptions of it and how big an inhibition they had originally. * Make them forget the cycle of seasons. Encourage them to believe that the turning of seasons is the sign of the end times. Autumn and Winter are caused because the big Evil hasn't been placated. (This gives you your timeline of about a year, and for bonus points - if they don't self destruct before spring, they'll go quite for a bit and you start over again next year) In doing so, you create a balanced set of beliefs - that doing something repugnant is necessary. Their own morality will stop them from doing it initially. However, because you're rewarding their behaviour, you'll create an addiction cycle - the more atrocious their crime, the better the reward. However, overcoming inhibitions is a sliding scale - the first time you do something naughty feels much worse than the 50th time. So - you may find they hold off for a time, because of that initial state of morality. Sooner or later though, they'll do something accidentally (y'know, maybe tell a child that Santa isn't real) and find that they like it. But second time they do it, it's not as bad, so it's not as much of a thrill. You might also add in some randomish paranoid beliefs, so as to create further escalation/paranoia, such as: * beards are a sign that someone is possessed. They cannot be trusted - they're trying to stop you. * Blue eyes are a sign that someone's a messenger of the forces of good. You should heed their words, they're trying to guide you. Again, both these normally might just be a little odd, but they should serve to further reinforce the fantasy. [Answer] Add a very strong phobia against something which is not in the vicinity of the target at the moment. It can be an animal, an object, or something which will be sent to the target in a few days after you left. Even more diabolical, add that phobia against a family member or very close associate who is not present and will only arrive a few days/weeks later, this is bound to make the target look at least paranoid and hinder him even if it doesn't make him outright insane. The phobia can also be against an astronomical event (an eclipse, for example) which is bound to happen in the near future. [Answer] Why not take an Inception like route? Simply implant the deep suspicion, that grows into conviction, that the target is in a dream and needs to die, harm others, sing naked from the rooftops, or whatever in order to wake up. To have such a suspicion grow, for it needs to begin very subtly and increment in the smallest of ways, associate common events with the idea "this is a dream". This can be interaction with known companions, frequent cultural sayings, even images associated with an upcoming season (like snow in winter). But especially with any attempt to convince the target they are not dreaming, this will tend to greatly accelerate the effect once the target begins to voice their suspicion. [Answer] If the practitioner can choose a time when the victim will be on a trip (and hence away from his family for an extended period), he could induce the [Capgras delusion](http://en.wikipedia.org/wiki/Capgras_delusion) in regard to the victim's family members. Upon returning home, he would believe that they had all been replaced by impostors. Perhaps he also 'knows', upon 'realizing' they are impostors, that the 'government' (or some other entity with power) is responsible for replacing them. When the victim then tries to fight the powerful entity to get his family back, it results in his undoing. This also has the side effect of causing him to distrust those who would be his strongest support system in dealing with the loss of his sanity. [Answer] ## Political suicide An appropriate way to deal with such an enemy would be to have them do publicly something that's completely unacceptable to the society and be appropriately punished for that. Denounce the dominant religion? Claim that the ruler is an imposter and reveal "the true king"? Confess to rituals or sexual acts or any other local taboo topics that have a death penalty at the society? The best option depends on the surrounding environment, but a superstitious 17th century society would offer plenty of interesting options. Simply supress their memories that this is forbidden, and implant a plan to make a public speech on a major event (or write and distribute a pamphlet) praising the taboo practice and confessing their "habits". ## Let them be a part of a conspiracy If you can plant memories, you can make the target convinced that certain powerful figures are allies in a larger plot that has a reasonable chance to succeed; and that a plan has already been agreed upon, with a condition that the conspirators pretend that they don't know each other. The end result, naturally, would be the target doing "his part" in the plot, disclosing himself to the public in the process, and failing to receive any support from the high-ranking "allies" - instead, being arrested and executed by them. [Answer] You could consider the notion of hypnotically-planted triggers, as in The Manchurian Candidate or (with a timescale too short to be useful) stage hypnotism. I have no idea how realistic these are, but you posit total control over the mind. So I would think that could plausibly include the ability to plant some kind of subconscious suggestion or repressed memory, that would re-emerge at a future trigger and cause whatever form of mental change you need. The trigger, then, needn't be something delivered directly by the perpetrator, it could be whatever likely future event you want. Or for another way of doing things: you say "insane in any way imaginable". I can imagine a form of insanity that consists of "act completely normally for 6 months and then enter a murderous rage". So inflict that. Whether these implanted doohickys could be detected by another powerful practitioner of the same magic is up to you, I expect. More concretely, I believe that PTSD can initially show little or no symptoms (at any rate, none beyond those of the traumatic experience(s)), but get worse over time. So: hallucinatory or false-memory trauma, implant PTSD. The victim could be afflicted with intermittent flashbacks, anxiety attacks, and other PTSD symptoms, that likely won't manifest immediately simply because they're intermittent. They'll get worse over time. If your magic allows placing an additional short-term inability to remember the hallucinatory trauma at all, then symptoms could plausibly be guaranteed not to occur until that starts to wear off. Not that real-life PTSD is inevitably fatal or incapacitating, of course, but a bad case of it in a society that doesn't understand it is hardly safe. For a somewhat cheesy example: if you can place a powerful and specific delusion, then something like "you have a lovely balcony in your bedroom on which you like to sit and watch the sunrise" could cause someone to fling themselves out of their window to their death the next time they're awake early enough. They probably wouldn't show any signs that anything was wrong, then again, there's a "risk" they'll mention the balcony by chance to someone who knows it doesn't exist and acts to protect them from the delusion, so that plan isn't guaranteed to succeed. Other delusions are available: "you're an excellent duelist", "you have developed a resistance to cyanide", "anyone dressed as Santa is a demon and should be killed on sight" (implanted in June). Go wild. [Answer] It can be done incrementally. If you can alter people's memories at your whim, then you essentially have control over their sanity. You say that the practitioner can alter, add, or delete memories, so I will give an example for each. You'll see a pattern. Alter memories of decreasing triviality. Start with memories that aren't likely to be accessed regularly, such as the name of a childhood acquaintance. It'd be best if there were multiple memories involving the changed object, as this will cause an internal discord. Slowly, the target will start to feel as if they're getting forgetful, or that their mind is overworked. As this mental fatigue grows, the memories that are altered can become increasingly more important to the target. The goal is to drive the person to insanity by making them doubt their own mind and eventually their perception of reality. Remove memories, first randomly, then focus on specifics. The first memories removed can be randomly selected, but they also shouldn't have a major impact on the target's life. They'll forget things like who they ate with yesterday, people's names, maybe appointments. As time goes on more memories can be removed during each interaction. The target will start to believe they're having general memory issues, with no reason to associate the issues with the practitioner. Once they sufficiently doubt their memory, you can remove specific areas of memory (such as their professional skills, or a family member). Add memories that increasingly conflict with reality. This will run similar to the altering their memories tact. The difference is that they'll have multiple memories of the same event, or remember different events that would be occurring at the same time. Alternatively, you can build up a severe paranoia/phobia, by slowly adding memories of being traumatized by something. A childhood fear of the dark could be expanded upon. After every visit they have a new memory of something frightening or terrible happening during in the dark. As their mind processes these memories, their phobia grows until they start avoiding the dark. This phobia, using the mind's own power against itself, could naturally lead to hallucinations and severe anxiety. (Hearing sounds in dark and being terrified. Thinking you see shadows in the corners of your eyes.) Update: Since the practitioner will only have a single opportunity to affect the target, I would suggest a few alternatives to those above. Completely alter all memories of specific people to be about other people. This is Goodkind-inspired, a sort of reverse Chainfire "spell". Everyone else will remember events how they actually happened, but the target will remember them as if they happened with somebody else. A good friend could be completely replaced by a number of other individuals. As more events are discussed with others, the more the discontinuity will show. Once the target runs into a person they've "forgotten", the cracks in the psyche will expand. The key is to not just remove the memories of the people. The target should be able to argue "No, Bob wasn't there, it was Tom." One completely imaginary person should be woven throughout all of these altered memories. Like a fake childhood friend that has always been in the target's life. Once the target starts insisting, "Just ask Charlie, he was there, he can explain all of this," then people will really start to think he's crazy. Eventually, they'll convince him of it. Add/remove/change a large number of memories to create acute phobias. Change even childhood memories. If there was an incident where they were afraid, but a parent or friend soothed their fear, remove the memory of that soothing and replace it with continued fear. Phobias are irrational fears, so the planted memories will need to make that fear seem rational. They could remember the thing frightening them, or remember other people talking about how the thing "got" someone else. Injuries they've have can be remember as being caused by the thing. I'd use a "timeline" like this: Child-like fears reinforced during young childhood memories. Older child memories have the child-like fears go away, but that lingering doubt is reinforced. As the person "ages", the memories increasingly convince him that the fear is rational. In adulthood, the most recent traumatic memories are altered to be caused by the fear. In recent memory, events that couldn't have really happened are added (somewhat like hallucinations) to make it feel as if the fear is growing in power. The severe phobia(s) will present themselves readily. Anytime something negative happens, their mind will process it subconsciously with these new memories. Their fundamental worldview has changed, and they won't have any way to tell that those fears are unfounded. Severe phobias can cripple people, or leave them confined to their home. [Answer] Give them one of the weird syndromes, like inability to recognize oneself in a mirror, the belief that [one is dead and rotting](http://health.howstuffworks.com/mental-health/mental-disorders/what-is-cotards-syndrome.htm), the belief that everyone has been replaced with imposters, wait, no, it's actually the same person in [disguise](http://www.ncbi.nlm.nih.gov/pubmed/7893241). Choosing the right one with the right trigger might cause them not to show symptoms for days or the symptoms aren't detected immediately. It also goes towards the victims personality: some people would immediately start questioning the impostors, others might wait to see why they're dressing up like their mother and father. [Answer] I can be a simple as letting the target believe he is being stalked by giving him the illusion that "someone is watching him" add a pinch of sometimes seeing things out of the corner of his eye and let it stew on a low flame. This can turn into extreme paranoia until he locks himself in a tinfoil-lined closet. [Answer] Inhibit the body's production of [calcineurin](http://en.wikipedia.org/wiki/Calcineurin). This should, over time, produce schizophrenia-like symptoms perhaps including reduction in working memory, social withdrawal, impaired attentional function, and/or hyperactivity. (This has only been [tested in mice](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC166425/) and not in people for obvious reasons). [Answer] Give them memories of a deep, lasting love affair with someone who doesn't exist. In the memories, that person is conveniently absent for the next few days. Later, when the loved one don't return, the victim seeks to find them. No one, friends, police, etc. know what they're talking about. Do this right, and anyone would crack. [Answer] One approach I came up with was to establish a Dissociative Identity Disorder (DID, also known as Multiple Personality Disorder), with a secondary personality that is aware of the thoughts and actions of the primary personality, but the primary personality is not aware of the secondary personality's thoughts and actions unless the secondary personality wants them to be known. The secondary personality would be established to hate the primary personality and many (but not all) of the people close to the primary personality, and to like the practitioner, some of the people close to the primary personality, and some of the primary personality's enemies. The secondary personality would also be established to be patient, to want to keep its existence a secret, to have little sense of self-preservation of the now-shared body and to disregard physical pain, and with a secondary goal to aid and/or protect the people it likes, as well as punishing the people it dislikes for as long as possible. Since the secondary personality would want to protect the practitioner, amongst others, but would want to punish the primary personality more, it could easily be persuaded to stay inactive for a period and then slowly ramp up its activities over the course of days or weeks. [Answer] Give the target a compulsion to write a diary and keep it in a conspicuous place. Then have them erase their own memory of, and firmly disbelieve any of the events that they have written in the diary has happened the way they wrote it. [Answer] Simply implant the idea in the oppressor that he is God especially if your world has a monotheistic belief system. It won't matter if this drives the oppressor insane, everybody else will think said oppressor has gone absolutely crazy. When everyone else thinks you're insane, soon the oppressor will fit the role to a T. My other suggestion was to totally remove all risk aversion. Sooner or later the oppressor will something sufficiently dangerous to kill himself. The oppressor would become so dangerous to everyone around him they'd think he'd gone nuts. [Answer] I'd go with something like an involuntary tick whenever a particular stimuli is encountered. Like, in Agents of S.H.I.E.L.D., there was the whole bit where, whenever Coulson heard the word "Tahiti," he'd respond, "It's a magical place." Eventually, he realized he wasn't saying "It's a magical place" voluntarily. You could have it so whenever the person being driven insane is presented a particular stimuli, he has to say or do something. The word, "up" could cause him to hop in place three times, for example. A knock on a door would cause him to bark like a dog the same number of times. Three knocks, three barks. And these ticks could be set up so they didn't start to manifest right away. After three days, the first one manifests. After three more days, the second tick manifests. Every three days, a new tick emerges, but none of them go away. Eventually, the poor man is turning in a circle whenever he sees a clock, doing a jig when he hears a pigeon cooing, and reciting the entire national anthem every time somebody tips their hat to him. At 30 days, he'd have 10 ticks, at 60 he'd have 20, and so on, until, after a year, he'd have over a hundred of them (provided a year is the same length of time as it is in the real world.) He wouldn't be able to accomplish anything, and his sanity would be falling apart as he couldn't control himself. Or he could just have increasingly worse nightmares that start to bleed into his waking hours with each passing day until he can't distinguish fantasy from reality. [Answer] Wait for a cloudy day and make them believe the sun will kill them if they are exposed to it for more than 45 seconds. Make the person believe that water is poison. Blood is the only thing they can drink to sate their thirst. Make them believe that yes means no, no means yes, hello means "run away or I'll kill you". Give them a crippling addiction to the strongest readily available hallucinogen ic drug of the time. Make them believe their tolerance is much higher than it actually is. If you wanted them to put on a show as they died you could do the water thing but make them believe only alcohol was safe to drink. ]
[Question] [ As previously stated, I am constructing a world that has a day lasting nine years. The inhabitants must always be on the move in order to avoid the freezing wastelands of the night, but not so fast as to enter the scorched noon zone. Most of the people live on the Dusk side, where they evolved. Others have discovered the poles and set up permanent cities, the closest analogs to Earths. Some have even circumnavigated the latitudes to end up at the dawn side. I am more concerned with the nomadic people. Historically civilization started in the river valleys, where is was easier to set up shop and farm; rather than migrate, hunt or gather. These civilizations would become the empires that lead the way to our modern nations millennia later. But this world would lack that spark. Imagine that humans live on this world, how does civilization come to be? [Answer] The earliest civilizations started in great river valleys, like Sumer (Mesopotamia), Egypt (Nile), China (Yangtze) and India (Ganges). This was because the land near the rivers was easy to irrigate and became fertile for crops. People settled down and abandoned the hunter-gatherer culture when they started to harvest crops. This is called the agricultural revolution and it was the beginning point of civilization. This is how our civilizations started - they key points is that we settled down because we could produce more food from irrigating the land and harvesting crops than we could from our old hunter-gathering methods. So if you want to have a civilization that begins without the settling down part, you need to have a way of harvesting lots of food without the need for irrigating land and growing crops. As others have mentioned, animals can move from place to place, but meat is intrinsically more difficult to harvest with a potentially lower yield (consider wheat takes 6-9 months before it is ready to harvest, whereas animals take several years before they are ready for killing). My solution is to have something like wheat but mixed with something like this plant: [![enter image description here](https://i.stack.imgur.com/vdq3V.jpg)](https://i.stack.imgur.com/vdq3V.jpg) My thinking is that if you want your civilization to start off on the move, then have them cultivating and harvesting plants that will naturally move with them. Tumbleweeds are one of the best examples of plants that move from place to place, and if they were easily cultivated they might give rise to civilizations that moved with them. These tumbleweed/wheat plants could be moving slowly across your world, carried by the dusk and morning winds - and as such they could be the only vegetation that can survive all year around (I am assuming night time is too cold & day time is too hot). [Answer] Your inhabitants could be following big herds of animals, migrating in the same way they do. If the animals are big, you basically have familiar clans joining to hunt them. Soon, they snatch a few baby animals (perhaps after watching for several "awake cycles" which mother is less aggresive) and tame them. This requires time and patience, but with more people forming a tribe it is possible. The result: beasts of burden. If they are in the move, they need wheels and carts soon to carry more than a single person can (they could develop sledges, too). Perhaps they follow the path of the big herds because they make the terrain flatter and the manure can be used for many things (they could even eat some things they can't digest themselves unless they have suffered the stomach acids of the herd animals). People riding carts and wagons can use their time for developing more complex things like the loom. Perhaps they could use the herds for everything: their bones and teeth in substitution of strong metals they can't harvest. With all those things, you only need a surplus of food to get tribe leaders, priests and artisans, the start of civilization. I don't know how they could get that surplus, though. [Answer] In caves, protected from sun and cold. Possibly carved out by a meltwater river during the days. A couple of days, a generation, to learn how to live without moving and time to expand the cave system into something more suited to habitation. Maybe they got lucky and found metals and coal in the cave. It would have to happen many times, rumours that it was possible to survive the day in a cave if you were too injured to outrun the dawn. A story that someone once survived the night in a cave with a hot spring. Tribes in dire need of a safe place forced to take the risk. Some live, some die, one thrives. [Answer] It would be a really long circuit in this case but a lot of the ancient hunter-gather/herding nomads used to follow an "annual round" of the same sites at the same stage of the season year on year. This creates a reasonably reliable, stable resource budget for the group allowing for some leisure at certain stages of the trip around so that they can work on non-essentials, the trappings of a "material culture" that we would start to recognise. This only really works when there is a level of dependable resource repetition i.e. what was here last year, yesterday in this case, is there again this year. Many herding cultures move/moved with their animals constantly but have/had very advanced material culture and reasonable levels of technology up to and including the working of Iron so there is a precedent. [Answer] Several people have commented on how food surplus is the key factor. Let's take this a step further and say that specialists are what you need for civilization (smiths, philosophers, artists, potters). That is, you need enough surplus food that you can afford to have people not busy in food production, be it farming or herding. So to solve your problem you can either make herding more productive (fast growing animals; plants explode into bloom when the "good zone" passes over them), or posit that local flora, including wheat analogues, are clever enough to drop seeds which then wait for the next cycle. You can have time-lapse farming, though your timing has to be good to end up with your own fields the next year. (Plenty of opportunity for conflict there, mind) Failing that, you can have civilized ideas, techniques and goods spread from the poles. You have a rough mapping of latitude to civilization level, where extreme North/South tribes are pretty civilized, but equatorial tribes are howling savages. Makes for good quest fodder -- "You must travel through the wild lands to the opposite pole to retrieve the Holy MacGuffin" [Answer] Migratory people will start off as hunter/harvester, like we did on Earth. But... On Earth we had the issue of gathering enough food, and as Jimmery pointed out, rivers were an excellent answer to the need of harvesting enough food. But your people live in perpetual motion around the globe to chase the light zone. Same will do also plants and animals. In particular the plants will tune their life cycle to the day/night, so that they grow fruits and produce seed during the day. If you set the migration speed to the proper value, you can be sure to always reach a place where ripe fruits are present and you don't need to worry about harvesting in scarcity. Over generation you can even build up memories of best locations, and plan the migration accordingly. Now, with such a bonanza, why would you need "civilization"? Just migrate, harvest, eat, sleep, repeat. And mate in between. [Answer] Other answers suggested mobile plants, like the "tumblewheat". This would work especially well on the dusk side due to the wind, which conveniently is where people initially evolved. Said wind would probably be constant and very strong, from the night side to the day side. On the day side, air is heated, creating a low pressure zone. The cold, high pressure air of the night side rushes in, creating the wind. Night air is renewed by opposite winds at high altitude from day to night side, creating a giant convection cell. (This is assuming that air doesn't freeze on the night side, which would slightly complicate things.) Dusk wind would help plants and animals to move with it, and humans could tap it for movement as well. They could use wind-propelled animals and sailing crafts. This also means that dusk would extend further toward day with the cold wind compensating the hot ground. The temperature difference, which may be considerable at reasonable depth in some places, could be used by fast-growing plants in addition to sunlight. Those plants would probably have a seed or dormant state that can survive extreme heat and cold, with an explosive growth at dusk, and possibly dawn. They could be harvested by the migrants, and even cultivated by planting the seeds for the next passage. This may give them the necessary surplus for developing a civilisation. If they use fast-growing plants, it will have major impacts on their worldviews. Expect them to be long-term planners. Polar cities could use those constant winds for industry with windmills, and even for observation with semi-permanent crewed kites. Migrants could also use lighter versions of those, but they would have to be either mobile, fast-disassembled or fast to build for one-time-use. For polar cities to be viable, axial tilt is probably very small, and even then they may have inactive periods when people lock themselves up to escape the near-unbearable heat and cold. Dawn dwellers may have a harder time, as wind is on the wrong side. If advanced enough, or if animals or plants evolved it, they can use tacking to sail in the right direction. The existence of dawn dwellers may have serious impact to the dusk civilisations, as they could both help fast-growing plants agriculture and hinder it by feeding on them without replanting. This could destroy a dusk civilisation, but also the foolish dawn dwellers as there will be nothing to eat on the next passage. Being migrants doesn't prevent them to build permanent structures, though. The most obvious ones are roads, flattening the ground so the next passage is easier. Reshaping the ground for easing agriculture or herding is also a possibility, as well as ground foundations, even walls and other erect structures that would only have to be minimally completed with temporary materials for usable buildings. Again, dawn dwellers could have an impact. Maybe this is even why dawn was settled, to help dusk civilisations for agriculture and to build faster per cycle. [Answer] You're conflating "civilisation" and "buildings". The two aren't necessarily connected. Most obviously, Genghiz Khan came from a tribe of nomadic herdsmen, and managed to construct a continent-wide empire. Not only that, his empire was governed by rule of law in a way which other European countries of the time were conspicuously lacking. "Civilisation" simply requires philosophy, debate, a way to record the results, and a formal system of norms by which citizens are expected to live. The main thing agriculture provided was population density. It's much easier for farmers to live together in large groups than hunters, and the more people you've got, the better the discussions are going to be. It's not the only solution to this problem though - fishing is another popular way to feed your population, for instance. Or as with nomadic tribes on the Steppes, or Europeans practising transhumance, you can domesticate livestock and move with them to new grazing sites. There are plenty of options which don't need agriculture. [Answer] Another point that you haven't taken in account is vegetation, which would need to find a way to survive scorching summers during 4.5 years and extremely low temperatures during the other side, which would make any form of vegetation and animal life extremely scarce and limited to extremophile single-celled organisms, any form of plant and animal evolution would either have to happen deep underwater, or, as you said, to exist in the poles, where there is a stable temperature year-round (not accounting for the axial tilt, which could cause some problems depending on its angle) Most of the scenarios that deal with intelligent life that always must be in the dusk/dawn to avoid being fried/frozen exist in planets tidally locked to their star, this way, there is a ring where the temperature is constant throughout a 'very long time' and life can evolve as it normally would, but in your scenario i find that the only form of plant life that could survive year round is some sort of fast growing shrub, fungi or grass that spreads quickly, but if there is any continental separation that could be another problem, as the plant wouldn't be able to spread from one side to the other, that brings us back again, making so that any form of life would need to develop deep underwater, where temperatures would be constant during summer and winter due to the thermal protection given by water. But, as explored by our other reviewers, human civilization arose from the fact that we went from nomadism to sedentarism, our modern civilization only exists due to the fact that we stopped moving, so for a large civilization to arise in such a planet, discarding the effects of its particular day cycle, they would either have to find some way to survive on the poles, find a form to survive deep underground for years until dawn/dusk comes (which is highly unlikely) or only exist in large nomadic tribes which developed a more efficient method of organization to make sure the tribe is well fed and alive and always in the move, but you already specified that that is about how they live. [Answer] Writing seems to have been developed, far as I can see, by traders. Travelers, moving from place to place to buy and sell things - including non-physical things like skills and techniques and training and news... and trainees, skilled artisans, marriage partners, and slaves who bore those in their heads and spread those knowledges. So writing and numeracy, which I'd say is ultimately core to any civilization, can be created by people who need to travel constantly. If you're moving, you need to keep track of things. Quantities of things. You want to make a living profit, so you need to keep track of prices and how much you have of stuff, and where you sold things, and what you earned, and also metadata like "butter up the headman of this area for better profits", and "this guy owes us for last time". Note that this is for people moving relative to other people, but I think in a continuously-migratory people, that would be quite common: they wouldn't clump together so fiercely, since they already have the means to move back and forth. Most stories of this type tend to have a "habitable layer", between the melting day side and the frozen night side, essentially making civilization one-dimensional: each tribe or culture rules a stretch of the habitable zone. You can also slice it the other way, into subcultures that handle the different heats - seeder specialists plant the crops on the leading edge, harvesters take the trailing edge, and trade happens between the two. Winds would constantly flow from night to day. The day-to-night edge would have different culture and harvesting approaches to the night-to-day edge. In one, the harvesters would forever be in the chill twilight, harvesting tumblewheat that rolls towards them with the wind; in the other they would forever be retreating from the baking sun, chasing the tumblewheat. They may not even be needed, as the tumblewheat will roll back towards the seeders on its own. [Answer] Tumblewheat and plant life with seeds that can survive long hibernations are excellent ideas to begin with. The prevailing winds due to the convection cell inspired me to consider travel by wind power. What if someone had the brilliant idea to create a hot air balloon equivalent, and then build large mobile platforms suspended beneath them? Parts of the platforms could be covered in fertile soil for farming which would produce high yields due to the "explosively blooming" nature of the dormant seedpod plant life which would now always exist in the habitable zone. The platforms themselves could be steered by sails and slowed down if necessary by stone anchors since gathering metals would be nearly impossible without finding some kind of deposit on the surface. The balloons could be powered by some form of natural gas that rises from cracks in the planet's surface. The people should have mapped out these "wells" of natural gas and steer their platforms from well to well similar to caravans traveling between oasis' in the desert. This could introduce some interesting conflicts when a well dries up, or a new, more advantageously positioned one opens. [Answer] ## Orbital Mechanics: In 2 body systems, bodies tend towards rotation rates that match the period of orbit because of the way that their respective potentials are shaped. We call this [tidal locking](https://en.wikipedia.org/wiki/Tidal_locking). Because stars are much bigger than planets, the planet's rotation slows (usually). What that means for your world is twofold: such a system may not be in equilibrium, and the planet may shortly become locked: dayside and night side forever. If you don't want that, I recommend a very large planet and moon(s), or a somewhat close-by planet whose orbit has a curious integer relationship with 9-years world. The second thing to consider is that the planet (especially one without a moon and maybe smaller) was not always so long-dayed. Civilization could have emerged in an earlier time and continued through the planetary changes that led to 9 year days. ## Within the premise of your question: Civilization requires a surplus of calories. Humans first got this by cooking our food, and second by agriculture. Either could happen and be explained relatively easily. There is an abundance of game while chasing dawn/dusk (and with the advent of cooking/food preservation, more calories) and the denizens could leapfrog: plant at dawn, wait for crop, harvest, move on to dawn (or plant in the evening, wait for dusk and harvest in the twilight of the evening before moving back into the heat of the day). The next requirement is tools which either need to be made in camp, or in bases which the populace moves from and to at intervals as they chase the dawn or dusk. A mobile populace actually has an easier time with this because they will see a planet's worth of geology in their migration, and can set up shop near to mineral resources. No group thrives without specialization - the genesis of trading. Since there are people on the poles in perpetual twilight, it's possible that both civilizations cannot survive without each other - the polar people need something they can't get from the poles (a type of food, salt, tools, metals, etc...) and that the nomads can't get in their travels (food, salt, technology that's only really possible for people who can stay in one place, etc...). Civilizations needn't develop independently - mutual benefit is the basis of civilization, and you have set up 3 very clear societies which could benefit greatly from trade, and who might never thrive without it. [Answer] I got kinda inspired by many answers here, particularly the Jimmery and L.Dutch's. A note I will quickly state that there is a strong question 'how do we define civilisation' here. The process of progress in life of humanity started long before homo sapiens was born, not to mention starting agriculture. It started when homo habilis made his first tool. It started even earlier, when whichever homo it was (cant recall) organized his fellows for a first time with speech. I will try to keep to the spirit of Your question the best I can, but please keep this general thought in mind. 1. In my head, some nomads caught on the idea that if they do some field work on the area in which they are at a given moment, on the next year when they pass on that same area it will have more food for them. 2. More food is good, so they slowly started to get rid of plants they don't need, planting the seeds of the plants they like, building some protection against the elements for them. This lead to some minor improvement for them, so the next thing they needed was to always return to the gardens they set up along the way. This forced them to develop geography and navigation, so astronomy, mathematics and eventually writing system for those. Btw their life was harsh and difficult, so I expect codified laws rose pretty quickly and independently in many tribes. 3. Many tribes = many conflicts. Conflicts over naturally rich in food valleys, best hunting spots, rivers richest in fish. Warfare was, historically, the best motor for human development, and probably so it was here. Weapons is one thing, but organisation is another - discipline and communication are a difference between life and death in war. So the conflicts were another motor that driven the development of mobile civilisations. 4. Conflicts and gardens cultivated along the way brought another point. If i cultivated this garden last year, I want to eat from it now. If someone gets to it before me and plunders it's richers, I'm going to be angry. VERY angry. I'm going to build a fortifications around it and next year I'm going to sent in front of me a quick, mobile force with temporary sun and heat shielding so that i am sure that this force gets to the fortress and the garden FIRST and protects it until my main caravan gets there. 5. One of the great questions with this world which pops into my mind is oceans. It's impossible to travel around the earth only on foot. Maybe continents on Your planet are places in such a way that this is possible - but if there are any choke points, I would use them to block the passage for those I don't like for as long as I can, so that they die in the nightwinter behind me - again I would need a mobile force which can hold as long as its possible and then very quickly rejoin the caravan. 6. The oceans bring another point. The first one to master sailing across them gets an enormous strategical advantage. Building ocean worthy ships quickly is tricky, but may be possible - starting with just traveling along the coast maybe (because, You know, big bad tribe is blocking the land passage out of spite), but in the end creating design of vessel which can be built quickly each year, either in great numbers or great scale (massive raft-island?) and is ocean capable. 7. Far into the future, I see Your species advancing technologically to the point they may even have steam or nuclear powered walking cities - still travelling around the planets after millenia, tough perhaps needlessly at this point. But old habits die hard, we, on earth, still keep traditions which have been rendered obsolete generations ago. On the other hand Poles? Subpolar regions? I don't think I need to elaborate, with right geography they could provide a very interesting alternative avenue for travelling all year round. [Answer] Just like on earth. You migrate to far and in such number that you end in Rome or conquering a almost all Asia and part of Europe. Another thing is how you define civilisation. Remember that the nomadic Jews created a whole book about the magic things that happen when you travel. The rules that are written in there are used to this day. [Answer] Perhaps the civilization didn't actually evolve on that planet to begin with. You could maybe be dealing with a shipwrecked civilization that has had to adapt to this environment. It's kind of a bit of a trope but it does allow you to hand-wave away the need for the civilization to develop over time. [Answer] Perhaps the planet wasn't always this way. Perhaps the days are only 9 years long now but in the past they were much much shorter. A 9 year long day would require that the planet is almost tidally locked with its star (but not quite) as it would need to slowly rotate in opposition to its orbit. This would be a peculiar orbit so it's interesting to think about how that might have happened. One possibility is that a large rogue gas giant planet passed through the solar system and disrupted the orbit and rotation. Another idea is that some disruption, such as the rogue gas giant, moved a small rocky planetoid into an orbit around the planet such that it slowed the planet down. Another idea is that perhaps the planet was originally in a pole oriented orbit with one pole tidally locked. The civilization could have thrived in the thin strip between the dark and light side. Then at some point a cataclysmic shift occurred (again because of external gravitational forces or even an impact) that shifted the entire orientation of the planet. ]
[Question] [ A coven is a group of witches that have come together for a single purpose: apotheosis. This is a divine state of being in which a person becomes an idealized version of their own vision of perfection. This is done through a ritual that requires a circle of 9: eight witches and one sacrificial victim. It is performed over 12 hours, in which runes are carved into the victim's skin. Incantations activate the runes, cooking the victim from the inside as their aether (life energy) is extracted. The aether is absorbed by the witches while leaving the sacrifice a desiccated husk. A witches own magic increases as they absorb life energy of victims. Their physical form also changes to reflect their inner self, making every transformation unique, as well as their abilities. After many years, they reach their apotheosis and transform into their new body. This godlike being is far more powerful than regular humans, and is biologically immortal. Witches can achieve this state sooner or later than others, depending on when they joined the coven and how powerful they were at the start. As things are, a witch who has achieved this ultimate state has no use for the coven. They could easily kill the other witches, or simply leave to pursue their own plans. Alternatively, a witch could kill another member who they felt have gotten too powerful. How can I preserve the cooperation of coven and prevent the inevitable backstabbing and treachery so that all the witches can achieve their goal? [Answer] After decades (centuries?) of backstabbing treachery and murder, a new extremely powerful witch joined the coven. She was so powerful that after a single ritual she achieved apotheosis. (Rumors have it she may have been the last member of a coven back in the Old Country, but there are no survivors from that coven who could confirm this...it's known to have the bloodiest history of treachery of any coven in any country, ever.) This new witch, who is known simply as The Witch Mother, immediately killed three other witches on achieving apotheosis—and it was clear from the evidence found on the corpses that all three had plotted together to betray the remainder of the coven. They were defeated by the variable factor of The Witch Mother joining the coven, as they considered her only a novice and discounted her from their plans. Now The Witch Mother keeps ties with the coven for mysterious reasons of her own, and she doesn't tolerate backstabbing treachery. If you achieve apotheosis through her coven, you had better follow her rules—no killing other witches—or she will hunt you down and kill you herself, and absorb your life essence to further increase her own powers. Or she may use you as the next sacrificial victim for the ritual. [Answer] # Love and Friendship. Why do families stay together for life? Out of familial love, and this is true even if they are not genetically related (adopted children, plus spouses are not genetically related). Witches can be evil to non-witches, treating them as we treat cattle or swine or chickens or deer or elk: They treat non-witches as a separate and lesser species that the witches exploit for their own ends. But, just like hunters don't kill their brothers and sisters as readily as they kill their prey, witches treat other witches with respect and a kind of sibling love. And for a coven, like a family, they engage in mutual cooperation, care, and defense. So sure, they might target a rival witch from another coven, but they feel kinship within their own coven, for the past assistance they all received from each other in getting to where they are. Don't make your witches so relentlessly evil. IRL sometimes a family member kills another family member, but for the most part siblings can get along because they know each other, had the adventures and trials of growing up together, and survived to adulthood by mutual defense and sharing of resources, with mutual efforts to secure income or resources. Witches could feel this way about their coven, even after they have "graduated" from the coven and are on their own. Edit: This comment (by Ben Barden) is important enough to add here, so it won't be lost if comments are sent to chat: > > The fact that they regularly hunt and murder other people means that they probably don't have many other friends. Humanity is a pack animal. Especially if you live in a world where everyone is out to get you (because you keep murdering them), having friends you can trust is useful, so that you have backup when the witch-hunters arrive. > > > And perhaps this is true even for the ascended; if not, then the ascended may still wish to protect their "younger" sisters and see them ascend as well. Perhaps the ascended, too, were protected by "older" sisters that ascended before them, and it is part of witch culture to remember where they came from, and that is part of why civilians have such a hard time eliminating covens. Edit 2: In fact, if this isn't part of witch culture, it makes little sense to join a coven! Because somebody is going to be the first to ascend, almost certainly somebody older, and if #1 is "evil jealous" and ascends, then the smart thing for #1 to do is keep anybody else from ascending; including the #2-9 in their own coven. If all witches are "evil jealous", then as a young witch so am I, so why should I help somebody else ascend and gain the power to kill me? Or the OP's question cuts the other way: Shouldn't us lesser witches try to kill #1 right before she ascends, to protect ourselves? I think a high degree of mutual trust has to be part of the culture of a coven, or it falls apart before anybody ascends. [Answer] # You Inherit Pieces of the Other Witches The Aether doesn't just flow directly from the victim to each of the 8 witches individually. While most of it does, some of the aether reaches each witch after passing through a different witch. This means that while a witch will develop special traits and transformations according to their inner selves, these will be slightly influenced by others in the coven--a witch may even inherit a piece of another witch's trait (or a weaker version of it). This means that a witch wouldn't join just any coven--not unless they're truly desperate, but what coven would want a witch like that? No, covens are formed carefully, each witch analyzing the others, making sure that their inner traits will be mutually beneficial. This also means that after a complete apotheosis, a witch has inherited a little of the nature of the other 7. Both the completed witch and the others can feel the new connection. They are of each other--they have traces of the same aether flowing through both of their bodies. And how could you kill a piece of yourself? This new bond makes the witches like siblings, where the complete apotheosic witches strive to protect the others in the coven and help them to also achieve apotheosis. [Answer] Magical Upkeep Even though they are biologically immortal, using their power drains their mana. They'd still need to participate in the ritual to replenish their magic fuel, and hence would need to keep the coven around. Moreover, a transformed witch has the ability to extract life force more efficiently from the sacrifice, even if it is getting divided equally, so keeping more ascendants in the coven would be tolerated. Introduce Someone Meaner Witches may be hunted by or in battle with sorcerers. Even an ascended witch may fight only toe to toe with a sorcerer. The existence of a coven may increase their chances of survival, and also promote encouraging other coven members to ascend to fight of the Sorcerer cadres. Competition Covens may be in a power struggle within the witch-kind as a whole. This will lead to a system where covens will try to recruit stronger initiates, and have them transform as soon as possible and keep them around to strengthen the coven against other covens. A coven with a majority of witches fully transformed will of course be more feared than one where only one is. [Answer] At the end of the ritual, parts of the apotheosized witch's original body/soul/magic are bound to the witches that conducted the ritual. This creates a magical connection to the other witches where the apotheosized witch can not hurt them. Alternatively, if the witches die that contain the apotheosized witch body/soul/magic, that witch could weaken, lose their immortality, or outright die. [Answer] The coven would stay together to stave off the dislocation of their minds in the bodies they cheated to acquire. Normally it takes a paragon of virtue 100% attuned to the vision of their perfect self a lifetime of discipline and self-sacrifice in order to naturally achieve apotheosis. Once in that state, their minds and their bodies would be in perfect accord and as they continued to live the body made in the perfect image of themselves would be able to change as well. The witches in the coven, however, cheated the process and used magic to achieve apotheosis. Because of this, their body is in accord with their perfect self at the moment of time apotheosis occurs, but their mind doesn't possess the strength of will, focus or vision to shift their "perfect" image of themselves as they grow and change over time. This means that as their minds changed over thousands of years their body would stay the same. Imagine a vain witch whos image of beauty changed over time running across another god who is "gasp" prettier than she is... Or a witch who achieved apotheosis in an age where fat was pretty and is permanently stuck with 40lbs of extra girth. Or even a witch who wanted to be young and beautiful forever... only to realize that she is older now and wants to be treated as such. The solution to this issue is to use the exact same ritual used to achieve apotheosis to recenter the mind of the witch with the ideal version of her self periodically. This makes it important to keep in contact with the old coven and on good terms because, lets face it, any witch you come across has a decent interest in murdering you as part of their own ritual... at least the witches in your coven were able to be trusted long enough to help you achieve apotheosis. [Answer] ## Magical induction ritual To be able to join a coven a witch must undergo a ritual promise that they will be loyal to the coven. Otherwise the witch is not welcome into the coven. The terms of the contract state that the witch must always help the other members to the best of their abilities. This magic pact affects witches even after apotheosis. Some pacts may be limited time to encourage new members (and maybe carefully planed backstabbing). The pact is enforced by magic itself and dire circumstances might befall those who try to break it. Or it may simply be impossible to not abide by it once the oath has been taken. [Answer] ## Witch with disciples. Any powerful enough and smart enough witch has followers - younger witches which just teaching magic. When disciples reach certain level, the mentor could create coven from subordinates. Since mentor has superior knowledge and power, attempts to kill her are very rare. During ritual, each witch increase his power by same level so mentor still stronger (and much more experienced). When mentor witch become semi-god, rituals are stopped. On one hand, follower witch never reach the maximum level. On other hand, it would get some assistance and protection given by mentor and before-top level is still very high. Single witch could only dream about such power. Witch couldn't leave the conclave and establish its own for some reason, or it's very hard to do (mentor witch is one but not single reason) UPDATE Semi-god level is rare and nobody could say it's a top level. That's why 'mentor witch' don't kill subordinates: probably she could level-up again... if disciples become stronger, or victim would more appropriate. Why follower withces needs protection and why semi-god witches are not conquer the world, is up to you. In other answers there are great suggestions like rival conclaves or persecution from inquisitors/sorcerers. [Answer] Greed. Why do billionaires continue to expand their fortunes? They want more! Yes, your witch has achieved an ultimate state. She may be 100 times more powerful than her sisters... but she wants 101. Continuing to participate in the circle will help her power continue to grow, even if not in as dramatic a way as her transformation... and someday she may need to employ this additional power if she is to prevail against another super-witch. ]
[Question] [ I'm not sure if you guys are familiar with Michio Kaku, but he's a renowned physicist who has often talked about humanity's role in the future. He mentions some valuable words about how we are still a [Type-Zero civilization](http://www.destinationinfinity.org/2010/12/12/type-0-1-2-3-civilization-michio-kaku/) who has not even "conquered the Earth" - and still suffer great losses from natural "disasters" (as we call them), our transportation is often halted by weather (snow + tires, boats + waves etc.). If we had sustainable domes, could we not control the infrastructure inside the dome? Cities like Boston / New York could greatly benefit from blocking out snow/rain etc. What's stopping us from building a glass cage? Controlling the air quality. Wouldn't it also be great progress towards creating a modular environment to use on Mars or something? PSA: I'm just a techie-leaning entrepreneur, and I'm curious what expert opinion is on this matter. EDIT: I'm highly interested in discussing the benefits of a dome, and I welcome discussion regarding a future that might benefit from opening up this space. EDIT #2: Since this question got quite popular; cost aside, a little (or large) follow up question: would investing in this type of technology be beneficial in the coming decades when we do inevitably begin to explore other planets, as Elon Musk and many others are beginning to dedicate their careers / lives towards. Establishing a self-sufficient, modular environment could surely be of great benefit for exploration sake, could it not? What are the alternatives? [Answer] Just some initial thoughts: 1. Creating a city-sized dome is going to be very difficult. It'll have to be taller than the tallest skyscraper, and be mainly comprised of open air. Where would you put the supports? And if the whole thing is just supported by its dome shape, what kinds of materials would you use to keep it up? Due to the size of the structure, the square-cube law states that it's going to be exponentially more difficult to sustain a city-sized dome than a similar smaller structure. 2. It won't look pretty. People pay a lot of money for a great view. If you're blocking that with girders, people aren't going to be happy about it. Plus, due to #1 there probably won't be many windows, so a lot of people aren't going to be able to see any sky, which isn't good for mental health. Maybe you could put screens on the inside, but that's just more cost for building and maintenance (see #4). 3. If it breaks, you're responsible for thousands of deaths. Not only is it difficult to build such a massive structure, but when something goes wrong (and something will go wrong), you've now got random debris falling onto your city. If the whole thing comes down (think World Trade Center 9/11), you could be looking at the complete destruction of your entire city. Sports stadiums already have a problem with their domes coming down in the event of bad weather; now take that problem and multiply it by a thousand, and put a bunch of children underneath it. 4. Who's going to pay for it? This is the absolute largest building project in human history, and no one's going to be able to live/work in it. The city itself could pay for the construction, like they do for roads and such, but no one's going to agree to the massive increase in taxes, especially since it'll probably take decades to build. 5. It doesn't really help. I bet after a few years/months/weeks, there will be leaks, and it'll probably cost a fortune to send a crew up there to fix it. Due to travel to/from the city, you're also going to need to make some entry/exit points, which will let water in in the event of a flood. As for temperature control, I don't want to pay money to keep the sky above my head cold in the summer and warm in the winter. I'll just pay for my apartment to stay at a good temperature, and everyone else will probably do the same. 6. Construction will be a nightmare. I can't even begin to think of how this would actually come together, but I imagine it would involve a lot of road closings, scaffolding on the sidewalks, and hard-hat areas. It would be a massive pain for the city's inhabitants (the people who are already paying for something they'll probably never see completed in their lifetime). 7. Think of the future. In a few years/decades, our cities may look vastly different than they do now. Robots and Internet may mean that people no longer have to leave their homes, or at least can afford to work from home on snowy days. There are many proposed uses for flying drones, from surveillance to shipping; whatever their use, there may be a lot of drones in the sky in a few years, and it's not going to help if there's a giant dome in their way. There are many other technologies that will continue to advance, and many of them will make a city-covering dome less useful than it may be currently. Some of these technologies may even make it cheaper, safer, and easier to build a dome, making the people who jumped the gun seem quite silly. 8. Think of the alternatives. You could just cover all the roads. Build the roofs into existing buildings. The smaller size means less materials and less stress on those materials, which means less cost. Plus, there's less open, unused air in the system, and thus less air to ventilate/regulate. People can't fly, so focus on covering everything close to the ground, and you may be on to something. [Answer] Engineering I suspect there would be extreme engineering challenges in building a mega-structure like this. It needs to hold up, be extremely reliable, and resist inclement weather. Up to and including major hurricanes, tornadoes, or ice storms. And imagine building one in earthquake country... Money High initial cost, high maintenance cost, liability insurance if part of the dome fails. You would also face pressure from existing industries (snow handling, roofing, etc) that would lose business from the change. Insufficient Benefit Large parts of your cities are already enclosed. We call these "buildings". The dome only provides a benefit to outdoor areas and outdoor transportation, and only when weather is causing problems. So the majority of the time it doesn't really do anything. [Answer] Cost is the short answer. Building a single transparent dome over Boston would cost more than the Big Dig many times over and what does that achieve? Ecological Complexity Where Ma Nature used to take care of eliminating pollutants, we have to do that now. Plants and animals that stay or are trapped in the dome, now have different competition pressures with unknown consequences which we have to fix, manage, mitigate or eliminate. Most solutions to ecological problems aren't cheap. Now, with a contained atmosphere, we have to manage it ourselves. If grime builds up on the dome, and it will, we have to have a way to clean it. Again, that's more maintenence costs. Too Big to Build I don't know if humans have the engineering ability to build city sized domes yet out of glass or plastic. You would want to build smaller domes first and there's not any economic reason to build smaller domes yet. In other words, there's no problem that a dome can solve that can't be solved more cheaply using a different technique. Building a structure tall enough to cover the Prudential and Hancock buildings is very difficult. Convenience not worth the cost Give the T's abysmal performance last year and all the money spent on fixes, a dome costs more initially and much higher operating costs than fixing the T. [Answer] It's unlikely to be a mega-structure, more likely to be a large balloon or polytunnel or even a bouncy castle, maintained by marginally higher (and controllable) internal air pressure - a fraction of 1psi, and possibly within the normal range of atmospheric pressure variations. And no girders to block the view. 1 litre of some polyolefin (about 1 kg) would cover 1 m^2 with a 1mm thick layer : use a double layer for redundancy. Weight is about 19.6N for 1 m^2, or only about 20Pa (0.2 millibars) increase in air pressure will support the weight. More than one form of redundancy, with structural "sausages" in a geodetic layout, providing support in case there is a local failure of the main membrane. Such local failure would have to include potential aircraft strikes. If we concurrently transition to the hydrogen economy, we will need large reservoirs above our living space to contain hydrogen (generated by electrolysis of rainfall using semi-transparent solar cells) in which case we may not need to be concerned about the weight of this structure; it can be largely self-supporting (in addition to support from the higher internal air pressure). During sunlit hours, the hydrogen structures inflate and increase buoyancy as we generate hydrogen; at night, they deflate so we may need to increase air pressure (or pump up the sausages) as we consume it, to maintain structural integrity. Cost may be dominated by materials? So [Boston](https://en.wikipedia.org/wiki/Boston) (about 250sq. km or 250 million sq.m) would require in the region of 0.5 million tons of structure., made from a couple of large tankers of oil. So the dome itself is surprisingly affordable in raw commodity terms, even if you need to replace the outer skin every couple of years until UV protection improves (or the solar cells absorb that). It's more likely that pumping air to maintain pressure balance will be the important factor in the cost. Supporting and draining rainfall and worse, snow, is likely to be just one of the more interesting exercises. As is maintaining the internal environmental conditions, but other answers have covered that : I think at least we can establish the feasibility of the basic structure. It may well be adopted first in marginal farming areas to extend the practical growing season by conserving solar heat, and by controlling rainfall and excluding pests, on a field or square mile basis, rather than initially in a large city... [Answer] lots of good answers already, but there's one no one seems to have mentioned which, coming from the UK, was the first one I thought of. Say you overcome all the problems everyone has mentioned and build your mega-dome surrounding your city. It's great, your city is now completely immune to all natural disasters and adverse weather from a light dusting of snow to a mega-tsunami. As a result, everyone wants to live in your city. Your population increases, you look to build more houses, flats, etc and......oh. Your dome is full, your city can't expand without doing the whole mega-project over again. For examples of something like this which has happened, look at every European city dating back to medieval times. They all had walls once, to defend against barbarian hoards. Look where the walls are now, they certainly aren't outside the city anymore. Come to think of it, since this is WB, that might make a good basis for a story in your world. What happens when the city expands/wants to expand too far? [Answer] A very nice realisation of efficient "weather insulation", is the Khan Shatyr Entertainment Centre, in Astana, Kazakhstan. [![enter image description here](https://i.stack.imgur.com/UltCA.jpg)](https://i.stack.imgur.com/UltCA.jpg) [![enter image description here](https://i.stack.imgur.com/dLGL3.jpg)](https://i.stack.imgur.com/dLGL3.jpg) Off course it is not city sized, but building sized and it is not a dome, but a tent! The temperature stabilisation is achieved both in the super hot summers, with air circulation (profiting from chimney effect and venturi effect with the winds at the top), and in the harsh winters, as the top can let sunlight in to take advantage from greenhouse effect. The tent structure resists very well both to wind and snow. It is also relatively easy to build, as you can just start with the central pillar, pull the outer cables and finally complete the covering. Note that this works very well also with irregular shapes of the base. It will not be super-hard to adapt the concept and cover small villages/towns, and maybe even obtain a metropolis connecting many of these together. Looking at the drawings above we may expect to have an optimised base diameter reaching about three times the pillar height (in a dome you only get two). The width of Manhattan is approximately 3 km, which means that you can cover the bottom part of it with a central pillar about 1 km tall, taking care of moving the annoyingly tall building of the WTC close to the pillar. This looks super challenging, but not crazy (except moving the WTC, that is crazy). Still all the objections raised in the other answers are relevant: how much will it actually cost, is there really a need for it, will it look nice? [Answer] I can think of several reasons off the top of my head that our current civilization has not done such a thing, and probably won't without other technological advancements: * In the 90th or better percentile of situations, the natural movement of air across the earth's surface, coupled with the changes in temperature, atmospheric moisture etc that it brings, is a very good thing. Rain is free irrigation, and absolutely essential to replenish water reservoirs that humans build to sustain the large population centers we're now going to enclose. When winds and rain reach extremes, that's when things get interesting, but these developments are regional, seasonal and short-lived. Building a traditional glass dome to hurricane strengths would only help cities impacted by hurricanes, and there are very few structures we can build above ground larger than a single small room of a house that can withstand a tornado. * The dome couldn't be purely transparent across the entire surface. Anyone who thinks differently is dramatically overestimating the strength of any such transparent material or our ability to make something that large in one piece. That means the dome will need opaque structural members, which will cast shadows and reflect light (depending on the material used) on places under the dome at various times of day. In the DFW metro, there's a section of the Dallas Museum of Art called the Nasher Sculpture Center. Nearby, Museum Tower, an upscale condominium complex with a glass exterior surface, was completed in 2013, with devastating effects for the Nasher Center's outdoor sculpture garden. Museum Tower's glass exterior reflects additional light onto the Sculpture Garden, raising its temperature and frying the plants. The reflected light and the structure of the tower has also "effectively destroyed" a piece of art built into the Nasher Center, "Tending (Blue)", which was designed to be a window showing only the sky itself with no effects of human development or ground features in view no matter where you stand to look at it. The Tower's top stories are now visible in that window, and the reflected light is visible in the surrounding "frame" of the work. A dome's supports, hundreds of feet thick and extending thousands of feet into the sky, are sure to cause other disturbances along these lines, only magnified that much more by the project's scale. What if it turns out that a seam between two of the dome's panels acts as a magnifying glass, shooting a searing ray of light and heat across a narrow swath of the land under it every day? How many would be blinded? How many homes would be destroyed? We likely wouldn't know until we'd built the thing, and then it's too late to stop the damage. * Human development, while often radial, is not circular; the Earth's surface is too uneven, and the things that make locations on the Earth's land surface desirable for human habitation are too irregular. If you try to draw a circle around any portion of the Eastern Seaboard over which to put a dome, you'll see the issues involved; at some point the dome will cut right through an outlying but well-developed town. You could have domes with "warts", basically looking like a clump of bubbles specifically tailored around existing development, but this increases structural weak points as well as the number of opaque structural members supporting the transparent panels which would affect sunlight. * The tallest developed point in New York City is 1776 feet above ground level (Freedom Tower, currently under construction on the site of the former WTC). That tower, like the WTC towers before it, is an economic and architectural feat. To build a spherical-section dome over the city of New York tall enough to encompass that tower and sturdy enough not to collapse under its own weight would be a megaproject dwarfing the cost and scale of any the world has undertaken. * Many, most even, of the world's major cities are coastal (even if they didn't start that way, they were established only a few miles upriver beyond the brackish estuary, then grew back toward the shore). The primary exceptions still have access to major rivers, because humans need water. Building a dome that could seal the city away from the effects of weather would require anchor points far out beyond the shore, and for some points, even beyond the continental shelf. That's especially true of a city like New York, whose tallest points are in downtown Manhattan, closer to the water than they are tall. Even doming a landlocked major metro like Dallas would require letting the Trinity River run through the dome. * Most such proposals for a dome world assume air and sea travel has become a thing of the past. It hasn't, yet, and in fact these modes of transportation are only becoming more important in the interconnected global economy. Further complicating matters is that most major cities have major airports in the center of those cities which would require the dome to have fairly large openings that really could never be closed (a plane takes off or lands at Chicago O'Hare every 75 seconds). Similarly, the dome would have to e able to be opened Until a world ground transport network is built that makes ships and planes obsolete through some combination of cost, speed and capacity, domes will be useless at their purpose of controlling the climate inside them, because they'll have to let outside air in most of the time. * Weather's power is truly awesome. Especially when we don't respect it. Citigroup Center (601 Lexington Avenue, Manhattan, NY) is often called "New York's greatest disaster that never happened". The building is raised on massive "stilts" to preserve an historic church on the site (which has since moved). For architectural novelty and to keep the location of the church in the same place at the northwest corner of the building's footprint, the stilts were placed in the center of each face of the building instead of the corners. However, a miscalculation of the load on the building's structure in certain wind conditions led to the building as originally built being structurally unsound in high quartering winds (hitting a corner of the building instead of a face), which led to a secret scramble to reinforce the main column supports. Halfway through the reinforcement job, Hurricane Ella developed in the Atlantic and looked like it would head right for Manhattan, which would have been an unqualified disaster for the building and midtown Manhattan. As it was, Ella swung away from New York and the reinforcements were completed. Should we build a dome over New York City, or any part of it, that turns out to have a similar engineering flaw, the result would be the collapse of the dome over one of the most populous cities on the planet, with the loss of tens of millions of lives, which would very likely be a higher death toll than the weather event itself would have caused. [Answer] * The volume of air inside such a dome is massive. Building the infrastructure to move and scrub the air would be a huge engineering project on its own. For environmental benefit, you could build the exact same air-movers and -scrubbers in the exact same city (without the dome) and get at least the same reduction in pollutants and increase in air quality. The lack of a dome would likely make their job even easier, since the natural winds and rain would do a tremendous amount of the air cleaning. * The lack of air quality in cities is primarily a result of the activities going on in the city. Putting up a dome does not block out these pollutants; it traps them inside. * Yes the occasional heavy snow can shut down a city for a few days (and longer, rarely). The amount of money lost to businesses during this time is completely insignificant compared to what it would cost to build and maintain a dome. * If you did manage to build the optimal transparent dome, you would then have to deal with a tremendous heating problem. Such a large "greenhouse" would trap an enormous amount of heat. [Answer] Just wanted to give some pointers to a very well debated question: 1) Although it does seem be economically unfeasible to build domed cities on Earth, on other atmospheres such as the Moon or Mars, that would be a requirement; [unless some sort of terraforming is done first] 2) Probably, it would be better to build a structure in the wind fronts to deter hurricanes, for example, since they follow a somewhat regular pattern. No need to mention that it could be disastrous if not done properly (example: change weather undesirably on other locations) 3) If we had some sort of 'shield' tecnology (star trek like), it could be turned on only in the events of a storm or blizzard. That would be ideal, since it would save energy. 4) Let's not forget about what I call the 'Dubai Effect'. Pretty much anything you can imagine can be build, if you have that spare money. Oh, and by the way, I guess that says that I'm a trekkie. Best Regards, D.Alves [Answer] Current plans (unless I am outdated) for the NorthBay Google headquarters include plans for a dome by Bjarke Ingels and Thomas Heatherwick. [google dome article](http://www.theguardian.com/artanddesign/2015/feb/27/googles-new-headquarters-upgradable-futuristic-greenhouse) It is rather close to a bird sanctuary, which I would see as a big problem. [Answer] 1. It's going cost a bunch, and you (yes you!) will pay for it with your tax money! 2. It's going to look really ugly. 3. How is any precipitation going to make it in? We need it, and honestly it doesn't cause too much trouble. It's more trouble to get rid of it. 4. Extremely dangerous to build, and extremely dangerous to have up. 5. This would be the hardest thing to build ever, and I don't think humans are capable of doing this just yet. 6. There isn't really much need for it. In the future, if the weather (rain, snow, etc.) becomes deadly, then it might become something to think about. [Answer] It's actually technically feasible. Shadows would not be a problem. Brian Drummond came close but missed the target--you neither need nor want an inflation system. Build your dome of light, clear material with cables to provide strength, leave openings where roads come through (and if you built it right cutting new ones will not be an issue), provide controllable vents up the surface at many locations. Note that cities produce a lot of heat. When they're built on a smaller scale what do we call a bag over a heat source? A hot air balloon. You have built a tethered balloon that supports nothing but itself. Now for the disadvantages: You just created a giant pollution trap. You had better not put a dome like this over any city that uses fire. I don't see the rain being a big issue--yes, it won't rain on the city but the rain that would have fallen on it (and likely a lot more) will fall onto the dome and thus go down to it's edges. So long as the volume of water doesn't damage the dome it's no harm done. Consider what else we call a big transparent container? A greenhouse. The city underneath is going to be considerably warmer than it would otherwise be. That might be a good thing in a cold climate, a very bad thing in a hot one. ]
[Question] [ # Background There exists a continent on the scale of Eurasia, which spreads from tropical regions to polar. It has the full range of biomes that we find on Earth. On this continent, there are many varied wild beasts. All animals that are extant in the present day Americas may be found there, as well as all recently extinct animals on [this list](https://en.wikipedia.org/wiki/List_of_North_American_animals_extinct_in_the_Holocene). On this continent, there is only one type of 'magic,' and that is blood magic. A blood shaman gains his power by killing a beast and drinking the blood from his still beating heart. The animal must be killed with a sigil-blade called a blood knife, made from a special stone. This 'knife' can in fact be of any size, formed into a sword or a spear. Once a blood shaman ritualistically kills a beast, he gains the power of the animal. Any strength, senses, or abilities of that creature can be utilized by the shaman; but there is no shape-shifting involved. Here are some examples and limitations. * Strength is gained by motion: If a shaman kills a bear, his punch will hit as hard as a bear's. If a shaman kills an alligator, his punch will hit as hard as an alligators (i.e. not that impressive). He will have an unbelievable bite force, but that may be hard to weaponize given the limitations of human teeth. * The shaman must have the 'parts' to gain the ability: A shaman who kills a deer can run 40 mph; a shaman who kills an eagle cannot fly, because he does not have wings. Similarly, a shaman who kills crocodile can't swim any faster, since a crocodile swims with its tail. But a shaman who kills a sea lion can, because a sea lion's flippers are just feet. * 'Passive' abilities count: A shaman who kills a bison can stand, naked, in a blizzard for hours without trouble. A shaman who kills a camel can do without water for weeks. A shaman who kills a jaguar can move silently. Passive abilities don't depend on body part; you don't need a hump to go without water, or fur to withstand the cold. * The animal's final state is important: A wounded or trapped animal will not pass any of its powers on. This is important, since you cannot trap a beast in a pit, then kill it to claim its powers. The first strike on a healthy animal must be done with the blood knife or the blood magic will not succeed. * The abilities lose scale with the size of the animal: A 150 lb shaman that kills a 150 lb deer gains all of its speed and agility. A 150 lb shaman that kills a 15 lb rabbit gains at best 1/10 of its speed and agility. This doesn't work scaling up; a 150 lb shaman that kills a 15000 lb mammoth still gains only 100% of its abilities. It is considered shameful for a blood shaman to take the (meagre) powers of an animal much smaller than a human. * You only get the maximum of all animals you've killed: Killing two deer doesn't increase your speed twice. Killing a deer then a cougar only lets you take the best of either of their speed and agility. # Problem statement Training to be a Blood Shaman is arduous. First you must master the spiritual powers needed to perform the rituals; then you must master the physical powers needed to kill your first beast. To ensure that this path is attainable, there is a standardized path of beasts you kill in a certain order as you ascend in skill at blood magic. What is this path? ### Considerations * Remember, there is no trapping or pre-wounding the animal. The first wound of the beast must be done with the blood knife, or the blood magic will fail. * The starting point is a plain old human with a knife/sword/spear, albeit one in fine physical condition. The ending point is the mighty [mammoth](https://en.wikipedia.org/wiki/Columbian_mammoth). Few, if any, blood mages have ever attained its power. * The blood shaman must be expected to have at least even odds to kill each creature with only his blood knife. For example, if the last step was killing a cougar, it would be reasonable for the next step to be a horse, since cougars can kill and eat horses. If the last step was a deer, it would not be reasonable for the next step to be a bear, unless some special tactics were involved. * Biome is no limitation on order of animals. Tropical and arctic animals can be mixed in any order. Blood shaman are expected to span the continent in their lifelong quest. * The correct answer will get from human to mammoth in the fewest steps while never requiring the shaman to undergo unreasonable odds to kill another beast. A good answer will use the special abilities of one animal to tackle the next one in order. [Answer] ## Do start small Killing rats or rabbits may be dishonorable for a full grown, ready-for-the-title shaman. But it may be part of the training for young, unprepared shamans. This is important, because once they are ready for their first real challenge, they may have heightened senses. Killing a house cat will not grant you much in strength nor speed, but you will have improved hearing and smell senses, however small the improvements may be. Though, if the first kill ever to grant powers should already be done when the person is already a proper shaman, this section should be disregarded. ## Start with a predator One could think that game would be an ideal first choice. After all, humanity has been hunting game from the start. But game tends to run away. And the usual method of game hunting without traps is either with bows and arrows, or with many spears. Making a lot of ritual weapons and throwing them around while trying to one-hit-kill game is wasteful. The perfect starter is the alligator: Pros: slow (easy to hit), heavy (grants full power), will provide ability to hold breath for much longer than a human can withstand (good for stealth, dampen breathing sounds), ability to stand still like a rock for hours (also good for stealth). Great if you are doing your hunting on swamps, marsh or mangrove. Cons: not much in speed nor damage capacity, practically a lost battle if you can't lure them out of the water. ## Next, develop your stamina Once you have offed a gator, you can hunt big game. You will be able to hunt like a giant mantis. Cover yourself in mud for camouflage, then wait by where game goes to drink water. Use your ability to hold breath and stand still, and wait for your prey to get close. Now remember, you killed an alligator before. Gators can perform quick bursts of speed, so use that skill. When a bison or buffalo comes near you, be fast and one-two-THREE-DEATH it with a stab to the jugular. The rest of the herd will run to the hills. You now have even more stamina and raw strength, and a lethal kick if you need one. ## You need some speed too You are almost ready to tackle the mammoth. Just need to take a detour first. Kill a wild horse. Seriously. You have the stamina to chase one - it may be faster than you - and you want that speed - but you should be able to track and pursue, with your buffalo/bison stamina. If you think a tired horse is no source of power, let it rest and ambush. ## Now the final leg Offed the horse? Cool. Now, to kill the mammoth: * Make sure to reshape your weapon into a giant spear (or acquire a new one in that shape); * Find a mammoth; * Point and run as fast as you can. With the force of a bison and the speed of a horse, the spear will enter the mammoth like an arrow piercing a naked human. It will probably break, along with some of your own bones when you collide with your victim. But then again, you can't make an omelet without some exposed fractures. Enjoy your mammoth heart. ## That doesn't have to be the end of it You could try croaking some other critters for additional powers. I'll leave the methods of killing to the reader's imagination from here on. * Great white deaths: who cares that human teeth are hard to weaponize, when your bite can break the hardest branches and turtle shells as though they were cookies? * Sperm whales: hold your breath for up to 90 minutes! Stun your prey by busting their eardrums with 170 decibel shouts (200 underwater)! * Anacondas: eat as much as you can fit in your stomach then rest (but not sleep nor hibernate) for 2 to 8 weeks. Not very adventurous, but nice if you need to save energy for a long time and you can only have one large meal. * Goats: American alpine goats may weight as much as an adult human (75kg). Goats have a sense of balance much more refined than that of humans, which helps to keep one's footing in all situations, as well climbing steep surfaces or perilous terrain. [Answer] Obviously, you kill another blood shaman and gain 100% of his abilities. Befriend a shaman as his "pupil", wait till he trusts you then, when his back is turned, ... WHACK! Not very honorable but, hey... fast tracked. You never said blood shamans can't get the power inherited by blood shamans. --- If domesticated animals are allowed start with a dog, maybe dogs bred just for this purpose. You would gain * enhanced sense of smell * enhanced sense of hearing * endurance, some dogs have high endurance * a craving for milkbones Of course that brings up issues where you could have a whole host of domesticated animals that grain all kinds of base abilities. Hunting hawks, etc.. Here fido, good boy ... WHACK! where do you draw the line at "caged" --- I would start by using the biggest weapon mother nature has given man, intelligence. Man is capable of understanding the behaviour of other animals. So for example you could start putting food out for deer. Get them used to that, slowly get them used to being fed. Get closer and closer until ... WHACK! [Answer] # Start on the beaches You want a seal. * Approximately human sized * Not particularly agile on land so easy to hunt * Have the ability to swim quickly and remain underwater for long periods * Survive in both very cold water and very cold air comfortably You're now all set to hunt a crocodile, or hunt like a crocodile. I would advise hunting a crocodile, wait on the bottom of the river and attack from below. * Survive up to a year without eating * Impersonate a floating log (it could be useful, you never know!) * Digest anything, no matter how rotten, without adverse effect Now you're really hunting like a crocodile, lying in ambush in the river waiting for the migratory herds. You may be considering the speed of a pronghorn at this point, but they're too small, the reason you want a deer species is the ability to [pronk](https://en.wikipedia.org/wiki/Stotting), this will save you from needing to hunt a big cat for its leap. You might as well go for bison for brute strength (try not to get caught under a stampeding herd) and a horse for speed (possibly before the bison so you can run away in time). You now need the stealth of the cats, you get to take your pick here but they're all dangerous. The first thing to do is make sure you're hunting him, not the other way round. Cougar and jaguar are both quite big enough to get their full abilities, they're also quite big enough to eat you as a snack. Given you have the abilities of the crocodilians, you're primary prey for a jaguar whose way of saying hi is a crushing bite to the back of the skull. You have the strength to take them on head on, the speed to outrun them, the reflexes to evade if you spot them, the sense of smell and hearing from a lot of prey animals, but they're ambush hunters. The best way to deal with the cats will be out in the open, the endurance hunt. Listen for the alarm calls of the prey around and start your hunt. It doesn't matter which of the cats you go for this way but you have to keep your target running, preferably out into the open. Once you have your big cat, you're all set. * You have the speed and endurance of the hunters and prey of the open plains * The patience and digestion of the crocodile * The stealth of the cats * The cold tolerance of the seal * The swimming of the seal * The breath control of the seal and crocodile * The strength of any of the above [Answer] # Take advantage of terrain You have to take what you can get for your first kill, since humans are not super competitive in hand to hand combat against a lot of beasts. So a great way to get your first kill, but add useful skills is to tackle a creature out of its primary environment. That means, ambushing and killing an alligator or crocodile on land. With your blood knife fashioned into a spear, kill an alligator from above, attacking out of a tree. With the crocodillian slain, you will gain the ability to wait motionless for hours or days, and the quick powerful lunge necessary to tackle flightier prey. # Get some stamina With some serious aquatic ambush skills, you can now try to tackle a creature that you would never hope to outrun. We are not looking for burst speed so much as long distance stamina. [Popular Mechanics](https://www.popularmechanics.com/adventure/sports/g418/animal-kingdom-top-marathon-runners/) suggest that pronghorn, camels, and ostriches have very high stamina. Pronghorn are around in this continent. Camels might be a tough kill at this point due to their size, but there are lots of smaller camelids such as guanaco, vicuna, and two [extinct](https://en.wikipedia.org/wiki/Hemiauchenia) llama [species](https://en.wikipedia.org/wiki/Palaeolama). Finally, there are no ostriches, but there are rhea. These max out at about 40 kg today, but if they were a bit larger in the past, they would be a valid animal to kill for stamina. Ambush one of these creatures in a water hole, kill it will a quick burst of speed and powerful thrust of the blood knife. # Run something to death We don't have a lot of strength and power yet, but we have the tools to get it. Many large herbivores have as their natural reaction to run away. But we can now outrun them over long distances, no matter how fast they are. We will simply run them to death. The target animal should be one that can killed after being worn down tired. A bison is probably still too large to risk tackling, but a horse, musk-ox or elk might be the right size, or possibly one of the extinct [musk-ox](https://en.wikipedia.org/wiki/Bootherium_bombifrons) like [bovids](https://en.wikipedia.org/wiki/Euceratherium). Another option for a more jungled chase is a large tapir, but chasing though water might not play to our strengths. # Get the ability to leap attack Hunting a predator is hard, because ultimately, they will turn and attack you. While a spear is a useful weapon, so are teeth and claws. To overpower a predator, you really need to be stronger and tougher than them. Now that we have killed a horse or elk, we can match a big cat strength for strength, and hopefully, with our spear, prevail. Hunt down and challenge a cougar, jaguar, or maybe [Homotherium](https://en.wikipedia.org/wiki/Homotherium). # Use your leap attack to gain great strength Now that you can ambush and make a jumping attack at a truly powerful beast. To tackle something much stronger, by yourself, you will have to leap on their back, and try to damage them sufficiently in the first blow to even the fight. With the leap of a jaguar and the strength and mass of an ox, you can tackle a [short faced bear](https://en.wikipedia.org/wiki/Short-faced_bear), a ton and a half [ancient bison](https://en.wikipedia.org/wiki/Bison_antiquus), or a [giant sloth](https://en.wikipedia.org/wiki/Megalonyx). # Almost there The gap to the Colombian Mammoth is still an order of magnitude at this point. The previous animals were in the 1 ton range; a Columbian mammoth is more like 10 tons. To bridge the gap, we'll have to use the only animals left: [Mastodons](https://en.wikipedia.org/wiki/Mastodon), [Megatherium](https://en.wikipedia.org/wiki/Megatherium), and [Eremotherium](https://en.wikipedia.org/wiki/Eremotherium) in the 3-5 ton range. # Conclusion The standard order for a blood shaman is * Alligator * Rhea * Horse * Jaguar * Short-faced Bear * Megatherium ground sloth * Mighty mammoth [Answer] Sometimes on WorldBuilding, the best answer is one which challenges the assumptions of the author. There is no best path > > To ensure that this path is attainable, there is a standardized path of beasts you kill in a certain order as you ascend in skill at blood magic. What is this path? > > > Why must there be a standardized path of beasts? You call these individuals "shamans," which are traditionally a class of individuals whose training is distinctly personal. You are using blood, which is also deemed distinctly personal. Why would one's training follow a min/maxed regimen devoid of any personality? Do these shaman care about nothing beyond raw power? If so, I may recommend changing their name to something more proper. "Death knight" has a good ring to it. Once it's personal, a lot of the rules become less essential. You don't need as many honor rules, because each shaman will be concerned with their own. You don't need to worry as much about the trapping or poisoning rules because something so intimately personal as selecting an animal implies that if the shaman cannot still the creature's heart with just his gaze, he isn't one enough with the animal to merge with it anyway. Surely merging is a frighting thing which could backfire if an untrained civilian grabbed a blood knife and tried to hack the head off a cat, dog, or horse in the name of power. Those with the spirit of the Mastodon in them must make a journey. They must find their way to the point where they can truly be one with the Mastodon, as equals, without losing their way to the cat spirits or the gazelle spirits. Or perhaps they find that their spirit was not that of the Mastodon. Perhaps they find that their spirit is something more subtle. More uniquely their own. [Answer] You all are picking boring animals. Let's go look at the extinct list! I'd start with a [glyptodont](https://en.m.wikipedia.org/wiki/Glyptodont). It's basically a giant armadillo. It's strong but slow, and a quick shaman with a knife should be able to get past its armor without trouble. Now that you are invulnerable from the neck down, it's time for some strength. Bears are the obvious choice, but I think that they are probably outmatched by the [1,000 kg giant ground sloth](https://en.m.wikipedia.org/wiki/Megalonyx). Now it's time to get some speed and endurance. Here the pronghorn is probably your best bet, if you can catch one. Sneaking up on one in the open plains where they live might be difficult, though, so you might turn instead to the majestic moose, which can clock in at 35 mph for over 500 m are excellent swimmers and can kick in every direction. For stealth and a wicked pouncing leap it's time to go jaguar hunting. And now you're ready to face your mammoth! [Answer] Step 1: You want to start out easy, so finding tigers, crocodiles, rhinos, etc would not be a good idea. The best animal to start out with would be a sea turtle. Sea turtles are powerful swimmers, can see underwater, and have very [powerful lungs](https://en.wikipedia.org/wiki/Sea_turtle#Diving_physiology). Furthermore, they are very vulnerable when they are on land, and they are not very dangerous. So wait for a turtle to come ashore during breeding season and you can easily kill it. Step 2: Find a water-hole or river. All animals need water, so all you have to do is wait for some animal, like a moose, to approach. Then you can ambush it, and kill it with your turtle powers. An powerful animal like a moose would be the best. Step 3: Practice on an African elephant. Before you go kill your Colombian Mammoth, first find an African elephant. Your moose powers, turtle powers, and intelligence, killing an African elephant shouldn't be too hard. This step is important for 2 reasons. You get to practice on something smaller and you gain the [strength of an elephant.](http://www.elephantsforever.co.za/elephants-faq.html) Step 4: The final step would be to kill the mammoth. With your incredible elephant strength, it should be a piece of cake. Attach your knife to a stick, so that it becomes an ax. Run up to the mammoth and smash your ax/knife into its skull to kill it. [Answer] * Start with a beached whale: unless it still counts as trapped when the animal did it to itself. Although it might take a long time to cut through all that blubber. * if the above counts as trapping the animal, then maybe start with a pilot whale. (See method here: <https://en.wikipedia.org/wiki/Whaling_in_the_Faroe_Islands#Elements_of_the_hunt>) Powers gained: technically, whales swim with their tails, but they can also hold their breaths for a very long time and hear sounds as low frequency as 10 Hz and can dive deep. * a frog: children can catch frogs so shamans should be able too. (But wear gloves in case the frog is poisonous.) It might be small, so the shaman would gain no awesome jumping powers but might be able to breathe through his skin. And possibly catch flies with his tongue. * barn cat: you can't say those are domesticated, exactly. And seeing in the dark and hearing mice moving in the walls would be kind of cool. * mice: to gain an enhanced sense of hearing and smell. * snake: to be able to swallow large objects and possibly "see" heat signatures. (unlikely as they have a different organ for it that humans don't possess). * an octopus: "Octopuses and other coleoid cephalopods are capable of greater RNA editing (which involves changes to the nucleic acid sequence of the primary transcript of RNA molecules) than any other organisms." <https://en.wikipedia.org/wiki/Octopus#RNA_editing> Actually, I can't tell you concrete example for which this would be good but it does sound cool. Also, the shaman might gain a better sense of direction and spatial problem solving skills. [Answer] Two steps Kill a panther. You said that this would give you magical silent-walking abilities. Killing a panther with a spear should be fairly easy for somebody who knows how to use the weapon. If you are worried that you'll die to the panther, you were never meant to be a blood shaman anyway, but you can make it less risky by simply going in a large group, this should prevent the animal from thinking you're an easy snack, making you the aggressor. Find a sleeping mammoth and a safe spot to hide from an angry mammoth. Jam your spear through one of its eyes, get out before it realizes what is going on. See if it dies from bleeding. If not, repeat for the other eye once it passes out again. Now kill your blind mammoth in whatever fashion you deem best, if being stabbed through the eyes twice wasn't enough to kill it. [Answer] # Start with the Mammoth Ancient humans routinely killed Mammoths as a source of food / clothing / housing. They normally hunted in packs and used all types of trickery (nets, pit traps, chasing the animal to die of exhaustion ... etc). However, I am fairly confident that a well prepared blood shaman could kill one on there own without having to resort to traps. Start by crafting a blood-stone spear lashed to a solid oak staff using a type of cloth. Cultivate some [Wolfsbane](https://en.wikipedia.org/wiki/Aconitum) and poison the cloth of the spear with the [wolfsbane](https://en.wikipedia.org/wiki/Aconitum) mash. Sneak up on the Mammoth and stab it in the neck. ... although you might want to start by killing a Starfish or a large lizard so you could regrow limbs (just in case). Alternatively you could kill a puffer fish first... a puffer fish has enough poison to kill 30x humans so even with 1/10th of its ability you would still have more than enough [tetrodotoxin](https://en.wikipedia.org/wiki/Tetrodotoxin) to kill most animals. [Answer] Simply put, my list is roughly three to five species long: 1. Small predator/large prey: Doe, for example. * Lone wolves would be useful, but the payoff would be smaller, due to the disparity in size. On the plus side, getting one to attack you would be as simple as bleeding, or wandering too close. * For prey, you might want to choose a doe, but you could choose a stag, as their antlers and speed come at a disadvantage, given the ingenuity of man. 2. Large prey/large predator: A bear, or more specifically, a kodiak (their among the largest/strongest bear species in the world). * With the speed and stamina of a doe, you could outmatch a bear in speed, which gives you some room with regards to the obvious deficit in strength. This should help with maneuvering in and out of the bear's range (small arms and all). * If you went for the small predator - which is undeniably harder, seeing as smaller predators run in packs - you'll have to go after large prey now. 3. Larger predator/largest prey: Mammoth, to be precise. * With the speed of a large prey animal, the strength of a large predator and the mind of a human, you could overwhelm a mammoth. We can't trap or restrain the animal, but we can corral, correct? If so, the best option would be to force it into a choke point and force it to charge at you. With the strength of a bear condensed to a point, moving at the speed of a deer, it should be possible to pierce the skin and muscles of a mammoth to get to the heart. Now, I'll give you some honorable mentions. 1. Jungle cats/large cats. * On top of being extremely fast, most big cats have impeccable balance, excellent hearing, smell and eyesight. Bears have good senses, but many of the animals in this category are a step or two above. It can only help your cause. 2. Smaller aquatic mammals would be great. You could hold your breath for an hour plus. 3. Predatory birds could be helpful, with regards to eyesight. [Answer] I see a loophole here, and it's a big one. Literally, these guys outnumber humans 200 million to one. Arthropods. In other words, your more clever blood shamans can gain the power of insects by forming a needle of the bloodstone and killing them en masse with that. Yes, it will take a while, because you only gain a sliver of power from each insect, but it's worth it! Take the Indomitable Ironclad Beetle. Its shell is so tough that in order to break it and therefore harm it, you have to expose it to 160 Newtons. For a frame of reference, getting run over on a concrete road subjects such a beetle to 150 Newtons. And after that, it's perfectly fine! Mantis shrimp are similarly game-changing. Some mantis shrimp are "smashers," which have bludgeoning appendages that can accelerate at a speed of over 50 mph! The blow from these appendages delivers a force of over 1,500 Newtons, a force 2.5 thousand times its own weight. According to factanimal.com, "if a human could do that they’d be able to punch through steel." Even worse, the punch is so fast that it creates a cavitation bubble (ie. superheated bubble with a corresponding flash of light). Note superheated-this attack will generate temperatures of 4,400 c (almost as hot as the sun) in the surrounding air, and when that bubble collapses, the result is a powerful shockwave that can stun, kill, or dismember the target even if the attack missed! A Tiger Beetle is just as dangerous-the fastest of them runs at 5mph, which doesn't sound impressive until one finds out that means it covers 120x its own length in a second, and by comparison, Usain Bolt covers 5x his body length (height) in a second and would have to run at 480 mph to cover the same distance relative to his height! Granted, tiger beetles can only see a blur at that speed, but it doesn't matter because they're so dang fast they can afford to stop and reorient themselves. Granted, since this happens because their eyes can't gather enough light to form an image, one may be able to overcome that through a bat or whale's sonar abilities. Anyway, a Blood Shaman with the three abilities should be able to take over and rule the continent with those three abilities alone, but if he wants to play it safe he can claim a queen bee or ant's pheromone control ability first and then take over by virtue of biological mind control. Forget the mammoth, it's the little guys who you really want. ]
[Question] [ I have a universe where humanity has produced various civilizations on multiple planets (and no planet has achieved a single world government); and very few of these countries possess the know-how of nuclear weapons- but space travel is possible, although it can be expensive and difficult. My question is this: Could basically all nations have the technology to be space-faring, yet not independently produce nuclear weapons? Can these two technologies be separate? [Answer] With the comment regarding theory vs. engineering, the answer becomes a clear yes. Building a nuclear weapon is a serious engineering challenge even if you have the nuclear physics down pat. Gun type weapons are slightly easier than implosion type weapons, but both have the problem of preventing a [fizzle](https://en.wikipedia.org/wiki/Fizzle_%28nuclear_test%29). The society might even run nuclear power plants. They would know that a nuclear weapon is possible, and that some of their power plant waste could be abused, but they never start the necessary R&D project to turn the theory into practice. [Answer] Yes, this would be possible. It would even be likely if Uranium (and Plutonium) were absent or exceedingly rare on those planets. Thorium works for reactors but cannot create a nuclear chain reaction by itself, so it would not work for nuclear bombs. The concept of a destructive chain reaction might be only esoteric theory or might be well-known but judged impossible to realize, as it would require mining an entire planet's supply of Uranium and then enriching it. About note 2 from the question: Thorium as found on Earth only contains trace amounts of the unstable isotopes that might allow a chain reaction. Somehow finding a very young/new supply of it might allow its use as a bomb. [Answer] Rockets don't need anything nuclear. Chemistry will suffice. For finding your way into orbit and back, electronics are a great help (and crucially, provide a great economic motivation). The peaceful but profitable uses of space travel are communications, weather forecasting, and natural resources management. Less peaceful but non-nuclear, spying and surveillance. Weapons came first here on Earth, because WW2 was the catalyst for the development of both rockets/ICBMs (German V2) and nuclear weaponry. Further, unresolved tensions between the USA and the USSR (to put it mildly) drove the further development of space technologies via ICBMs. In another branch of the multiverse, Lenin was shot by Russian royalists and Hitler died in the trenches of WW1. That world today would probably be dominated by the British empire and the USA. Would nuclear-tipped ICBMs have been developed in advance of communications satellites? I rather think that WW1 would have provided a longer-lasting deterrent to the military and that trans-Atlantic competition would be by trade, not armed conflict. Elsewhere in the universe, there are doubtless stars and planets which condensed out of a supernova remnant 8 Gyears ago rather than 4 Gyears ago. Which means that there will be something like 1/16 as much Uranium-235 available to their inhabitants, which will probably hold up the development of nuclear fission technology by a considerable time compared to electronics. (Half-life of U235 is about 1 Gyear). Further if the planet doesn't have Earth's history of a huge impact event to stir it up, a much greater fraction of the heavy elements like Uranium will be buried in the planet's core. (We don't know enough to know whether a planet with less heavy elements at its surface is a barrier to the evolution of life, or not). [Answer] Hmmm. This is asking for a lot, considering that humanity was on its path to discovering nuclear energy ever since the 1800's. Think Marie Curie, and various other scientists who experimented with x-rays, etc. It took until the 1940's for the technology to develop enough and for governments to be motivated to fund the research in order for the bomb to come along, but it would have happened sooner or later, even if WW2 had not occurred. Some ideas: Alternate Power Source I think it MIGHT be possible to skip nuclear energy if you give people some other POWERFUL energy source to exploit. For example the discovery of an alien artifact, or some strange material that we first find in the remains of a meteor that crashes on Earth (we use that material to get into space and harvest more, but at great expense). Nuclear Power Without The Bomb WW2 was averted somehow, and the scientists that stumbled onto nuclear energy did so in the context of a civilian scientific research setting, not military. That way they may give world nuclear power (by far our most powerful energy generating method), but avoid weaponizing it for a few decades. In the mean time, mankind enthusiastically researches new power sources and finds something even more powerful than nuclear energy - at that point you make some new tech up. The thing to note is that neither of these scenarios actually excludes the creation of nuclear technology, or the atom bomb. Quite simply, a lot of scientists were having similar ideas about radioactivity, and one of them would have figured it out sooner or later, no matter what. Which leads to what is probably your best bet: Aversion To Nuclear Power Marie Curie or another scientist who first meddled with radioactivity is more successful than they should have been. One of their experiments accidentally irradiates a major European city and kills hundreds of thousands of people. The governments of the world impose a ban on all things nuclear, and severely punish any who explore that line of research. As a result, alternate power sources are explored: electrical motors, solar power panels, etc. Good luck, hope that helped a bit. [Answer] Most of the answers refer to nuclear FISSION power and weapons. A couple mentioned fusion. This is usually thought of as either huge, plasma-based magnetic-confinement "Tokomak" style fusion reactors or the almost as big, beam-implosion reactors. Or as also mentioned, the boondoggled cold fusion. As was suggested, if the characters lived on worlds with little access to naturally fissionable elements, there would likely be a much lower theoretical understanding of radioactivity much less the weaponizing of said knowledge, but their sun could be a potent source of inspiration for fusion research, and as was noted, a semi-portable fusion weapon is much harder to create, if not impossible, with current technology without a fission trigger device. Another potentially useful version of fusion research is called "inertial confinement fusion". It was originated in the 1960's by television pioneer Philo T. Farnworth using a electrostatically-driven vacuum tube-like device he called a fusor. Fusion can be easily (commercially even) achieved but a net power gain has not yet been proven doable. However, the late, great Dr. Robert W. Bussard (of "Bussard ram-jet fame", AEC member, etc.) was convinced it held much better prospects than Tokomaks (after something like 20 years on them) and was involved in a company called [Energy Matter Conversion Corporation](http://www.emc2fusion.org/) (i.e. EMC2). They claimed to have finally licked the engineering problems a few years ago... just before their U.S. DoD funding ran out AND their coils burned out. Since then the surviving researchers have been mostly publicly silent, although there are some links on their website to published papers. Back in December 1986, Analog Magazine published an article by Tom Ligon, who worked with Bussard and it is now online at a website dedicated to the fusor topic [fusor.net](http://www.fusor.net/tom-ligons-anal/). The article also suggested a potential fuel, proton-boron 11 or p-B11, as ideal for a variety of reasons, including suitability for a spaceship drive and power plant. Hope that helps a bit and good luck with your writing! [Answer] You can't have thorium for your deep space work because it's not that hard to convert it into a fissionable isotope and thus make a bomb. You'll need a world virtually completely lacking in elements heavier than Bismuth. Powering spacecraft that operate in the outer parts of the star system is going to be very problematic in such an environment—the only normal RTG isotope you would have would be Sr90 I see no good way to produce this. Sr89 is quite hot, you'll need two neutron captures within a fairly short period of time to convert stable Sr88 into Sr90. Trying to create it from Rubidium won't work because the only stable isotope is Rb85—neutron capture & decay yields Sr86. Likewise, I can't find anything heavier to bombard something with that will end up with enough neutrons. Likewise, decay from Yttrium isotopes yields something without enough neutrons. Note that producing the heavy elements is likewise basically impossible. Neutron capture is stopped at Astatine unless you have a huge neutron flux (a supernova.) Bombardment with heavier atoms can bridge the gap but the results are so neutron-poor they promptly decay. If you want a world with no big booms then I'm afraid you'll have to wait for fusion power to head beyond where solar power can do the job. [Answer] It actually depends on the level of space flight you assume for your civilizations. Newtonian physics allow you to achieve space flight without the knowledge of special theory of relativity. The last is an integral part of understanding matter to energy conversion needed to create a nuclear weapon. However - even if they totally do no research subatomic structure - a spacefaring civilization will sooner or later notice the effects of special and general theory of relativity when they use sattelites for applications like GPS. If you want to generate enough power to go to outer space, you will however sooner or later need power generation through radioactive decay, fission or fusion at some point because it just becomes uneconomical to do that via conventional means. If you go a step further, and say they do not develop nuclear weapons - even if they only develop nuclear power generation (fission/fusion) - and they would be in a position to alter the course of astronomical objects, they could still also achieve the same destructive power as nuclear weapons. [Answer] Chemical energy is sufficient to get into space, and has even been used to get to the Earth's Moon and back, so we have some pretty convincing proof that it is indeed possible. Wernher von Braun wrote a pretty detailed plan for a mission to Mars based on the technology available in the late 1940's/early 1950's, which resembled a fleet action more than anything else (there were about 7 manned ships just to get there and back, and electrical "hotel" power was through the use of solar concentrators to boil mercury to run turbines). The assembled fleet of manned ships, landers and cargo craft looked like this: [![Martian expedition fleet](https://i.stack.imgur.com/K3pfY.jpg)](https://i.stack.imgur.com/K3pfY.jpg) So spaceflight, and even large scale manned spaceflight is certainly possible using chemical energy and 1950 era technology. Without nuclear power, you are sharply limited by the energy density of chemical fuels, and the diminishing energy of the Sun as you go farther into the Solar System (an expedition to Saturn could take decades using chemical rockets), but you if there was some economic, social or military invectives to carry out a space program,, then you can go into space. [Answer] Given the physics are similar to our world. The rule for creating from matter is Einsteins famous formula: E=MC2. Knowing this you would have the first step in building a nuclear weapon. It is also the same formula you use for cold fusion, nuclear power, oxygen and so on. "Could basically all nations have the technology to be space-faring, yet not independently produce nuclear weapons?" : Yes, it could be possible. Can these two technologies be separate? : It is fairly much the same principles, can you make a gasoline motor without knowing how to make a gasoline bomb. It is producing energy, the difference is just, how much energy, can it be contained, and are you making too much of it? Space Travel Without Understanding How to Create Atomic Weapons? : There is other alternative to atomic weapons, you can make an Ethanol engine without knowing about gasoline. And you can make space travel without knowing about atomic weapons, you just need to have another power source just as good. [Answer] An example that this is possible — Nuclear Fusion It's quite possible that a civilisation could understand and develop nuclear fusion power capabilities without ever developing nuclear fission capabilities. The two processes don't have much to do with each other. If it could be put under control (something that scientists are working towards right now), fusion could easily provide enough energy to travel interplanetary distances. You can make fusion work without having any uranium or plutonium, all that's needed in principle is hydrogen, so you might guess that your world doesn't have uranium at all. Making a hydrogen bomb is not possible without first making the fission bomb (the fission bomb sets off the fusion part of things), so this avoids misusing the technology to create nuclear weapons. ]
[Question] [ I am in the "drawing board" stage of creating fantasy mounts for my world and I was wondering how useful would a giant centipede-like creature be as a mount ? I am personally operating under the assumption that while the centipede-like body-plan would be quite slow and creepy looking, it could potentially make for a very stable and safe means of transportation, suitable to all types of terrain. I envision a giant and very powerful mount capable of carrying multiple people or goods, kind of like a (much) slower version of the bus. Also, though slightly unrelated to my question, what would be a good justification for the existence of such a creature, I assume that very harsh terrain might be a good enough excuse. [![enter image description here](https://i.stack.imgur.com/rPThH.png)](https://i.stack.imgur.com/rPThH.png) [Answer] A centipede would make an awesome, fearsome fantasy mount! [This video](https://www.youtube.com/watch?v=q2RtbP1d7Kg) does a pretty good, close up job of extolling the virtues of the common house centipede. Pros: * they're fast. Really fast! much faster than ants or even jumping spiders * they're highly manoeuverable! great at turning corners with lightning speed * they're a comfortable ride! if you watch a centipede in motion, its gait is essentially level * did I mention they're really fast? * they're savage warriors in their own right: centipedes are natural born hunters with venomous pincers, specialised grabbing limbs and even specialised multi-segmented lasso limbs. The competition doesn't stand a chance! * terrain is meaningless to a centipede: walls, boulders, dirt, hard surfaces; no worries there! Some centipedes don't do at all well in water and easily drown. Others take to water like a ... well, like submarine centipede! [Like this fellow](https://www.youtube.com/watch?v=q11E1qF9EH4)! * The usual tactic of attacking a large mount, such as an oliphant or AT-AT, is to go for the legs. This will be complicated by the large number of legs on a centipede. * they're creepy as hell! Cons: * this is a fantasy world: there are no cons! Justification: * entomological cool factor: what else do you need, really? [Answer] While all the pros have been well pointed out by @elemtilas answer, and most of the physics based ones can be hand waived by magic. I think there are a couple of cons worth considering just to add some flavour: * Food: Centipedes are carnivorous, so a giant centipede would require large quantities of meat. However they are not picky, so you can use your enemies as a supplement. * Behaviour: Centipedes are not territorial, but they are not generally gregarious. Not sure if you can keep a lot of them together without them starting to fight each other. Probably solvable through breeding and taming. Also other mounts, livestock and most humans would not go anywhere near them. The fear factor is cool and useful, but not always practical. * Water regulation: Centipedes would dehydrate fast in dry climates,just don't use them in a desert environment. * Stabling: Centipedes like to burrow and live in tunnel, so special stabling arrangements are needed. A centipede tunnel, cave or pit would be a cool setting! * Time of day: Centipedes are mostly nocturnal, but this should be solvable through breeding and taming. In alternative, strike at night! I think you picked a very cool mount, go for it! [Answer] Awesome idea, and others have answers for your main question. (It does however immediately bring to mind the [Worm Riders of Dune](https://dune.fandom.com/wiki/Wormrider), though these are giant worms, not centipedes.) But you also ask this: > > Also, though slightly unrelated to my question, what would be a good justification for the existence of such a creature, I assume that very harsh terrain might be a good enough excuse. > > > You might want to read this [wikipedia page](https://en.wikipedia.org/wiki/Megafauna) on megafauna: An excerpt: > > Analysis of the variation of maximum body size over the last 40 Ma suggests that decreasing temperature and increasing continental land area are associated with increasing maximum body size. The former correlation would be consistent with Bergmann's rule,[15] and might be related to the thermoregulatory advantage of large body mass in cool climates,[11] better ability of larger organisms to cope with seasonality in food supply,[15] or other factors;[15] the latter correlation could be explained in terms of range and resource limitations.[11] However, the two parameters are interrelated (due to sea level drops accompanying increased glaciation), making the driver of the trends in maximum size more difficult to identify.[11] > > > It's amazing how many over-sized versions of commonly known animals have existed at one point in earths history. For your world I would suggest you simply adapt some of the reasons given for the existence of real life megafauna, there's a lot written about this subject. [Answer] Well, first let's go with how it could appear: funny enough, a creature similar to what you wish, although much smaller, has already walked on our planet. [Arthropleura](http://www.prehistoric-wildlife.com/species/a/arthropleura.html) is an extinct species of arthropod that could grow to lengths over 2 meters long. This giant myriapod most likely had an herbivorous diet, and it's ability to grow so large is assumed to be related to the high oxygen concentration in the air and the high humidity of its habitat, which prevented it from dehydrating, as well as a lack of predators, evidenced by its relatively thin exoskeleton. Now, we need to create the suitable conditions for a creature like arthropleura, but bigger and preferably faster. First things first: oxygen. The problems regarding giant arthropods in this site might be second only to the ones regarding the existence of dragons. Their trachea severely limit their ability to obtain enough oxygen at large sizes, their body plan isn't suitable for carrying large weights, their exoskeletons become too heavy, and many others. By this we can already see some issues with our giant centipede coming to life as just an enlarged centipede. First things first, this thing will need a fuel source, preferably one that doesn't need to be at concentrations that could kill everything else. In here magic/mana might be a good substitute, as its usually high concentrations in the environment could likely be used to fuel the creature's body in place of only oxygen (something that is usually used to explain why we have enormous creatures that seem as active as a cat when you want to sleep: mana is being used in addition to oxygen to fuel their bodies, leaving heat as the main issue that's usually ignored). Changing the respiratory system to be something closer to lungs (as well as solving their problems regarding susceptibility to dehydration) also seems like a better strategy. Second, the body plan: we'll need to alter its body a bit so that unlike a giant arthropod, this thing can survive growing up to large sizes. At this point, something of a hybrid between an arthropod and a vertebrate seems like the best option, and [this question's answer](https://worldbuilding.stackexchange.com/questions/57348/maximum-size-of-an-exoskeletal-creature/57398#57398) seems to agree with me in a way. Rather than a straight up arthropod, your creature could be the world's strangest ""vertebrate"", working with a sort of endoskeleton to allow better weight bearing capacity, as well as an exoskeleton as seen in echinoderms, which will grow with the animal and eradicate the issues related with the risky molting processes, which can fail and leaves the animal temporarily defenseless. The legs too would likely be slightly angled In order to go predominantly under the body, as to better support weight (however with many legs and an endoskeleton, I think we can still have legs that come somewhat out of the sides of the body). Changing the exoskeleton structure might also be a good strategy, maybe using keratin instead of chitin. Lastly, the environment: putting apart how unlikely it would be for all of those changes to evolve naturally on an arthropod from earth, your centipede creature will need an environment with little competition, if you want it to be carnivorous, or little problems regarding predators, if you want it to be herbivorous (/lame). In either case, the pressures will likely be similar to what we saw with dinosaurs: prey grows bigger, predators either group up or become bigger too (by become I mean the trait is selected, not that they try very hard to grow like Lammark would likely say), so either your centipede creature saw the need to grow to avoid predation, or it's usual prey started growing up, leaving it to follow the same path. Another approach to the carnivorous growth could be something like we saw with birds and pterosaurs, in which a new predator appeared and outcompeted it with its usual prey, selecting the larger centipedes which could hunt larger prey. Either way, we ended up with 2 potential scenarios: 1- an environment in which the centipedes grew to massive sizes, and much like some of our world's sauropods, they lack predators capable of hunting them once they reach adulthood (this creature is closer to modern millipedes in behavior). 2- an environment in which few creatures are safe, as the giant centipede, with its multiple powerful limbs capable of effortless pursuit through harsh terrain, as well as some tree climbing capabilities due to its sheer size and strength can hunt most of the creatures in its environment, using its modified forcipules and powerful venom to quickly dispatch prey. Thank to its various adaptations that allowed it to grow to large sizes without making it into a slow giant, it was able to become a top nocturnal predator in its environment, usually hunting alone and being relatively aggressive towards other members of its species (this creature is likely closer to the scolopendra genus of centipedes in terms of behavior and overall hunting). In scenario 1, you'll likely have a mount that is rather slow, as it didn't need to outrun any predators due to its size. It will likely be as docile as a modern millipede and it's herbivorous diet shouldn't pose problems and it shouldn't be a problem regarding transportation and carrying goods. In scenario 2, you'll have a mount that works as a natural bandit repellent. It will likely be a naturally agressive mount (more than a lion resting in the sun but likely not as hateful as a scolopendra chasing you). It's diet will be a bit of a problem, since it will require a good amount of meat to be kept in a calmer state (scolopendra already prey on mammals so likely you won't need to feed giant bugs to your centipede). The use of a special muzzle will likely be advised, as well as dealing with the antennae (centipedes rely a lot on smelling to find prey, rather than eyesight, an I'm assuming your centipede has s similar strategy). It will most likely be strong enough to transport people and goods without issues and at a faster pace than its herbivorous counterpart, with its aggression, diet and nocturnal nature likely being your main issues, which could be slightly solved by selective breeding centipedes which are more docile and active during daytime (you likely don't want to trap 3 of these in a barn at night without restraining them until you've successfully selected these traits, or you might wake up to find only 1 left). So summing up a centipede mount will likely be very useful, with its ability to cross various terrain at decently fast speeds, as well as how some species of centipede can climb structures, speed may vary depending on whether the animal was selected just to be big or fast as well, and their overall behavior and levels of aggression will most likely depend on their diet and lifestyle. [Answer] This is fantasy, so lets go with (mainly) advantages. * As noted by others, high speed and a very smooth ride * Large number of claws means it can latch on to any surface and cross gaps. (I know physics, but this is fantasy). So you can ride it right off a cliff and down the cliff face - or across the ditch and over the castle walls and the defenders are still goggling when your mount bites their head off * not necessarily too bright, so they may require close control at all times. Make sure it is very well tethered when not in use * can get through extremely narrow cracks and crevices -- obviously not while rider is mounted, so watch out when your mount decides to take a route that could give you a headache * high rate of reproduction means that, unlike horses, you could raise vast fleets of them very rapidly [Answer] A centipede, or other long multilegged creature, would be quite useful at transporting many people or lots of goods at once, as they would effectively be a camel train with a single body and head. They could also be easy to lead and direct, as their antennae, if they were made less flexible, could be pulled on to simulate an obstacle, making them turn ]
[Question] [ For reasons that are too complicated to explain right now, I'm currently living on the edges of a late Bronze Age/early Iron Age set of civilisations, and I need to make a long overland journey. The world is currently in a pangaea-esque supercontinent; Civilisation, such as there is and what there is of it, is concentrated into clumps here and there, often around rivers, mines, lakes, etc. Starting from a Western European type culture, I need to travel from the west coast to the east, a journey of around four thousand miles or so, with one adult, two children, and a dog. I'll be 'village hopping', hiking or boating from one patch of civilisation to the next, and I'll need to cross various physical barriers like forests, low mountains, probably the odd desert or two... What should I pack for my journey? Assume that I'm carrying a few valuables for trade so I can resupply at villages every few weeks, so I don't need to carry food for the whole trip all at once. What tools and weapons would I have with me? What medical supplies would I have access to? How much could the children carry? And perhaps the most important question, how would I make fire? I don't have flint and steel, because steel hasn't been invented; would I use a fire bow, or carry an ember with me? [Answer] For starters, look at the historical precedent: [Ötzi](https://en.wikipedia.org/wiki/%C3%96tzi#Tools_and_equipment). Weapons, tools, some food. One survival memnonic is Cutting, Combustion, Cover, Containers, Cordage. * Probably several knives and an axe for your use. The knives may be stone rather than bronze for cost reasons, and also so that you don't have to show valuable gear in view of strangers. Perhaps a bow or a sling for hunting, depends on how the various societies react to armed strangers. A sling would be easier to hide. * For firemaking, take both options if you can. An ember in a clay pot, to save you time as you make camp, and firemaking tools in case it goes out. The question would be if you can carry the pot safely. * Tanned leather cloaks and perhaps even a shelter cover. * Packing frames with baskets and clay or leather containers. * Twine and leather cords to keep it all together, and for repairs. * For trade, bronze tools. A couple pounds of axe blades should be worth enough to pay for the food, if you can get a decent exchange rate. Perhaps amber and furs. Regarding what the children can carry, depends on their age and health, and how much speed you expect them to make. 10 or 20 percent of their body weight? Are those 4,000 miles the direct line or the effective distance? I would not count on more than 10 miles per day, so you might have to build winter quarters several times on the journey. Do it early enough to forage and hunt if there are no villages with enough surplus to feed you. [Answer] Consider this an addendum to @om's excellent answer. Your family should carry all of the necessities which that answer identified. These are just a few luxuries to make the journey safer and more comfortable. If your "Western European" type culture has developed musical instruments, being able to "perform for your supper" can reduce the amount of food which you either need to carry or forage for. Talent with such instruments might also get you past the outer gate of the more xenophobic walled villages. Similarly, drawing/painting supplies and the artistic talent to use them can be traded for warm accommodations and food for the winter. Complimentary portraits of the tribal chief and each of his children could be traded for safe passage across his territory. Serving a purpose helps you avoid being seen as a threat. Information is going to be your most useful possession. More valuable than the tools for creating fire is the knowledge of how to create such tools. Imagine the journeyman trader who can take dry wood and raw iron and some of that worthless flint rock, and create a magical spark making tool. She would be welcome everywhere. [Answer] A lot of what you should pack with you is based on what you know about your environment. It is not a matter of what technology you have available, but what is your level of awareness about disease, chemistry, human psychology etc. I am assuming a modern understanding of the environment, with iron age technology. # Medical Supplies * Snakebite treatment kit. Includes herbs and potions. * Small tweezers for pulling out thorns, spikes etc and a sharp scalpel for cleaning festering wounds. * Bandages for wrapping on wounds. Each person ought to carry their own medical kit. It would easily fit in a medium sized buckskin pouch, that can be hung from the waist. # Weapons The weapons would be used both for hunting and for defense against hostiles. * 4 knives. Adults carry large knives (cutlasses), one made of obsidian, for skinning game and other bronze for chopping dry twigs for fire. Children carry one small knife (the size of kitchen knives we use these days). Both made of stone, primarily for defending against hostiles. * Two bows. One large, as primary long range weapon against hostiles and for hunting large game animals. Smaller bow for hunting smaller game (squirrels, hares and snakes). Bows are carried by the adults while quivers/arrows are carried by the children, considering the children are aged 8 or above. * Two blowpipes. 4 feet each. For hunting birds. Blowpipes would be hung by the children's back while their darts would be carried in the quivers with arrows. * A pouch of poison for applying on arrow and dart tips. The pouch would be carried by one of the adults. # Food Supply While it is understood that you cannot carry all the food for your journey with you and that with your weapons you can easily hunt game ranging from deer to birds, you would want to make sure you don't starve in case you are unable to hunt anything for a few days. Every time you are in a region with easy game (lots of ducks/turkeys/squirrels/hares/deer), you would want to hunt as many as you can carry, and smoke or sun-dry their meat for future consumption. While you might get lucky and bring down a bear with a well placed poison arrow shot to the neck or eye, I would strongly advise against it. There would be much greater chances of you getting killed in the effort instead, and you would not be able to carry all the meat with you, either. Your dog is going to be a major help for you in tracking large animals you have successfully hit, and in retrieving birds you managed to shoot. In places of shallow water, you would want to hunt small fish or water fowl. You would also want to forage for berries and edible roots and tubers when you find them. Seasonal fruits such as wild avocados, pineapples and apples would also be a big help. In case you are able to exchange some valuable item (whichever you might be carrying for trade sake) for food, I would suggest getting corn or molasses in return. Molasses is essentially sugar and can be used in hard times. Corn is great for drying up and roasting in small quantities on nights when you don't find any game. Considering that you have mentioned deserts in your journey, I would strongly advise carrying your water with you for desert parts. That would mean thoroughly washing a deer or goat's bladder, tightly tying up one end of it, filling it with water and then tying up the other end. Everyone would need to carry one such bladder with them for desert walks. Remember, you would also need to carry water for your dog, too. # Clothing And Shelter 4000 miles is not a small distance and on foot, with children, you would hardly be making more than 10 miles each day. This would mean no less than 400 days for the whole journey. And then there would be rain and snow, too. Of course you are going to need warm clothing and some supplies for building a shelter. Your regular buckskin/wolfskin coats and loin clothes will do for most of the time. But in winter you are going to need something thicker and warmer. That is going to be either a full (head to ankles) length of a wolfskin coat, made from skins of two or more wolves. Another option would be bearskin coats. These would be warmer and heavier and would also provide protection during snow. However, as mentioned above, bears would be next to impossible to hunt with your 2-people team even with poison tipped arrows. This means you would have to get them from some village, in return of some valuables such as wild game or metallic objects (such as axe-blades). Once the winter season is over, you can trade your bearskins back to some other village in return of supplies you need, so that you don't have to carry unnecessary warm clothing during summer time. Sometimes you might need to stay in one place for a week or so. That would occur when there is a heavy rain lasting more than a day, resulting in boggy places and seasonal streams everywhere. You might also have to stop travelling in case one of your family members gets sick/injured and is unable to travel. In such times you would need to build a small hut or tent for your family. This would include chopping down wooden sticks and building a small hut with clay and sticks. It would take a day to raise such a hut if all of you work on it. # Fire This is going to be the hardest of all. Since you don't know how to make fire from flints. You would have to carry a lit torch with you all the time. Amazingly enough, buying fire from a village might cost you valuables, even if it is burning in every hut. I would certainly advise carrying your fire with you. In places where you find oil wells, make sure to dip your torch in it, as it would burn longer with the crude oil applied on it. [Answer] You also might want to look at what nomadic cultures do since that is probably closer to what a family traveling would be like. They might want a pack animal, and would definitely need to be able to hunt, they will never be able to carry enough goods to buy everything along the way. you will probably see travel as move for several days find a nice spot resupply and fatten up for a week or so then start traveling again. They will probably spend very little time in cities or towns as that costs money or requires connections. Now if any of them have special skills as entertainers or craftsmen they might be able to make money along the way more easily and would gravitate to populations centers more often. Many if not most skilled craftsmen were nomadic during the bronze age, few communities could support their services permanently. In which case you see travel from community to community spending several days/weeks at each community providing their service before moving on. [Answer] ## Fire Production Bronze age technologies for fire can include: * [Friction](https://en.wikipedia.org/wiki/Firelighting#Friction): Hand drill and bow drill * [Percussion](https://en.wikipedia.org/wiki/Firelighting#Percussion): Flint or quartz onto stone containing iron, such as pyrite or marcasite * Lens: Made of [glass](https://en.wikipedia.org/wiki/History_of_glass#Origins) or [ice](http://www.instructables.com/id/Making-Fire-With-Ice!/). If ice is used, a lens mould would be extremely useful to have * [Fire piston](https://en.wikipedia.org/wiki/Fire_piston): Here is a [video](https://m.youtube.com/watch?v=SkWJdWGdgaM) detailing how to make one ## Food Supplies In addition to the other answers, the [Nation Outdoor Leadership School](http://www.nols.edu) (NOLS) has researched food supplies extensively. Here are some of their recommendations: ## Dietary Needs Depend on Degree of Activity * Average Wilderness Activities (Backpacking, Kayaking) 1.5 - 2 lbs of food per day 2,500 - 3,000 calories per day * Strenuous Wilderness Activites (Hiking & Camping in Snow) 2 - 2.25 lbs food per day 3,000 - 3,700 calories per day * Very Strenuous Activities (Extreme Mountaineering) 2.25 - 2.5 lbs food per day 3,700 - 4,500 calories per day ## Food Type Percentages NOLS also recommend the following percentages of types of food: * 18% dinner foods * 16% breakfast foods * 21% trail foods * 13% cheese * 14% milk, eggs, margarine, cocoa * 7% flour and baking * 7% sugar and fruit drinks * 4% soups, bases, deserts (Source: [The National Outdoor Leadership School's Wilderness Guide by Mark Harvey (1999)](http://rads.stackoverflow.com/amzn/click/0684859092)) The ramifications of this is your group will need to resupply more often when involved in physically demanding activity like climbing, because they can only carry so much weight, but will be eating more pounds of food per day. But, with light activity such as plains hiking, they can go for longer between resupplying. I'm not sure how you can adapt all that to a bronze age diet, but that's at least what modern nutritionists recommend. ## Food Availability Depending on where your party is will greatly effect what types of foods can be scavenged along the way. I personally spent 1 month in the [NOLS Wind River Wilderness](http://www.nols.edu/courses/wind-river-wilderness/) course in Wyoming. I had been studying edible plants (including mushrooms) for years ahead of time as a hobby, so I was looking forward to putting my foraging skills to good use while camping. I was amazed at just how inhospitable the Wyoming wilderness is in terms of edible plants. I think in the entire 1 month of hiking, we managed to make 1 very meager salad when we found a patch of edible leafy plants, and also 1 batch of cooked puffball mushrooms. That proved to me the stark reality of trying to feed myself by foraging plants--if you are not in a naturally fecund area, you will very likely not be able to get enough calories per day to survive. Nuts, berries and other edibles with significant calories and nutrition are very, very rare in most areas. So, hunting animals would have to be the only real scavenging method for feeding your group in a temperate land like North America. I also did a research paper on pioneer living in early America and was amazed to learn that trappers who ventured into wilderness areas would take all parts of the animal (except fur, teeth, bones, etc.) and cook them all together in a pot and eat all of it! I previously had never thought of eating all the organs, but apparently they did. I suppose if you are hungry enough, every bit of food becomes attractive. ## Pack Animals Given the average distances between modern towns, geographies and general lack of food availability in the wild, mules or other pack animals that could graze for their own food could provide your group with an essential means of carrying enough food and shelter items to make a successful, long journey practical. ## The Long Walk All that being said, you might be interested in reading [The Long Walk](http://rads.stackoverflow.com/amzn/click/149302261X), the memoir by former Polish prisoner of war [Sławomir Rawicz](https://en.wikipedia.org/wiki/S%C5%82awomir_Rawicz) who escaped from a Soviet Gulag and walked 4,000 miles to freedom in World War II. The movie [The Way Back](https://en.wikipedia.org/wiki/The_Way_Back) is based on this book, and is available on Netflix. I haven't seen the movie or read the book, but since it is a real life account of a journey quite like the one you're describing, you might find some useful unexpected ideas there. [Answer] Supplementary answer: poultry and hawks Poultry are a very good way of converting stuff that you can't eat into stuff that you can (eggs, chickenmeat). If you have a beast of burden they are fairly easy to transport from camp-site to camp-site in small cages or even just with wings bound and dangled by their legs. Live meat keeps a lot better than dead meat. Obviously the terrain has to be fertile enough for hens to forage from if you want to keep them indefinitely. Here on Earth it's not known how long ago the domesticated Burmese jungle fowl (or hen) was traded across Asia all the way to Europe. At the dawn of written history, hens were onmipresent. It didn't take long for them to be everywhere in the Americas as well, once we introduced them. A trained hawk is a huge asset in arid terrain that cannot support hens, if your culture has invented falconry. It can hunt desert or grassland creatures that you probably couldn't hunt yourself. [Answer] I would say you are in a bit of a pickle. Your team is way too small. In that age most men carried weapons at all times, for a reason. There was no police, and there would be no revenge for killing a stranger (if you were local, your family would revenge you) Pack around the idea of travelling discreetly. No fire unless you have. Hide valuables (except a few so that any would-be robbers are satisfied). Only stop in larger cities where you are less likely to get killed. Try to travel with a large caravan as servants (and then you might not need to bring much). Arm the kids. ]
[Question] [ While researching unique methods of nuclear energy generation and propulsion, I encountered many things, both in rocketry and aerospace. For instance, the nuclear thermal jet engine. However, I found the thermal intermediary of most nuclear energy applications annoying and lacklustre when it came to small scale applications and power density, and direct conversion methods such as PIDEC or fission fragment to be... lacking outside of space. I came up a potential solution. In a model akin to a normal internal combustion, it is a NUCLEAR piston driven engine that provides direct shaft power. The cylinder is made of a neutron moderator-reflector, with the 'fuel' being highly enriched uranium or plutonium hexafluoride (gaseous state). You could probably add some helium for better heat transfer. The 'spark plug' is a neutron source. A piston compresses the UF6 gas where it then goes supercritical, rapidly expanding and driving the piston with direct mechanical power. I imagine this system has greater power to weight ratios than nuclear-thermal energy, meaning it has better small-scale applications such as ships. Some issues that could present themselves is the fluorine that occurs following each stroke, meaning cycles would have to include 'washes' to prevent internal corrosion. How possible is this system? [Answer] Possible? Sure. Efficient? I can't imagine so. When you're introducing things like washes, you're adding a lot of thermodynamic overhead in addition to mechanical wear/stress. You'd also need a way to cool the contents of the piston, because otherwise you get one powerstroke and then the system is at equilibrium and doesn't reset, so you're also exhausting gasseous nuclear fuel which isn't a great look for your product. And after all of that, you're still limited to the same Carnot efficiency that a basic steam piston would be. [Answer] Frame flip: Instead of fission with Uranium, consider fusion. [General Fusion](https://generalfusion.com/) is a company working on a novel fusion reactor design. They begin with a blob of molten lead. At the top and bottom are injectors that produce "smoke rings" of plasma. The lead is spun by pumping it in at the side at an angle. This opens a vertical hole. The plasma is injected in a smoke ring so that the ions are rotating such as to produce a magnetic field. It's like a Tokamak without the Tokamak. One puff of plasma from the top and another from the bottom. When they hit they reinforce. At exactly the correct time, all the pistons around the outside are fired. This produces a shockwave in the lead, collapsing the central hole. The compression brings the plasma to fusion temperature and density, producing a pulse of fusion. The lead absorbs the energy from the pulse and carries it out to the heat exchangers. From there it is a fairly normal power plant. The reason the lead can compress the plasma is because the magnetic field in the plasma induces a counter current in the lead as it is compressed. This tends to keep the plasma together. This process was discovered in the 1970s, and made to work with explosives. However, research into it was cut off due to nuclear proliferation concerns. After all, if it were pushed in the wrong direction, it might become a nuclear enhanced explosion. The pistons achieve the accuracy required in a keen way. There is a laser range-finder on each piston that detects exactly where it is. And there is a small electromagnetic brake on each piston, controlled by a computer, to slow the piston to the exact required speed. This degree of accuracy has already been achieved. They are by no means done with challenges on this design. But if they make it work, the plan is one pulse per second, each pulse producing about 100 mega-Joules of energy. That means a thermal output of about 100 MW. It isn't exactly an engine since the pistons don't get driven by the fusion. And the smallest vehicle you are likely to mount such a thing in is an aircraft carrier. But hey, it's a steam-punk fusion reactor. [![enter image description here](https://i.stack.imgur.com/Qpizo.jpg)](https://i.stack.imgur.com/Qpizo.jpg) [Answer] It is not only possible but it ran cars ("Volga-Atom") in the Soviet Union. [![Volga Atom](https://i.stack.imgur.com/D3N9j.jpg)](https://i.stack.imgur.com/D3N9j.jpg) The first one describes uranium piston and helium gas engine. The second one describes piston-based engine with UF6 inside. (automatic translation) > > After six months of settings and experiments, the engine installed on the stand worked for three months completely normally, while the conditional mileage was about 70,000 km. It was time to put it to the test. Engineers of a specially created working group of the Gorky Automobile Plant (GAZ) were involved in the design of the chassis. The task set surprised them a lot. The suspension had to be significantly strengthened: the A23 weighed not 200 kg, like the regular GAZ-21 engine, but almost 500. At the same time, the engine had absolutely fantastic characteristics at that time: 320 hp power. and a torque of more than 800 Nm at low RPM (60 rpm). The requirements also stipulated the complete exclusion of access under the hood, the absence of a fuel system and attachments, and especially the presence of a productive cooling system. > > > In April 1965, the car went to the test site near Seversk. According to the memoirs of Valentin Semenov, who took part in the development of the engine, who managed to drive a car (or an atomobile?), the sensations were very unusual: the car was very heavy, but the engine power compensated for the increased weight. Acceleration was brisk, but braking was worse. And the engine was also very hot, and in the car, despite the Siberian cool spring, it was very hot. > The tests carried out showed that the design is quite working, while the real mileage resource was more than 60,000 km. > > > [![Volga-Atom hits the road](https://i.stack.imgur.com/JVyCE.jpg)](https://i.stack.imgur.com/JVyCE.jpg) It never got [past prototyping stage](https://back-in-ussr.com/2018/04/sovetskiy-atomnyy-avtomobil.html), but it got the car around for some mileage. Update: Looks like the prototype is April Fools. You can still use the concept, though. [Answer] ## No, this is not going to work. You've missed the difficultly of reaching critical mass by using compressed UF6 gas. First, you have interspersed a bunch of fluorine in the middle of your reaction mass. This alone will increase the average atomic difference considerably, which is terrible for your purpose. And you converted your fuel to a gas. Your average atomic distance just went up massively. You will not be able to overcome this by injecting neutrons - there is no way to control enough neutrons sufficient to support a massive injection rate at the time of the spark, and turn it off at other times in the power cycle. In the reaction chamber won't be able to play the neutron reflector card to make a real difference either. If you want a nuclear bang to power your engine, you will have to use solid fuel nuclear core bombs and feed them into the chamber for each power stroke. I.e., you now have a nuclear pulse ICE instead of a nuclear pulse rocket. --- @BillOnne - toolforger is correct, and I should have made that point clearer. It is also a very non-linear relationship. IIRC, the implosion in a PU-239 bomb only makes the fuel about 10% denser, but this is key to its function. Never considered including a moderator as part of your fuel source in a bomb - and not qualified to do so, but since no bomb uses this approach (as far as unclassified info reveals), I have no reason to believe it is significantly beneficial to the process. I did a little research to confirm that use of a moderator does not benefit nuclear explosion. This is taken from the notes in the [Los Alamos Primer](http://extremal-mechanics.org/wp-content/uploads/2012/09/Primer.pdf). > > Slow neutrons cannot play an essential role in an explosion process > since they require about a microsecond to be slowed down in hydrogenic > materials and the explosion is all over before they are slowed down. > > > Slow neutrons, a.k.a. thermal spectrum neutrons, are those that have been slowed down by the moderator. This is useful in a nuclear reactor because it increases the cross-sectional area of the fuel - which makes it significantly more likely to trigger a fission reaction before the free neutron escapes the fuel source. I mentioned in a comment that critical mass is not linear with fuel density. As a first order approximation, critical mass is proportional the 1 over density squared. The reason Pu-239 requires an implosion to make a bomb is that all plutonium is poisoned by the presence of Pu-240 - an artifact of making plutonium in a reactor. The Pu-240 fissions more readily and a simple bullet plug bomb will make a fizzle explosion before the supercritical plutonium has a chance to involve the bulk of the Pu-239 in the explosion. I did not mean to imply that you could not make a critical mass of plutonium without compression, just that the sub-critical mass is converted into a critical mass by the implosion even though the compression effect is relatively minor. [Answer] This is kind of a frame challenge, but we have researched ways to turn nuclear energy into motive energy and they generally don't rely on engine-like devices. Pistons, though, that we like. First off, containing a nuclear explosion is going to be a really hard problem from a materials perspective. Your "combustion chamber" either needs to be gigantic, or it needs to be made out of unobtanium - there's very few materials that can survive repeated nuclear blasts, and none that can do so at close range. So, we went with making the combustion chamber gigantic. That led to [Project Orion](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) - essentially, just create the piston part of your engine, then put an entire spaceship on top of it. Toss nuclear bombs out the back, blow them up, and ride the shockwave. The "combustion chamber", in this case, is "all of space". Sure, you're losing a lot of energy, but it's not like you can feasibly harvest the rest of it anyway. But what if instead of a nuclear internal combustion engine (pfft that's technology from the 1700's!) we went with a nuclear turbine? (also a technology from the 1700's) Turbines work well because they don't actually need a full on explosion, just a continual burn. This sidesteps a lot of our issues and seems really feasible! Well, that train of thought gets you [nuclear powered aircraft](https://en.wikipedia.org/wiki/Nuclear-powered_aircraft), though there's nothing in principle keeping you from mounting the turbine on a car or whatever - the only reason why they planned on putting these things in the sky is because of the horrible trail of radiation poisoning they leave behind, which nobody wanted at ground level. The basic idea is you run a reactor exposed to the atmosphere, and then force air into it [like a ramjet](https://en.wikipedia.org/wiki/Ramjet). The heat from the reactor makes the turbine go without using any other fuel, and also leaves a nice radioactive trail because, again, you are running a reactor exposed to the atmosphere and forcing air into it. So yeah, those are the two ways our wacky scientists back in the 60's figured out how to turn nuclear power into go juice. These days we just use nuclear power to charge battery driven vehicles, which works better for everyone in the near vicinity. [Answer] In addition to the technical challenges others have mentioned, there's what's known in fusion as the "[First Wall Problem](https://www.science.org/content/article/how-line-thermonuclear-reactor)". Essentially, you're facing a high-temperature, highly-corrosive, high-pressure gas that has a tendency to ablate and/or chemically remake and/or atomically remake everything it comes in contact with. You're dealing with fission rather than fusion, but many of the issues are going to be closely related: * neutrons embedding in the wall material will change the elemental composition of the wall, corroding it. * High fluxes of Uranium and Flourine ions (and stray electrons & gamma rays) are going to chemically corrode the wall. * Heat is going to tend to melt the wall in places (or spot-weld joints). * Material ablated off the wall is going to pollute the gas / plasma you're using as fuel, making the compression and reactivity less efficient. * Material ablated off the wall is going to re-condense in the exhaust, possibly blocking and/or corroding downstream systems. That being said, this is one of the coolest awful ideas I've heard since the [Orion nuclear rocket](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)), which consumed nuclear bombs by the hundreds to send aircraft-carrier-scale payloads to Mars and back... [Answer] This answer is about doing it as a fission system. The OP mentions Uranium. As you describe it, there are huge challenges. There are two basic time scales to nuclear fission. The slow one is critical but not prompt. And the fast one is prompt. Prompt has a doubling time of a few microseconds, possibly faster depending on the design. That means you can't usefully control the energy output. Any engine is going to have RPM in the few thousand at most. It cannot respond to the power changes. Your machine explodes on the first stroke. Early in the power part of the first stroke. Critical but not prompt has a doubling time in the milli-second or slower range, again depending on the design. You might hope to make this useful. The difference between prompt and not-prompt is not large. Power reactors are carefully designed to stay in the not-prompt range, and for it to be difficult to get across that threshold. Chernobyl was an example of passing over to prompt, and that only for a very short time, some few milliseconds. That was long enough to heat the coolant water enough to produce a steam explosion that destroyed the station. Controlling power through compressing the fuel would be a finicky thing. An extra 1% compression would be more than enough to push you over. A tiny errror in the input fuel pressure or composition and your engine disappears. There are other problems. To complete the cycle you either have to cool the fuel in place, or pump it out and cool it outside. For you to cool it in place is tough. I am unaware of any engine that cools the fuel in place. When the fission stops the decay heat is round about 5% of the full power value. After 1 minute it is down to about 1%. These values depend on the design but they are reasonable approxes. So you need to cool your fuel in a useful time, while dealing with the decay heat. In order to get the heat out in a reasonable time you might well require a cooling system that consumed more energy than produced in the pulse. If you were prepared to have an hour between strokes you might get something. It seems mighty inefficient. To pump it out you have to keep in mind that only a minute fraction of the total energy is released in one cycle. So you would need to cycle the fuel through the engine many thousands of times. (100's of thousands? Depends on the design.) You would need a system that is capable of pumping out the gas and pumping in the previously cooled gas. But note that 5% decay heat. Your pumping system has to deal with 5% of the total power coming out as mostly radiation. And it will be cooking everything near the exhaust port of your engine. Plus you need to remove the fission products. These are usually quite radioactive. Some of them are gas. And several of them are challenges at handling, such as the Tritium that likes to leak through stuff. These are issues that are being solved for molten salt reactors, but using systems that weigh 100s of tonnes. And that cycle the fuel every few hours, not on a cycle of once-per-engine-stroke. It gives a lot of the nastier isotopes time to decay while still in the reactor. So your working fuel is going to be this tiny fraction of total fuel. The rest of the system will be a 100's of tonnes station that will tend to leak radioactive isotopes at a prodigious rate. And it will have a very tough time avoiding exploding. And there are already nuclear power station designs on that scale that work far better in every way. [Answer] I believe the problem would be “knocking”. In an engine with a spark plug to ignite the fuel in the chamber there is a condition where the engine could run too hot and the fuel ignites from the heat before the spark plug fires, and that leads to a rough running engine and lost power. A similar condition is likely in a fission powered piston engine where a stray neutron from a spontaneous fission sets off the fission too soon and you lose power. I can imagine how such an engine might work in theory but in practice I can imagine a spontaneous fission causing timing problems on the “detonation”. I doubt a fission explosion is required to make it work, it just needs to get hot after compression and then have a cooling off cycle somewhere. The “spark plug” could be something like a proton gun or a small fusion device, whatever would be a reliable and controllable neutron source, but the uranium fuel and fission products could trigger the critical condition too early with a spontaneous neutron. If put in a continuous critical fission state for heat, like some kind of rocket or turbine, then the issue of early (or late) fission is not an issue. With enough fission events going on the statistical timing of these events becomes a smooth curve that can be calculated out and put into the design. There’s no need to know when each critical event happens, there is just one continuous critical state. Just keep the hot ball of gas in the right spot and the engine keeps running smoothly. Knocking, that’s the problem I see in a piston nuclear fission engine. Maybe with the right neutron absorbers the knocking goes away but then you are throwing away a lot of valuable neutrons you could have used for fission somehow. With neutrons having no charge they can’t be funneled into an adjacent piston easily, or stored in a cyclotron (or whatever they are called). I like the theory. I’m just thinking knocking will kill the idea in practice. Edit to add: I was talking about this hypothetical engine with my brother and he mentioned something to the effect of combustion engines being able to use valves to release pressure, potentially a simple means to prevent knocking in an engine. So the solution to the problem is likely much simpler than I considered initially. This still leaves the issue of fuel being burned and not turned into useful heat, instead the pressure from the heat is vented out the exhaust. Perhaps the lost heat is trivial but over time that would likely count against the idea with other engines that aren’t “burping” excess waste heat out of the exhaust with every premature detonation. Delay things somehow to prevent premature detonation and that’s also lost efficiency because the power stroke was shortened. I believe this can be made to work, it’s just going to have efficiency problems. [Answer] I've given this some thought since the other day when I commented. There are several almost insurmountable issues with such a concept. First, just how large are you willing to allow this IFE (internal fission engine?) to be? Project Orion had variations that could launch from the surface, and these tended towards being huge. The pusher plate that prevents the occupants and their vessel from being vaporized is several feet thick, and made of steel (or perhaps some weird iron alloy designed to be slightly more robust). Even then, while it protects the occupants from being pulverized by mechanical damage or burnt down to carbon, it's not exactly something it'd be safe for you to lick like in some dumb Tiktok challenge video. If this is a mechanical engine with pistons, this isn't for an aircraft carrier, it's for those giant mobile cities in that bad Mortal Engines movie. Something on that scale. Seriously... it is difficult to imagine something large enough to bother moving with such a motor. Then there's the issue of just how often the thing can fire these off. Project Orion had different pulse timings depending on whether we're talking about launching from the surface, or if it was cruising in deep space, but at most you're talking about 1/s. I'm not sure that can work for a piston engine. Then there's the issue of stroke length. The pistons in your car move only inches, the pistons in a large ocean-going vessel's diesel engine move only feet. Can even a small, sub-kiloton explosion move this fewer than hundreds of feet? If you try for a shorter stroke, doesn't the nuclear fireball just melt the piston and the walls of the cylinder? And about that... Orion's pusher plate only survives in solid form because mere millionths of a second later it is hurling itself away from the epicenter of hell. The cylinder walls do not have this luxury. The piston? I think it survives much like the pusher plate, but the cylinder itself does not. And while it won't melt all the way through, my limited understanding of automotive mechanics is that you want the cylinders to remain in their solid state (instead of, you know, skipping liquid and gas and going straight for plasma). This part almost requires exotic matter to work... something that can put up with alot of bullshit. Think neutron-degenerate matter, but maybe not that particular sort of exotic matter (you're already talking about playing with neutrons after all). But, if you can overcome the problems of: having something large enough to move, the absurd engine geometries involved, and the materials science of something that can survive constant nuclear detonations and remain mechanically sound... well, it sounds like it will take at least the entire 180 minutes for the comic book superheroes to save the world from you. Even then it will be tight, they might have to montage it. Also, thanks for giving the world the concept of tera-horsepower. No one knew that unit existed until yesterday. [Answer] I recall a free piston Sterling cycle nuke design intended for electrical generation on the moon or similar, the free piston design had the advantage that the whole thing could be hermetic allowing the use of helium as a working fluid. The elephant in the room for ANY nuclear plant better then simple nuclear thermal is the usual one of the Carnot limit and being able to dump the waste heat, space may be cold, but it is one hell of a good insulator. [Answer] A lot of the other answers here are trying to suggest something equivalent with a modern car engine, but there are a lot of problems with this concept, as others have covered in their answers. But you can make this work if you look at older technologies. Think steam engines, like in the old trains. Those would have a big tank full of water, that you heat up and the resulting steam would push the pistons inside the cylinder. Incidentally this is very similar to how the current nuclear power plants work... The nuclear reaction heats up the water used to cool it down and turn it to steam which is then used to spin a turbine that spins an electric generator. Replace the turbine with a piston and you have your nuclear powered piston engine. Obviously this will be a huge engine, so it would not go in your car, but you could conceivably install it in a ship, or a fixed building. ]
[Question] [ In a brand baby spanking new world I am building, appropriately named Escargard, punningly named by the AndyD273, mollusks have become the dominant form of life. Resulting in aliens similar to those below [![enter image description here](https://i.stack.imgur.com/YRrHB.jpg)](https://i.stack.imgur.com/YRrHB.jpg) But sadly the longer I thought of such a scenario, the less likely It became, while many mollusks lack the scaling problem that insects face, they have their own. The gelatinous structure of the body of mollusks makes it difficult to rightly scale them. Without editing their biology, what is the largest I can make a mollusk? What changes can I make to mollusk biology to allow them to become massive? [Answer] # Yes, depending on where you draw the line on 'mollusc.' A more accurate term might be 'mollusc-descended.' Any very large land mollusc would almost certainly no longer be invertebrates, since after a certain size, the square-cube law would dictate that their unsupported insides collapse into jelly. Even in the picture you provide, some of the 'molluscs' have legs, which means that they have bones. They would also most likely develop some muscle-analogue to make better use of its new bones. Larger mollusc descendents might resemble animals with integrated shells such as turtles or [ankylosaurs](https://en.wikipedia.org/wiki/Ankylosaurus), and have a mixture of traits from both of them. Their characteristic breathing cavity in their mantle is pretty primitive, so there would likely have to be substantial changes to that in order to make it able to handle larger sizes, unless there was enough oxygen in the atmosphere to make fire a huge hazard (which could provide an interesting reason for most life to remain in the sea, and provide unique challenges for life that elects to stay on land). Sea-based molluscs would have no such restriction due to the support of the water around them, and would be free to assume whatever twisted, nightmarish forms your imagination can devise. Without making any changes to their biology, I doubt you'd be able to make land-based molluscs bigger than human-scale, since that's about where [prehistoric insects](http://www.neonnettle.com/feed/90-8-giant-prehistoric-bugs-that-totally-would-ruin-your-holiday) peaked at. And even that seems a little far-fetched. Squishy invertebrates lacking exoskeletons simply do not scale well without major changes. [Answer] This is a mollusk. [![enter image description here](https://i.stack.imgur.com/ImVoV.jpg)](https://i.stack.imgur.com/ImVoV.jpg) It's [a 7 meter long giant squid preserved in a block of ice](https://en.wikipedia.org/wiki/Giant_squid#/media/File:Giant_squid_melb_aquarium03.jpg). There's an even larger species of mollusk, the [Colossal squid](https://en.wikipedia.org/wiki/Colossal_squid), living in the Antarctic Ocean. It's estimated to be about 13 meters long and weighing in at about 750kg. Its eyeball is a foot wide. Another example of a large mollusk is the [Seven-Arm Octopus](https://en.wikipedia.org/wiki/Seven-arm_octopus) clocking in at 3.5 meters long and weighing about 75 kg, as much as an adult human. If you're wondering where the shell is, [it's on the inside](https://en.wikipedia.org/wiki/Cephalopod#Shell). It seems the trick for a mollusk to get big is to ditch the shell and use it as a supporting structure. Large animals can use their sheer bulk as protection. [Answer] Land dwelling molluscs are possible, but will change their structure considerably in order to function as fully land dwelling creatures. Even amphibious molluscs will need to compromise the features which make them successful aquatic creatures in order to be functional on land. Some things to consider if they are the truly dominant order on the planet is they will have radiated out to fill lots of different niches (as suggested by the diagrams). However, just drawing a creature because it is "cool" isn't really going to explain why it looks the way it does. Consider how terrestrial animals have evolved to fill the various niches, then realize your molluscs will have to create some similar adaptations to fulfill similar roles in the ecosystem. Here are two illustrations from the TV show "The Future is Wild", which postulates squids coming to live on land 200 MY in the future. The "Megasquid" is a huge creature which seems to fill the role of large herbivore, much like an elephant or maybe sauropod dinosaur, so it has grown to an incredible size, some of its limbs have bulked up to support terrestrial locomotion, its gut may have subdivided into multiple stomachs to digest plant matter (or it has a gizzard full of rocks) and so on. [![enter image description here](https://i.stack.imgur.com/eHmoT.png)](https://i.stack.imgur.com/eHmoT.png) [![enter image description here](https://i.stack.imgur.com/TVFS0.png)](https://i.stack.imgur.com/TVFS0.png) Megasquid Another postulated creature is the Squibbon, a tree dwelling creature perhaps analogous to monkeys. It may not look like a monkey, but it has adapted in many similar ways to living in trees, including long grasping limbs, moving the eyes for stereoscopic vision and so on: [![enter image description here](https://i.stack.imgur.com/6wYDL.png)](https://i.stack.imgur.com/6wYDL.png) Squibbon You could do similar thought processes for major predators, small creatures which fulfill the roles of mice, molluscs which have moved back to the sea in the manner of seals or whales and so on. So have fun with this, but think carefully about the ecological role your creature is supposed to fulfill, look at how earthly life has done so (over several eras, there have been giant amphibians, dinosaurs, marsupials and mammals, as well as occasional birds which have all filled similar roles in the ecosystem, so you have lots of examples to look at). [Answer] All you need is a support structure, your mollusks need to evolve a skeleton of some kind for life on land. they already have the tissue to lay down calcium carbonate so you could have a calcium carbonate based skeleton. Mollusks have a closed circulatory system, so unlike insects, their size is really just limited by how they can support themselves. If you really want to keep the shell you could make them essential somehow, maybe in the aliens they provide the rigid space and attachment for the muscles that pull on lungs, and thus it is easier to keep them then evolve a new breathing system. for the aquatic species you are fine, some ammonites got huge while keeping their shell. some believe the shells may have even become buoyancy chambers. And some of the heteromorph ammonite have truly bizarre shapes. honetsly google image search "heteromorph ammonites" there are just so many shapes. [![enter image description here](https://i.stack.imgur.com/Xb16P.jpg)](https://i.stack.imgur.com/Xb16P.jpg) [Answer] Maybe, but they won't look like the ones you've drawn What is a mollusk? It's safe to assume that these creatures aren't actually Mollusks, since that would require that they be descendant from the same common ancestor as Earth-mollusks, so let's go with mollusk like aliens. Let's say that they're all descendant from some mollusk-like ancestor, but that without competition from some tetrapod-like creature, they've gone on to evolve and radiate and occupy most niches that tetrapods have gone on to inhabit on Earth. That's certainly possible, but your final forms probably won't look much like mollusks. Over time, they'll gain adaptations to help them survive in a variety of different land environments, increase in size, move about, see, and do everything else that's useful for large land animals. Eye stalks, for example, are likely to vanish as the animals become more mobile and develop more complex eyes. They're great if you're a snail, since snails can't turn around to see what's behind them, but for a legged, running animal, they offer little advantage, are metabolically costly to grow, and put fairly delicate, difficult to regenerate structures (the eyes) in danger of damage. Shells, similarly, will be lost in any animal that relies on running down its prey, running to escape predators, or that's so big it doesn't need to worry about predators. Mobility, in an environment of relatively immobile creatures, is a huge evolutionary advantage. Early fish, in a similar example, had thick plates of bone armoring their bodies, but these were lost in favor of small scales for the sake of increased mobility. Other adaptations will appear as well. Things like hard shelled eggs, live birth, dry skin, and internal bone-like structures will all appear, allow their bearers to live in dry climates and support their bulk out of water. That being said, while certain niches strongly favor creatures with these types of adaptations, it will almost definitely be the case that there exist other evolutionary niches in which less advanced (and more mollusk-y) creatures can compete easily, or even gain an advantage. Jawed, sluglike creatures with primitive skeletons and tentacles might make for effective amphibious ambush predators, similar to crocodiles on Earth, while snail-like creatures with supportive internal structures and advanced lungs might be perfectly suited to shuffle around in shallow waterways and marshes, mowing through patches of aquatic plants. Just like amphibians on Earth, though, they'll likely be replaced as the dominant creatures on your planet as evolution produces more highly evolved forms that can out compete them in other niches. [Answer] Giant molluscs - particularly cephalopods - are frequent subjects in speculative evolution. Another answer talks about the Megasquid and Squibbon from TFiW, but there are many more I can think of from hobbyist SE projects. For example: The Stalker, a predatory descendant of the cuttlefish: [![enter image description here](https://i.stack.imgur.com/RDMHL.png)](https://i.stack.imgur.com/RDMHL.png) The Desert Hopper, a macropod-like snail: [![enter image description here](https://i.stack.imgur.com/9aehx.jpg)](https://i.stack.imgur.com/9aehx.jpg) Dragonsquids, cephalopods that fly with their lateral flaps: [![enter image description here](https://i.stack.imgur.com/1Rp8b.png)](https://i.stack.imgur.com/1Rp8b.png) Believe me, there's a lot more where that came from. So, giant molluscs are very much plausible, at least according to many speculative evolution fans. But how? Aspiring speccer vcubestudios wrote this on Deviantart: "Rising out from swamps and marshes, a kind of convergent evolution has taken place, calling back to the days of tiktaalik and protostega. But these were not lobe finned fish, nor were they amphibians. They were octopuses, cuttlefish and squid, mimicking the course of evolution taken by vertebrates eons ago. They waded about in the shallows, slowly creeping onto land. Their shells developed inside of their bodies, even becoming like limbs to support their weight on the earth." Alas, I'm not going to simply cram other people's information into your face and leave. I too am a practitioner of much speculative evolution, so I'll lend some of my own theories to you. The accepted answer tells you that you couldn't get giant molluscs past human-size. That is correct - if the terrestrial molluscs had no skeleton. But that answerer evidently didn't consider the possibility of internal shells. The snails, the nautiloids, and the ammonoids and belemnoids of old are all shelled molluscs. It is by no means unreasonable to think that other mollusc groups could A) evolve shells and B) internalize them. This would serve as an analog of an endoskeleton. I recommend you look at Wikipedia's page on human evolution, to show you how life crawled out of the land and came to rule it. But, a mollusc domination of the planet won't be so similar to ours. What could be really interesting about your future world is that there could be animals with anywhere from one foot (Gastropods) to ten feet (Cephalopods). If you want cephalopods to colonize the land, they'd need to evolve tougher skin and a more adaptable respiratory system as well as that endoskeleton, but they're a very advanced group so I wouldn't put it past them. In the water, molluscs could also evolve giant forms, much more so than on land. One thinks of Spec Dinosauria's Balaenoteuths, squids that evolved into the niche of whales in the absence of mammals: [![enter image description here](https://i.stack.imgur.com/kVPgj.jpg)](https://i.stack.imgur.com/kVPgj.jpg) That's about all I've got for now. I know that you've accepted an answer, but I thought it didn't really consider the possibility of pseudo-endoskeletons, which could dramatically increase the size of your "sandpit" when considering giant molluscan forms. --- I also highly recommend you look at some of these pages (Particularly the one on Balaenoteuths, and that youtube presentation), as they will doubtlessly give you countless ideas. * <https://vcubestudios.deviantart.com/art/Spec-Evo-The-Age-of-Nautilus-Has-Begun-734937569> , to read about speculations on the evolution of terrestrial cephalopods * <https://vcubestudios.deviantart.com/art/Spec-Evo-The-Stalker-734899329> , to explore the possibilities of cuttlefish colour-changing in ambush predators * <https://www.youtube.com/watch?v=BEIlNnkTlIU> - C.M. Kosemen's presentation on cephalods. Seriously, watch this. * <https://dragonthunders.deviantart.com/art/TFiF-Dragonsquids-604647186> , to find out how squids could fly * <https://www.youtube.com/watch?v=jGvE8tr0_lo> , skip to about 43 minutes in for the brilliant Joschua Knuppe's idea of a giant kangaroo-like gastropod * <http://speculativeevolution.wikia.com/wiki/Spec:_Balaenateuthia> , for a myriad of ideas for giant aquatic cephalopods --- I hope this helps, and wish you every fortune in your new worldbuilding project. If you'd like some more informations about speculative evolution and molluscs, a quick Google search of the relevant keywords should yield many more pages. [Answer] It is certainly possible that oceanic mollusk like creatures could grow very large. On Earth there are stories of sperm whales with circular scars much larger than the suckers of any known giant or colossal squid, and having tentacle pieces in their stomachs much larger than known squids. Here is a skeptical post showing how big a squid would have to be to have suckers, tentacles or an entire body as long as some stories claim. <http://cameronmccormick.blogspot.com/2007/03/ludicrous-giant-squid-claims.html> Thus it is possible, though not likely, that some really enormous squid actually live in our oceans. It is certainly possible for smallish octopuses to climb out of water and onto land. <https://news.nationalgeographic.com/2017/10/wales-ceredigion-octopus-land-deaths-spd/>[1](https://news.nationalgeographic.com/2017/10/wales-ceredigion-octopus-land-deaths-spd/) <https://blogs.scientificamerican.com/octopus-chronicles/land-walking-octopus-explained-video/>[2](https://blogs.scientificamerican.com/octopus-chronicles/land-walking-octopus-explained-video/) <http://thekidshouldseethis.com/post/the-abdopus-octopus-walks-across-dry-land-to-hunt-for-crabs>[3](http://thekidshouldseethis.com/post/the-abdopus-octopus-walks-across-dry-land-to-hunt-for-crabs) Clearly it would be just as easy for an octopus like species to evolve into a land dwelling species as it was for fish on Earth to do so. I think that a larger octopus could walk on land easily if it evolved much stronger muscles in its arms. An elephant's trunk doesn't have any bones, but is strong enough to lift a few hundred ppounds. Thus an alien octopus like being with each arm as strong as an elephant's trunk could weigh as much as the combined weight of all its arms added to the combined extra weight they could lift. Octopus-like beings over a few hundred or thousand pounds, and perhaps much lighter, would have to evolve bones in their arms and thus have legs of a kind. And then they could eventually evolve to be as large as the largest prehistoric elephants or even the largest prehistoric sauropods that weighed maybe 50 to 200 tons. But I don't think that giant gastropod like beings could ever move very fast on land, except on the smoothest surfaces which should be very rare. Beings with limbs could probably outrun them on most types of surface - though maybe you can find ways to make them move like the fastest snakes. ]
[Question] [ The origin of [Superman](https://en.wikipedia.org/wiki/Superman) is fairly well known. A baby is sent to a planet and gains super powers from being in the environment (technically the sun, but I believe you catch the gist). I'd like to make a planet/environment that boosts humans in a similar way. What kind of planetary/environmental features would allow for a normal human to be a "super human" and how super human is that? The human in question will only be staying a maximum of 5 Earth days (120 hours) and at absolute minimum 3 Earth days (72 hours). By normal human, I really mean [Navy Seal](https://en.wikipedia.org/wiki/United_States_Navy_SEALs) level of fitness. Please note that the "powers" or increases in abilities are not intended to be permanent. They are mere side effects of being in the environment. Similar to if you begin jumping on a trampoline, you can jump relatively super high in comparison to jumping on normal earth. Requirements/Goals (to properly define what "super human" means) 1. Able to carry or move a larger mass than on earth 2. Has more endurance/stamina 3. See better/farther 4. Able to react to primitive danger faster (primarily for fighting faster and does not require elevated thinking) 5. Any unique or beneficial ability you can conceive of [Answer] ## Greater endurance/stamina: A thicker atmosphere/higher oxygen levels Try a thicker atmosphere - or rather, a planet where the humans largely live at higher elevations. [Altitude training](https://en.wikipedia.org/wiki/Altitude_training) is useful for athletes on Earth. By training somewhere with a lower partial pressure of oxygen, a person's red blood cell count rises, which helps oxygen intake at lower altitudes. This is especially important in aerobic activities such as long-distance running, where respiration is important (contrast this with anaerobic activities, such as sprinting). Your Navy Seal is used to living on Earth, where the oxygen levels are lower than this planet. Therefore, he or she has effectively undergone altitude training back at home. The effects of altitude training can last for a week or two, so five days sounds pretty good to me. [It's been suggested](http://www.humankinetics.com/excerpts/excerpts/the-effects-of-altitude-on-performance) that the best altitudes for training are at 1,200 to 2,500 m. This means [oxygen levels can decrease by up to 25%](https://www.higherpeak.com/altitudechart.html) of their values at sea level. Therefore, maybe an atmosphere of ~25-30% oxygen would be reasonable (see also below). ## Greater strength: Lower surface gravity Try a planet with a lower surface gravity. The stronger the gravity, the harder it is to do normal things, and the stronger the humans will be - and vice versa, for normal humans. In a lower-gravity environment, the natives will likely be weaker; they won't have had to deal with the (relatively) strong gravity on Earth. Thus, this human will be stronger. Here's the thing: Planets with lower surface gravities usually have thinner atmospheres thanks to [atmospheric escape](https://en.wikipedia.org/wiki/Atmospheric_escape) and other processes (oxygen is depleted by these other processes, not atmospheric escape1), so if your humans live at sea level, or its equivalent, [they'd be weaker but would actually experience lower oxygen concentrations](https://worldbuilding.stackexchange.com/a/56858/627). Therefore, we need to mitigate this somehow, possible by having the atmosphere be more like 30% oxygen, rather than 21% oxygen. The relative fraction of oxygen may be higher, but the overall concentration will be lower, and so it will be easier for the Seal to breathe. --- 1 In particular, [dissociation, collisions and non-thermal escape](https://physics.stackexchange.com/a/293790/56299) break up oxygen in Earth's atmosphere. Dissociation happens by the reaction $$\text{O}\_2^++e^-\to\text{O}+\text{O}+\text{energy}$$ This largely happens in polar regions. Collisions with particles from the solar wind then help oxygen atoms and $\text{O}^+$ ions escape. Reduce this rate somehow - perhaps by increasing the planet's magnetic field, to better shield it from the stellar wind - and you could diminish oxygen loss, and thus perhaps increase oxygen levels over geological timescales. [Answer] Everything is relative to the natives of the planet, you don't have to be super-human, you just have to be better than the natives. I think increased strength and stamina has been covered by the other answers. (gravity and atmospheric O2 or pressure changes) As for your other two points I have some ideas. Super Vision: This all comes down to what the natives can do, if because of alternate evolution your natives may have a narrower band of "visible light" making your human have super vision. This is very likely if the native star is radiating in different frequencies than Earth's Sun or if the atmosphere absorbs more light (cloud cover, or different atmosphere constituents). Some materials may appear opaque to the natives but may be translucent in frequencies of human vision allowing x-ray like vision. At the extreme end of the spectrum your natives may be completely blind making sight itself a superpower. Similarly if the natives atmosphere is hazy in certain frequencies, or if their eyes are smaller or otherwise less accurate; their vision may have a limited effective distance, allowing your human to have super sight to see farther than the natives. Super Speed/Reflexes: This one is all about [time perception](https://en.wikipedia.org/wiki/Time_perception). If your aliens have slower metabolic or neural processes, they will literally think and move slower than humans, allowing relatively super fast movement and reflexes. In general colder temperatures will have slower metabolic processes and lower body temperatures in humans have been linked with slower time perception. [Answer] Put more oxygen in the atmosphere Hyperoxic training is used to boost performance and recovery for athletes. Put uppers in the environment There are plenty of drugs that might be naturally occurring in the air water or food that could make a human perform better for a couple days. Generally these have a price when you come down, but 3-5 days could be fine. Amphetamines and cocaine are currently used this way by many people. Reduce the gravity (Like Burroughs' "\_ of Mars" series) Muscles are built for some level of effort, if things are easier you can do more. [Answer] Unfortunately, humans have no hidden superpowers. But in some environments they can perform better than on Earth. 1. Obvious low hanging fruit here is gravity. On a smaller planet, average human can turn into "[John Carter of Mars](https://en.wikipedia.org/wiki/John_Carter_of_Mars)", jumping very high and carrying objects much above his weight. 2. Another factor is oxygen content - an atmosphere with higher oxygen content will provide more energy, allow people to run faster and farther. 3. Atmospheric pressure is a small, but noticeable factor in athletes' performance. So in lower pressure people indeed can move faster. Thinner atmosphere can also improve limits of people's vision. Combining 2 and 3 together may result in an atmosphere that is only 50% as dense as normal, but has over 50% oxygen content. 4. "Doping" in the environment. Atmosphere or water may contain some performance-enhancing substance which people normally have to take deliberately. This is an ambiguous enhancement, but need to mention it anyways. One big caveat is that in reality people would unlikely to become "John Carters". If native species are biologically similar to humans, they will take the same advantages which an environment can offer. So, "John Carter" should have faced martians who could jump as high as he could. [Answer] Avatar scenario. In the movie, the consciousness of the human traverses space to inhabit a new body prepared for it. This new alien body has abilities that his human one did not. If your human similarly has his consciousness placed in a new body, you can have that body be superpowered in whatever way the story requires. Virtual scenario This is like the Matrix, in which human minds inhabit a virtual world. In the virtual world rules are different, and all sorts of powers become possible for the representations of persons within it. Gulliver scenario. In Gulliver's Travels, the hero finds himself in possession of superpowers relative to the natives he encounters - to them he has super strength and size (or later on, the opposite). By native standards, typical human properties (speed, strength, size, intelligence) are superpowered. Accidentally able to use local supertechnology Thinking again of Thomas Covenant - he finds himself in a strange land in possession of magic powers, this because of the metal of the wedding ring he happened to have on. Your Navy Seal might happen to have implanted tech - maybe a prosthetic leg with an AI joint or an artificial heart. On this new world, his onboard tech causes ancient intelligences present there to recognize him (mistakenly?) as one of the Founders, and so entitled to use the powers and technology which remains there, left by the civilization of the Founders. The current natives of the planet may or may not be aware of the Founders and this ancient tech, but if they are aware they cannot access it like your Navy Seal can. This one is nice because you can have your dude with his real body, and native princesses the right size for him to romance, and it is not all fake like The Matrix. Also there are good narrative possibilities in the process of your hero figuring out what exactly he can do and why he can do it. [Answer] So your lift force is given by the equation of kilograms x meters per second² (Mass x Acceleration). Weight is derived from this formula where Acceleration is Gravity (9.81 m/s²) and this is the force working against you in a lifting scenario. So on a planet with 1/5 of gravity, a weight will feel like it is 1/5 less, without altering your mass. Since your body can still lift the same weight the mass would need to be increased to make it the same weight it would be on earth. This was actually the original source of Superman's powers... it just was not sufficient for what he did. There are two things working here. First, if you are 200 lbs on earth than you would be 40 lbs if gravity was 1/5 of earth gravity. This means you are using less energy to move the same amount of mass attached to your body. Another thing you could play around with is that in the animal kingdom, nothing can outpace a human at a distance. In fact, the fastest animal to run an Ultra-Marathon (100 mile race) is the Human. Other traditionally fast animals will tire out long before a human does. This derives from our evolution of pack hunters and use of persistence hunting. Sure... that mammoth might be bigger and stronger and pointer than a human, but it will need to rest before a human does. Humans did not have to best the mammoth at full strength.... they had to chase it until it couldn't run anymore. In effect, we were the Terminators of the Animal world. We were out there. We can't be bargained with. We can't be reasoned with. We did not feel pity, or remorse, or fear! And we absolutely would not stop, ever, until the animal was dinner! We also have a very high pain threshold in for an earth animal and can shrug off some pretty nasty wounds that other animals would go into unrecoverable shock from. In so far as the animal kingdom, we also have some of the best all around senses of any animal (we take for granted things like smell, but that's because we rely on really damn good vision). Humans also have three color vision, which only a few animals (some turtles) have better than, meaning that we can see visible light in a wider spectrum of color than most animals. Additionally, while we don't have the range of say raptors (Birds of Prey, not Jurassic Park) it should be pointed out that they don't have the best close vision sight in the world. I have nothing for four, but five we have two rather unique skills among the animal kingdom. First, while we may not be the fastest runners, climbers or swimmers, we can outclass a good number of animals in a two out of three competition. If the predator runs, it cannot swim. If it swims it cannot out climb, etc. Another unique trait of ours is throwing things. It might not seem like a lot but consider the other apes that are our closest relatives. The gorilla or chimpanzee can throw a baseball at a speed of 20 mph on a good day. An average human can throw with a speed of 60 mph... a pro baseball pitcher can easily do + 90-100 mph on a pitch. And from our physics talk we know that the same mass travelling at a different acceleration means it will feel heavier... the same principle applies. Getting hit by a baseball travelling at 20 miles an hour will hurt, but it's nothing compared to a 60 mile an hour (3x hurt) or a 100 mile an hour (5x hurt). And humans are unique in the animal kingdom in this respect. Again, we might not be pointy enough to go against a jungle cat or mammoth, but we can hurt them first. Most animals never anticipate getting hit by a fastball when they attack. Now, sub out that baseball for a rock, and that's really going to put the animal off to attacking... and keeps us safe by getting our injuries in first before we take our own. And before you dismiss all of that, just remember, a human on human attack (unarmed, just fists and feats, no rocks, guns, knives, what have you) are quite fatal. In fact, they are one of the top five causes of all human homicide. [Answer] ## Reduce the atmospheric pressure Actually, the atmosphere has a weight that is always and constantly pushing out to the ground (not confuse with gravity). Our atmosphere is about 101.325 kPa of pressure, that means 101,325 kN/m2 or 10.332 kgf/m2 of pressure in our bodies. Also, the atmosphere has a density (even low) which increase the friction of our body while we are moving.See at the bottom for water boiling point ## Increase oxygen levels If we increased our atmospheric oxygen level we would be able to perform more exhausting task breathing less and tiring us also less. But, how we can reduce the atmospheric pressure and increase the oxygen level of it? It's very easy: just reduce the pressure while at the same time increase the oxygen percentage. Our atmosphere has 101.325 kPa of pressure (equal to 1 atm and almost 1 bar), reduce the overall atmosphere to only 21-35 kPa of 100% pure oxygen. Remember that a normal oxygen partial pressure is around 21 kPa, and it must be lower than [50 kPa](https://en.wikipedia.org/wiki/Oxygen_toxicity) (oxygen toxicity) but higher than [16 kPa](https://en.wikipedia.org/wiki/Hypoxia_(medical)#Cause) (hypoxia). At higher pressures, fewer you need to breathe. Side note: a bit of CO2 is also necessary, just a bit to prevent [hipocapnia](https://en.wikipedia.org/wiki/Hypocapnia). Also, please see at the bottom for water boiling point ## Reduce the surface gravity It's quite obvious that reducing our gravity (1 G = 9.8 m/s2) will make thing lighter for us. Remember that a lower gravitational force will also decrease the weight of the atmosphere reducing its pressure. However, lower gravitational force can have the risk of [releasing the atmosphere](https://en.wikipedia.org/wiki/Atmospheric_escape). ### Calculate [atmospheric escape](https://en.wikipedia.org/wiki/Atmospheric_escape) Basically, your oxygen molecules must not move faster than your escape velocity. I have already done this kind of calculations in [this answer](https://worldbuilding.stackexchange.com/a/84458/35041) but I'll do them again. So if the RMS [(Root-mean-square speed)](https://en.wikipedia.org/wiki/Root-mean-square_speed) velocity of the oxygen molecule in the atmosphere is equal or greater than the escape velocity of the planet then that gas will escape rapidly and will be absent. $$\text{RMS} = \text{v}\_{\text{rms}}=\sqrt{\frac{3\times\text{R}\times\text{T}}{\text{M}\_{\text{m}}}}$$ * Where: + $\text{Vrms}$ is the root mean square of the speed in meters per second. + $\text{Mm}$ is the molar mass of the gas in kilograms per mole. $\text{O}\_2 = 0.031998 \text{ kg/mol}$ + $\text{R}$ is the [molar gas constant](https://en.wikipedia.org/wiki/Gas_constant). $\text{R} = 8.3144598(48)\text{ J}\times\text{mol}^{-1}\times\text{K}^{-1}$ + $\text{T}$ is the temperature in degrees kelvin (K = °C + 273.15). I'll use 25°C (298.15 K), I think that is the "normal" temperature used in gas calculations where it's specified. $$v\_{rms}=\sqrt{\frac{3\times8.314459848\times273.15}{0.031998}} = 482.096 \text{ m/s}$$ Or simply use [this online calculator](http://calistry.org/calculate/kineticTheoryVelocityCalculator). So we already know that our escape velocity must be greater than 482.096 m/s. ### [Escape velocity](https://en.wikipedia.org/wiki/Escape_velocity) To calculate the [escape velocity](https://en.wikipedia.org/wiki/Escape_velocity) we could use: $$\text{v}\_\text{e} = \sqrt{\frac{2\times\text{G}\times\text{M}}{\text{r}}} = \sqrt{2\times\text{g}\times\text{r}}$$ Where: * $\text{G}$ is the [gravitational constant](https://en.wikipedia.org/wiki/Gravitational_constant). $\text{G} ≈ 6.67 \times 10^{11} \text{ m}^3 \times \text{kg}^{-1} \times \text{s}^{-2} ≈ 0.0000000000667$ * $\text{M}$ is the mass of the planet. * $\text{r}$ is the radius of the planet in meters. * $\text{g}$ is the [surface gravity](https://en.wikipedia.org/wiki/Surface_gravity) of your planets in meters per second squared You can calculate the escape velocity either with your mass and radius or with your gravitational acceleration and radius because they can be exchangeable: $$\text{g} = \frac{\text{G}\times\text{M}}{\text{r}^2}$$ I can't tell you your minimal surface gravity to hold oxygen because it's your decision decide how much will be the relation between mass and radius (density) in your planet (small but denser or big but lighter). ### Water boiling point As [@Tyler S. Loeper](https://worldbuilding.stackexchange.com/users/44804/tyler-s-loeper) suggest in comments, the reduction of the atmospherical pressure will reduce the boiling point of water. So I'll teach you how to calculate that: $$\text{T}\_\text{ebm} = \frac{\text{T}\_\text{ebn} - \text{K}\_\text{SY} \times 273.15 \times (\text{P}\_\text{n} - \text{P}\_\text{m})}{1 + \text{K}\_\text{SY} \times (\text{P}\_\text{n} - \text{P}\_\text{m})}$$ Where: * $\text{T}\_\text{ebm}$ is the ebullition point of a given atmospherical pressure. * $\text{T}\_\text{ebn}$ is the ebullition point of normal atmospherical pressure. * $\text{K}\_\text{SY}$ is the Sidney-Young constant which is $\text{K}\_\text{SY} = 0.0012$ for polar sustances (like water) and $\text{K}\_\text{SY} = 0.00010$ for non-polar sustances * $\text{P}\_\text{n}$ and $\text{P}\_\text{m}$ are the atmospherical pressures. $\text{P}\_\text{n}$ is for the normal atmosphere and $\text{P}\_\text{m}$ for the given atmosphere. Both must be in the same measure (mmHg, bar, pascal, atm, etc). So, using a 100% oxygen atmosphere of 21 kPa and other of 35 kPa (as examples) they would be: $$\text{T}\_\text{ebm} = \frac{100 - 0.0012 \times 273.15 \times (101.325 - 21)}{1 + 0.0012 \times (101.325 - 21)} = 67.19 \text{°C at } 21 \text{kPa}$$ $$\text{T}\_\text{ebm} = \frac{100 - 0.0012 \times 273.15 \times (101.325 - 35)}{1 + 0.0012 \times (101.325 - 35)} = 72.49 \text{°C at } 35 \text{kPa}$$ Any of both number would produce a danger in our body (that is because our body isn't at 67.19 °C!) ]
[Question] [ For example, beans and rice cooperate to make a "complete" protein, providing all of the amino acids the body can't synthesize on its own -- in fact, most traditional dishes that combine legumes and rice are "complete". In this same way, are there three crops that are symbiotic in their nutrition? If a civilization could plant only three crops, which would be best to sustain nutrition and thus life long-term? Cheers! [Answer] Like Bigfoot and the Bermuda Triangle, the "complete protein" thing is a myth that arose in the 70s and lingers in the popular imagination, especially among those with an interest in promoting meat and dairy. You would struggle to get all your amino acids from a diet of iceberg lettuce, but humans can live on beans alone, nuts alone, potatoes alone and so on. <https://fanaticcook.com/2014/08/11/if-all-you-ate-were-potatoes-youd-get-all-your-protein-and-essential-amino-acids/> So you could just grow one crop: potatoes. Which, as a civilization, pretty much puts all your eggs in one basket. You are at risk for famine if your one crop fails, in the manner of the Irish potato famine (yes, many other factors with that event, but they did have 1 crop and it did fail). A deep bench, so to speak, of different crops offers insurance against failure. The other thing is you may have varying types of land available for agriculture, some suited to one crop and some to another. Dry land is good for millet and wet land for rice. Consider millet, grown thousands of years ago in China and Japan as a companion crop to rice. <https://www.npr.org/sections/thesalt/2015/12/23/460559052/millet-how-a-trendy-ancient-grain-turned-nomads-into-farmers> > > For ancient farmers, Jones says, millets would have held obvious > appeal. "Millets are tough in various ways," he says, citing their > short growing season and drought resistance. When the rains fail, a > crop like wheat or rice may fail completely. But millets will > generally produce something, even if it isn't very much. That gives > wheat and rice farmers an incentive to adopt millets. > > > And millet farmers adopt wheat, rice and, more recently, corn > precisely because those crops yield much more. That last point is > probably the key reason why millets have lost their place of > prominence in global agriculture. Wheat, rice and corn have benefitted > vastly more from research and crop improvement, and commercial markets > also became far less interested in "minor" crops. The end result: Many > farmers who once grew a balanced portfolio of crops, including > millets, have switched almost completely to higher-yielding cereals as > cash crops. > > > "It may be time to consider whether millets have a role to play in a > diverse response to crop failure and famine," says Jones. > > > This was more important in the old days and less so now as laid out above - with modern storage and transportation, having side crops as insurance is less important. If you are looking for an unusual crop group for your story (I hope you are) consider the crops of the [Eastern Agricultural Complex](https://en.wikipedia.org/wiki/Eastern_Agricultural_Complex) - the crops North Americans grew before maize showed up and took over. Wikipedia lists goosefoot, sunflower, marshelder, and squash among others. Weeds! [![goosefoot](https://i.stack.imgur.com/3aOjf.jpg)](https://i.stack.imgur.com/3aOjf.jpg). Goosefoot. <http://joshfecteau.com/edible-farm-weeds-white-goosefoot/> If you read about these ancient crops and look at pictures, you will recognize them if you have a garden. Their degenerate descendants are everywhere. But when they were crops they were big and meaty. When the Indians switched to the Mexican crops and especially maize those crops fell to secondary status, and then were lost when those civilizations collapsed. If you want to really do some fiction, imagine yourself in a post apocalyptic scenario and look at the weeds. You could get clues in current vacant lots, or post-Katrina New Orleans. Now domesticate those weeds into crops like out ancestors did. What would they look like? Imagine a leafy field of dandelions, each flower three feet high with seeds the size of rice grains and bitter, nutritious roots. --- ADDENDUM: IS FAT A NECESSARY MACRONUTRIENT? Judging by the comments there is interest in dietary fat and whether it is necessary. Bear in mind while doing your own research: diet arouses passion, belief and behavior like few other subjects. Superficial overviews of diet by organizations like Cleveland Clinic or Mayo or the USDA want to reassure people who are striving to take control of their lives by adopting bizarre diets. These overviews will all say fat is ok because completely eliminating fat from a normal diet will leave a potentially weird and unhealthy diet - like an all potato diet which one would not adopt except out of necessity or mental illness. Fat is ok. It is good energy, and humans need energy which must come from either fat, carbohydrate or ethanol. But except for the 2 essential fatty acids (linoleic and linolenic) fat per se is not essential. It is just energy. Here is [the USDA Essential Guide to Nutrient Requirements](https://www.nal.usda.gov/sites/default/files/fnic_uploads/DRIEssentialGuideNutReq.pdf). I consider it definitive, at least for 2006. There is a lot in there. But there is not a recommended daily allowance for fat (except for milk-fed infants; special case) or a minimum daily requirement for fat. For everything else one might eat, including water, protein, carbohydrate and molybdenum these parameters are given. > > Page 69: The remaining chapters discuss data on carbohydrates (sugars > and starches), fiber, fats and fatty acids, cholesterol, protein and > amino acids, and water. In these chapters, AIs are provided for Total > Fiber, linoleic acid and -linolenic acid, and water, and EARs and > RDAs are provided for carbohydrate, and protein. > > > Page 123 Neither an Estimated Average Requirement (EAR), and thus a > Recommended Dietary Allowance (RDA), nor an Adequate Intake (AI) was > set for total fat for individuals aged 1 year and older because data > were insufficient to determine a defined intake level at which risk of > inadequacy or prevention of chronic disease occurs. However, AIs were > set for infants aged 0 through 12 months based on observed mean fat > intake of infants who were principally fed human milk. > > > The diehard might object that this guide notwithstanding, fat is still essential in the diet, but the data just does not exist to prove it. Data exists for everything else but not fat. I cannot argue with that. [Answer] # 2017-12-17 Added edit with recipes at bottom! # Grain, Root, Legume There are, generally speaking, three major branches of staple crops for nutrition. They each And how is askinghave advantages and disadvantages compared to the others. But most regions of the world are able to grow a mix of these three groups. All three in the mix are important. Will points out that you can live on potatoes alone. This is true, as long as you get 2000 calories a day. However, if you are short on calories with potatoes, then you are also short on protein, iron, and B1/B2/B3 (commonly known as Thiamin, Riboflavin and Niacin). On the other hand, wheat will give you a larger 'starvation margin' on those vitamins. On the other hand potatoes will give you better folate, B6 and vitamin E. All in all, its best to eat both together. Grain crops will generally advantage you in B-series vitamins, iron and protein. They also tend to have the highest yields with the lowest work input, important in a subsistence farming society. Note there are a variety of 'pseudograins' like amaranth and quinoa that I'm going to include with the grains. Root crops are generally more protein deficient, but have a good variety of vitamins and minerals. Root crops also tend to be the hardiest, surviving in case of drought or fire or flood. Legumes generally have the best nutrition and by far the most protein, but they have the lowest overall calorie yield. # Final note: Oils and Leafy Greens There is actually one last group that aught to be included: oils. These plants provide extra fats that are important for things like brain development in children. If you ate only a grain/root/legume you would probably starve to death from lack of fat. However, some legume do double duty as oil crops, like peanut and soybean. Similarly you would probably die from lack of vitamin A/C/E/K. Some plants provide one of these (potatoes for C, sweet potates for A) but overall you need some vegetables in the diet to get these minerals. On the other hand, you can eat the tender green shoots of just about anything growing for some of these vegetables, so they probably aren't important enough to consider. # Possible combinations by regions of primary cultivation ### Tropical Africa (old world origin only) * Grain: Sorghum, Pearl Millet, Finger Millet * Root: Yams (genus Dioscorea) * Legume: Bambara groundnuts, black-eyed peas/cowpea * Oils: Palm oil ### Tropical Americas (new world origin only) * Grain: Maize * Root: Cassava, Sweet Potato (Genus Ipomea), Arrowroot * Legume: Common Beans, Runner beans, Peanut * Oils: Peanut ### Mountain Americas (new world origin only) * Grain: Amaranth, Quinoa * Root: Potatoes, Yacon * Legumes: Common Beans * Oils: Sunflower (really more of North America than Mexico) ### Fertile Crescent * Grain: Wheat, Barley, Rye * Root: * Legume: Chickpeas, Lentils, Peas, Broad Bean * Oils: Olive, Flax ### Europe * Grain: Wheat, Barley, Oats, Rye * Root: Turnip/Rutabaga * Legume: Peas, Broad beans * Oils: Flax (Note: lack of oil crops is a big reasons Euros were so into dairy!) ### NorthEast Asia * Grain: Wheat, Foxtail Millet, Buckwheat * Roots: Yams (genus Dioscorea) * Legume: Soybean, Adzuki bean * Oils: Sesame, Soybean ### South Asia * Grain: Rice, Pearl Millet, Sorghum * Roots: * Legumes: Pigeon Peas, Chick peas, Mung Beans * Oils: Sesame, Mustardseed, Cottonseed Note: China, especially south China is kind of halfway between NorthEast Asia and South Asia, and grows lots of things from both categories. Also, as you can see, not all regions had each category I only included things that are commonly grown now. # Pick just three After checking out some nutritional profiles, I have two top choices: * Tropics: Peanut, Corn, Sweet Potato * Temperate: Oats, Potato, Soybean --- # Recipes I was so intrigued by the concept that I decided to test it out. What would you eat with the three growable crops? I started with the tropical crops so here goes ### Ingredients * 8 White Corn Tortillas * 1 cup peanuts * 2 Medium sweet potatoes * Peanut oil for frying * Salt [![enter image description here](https://i.stack.imgur.com/aJeAE.jpg)](https://i.stack.imgur.com/aJeAE.jpg) * Take 1 cup of peanuts and grind with a mortar and pestle and 1 cup of water, to make a runny peanut paste. Basically, watered down peanut butter. Salt the peanut butter, and add any spices you were going to add. Also, if you aren't a peasant, just use a blender if you don't have all day. + Bake two sweet potatoes wrapped in foil (or a big leaf from the woods, if you're a peasant) for 1 hour. Poke some holes in the skin before you put them in the oven * Fill frying pan with 1/4 inch of peanut oil. When you're starting out, 1/2 inch might be easier. * Fry tortillas on each side for about 30 seconds; they should not get crispy. Fold them over on a plate to give them that taco shell shape. See figure above. * Cut up potato, divide into portions, and put into shells. * Spoon peanut sauce on top, and serve. See figure below. [![enter image description here](https://i.stack.imgur.com/6v116.jpg)](https://i.stack.imgur.com/6v116.jpg) I didn't want it to be too bland, so I added a couple birds eyes chilis to give it some heat, and help with some vitamin C. You could add other spices like pepper or allspice, if you wanted. The meal wasn't too bad. It was a big heavy, and if I did it again I'd try to throw some iceberg lettuce or cabbage or something in the tacos to add a bit of crunch to it. Bon Appetit! [Answer] Generally, all crops have some content of minerals, vitamins, protein, sugars, and other stuff, because they need it themselves. In your case, I would go for the most reliable and non-demanding (if you know the correct term let me know) crops. I think for a civilization, you need 4 kinds of crops--medicinal, foodstuffs, fibre and something for bio-fuel--so I will try to reflect this. ## Onions and garlic They are a natural source of antibiotics and are some of the most common herbal spices in the western world. They have a lot of vitamins too. ## Pumpkins and melons While this seems strange at first, pumpkins are easy to grow. They also can be used to feed animals and contain enough sugars to make alcohol, which can be used as a biofuel. And the hidden value of these crops is that they can be used to grow penicillin, very useful. ## Beans or cabbage or potatoes Beans are easy to grow and have a lot of protein; they are easy to preserve and store, and they also taste great. :D Cabbage is the middle ground: not as demanding as potatoes, but still a good source of daily food. It can be also used to feed animals and is easy to preserve. Unlike other crops, you can eat it raw without any problems. Potatoes are most versatile, but also the hardest thing to grow and preserve. They can be used to feed animals, contain a good amount of vitamins, and contain starch. You can make alcohol from potatoes. BUT it's a pain to grow them. They require intensive care, a lot of water and fertile soil to produce a good yield. It is a lot of work to plant them and then get them out of the ground. They are susceptible to blight and have many pests. They also need to change fields often, or they will rot in the ground. ## Flax or cotton Flax is more demanding than cotton, in terms of time and work, and it's harder to extract fibres out of it to make linen. But it is hardier than cotton and can grow in colder climates. Its seeds can be used for oil and for preserving wood (I don't know if other oils can do that too). Linen cloth is also said to have some antibacterial properties (but I don't know if that is a myth). Cotton has its limitations, but is easier to harvest and process. Its seeds can also be used for oil. But it requires a lot of water. ## Mulberry While not exactly a crop in a traditional sense, it can be used for its fruits, which can be then eaten as food or processed into alcohol. It can also be used to cultivate silkworms to produce silk. Silk has the strongest fibres, good for medical and warfare applications. So mulberry checks 3 out of 4 boxes. ## Oats Oats are the most durable and most non-demanding of grains. They are also one of the healthiest. And they can be used to feed strong animals, like horses. > > My personal pick would be cabbages and flax and garlic (or onions; it does not make much difference). Linen from flax can be used for > padded armour and durable clothes. Flax also allows me access to oil, and > fermented oil is useful for curing wood. Garlic will make the > population healthier overall; it gives me 2 spices in one crop, > making my food less bland, and it prevents common intestinal parasites. > Cabbage can feed the masses and can be preserved in large amounts, while > requiring very little preparation. > > > These are not all, but these will do. Edit: Other plants from other people: > > addition by - Draco18s > > > Kudzu > > > Kudzu is good for baskets and clothes(...apparently), It has some > medicinal use(\TL;DR), It can not be used for oil, but according to > wikipedia it can be used to make cellulosic ethanol (just like any > other plant). It provides only starch, starch is not tasty, if it has > some kind of taste at all, so the other crops would need to complement > that. Kudzu hay is also a pain to store, because it can get wet > easily, but it is great for big animals. But It is a noxious weed and > it can go rogue easily, which could cause some problems, It also > depletes soil quickly, if it is harvested. > 2.5 / 4 good find. > > > I think, that Kudzu, goes well with mulberry and hemp. (Asian trio) > > > addition by - Jules > > > Hemp* > > > Hemp provides rough fibres, that are good for ropes and bags, but they > are not the best for clothes and they do not like humidity. Some types > of hemp have medicinal use ;) And their seeds can processed into oil. > 3 / 4 good find. > > > [Answer] The canonical combination for a three-plant-garden would be what was called a [three sisters garden](http://faq.gardenweb.com/discussions/2766718/three-sisters-garden) - corn, beans, squash. This combination was used by [Native American tribes](http://www.nativetech.org/cornhusk/cornhusk.html) as a set of [major crops](https://en.wikipedia.org/wiki/Three_Sisters_(agriculture)). The plants [grow very well together](https://www.gardeningknowhow.com/special/children/a-three-sisters-garden.htm), with symbiotic contributions, they also store pretty well (well, with winter squash and dry corn, not so much summer squash or milk corn), and they're a pretty decent staple diet. Of course, this wasn't all they ate... the addition of meat and fish from hunting, wild and foraged foods, and other kinds of cultivated plants were used for variety, seasonings, nutritional supplements and alternatives, medicinal use, and a score of other things. And I'm sure it helped that even within this combination, there was a lot of variety to be had - different cultivars of corn, different kinds of beans or squash. But the combination of these three crops were the bulk of the agriculture for many Native American tribes, and mainstays of their diets. In any case, I think the history of this set of crops is decent enough to make them a good candidate for your civilization, especially if more than one variety was allowed, or at least varieties with a lot of internal variation to maximize the chances of selective breeding letting them diverge into multiple complementary strains. I think it would help a lot, though, and might be within the parameters of your question, to allow your civilization to supplement these foods with hunting and forage (and/or garden medicinal plants) even if these are the only food crops. [Answer] If your intention is that this is all they eat in a simple fashion, it almost certainly can't be done. Even with modern technology, it is extremely difficult to eat a healthy vegan diet, and especially so for young children (there have been several horrific cases resulting in malnutrition). Dietary supplements are necessary to ensure health; and that's eating a varied vegan diet with all the produce the Earth has to offer not just three. Even if you could find three unlikely plants which contain a complete set of micronutrients, they will be present in the wrong proportions. You need advanced processes to extract and prepare the right nutrients. But feeding animals, and brewing, can fill the gap. If you instead take a proportion of the produce and feed it to animals you can then eat the animals to get a much richer, more complete, diet very easily. Brewing allows the diet to be supplemented with booze (which is nice) and, more importantly, allows yeast extracts to be made from the by-product. Under these circumstances you want a grain suitable for brewing, a tuber good for animals, and something else - probably a bean of some sort - but you're much more flexible in what you crops will suffice. In another answer it is suggested that eating solely potatoes would suffice. This is, unsurprisingly, complete rubbish. Quite apart from the near total lack of multiple vital dietary nutrients (including vitamins A, B12 and E, and minerals calcium, sodium and selenium) which would result in malnutrition, they're also high in glycoalkaloids which doesn't matter in normal consumption but faced with the roughly 3kg/day every person would be required to chow down in order to meet their daily calorific requirements the levels consumed would be much higher and likely result in poisoning symptoms. As usual these problems would be more acute in the young than the old; it is much easier to maintain an existing healthy human than grow a new one. [Answer] I suggest grass as the main one. This way you can raise cattle. You can eat their meat and drink their milk. ]
[Question] [ ## A planet with changing gravity On earth gravity stays constant (besides negligible fluctuations), but it may be possible to change that. What kind of geology, natural satellite, or other anomaly could cause periodic changes in gravity? (And what magnitude of difference would they have). The ideal goal is to map the change to a kind of sine wave, so that the bounds of the changes stay constant. The periodicity of the planet's gravity can range from days to years. [Answer] The gravity on Earth is changing. We see it in the tides of our oceans. The tides are caused by the Moon and the Sun which exert a gravitational pull on all the mass of our planet, but exert a greater pull on the parts of our planet closest to them because gravitational attraction decays with distance. The Moon isn’t very massive and the Sun is a long way away so on Earth the tidal forces aren’t very large, but if our planet were to orbit something very large and very close these tidal effects could become significant. If a moon orbits a large enough planet too closely, the gravitational gradient can overcome the gravitational self-attraction of the satellite and cause it to disintegrate. This distance is called the [Roche limit](http://en.wikipedia.org/wiki/Roche_limit). A body near the Roche limit will have reduced gravity on the sides facing directly towards and directly away from the body it orbits, but will have normal gravity elsewhere. Any bodies in orbit will exert tidal forces on one another. These forces can range from nearly imperceptible, as on Earth, to making anything on one side of the planet that isn’t held down float off into space. The magnitude of these forces will depend on the size and density of both bodies and the distance between them. As long as the planets are not tidally-locked (rotating so only one side of the planet faces the other as our moon does) the gravity will change periodically, as the tides change on Earth. Additionally, an eccentric orbit could also introduce changes to these effects with the desired periodicity. [Answer] A very massive planet with an extremely high rotation speed would have an huge gravity gradient between the poles and the equator. The classic sci-fi book "[Mission of Gravity](http://rads.stackoverflow.com/amzn/click/B00QFMNTTG)" by Hal Clement exports [such a world](http://en.wikipedia.org/wiki/Mesklin). [Answer] If your planet had a stable micro black hole orbiting inside it (well below the mantel) gravity would vary by location depending on the orbit of the black hole. Of course, such a planet would eventually be doomed, as the black hole would absorb more and more mass until it had absorbed enough to do catastrophic damage to the planet. Just how a black hole would form a relatively stable orbit within a planet is left as an exercise for the reader, but unexpected results from a super-collider might be a good start. [Answer] My best guess would be some how an ultra dense piece in the mantle is circulating in the planet. Say a (very large) clump of lead (or even something more dense) that from some reason is moving around in the mantle of the planet. As it orbits the core, it changes the 'center' of gravity and affects gravity on the surface. I would expect if this is even possible, that it would in reality be a very slow rotation, maybe once in a humans lifetime or once in a thousand years for a circuit to complete, but maybe a very active planet might have it more often, and that might be why it's a lot more active, say something large collided with the planet and everything hasn't completely settled down several million years later. [Answer] For the exact formulation you'd need a lot of maths and simulation, but if you only look for a feasible explanation, what Mike says is the easiest way to explain a changing gravity. Big orbiting planets can stay at equilibria even when their orbits go one across the other, even when planets are almost nex to each other for a period of time. Therefore, you could explain the changes on gravity that way: When another orbiting planet goes nearby, gravity is way stronger towards that planet. Also, a big "star" (it's a planet, not a star, but people might be unable to differentiate) appears on the sky for that duration of changed gravity, which is really interesting from a mythological aspect. If you want even more variation, add more planets to the "equation". That way, the mythology around that goes even deeper. Every planet, with it's distinguishable bright and color (since star's light are reflected differently) brings a different gravity and for a different duration of time. [Answer] How about the following. 1. The planet has three layers, one is the rocky mantle, one is the metal core. 2. The third layer is intermediate between the two others, and somehow has low friction. I am thinking along the lines of a liquid here, so we will probably need to postulate high temperatures for an appropriate material to remain liquid. 3. The mantle rotates at one speed, e.g. 1 rotation per 24 hours. 4. The core rotates at a different speed, e.g. 1 rotation per 30 hours. 5. The core is unevenly distributed density. We could postulate the core has absorbed a particularly large incident body some time back, that for some reason has never quite migrated to its geometrical center. I am not saying this situation would be stable forever, but why not over a geologically insignificant and biologically large period, like 10 million years? [Answer] Along similar lines to the black hole scenario, you might have some weakly interacting dark matter orbiting inside the planet. You need the dark matter to clump together and to have minimal interaction with normal matter. A candidate for this would be [Weakly Interacting Massive Particles](http://en.wikipedia.org/wiki/Weakly_interacting_massive_particles#WIMPs_as_dark_matter). Wikipedia references a paper suggesting they would tend to clump together - I am not sure how well validated this is, but good enough for a story. Note we still have to worry about the Roche limit, whether inside or outside the planet. I think that if it is dense enough, it will be stable. [Answer] A easy and fun way to do it is to place several moons orbiting your planet. They have different trajectories in space, for example almost comet like for one, thus coming only once a decade. The other moons could be orbiting in whatever way you want. * Chaotic tides, magnetic filed perturbation if one moon is highly metal. * Extreme events might occur when all celestial bodies align creating strange gravity impact (high jumps or whatever). I would keep it simple but if you are ready to push yourself, nothing better than the usual duo planet orbiting one star with a moon or 2 to gear things up. There you got retard gravity. [Answer] A few of the answers here propose a very high-density mass located off-center in the planet's core, along with the different rotational period of the core to the surface, leaving the problem of how this mass came to be there in the first place. What about the opposite scenario? A moderately-sized cavity in the planet's solid core, off-center - which could either be filled with a significantly lower-density material, (helium perhaps?), or simply be a vacuous void in the core. As with the other explanations, with the core's rotational period differing from that of the surface thanks to the liquid outer core between them, the position of the planet's center of mass would shift relative to the surface geography. But a region of lower density material is, perhaps, easier to explain than one of highly dense material - a mining operation, a chemical reaction (the other reactant being less abundant then the core material, it eventually ran out), or even being scooped out by a rogue wormhole. [Answer] # an industrial accident In a universe with something like [Tensor–vector–scalar gravity](https://www.wikipedia.org/wiki/TeVeS), a Type II civilisation (in its early days) created wormholes or warp drive. [Sean Carroll](http://www.preposterousuniverse.com/blog/2012/04/20/puzzles/) has a few youtube videos that cover Dark Matter: one in particular is more in-depth for TeVeS, but I can find it right now. He uses the less-technical version in several talks. I find it interesting that TeVeS implies a preferred reference frame for gravity— exactly my favorite way to make FTL travel safe for the arrow of time. He explains how the Ve and Te fields would allow interesting gravitational phenomena to exist (if we can find a way to express it). So, it all fits: a wormhole hub ruins or an "accident" leaves behind something that makes the additional fields mess with gravity. That civilisation is long gone, and new intelligences are dealing with it. Or maybe it's current and some people have to put up with that as, say, an inherent part of doing business at a major shipping hub. [Answer] Expanding on the satellite solution and the issue with the Roche limit. The Roche limit goes as the cube root of the relative densities. If $M$ refers to the planet and $m$ to the satellite: $d\_{Roche} = R\_M(2\rho\_M/\rho\_m)^{1/3}$ It follows that if the satellite is twice the density of the primary, the Roche limit is not a problem. So, make your primary have low density and the satellite nickel-iron. For added amusement: * The satellite can have a highly elliptical orbit. * Have more than one satellite. [Answer] It is really a planet? I'm thinking of David Weber's Mutineer's Moon. (There are other stories in the series but this is the relevant one.) It turns out Earth's moon was actually destroyed 50,000 years ago--what we see in the sky is a starship on long term picket duty that was concealed by peeling off the outer layers of our moon and covering the ship with them. There was a mutiny, the ship was severely damaged and remains there to this day inhabited only by the now-sentient computer core. The gravitational anomalies we see on the moon are really the result of the mass distribution of the underlying starship. While it does nothing that changes the gravity of the moon it certainly would be capable of doing so. [Answer] If you want to play around with what's going on inside your planet, feel free. Gravity is defined as $F=\frac{Gm\_1m\_2}{r^2}$, where $m\_1$ and $m\_2$ are the masses of the objects in question, $G$ is a constant, and $r$ is the distance between the two objects. Since $G$, $r$, and $m\_1$ are all constant, you can have the inside of the planet change its mass by some chemical reaction (unobtanium?). As $m\_2$ increases, $F$ increases; as $m\_2$ decreases, $F$ decreases. [Answer] Well, with gravity you mean probably gravitational pull at the surface. So there are some possibilities: * the planet gains and loses mass somehow; * the planet expands and contracts (thus changing the pull on the surface, the differences have to be big to be noticeable); * some extraplanar very heavy and near astronomical body causes tides; * big rotational changes (while not really influencing gravitational pull the centrifugal force would work in the opposite direction and would so lessen the weight of things on the surface). And naturally: the world simply has different laws of physics. It is hard to think about a scenario how the planet loses and gains mass. Something I think of: the planet has an enormous part of its mass in the form of water, that is stored underneath the crust. Some events lead to evaporation of it, so the main mass of the water is leaving to higher atmosphere and raining later back to the planet. Still complicated. The other possibilities are also difficult. Expansion and contraction of the crust in big style is something I have no idea about how it could happen without breaking suspension of disbelief. Same thing about changes in rotation speed. Some big mass (say a pretty heavy moon) might sound believable, but it seems something that big induces strong tidal forces that will lead to reduction of rotation speed around each other fast (as happens with the moon of the earth, it shows already the same side to the earth at all times, because of the tides induced from earth on the moon and the tides the moon induces on earth will other time lead to the moon being at the same place over the surface of earth at all times). So I would go with a world of different physics. The force of gravitation is changing regularly. ]
[Question] [ For some time I've been working on a universe with non-instantaneous Faster-Than-Light travel, but I've decided to open a new universe with instantaneous travel. So I'm working on the differences that the two modes of transport necessarily enforce on the societies that use them. The first question that occurs to me is this: If ever planet in the galaxy is effectively equidistant from Earth is there any point in colonising anything that's less than almost perfect? In the four years it was working [Kepler](https://www.theguardian.com/science/2017/jun/20/we-are-not-alone-nasa-telescope-finds-10-earth-like-planets) found that of the 200,000 stars it surveyed, that's roughly one one-millionth of all the stars in the galaxy, 50 had an Earthlike world in their Goldilocks zone. With instantaneous interstellar travel that puts 50 million Earths within easy reach, would we colonise star systems without easily habitable worlds or would those systems be left empty until we had packed the good worlds with people. Jack Campbell's [Lost Fleet](https://en.wikipedia.org/wiki/The_Lost_Fleet) does a good treatment of what might happen to worlds colonised when slow FTL was the only option after the introduction of a faster travel option but I'm wondering about the impact on colonisation choices in a setting where there is no slow option. Good answers should focus on reasons why there might be a push to colonise systems without Earthlike worlds at the same rate as systems with them. Assume that travel to/from every star system in the Galaxy to any other has the same cost in time, energy, materiel. [Answer] # You get [The Commonwealth](https://en.wikipedia.org/wiki/Commonwealth_Saga). I highly recommend the Void trilogy The Commonwealth in the saga of the same name is an Earth civilization that worked out Wormhole transit. Which is effectively instantaneous FTL. There were limitations to how far they could connect two ends of a wormhole, but even with a near infinite distance, you still have a different problem: Finding inhabitable worlds. Sure there are a lot of stars out there and they have a lot of planets, but you still need to spend time and resources surveying them and determining them safe for human colonization. This will slow your empire's growth. They'll likely start with the nearest systems and work outward. In the Commonwealth there was effectively only one corporation that ran the wormhole networks and they only used a single wormhole to explore for new planets to colonize. If they used more, it wasn't too many more: most of the wormhole network was devoted towards providing transportation from planet to planet. As long as new worlds were being opened for colonization regularly, to keep up with increasing population numbers, there really wasn't a need for more. Even so they didn't pass up "90% good" worlds, as provided that a population could move in and start building infrastructure immediately it was sufficient. That is: * Atmosphere isn't toxic * Any native life isn't overtly hostile * One planet depicted in the series was one that looked great, but later turned out to have carnivorous grass. They lost two explorers inside ten minutes before terminating the connection. * Any planet that can be terraformed for cheap ("eh, its got water, but no plant life. Steve, order up 400 billion tons of sod, would ya?") It was generally seen that even if it took some effort to survive, that was fine, there were still folks who'd be up for moving in. Heck, some planets that were less "idylic" turned into manufacturing worlds where the toxic pollutants from less-than-clean industries couldn't really screw the place up. It was better than poisoning the atmosphere of an inhabited world! [Answer] Actually, this is a good question. I need to make an assumption: * Given that the cost (economic, energy, time, etc.) of colonizing any planet in the galaxy is for all intent and purposes equal, what would be the motivations for colonizing any particular planet? So long as I'm not too far off-base with my assumption, the reasons people colonize vary according to the pressures motivating colonization. 1. Resource developers are looking for the best bang-for-the-buck. The cost of getting there may be equal, but the cost of setting up operations and (for example) mining the planet for all its gallium is not. A planet rich in gallium with a toxic/acidic atmosphere may represent a lower value-to-cost ratio than a planet less rich in gallium but with a Mars-like atmosphere. Further, you can't just develop them all because too much gallium on the market lowers the price and makes the overall value-to-cost value really drop. 2. Pharmaceutical developers are looking for the best bang-for-the-buck. They want planets with either very unique biomes or very diverse biomes. This does not necessarily translate into biomes suitable for general colonization. A diverse biome could develop in an atmosphere too harmful for humans (containing a toxin, or even a biological agent consequential to the biome itself). 3. Colonists are looking for the very same bang-for-the-buck. But they want the planet that represents the highest chance for very-long-term survival with the lowest cost to survive. Sure, goldilocks planets are high on that list, but a less diverse biome is also suitable if the planet has all the other checkboxes in spades. Planets with a lot of wood/trees are more valuable than planets with very mountainous terrains. Planets with a high percentage of fresh water access compared to salt water are more desirable than planets with large seas, etc... And this depends on how many people want to colonize at any given time and what the rules for colonization are. If everybody is clamoring to get off Earth due to pollution, some will be willing to take less valuable planets simply because they want off, now. So, I can easily imagine the following occurring as a consequence of all these pressures that may drive people to consider different kinds of "perfect." Hunting planets becomes big business The cost of transport to any planet in the galaxy may be the same, but we're still talking about hundreds of billions of stars. ([Google claims 250 billion +/- 150 billion](https://www.google.com/search?source=hp&ei=bG9LW-mpLsXbjwTx55boAg&q=how+many+stars+in+our+galaxy%3F&oq=how+many+stars+in+our+galaxy%3F&gs_l=psy-ab.3...619.4198.0.4375.0.0.0.0.0.0.0.0..0.0....0...1.1.64.psy-ab..0.0.0....0.g_ekLKVoH5Y).) A single person needing a single second to hop from planet-to-planet, spending just a single second at each planet (assuming an average of 325 billion stars and just one planet per star), would need 20K years to visit them all. So planet hunting is a booming business. The race is on to find them, catalog them, and present them to the market because the commission for locating those best-of-the-best planets are enormous. Planet hunting would create an entire industry all by itself. A planetary exchange Today water, mineral, agricultural, and building rights are occasionally sold separately for the same parcel of ground. The value of the planet to the individual buyer who wants all of them is higher than to individuals that just want a part of the whole. Planets that are rich in all of them are the most desirable of them all. The exchange would easily look just like today's commodity exchanges where people are bidding to take possession of each planet's key value or the whole. Exchanges would be frequented by megacorporations, colonization clubs, governments (as more valuable investments than bonds), etc... Why is this important? Because there's always a cost By removing the cost of transportation you've simply shifted the cost to something else. I predict that something else is the cost of acquiring and developing the world. Why would somebody settle for less than perfect? Because they can't afford it. [Answer] The reason why people would colonize planets which don't have much atmosphere or gravity is because material can be lifted into orbit more easily. This makes it easier to use the planet's raw materials to build infrastructure in space. It's completely possible that people would want to build [Dyson Swarms](https://en.wikipedia.org/wiki/Dyson_sphere#Dyson_swarm) instead of just landing on an Earth-like planet. The biggest advantage to using a Dyson Swarm is your ability to incorporate the entire mass of the planet into living space, instead of just using a thin shell on the surface (even if we build a full kilometer up and down everywhere, [not even 0.1% of the Earth's volume will be used](http://www.wolframalpha.com/input/?i=2km%20%20earth%20surface%20area%20%2F%20earth%20volume)). This allows for taking a planet that could hold a few billion people and turning it into space structures which can hold trillions. On Earth, it is difficult to raise matter up into space because you need to use big, expensive rockets. With smaller planets that don't have any atmosphere, you can launch matter up into space with a [railgun](https://en.wikipedia.org/wiki/Railgun) for a lot cheaper. Our Moon is perfect for that purpose as it has a lot of mass, but no appreciable atmosphere (it technically has one, but it's atmosphere is as thick as an industrial-grade vacuum chamber), so there is nothing to stop us from launching metal off the surface to build orbital infrastructure. Another advantage to this method is that you can make your environment as Earth-like as you want. With an [O'Neill Cylinder](https://en.wikipedia.org/wiki/O%27Neill_cylinder), you can replicate, the air, gravity, temperature, etc. as well as you want, or you can pick other values as you wish. With settling Earth-like planets, you might have to suffer with 27 hour days, freezing temperatures everywhere, 1.3 G's of gravity, or other slightly annoying differences. With space habitats, you can pick the temperature, the spin-gravity strength, the day length, etc. however you want. So, in the end, the push actually could be for colonizing, not systems with Earth-like worlds, but systems with worlds like our Moon. And for those who argue that we can do this with asteroids: the entire asteroid belt has about [4% of the mass of the Moon](https://en.wikipedia.org/wiki/Asteroid_belt). You'll have a lot less matter to work with if all you can use is the asteroid belt. [Answer] Colonization means permanent inhabitation. There is only one reason why your people would colonize less than ideal systems: they are pushed there by others of their kind. Lots of people commute in to work in the city even with a non-instantaneous commute. The easier you make it the more people would do it. If the commute to NYC were instantaneous and easy, why would anyone with a choice live in the city? People would live at a distance where it is green, cheap, cool and clean, zap into the city to work, then zap back out when the day is done. So too your people. They can live in places that are nice, then commute in for shifts. Maybe they would stay for days or weeks, like the crew on a fishing boat. No fishermen live on the boat all the time. They might sleep there when they are working but they live on land somewhere that is way nicer than the boat. As regards your systems with no earth like worlds: a person will choose to live in a less than ideal environment because it is the best choice, or because they have no choice. There is more to a living situation than the weather. Maybe like the Mormons were, your colonists are persecuted for their differences. Maybe population pressure and lack of places to live in the nice worlds have driven them out. Or the authorities have forced them out and into a suboptimal environment of the authorities choosing, like the US government did when it moved the Cherokee from green Georgia to Oklahoma. It does not matter how fast the trip back and forth is because these people can't go go back. Refugees of this sort will colonize suboptimal territories out of compulsion or necessity and then go to work improving their circumstances as best they can. [Answer] Companies would explore to find suitable planets because they would own the right to any discovered planets and sell tracts of land as well as charge migration fees to settlers. Big groups of settlers might buy the rights to a planet so they control who can come and go and effectively own their own planet. Religions like Scientology would love to own their own planet would pay billions for the right. I would imagine that companies would map out suitable planets using robotic probes. The first probes will just jump into a system, take a snapshot and basic measurements and then jump to the next system and repeat. The probes will return home to transmit the data when they need to refuel. A probe might only have to spend a few seconds in a system to get the basic data needed. Once a possible planet is found, a second scientific probe is sent to scan the planet. It would map out weather, geological features, possible colony sites, mining sites as well as testing for possible life that might exist. Planets with life already on it wouldn't be allowed to be settled on. Either human borne viruses and bacteria would wipe out that life or aliens viruses and bacteria wipes out Earth born life. The risk would be too great and only scientific robotic probes would be allowed to land (mostly never to return). That said, life bearing planets would be worth big money to the company that found them. With suitable dead planets, they would have to terraform them. This would involve dropping specifically engineered lifeforms on the planet to create a human sustainable atmosphere. Once terraformed, what you would find is people would colonize those planets as quickly as humanly possible. You wouldn't find people waiting until a planet is full before moving. Firstly there are people who don't like being close to other people. They will move just to have nobody else around. They're quite happy building their own homes, generating their own power and growing their own food. There is a good chance these people make up the terraforming crew. Next you have the people wanting to build wealth. Land on an empty planet isn't worth anything until people start turning up. The more people turn up, the more the land is worth. If you arrive early and claim large tracts of the best land, your children, grandchildren and great grandchildren will end up very wealthy. Finally you have the dispossessed. These are the people who have no reason to stay. An overcrowded planet may not have the work and owing a home is impossible. Perhaps discrimination is forcing you to move? War? Famine? These people will move because they have to. They move now on Earth even though they might not have anywhere to go. If they can go somewhere where they can live in peace they will leave. Basically as soon as a suitable planet is found, people will move there. [Answer] The temptation will great to colonize the best Earthlike planets first especially distance, time, energy and materials costs will be the same. Certainly there were those who do so with a vengeance. The most Earthlike planet in the entire galaxy is seventy thousand light years away. Not a problem. It is just as easy to get there as that less Earthlike habitable planet tidally locked around red dwarf star only fifteen light years distant. The answer seems obvious, but is it the best choice? The answer is probably not. The more Earthlike a planet is the more there will subtle problems like allergies, all that alien protein in the form of pollen floating around, and organisms that are likely to have sufficiently similar biochemistries that humans are either edible fodder or excellent host for infection. In fact, the more Earthlike planets can be the more problems like this will multiply. OK, so it's got a breathable atmosphere, seas you can swim in, but if you're constantly wheezing, sneezing and coughing with hay fever and other allergies or afraid to go in the water of hungry marine behemoths where's the fun in that? If you have to always wear an environment suit for protection you might as well have colonized a planet with a poisonous atmosphere and have done with it. There is an even better reason to colonize non-Earthlike or less Earthlike planets and especially this in orbit around red dwarf stars. Stars similar to our Sun will move off the main sequence in roughly one billion years or less while red dwarf stars remain on it for around a trillion years. Any canny colonizer with an eye for the long-term will know sooner or later, what's only a billion years between friends, will have to move from their all tto Earthlike planets when their primary star goes red giant and eventually white dwarf. Also, while the numbers of Earthlike planets is relatively small there are huge numbers of planets waiting to be settled in orbit around red dwarfs. By the time the First Galactic Empire is well and truly established the vast majority of inhabited planets will around red dwarfs, therefore, this means this is where the greatest mass of the galaxy's population will be. They will have the voting power. Meanwhile the descendants of those impetuous colonists who rushed to take over what they thought were the best and nicest, but definitely Earthlike planets will be left in smaller numbers of galactic citizenry, with less voting power, wheezing and sneezing in their handkerchiefs. It will be those with a view to the long-term who will see the advantages of colonizing and settling the less Earthlike planets. Programs and organizations administering the colonization of the galaxy will run parallel schemes for settling both the Earthlike and the less to non-Earthlike planets. The two schemes will be of equal size and scope because they will be planning for the long-range future. [Answer] Lots of good points have been made already, however here's some more point that hopefully will also inspire someone. There's more to it than Earth-likeness.* Why forego a perfectly liveable planet for some lifeless rock? When there are other parameters in the equation. The first and foremost answer is because you aren't the only one in the universe. Other civilisations beat you to the punch and already picked some choice planets for themselves. You aren't in a warmongering mood, and besides there are other planets to be had. But it means that maybe you'll have to settle for a second rate neighbourhood. Rules and regulations are also an universal buzzkill. Imagine any plant life or animal life is protected, and killing those might be bad for your public image. Damned space-liberals! In these conditions, and since there is a planet that fits your needs and also doesn't make you look like an evil corporation, you'll sooner start mining asteroids or pump fuel from gas giants than risk angering the space-EPA or the space-UN. Or maybe you look for a cool planet, maybe one with ice volcanoes or rings or with a pink sun. It isn't particularly practical or beneficial, nor is it particularly impractical or detrimental. It might make for a good photo-op at the very least. Last thing to consider is some people might purposefully look for the least practical planet to settle, either for the challenge or because they believe in hardship, or in cases like the military to make sure the troops are capable to sustain anything. In the end, organisations will push towards different directions to suit their needs and limitations. They'll still look for the most favourable conditions available, but that doesn't mean picking only Earth-like planets. "Almost perfect" is highly subjective after all. Scarcity, and lack thereof. Now for the consequences. I should preface, this is only one possible scenario. There will be a drive toward space travel, and the cost of it will lower. You will eventually reach a point where going from planet to planet is cheaper than taking a taxi to the airport. In fact, more people will travel through space than by taxi. Practically, you'll have immediate access to infinite resources at a cost so ridiculous low it might be as well be free. The free market economy doesn't like infinite supplies because that means prices tend towards zero. You will need to reinvent the economy plain and simple. Then I can envision two extremes: the corporations fall, or the governments fall. Scenario one is the old economy falls. Companies go ounder, jobs disappear, so does wealth. But from the ashes rises a new society, a society where the state provides for everybody, where you get everything you need, and where everything is awesome. Think Star Trek, that would be the most hopeful example of a post-scarcity universe I can think of. Scenario two is people start a revolution, heads roll and governments crumble. Corporations are free to act without regulation and the law becomes their to dictate. Parliaments are replaced with admin boards, ministers with executives. Corporations become micro-states, they'll own planets, healthcare, armies, and ultimately people. Welcome to cyberpunk hell. [Answer] When new planets are opened up, they are effectively colonized, and the rules of the interplanetary civilization imposed on them. These may not be agreed on by everybody, for example the beautiful planet of Maui-Covenant in the Hyperion series is immediately turned into a vacation spot, which ruins its ecology within fifty years. To a Capitalist society, this is good and right, because lots of money was made. The only way to avoid this is to live somewhere that isn't interesting to colonize, not even with the possible slave labor of its inhabitants. The place needs to be sufficiently hostile that no one wants to vacation there, it needs to be poor enough in natural resources that it doesn't make sense to strip-mine it, and the population needs to be [largely illiterate](https://yalebooks.yale.edu/book/9780300169171/art-not-being-governed) so any colonizers would not find local clerks for their administration and would have to bring lots of expensive off-worlders expecting a high standard of living in the colonies as well as hazard pay. So, the perfect planets are basically air-conditioned shopping malls, and living space for the richest, with resources pulled in from other planets in order to conserve the rich forests serving as hunting grounds. Less than perfect planets house clerks, workers and light industry, and mining and heavy industry are relegated to places with lots of resources and low gravity. And there'd be the "uncivilized" places, where all the interesting stuff happens. [Answer] Already lots of great, in-depth answers here, just wanted to add another explanation for colonizing non-ideal planets: some colonists might settle sub-par worlds for political and ideological freedom. To avoid disturbance by a certain establishment, they might pick planets that no one else would care for, that no one else would try to eject them from. This is similar to the exodus of Puritans, who set out to colonize Plymouth Rock for cultural independence, because who else would want to move to a garbage state like Massachusetts? [Answer] Since you didn't exactly specify the parameters of your instantaneous travel, for my answer I assume the following: You can travel to a location instantaneously, if and ONLY if you were there before, setting up infrastructure for instantaneous transport. That would be something akin to a pair of star gates, you need gates at each end to be able to travel. This would mean you first need to FIND your perfect planets. You figure out a planet is in a Goldilocks zone. You use non-instantaneous FTL travel to reach this planet, you see it works, but unless you actually visit EVERY OTHER potential planet, you never know if you are perfect, just if it's good enough, or better than previous colonies. Obviously you could in a way automate setting up infrastructure, but this would take a very long amount of time. An example of this in fiction would be the the seed ships in Stargate Universe, taking million years to install stargate infrastructure. Would YOU want to wait millions of years for the ideal colony? [Answer] ## Why do they want colonies in the first place? It's likely true that for colonies with the purpose "Earth is too crowded, lets go somewhere else!" they would pick planets very much like Earth, or even better if they find one (I suspect the planet entirely made of beautiful sandy beaches and perfect weather would be popular). However, there are very many reasons to visit a place other than "I want to live there forever!". Some examples: ### Natural resources Earth-like planets are, naturally and intentionally, very much like Earth and fairly likely to have similar limitations. On the other hand, there could be quite a lucrative business opportunity if you lay claim to [the planet made entirely of diamonds](https://www.space.com/18011-super-earth-planet-diamond-world.html). Or, since diamonds aren't incredibly intrinsically valuable so much as kept in intentionally restrictive supply, substitute some other rare material that people want more of. The actual difficulties involved in your instantaneous travel might affect what is economical here, but I would be surprised if there's NO planet that can supply some material more cheaply than terrestrial sources. When one is found, claiming it could require a permanent garrison to dissuade others from doing the same. ### Vacation spots While there might be some particularly good locations for permanent residence, there are probably other locations that are really cool for a few days but not really inherently comfortable. The previously mentioned planet of diamonds probably has some interesting views that make for a good postcard, but with such little diversity of local materials I suspect absolutely everything you can get there would be ludicrously expensive (with the exception of tacky souvenir diamonds) so it's mostly popular as a luxury vacation spot. Maybe some moderately wealthy family could afford an annual trip to a different exotic planet each time, but naturally they prefer the "exotic" be safely on the outside of comfortable climate controlled domes and exciting guided tours; in other words, a thriving industry of "colonies" on various planets based on "interesting" rather than "can sustain a lasting population". ### Science While current space travel hasn't reached the point where resource mining is more than a pipe dream, and space tourism hasn't passed the "I swear we'll find a way to do it!" stage, we've been sending scientific missions to many extraterrestrial bodies for decades; with every planet we can find available, I can't imagine we would stop. We have semi-permanent science missions in Antarctica despite it being a truly inhospitable location, because SCIENCE; I suspect Mars would be the same if we had better GTFO plans and less time needed to get there. ### TL;DR Planets like or almost-like Earth would probably be popular for true colonization (motivated by crowding or independence or whatever), but other planets much less like earth could still have interesting and desirable traits that would encourage a permanent settlement regardless. [Answer] > > If ever planet in the galaxy is effectively equidistant from Earth is there any point in colonising anything that's less than almost perfect? > > > Because there is value in colonising something now instead of waiting. You bet that if there are now some known planets which are "good enough", they will be colonised -- even if in the future it's bound to find something "almost perfect". Space is a big place. The almost perfect place may be quickly reachable -- that only has value if you know where it is. And even after "almost perfect" places have been found, there will always be people picking the lesser places. The "almost perfect" place will be prime real estate: expensive, and crowded. There will always be demand for cheaper and quieter places. [Answer] You need to present a whole lot more information. How does the transporter work (operationally)? Do you dial in a range and distance? Do you specify "coordinates", and if so, how are they determined? Is this a "magic" transporter which will automatically find a level spot on a planetary surface and deposit you there (with zero relative velocity)? (Note that I find that one preposterous, but you're the author.) For interstellar transportation, it's clear that you're talking about a single-station transporter, a la Star Trek. More conservative send/receive booths won't do, since you have to get to the destination the first time the hard way, and that just won't work for galactic-scale travel. What, exactly, is the cost of a jump? Not only in energy (and its associated economic factors), but things like computation time? How do you handle relative motion? If you jump into space near a body you will be accelerated in some direction. If you reverse jump, what happens to the speed you've built up? This could make recovery operations just a bit tricky. Different parts of the galaxy (even neighbor stars) have wildly different velocities - how does a traveller handle the difference when she appears in a different star system? If it's not "magic", a planet-finder needs to be in a spaceship. In general, we don't know the distance to any star, let alone its planets, with any great precision, so presumably it will take quite a few jumps to fine tune a location. Furthermore, the ship needs to be of good size, since (among other things) it needs to be able to actually find a planet once it's in the star system. And that's not necessarily a quick process, since it effectively requires mapping the star field over a period of time and looking for apparent motion. If you don't jump into the system well above the plane of the ecliptic, you'll also need to be prepared to map twice, the second time after you've jumped to the other side of the star. The spaceship does not, in principle, need a lot of maneuvering capability, since it can always jump near the star, build up velocity, then jump to a point chosen so that the transferred velocity vector is a stable orbit. BIG NOTE - If you can do this cheaply you've got the makings of a perpetual motion machine or over-unity generator, and this has other issues. But also note that, unless operation is essentially (operationally) instantaneous, the ship is vulnerable while a new jump is being computed. If such computation takes appreciable time, you can't have "panic button" which permits recovery from a jump into a Bad Place, like too close to a target star. So you've found a good planet and you're in orbit around it. Now what? How do you get down? On earth, LEO has an orbital velocity of about 8 km/sec. If you attempt to jump down to the surface, what happens to that velocity? If you have to get down the hard way, you'll need reentry vehicles. The more capable the RVs, the more expensive the main ship, and the fewer the number of companies in the business. So now you're on the ground, the atmosphere is breathable and the temperature is OK. What now? How long before you're comfortable that the local fauna and flora won't find you crunchy and good with ketchup? Diseases? Allergies? It would be pretty mind-boggling to find that the local biochemistry is both compatible and friendly. But let's finesse that one. What, exactly, does the end-user (as opposed to the explorer) get out of a new planet? If it's just expansion of a country, the exploration effort will be carried out by a governmental agency, not a private one. And unless the jump cost is really, phenomenally dirt cheap, shipping new infrastructure to a new settlement is going to cost out the wazoo. The settlers can do it, in time, but it's chancy. Take fuel, for instance. Do you have any idea of the effort required to find oil deposits? Or the sheer amount of materials that go into a refinery? Unless you postulate a bootstrap process, the amount of stuff that needs to be shipped is mind-boggling, and a bootstrap process is going to take decades. Lots of prospectors (many of whom will die) over a large area. Minerals found, maybe - but maybe not, stuff is where you find it. Small-scale extraction. Small-scale transport. Build-up of scale. Meanwhile, everybody has to be fed and clothed, and without the infrastructure (and working in a new biosphere which is sure to have unpleasant surprises, especially if it's compatible) agricultural productivity will be low, so you'll need lots of farmers who don't live all that well. Plus, of course, once they do get up and running they may well take the position that they'd rather keep what they have rather than sending it "home". Remember, it's been decades and their kids think that the local planet is home. Send in robotic factories to exploit rich mineral finds? Sure, but if you've got robotic factories, why not use them at home? It goes on and on. Unless the transporters are really, really cheap, it's hard to see why anybody other than the desperate poor or the ideologically insecure would take plunge. And with this sort of customer base, it's hard to see how it would become big business. ]

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