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[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. Given that a laser beam is made up of coherent light waves running in parallel in the same direction, and that space is not a complete vacuum (dust, radiation, electromagnetic forces etc.), what kind of effective range could a laser weapon have in space? And what form would a laser take, once technology has progressed to the point where a laser is reliably weaponisable? Power requirements and wavelength? Additionally, what form of defense could a spacecraft use against lasers? A mirrored hull? A thick ice shield? I'm assuming an initial contact distance of several hundred kilometers (call it 150 miles if you like), closing as the two combatants approach each other. Is this a realistic expectation? The environment in question is in the asteroid belt and the ship is powered by a nuclear power source. [Answer] The equation for the power emitted by a laser beam at a distance in a circle of radius $r$ at a distance $z$ where the beam diameter is $w(z)$ is $$P(r,z)=\frac{1}{2}\pi I\_0w\_0^2\left(1-e^{-2r^2/w^2(z)}\right)$$ where $I\_0$ is the initial intensity and $w\_0$ is the initial beam diameter (see [these course notes](http://www.pa.msu.edu/courses/2010fall/phy431/PostNotes/PHY431-Notes-GaussianBeamOptics.pdf)). If we assume that the entire diameter of the beam hits the target, then we can set $r=w(z)$ and get $$P=\frac{1}{2}\pi I\_0w\_0^2\left(1-e^{-2}\right)$$ We could write $I\_0$ as a function of the electric field amplitude $E$ and the characteristic impedance $\eta$ (see [this presentation](http://www.rpgroup.caltech.edu/courses/aph162/2007/Protocols/Optics/e3872_Gaussian-Beam-Optics.pdf)), but it might be better to just work off of numbers. At any rate, this equation assumes that all of the beam hits the target, which isn't necessarily the case. Were we to use [the world's most powerful laser](https://web.archive.org/web/20080614224504/http://newton.ex.ac.uk/aip/physnews.401.html#3), we could get around 1.3$\times$1015 watts of power - for half of a trillionth of a second. Let's think about beam divergence, and the [Rayleigh length](https://en.wikipedia.org/wiki/Rayleigh_length). This is the value of $z$ for which $w(z)=2w\_0$. It is given by $$z\_R=\frac{\pi w\_0^2}{\lambda}$$ The NIF laser operates at a wavelength of 351 nm ([Haynam et al. (2007)](https://lasers.llnl.gov/publications/pdfs/haynam_applied_optics.pdf)), with all 192 beams being focused through a hole less than 1 mm in diameter. Assuming that our lasers have beam widths of about this much, then we have a $z\_R$ of ~22 meters. That's not good. However, this is because the beams must be so small. The [Boeing YAL-1](https://en.wikipedia.org/wiki/Boeing_YAL-1) could have been effective at up to 300 kilometers (see [a summary of a report](http://www.aps.org/about/pressreleases/boosts2.cfm)). So if we up the power, then we could in theory get results more like the ones seen at NIF - really, really explosive. A couple hundred kilometers should be achievable. Laser shielding is a whole different problem. At these energies, there's not a whole lot that can stop these lasers. Most things will catch fire or blow up (or both). Heck, that's why the NIF uses them! One option is to use a shield of "trash" - basically, laser cannon fodder. It gradually gets eaten away by laser attacks. Problems: 1. It blocks the vessel from doing anything (seeing the opponent, launching missiles, etc.). 2. It's temporary, must be replaced, and may not last long. A second solution might be to use a [shielding gas](https://en.wikipedia.org/wiki/Shielding_gas). This is commonly used in industrial welding to absorb some heat from welding lasers. I have absolutely no idea if it could work. You would likely need to rig up a magnetic field to contain it (if possible), and it would obscure visible light. But it might be better than nothing. [Answer] Hde's answer can only really be expanded on at the Atomic rockets site (<http://www.projectrho.com/public_html/rocket/spacegunconvent.php>) which has links to many other sites, calculation tables and worked examples, so I will talk about defense. The short answer is that most ideas of defense against laser weapons are rubbish. A mirrored hull could reflect 99% of the incoming beam, but the energy impulse will be so short and sharp that the remaining 1% will damage the mirror and allow subsequent shots to burn through the hull. Ablative materials will be rapidly burned away and even rotating the spacecraft will just cause a crazy quilt of burn lines to cover the ship before something fails (and a rotating spacecraft will already be under a great deal of stress). If you have something which can stop a particular laser, the enemy will be working on a more powerful laser weapon (bigger mirror, shorter wavelengths, the same output packed into shorter beam emissions etc.) with the ultimate weapon being the RBoD (Ravening Beam of Death); a Free Electron Laser with an accelerator a kilometre in diameter capable of delivering a beam of x-rays out to one light second (almost the distance from the Earth to the Moon). A full description is at the end of the laser section at Atomic Rockets (above). So if he can vaporize you from a light second away, and cause considerable damage out to a light minute, how do you respond? Defensively, you would have to carry a massive amount of material to absorb the incoming energy. A huge ice shield will absorb much of the incoming energy, and the heat will be dissipated in the mass of ice. The advantage of this is the high energy of the beam will likely vapourize and ionize the water, creating a plasma which will tend to absorb even more energy and travel "up the beam", blocking the laser's punch (although if the RBoD is a light second away, this don't do you much good in the long run). The downside of this is it becomes extremely energy intensive to move your ship at all, much less make combat manoeuvres, so the RBod can gradually cut your ship to pieces. A ship can be built relatively cheaply and easily from water ice (see <http://neofuel.com/iceship/index.html>), so you might try to overwhelm the RBoD with sheer weight of numbers. This leads to the other approach, which is active defense, or fighting fire with fire. Rick Robinson's Rocketpunk Manifesto site (<http://www.rocketpunk-manifesto.com>) often talked about "eyeball frying contests", where lasers attempt to fire down the optical paths of enemy lasers and destroy the optical train. This makes a large number of assumptions which can be questioned, but is a reasonable idea in principle. Counters to that include using external bomb pumped lasers as warheads on drones and missiles, or randomly directing the optical train to different fighting mirrors between shots. The other approach is to attempt to overwhelm the RBoD with thousands of incoming kinetic energy warheads. These have been given the nickname "Soda Cans of Death" (SCoD), indicating they are about the size of a soft drink can delivered in massive quantities. Since even small objects moving at orbital and interplanetary velocity have massive amounts of kinetic energy, the impact of even one could cause considerable damage, so the fire control system should be programming the RBoD to try to clear the sky of incoming SCoDs, rather than shooting at you. At some point, there are more targets than the RBoD can deal with (cycle times, overheating, repositioning the mirror etc.), so it goes down under a hail of KE strikes. (Too bad they were also shooting busses full of SCoDs back at you at the same time....). Space war will be very messy, and involve filling the sky with thousands of sensors, weapons and mutually supporting systems (you don't really think there is only one RBoD out there, do you?). I suspect the great expense of all of this will make any real space war more theoretical, much like WWI dreadnoughts spent much of the war in heavily protected bases, glowering at each other across the North Sea because the risk of losing a battle was so great compared to the potential gains of winning. ]
[Question] [ Imagine a war in a standard fantasy world, roughly medieval, most magic is limited, but magical healing exists. Healing comes in three forms: 1. Rare Healers, who are born with ability to do rapid magical healing, taking even severely injured to full health in minutes. However, they exhaust their own Healing energies rapidly doing so, and thus can only heal a few wounded this way before exhausting themselves entirely. These are far rarer than trained medics, but not unheard of, and a number will be available to each side in a battle. If a Healer exhausts his energy, it can take a few days to fully recover. It is easier for a Healer to heal recent wounds then old ones, though having time to focus on Healing without rushing, and ability to triage who to Heal better, means that they can heal a slightly more effectively if not in the heat of battle even if the wounds are a little older. After a battle, once healers recover their expended energies, they will work to heal those wounded from previous battles, but since the wounds are now much older, they can not heal these older wounded nearly as fast. 2. Alchemical potions that can be used for healing. These potions are usually not as rapid, but can heal someone back to fighting strength in between a a number of hours to a few days depending on injuries and potions used. Alchemy is more than "`x` potion heals `y` damage". It takes trained Medics to know how to use these potions well, combining them correctly for different injuries; and more potions doesn't necessarily mean faster healing. These resources are more far more common then Healers, but still limited in supply and carefully triaged. 3. General first aid and 'mundane' healing, supported slightly by some simpler magic, mostly to lower odds of infection, but still requiring slow healing process and risking potential death. Limits of the other resources mean many have to settle for mundane healing still. I want to know how this affects battle conventions in general, but for this question I'm focusing on how enemy wounded and medics are treated. In our world you DO NOT attack those who are too wounded to fight, and doctors/hospitals are very strictly off limits. Of course, in our world wounded are rarely going to end up fighting against you in the near future. It takes too long to heal. In fact leaving wounded cost your enemy far more in resources to tend to the wounded then if you killed the wounded. In this world though leaving wounded may mean fighting them again next week. Most will still relay on mundane healing, all the rapid healing options are still limited in resources, but a non-trivial number can be rapidly brought back to the fight. Lets say after a week roughly 10% of wounded will be back up to mostly-fighting strength, with a mostly negligible number healed every day after since the easily treated are already healed. This assumes good supply lines, long campaigns would mean more careful triage of Alchemical potions and later battles may see less healing due to lack of supplies. In this world will wounded or those that treat them be off limits? Or will they now be too large of a tactical threat to leave off limits? What are the chances that making killing blows on wounded is a standard tactic? Will flanking to get to your enemies medics and kill them be a valid and honorable tactic? Perhaps the rules will vary for healing: magical Healers are fair game, Alchemists are a grey area, and mundane treatment still of limits? Related, what are the odds of something like the Geneva convention affecting this (there will be a neutral party that helps to negotiate these sort of conventions and has a limited ability to encourage sticking to a convention by lowering aid to sides that don't stick to them, but is not powerful enough to enforce anything if both sides don't want a convention)? Is it likely that sides will agree to either leave certain wounded/medics off limit or agree to emphasis saving most lives possible at expense of being able to heal fewer to the point where they may rejoin the fight; something that would be tactical suicide unless you're certain the other side will do the same? [Answer] We have a lot of fancy rules to try and "civilize" things, but ultimately war is about *destroying your enemy. Whether you will resort to killing the wounded and/or medics, however, depends on the situation. "Civilized" Conflict* Imagine a scenario where two neighboring countries routinely scrap with one another over minor territorial issues. They may be fighting today, but they know they'll be trading with one another again in a few months. They won't want to permanently damage the relationship between them by performing "barbaric" deeds. They'll keep things "civilized" - kind of like a duel of old, when two gentlemen would face off, and maybe even kill one another, but with no "hard feelings". They may go so far as to heal the enemy's injured soldiers, and to offer extensive medical assistance to the defeated party after the fighting is over. Healers would likely be off limits as targets, and if you happen to capture your enemy's hospital you will treat their healers are guests more so than hostages, or prisoners. A Serious Fight In a more escalated situation, such as when one country is trying to completely conquer another (think American Civil War), it will make sense to take out the enemy's ability to remain in the fight. Executing the healers or wounded might be a little extreme, however depriving them of healing supplies, or killing as many of the soldiers as possible while "no one is looking" would probably be an acceptable tactic. On the surface neither party would engage in anything scandalous, however behind the scenes some pretty nasty things may occur, because each party wants to win, and the stakes are very high. (for example the Americans took to sniping the British officers at any opportunity, which the British considered barbaric, but was very effective at disrupting the flow of battle). All-Out Slaughter Last but not least, fighting may be taking place between two sides which positively hate one another, and who truly wish to see each other become extinct (Turks and Kurds, anyone?). In this situation *nothing* is off the table. The focus becomes eradicating the enemy by any means - and that includes the civilians, not just the wounded and healers. So yes, in this case it would make *perfect* sense - to the point of it becoming a priority - that one would target the enemy's healers, and execute their wounded. It would be very demoralizing to the enemy, as well as making their soldiers fear getting wounded - no more quick healing, etc. [Answer] This covers many things that you, as the world-builder, must simply decide! There can be arguments for and against answers to your questions. Maybe this can be a simple cultural difference between two armies; one kills medical staff and the wounded, while the other does not. # Falling In Combat [Lindybeige talks about falling in battle](https://www.youtube.com/watch?v=SFX9Vk9ttZs). He makes some good points. They are: * Fallen individuals can fight. * Fallen soldiers actually reach further on the ground, cutting at ankles but lose mobility. * Recovering hurt individuals is usually a priority for comrades-in-arms. This is just human behavior; if a friend is in trouble, you help them. You would expect commanders to place more importance on recovering the wounded if they can be fighting in the next battle, or the battle after that. People who have been trained, have a special skill, or are otherwise important to a functioning army will take priority. Killing fallen fighters and prisoners can be tricky, but has been done. Famously, at the Battle of Agincourt, [King Henry](https://en.wikipedia.org/wiki/Battle_of_Agincourt#Henry_orders_the_killing_of_the_prisoners) ordered the death of many prisoners. Supposedly this order was not only for troops' safety, as the prisoners outnumbered the captors, but because they would slow them down too much. # Attacking Healers Obviously, the more effective healers in your world are slower. Since they're a limited resource, you would expect them to be reserved for the more critical components of an army or organization. Denying an army that resource has obvious advantages. However, killing unarmored individuals is a scruple most people have. This, simply, comes down to culture. Do you hate your enemy so much that you want them dead, or [are you trying to achieve something](https://www.youtube.com/watch?v=ju_D_1Xp3wY)? Does attacking healers serve a general's or one side's purpose? Are there social or religious taboos against doing so? # The Original Geneva Conventions [Chivalry](https://en.wikipedia.org/wiki/Chivalry) set the standards of behavior for knights in combat in Europe. Japan had [Bushido](https://en.wikipedia.org/wiki/Bushido). Arabians had [Furusiyya](https://en.wikipedia.org/wiki/Furusiyya), which had ethical considerations. Cultures appear to make rules about what is and is not acceptable in combat. It's something that you must ultimately determine for your world, and the cultures therein! [Answer] Here's a way to think about it: it sounds like a healer can heal one person per day for their entire life. A healer with 50 years to live can heal 18000 people in their lifetime. So getting that healer killed is as bad as getting 18000 of your civilians killed. So: I don't think there are healers on the battle lines at all. Consider: most nations will have conventions about not killing healers, but: * when you're firing arrows at the enemy, sometimes you're going to hit healers purely by accident * there's always the chance that the enemy nation will get desperate and violate the convention * even if you don't want to kill healers, you're probably just fine with capturing them and using them to heal your own people. It's possible that a large army might have one or two healers in it, heavily protected, for healing "important" people. But most of the healers (and most of the nations) have done the math: a healer can save just as many lives in a big-city hospital as they can on the front lines of the army, and keeping the healers well-protected in the hospital is way way safer. (Reference: in a comment [here](https://worldbuilding.stackexchange.com/questions/31429/psychological-effect-of-rapid-magical-healing-on-soldiers-during-a-battle) you wrote: "there isn't enough magical healing to go around. Many have to wait for natural healing because they aren't deemed to need the limited magical healing as much as some other cases" -- which is how I know that healers have plenty to do in big-city hospitals.) --- As the number of healers in the population increases, eventually we reach a point where (barring some sort of major catastrophe) every hospital has enough healers to heal everyone that reaches a hospital. At that point it starts to make sense for healers to be in places that aren't hospitals. This is when healers start getting deployed into the military. [Answer] For enemy wounded, if they are taking prisoners, most would probably get traditional medicine once the battle is over and your own wounded are cared for. There are a few reasons why this is a good practice: 1. If your doctors will help their wounded, they are less likely to be attacked by the enemy. 2. A enemy prisoner makes for a good hostage to help guarantee that your own captured soldiers are treated humanely. 3. If an enemy knows they will be treated humanely, they are more likely to surrender instead of fighting to the death. A man with nothing to lose will fight a lot harder than someone that knows he'll get fed and a place to sleep if he just stops fighting. Just figure, if you're picking off their healers, they probably will do the same. A lot of countries agree to rules before battles, as it just makes things more civilized. If you break the rules, you know they'll give you no quarter. For your own wounded, on the front lines you'd probably deal with alchemical healing the most, used to stabilize and fix up wounded so they can be taken to a medical center. At the medic they would assess the situation of each injured, see who would be ok with just the battlefield alchemy, and who needs extra attention. When demand for the healers is high, they probably wouldn't try to bring everyone back up to 100%. Maybe just to the point where they are in no danger of dying from their wounds, and then turned over to alchemy or traditional healing methods. This is so that the healers can help the maximum number of people before being completely drained, and so if a special case comes in that needs to be completely healed there will be something available. [Answer] Healers would have to be protected from overwork due to the high demand for their ability. Assuming that like anything else a person could push themself over and above normal limits to the point of self injury. It is possible that healers could be convinced or coerced into over extending themselves even unto permanent injury or death. How many would survive to have children? Healers would likely be a highly prized resource, protected even fought over. Failure to protect them could result in them dying out in just a few generations. Alchemists would probably be treated much as pharmisists are in our world unless they also require the healing ability to create their potions. ]
[Question] [ A question blatantly inspired by my old question here: [What would be the impact of a modern programmer and laptop being dropped into World War II, possibly breaking Enigma?](https://worldbuilding.stackexchange.com/questions/12129/what-would-be-the-impact-of-modern-programmer-and-laptop-being-dropped-into-worl?rq=1) I had so much fun with the idea that I went back and reread it today and noticed that I focused a lot of my question on Enigma, but others suggested uses based entirely off of its raw number crunching ability alone. Thus let's try an altered version of the same scenario that focuses only on that second part. Again, our time traveler somehow falls through time, unexpectedly, while headed to his last final for college. Unlike the previous question he didn't have his computer with him. However, he does have his graphing calculator and a cheap smartphone, along with a newly purchased 12 pack of batteries and his smart phone charger ([I'm waiting to see how safe it will be to charge the smartphone though](https://worldbuilding.stackexchange.com/questions/30826/modern-technology-during-ww2-can-it-be-powered-safely)) He's fallen in time to right about the time when WW2 was starting in Europe, but he is in his home in the United States. He somehow manages to get in contact with someone high enough in the government or military to be able to put him into contact with those who would be interested in him and convince this person of what his calculator can do. He is relatively intelligent and was about to receive his bachelor's degree in software engineering, and has a decent 'dabbler level' understanding of physics, science, history of computers/software development, etc. However, his hardware knowledge is limited to what he had to learn for his degree, not enough to tell them how to build a computer. In addition while he is familiar with many aspects of his graphing calculator he has never done any real programing for either the calculator or phone, and has no way to look up the API for either now; heavily limiting his ability to program anything complex, but allowing him to manage at least basic scripts on his graphing calculator. To keep the focus on computation power, and keep him from being too game breaking, assume that the time traveler has very little interest in most history, and particular was not interested in war history. He has a below average knowledge of WW2, and while he may have vague knowledge of a few key battles existing: D-Day, Pearl Harbor, Midway, etc. he remembers little specifics and in particular has no idea about the time-frame for these events. Between his limited historical knowledge, his uncertainty of what he does know, and the timeline changing as he interacts with it he has little to offer in way of direct intelligence about the war or what to avoid. His long term goals are the increase of quality of life and general benefit of humanity (regardless of their home country) and to accelerate the development and adoption of technology. His short term goal, more relevant to this question, is the ending of WW2 as quickly as possible with minimal lost of life, which he considers best done by aiding the Allies war effort to speed up the Axis defeat and thus minimize the lives lost during a drawn out war. What can the the traveler do with his two powerful computational devices to affect WW2? Where are his resources best allocated to maximize their benefit? Any suggestions for how he can also drive his longer term goals, enhancing tech and quality of life, at the same time he is working towards ending the war are welcome! I'm interested in any answer for helping the war effort, but if some option meet those long term goals at the same time all the better. [Answer] If he can get himself assigned to the Manhattan Project, to help with the building of the bomb. With his calculator he might be able to speed up the project by months or even years. We might even be able to make enough fast enough to use one on Berlin. However, with the way government works, most likely they would confiscate the calculator, jail the man for even knowing about the Manhattan Project and just give the calculator to a research team they think has the most important need. [Answer] In the end the Allies broke all the Axis codes. Maybe the graphing calculator could do it quicker if the time traveler partnered up with a cryptologist. It wouldn’t end the war significantly sooner. The tool itself is not understandable enough to give a leap in technology until much later. I estimate the 1970s. His best bet is to make a program that can make him money either by predicting stocks, or perhaps selling computational time to big scientific endeavors. Then he could use this money in combination with his knowledge of future events to know what to invest and promote to propel advancement forward faster and share it with the developing world. In the end it comes down more to his knowledge then to the machine itself. The machine is limited to manual input and only displayed output. This is not a Star Trek tricorder after all. [Answer] Using the calculator to break the codes would only be a temporary solution, once the AXIS forces knew the codes were broken they would change them. This is what, according to some historians actually happened, look up the bombing of Coventry, the enigma code had been broken (and not with any help from Jon Bon Jovi) but by ordering the evacuation of the city or setting up more air defence around the city than would normally be present would make it obvious that the Allies knew about attack and had cracked the enigma coded messages. However it's the mundane things that the time traveller could potential effect that could make the largest changes. Imagine just going back 70 years and telling them that not only what was possible but had been done, man on the moon, nuclear power, flat screen tv's. Even a basic understanding of some of the technologies that exist in the future could allow the WWII scientist to know where to look, what to research. How much faster would it be for the scientist trying to researching the best material to make a transistor out of and our time traveller says "not sure how they work but they're made out of silicon". Possible months of time saved by not have to test all the other possible materials. This is of course assuming the time traveller doesn't end up in a state hospital with an ice pick up his nose... @The transistor example is just that, an example. It was used in an attempt to show that even a little bit of future knowledge of how a particular technology works when given to an expert could alter the timeline on the development of that particular technology. @Churchill vs Coventry Air raids- I did say according to some historians and again it's an example. IF it happened or didn't doesn't change the basic point that blatantly displaying the fact you've broken you enemy's ultra secret encryption will only make them change the encryption. Unless the information gained from the broken code can be attributed to other sources, recon, resistance movements within occupied territory etc. You would only be able to use information directly from a broken code once or twice before the fact that it had been broken would be know to the enemy. @Sarriesfan It's an parable, an example, a story told to get across a specific point. I think your focusing to much on the story I told and not the point I was trying to make, for which I apologize. Can we know draw a line under it? ]
[Question] [ I am assembling a small group of nomads that will soon begin developing into a civilization. However, there are a couple small details that I have to work out first. The first little intricacy that I have to iron out is what my people use when they have to wipe their behinds. I want their method of backside cleaning to be as accurate/similar to what early nomads (think nomads before settling in Mesopotamia) would have done. Would they use a leaf, just let it sit there, bathe it out with water, or use some form of toilet paper if any of these? If they did use some kind of toilet paper, then what would it be made of? Thanks a lot for any insights into ancient derrière cleaning! [Answer] You would use [what you had available](http://mentalfloss.com/article/48950/what-did-people-use-toilet-paper). For any number of biological reasons it would not be ignored by the populace at large. The common use of paper was surprisingly a more recent development than people might assume (paper was rather valuable elsewhere for quite a while). In its absence, all manner of clever thinking seems to have been employed from corn cobs in the revolutionary war to sponges on a stick in ancient Greece. Biological functions don't much care about the convenience of the occasion and as one famous lawyer discovered: "when you gotta go, you gotta go." Ultimately, as far back as you go, nothing quite beats the utility of the human hand and a "bucket" of water (assuming you even care about sanitation!). [Answer] Wipe with your left, eat with your right. <http://indiatour.dadaksa.com/etiquette.htm> > > In India, as all across Asia, the left hand is for wiping your bottom, > cleaning your feet and other unsavory functions (you also put on and > take off your shoes with the left hand), while the right hand is for > eating, shaking hands and so on. (makes sense for Hygiene!) > > > [Answer] I agree strongly with the thought that they used what was available. But I'm also pretty sure people just used their hands. In fact, I think there are cultures that don't wave because it's insulting to show someone the hand you wipe with, but I can't find it in a brief search. ]
[Question] [ Rogue parties in fiction have a tendency to appear as...filler, which to a certain extent makes sense as they usually form a launching point for the story meaning they aren't terribly important long term. In building my world I am creating a setting for a specific story, but I am also creating a world that may act as a sandbox for other things down the road. See: [How can I make a shared world less restrictive?](https://worldbuilding.stackexchange.com/questions/23861/how-can-i-make-a-shared-world-less-restrictive/23865#23865) My world has a tribal region with perhaps a dozen sizable tribes, they are from a similar cultural background but often fight between themselves so they are certainly different in ways. That leads to this question: How can I create non-state groups that are not simply stereotypical, living in the woods, (or other remote biome) technologically backwards, spiritualists or bumpkins? I am looking for a system here as I have roughly a dozen tribes to populate. What I need to know * What traits do I need to consider when defining a tribe * How do I ensure that my tribes are not overly similar and don't appear 'flat' [Answer] Building a unique tribal group you can be done by varying some or all of the following attributes. Some of these will answer themselves (such as 'government') but others may require a little bit of inventiveness. And, as @VilleNiemi said, feel free to borrow interesting culture influences from wherever you can find them. Frankly, the richness and diversity of Africa should keep you busy for a very very long time. * artifacts * arts and recreation * clothes * customs and traditions * food * government * knowledge * language * religion * shelter * tools * values The above list of characteristics is just the basics and the list could get much longer the more one thinks about it. Keeping some of these attributes the same will maintain cohesion between tribes. Language, food and clothing are excellent candidates for keeping groups cohesive. Addressing as many cultural attributes as make sense will prevent your tribes from feeling flat. [Answer] The normal method used by authors since time immemorial is to copy them from somewhere else and modify to fit the setting and story. For tribal cultures, you can pick up data on tribal cultures in the Amazon, Africa, South East Asia, or Siberia. In these areas tribalism persisted until anthropologists had time to study the cultures. Tribal cultures are obscure enough that it will take minimal rewriting to make them unrecognizable. Very few people know anything about them anyway. So answer to your (second) question use a real world source as a model. The answer to the first is basically: Whatever your stories need... It is generally best to not be anymore detailed than is needed so that there is space to develop stories and setting. [Answer] What are those tribes all about? * Many of them will be "full-service tribes" except for a few imports, possibly including new DNA through intermarriage. They farm, they hunt, they fish, they make clothes and tools. If the terrain is similar, they probably grow similar crops and hunt similar animals, with similar tools. * There could be minor differences. Perhaps a tribe lives near a lake or the coast and uses fishing rather than hunting. A tribe uses wooden huts, another tribe uses stone buildings. And so on. * Tribes with a lifestyle that requires the same ressources could be traditional rivals, hostile to each other and fighting for the lands in between. They might emphasize their differences in culture and technology -- the herdsmen don't fish, even if they had an opportunity. But that won't go far enough to deliberately cripple their economy. Trousers or skirts, bearded or shaven, bows or slings. * A tribe might have a monopoly on some non-essentials like dyes, spices, etc. * If one tribe was notably more advanced than the others, that raises the question why they haven't conquered the others. * A few tribes might be "specialized" to provide some service to other tribes. Traders. Religious centers. Miners and ironmakers in an otherwise low-tech area. Other tribes provide food, possibly also new recruits for the tribe. [Answer] In this sort of situation then what you should do is first define a template, the baseline. You might use this as one tribe or never show it at all but that is the starting point for all your tribes. For example: * 100 people. 30 warriors/hunters, 30 wives (gatherers) 30 children, 10 elders * Totemic religion * Nomadic lifestyle visiting the same places each year * No agriculture or grazing animals etc Then for each tribe you simply choose one or more items from your template and change it. One tribe might have been influenced by outsiders and changed religion, one may keep animals and drive herds of cattle, one may have settled down, etc. [Answer] Always write their backstory from their own perspective, not an omniscient third person perspective. For example, Robin Hood's band of merry men is typically described as "a group of thieves who steal from the rich and give to the poor." However, that is a very objective third party description. To make it first person, we need to shift the verbiage. "We see our fellow men undergoing great tribulation under the oppression of the rich. While we cannot resolve this ourselves, we can make our opinion known; we make it known in the way they find most soft: their pocketbook. We take what should never have been theirs in the first place, and give it to those who suffer from their arrogance." By shifting the wording this way, not only will their actions automatically take on a more lifelike appearance, but it also leaves them room to be anything besides their stereotype. A hungry band of merry men become less merry and may keep the stolen goods themselves. A Robin Hood who succeeds at his goal, actually changing the politics for the better, does not stop at merely continuing to thieve, but transitions into a more applicable role for better instilling his beliefs within the structures of the political system. Shifting is important. Real life groups must shift to adapt to changing scenarios. When you bring these groups into your story, make sure they are given a history that looks like it shifts from a third party view, but from a first person view appears to hold the same fundamental views (just like Robin Hood adapting to a world where thieving is not needed to prove a point). [Answer] Regardless of the actual [attributes of the tribes](https://worldbuilding.stackexchange.com/a/25373/2138), there are going to be several potential starting points from which the involved tribes occupy the same area. 1. A single tribe has many off-spring. Enough so that there is an entire group of people who are not necessary for the working of that tribe, and have enough people to start their own. They could split under either good or bad terms. * The tribes who do this will have a number of similarities to start with * They will also have working relationships (either good or bad), unless one migrates out of the area for a long period of time. * As they continue to grow and split, you could end up with many similar, but not the same, tribes in family groups - each may have feuds or alliances with other families. 2. A tribe migrates into the region. This could be simply because the migrating tribe was following their food source, or it could be because of a natural disaster or other shortage in supplies, or maybe the grass is just greener here. * A migrating tribe is under a lot of pressure to find resources and provide for the tribe. Depending on their views, and the amount of hostility between them and the local tribes, will determine how the relationships turn out. (I don't have any facts on this, but I would imagine a migrating tribe entering the area is usually frowned on) * A migrating tribe is likely to have very different attributes from the ones in the area it is entering. The larger the physical distance traveled, the more likely that they are different. --- With those two types of tribes, you could imagine how a group of tribes might occupy an area and suddenly another, very foreign, tribe shows up. The foreign tribe migrated due to a disastrous storm and hurricane which pushed them out of their normal habitat, which is essentially destroyed. Seeing people in distress, the tribe who first came across them may help, and the migrating tribe might pick up some survival tactics from the natives for this new habitat, completing a friendship. However, the migrating tribe settles down nearby in a different local tribe's area. This other tribe doesn't take kindly to the strangers and is offended by their worship/fear of storm gods, so try to push them out. You can see how eventually, the migrated tribe might have officially moved in and taken over one of the other tribe's spots, yet have good relations with that first tribe who is totally different from them. You could also see how the first tribe might align with their neighbors, and the migrating tribe might be forced onto lands that can't support them - so are required to raid for their food at times. --- It's all going to come out of how the tribes split up when growing, or how they first migrated into the region. The farther back you flesh out a tribe's history, the more you'll come up with various beliefs and traits for that tribe, making it less and less flat the farther you go. It is the history and the "why" a group is the way it is, that makes it less flat. Even if, story-wise, you tell this difference via their myths or beliefs rather than explicitly stating the history. [Answer] From a sociological and historical perspective, tribes are ways for related family groups to ensure they have access to enough resources to survive in a fairly hostile environment. In richer environments, the population can grow fairly rapidly due to agriculture, making family/clan/tribe groupings somewhat less important, while the smart people organize to gather and distribute the surplus wealth of the farmers (polite way of saying "steal it for themselves so they don't have to toil on the farm"). Looking at the real world, you see that areas where tribal affiliation is still the dominant form of social organization is indeed the more marginal regions of the world, like sub saharan Africa, or Appalachia for that matter. Since the environment is hostile or marginal, it is vitally important to ensure that the people you share the environment are trusted and trustworthy. Family, clans and tribes are organizations where the trust is based on kinship and shared relationships. Even if "others" come to steal your women/cattle/resources, you can always round up brothers, cousins, nephews and other kinsmen to protect your stuff and fight to get it back, seek revenge etc. This also suggests (and is demonstrated in the real world) that tribes are suspicious of outsiders, and outside influences. Your roving band of adventurers/merchants/missionaries are going to have a rough time interacting with close knit and suspicious tribal groups, especially if they are advocating changes to traditional mores or means of doing things. In historical terms, tribes could often be turned against each other by Imperial forces with access to greater riches they could offer selected tribes (divide and rule), and tribesmen were also often coveted for their fighting and tracking prowess (Indian scouts for the US Cavalry, Ghurkas in the British Empire), so tribes can provide lots of interesting background and story material for you to work with. [Answer] ## Start with What Divides Them Why have these tribesmen not integrated with the surrounding cultures? Why have these tribesmen not integrated with each other? Once you answer those questions, a lot of other world-building info is going to just naturally fall out. ## Historical Examples The Eurasian steppe was full of nomadic horsemen - think Tartars, Mongols, Huns, Turkomen, and others. They didn't integrate with the surrounding empires or cultures at least in part because those empires were agricultural, and that live-style was at odds with nomadic herding. The nomads generally didn't integrate with each other because the herds naturally drift apart in search of forage, which places a kind of upper limit on the size of a political body. ## Choose Your Division So for the Eurasian nomads, the key division was a society built around the horse. Pick something similar - a difference that sets these tribes apart from their neighbors. Then keep asking about the implications, and looking for ways that this key issue sets them apart. All the quirks and details will flow from the source of division. [Answer] ## Think of Europe The countries of Europe are from similar backgrounds, but fight among themselves, so they're a decent model for how much you might want to differentiate your tribes. Now, imagine how you would differentiate your tribes if each of your tribes was a European country. Probably not much, until it became relevant to the story you're writing. It's hard to describe how (say) France is different from Germany or Greece. Any explicit description of the differences would be clunky and simplistic (although people try in real life, so your characters might try as well). Instead, you could explore each tribe with your characters. If your character had a list of an engineer, a musician and a farmer to meet different countries in Europe, you could convey some idea of the different countries by the way you describe each character and each meeting. You will add details as you do this (e.g. France has big concert halls or Austria has lots of street musicians) which will help characterise each place. It doesn't matter what details you choose - the future writers will pick up on what's there, and invent what isn't, as long as they are inspired by their idea of the country. Be aware that you don't need to describe all of your tribes, either. It's fine to have some tribes which you never describe in much detail (e.g. France might only ever be mentioned in connection with champagne). What makes a tribe "filler" is when you talk about it unnecessarily (e.g. listing all the tribes present at a meeting, or saying which tribe a character is from if that isn't important). ]
[Question] [ In a setting I've been working with, I sought a method of sublight travel that wasn't crazy engines or magic. I've already got FTL using a different method than the Alcubierre drive, so it wouldn't be used for this purpose. Furthermore, I postulate that the power requirements for such usage aren't attainable. ## What, if anything, changes when the Alcubierre is only used at around 10% the speed of light? Does this change at other percentages? I envisitioned the Alcubierre drive in this manner acting as a "Cruise mode" for travel within star systems. Plot your course, hit the drive and let autopilot take care of the rest. Your sensors can detect other objects in the system and you can broadcast your path so collisions can be avoided. Furthermore, emergency safeties will drop the drive before any collision would occur. Furthermore I assume that when you cease using the drive, the craft that was using it is no has a forward velocity. Clarification on this, if any would be helpful. [Answer] What changes occur at less than the speed of light? To the best of my knowledge: not much. In fact, [NASA's Alcubierre plans](http://io9.com/heres-nasas-new-design-for-a-warp-drive-ship-1588948192) explicitly involve cruising about at less than the speed of light before the main act. It's a case of not running before you can walk. Also, forward velocity is required. My understanding was that you'd need some forward velocity when using the Alcubierre. If you didn't, you'd need to move the space you are in the entire distance of your travel with you. Conservation of momentum will require you to keep that velocity when exiting warp. [Answer] The drive itself should not have any differences between speeds but still might not be practical near planets and space stations. The alcubierre drive warps spacetime so that the ship never moves relative to the 'bubble' it creates. So when the drive is switched off your velocity can be zero! This is not all good though, if you stop near a planet (which you probably are most of the time) the ship will fall toward the planet as you don't have the velocity to be able to orbit it. You would need a normal (Usual called sublight in books) drive to get your velocity high enough to be in a stable orbit around the planet. As you mentioned this would probably be automated. To dock to a space station you would want maneuvering thrusters to allow you to make the small changes needed to align with the docking port. (Also the Alcubierre drive would destory the space station if it was turned on when you approached it.) [Answer] The big difference is you don't violate causality. However, you still manipulate enough energy to destroy the star several times over (where does it come from?), and dragging the space warp around the solar system will destabilize all the orbits. ]
[Question] [ Following up on [how-might-a-religion-be-used-to-help-maintain-a-generation-ship](https://worldbuilding.stackexchange.com/questions/20908/how-might-a-religion-be-used-to-help-maintain-a-generation-ship/20913#20913) and [what-society-might-survive-the-3-generation-rule](https://worldbuilding.stackexchange.com/questions/20275/what-society-might-survive-the-3-generation-rule). Assume: * Your ship is a generation ship that has traveled to the stars. * The trip has taken ten generations (or more!) to complete. * Religion plays a crucial social engineering role in keeping the ship maintained for the flight (how it works is up to you). * The ship is nearing the end of its journey. Do not feel you must accept my interpretation of what's happening but I'll layout a scenario for you to explore. Do you begin explaining to the current crew exactly what is happening or has arriving at the destination and colonizing the planet always been part your religion? If the answer is "begin explaining/reveal the religion as social engineering": 1. When do you start? 2. With whom do you start? 3. Do you keep a portion of your religion or do you make the planetary colonization a "New Testament" addition to the original religion? 4. How do you prevent schisms? If you answer above was that this has always been part of your religion: 1. How do you pass on the necessary sciences & engineering required to begin the new colony 2. Do you plan for your religion to continue onward forever or do you plan to deconstruct it at some point with well placed hints or actual records? 3. Do you think some of the first generation crew/colonists might have planted several social bombs designed to "blow-up" the religion at some point and reveal the truth? If you think this question has become too broad, let me know what aspects bother you and I'll do some skillful pruning of the topic. If I need to prune too much, I'll cut out portions and ask another question. I figure which ever way the engineers decide to go, some portion of the crew will elect to believe the religion is not real while others will continue to believe the religion and that the reveal is heresy. If you care to do so, expand on this schism. [Answer] If you are using religion to hold your people to follow some rigid code, then the end game should be part of the religion. "We are headed toward... and when we get there... yada yada yada..." Telling them it's all made up BS before you actually land is asking for a rebellion and you might not actually finish your trip. They might pick a new destination to keep the religion from ending or being fulfilled. People really don't like to be told they've been wrong and even worse that they've been lied to for their whole lives. [Answer] > > Do you begin explaining to the current crew exactly what is happening or has arriving at the destination and colonizing the planet always been part your religion? > > > No. It's simply too much of a risk. Any planned unveiling increases the probability of an unplanned unveiling. If that happens say, halfway through the trip, it could endanger the entire generation ship and mission. > > How do you pass on the necessary sciences & engineering required to begin the new colony > > > I would design the colony ship so that the operations include/require everything that the eventual colony will need. So if it gets there, they'll by definition have the required knowledge. I don't think this is too much of a stretch. Now, maybe your farmers need to know new techniques rather than relying on hydroponics, or something of that nature. You should have that information available, and make sure the computer/AI keeps it so it doesn't get lost. Trickiest parts will be things you simply can't do in a ship, like mining. For that I'd incorporate the techniques into religious rituals - sacred foundry for coming of age, re-smelting the same "rock" over and over, etc. > > Do you plan for your religion to continue onward forever or do you plan to deconstruct it at some point with well placed hints or actual records? > > > Forever, for the same reason as my first part. It's just too risky, let it die naturally thousands of years in the future. > > Do you think some of the first generation crew/colonists might have planted several social bombs designed to "blow-up" the religion at some point and reveal the truth? > > > This is possible, and should be designed against. I would make sure that the people who "write" the religion - the ones who author the books - don't go with the ship, and are called the Prophets. That would greatly limit the ability of any first generation crew/colonists to blow things up, since they wouldn't have the same moral authority as the original authors. To hold off new prophets, make one of the original predictions be "No new prophets before the 5th generation" or something along that lines. You don't want to make your religion too rigid, but that will make it really difficult for anyone who knows it's fake to make major waves. [Answer] The question is how much help you think the colony will need as it stands up. If you think you can just abandon an infant to the woods and expect a wolf to raise it, then announcing that all they ever lived for is a lie is a totally effective approach. Far more effective would be to attempt to craft their lives to where they are less dependent on the mystical portion of your religion, and then let them decide if they want to abandon it or not. More likely they will use it highly successfully to adapt to their new climate. It also may help to tie the human civilizations together as they reach out into space again a milinia from now. As an example of a latent religion, consider Frank Herbert's Dune. The Bene Gesserit's Misionaria Protectiva seeded hundreds of planets with the barest threads of a religion. If one of their own was ever trapped on a planet, they could find protection by weaving themselves into this religion, knowing the Misionaria would provide the framework for belief. ]
[Question] [ Let us suppose that we have a non-human sentient species that has "evolved for war", i.e. has evolved significantly both biologically and sociologically from a non-sentient state such that its members consider a state of warfare as natural and right, and for there to be an absence of war as quite unnatural and merely a precursor to a new war. This species would consider any other sentient species, including itself, as a legitimate opponent in its perpetual wars. This species must be capable of organised, technological warfare, yet have sufficient restraint so that it would not cause its own demise in a Mutually Assured Destruction scenario. How could such a species evolve, and what physical and sociological traits would it need or gain as a side-effect of such evolution in order to fulfil this role? [Answer] Social insects have evolved "castes" of warriors (ants, termites, worker bees called to defend the hive etc.) which might be a template to work with. Rather than the entire species be devoted to war, they have evolved into separate castes to specialize in particular areas of work. This may have evolved because having a specialized caste of "farmers" meant that the group had more food than other, non differentiated groups, and carried on from there. Since it is always easier to "take" than to "make", it soon became imperative that a way to protect the group was found, hence the evolution of a warrior caste to protect the group. Warriors are generally larger, stronger and have more extreme fighting mechanisms than other castes (teeth, mandibles, poison sacs, stingers, whatever the evolutionary background is), better defensive mechanisms (armour plating, toughened skin, spikes or other protrusions) and enhanced senses, coupled to lightning fast reflexes. A species with a warrior caste will have some built in limitations to warfare, since the breeding and feeding of warriors takes resources away from other things. You might not have enough farmers or engineers, for example, and the society suffers. Too few warriors and you are in danger of being overcome by your enemies. So society is in a constant dynamic with various groups within the society competing for resources while also trying to strike a balance to deal with external threats. Another issue is the Warriors will generally be much "smarter" in many senses than other castes, simply because stupid soldiers get killed too easily. If there is already a ruling caste (analogous to the "Queens" of social insects), then there will be some conflict developing within societies as well. Warrior genes might be recognized as being useful (even in pre literate societies, the recognition of breeding for traits is well known), so warriors might be interbred or interbreed with the other castes to enhance the entire society. Since on Earth war is a "continuation of politics by other means", and total warfare or "war to the knife" is rare (and self limiting), we might expect that alien beings will also have evolved similar mechanisms to keep warfare under control. This could go out the window when they start going into space and meeting extraterrestrial beings, which would be seen as far outside any norm and an existential threat, upsetting the internal social order and possibly causing their society to start mass producing warriors to deal with the threat. [Answer] Consider what it means to wage war. First, one must identify a sentient entity besides yourself. Let us call it the Other, after the traditional name given to a sentient environment or portion of an environment. At all times, it must have a desire to destroy this Other, often at the risk of its own Self. However, its own sense of Self must be strong, or else it would eventually be worn down from defeat after defeat. This leads to the first psychological structure that has to be present: it needs to have enough patience to destroy the enemy while growing its Self. However, destroying sentient beings and species is hard. They adapt to the onslaught, so if the onslaught of war is not sufficient to completely obliterate a species, those that survive tend to carry with them scars that could eventually lead to the destruction of such a warlike species. Accordingly, the second psychological structure I could see would be a fanatical completeness in the destruction of the Other. Nothing must remain. Now, what happens with these two attitudes? Nothing good, that's for sure. I'm going to call the species The Hateful, and they will earn that name. The Hateful could be sexual or asexual, but the sexually reproducing case is more intriguing because it's a harder to build world. Let's play with that. The Hateful are a live-birth race. During gestation, the mother emits a chemical into the fetus' blood stream. For most of the term, it does nothing. However, at a key point in development, a brain structure forms which will be the nexus of their hate the rest of their lives. This structure is held in an undifferentiated state by the chemicals emitted by the mother. In this state, it emits neural pulses and chemical messages to the mother. The mother responds by sending her own pulses and chemicals describing her hate. She doesn't describe the object of her hate itself, for reasons we shall soon see. She, instead, directly exposes her hate, like an angry ranting and raving to the fetus. In this undifferentiated state, the special brain organ begins copying those signals, learning them carefully. At birth, the chemical stream from the mother fades. Hateful mothers watch eagerly for the passivity to leave their eyes as their brains began to focus under the clarity of the hate. The brain structure which once received hate from the mother now differentiates, forming an organ custom built to identify and destroy something hated. This is a tense time for the mother. At this phase, the child must tune their hate properly. Too little hate, and the forces within their brain cease to incentivize their heart to beat. Too much hate, and it becomes overeager, like the universe's most violent allergic reaction. In this case, even the slightest protien shared between them and their quarry will cause the child to consume itself in a hateful rage. At this point, a young Hateling is taught everything they will need to know. Despite their outer image as a destructive mindless species, the Hateful are a very intellectual race. In fact, intellect is the only truly safe way for them to interact with one another without accidentally invoking the hateful centers of the brain (with murderous results). Hateful are taught to use this intellect for one thing: to maximize their ability to destroy that which they hate. If they were not taught this, eventually their own intellect would oppose the hateful centers of their brain, and in response the brain would simply shut down their heart and lungs, just in case the intellect had gotten infected with the Other that they hate. They learn to use this intellect to build relationships. No two Hateful have exactly the same target of their hate. However, there is a mutually beneficial relationship between two Hateful if their Others' are similar. Political structures arise to scuplt and tend to the hate of the many, aligning it for interstellar warfare. A Hateful must constantly sense that they are actively fighting their enemy. This is difficult for a Hateful raised to be a farmer. It is hard to see how the bread that feeds their armies actively combats that which they hate. Accordingly, there is a gain circuit within the brains of each Hateful, with which they can control their level of sensitivity to that which they hate. Their warrior castes can leave this gain down, for the blood of their enemies is easy to see. However, if the enemy is less present, such as for a farmer, or even a warrior after the complete xenocide of their enemy, they immediately begin increasing their gain, looking for any shreds of that which they hate. If there is nothing left, this hate will consume them, leaving them desperate to find anything to hate. They may turn on their fellow warrior, simply because there is still some hated blood left on their blade, and that's sufficient to send them into a murderous rampage. Those who cannot find enough to hate are put down before they destroy all. This sounds like an evolutionary dead end with all this wanton destruction, but evolution never leaves a dead end. Sometimes, a mother fails to make contact with their unborn child before it leaves the womb. When this child's hate centers differentiate, it has no subject to hate, and one of two extremes happen. One situation is the child becomes hateful of absolutely everything. Such a creature is one of beauty to a race as hateful as this, so destruction is... wasteful. They are left to the wolves, sending them far and wide to new planets to start a new tribe of Hateful there. The other situation is more intriguing, for when it finishes raising the gain on its sensitivity to hate all the way, and still cannot find it, it instead finds something else. Something subtle and clever. This Hateful learns quick to pretend it has the hate of its comrades, but with eyes unclouded by hate, it can find other paths. The Hateful don't know it, but it is these children who are essential to their survival. These are the children which subtlety shape the intellectual discussions to ensure there is always a new subject of hate outside of the tribe. And maybe one day, they can utter the sacred words to annihilate all hate within their race... but not today. There is too much blood left to spill. [Answer] Raymond Feist has sketched such a race in the 'Dasati' featured in his [Darkwar Saga](https://en.wikipedia.org/wiki/The_Darkwar_Saga) Some tidbits from the [wiki](http://midkemia.wikia.com/wiki/Dasati): > > Religion > > > Millenia ago during their version of the Chaos Wars His Darkness the Dark God rose to supremecy & disposed all the other 10,000 Gods of the Dasati. He twisted them & turned them into the nation of fierce implacable warriors they are who worship death. He is served by his Deathpriests and Heirophants who keep the people devout and search for any sign of rebellion. > > > The Hiding > > > When Dasati women become pregnant they go into Hiding as their children would be viewed as a threat by Dasati males who would see them as one day becoming a threat to their offspring. Males remain in hiding with their Mother until they reach puberty & start to become violent, at this time they are sent to their Father's estates, During the Hiding women and children only come out at night for safety. > > > [Answer] citing nature: There would be violence in every level of society. So much so, I'd argue that there would be almost no nation-scale warfare. Every few generations, maybe a major conflict occurs, but by and large it would be nearly impossible for a group to establish dominance over more than a couple of other groups at a time. And even then there would be so much infighting, they would likely destroy themselves. Interestingly enough, any sort of governance which is permissible would be trim, responsive, and highly effective. They would be temporary and probably only arise to tackle a single issue, then dissolve away so members can resume fighting. Humans societies are rot with rabid corruption and absurd bureaucratic labyrinths because of lazy, docile populations. By contrast, the warrior society would need no law, and no constitution but a supreme sense of honor and justice in-which everyone is eager to participate and enforce. Unless they're all mindless drones. A child born would either exemplify the maximum genealogical abilities, or be culled from the family. If the former, they are groomed for combat and trained by a tight nit the family/clan. Else, they are either terminated, exiled, or made to perform menial labor. Or used to inflate the ranks. Your society must be supremely stratified. In lieu of being truly mortal, conflict most often used to establish submission/dominance. Those who lack the strength or whits to fight for themselves will be allowed to live only as slaves. There is also the possibility of some form of 'royal syrup' used to prepare young. Without this syrup, a child would grow up dumb and brutish and utterly submissive. With it, they rule absolutely. You might need something like this to account for the mass-stupidity required to fill your infantry. I'd argue against some other points raised by this question. Most humans share their resources rather openly and are accepting of others. I'd say throughout our history we've been mostly exceedingly peaceful and respectful of others. It's just, people like to be dazzled with tales of the exploits and explosions of war and so the most popular subjects of history are warfare. If we were truly violent (beyond the few thousand shameful years of 'civilized' history), we would have selected more serious natural defensive mechanisms. Claws, horns, fangs, stingers, scales, camouflage, something! Instead, look at these meat-slugs! I'm all soft, fleshy and pink! Before the great leviathans of history, there was no need to compete for resources because the natural world was full of food and water. Most fighting would have likely been personal. Truly Self-Violent species tend to have higher degrees of sexual dimorphism. Another proof for the lack of pre-historic mass-violence in humans, is the fact that women and men appear roughly the same size because for millions of years women have been selecting men who would share the responsibility of rearing young. Your species is likely to have one sex dominant over the other (could be either) as the most desirable traits exemplify dominance. Rhesus Monkey live fairly despotic and males are 30% larger than females. Extreme examples include bee and ant colonies. If you want a surefire way to ramp up the shear scale of your conflicts, I'd consider a species which organizes as doth the hive. Gene-pools are probably isolated and insulated, and you probably have a few populations fully speciate (spelling?) with some major differences cross-species. A hive society would fill their infantry ranks with mules and drones. Don't be fooled by the title given the 'queen' bee. She is actually ONLY slave in the hive. If her egg production slows, the drones will produce royal syrup and feed it to larva in secret so they can produce a new, better queen and kill the old. Actual warfare usually occurs as a result of an expanding population amidst limited, irreplaceable resources(the case of the yeast colony). The development of modern nations is exceedingly a violent endeavor, but no conflict occurs where there is not profit and plunder to be had. And even then the conflict eventually ends. For an enduring conflict, your spices would not be 'resolving' a boarder or legal dispute, or securing resources. If the reason for such violence is not it is not part of the courtship ritual, you'd be hard-pressed to discover a truly convincing McGuffin. unless they're all crazy. [Answer] To help prevent the Assured mutual destruction, I think that the 'war' would be much more focused on individual combat skills. Whether the killing is done with hands, a sword, a gun, or even an airplane dog fighting, the wars are for warriors. So things like bombs might be seriously discouraged or scoffed at. Anyone can kill with a bomb, you don't even have to be there for it to work. But a swordsman who can lay out 12 enemies is a great warrior, or a pilot that has shot down 20 enemy planes is a hero for the songs. This of course would require a little of Japanese Samarii type honor, where some things just are not done. edit: Also the species would have to breed numerously, which might both encourage competition and keep their numbers up. With a fast healing rate this might also encourage aggressive behavior, if taking a sword through the guts is not likely to put you in the grave but only keep you off your feet for a week, then less reason to back off. These two traits would be needed to keep the species from killing itself off. Lots of young, maybe litters, and very tough to kill or permanently maim. [Answer] To go the whole human route... What if the species had more of what humans have? Rather than making them an incredibly powerful, martial-based warrior race of he-men, what if they were instead a race of incredibly intelligent, cunning and vicious murderers? This race would essentially evolve initially very similarly to humanity, using intelligence and tools to overcome their physical shortcomings. However, their technological growth would outpace humanity tenfold. The kicker to this would be that their cultural growth would not - they are simply more intelligent, not more refined. Their 'Romans' would chase out the barbarians with the Julius-IV Main Battle Tank, their feudal lords would be bombing each other with drone strikes, their renaissance would be the development of space travel. The reason they would be so warlike? Because they can't stand each other, and their increased intelligence makes them want to constantly prove that. The reason they don't destroy themselves in the process? They're smart enough to see how that would be a bad idea. TL;DR: Super-intelligent humans. [Answer] First, war is something that happens between groups, "us" and "them", or "good" and "evil". So there is no particular reason to think that a warlike species would be more violent or less emphatic within its own group. If anything they would probably value their family and children more than species not in the constant state of war. After all they would need constant mutual protection to survive. Friends and relatives would highly valued for the mutual assistance in survival. For that matter unless you can trust your comrades and be loyal to them, you will not be much use in war at a species level. A sniper or similar type can be highly effective in even modern settings without teamwork, but for the bulk of warfare good team players are wanted. These might imply strong family bond and maybe a cultural code of honour that stresses loyalty to your family and comrades. Something like: "Stand together, fall alone"? Group succeeds, individuals fail. People would dislike being alone and avoid individual responsibility. They would also dislike leaving anyone alone or not helping share responsibility. Or any other burden. So to their own group they would be gregarious, helpful, and steadfastly loyal. Singing and dancing accompanied by good food and drink might be involved. What would set them apart from humans would be a inbuilt xenophobia that prevents peaceful interaction with other groups. People would simply not be able to trust other groups enough to have trade or share territory even temporarily. They would not even expect betrayal since there would be no trust to betray in the first place. Any interaction would end up with violent confrontation by default. This does not necessarily imply fighting to the death or even any fighting as people would be good at estimating the relative strength of the groups and the weaker group would retreat until the stronger one would stop pursuit. After all usually if the pursuit goes on long enough the retreating party has control of where and when any engagements happen, which can be very dangerous for the pursuers. Note that even defeated foes would not necessarily be killed as slavery would probably be normal. Otherwise lack of peaceful interaction between groups would result in loss of genetic diversity and surplus of genetic disease. Having the defeated embedded in the victorious group as property solves this issue. And this type of slavery was historically common. At higher technology levels this would also allow ideas and inventions to spread between groups and enable social evolution. Social evolution would probably follow similar lines as with humans family groups would grow to tribal chiefdoms for better defense. With invention of agriculture kingdoms with organized religions and divine mandate would be created. With better communications and transport the size of kingdoms would grow. Maybe you'd even get nation states. History would be quite different as people would see no value in having neighbouring states. Any such that could be destroyed would be destroyed. So you'd have kingdoms that are as large as possible along the natural borders of the geography. The balance of power between nomads and civilization would also be different. Groups such as the Huns or the Mongols were really alliances of many tribes. Depending on the level of the genetic xenophobia this might be impossible. There might still be large nations of nomads, but they would grow gradually and be civilized as they grow and capture slaves and territory from their civilized neighbours. [Answer] Alien options are a the bottom. > > Let us suppose that we have a non-human sentient species that has > "evolved for war", i.e. has evolved significantly both biologically > and sociologically from a non-sentient state such that its members > consider a state of warfare as natural and right, *and for there to be > an absence of war as quite unnatural and merely a precursor to a new > war.* > > > You'd pretty much have human beings. Prior to civilization and specialization of labor, all men were warrior and human-to-human violence was the major cause of male death. As civilizations formed, warriors seemed to become a specialized caste but in reality that was just because it took a huge number of workers (tail or shaft) to support the military head (teeth or spearpoint.) The highest status individuals in all major cultures were warriors and warfare considered the most morally pure endeavor. Consider the origins of the worlds, villain, vile and noble as they apply to morality. The first two come the latin 'vil' as in village and mean "farmer" the last comes from the latin for "famous name" and the 'nobel' of the West and the rest of the world were a caste of killers whose males trained from infancy for killing. Probably half the wars in history were fought for glory just because the "nobles" didn't have a purpose without war. Now consider that the words for farmer mean evil and disgusting and the word for the killers means the most moral and you can see just how great a role war played in the past. All other major languages have similar evolutions. The idea of world without war does not seem to ever popped up until less than 300 years ago in northern Europe. That's when war began to be seen as the anomaly instead of normal. What we think of as a normal moral attitude is a very, very recent cultural invention. Ethical universalism, seeing all human beings as morally equal who should be treated the same, is really less than 200 years old in the west, imperfect even here, and spreading only slowly across the world as advancing technology requires wider and wider degrees of cooperations. Jerry Pournelle's once observed that, "Peace is an ideal whose existence we infer from the fact there are intervals between wars." Likely, that is because prior to evolution of the corporation, large scale, long distance trade and technological progress, productivity changes only over the course of centuries. If anyone from individuals to people's wanted to improve their lot, their only option was to grab some of what somebody else had, land, food, minerals, population etc. Heck, before capitalism, investing and stock ownership, the only way to get anything major built was by collecting taxes at sword point. Given that all social mammals and insects fight collective combats that we could call wars, and that includes social apes, humans likely evolved from fighting primates. The same rules of evolution would apply on other worlds. --- ## The aliens The only big difference we could imagine for a alien species would be physiological. Humans have no fangs or claws because of neoteny, the retaining of fetal characteristics. Likely, this is because our upright posture is the original posture of primate fetus. Neoteny probably helps with brain growth as well. But other sentient species might follow another path. Humans can't have muzzles or fangs because we need our mouths to talk but it a species used their nostrils and sinuses to make sounds, then they could retain muzzles and fangs. Claws could be retained as long as they didn't retard grasping or helped it. Or they might take other forms. Could be anything as long it didn't get in the way of their becoming tool users able to organize on vast scales. Since it's not necessary to evoke a particular impulse to war beyond what humans and other earth animals display, we don't need to assume that just because a species retained fangs and claws and whatnot that the mathematical logic of MAD would not work for them as well. The real problem in making a space fairing conquering people is the economics. Once you've got enough energy to get into space, you've got enough energy to harvest all the material resources any planet could ever need. To make a species compulsively warlike, they'd have to have a frozen technology and no productivity growth just like humans had in the pre-corporate era. They would have to have lost the idea that make a new resource and instead just keep trying to get more of the old just like pre-corporate humans never thought of making their own land grow more food but just of grabbing more land. Some options: ### Precursor technology jumps them past the corporate/scientific/industrial era. Before they develop the idea of progress, mass trade or resource creation they stumble across starships and weapons whose operation they do not understand. The advanced weapons might be AI with no will of their own so they just take orders from the first sentient that finds them. Our aliens just use the starships and weapons to extend their pattern of conquest to other worlds, never understanding they could harvest much greater riches at any random asteroid. Note: The precursors could be their own ancestors who reached the stars then blew themselves up leaving only cave man survivors back on the home world to find bits and pieces of the old tech that still works. ### Science forgotten, technology becomes ritual In Jerry Jerry Pournelle's and Larry Nivens' Condominium series of the 1970s, the US and USSR become more worried about the spread of nuclear weapons and the destabilizing effects of advancing technology so they shut down most scientific research and contaminate scientific databases with bad data bring technological and scientific process to halt. Fortunately, this happened just after the invention of space travel. Our aliens could do something similar but more extreme and off longer duration until they forgot science existed and their technology was produced and utilized by rote passed down as rituals through the generations. Again, with no progress and no ability to create new resources, they can only conquer. ### Reavers take over At some point, after the society becomes star faring, they decide to undergo a species wide genetic engineering program to make them incapable of aggression. But, some back-to-nature/primativist-cult that idealizes the old days of incessant war and hides out to avoid the transformation. When everyone else is rendered passive, they come out, and under the principle of "in the land of the blind, the one eyed man is king," take over and enslave the others, forcing them to create and maintain the technology they use to fight pointless wars of glory just because they think its what their species does. ### Bored post-singularity hold-out, game players Most of the population passes through the singularity and takes forms unidentifiable to pre-singularity beings. But some don't choose to do so but they've hit an advancement ceiling. What now? What do they have to do but loll around and play games. What happens to their society when natural competition for status breaks out into civil war. Much better to direct that bored frustration against other species. Since they can't progress technologically and they might usually run into technologically inferior species, they make it a game, intentionally downgrading their technology to match their opponents to make it fair. Their entire culture would be based on seeking glory in war, regardless of how those wars are fought. Maybe they'd destroy or corrupt all the nuclear weapons on a world just to keep things going longer. ### Crusader/Jihadist The aliens encountered are on a mission to wipe out any competing species before they become a threat to home world species. The warriors encountered are far, far from home and not equipped with the latest and greatest technology. They don't conquer but exterminate. Some thing like Fred Saberhagen's berserkers, but subculture of biological organisms instead of robots. [Answer] I'm thinking that if you had two sentient species evolving together, you may be able to develop the necessary conditions pretty easily. Say you had one species occupying the temperate region of the planet and the other species occupying the remainder of the planet. This imbalance could lead your marginalized species to develop a culture somewhat similar to the Viking raiders, basing a large part of their culture on pillaging the other species. You'll probably need to give your marginalized species a physical edge to keep them from being wiped out by the better fed and likely more numerous temperate zone species. You'll also want your marginalized species powerful, but not powerful enough to take over. [Answer] In the vast majority of cases, species tend to evolve away from war, not towards it. Take the case of sexual competition, where animals compete with each other for mates. In almost all known animals, the fighting does not consist of all-out warfare, but rather subdued shows of force. A good example of this can be seen in lions fighting with sheathed claws when competing for dominance. Why do they not fight all out, when so much is at stake? This can be analysed using game theory. In most cases, fighting is a mutually destructive action, and despite the high rewards of winning, losing has penalties which are almost as large if all out warfare occurred. Therefore, there is little reason to "evolve for war" as such a species would tend to encounter mostly members of its own species and are genetically related, and is therefore more likely to reduce its own fitness by warring within its own genetic group. ]
[Question] [ With modern technology, targeting equipment has become very good in its ability to pick out a target and lock onto it, thereby reducing the viability of traditional camouflage. In a world of mechs, this technology has increased in power and accuracy, primarily against large signals like vehichles. The issue with this however is that the equipment required to perform this level of targeting is specialist and not everyone will have access to it. Visually spotting a mech target is still a requirement even with the technology. The mechs themselves are big, around 5 meters at the smallest. They are often deployed in combat hotspots including deserts and rainforests and have the appropriate camouflage pattern painted on them. They will usually carry advanced targeting computers that can track multiple targets and objectives simultaneously whilst tracking for more contacts. This operates mostly on heat signatures but can also catch the occasional communication signal from hostile targets. What I want to know is will camouflage in the traditional sense be made redundant in its entirety or is there still a viable place for it on the battlefield. Likewise, is there much room for improvement within the combat zones outlined using camouflage techniques that can disrupt radar or make it harder to spot? Would [this](http://www.google.co.uk/search?q=battleship%20camouflage&es_sm=122&source=lnms&tbm=isch&sa=X&ei=H72CVYzPAYWy-AG-sYDwDQ&ved=0CAcQ_AUoAQ&biw=1440&bih=799 "this") be useful in these scenarios? [Answer] The most probable development for future camouflage (for all combat elements, not just mechs) would be metamaterials. Metamaterials are structured in such a way as to deflect waves around then in non classical patterns. There are actually many different ways of doing this, but the optical lattice is the most commonly used and understood. Essentially, an optical lattice is a structure with gaps that are a fraction of the size of the wavelength that you want to manipulate, with the gaps engineered to "bend" the light in the direction you want it to go. In theory (and now in practice) you can bend the incoming wavefront to "flow" around the object being protected so there is no reflection or refraction to indicate the object is even there. Since the waves flow around it, there is no "hole" to indicate its presence either. Current metamaterials work in the electromagnetic spectrum (radar and microwaves), and in limited optical frequencies (usually one or a small number of frequencies). Metamaterials can also be scaled to deflect sound waves; reducing the ability of sonar to track ships and submarines. Very long wavelengths, like the ground waves of earthquakes and explosions could also be deflected around buildings and structures: a metamaterial shield on that scale would look like a grid of pilings driven into the ground around the protected structure. Metamaterials are passive, which means the operator doesn't need to monitor or activate anything, but based on their nature, they will require lots of care and cleaning to remain functional, so a tank or armoured vehicle bashing through the woods or in urban combat could reveal itself as the covering becomes damaged. Metamaterials can be used for other purposes. Bending waves can be used to increase the sensitivity of antenna and optical components of cameras and sensors by focusing the incoming waves to the receiver. Laser and microwave emitters could also be vastly improved by using metamaterials rather than lenses to focus the beam. Metamaterials are not a cure all, however. The heat energy of the vehicle or soldier still needs to be managed somehow, and the use of energy (sending a radio transmission or using a weapon) will also reveal that something is there. The vibration of a moving vehicle can be picked up by geophones, and metamaterials themselves are designed around specific frequencies: an optical metamaterial shield would have little effect on radar, while submarines sheathed in sonar cloaks would still be visible on the surface. And vehicles in space would be revealed by their heat signature against the cold backdrop. Targeting in an age where metamaterials are common would involve large numbers of multispectral sensors employed in a "grid" to identify anomalies and direct probing fire to reveal what is there. Area weapons like thermobarics, large bombs and fuel air explosives would also make a comeback to ensure that whatever was in the target grid was actually hit. [Answer] If visual acquisition is a requirement then yes, absolutely traditional camouflage will be a requirement. A system like [BAE's Adaptiv](https://www.youtube.com/watch?v=YqJEaY_fe54) that can do both visible and IR adaptation would absolutely kill in this situation. Since radar depends on the return signal, a radar absorbent coating similar to that found on stealth aircraft would help a lot. Visual acquisition limits the engagement range to 2 or 3 miles. That's incredibly close quarters for a machine with the damage projection capabilities that a mech typically has. Dazzle is amazing and as much as I love it, I don't think it's appropriate for for the purpose of concealing a mech. Dazzle was designed to make it really hard for U-boat captains to get an accurate fix on the direction and speed of a ship given that a paint job that would effectively conceal a ship under one set of atmospheric conditions would make it stick out like a sore thumb at a different time. Torpedoes in WWI and WW2 were optically launched. The invention of sonar guided torpedoes immediately made Dazzle obsolete. Putting Dazzle on a mech would just make it easier to pick them out. There could be a psychological gain from a Dazzle paintjob much like warpaint on human warriors but that's outside the scope of your question. [Answer] Camouflage would absolutely still matter. If not everyone is in one of these 'mechs then not everyone will have access to the advanced targeting systems, and would still rely heavily on visual contact. For the record however, modern target acquisition systems use far more advanced methods than simple heat signatures, as we learned long ago how to mask those [even on the biggest tanks](https://en.wikipedia.org/?title=M1_Abrams#Concealment). On another note, as it stands with current technology (and foreseeable future tech), non-network wireless communications are nearly impossible to pinpoint without the target being within a sophisticated sensor grid. Target acquisition in advanced systems these days relies heavily on visual identification and pattern recognition. For example, even civilians have access to highly accurate pattern recognition software that can [pick out a face in a crowd](http://www.facefirst.com/) with startling speed. That's the kind of thing that the camouflage of the future will need to combat, and it will probably require [some pretty crazy materials](https://en.wikipedia.org/wiki/Metamaterial#Cloaking_devices) to make it happen. Also of note is that there's [plenty of room for improvement](http://www.slate.com/articles/health_and_science/science/2012/07/camouflage_problems_in_the_army_the_ucp_and_the_future_of_digital_camo_.html) even in current camouflage techniques. Most military organizations try to standardize camo as much as possible so they don't have to issue ten sets of it to all their troops for different environments, but that leads to inefficiencies within those individual environments where other patterns or color palates would be more effective. I guess to sum it up, camo as we see it today wouldn't undergo a radical shift because human visual identification would still be a large factor. Camo patterns on a 'mech would be somewhat different from those on a soldier just because of the size and materials involved (I'm betting your 'mechs aren't made of cloth), and you can certainly get a little creative with how you approach it like using patterns inspired by the ship designs you linked or those of modern tanks, but it wouldn't necessarily be radically different. If the 'mechs are really really tall (taller than trees) and you're mostly worried about ground threats, the tops of them might be painted more grey-blue to blend in with the sky, but then you're vulnerable to aerial surveillance. Again though, it depends on the environment. ]
[Question] [ I'm starting a whole new planet for a story and would like it to have an orange sky during the day. At a basic level (I am not a smart man) what chemical composition would be most conducive to Orange sky colouring? What colour would that appear during sunrise/sunset (Our blue turns orange due to some science magic, what effect would this same process have on an Orange atmosphere? The air doesn't have to be breathable, I am fine with whatever implications this will have on human characters re: Breathing gear, space suits, etc. [Answer] Mars has a CO2 atmosphere, which is not orange but a reddish-brown similar to its surface. CO2 is fairly nonreactive, so there aren't a lot of questions about "what would X material do". The biggest difference is that things wouldn't burn, and metal wouldn't rust. But it's not exactly orange, and nonreactivity is BOOO-RING. If you want something that's really orange, I would go for bromine. It exists as a liquid under normal conditions, but easily evaporates like water, so an atmosphere of it is reasonable. It is also very nasty stuff. It is a halogen in the same family as chlorine and fluorine, which means it [reacts violently](http://www.youtube.com/watch?v=uCwHzTsx5yY) with most metals. It also tends to attack organic materials by [replacing the hydrogen](http://en.wikipedia.org/wiki/Halogenation). These properties would make for an interesting space suit design challenge. One other thing to consider is that bromine gas is not transparent, so at the bottom of an atmosphere it could get very dark. As for sunrise and set, they are ruled by [Rayleigh Scattering](http://en.wikipedia.org/wiki/Rayleigh_scattering), the same process that makes the sky blue, and that would still be true with either CO2 or bromine. I would expect even deeper reds and oranges in either case, and no blues because blue light would be absorbed. You would need large molecules similar in size to visible light (400-750 nanometers) to get a different type of scattering, while most gas molecules are a few tenths of a nanometer. [Answer] The skies of Earth turn a red colour during sunsets as the sunlight passes through longer light paths in the atmosphere before reaching your eye, which means most of the shorter wavelengths are being absorbed by the air before reaching you. This suggests that rather than a normal planet, you are on a tidally locked planet circling red dwarf star, and are somewhere between the 45 degree latitude mark and the twilight equator (with the Hot Pole being the 0 degree mark and the sun directly overhead). During the 1960's and early 1970's, sunsets were often "enhanced" by the pollutants that were routinely released in the air, especially oxides of nitrogen and sulphur. If these elements were in the atmosphere due to natural processes or human activity, your permanent "sunset" on the red dwarf world would also be more colourful. [Answer] Nitrogen dioxide. Hella poisonous and brown orangey. And making an atmosphere of it is pretty easy, set off a nova or other powerful gamma ray source near earth or another similarly atmosphered body. The gamma rays will tear apart the o2 and n2 our atmosphere is made of and it will recombine into the more favorable NO2. An atnosohere of this would likely mean your planet was likely earthlike at some point. ]
[Question] [ What underground, for example burrowing or tunnelling creatures on earth, have underground organisation/societies, that are intricate enough for interesting narrative features, for example friendships or self expression? Worms for example have no society at all, and are no good. They may be unfamiliar, or even without analogies, to human culture. [Answer] Well you could use these: * [Meerkats](http://en.wikipedia.org/wiki/Meerkat) > > Meerkats are small burrowing animals, living in large underground > networks with multiple entrances which they leave only during the day. > They are very social, living in colonies averaging 20–30 members. > Animals in the same group regularly groom each other to strengthen > social bonds. > > > Meerkats demonstrate altruistic behavior within their colonies; one or > more meerkats stand sentry, while others are foraging or playing, to > warn them of approaching dangers. > > > Meerkats also babysit the young in the group > > > Meerkats are also known to share their burrow with the [Yellow Mongoose](http://en.wikipedia.org/wiki/Yellow_mongoose) > and [ground squirrel](http://en.wikipedia.org/wiki/Ground_squirrel), species with which they do not compete for > resources. > > > These creatures even had their own [show](http://www.meerkatmanor.co.uk/), based on their society and personality. So they would be possibly be a good fit. The squirrels and Mongoose don't really live alone in networking burrows. * [Naked Mole Rats](http://en.wikipedia.org/wiki/Naked_mole-rat#Ecology_and_behavior) > > The tunnel systems built by naked mole-rats can stretch up to three to > five kilometres (2–3 mi) in cumulative length. > > > The naked mole-rat is the first mammal discovered to exhibit > [eusociality](http://en.wikipedia.org/wiki/Eusociality). This eusocial structure is similar to that found in ants, > termites, and some bees and wasp > > > By evidence of their [workers](http://en.wikipedia.org/wiki/Naked_mole-rat#Workers) these creatures have a pretty social atmosphere and caste system. * [Ants](http://en.wikipedia.org/wiki/Ant) > > Some species (such as Tetramorium caespitum) attack and take over > neighbouring ant colonies. Others are less expansionist, but just as > aggressive; they invade colonies to steal eggs or larvae, which they > either eat or raise as workers or slaves. > > > Not all ants have the same kind of societies. The Australian bulldog > ants are among the biggest and most basal of ants. Like virtually all > ants, they are eusocial, but their social behaviour is poorly > developed compared to other species. > > > So a story featuring the different types of ants would be interesting. * [Termites](http://en.wikipedia.org/wiki/Termite#Social_organization) > > Worker termites undertake the labors of foraging, food storage, brood > and nest maintenance, and some defense duties in certain species. > > > The soldier caste has anatomical and behavioural specializations, > providing strength and armour which are primarily useful against ant > attack. The proportion of soldiers within a colony varies both within > and among species. > > > * [Prairie Dogs](http://en.wikipedia.org/wiki/Prairie_dog) > > Highly social, prairie dogs live in large colonies or "towns" – > collections of prairie dog families that can span hundreds of acres. > The prairie dog family groups are the most basic units of its > society.[7](http://en.wikipedia.org/wiki/Naked_mole-rat#Workers) Members of a family group inhabit the same territory > > > A prairie dog town may contain 15–26 family groups.[7](http://en.wikipedia.org/wiki/Naked_mole-rat#Workers) There may also > be subgroups within a town, called "wards", which are separated by a > physical barrier. Family groups exist within these wards. Most prairie > dog family groups are made up of one adult breeding male, two to three > adult females and one to two male offspring and one to two female > offspring. > > > * Even some birds [burrow](http://en.wikipedia.org/wiki/Burrow). I can't seem to find a better example at the moment, but here is something: [Burrowing owl](http://en.wikipedia.org/wiki/Burrowing_owl) > > Burrowing owls can be found in grasslands, rangelands, agricultural > areas, deserts, or any other open dry area with low vegetation.[2](http://en.wikipedia.org/wiki/Yellow_mongoose) > They nest and roost in burrows, such as those excavated by prairie > dogs (Cynomys spp.). > > > --- Not really answers, but still notable: * [Rats](http://en.wikipedia.org/wiki/Rat#Fiction) and mice have been depicted as burrowing animals and just depicted in fiction in general. [Answer] Here's a few I can think of * [Naked Mole Rats](http://en.wikipedia.org/wiki/Naked_mole-rat) * Prarie Dogs * Meerkats * Ants * Termites I linked Naked Mole Rats because they're probably the most interesting (and crazy!) They're like the ants of mammals. They have a "queen" who is the only female allowed to breed. They have weird adaptations allowing them to dig while breathing underground. They're resistant to cancer. They have social classes. Prarie dogs and Meerkats are similar but spend more time aboveground. Some Ant and Termite colonies have very intricate social structures. Some even have "prisons" and "farms!" ]
[Question] [ Could life originate on planets outside the [circumstellar habitable zone (CHZ)](http://en.wikipedia.org/wiki/Circumstellar_habitable_zone) where there is very little exposure to sun (like Uranus). If so what kind of energy source would they depend on. Could more complex life (than bacteria ) evolve on such planets? [Answer] There are theories ([here](http://www.space.com/26905-jupiter-moon-europa-alien-life.html) for example) that life could exist on moons within our solar system! Jupiter's moon Europa is a ball of ice, specifically water ice. Even more incredible is that, beneath the surface, there is apparently a massive ocean of water. The belief is that the moon is constantly pulled and stretched by Jupiter's gravity, resulting in geothermal energy that warms the core, and by extension the oceans, of the moon. We don't fully understand what causes life to begin yet, but if all it takes is organic compounds in water, and Earth could do it, why not Europa? By extension, what about something larger than the Earth with enough geothermal activity to heat its own oceans beneath layers of ice? Same idea, just no Jupiter. If it's an ocean heated by geothermal activity, there's likely no sunlight getting through the ice, so no plants as we know them, but microscopic life could exist. It could, perhaps, evolve beyond that as well! In our own oceans, hydrothermal vents have all sorts of life growing around them that feeds on the minerals rising up from their depths, even if it's very simple fauna. [Answer] The Answer is likely yes for some kind of life, if there is enough energy. There are whole colonies at the bottom of the ocean floor that live off [thermal vents](http://en.wikipedia.org/wiki/Hydrothermal_vent), no solar there at all. So if there is enough energy coming from a molten core and the other needs fall into line, liquid (most likely water) and nutrient chemicals to build a life form. Getting much past lichen or algae level life would most likely take a lot of coincidences, but it is still theoretically possible. The more likely scenario would be a planet with life that gets moved, either it's sun collapses and now the planet is outside the sweet spot or some cosmic event pushes it out, and life as to readapt as best as it can in the new conditions. [Answer] Life would have to originate within an environment which it could survive. Life that operates within a liquid water medium like us would only be able to occur in an environment where water can be liquid. Keeping water liquid by solar radiation, and water based life are not the only options though. Radioactivity, tidal forces (for a moon of a gas giant), or residual energy from the formation of the planet might provide the heat to melt water. This is not as good of an environment for life, at least as we are familiar with it, as solar heated open water, but that may be bias on our part as life that developed in solar heated water. Life could also develop to not use liquid water. Ammonia is the most often cited alternative. Liquid Methane might also work. I think ammonia tends to break down in high frequency light which limits what kinds of stars can have planets with enough ammonia. [Answer] Planets far outside the habitable zone can indeed have liquid water and therefore the possibility of life (like our own). The key thing the planet needs is a thermal "blanket" to hold in heat. One possibility is a layer of ice, as on Europa, which would need to be at least a few km thick. Alternately, an atmosphere of at least 10 bars of hydrogen can do the trick. It's entirely plausible that life-bearing conditions could be maintained even in the extreme case of planets with no stars! These free-floating planets are likely to be extremely abundant in the Galaxy. The only possible sources of heat on these planets are 1) leftover heat from formation, 2) radioactive decay of long-lived isotopes like Uranium, and 3) in some lucky cases, tidal heat from interactions with another planet (in the case of a free-floating pair of bodies, like a Jupiter with an Earth-like moon or two Earths orbiting each other). See here for details: <https://aeon.co/essays/could-we-make-our-home-on-a-rogue-planet-without-a-sun> <https://planetplanet.net/2015/06/04/real-life-sci-fi-world-8-the-free-floating-earth/> Of course, this is what such a planet would look like (from up close): [![enter image description here](https://i.stack.imgur.com/gZrRB.jpg)](https://i.stack.imgur.com/gZrRB.jpg) And from the surface, you could never see the stars (through the ice or thick atmosphere)! ]
[Question] [ What characteristics of society/culture might change if we would not have developed social media? or, if we had developed it, but it was somehow not as addictive as it is... * Would this generation's teens be as self-absorbed/narcissistic? * Would society be more moral? * Teens today are very aware of world events and global issues. Would this still be the case without social media? * Anything else major? Assume television and Internet remain as they are now, besides for the social networks [Answer] > > or, if we had developed it, but it was somehow not as addictive as it is... > > > Are you implying that social activities prior to social media wasn't addictive? It's more ubiquitous yes, but rumour and gossip of previous society is no less addictive. What can I say, humans like drama. > > Would this generation's teens be as self-absorbed/narcissistic? > > > Every generation seems to ask this about the next generations teens...why don't you malted loving teens get off my lawn? Perhaps the correct question here is would our generations perception of the next generation of teens be as self-absorbed/narcissistic without social media, or would we find another culprit to blame? > > Would society be more moral? > > > Less Moral, more blissfully blind. I would suggest the development of a global 'eye' that is the collective watching of the globe by itself through social media's has created a much more moral world, despite the perception. Take Ray Rice and the NFL on spousal abuse...are we saying prior to Ray Rice it's never happened, or we've never seen it/caught it on tape for all to see prior and even if we did, we lacked the technology to allow millions of views in under a day? I'd say more instances of immoral acts brought to light is a sign of a reduction of those acts as we are seeing them much more readily than we ever had before, not because it's suddenly happening now. A CEO was recently canned for a video of him kicking a small dog surfaced. Is this a sign of less Morality or a sign of the ever growing eye?...the fact that we are seeing them, in huge part due to social media, doesn't mean it happens more often. Teens committed suicide from teen bullying in the past, but never before has it become a social phenomenon that so many are aware of. > > Teens today are very aware of world events and global issues. Would this still be the case without social media? > > > Yes and no. Teens are more aware of peoples opinions of world events and issues, debatable if that translates to actual awareness. Peoples willingness to research and learn global issues is pretty independent of social media, although social media does increase the availability of topics for people to look further into. > > Anything else major? > > > Easier to control media. Before social media, 90-95% of media (radio, tv, written) was controlled by a very narrow band of people. Social media has brought about a rise of independent media (by allowing anyone to be a news source had they wanted), which has greatly reduced the blinders that single ownership media was starting to enforce. Back to the statement of morality...evil shit was much more easy to conceal prior to social media. If we define the stack exchange network as addictive social media, then this conversation would never had occured either. Editing from Michael's comment: I have to strongly agree that Social media has brought forth a stronger generation of programmers deeply linked in a manner many of them feel comfortable in where they would have previously faced barriers in communication. Programmers tend to be notoriously introverted and sharing of ideas and problems wasn't as frequent as it could have been...now there is a ready line of communication between them. Technological advances, particularly in programming on SE, is a very strong example of what social media's can accomplish. To go one step further...I've been watching dancing with the Stars and saw a piece on one of the people there, Bethany. If you search dancing with the... into google, it actually auto completes to her name as the first hit. She was the ultimate in introvert...as a child at school, she would answer questions directed to her by whispering to her mother and having her speak for her. These tendencies continued, until she started her own you-tube channel...a media where she could express herself freely. 4 years later, her u-tube channel ranks among the highest subscribed channels and is now a recognized name in over a million households. The classic 'American dream' lost to introverts is now a very possible reality. [Answer] In all honesty I would say take a look at the 1980's to early 1990's. (or any time before social media bloomed, just 80's/90's was closest technologically). Society has never been as 'moral' as it was purported to be in the past, nor is it more 'degenerate' now than in the past. Teens being narcissistic vs. world wise are things that ebb and flow. I think narcissism tends to follow 'rich' times and indulgent parents, and world aware lean times or periods of national stress. ]
[Question] [ I'm designing an alien species roughly based on starfish. Starfish in the real world don't have brains or blood, they just let seawater run their nervous and circulatory systems, but I figure a species of any intelligence would need an actual brain. I'm wondering if it would be possible to have a brain that isn't a solid structure but a sort of cerebral fluid in which neurons mingle to form thought. Is that an even slightly viable evolutionary strategy? [Answer] In terrestrial biology, brains work by having many neurons, each with many connections to other neurons. It is thought that the particular number and position of the connections between neurons - the synapses - affect the operation of the network and allow learning. The consequence of this is that each neuron exists in a relatively fixed spatial arrangement with other neurons, which enforces a degree of solidity. If we were to have a liquid brain, in which its constituent cells existed in a fluid and were capable of moving past and around each-other, it would be difficult to form any long-term connections. Having long axons and dendrites to connect to other cells would be impractical, as agitation of the brain would result in cell damage, even more easily than occurs in terrestrial animals' brains. Without these elongated structures, this limits the number of other cells to which any given cell can connect. With fewer connections, the brain becomes less complex. When agitation of the fluid brain can break connections, the brain becomes unreliable. SO, TL,DR: No, a fluid brain would not be practical, since it could not form a sufficiency of long-term connections to other cells. [Answer] You might want to check out [quorum sensing in bacteria](https://asm.org/articles/2020/june/how-quorum-sensing-works). Bacteria can form a colony that behaves like a single bit more intelligent organism. Nothing would really prevent same thing happening in liquid with a bit more loose organization. It's functioning is not going to be as determinate as that of a brain or even that of a colony if the cells float around, but that was not stated as a requirement anyway. > > Bacterial communication relies on versatile chemical signaling > molecules called autoinducers, which regulate bacterial gene > expression in a process known as quorum sensing. Like languages > between humans, these signals vary between species. Some bacterial > species can interpret many different signals, while others respond to > a select few. Quorum-sensing allows individual bacteria within > colonies to coordinate and carry out colony-wide functions such as: > sporulation, bioluminescence, virulence, conjugation, competence and > biofilm formation. > > > [Answer] [DNA computers](https://en.wikipedia.org/wiki/DNA_computing) The machines we are used to, as well as our brains, rely on parts mounted in stable places with connections between them like axons, wires, or shafts. It is these solid-state connections what gives structure to the machine, what allows one part to move another one and that one move yet another one, instead of just making random noise. However, nature shows us that there is another approach. When the parts of a machine are sufficiently specific, like enzymes and their substrates or complementary DNA strands, you can just let them float freely instead of keeping them near the parts they need to interact with. A floating enzyme molecule can bump into thousands of incompatible things and nothing happens, but once it meets with its target by chance, they click and perform an operation. The result of that operation then floats on and waits to meet the next operand. You may think this must be terribly inefficient, and to some extent you would be right. Systems like this can be fast as long as they are small, like cells; Or they can be slow but smart, like the mentioned DNA computers. Either way, it sounds like a viable strategy. [Answer] The brains of your hypothetical aliens could be fluidic computational systems. Fluidics is a technology that uses fluid instead of electricity. Turns out this can be used to make computers. Trouble is that electricity powered computers are faster and better. By crude analogy, brains might evolve that work on fluidic principles. The main problem is that neurological systems based on cellular structures and nerves running on chemistry and electrochemical impulses are far superior to fluidic equivalents. The other big problem is that fluidic brains will work better at organising the behaviour and cognition of fairly simple creatures like Starfish. It seems unlikely they will work for aliens who can possess civilisations and technology. There is the not inconsiderable problem of how their memories will work. Although an organism could have a distributed system of cells in its body that act like the neurological structures that are the basis of our memories. Now that's plausible. For further research, you may wish to look Stanislaw Lem's novel Solaris (1961) which has planetary wide ocean that is an intelligent being. Well, that's the premise of the novel. The story is mainly the difficulties of communicating with it. Similarly you simply make it a premise of your story that your aliens' nervous system work on the starfish principle of fluid flow (as you described in your question). Unless your story is about research into the neurology of your aliens, don't need to explain in detail how their brains work. [Answer] Just to clarify, starfish have water circulatory systems, but they don't use seawater to run their nervous systems. Starfish have nerves just like you do, and even something sort of like a brain, in the form of a central "nerve ring". This ring is different structurally from the ganglion that most cephalized species that lack a true brain have, but it still works essentially the same way, as a control center for the peripheral nerves. Now, as for the idea of a "liquid brain", this is a cool idea. On the surface, the answer would be no. Brains are dense networks of connected neurons. Even a brain that worked very differently from ours would probably still need to be able to form connections in order to store the patterns that it would need to have things like thoughts and memories, or even to do the basic work of a brain. There are a couple of ways around this though I think. The first is to have it not really be a liquid, but some sort of semi-fluid slime that still has a densely connected microstructure, like snot or biofilm. This sort of substance could still hold enough of a structure for connections to be stable, while being able to deform and fill its space like a liquid. If you want a true liquid, there are really only two ways I think it could work. 1. it's a very still, cold liquid that doesn't get jossled around much. This could work for a sessile species on some freezing planet, but a good smack would probably be enough to give them brain damage, so there would have to be some explanation for how such a fragile brain can exist at all in this environment. Something like a superfluid brain existing in a species that lives in the cold vaccuum of space or something would be cool and might be able to form the connections necessary to work in a liquid medium. 2. Quantum magic handwavy goodness. Birds can see magnetic field lines via the action of entangled cryptochrome molecules that are connected to other molecules nowhere near them. Plants make use of quantum computing algorithms to ensure that photons always take the most efficient path through the thylakoid. We have no idea how these quantum effects are kept stable in the wet, warm chaos that is a biological system, but they are. I have no idea how such a thing could possibly work, but you could essentially do the same thing as the superfluid brain (connections are formed by quantum entanglement and other assorted handwaving) but in a regular environment, just going "yadda yadda quantum biology yadda yadda" and not worrying too much about the details. There are real quantum systems that maintain their stability in biological environments. We really have no idea how they do it. And so there is a real possibility that a biological liquid quantum computer could exist in story space, even if it's extremely unlikely that one ever really would. [Answer] Yes but it would have to be huge due to having to use water flow rather than electrical impulses. So computers are binary, on/off, you could do the same thing with hydraulics, valves and pumps etc.. and we do for a lot of machinery on a very simple level. But for any sort of reasonable complexity it would have to be enormous. [Answer] If they do live in water, then you could say that they have a small liquid brain that acts as an interface between them and the water, and that the water acts like a "shared" brain between them and nature. In that sense they are like a big co-operating organism with huge computational and experiencial power. [Answer] An interesting analogy to a "liquid brain" is the adaptive immune system. Our body's B-cells and T-cells really do compute in that they memorize self (to know not to attack it) and memorize pathogens. The immune system is developmentally distant from our neural system (mesoderm derived vs ectoderm), but achieves some similar computational goals. ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/235724/edit). Closed 1 year ago. [Improve this question](/posts/235724/edit) I need a change in history so in the year 2020, Ireland is ruled by a Constitutional Monarchy. It is still a catholic nation (not celtic), has a democratically elected parliament and leaders, and the monarchy is respected by the Irish citizens... at least most of them. Every other nation, along with their political relationships, should be as close to the present as possible. This also applies to the Irish Republican Army. It still exists as an armed organization. However, I want this organization to only use political means (not bombing or gun violence) to achieve the aim to turning Ireland into a republic. There would be some connection (unofficial channel of sorts) between the monarchy and the IRA. And the portion that is in North Ireland will have the same fate as its real life counterpart: fight, lose, and then truce alongside demilitarisation. [Answer] ## The british army reformed early, and won WW1 faster. When Britain had a war with Tibet in 1904, they incorrectly believed Russia was supplying Tibet with arms. In this alternate universe, Russia was supplying Tibet with arms. It was a brutal slog, which only succeeded when Britain learned to use indirect artillery fire and heavy machine gun fire. This led to army reforms. In WW1, a more effective British army defeated the Germans in 1917, before the USA got involved. ## The Irish war of independence failed. In 1919 to 1921, Ireland fought and won a war of independence against a war weary Britain worried about American influence and unwilling to be extremely brutal. In this timeline, America stayed independent and the British public was much less war weary. The rebellion was brutally crushed, and most of the war eager rebels murdered. ## King Edward VIII fell in love with an Irish woman. He was a very famously short lived king who fell in love with an American woman irl. In this world, he fell in love with an Irish woman. With the money of Britain increasingly depleted in the great depression, Britain decided on a compromise to stop the increasing chaos and expense of Ireland. A partitioned Ireland, with Edward VIII as king alongside his Irish wife. This Irish woman was a member of the IRA. Forever more, the IRA and the monarchy would be entangled in a confusing mess of alliances and relationships. [Answer] The British Monarchy becomes the Irish Monarchy. Ireland has not had its own monarchy for about a thousand years. The quickest way to get an Irish monarchy is to move the British Monarchy to Ireland. Ireland never established its independence from Britain. Due to better treatment than in the real world, following the Act of Union there was no War of Independence. Ireland remained an exclave of the British Empire. They worship the British Monarch. Then one day England gets conquered. Perhaps during WW1 or WW2. The monarchy flees to Ireland. They become the kings and queens of Ireland and nowhere else. Edit: Britain losing WW1 or WW2 is because they were stretched by pouring funds into Ireland to improve the quality of life for the locals, rather than enlisting their sons for a pittance to fight and die in their wars overseas. This is the same reason Ireland is happy to remain in the union. Because the locals see the benefits of staying in the Union. I leave to your imagination what happens after the war. Perhaps Britain becomes a German speaking nation and is otherwise similar but more efficient than real Britain. Perhaps the Allies retake Britain but culturally the monarchy never recovers. They are resented for fleeing and abandoning their people. Perhaps Ireland then becomes independent and keeps its monarchy. [Answer] ## The monarchy came about during the Civil War This is tricky, because you'd need to establish an Irish monarchy after the formation of the IRA. I can't see there being much room between the British and the IRA for an Irish monarchist faction before or during or immediately after the War of Independence. The best loophole is the Civil War, where Ireland is basically independent but the IRA is fractured. Insert a monarchist faction that beats both of the real history factions (de Valera gets assassinated on the same day as Michael Collins, as do his cabinet members), or have de Valera or some near equivalent gain total control and declare themself king, followed by a transition to constitutional monarchy after he dies. With EdV as an absolute monarch, the Catholicism goes to the next level. Sinn Fein outlasts the IRA's military wing just like in real life. Depending on the king's ancestry and politics, you have just made Ulster into Westeros; the Troubles now have royal families leading both sides. Dolores O'Riordan's biggest hit ends up having even more historically inspired emotional turmoil driving it. She still dies young. Edit: The IRA doesn't attack the Irish monarchy with arms in very much the same way Islamist groups don't attack Saudi Arabia. They would like to on paper, but the monarchy/army is ruthless and very good at quelling internal terrorism, while not giving a brass razzoo about what they do to the North. [Answer] Scotland setup / schemer Prince Ireland remains in the UK with a status similar to Scotland and North Ireland in our world. Maybe other parts of the Empire (Canada, Australia) are also still part of the UK. <https://en.wikipedia.org/wiki/Constitutional_monarchy> > > The United Kingdom and the other Commonwealth realms are all > constitutional monarchies in the Westminster system of constitutional > governance. > > > The NRA in your world wants Irish home rule and independence and as you have taken away the historic violent aspects, functions like our world's Scottish [Home Rule](https://en.wikipedia.org/wiki/Home_rule) movement. Other commonwealth members each have their own home rule movement; especially the Isle of Man which thinks it can become Grand Cayman. The popular prince has considerable personal wealth and is a political actor to a greater degree than Prince Charles in our time. He supports the home rule movement in all Commonwealth members, "devolved parliaments" and political independence for Ireland, Scotland and other commonwealth members except the Isle of Man. This support is both public to the degree his public role tolerates and to a greater degree private. If the NRA and prince get their way the role of the monarchy would not change; only the parliamentary aspects of the government would change. [Answer] "This also applies to the Irish Republican Army. It still exists as an armed organization. However, I want this organization to only use political means (not bombing or gun violence)" This I think answers the question. The IRA never promotes armed revolution so never Becomes popular enough to rebel against Britain. Instead monarchist faction that Advocates for armed revolution becomes popular among the people. Then it just takes the place of the Ira in are time line. Meanwhile the original Ira Continues to use activism And political means only After the revolution they use it Against the Irish monarchy instead of the English monarchy. [Answer] No Norman Invasion! It seems hard to believe that the Irish independence movement from starting with 1798 rebellion could bring about an Irish monarchy as they were strongly republican, as were most movements since then. However, if you go back in time to the Norman invasion, Ireland had a number of kings, including a high king. The king of Leinster was ousted from power after he kidnapping the wife of the king of Breifne, so he ran off to look for help from the Normans to get his land back, which is what triggered the Norman invasion of Ireland. Take that away and you've now got a completely different Irish history, but with kings and queens. So there are still a number of things to explain, but history being so different, you can now make up what you like, for example: A strong king came to power from the O'Brien family in Munster and became the high king, and managed to mostly unite Ireland as a single and strong entity, helped by being descended from Brian Boru. They had strong enough personality and were diplomatically skilled enough to somehow or another ensure that England didn't invade anyway in the following centuries. However, the McLoughlins and O'Neills of Ulster never really warmed to this dynasty from the South, and eventually, after the time of Henry VIII started making deals with Protestant English rulers in exchange for help resisting the O'Briens. So the North began filling up with Protestants loyal to Britain as it did in real life, and that is why we still have the strife now. But by the time this happened the people who came over weren't as motivated as Strongbow and Ireland was more united which is why there wasn't a large invasion like the Normans did IRL. ]
[Question] [ I have been wondering how galactic features could impact interstellar civilizations in the process of colonizing a galaxy (either andromeda or the milky way). According to [this video](https://www.youtube.com/watch?v=nGpy4QRtCrU) these features, specifically the arms and the core, could be areas in which life would have a harder time developing due to stellar activity and radiation, but I can't help but wonder if they'd also be obstacles for spacefaring and interstellar civilizations. Additionally, the interstellar civilizations in my universe have access to FTL technology but it requires very precise calculations and conditions in order to be exploited not to mention that generally it can only be used to jump only to nearby systems due to energy constraints. So with these considerations, would these features be relevant obstacles? [Answer] That's a good start for space hazards. Even though humanity has only dipped our toes into space, we are still very concerned about radiation. Not only is there a cancer risk, but there as also a risk to electronics. Things like [single event effects](https://en.wikipedia.org/wiki/Single-event_upset) can eventually render electronics useless. In addition to radiation, [nebulae](https://en.wikipedia.org/wiki/Nebula) are also to be avoided. These ionized gases may react with the spaceship but also increase the temperature to an unacceptable level. More things can be concerning: stellar activity (as you have identified), gravity wells for large stars you cannot get out of, potential effects of things like [stellar wind](https://en.wikipedia.org/wiki/Stellar_wind), and not to mention simply monitoring for new objects coming into view as you speed by. Yes, space is big, but you will feel like a soon-to-be-dead fool if you miss an encounter with a planet that knocks you off course or you manage to hit something. Edit: We should also acknowledge that we just have not gone very far into space, and there may be more things to worry about that we simply don't know or cannot totally answer here. Maybe cosmic rays outside the heliopause become a nuisance. Maybe wandering, primordial black holes are super common. We just don't know! [Answer] Flipping Black-holes. They normally have predictable rotation, an accretion disk that behaves in a nice orderly fashion and an ejection of x-rays and very fast ions in regular and expected directions at the poles. You'd think that staying away from the cones of space that line-up with the axis of rotation would protect you from all that high energy nastiness ejected, but.... Sometimes they [flip magnetic fields](https://www.nasa.gov/feature/goddard/2022/nasa-s-swift-tracks-potential-magnetic-flip-of-monster-black-hole) N-S to S-N, sounds trivial right? Not so. The energy output vastly increases and the direction it's directed in - well, space in any direction can suddenly become very hot and uncomfortable for any ship or planet or star-system caught up in it. These sudden fits of super-brightness in the X-Ray, UV and relativistic ion energy-output in all directions are quite unpredictable and without any apparent obvious warning - if you're within a few tens/hundreds of light-years and one of these things happens - then all bets are off for survival. [Primordial black-holes](https://en.wikipedia.org/wiki/Primordial_black_hole#Observational_limits_and_detection_strategies). These create a special hazard as they may not have any accretion-disk and would thus be invisible - depending on the amount of Hawking radiation they emit - inversely proportional to their size. The Little ones can look like harmless wandering stars that suddenly grow in the magnitude of the radiation they release then essentially explode in a vast cataclysm of energy. The big ones, can be more-or-less invisible until they perturb your solar-system's planets orbits enough to ruin all your plans to visit. Don't smack-into one. [Answer] Gravity and radiation might make them difficult to contend with, but who cares. Because if you're only moving to close stars you won't be getting anywhere near them. So they shouldn't be problems. [Answer] Just yawning stretches of emptiness. Perhaps civilisations like ours in the spiral arms can only really hop along the arms. Travelling large void areas would just take too long. Perhaps all the interesting stuff is just too far away. [Answer] STL travel is limited to shielding concerns. Do the figures about how much heat you have to get rid of per square meter, punching through vacuum at 10% of c, with a typical gas density of 1 atom of H per cubic centimeter. FTL happens in some form of hyperspace. Hyperspace is connected differently. Hyperspace is generally more compact, but is folded weirdly so that points that are close together in hyper map to large disances in normal space. But the folds have culdesacs. The folds have large areas where the normal space mapping is in intergalactic space. In Pournell's universe, transitions between stars happens via Alderson drive. The departure point and the target point have to match both solar gravitational potential energy and solar radiation intensity. This means that not all stars have a point of connection between them. ]
[Question] [ I am working on a setting with a large native population of humans who live in a year-round freezing environment, somewhat akin to the real world Antarctic. These humans should be as biologically similar to other populations as possible, however they will be taller and thinner on average than other humans, around 6'0" to 6'4". It is important that this is a long-term population, not a group of recent migrants. Bergmann and Allen's rules suggest that this population should have adapted to be shorter, stockier, and fattier than the tall and lean populations of warmer, arid environments. What reasons can I give to explain this unusual set of adaptations for their climate? [Answer] Another stronger evolutionary pressure could become more important than the baseline evolutionary pressure to be short, stocky, and fat (with those evolutionary pressures dealt with another way, such as warm clothing). For example, suppose that the region is full of short, stocky, and fat giant killer walruses. [![enter image description here](https://i.stack.imgur.com/ktv9U.png)](https://i.stack.imgur.com/ktv9U.png) Image of Walrus attack per Wikipedia The way that the locals survive them is by squeezing into narrow cracks in the ice where their fat predators can't reach them, or by ice climbing up to high shelves of ice or down into crevasses that long limbs and greater height makes it easier to reach, and being thinner makes it easier to fit into. Generally, when defying gravity, you want to be light (which being thin and not stocky helps), but you to be able to reach handholds when climbing, so you want to have long limbs and height. [![enter image description here](https://i.stack.imgur.com/v0tYj.png)](https://i.stack.imgur.com/v0tYj.png) [Answer] ## Relatively recent climate change This can be explained by e.g. an ice age setting in. The onset was about say, 10,000 years ago, average sea temperature went down 12 degrees Celcius. There has been no time for any biological adaptation, on an evolutionary time scale. Also, take into account you have the advantage of humans: they are creative mammals, able to slow down natural selection by protecting themselves. Humans can also adapt to changing climate in cultural ways, like wearing thicker clothing and building isolated dwellings in settlements. [Answer] Coat. [![enter image description here](https://i.stack.imgur.com/J56vt.jpg)](https://i.stack.imgur.com/J56vt.jpg) Scandinavia is cold and snowy in the winter. In some places the Sun does not come up for months! But the mighty Scandinavians do not care. They are cold resistant and taller than most ethnic groups on the planet. How do they overcome their increases surface area? They wear a coat! Fashioned from the hide and fur of a defeated snowbeast, this cloak of fortitude will keep you warm in even the harshest of storms. Your people are like the Scandinavians. They became large during a time of plenty. Then they either moved into the Snowlands, or the Snowlands came to them. They remained tall but became skinnier from lack of food. They resist the cold using coats. [Answer] Technology. Sufficient technology can overcome evolutionary pressures. If, for instance, they have sufficient technology so that shorter, stockier bodies to retain heat isn't a biological advantage, then there's no evolutionary pressure to adapt to the environment because you adapt the environment to you instead. It doesn't have to be high tech, just sufficient tech that is available to all (or at least the majority) of the population in terms of keeping warm. In terms of the setting, you could postulate that there is, for instance, an common, widely available animal, perhaps one that ends up being domesticated, whose hide is so ridiculously efficient at heat insulation that it beats any real-world equivalents such as caribou hide and can not only be used for clothing but fashioned into blankets that can be used to insulate dwellings. The ancestors of the current people discovered how to use it before they had to deal with extreme cold, thus when the cold came, they had tech available to deal with it. ]
[Question] [ An alien species has built Dyson swarms around stars which have orbiting planets with primitive life on them. The section of the star which is facing the planet with life is left uncovered to let the planet receive enough light but the rest of star is surrounded by a Dyson swarm in the shape of some sort of creature of their choosing. The swarm can be up to 10 times the diameter of the star in any direction and for this question we can base it on our sun and visibility from Earth. How visible would this Dyson swarm "creature" be on the planet at any time of the day (sun rise and set may be better as there is less glare)? [Answer] > > The section of the star which is facing the planet with life is left uncovered to let the planet receive enough light > > > This is slightly more awkward than you might think, on account of the elements of the swarm orbiting the sun at a different rate to the planet (because their orbital radii are so different). On Earth you can create things like [sun-synchronous orbits](https://en.wikipedia.org/wiki/Sun-synchronous_orbit) which [precess] [2](https://en.wikipedia.org/wiki/Precession) with a period of a year, but that relies on the Earth being a slightly squashed shape and the Sun is just too round to be able to pull tricks like that. This means you'll either have to have quite a sparse swarm (eg. wide orbital radius, wide spacing between elements) or the elements will need a way to let light past when they'd otherwise shade the planet. > > the rest of star is surrounded by a Dyson swarm in the shape of some sort of creature of their choosing. > > > This will definitely need the elements to have some kind of ability to change their habit of reflecting/occluding light. As the swarm elements transit the sun, they either need to rotate their collecting surfaces so they're parallel to the light rays directed at the planet, or they need to render them somehow transparent (like [venetian blinds](https://en.wikipedia.org/wiki/Window_blind#Venetian), perhaps) so they let enough sunlight past. Whatever trick they use, the same approach can be used to modulate the silhouette of the swarm (by selectively letting some starlight past, or by deliberately rotating the collectors away from the sun to block starlight directed at the planet) or to deliberately reflect additional sunlight towards the planet. > > How visible would this Dyson swarm "creature" be on the planet at any time of the day > > > Elements that appear to be close to the sun but not actually occluding it will be more or less invisible, most of the time. Special circumstances like solar eclipses by a suitable nearby body that doesn't also wholly occlude the swarm would work very well (and a monster head that appeared during a solar eclipse would certainly be one for the history books) but general observation will have to wait for the invention of the [coronagraph](https://en.wikipedia.org/wiki/Coronagraph), which is not an easy thing to discover. After sunset, or before sunrise, a wide enough swarm can be as visible as its creators want. Light can be directed towards the planet, which is probably the most effective way to announce its presence, and a large enough and dense enough swarm will block out stars in a particular region of the sky. There's a tradeoff to be made between swarm density and keeping the engineering difficulties of keeping the planet illuminated and a fancy shape visible, so let me suggest something rather different. The oft-mentioned [Nicoll-Dyson Laser](https://en.wikipedia.org/wiki/James_Nicoll#Nicoll-Dyson_Laser) is generally brought up as a means to blast people at stupendous distances, but it could also be used to illuminate a planet. Basically you fit an optical phased array laser to the non-collecting side of each swarm element, that lets you emit beams of light of varying powers and directions (and depending on how your array works and your tech level) different frequencies, too. This would let you have a sun of almost arbitrary shape and colour, because what the planet sees isn't a star at all but in fact a stellar-scale lightshow. Just the shape of a an animal? Pah, think bigger! Imagine the sun appearing as an actual animated face! Think of the fun you could have. Any by way of a bonus you can smite your enemies even if they're a million lightyears away. What's not to like? [Answer] ## Leave a gap, the sun could look like a (tilted) rectangle The Dyson swarm will be a 2 part construct, north and south The swarm resides inside Earth's orbit: 10x diameter of the sun, which is about 1/10 AE. Suppose this swarm is dense. It will be built to catch a lot of sunlight, so it does. The Earth is in orbit and you want it to receive sunlight. So you'd have to [leave a gap](https://www.reddit.com/r/Dyson_Sphere_Program/comments/ldixqd/the_first_diagram_of_a_dyson_sphere_i_saw_as_a/) in the swarm, Sun can lighten up Earth in its equatorial surface. [![enter image description here](https://i.stack.imgur.com/0k9N7.png)](https://i.stack.imgur.com/0k9N7.png) A rectangular sun The opening could be narrow. Some spreadsheet-mentality alien could have calculated how much sunshine planet Earth really needs. In that case, the opening in the Dyson swarm could be so narrow it affects the shape of the Sun. Note about more than 1 planet If you want to support more than 1 planet they must all orbit in the same plane. The opening in the Dyson swarm is designed to shed light on Earth's orbit plane only. Any other planet outside that plane will receive sunlight only 2x per year. The usual night sky, spectacular sunset and sundawn No difference at night. When your dyson construct of 1/10 AU diameter is below the horizon, the sky will look as usual. There is no difference in the night sky. Sunset and sundawn could be spectacular.. there would be a ring around the sun, you'd see the opening in the Dyson swarm. [Answer] I would expect almost the entire creature to be invisible, except perhaps the inner surface of the opening (presumably circular) that faces the planet. The sun is really the only significant source of light in the system. Other planets are only visible because of the sunlight they reflect. There would be no light shining on the creature's exterior. Other stars are far too distant to illuminate it at all. The sun will appear to sit in the center of a giant starless void. Unless the opening is much larger than necessary, the bright light from the sun will drown out the brightly lit interior back surface of the creature. The back may be so bright that the sun looks larger. ]
[Question] [ I have read about [hybrid speciation](https://en.wikipedia.org/wiki/Hybrid_speciation#:%7E:text=Hybrid%20speciation%20is%20a%20form,isolated%20from%20the%20parent%20species.): "speciation where hybridization between two different species leads to a new species, reproductively isolated from the parent species". I wanted to know if it would be possible for two members of the homo genus to come together, create a hybrid species, and having that species/subspecies reproduce isolated from the parent species, given these parameters for a potential story: * A Homo sapiens and other member of the Homo genus (like a Neanderthal) come together to produce and child. Other members of both human species follow suit. * The union leads to hybrids that can be considered a new species/subspecies of the Homo genus. These hybrids separate and reproduce * The hybrids continue to live on a produce more of their new species. This species continues to exists as Neanderthals die out and competes directly with homo sapiens, forming their own society that continues into this alternate-worlds version of the modern day [Answer] *It's more accurate to say that it happened.* The human species, at least, most of the human species contain trivial amounts of DNA believed to have come from [Neanderthals](https://en.wikipedia.org/wiki/Interbreeding_between_archaic_and_modern_humans#Neanderthals). This means that at some point there were individuals who were the result of a mixed set of parents and successfully bred back into the Homo sapiens gene pool. Thus, hypothetically anyway, it's possible for a tribe to form out of purely mixed individuals and if they managed to eschew contact from any other humans for all this time, they might very be considered a separate species of the Homo genus. [Answer] Interbreeding: The interbreeding part is no issue, as it happenned in our own history anyway. From some research, it seems possible that modern humans last interbred with Denisovans as recently as 15 000 years ago. From DNA evidence, after moving out from sub-Saharan Africa, Homo sapiens interbred with Homo neanderthalensis in (most likely) Europe or possibly the near/middle east as well as with Homo denisova in Asia. Colonising Europeans later interbred somewhat with Africans leading to small amounts of Neanderthal DNA in African populations as well. Hybrid "Species" This would only really happen if the hybrids were isolated from other population groups and evolved seperately from that point on, e.g. a small mixed group of H. sapiens and H. neanderthalensis or a few hybrids tossed out of their birth tribes for being "freaks" crossed a land bridge (or series of them) that later sank, or crossed into a valley that somehow got isolated from the surroundings. After that point, they have no further contact with other populations for say 20k years, developing seperately. Eventually, they come in contact with modern humans and ... So, could be done, with a few lucky/unlucky coincidences. Actually, I suppose you could argue that Europeans/Asians are actually such a hybrid species, even though with a higher percentage H. sapiens versus H. neanderthalensis in their make-up, while Africans represent "pure" H. sapiens References 1. Lu Chen, et.al. Identifying and Interpreting Apparent Neanderthal Ancestry in African Individuals, Cell, January 30, 2020, DOI: <https://doi.org/10.1016/j.cell.2020.01.012> 2. Leslie Nemo, Discover Magazine: <https://www.discovermagazine.com/planet-earth/everyone-has-neanderthal-dna-in-their-genome-new-genetic-analysis-shows> ]
[Question] [ Sexual dimorphism, that is the difference is size between the male and a female of the same specie, is common yet normally not extreme. There are however species where the difference is extreme: I remember reading about a fish where the female is about 1 meter long, while the male is a couple centimeter long, essentially a testicle living inside the female body with the sole purpose of fecundating her eggs. In my world I want for such extreme dimorphism to be the norm among multicellular organisms using sexual reproduction, at least in one biome. Which biome would favor extreme (female size/weight: male size/weight >= 50:1) dimorphism to be the norm in the vast majority of the species occupying it? [Answer] IMO, You're stuck with water. 50:1... That means (for example) a 2 meter human and her 4 cm (yeah... centimeter) husband. For us imperial measure users, that's 1.6 inches. Gravity is not your friend. Any condition where something can be stepped on or landed on (in the case of birds being fertilized by gnats) would cause serious problems that, frankly, no amount of intelligence could easily fix. It's morbid... but I can imagine the males of a land-based species being eaten by dogs and stepped on by female children at play.1 [Obligatory Futurama video](https://www.youtube.com/watch?v=45-jBIGuxww&feature=youtu.be&t=328). Off the top of my head, the only biome that permits freedom of movement without substantial consequences due to gravity are water-based. I think you're stuck with it. You'd still have a problem with the males being easy food for females of different species... but at least it could happen. --- 1 We need to honest here... distraction would kill lots of males. Females walking down the street or simply bears wandering through the forest (whether your looking for an intelligent species or not). Just rolling over in your sleep would be disastrous. Gravity is not your friend. [Answer] You are probably thinking about anglerfish; they inhabit a biome which is very poor in nutrients, the abyssal zone of the oceans. I believe this adaptation minimizes the nutrition needs of the male, so that a family of bonded fish is more food-efficient than otherwise. By the way, those guys do bond - the male bites the female and fuses to her permanently, connecting her circulation to his. Also in the abyssal zone there is the [boneworm](https://en.m.wikipedia.org/wiki/Osedax), ehich might be the animal you had in mind: > > Between 50 and 100 microscopic dwarf males live inside the tube surrounding a single female and never develop past the larval stage. > > > These critters thrive by feasting on whale bones which are sparse and scarse. They need to be efficient. Again I think that males skip developing past a larval state in order to conserve energy. --- Other biomes where food is scarce, such as deserts, don't have such extreme dimorphism. I believe it's because deserts change relatively quickly in geological time, lasting for millenia to dozens of millions of years. But the abyss has been the abyss before life even started, so it has had more time for fauna and flora (bacteria) to evolve extreme features. [Answer] Apparently its not exactly about habitat. This kind of sexual dimorphism in which the female is several times larger is usually rare, being more observed in some spiders and in 5 out of the 11 anglerfish species we know. In the latter, the males are essentially sexual parasites, using its eyes and/or nostrils to find the huge females. After that, they latch onto them, usually in the underbelly, and basically [fuse with the female](https://www.livescience.com/49330-animal-sex-anglerfish.html#:~:text=Unlike%20other%20anglerfish%2C%20ceratioid%20anglerfish,are%20much%20larger%20than%20males.&text=Once%20a%20male%20finds%20a,region%2C%20while%20he's%20upside%20down.), connecting tissues and bloodvessels and becoming completely dependent on them to survive. In spiders as [this article](https://www.annualreviews.org/doi/full/10.1146/annurev-ento-011019-025032) speaks (unless I understood something wrong), the difference in size seems to be mostly due to opposing selecting pressures to each sex, but this can't exactly be considered the only reason, with other factors like sexual selection and gravity hypothesis (smaller males can climb better and reach the females more easily) also being applied. Other factors like why in some species there's virtually no difference and in others the males are clearly smaller aren't quite clear yet. Overall, it'd seem like it's not a matter of biome, as these 2 cases clearly have little to no similarities other than the extreme size. This seems more related to behavioral patterns, sexual selection and, possibly, different lifestyles (see harpy eagles, although their size difference isn't nearly as pronounced, it exists, and allows for a difference in prey, with the smaller and faster male hunting smaller, yet more agile prey, while the heavier and stronger female hunts larger prey, with both facing very little competition from one another normally). But it'd seem like a development in which mature males act as sexual parasites towards the females, as we see with the angler fish, or in which both adapt for extreme differences in type food they eat should be a strong motivator (a comparative yet very unlikely herbivore example could be one in which smaller males exclusively eat grass while much larger females feed on the leaves of trees, although we'd need to watch for the necessary adaptations that'd allow for reproduction despite such a difference in size and weight). The main issue here for your ecosystem to work is the 50:1 ratio. For this to allow you're essentially stuck in scenarios in which the male is much smaller than the female, and it's her which will limit the max size. It's unlikely we'll have a scenario in which the male is, for example, the size of a bull. And that is not mentioning how not even spiders usually have such drastic levels, so we'd essentially need an ecosystem in which basically all males attach to females after reaching sexual maturity and convert into a spermsack for sexual reproduction to work, or have other similar methods to transfer sperm. ]
[Question] [ *WARNING: This post contains some spoilers for the anime/manga Dr.Stone.* As I'm watching Dr.Stone, I see Senku and the gang trying to make vacuum tubes for their circuits. The vacuum tube is an ancestor to the transistor. It is quite hard to make and is fragile because glass is used to enclose a vacuum and the metal (Tungsten) inside has to get quite hot. Transistors, however, can be tiny and easy to use. I know enough Physics and Electrical Engineering to know pretty well how transistors work but I'm not sure how they can be made. The environment and circumstances in the world of Dr. Stone: * There's a single (genius) scientist from the modern world (everyone in the world got turned into stone and some got unpetrified after some thousands of years) * They can do metal work and smithing * They have a water wheel that can generate some electricity * They also have some batteries * They're making wires out of gold * A furnace is available but runs on either manual pumping or on the water wheel * Many common metals are available Can they make transistors in such a world? If yes, about how small can the transistors be? [Answer] No, they can't. To make a transistor you need to be able to smelt and refine to high levels of purity specific materials like Silicon, Germanium, Boron, Phosphorus and the like, and for some of them you even need a specific crystallographic set up. While Silicon and Phosphorus are easily found in their bound state, refining them is beyond the capabilities of stone age, even your stone age + furnaces. Let alone controlling the crystallographic orientation of Silicon. The [Czochralski process](https://en.wikipedia.org/wiki/Czochralski_process) is simply too complex for stone age, > > High-purity, semiconductor-grade silicon (only a few parts per million of impurities) is melted in a crucible at 1,425 °C (2,597 °F; 1,698 K), usually made of quartz. Dopant impurity atoms such as boron or phosphorus can be added to the molten silicon in precise amounts to dope the silicon, thus changing it into p-type or n-type silicon, with different electronic properties. A precisely oriented rod-mounted seed crystal is dipped into the molten silicon. The seed crystal's rod is slowly pulled upwards and rotated simultaneously. By precisely controlling the temperature gradients, rate of pulling and speed of rotation, it is possible to extract a large, single-crystal, cylindrical ingot from the melt. Occurrence of unwanted instabilities in the melt can be avoided by investigating and visualizing the temperature and velocity fields during the crystal growth process. This process is normally performed in an inert atmosphere, such as argon, in an inert chamber, such as quartz. > > > like also [zone refining](https://en.wikipedia.org/wiki/Zone_melting) > > Zone melting (or zone refining or floating zone process or travelling melting zone) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is melted, and this molten zone is moved along the crystal. The molten region melts impure solid at its forward edge and leaves a wake of purer material solidified behind it as it moves through the ingot. The impurities concentrate in the melt, and are moved to one end of the ingot. > > > ]
[Question] [ In my story, there is a planet that experiences near constant sunlight. Since sunlight so plentiful and reliable most organisms are, at least in part, photosynthetic. The only intelligent life on this planet is plant-like people that get their energy entirely from photosynthesis, and absorb nutrients and water from suitable soil (which is not rare). They are roughly similar to humans in size, shape and appendages, and general intelligence. They are mobile, because they are prey, although this changes as they get older: they never stop growing and can live for several centuries. At some point, the creature becomes so large that it plants itself and never moves again. These elders continue to grow wiser as they age (their bodies essentially becoming shelters for continually growing brains), though not many reach these extremely old ages. They have never really developed a psychology that promotes warfare for three reasons: 1. Since they are photosynthetic, they don't need to kill (or even farm) for food. 2. They are hardy, and younger members can quite reliably regrow, which makes war among the species impractical with their level of technology. This is so reliable that 'murder' in their society is still a crime, but not nearly as terrible as it is on Earth 3. Their predators are much more capable than them, so they can't feasibly exterminate them. My question is fairly open ended: these creatures don't need to collect resources for food or shelter, so what would drive them to do anything but lay in the sun all day? The species prizes the arts over sciences, but I can't see why or how they would have developed the tools to make paints, instruments, sculptures, etc. [Answer] The best way to figure out what motivates your creature is to consider the constraints it lives under. Energy Requirement First, let's see if your creature can get the energy it needs. An average person consumes about 2000 calories per day (food calories, or 2000 kcal). That's equivalent to 2.3 kilowatt hours of power. Energy in sunlight at the equator is about 2300 Watts per square meter. A human has about 1.7 square meters of surface area, but only half would be facing the sun at best. Let's say it's a big creature, and therefore has 1 square meter of surface area facing the light. The most efficient plant at converting solar energy is sugarcane, and it converts 3.5% of light into energy. So the available energy to the organism will be 2300 Watts \* 3.5%, or about 85 watts. So to get the amount of energy that a human consumes in a day would require your creature to absorb 27 hours of direct sunlight, assuming the sun was as bright as the Earth's at the equator. But that's a very, very optimistic number. Every detail from there makes it worse. For example, maximum solar efficiency requires that the collector be tilted to the angle of the sun. Then there's cloud cover, and shade, and... On Earth, a large tree on average collects maybe 200 calories of energy in a day. That gives you an idea of the real world efficiency of photosynthesis. Planet Problems My understanding is that a tidally-locked planet close enough to a star would have any water evaporate from the day side and freeze out on the night side. If the planet is far enough away for liquid water to exist on the day side, it's not going to get nearly as much solar energy. On such planets, the only areas where a plant species might survive would be along the terminator, but the solar energy on the terminator would be much lower. Also, there would be a lot of clouds in that area. On a cooler tidally locked planet you could have water on the 'day' side, but probably only if there was enough water for a global ocean, because the water on the 'day' side would be melted ponding on top of the ice. If there wasn't enough water to go around the globe, it would still all be transported to the 'dark' side where it would freeze out into a permanent ice cap. Perhaps on such a planet there would be a larger habitable zone along the region where ice turns to water. Again, you would expect lower solar energy there than at the hottest place on the planet. There might be a way around this - we don't know much about such planets, and there are probably variations we haven't thought of. But it will take some work in planet design to come up with an eyeball planet that can host sentient plant-creatures. Creature Design But I think that's still do-able. Your people would have to be large, spread out, maybe with leafy sprouts all over to maximize surface area. They'd probably also be slow moving and slow thinking, as thinking takes lots of energy. Consider creatures like a Tree Sloth. A Tree Sloth only uses about 110 calories per day. So a large, slow-moving creature with lots of surface area could possibly work. What would motivate such a creature? Lots of things. For example, first contact with a faster thinking, faster moving species like us. Or a natural disaster, such a plague of mites or bugs that starts eating them, requiring them to up their game. Or another natural problem such as drought or CO2 depletion. If you are asking what motivates them as a species absent any external shocks, that's a bit tougher. Why would such a species evolve intelligence in the first place? What problem does that solve? Perhaps they have a symbiotic relationship with another species that can tolerate heat better. Maybe there's a type of vine that grows underground for long distances, then sprouts where it's hot and very bright. The symbiosis is that the sentient species provides water to the vines, and the vines return nutrients for the people or something. Here's a potential idea: They are networked. Rather than move around and consume energy, they are motivated to connect to each other either through roots or temporary physical contact. Because if they can share their chemical resources and concentrate them , they can advance and prosper. Perhaps they all started out equal and non-sentient, but once they started connecting together some evolved the ability to extract extra nutrients from the network, and they became smarter and faster thinking. Eventually they all became sentient, but the creatures in the 'super clusters' in the network get more than their share of energy and therefore evolved more intelligence to manage and improve the network. That creates a society where the powerless have more than their share of energy extracted for use by the 'advanced' ones. So you have armies of plant people who move slowly and without much thought, providing their photosynthetic energy to the 'haves' who need it to think at higher levels. This creates a stratified society where only a few plant-people can really think and work at a high level, but only because the majority have to do with less than they would on their own. But it's stable because the powerful ones do more good for the society through invention or organization that the individuals could do on their own. An analogy would be an anthill with lots of workers, except the 'work' involves optimally spreading out to collect as much light as possible. This feeds energy back to the 'hive', or cluster of higher-level members of society (although in an anthill that's not true - queen ants aren't any smarter than any other ants - they just use the excess energy to breed more). Still, the same idea - masses of creatures that aren't motivated to do much more than find good places to spread out and relax, and their thinking is constrained by lack of energy. In the meantime, creatures in the 'hubs' have plenty of nutrients, so over time they became smarter, faster, etc. Then one of the smart ones invents a new energy source the masses can use to bring themselves up to the same level. As this tech spreads and members of society can supplant their own photosynthesis with extra energy, they start to think better and faster, and decide they no longer need the 'smart' ones. And the 'smart' ones are going to do everything they can to hold on to their power over their society. Wars break out, etc. [Answer] Part one, your actual question: > > My question is fairly open ended: these creatures don't need to collect resources for food or shelter, so what would drive them to do anything but lay in the sun all day? > > > The species prizes the arts over sciences, but I can't see why or how they would have developed the tools to make paints, instruments, sculptures, etc. > > > A few things spring to mind. Firstly, seasonal changes might require migration (even eyeball worlds can have eccentric orbits that could drive a summer/winter cycle) and constructing shelters, clothing or foodstocks to reduce or avoid the need for migration requires some engineering and possibly some form of hunting/gathering or even farming. Secondly, expansion into less amenable landscapes might require some work as well... irrigation networks, clearing unwanted vegetation that might compete for light or secrete inhibitory chemicals, etc. Not quite warfare, but slash-and-burn is a bit more aggressive and closer to home if you're a plant-person. Thirdly, predation. Recognising the presence of, or seasonal arrival of predators and then taking steps to avoid them, evade them or build defenses against them would be an imporant part of their lives All these things go together to form the foundation of a technological society that has to at least occasionally do stuff, and when it doesn't have to do stuff then maybe energy (or food) is sufficiently abundant that leisure time activities could be enjoyed instead of simply vegetating. Which brings me to idea number four: reproduction. Maybe the art wasn't originally for its own sake, or for entertainment, or to impress other plant-peeps. Maybe it was part of a display to make the artist seem more appealing to other species who might be opportunistic or maybe even symbiotic. Pollinators, fruit-eaters, pest-eaters and seed-spreaders, oh my. Maybe even sources of nutrients, either directly (by being eaten) or indirectly (by providing nutrients from their excrement, or maybe even corpses). Self decoration and modification to attract more birds and insects and so on, with a knock-on effect that it would also attract "mates" in the form of other members of the plant-peep species who'd like to bask in the "halo effect" of the ecosystem around a particularly talented individual, and so increase their own chances of reproducing with them. (you could just rub flowers together and avoid pollinators, of course, if you were some kind of deviant, but eew) --- Part two, nitpicks: > > They are mobile, because they are prey > > > This is a somewhat important detail. If they need to be very mobile, they'll probably need a source of energy a bit more concentrated than sunlight (or alternatively, vastly more efficient photosynthesis than you'll find on earth). A sloth isn't going to outrun a pack of wolves, for example (or some other suitably arboreal predator; probably some kind of ape or monkey). > > Since they are photosynthetic, they don't need to kill (or even farm) for food. > > > Are they exclusively photosynthetic? Or can they eat and digest stuff as well? Because being able to supplement your diet is quite a useful thing. Also note that plants are made of more than just carbon, hydrogen and oxygen, and as such need a good supply of many more materials than just air and water (nitrogen, phosphorous and potassium just to start with, and they need to be in a suitably bioavailable form, too). A plant doesn't need to be a predator like a venus flytrap or pitcher plant to benefit from the nutrients tied up in the body of other animals... just murder them somehow (coconut on the head?), smash the body up a bit, bury it in a shallow grave and fill yer roots. > > This is so reliable that 'murder' in their society is still a crime, but not nearly as terrible as it is on Earth > > > Y'know, if you had to work really hard to murder someone, really smashing them up and dismembering them and burning the bits in order to make it stick, wouldn't that be a worse crime? You don't woodchip someone by accident, or in the heat of passion... > > Their predators are much more capable than them, so they can't feasibly exterminate them. > > > Intelligence is an extremely powerful lever. Predators may be more effectively evaded, but they may also be poisoned and trapped and their eggs or young (or saplings, as it may be) found and destroyed whilst the parents are unavailable. The most useful thing an intelligent species can do to prolong its existence and propagate itself is to remove overt threats. Unless those predators are themselves just as intelligent, if not more so. In which case it is in their advantage to farm the dumber and tastier species rather than just letting them run around the place willy-nilly. The situation as you describe it does not sound entirely stable. [Answer] Their peculiar energy economy might cause some interesting behavior. As noted in other answers, the energy density of photosynthesis is going to be a challenge when it comes to cognition. Perhaps it is the case that your creatures are very dependent on the Elders. The Elders are probably going to be subject the square/cubed effects (surface area doesn't scale as quickly as volume, so big creatures are relatively heavy). Despite this, they still get much more energy than their smaller comrades. There's no reason cognition needs to scale with anything in particular other than energy, aka surface area (well there's the need to satisfy motor control which is less significant in your sedentary Elders -- sidenote, movement for an Elder could be a task that requires them to activate their abstract thinking brainparts, which would make it so they couldn't "walk and talk at the same time" so to speak). If we look at Machine Learning (despite the fact that ML/true intelligence analogies are a bit fraught), there's a split between "training" and "inference." Training when the computer looks at the data set and tries to build a model, while inference is when it applies the model (so training might be looking at all the cats and picking out the common features, while inference would be identifying cats). Training is generally more computationally intensive, slow, and massively parallel. So, it might be the case that the Elders receive information from the Sprouts, and use that to build models. Because these are true intelligences and not ML algorithms, these models are more like ways of thinking. The Sprouts go out into the world and try to gather more information/experiences to improve the Elder's datasets. The degree to which this upload/download process is physical or, whatever, psionic, is up to you. But it could be the driver for a significant amount of art building. Perhaps it is really concrete -- the Sprouts re-enact the stories of their adventures to the Elders in little plays or spoken word poetry. Perhaps it is more symbolic -- they draw beautiful patterns that represent a compressed form of knowledge (perhaps these patterns are also Elder specific, so communicating to far-off Elders needs to be more concrete). So, the Sprouts are mostly executing the worldview of the Elders. This makes them extremely dependent on the Elders. They might spend a significant amount of effort tending to the Elders -- cleaning them of parasites, gathering resources, etc. This might also induce some strange behavior on their part. For example, assuming their Elder isn't under some immediate nutrient crisis, the value of a Sprout is mostly tied to the information they carry (because information lasts forever). So a sprout at the beginning of an adventure, who's just info-dumped to the Elder, is relatively valueless and might exhibit extreme risk taking behavior (in an attempt to get more information to bring home), while one nearing the end of a journey just wants to get back. One other thought about the energy situation is that, because the Elders gather much more energy, they might save some (in the form of sap) for lean times. They might also be able to give this out to Sprouts as necessary, to lessen the tyranny of their poor energy economy. All in all, it seems like you've got a pretty good setup for various "worship the great old tree of wisdom" tropes. [Answer] One driver for conflict could be disease. Plant beings that would be dormant for large amount of time during their lives (as people are suggesting from the amount of energy one can collect through photosynthesis), they would be quite easy hosts for parasites. Assuming they have no technological means for getting rid of these parasites (antibiotics, pesticides, etc), quarantine would be the most efficient way to keep infestation to a minimum. You said that they are more artistic than scientific, so locking up a large number of these individuals probably woudln't sit too well with them. EDIT: You might want to check out, if you haven't already, [this species of sea slug](https://en.wikipedia.org/wiki/Elysia_chlorotica), if you want a slightly different take on the photosynthetic sentient beings. This animals eats leaves (or algae, can't recall) to absorb their chloroplasts and use them to generate energy through photosynthesis. Interestingly, coevolution of this slug with its source of chloroplasts means that it has integrated some genes that code for proteins that help sustain the chloroplasts it absorbs that the plant usually produces to maintain them. Very interesting biological phenomenon! [Answer] Well, when you think about it a plant needs more than just sunlight and water, and a plant is also at risk of other factors around them. If you're making the species part plant, then I'd recommend adding What they need: Water: a plant always need the right amount of water, and I noticed how you wrote down rivers so you have that covered. Oxygen: plants need to be exposed to clean air, and since they can produce it as well it would be a type of natural exchange. Nutrients: I know you said nutrients, but it's a bit more than just dirt. Some plants like trees or grass can absorb nutrients from a deceased animal [insert Lion King joke]. But to answer for what could motivate them to move around? well...lots of reasons. Predators: I like how you brought up how predators , but doesn't it explain why they should worry about finding shelter? You also mentioned how they plant themselves when they get bigger, so what says a large animal or an insect could harm them as they stay still in the ground? Pollution: I know you said that they're the only intelligent beings on the planet, but what about natural pollution, like animal waste in the rivers or volcanic smoke rising to the air? They could possibly absorb non-clean nutrients and could possibly get sick or die, right? Over-energize: What are the chances that too much water, nutrients or sunlight could harm them? Every living thing has limits on what they need, and too much sunlight is an actual thing for plants for it could affect their photosynthesis and cause them to wilt. I won't provide changes to your story, for your ideas are your own, but I hope that what I provided helps you out in some way. [Answer] Trees and all other photosynthetic plants are in a constant state of warfare with one another. A walk in a forest might seem peaceful to us humans, but all the plants are throwing elbows, racing to get as much sunlight as possible. It's just that their timescales are so much longer than ours that they seem to be at peace. Trees live and die by slight advantages that allow them to grow faster, crowding the canopy or otherwise sidestepping the straight-line race to the top. Some have evolved to get ahead with some pretty nasty tactics, too. Look at strangler figs, which literally strangle other trees. Or black walnuts, which poison the soil around their roots so that no other tree species can grow nearby. I like the idea of a peaceful plant people, but I wouldn't rush to the conclusion that your plant people would necessarily be pacifists. Maybe there's some middle ground. (I'm reminded of the hermaphroditic aliens in The Left Hand of Darkness who aren't brash men and thus don't engage in outright war, but who do assassinate each other in small numbers when the need arises). Here's something else to consider: photosynthetic plants do not simply absorb nutrients from the soil, and thus are not self-sufficient in that regard. Their roots are intertwined with the hyphae (hair-like threads) of fungi, which provide minerals and other nutrients in exchange for the sugars made by the plant. So as Dan Hanson wisely suggested, it might make sense for these photosynthesizing plant people to develop some sort of symbiotic relationship with another organism (i.e. MUSHROOM PEOPLE!) And unless the plant people's version of photosynthesis were a lot more efficient than terrestrial plants', or unless they supplemented their sun snacks with some other energy source, their metabolisms would be much slower than ours, and so they would likely move around very slowly, like Tolkien's Ents (though I'm guessing you would want to avoid that parallel). I'm wondering: How plant-like are they? And given the staggering variety of Earth's plants, how would you define plant-like? Is their skin bark? Do they photosynthesize through their skin or through leaflike growths? If they are that plant-like, do they also produce flowers or fruits? If so, that could create an opportunity for some sort of artistic expression. On earth, flowers evolved to attract pollinators, but maybe on your world, they're a means of self-expression. [Answer] I think you have a problem with the evolution necessary to develop a species that is intelligent, on the same level as humans, but gets its energy via photosynthesis. Scientists think that one of the crucial developments that allowed us to become more intelligent than the other species on our planet was the development of tools, and the development of tools happened because in our environment, that was the most effective way to procure food. To unpack that a little: when your species is a primate living in the branches of trees in jungles, it's in an environment that heavily rewards making tools. First someone gets the idea to throw rocks at things to kill them. Then someone gets the idea to put a rock on a stick and throw a spear. Then someone gets the idea to make a trap. Then someone gets the idea to store food during bad times in pottery. Each technological invention takes more intelligence than the previous one. In order for the train of development to start, the species had to be in an environment where food can be gotten better by coming up with a very simple tool that that species can use. If a species gets its energy from sunlight and nutrients from the ground, then there's no reason to develop opposable thumbs, or any locomotion at all for that matter. And without locomotion, there's no possibility of developing tools. I think you're right on the money for being concerned. I don't think this species can develop, at least not as we understand evolution today. Perhaps you go a different route with intelligent design or some alien crafted this species or something, but with conventional evolution, I don't see a way it could happen. ]
[Question] [ So I just got back from watching an episode of the Science Channel program Unearthed, a show focusing on archaeological discoveries. In the episode in question, the subject was on the Lighthouse of Alexandria, and one of the questions asked in the episode is how the lighthouse stood true in an earthquake hotspot for 1500 years. One theory was that the granite bricks were connected by a kind of mortar made from molten lead. A demonstration had been tested, and it turns out that a wall of granite bricks and molten lead mortar can withstand seismic shock without problem. Now, obviously, lead is not a metal worth recommending, considering its toxic nature, but are there other metals or alloys that, when still molten, can be used to make mortar? And would it be practical to use them given today's technology? [Answer] Bi58, with a little help. An alloy of bismuth and tin in the proportion 58:42 known as [Bi58](https://en.wikipedia.org/wiki/Fusible_alloy#Other_alloys). by itself has a melting point of 138 °C (280.4 °F), but doesn't by itself have suitable properties to act as mortar, as it needs to be able to stay where it's troweled to and although denser needs the approximate properties of a well-whipped egg-white. The builder's mate would need to either use a spot-board and shovel or a powered rotating mixer and add-in a goodly proportion of copper powder and a little [flux](https://en.wikipedia.org/wiki/Rosin) (to aid wetting), this will give the desired properties. A rotating mixer might just be easier to maintain at the right temperature and small batches would be be ferried to the (brick) layer as needed. On cooling, the mixture expands by a small percentage (1 or 2%) which gives a good grip on the surfaces of rough materials. It has the virtue of being fine with the day/night cooling cycle, so will stay intact over time. [Answer] Using metal as binder between non metallic part is a knowledge we humans are using for quite some time. We still use it today in [Kintsugi](https://en.wikipedia.org/wiki/Kintsugi). In the case of Kintsugi, however, gold particles are added to the binder, instead of melting the gold itself. What would be the requirements for such a metal to be used as binder? * non brittle, to yield when (dynamic) loads are applied and possibly damp them * low melting point, to prevent that the high temperatures alter the other substance * resistant to oxidation, to prevent that in few years the binder is turned to dust The above leave not many alternatives to lead, I am afraid. [Answer] # Metal matrix composites are used in a wide variety of high-end technical applications. A composite material is a material made of two significantly different components that are combined together into one material without chemical mixing, and which typically consist of fibers of a reinforcement material "glued together" with a matrix material that fills up the spaces between them. An example of it is fiberglass, which uses glass fibers as the reinforcement material, and a polymer resin as the matrix material. [Metal matrix composites](https://en.wikipedia.org/wiki/Metal_matrix_composite) are composites that use metal as their matrix material; they can be manufactured using a variety of methods, but simply pouring molten metal over a fiber mesh is a simple (if relatively imprecise) way of producing one. Examples of it include tungsten carbide cutting tools that use cobalt or bronze as their matrix, aluminum-matrix boron carbide materials used for certain high-end automotive applications, and the monofilament silicon carbide fibers in a titanium matrix used in F-16 landing gear. [Answer] The Inca were reported to have used molten lead silver gold and a bitumen pitch concoction that is very thin and boils but hardens well after being poured into tight cracks. With today's alloys I am sure you could do better. However with silver being as cheap as it is, might be the way to go. ]
[Question] [ In my Conworld, the inhabitants have discovered a type of star they cannot identify. I would like it to be a star made not from just hydrogen and helium, like our sun and countless others. But my question here is: Can a star be made of other materials? I am mainly interested in: * Oxygen * Nitrogen * Neon * Argon * Radon If these are not available, then tell me which, if any, can be used to make a star. I would prefer noble gases, and maybe other, non-diatomic gases like methane (like an inflated Neptune would be cool!). I understand that some of these may fuse to become heavier elements, which cause stars to explode. On top of this question, I would like to ask; If these are possible, then how long would they last? this one is fully optional, but if you can answer it, please do. [Answer] Fusion in stars generates energy only when the binding energies of the resulting (fused) nucleus is less than the combined binding energies of the "ingredients". Broadly speaking this means that a star made up of elements up to and including Iron generates more energy from fusion than it uses up from gravitational pressure. Once you go beyond Iron (with a few exceptional cases) the energy the star generates is not enough to prevent gravitational collapse. The details are somewhat more complex, but you'd need to get into pretty heavyweight (and long) physics to understand them and the net result won't be much different. So while you can in principle manage Oxygen, Nitrogen, Neon and Argon (all before Iron in the periodic table), Radon is not going to work. You should, however, note that their no natural process (I can imagine) could generate a large enough and concentrated enough amount of these heavier elements without a great deal more Hydrogen and Helium being in existence at the same time. But even when a star does "run out of fuel", that typically does not mean it has run out of Hydrogen. Most of the hydrogen is outside the core where fusion takes place and even when a star "explodes" after the collapse it will be mostly scattering "left over" Hydrogen and not heavier elements. The next generation of stars will be created by collapse of the resulting nebula and these will be made up mostly of Hydrogen. I would then say that there is a minute possibility that these type of stars could form. I could never say it's impossible, but it's extremely unlikely in the universe as we see it today. > > If these are possible, then how long would they last? > > > In general lighter stars last longer than heavier ones. In main-sequence stars [red dwarfs](https://en.wikipedia.org/wiki/Red_dwarf) will outlast all other stars by many orders of magnitude. The Sun might last a total of maybe 12 billion years, whereas a small red dwarf could last trillions of years. I don't have any specific links to how long stars of your type could last beyond that. Think billions of years for stars as marge as the Sun, but much, much long for stars near the threshold for this type of star to exist at all. Smaller is better for longer life is the (very rough) rule of thumb. The actual mass threshold for these types of fusion is harder to know. Red dwarfs are hydrogen fusers (like our Sun) and require a minimum mass of about 0.07 Solar masses, but stars fusing heavier elements require more mass to ignite such self sustaining fusion (but do not require as much mass to sustain it because temperatures increase in the core after ignition). A guess would be 0.15 to 0.5 Solar masses to for these "heavy element" stars to ignite. [Answer] White dwarf stars may already fit your criteria. They're fairly common, extremely long-lived (trillions of years), and, most importantly for your purposes, made mostly of carbon and oxygen. Larger-mass white dwarfs can also contain large amounts of neon and magnesium. Unfortunately, elements heavier than that aren't possible in this case, since if the star gets any more massive, it will become a neutron star instead (at which point the notion of the star being made of elements at all breaks down). If white dwarfs are too mainstream for your purposes, the amusingly-titled paper [Some Stars are Totally Metal](https://arxiv.org/abs/1406.5509#) suggests that turbulence in stellar nebulae can cause heavy-element debris to cluster in sufficiently high densities to ignite stars. It suggests that about 1 in every 10,000 stars forms this way. This might be your only way to see high quantities of something like calcium in a realistic star (noble gases would still be very uncommon, since they wouldn't form heavier dust particles in the first place). This is a relatively new concept, so I'm not aware of a lot of theory that has tried to precisely map out the concentrations of various elements in these 'metal stars.' However, the article suggests that carbon will be especially abundant, though there's still going to be a lot of hydrogen and helium in there. In addition, the paper predicts that these stars will most likely only last on the order of a few million years before collapsing into white dwarfs. [Answer] From [Professor Barbara Ryden](http://www.astronomy.ohio-state.edu/~ryden/ast162_4/notes15.html): For instance, consider the stages in the life of a 25 Msun star: * Hydrogen fusion lasts 7 million years * Helium fusion lasts 500,000 years * Carbon fusion lasts 600 years * Neon fusion lasts 1 year * Oxygen fusion lasts 6 months * Silicon fusion lasts 1 day [Answer] # What can a star be made of? A star's composition is limited by the elements that exist in significant quantities in the universe. These include primordial elements - hydrogen, helium and lithium - as well as heavier elements formed through nucleosynthesis in stars, supernovae and certain rare processes like cosmic ray spallation. This narrows down our options considerably; [hydrogen, helium, oxygen and carbon are the four most abundant elements, by mass](https://www.annualreviews.org/doi/pdf/10.1146/annurev.astro.46.060407.145222), in the interstellar medium. Radon, to use one of your examples, simply doesn't exist in significant amounts. We also can't have molecules like ammonia (to use your example) as part of a fusion pathway. At the high temperatures at which fusion takes place (well over $\sim10^6$ Kelvin), molecules aren't even able to form; the metals that do exist in stars, like titanium oxide, are only found in the cool stellar atmospheres of the least massive stars. Even molecular hydrogen can't survive in the core of a cool star, let alone a star hot enough to fuse heavy elements. We're even further restricted in our choice of elements because not all fusion reactions are exothermic, or energy-releasing. Famously, iron (and nickel) fusion consumes more energy than it releases, although [it still occurs inside the most massive stars](https://astronomy.stackexchange.com/a/11888/2153) for very brief periods of time. We need our star to be supported by exothermic nuclear reactions. At typical temperatures in a star's core ($\sim10^6\text{-}10^9$ Kelvin), several types of processes dominate in different regimes. The elements typically fused are carbon, neon, oxygen and silicon. Other elements aren't going to be able to release energy in significant amounts through realistic fusion pathways. ### Interlude: The alpha particle problem One issue here is that many of these reactions either produce or consume hydrogen or helium. For example, one of the main oxygen-burning processes produces silicon and helium: $${}^{16}\text{O}+{}^{16}\text{O}\to{}^{28}\text{Si}+{}^4\text{He}$$ In fact, helium nuclei (also known as alpha particles) play key roles in the fusion of many of these heavy elements, including the production of nickel and iron. This means that you do need some helium in your star for fusion to be significant. # How can you form a heavy-metal star? Your best bet is to try to make a star out of one of the lightest stable, easily-fusable metals: carbon. It's a reasonably common elements that's produced regularly by massive stars, and the interstellar medium is enriched with it by supernovae. Furthermore, carbon fusion can happen at temperatures just under $10^9$ Kelvin - easier to attain that the conditions required to fuse neon, oxygen or silicon. At low carbon abundances, when helium is present, the dominant pathway is $${}^{12}\text{C}+{}^4\text{He}\to{}^{16}\text{O}+\gamma$$ where an oxygen nucleus and a photon are produced. However, when carbon is much more common, a different net reaction occurs: $${}^{12}\text{C}+{}^{12}\text{C}\to{}^{20}\text{Ne}+{}^4\text{He}$$ creating neon and an alpha particle. This is the reaction most likely to happen in your star. Before trying to form a star devoid of hydrogen and helium, I think it's instructive, for a start, to look at [extreme helium stars](https://en.wikipedia.org/wiki/Extreme_helium_star), part of a broader class of hydrogen-deficient stars that includes R Corona Borealis (R CrB) variables and AM Canum Venaticorum (AM CVn) stars. These are all stars with essentially no hydrogen; instead, they're dominated by helium envelopes and cores of heavy metals. Extreme helium stars, in general, form through one of two types of processes: * Double-degenerate mergers, where two white dwarfs merge and the resulting product is hot enough to undergo fusion. For instance, the most likely model for the formation of R CrB variables and some extreme helium stars comes from the collision of a $0.6M\_{\odot}$ carbon-oxygen white dwarf and a $0.3M\_{\odot}$ helium white dwarf. * Shell fusion processes, such as a late thermal pulse or a dramatic shell flash, that involve the rapid conversion of hydrogen into helium, leaving behind a highly hydrogen-deficient star. Obviously, this requires a progenitor with non-zero hydrogen abundances, but the result clearly has negligible hydrogen. You might be wondering why I bring these up; after all, the products still have helium. However, it seems reasonable that analogous processes could happen that yield stars deficient in helium, too. Let's look at what happens if we consider the double-degenerate model - with a twist. If both of our white dwarfs are carbon-oxygen white dwarfs, deficient in helium, there's the possibility that a merger could form a star that is now purely heavy metals. The problem is that to produce the white dwarfs required for the collision, you need progenitor stars of intermediate masses (say, $\sim5M\_{\odot}$). Massive progenitors may yield massive white dwarfs, and so these carbon-oxygen white dwarfs could be $\sim0.6\text{-}0.7M\_{\odot}$, meaning that the resulting product will be near the Chandrasekhar limit and thus highly unstable. It shouldn't be a surprise that white dwarf mergers are now being studied as the progenitors of many Type Ia supernovae. [Answer] Natural stars start out as hydrogen (protons and electrons), since that is basically what the universe is made of. When the star is sufficiently big and hot, protons fuse to make deuterium; once there is enough deuterium, some deuterium nuclei will fuse to make helium; and so on, all the way up to uranium and beyond (in exponentially tinier amounts). Whether fusion is sustainable for a given element is a different question. The rate of fusion for a given element is correlated with pressure and temperature, and inversely correlated with atomic number. For a star to be stable, it has to release enough energy from fusion to compensate for the heat it's constantly radiating into space. Achieving this equilibrium with heavier fuels requires hotter, denser stars, and with elements heavier than iron it cannot be achieved at all, since fusing those nuclei results in a net loss of thermal energy. However: 1. a star can be in an unsustainable transition state for many years before it collapses; and 2. heavier nuclei do still undergo fusion, even if it doesn't contribute to keeping the star alive. Were this not the case, we wouldn't have naturally-occurring uranium, or gold, or zinc. Even healthy stars contain some amount of heavy elements (though I believe most heavy-element production is thought to occur in dying stars). So that in itself would not be surprising. What would be surprising is if the proportions of different elements implied that the star was not all hydrogen to begin with. In nature, the only way a star is burning a high proportion of second-row elements is if it is enormously heavy and on the point of becoming a supernova. But if you could figure out a way to start with just lithium or beryllium, I would guess it is possible to set that up so that the star lives for millions of years at least. But I would guess that if it was all-oxygen or all-neon, that would be less like a "dense normal star" and more like a "skinny supernova" that would quickly collapse. (NB molecules, like methane or O2, are not meaningful in this context; at star temperatures, chemical bonds don't exist, it's all just atomic nuclei and electrons). ]
[Question] [ As clarification we're talking about those common fantasy healing potions that recover health over time and their scientific plausibility. Here are some results from my research on the subject: Modern medicines are pathetic compared to even the weakest of health potions. Medicines reduce the amount of external influences such as bacteria from slowing down healing process unlike health potions which directly increase the regenerative performance. Law of conservation is rather problematic. Potions could carry construction materials into body, but larger wounds would require tremendous amounts of matter not obtainable from small dozes. This matter could be drawn from surrounding tissues, but would require obscene amounts of food to maintain physical mass and constant drain would cause serious health problems later in life. Main problem however would be regeneration. I've never heard of anything which would hasten regenerative speed aside from stem cells but even them wouldn't survive digestion and make it into bloodstream intact. So to summarize: ...if healing potions were scientifically plausible how would they work? [Answer] The common misconception with healing potions is that you have to drink them. The better way would be to directly pour the healing potion on the wounded area to allow it to directly interact with the wound and begin the healing process. Otherwise you will need to wait 30+ minutes for a potion to take effect because it will need to survive through the stomach and get digested before it takes effect. So your healing potions are basically stem cell and nutrient soup. When it gets into contact with a wounded area, causes the bodies natural regenerative abilities to speed up and the cells feed of the nutrients included in the potion to allow them the grow quickly and beyond the capabilities of the human body. If you want more high tech, you could throw in a bunch of nano bots into the potion and they will help reassemble the damaged body part stitching your body back together using stem cells and whatever other nutrients and flesh you decide to throw into the potion to give it a nice rich red color. Drinking a potion is too old school. Apply potions directly to wounds for best effects. [Answer] Nanites You swallow, inject or even pour them into the wound and they go to work sealing off the damaged areas and rebuilding the damage. To prevent potential problems, they have a limited battery life once activated and no self replication ability so they heal for a short time and then stop. See [nanites healing](https://www.indiatoday.in/education-today/gk-current-affairs/story/nanobots-for-human-body-faster-healing-brain-1065771-2017-10-16) [Answer] # Stem cells > > Stem cells have the remarkable potential to develop into many > different cell types in the body during early life and growth. In > addition, in many tissues they serve as a sort of internal repair > system, dividing essentially without limit to replenish other cells as > long as the person or animal is still alive. When a stem cell divides, > each new cell has the potential either to remain a stem cell or become > another type of cell with a more specialized function, such as a > muscle cell, a red blood cell, or a brain cell. ([ref](https://stemcells.nih.gov/info/basics/1.htm)) > > > The magic part hasn't panned out, but the hope with stem cells is that there will someday be a method of using them to regenerate damaged cells in a targeted way. So far there have been doctors and [clinical trials](https://stemcells.nih.gov/trials.htm) which have showed promise. "There are over 5,000 registered clinical trials involving stem cells research on ClinicalTrials.gov, with new clinical trials in this field being offered every day." A [list of trials](http://stemcellsportal.com/stem-cells-translational-medicine-clinical-trials-portal) for Stem Cells and Regenerative Medicine is available. > > Perhaps the most important potential application of human stem cells > is the generation of cells and tissues that could be used for > cell-based therapies. Today, donated organs and tissues are often used > to replace ailing or destroyed tissue, but the need for transplantable > tissues and organs far outweighs the available supply. Stem cells, > directed to differentiate into specific cell types, offer the > possibility of a renewable source of replacement cells and tissues to > treat diseases including macular degeneration, spinal cord injury, > stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid > arthritis. ([ref](https://stemcells.nih.gov/info/basics/7.htm)) > > > The potential is there but we don't yet know how to really make them work. It's reasonably to think it's scientifically possible though. Will this be a "healing potion"? Probably to some degree (to a small extent, stem cells already are). Will we have the magic potion you allude to? Probably not, but it's easy to imagine a future where it happens. ]
[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/139134/edit). Closed 4 years ago. [Improve this question](/posts/139134/edit) Preface: This is a very abstract question since it really would depend on the worldbuilder, and the type of setting they are trying to build. --- ### In Established Works In works such as Lord of the Rings, kingdoms, or at least cities are mostly separated by race. In the real world, "kingdoms", or rather, countries, are separated by language primarily (with some very fuzzy lines), as well as just overall history, but definitely not by "race", at least not primarily, and not as a constant rule. In works such as A Song of Ice and Fire, "kingdoms" are split primarily by alliances and geographical landmarks (The Narrow Sea, The Wall, etc). Since "races" aren't very prominent, and even where they are (Such as humans and giants beyond the wall), they coexist just fine. In D&D it seems that all of the main/original races are pretty common in all parts of the world. Even in places such as Mithral Hall, while dominated by Dwarves, Humans make up 4% of the population. Other cities, such as Waterdeep, the population is even more diluted. These are just cities though (even if they have their own high level form of government), if we look at the overarching kingdoms, rather than just cities, the races begin to blend even more. While it seems that mountains are mostly inhabited by Dwarves, and forests by Elves, Faerun is mostly diluted like the world out here is. --- ### Soft Rules From the worlds above, it seems that some abstract rules that they set are as such: * Borders are set by conquest and alliances. * Some fantasy races may choose (or are forced) to live in a certain environment, but wouldn't necessarily create a kingdom/country around that setting. * Language and culture may be a primary reason of divides, but with conquest and time, language and culture can change. --- So what did I get wrong? What have I missed? Are there other important rules to take into account that you can think of when building a fantasy society? What are some obscure (or common) events that may break some or all of the outlined rules? Bonus: What effects might magic have on any of these rules? (This might warrant its own question, depending on the magic system) EDIT: You're all correct in saying that establishing a kingdom is simple, it is a king ruling over a place. The question was supposed to invoke a discussion, not literally about the logistics of creating a kingdom, but how fantasy aspects would influence the emergence of kingdoms in all aspects; literally, geographically, historically, etc. But it should also call forth a question of society and how multiple races would coexist, and how they would come together to create countries/kingdoms. Was Toliken more correct by separating these races into their own kingdoms, or would it be more believable/realistic to have these races and societies mingle a lot more than that like in the world of Faerun of D&D? [Answer] Kingdoms are generally defined by distance from the capital and resources. The more resources you have, the more territory you can patrol/hold. That is because you have to feed any people who aren't generating resources. Also, better resources can make your troops more effective in battle and/or faster. This can be self promoting since better resources lets you range farther, which lets you bring in more resources. Kingdoms tend to fracture when they get too big (arguably 1 month travel time). When the travel time is that long, you can have locals who can get away with stuff knowing that it will take at least 2x travel time for any kind of response. One way around this is to become an empire with multiple kingdoms. This solution isn't perfect (how many empires still exist?) but it can put off the breakup. Also, if another kingdom who's border is within your maximum kingdom size, then there will likely be border conflicts over resources in the overlap. Kingdoms generally start out from a single group/tribe and expand. As they conquer other groups that are within their range, they will either genocide or incorporate the other group. How they are incorporated is dealer's choice. The Romans incorporated people in a variety of ways (slaves, free workers, lesser nobility). If a kingdom is part of an old empire or the remnants rebuilding from a fallen empire, there may be several groups working together already. Otherwise, any incorporation will be happening in story time instead of backstory. Magic will do what technology did. It will expand the size of the border. With troops having more fire power and travel and communication times being shorter, the borders will be farther out. If the other kingdoms have magic that will be the only real effect on this aspect of the kingdom. Any other kingdom without magic will be incorporated into the kingdom with magic unless the magicless kingdom doesn't have anything the other kingdom wants or is otherwise undesirable. Edit: additional info About relations between different groups. While there are exceptions you might want to consider these parameters: Does the other kingdom have something you want? Yes: Are they too much trouble to conquer? Yes: trade, No: conquer No: Are they in the way? Yes: conquer, No: leave alone [Answer] In the real world what limits a nation beyond outside forces is how much control can you exact upon your subjects? On one end of the scale we have a tribal leader and on the other side a church appointed descendants of the gods. A tribal leader has about as much control as he and his loyal band of warriors can exact directly upon his subjects. His realm will be small, he would need to travel it rather frequently or at least use the threat of a visit. On the other side we have a person who derives their authority from divine rule backed by a religious institutions who enforced his claim of divine heritage. He will gain additional control from both personal fear of angering the gods and a nationwide religious institution who can preach about obeying your king. His realm can be many times larger as it's not tied to his direct physical presence. His succession would also be much more stable as his base of power won't die with him. A tribal leader would take the majority of his power with him into his grave. Unless his son has martial prowess and a loyal base the realm will likely crumble. So the more your power is in institutions the larger you can grow. Using a medieval feudal system is a good way to do this. You create a warrior caste with special privileges, that you then outsource your daily ruling to. Combine this with a religious system that enforces your rule and you got a decent system. So historically what made kingdoms the way they were was claims, power to execute them and natural borders. Languages are not really a barrier and more a result of borders then the other way around. When you conquer you tend to conquer till you hit a natural border, a river, a [mountain range](https://www.worldatlas.com/aatlas/infopage/pyrenees.gif), a marsh. You want something that is hard to cross with an army at high speed. You want plenty of time for a warning. The Roman empire in northern Europe [ended at rivers](https://en.wikipedia.org/wiki/Roman_military_frontiers_and_fortifications). In the British Isles they lacked a natural border so they build a wall and decided to not conquer north of it. [![hadrians wall](https://i.stack.imgur.com/EOlp2.jpg)](https://i.stack.imgur.com/EOlp2.jpg) The same thing will apply to your fantasy kingdoms, armies will conquer all they can till they hit a natural border. If it's to hard to reach the next natural border they'll eventually retreat. It might take a few years, it might take a few months but they'll give up trying to hold it. Unless there ideological reason to not mix your races will mix within your borders. If the elves decide dwarves are filthy earth diggers that must pay a hefty extra tax most dwarves will probably avoid living in elfish lands. But unless it's actively enforced your races will mingle when they can. Being a medieval setting they won't travel far. Most won't even be more then a few days from their birthplace. But soldiers will settle after campaigns, certain groups will be pushed out of their home and travel till they find a new spot. Look at medieval Spain, Jews in medieval Europe or the Bactrian Greeks in Asia. To summarize, I think your conclusions are wrong. Natural borders and limits on control are far larger factors then culture or language. The Romans, Arabs, Huns and Mongols conquered large portions of the world without speaking the local language. Usually after conquest the ruling elite switched to the language of the conquerors. [Norman French in England](https://en.wikipedia.org/wiki/Norman_conquest_of_England#Language), Arabic in Andalusian Spain, Latin in Gaul, etc. Languages differentiate when new things are discovered that must be named or when another language is forced upon it. Like with conquest by a foreign power. At a natural pace not much will happen quickly. ]
[Question] [ Consider a planet which is entirely Earth-like. Same mass, same rotation, etc. But in this world, resource-rich objects are suspended by some phenomenon at varying altitudes up to 200km above sea level (effectively from the surface, since the highest point, Mt Everest, is >9km above sea level). Clarification: some are at 200km, some are at 5km, 50km... They are fixed relative to the planet's rotation, thereby always being above the same point on the surface. The resource is valuable, and must be harvested by a machine such as a modern backhoe loader (e.g. the arm on the back of a JCB digger). How might a society with approximately our level of technology exploit these resources? Up to perhaps ~10km, specialized helicopters or airships could be flown. Anything at or above the Kármán line would pose a problem: the orbital period is 1 day, but the altitude and hence orbital velocity is far lower. An asteroid in a Keplerian orbit would be straightforward, if not cheap to harvest: a spacecraft could match its orbit. But in this case, if a regular spacecraft or spaceplane attempted to orbit at the same altitude, it would fly past the target very quickly. Between the limit of helium balloons and the edge of space, there may be other problems. How could people harvest the resources of the higher objects? [Answer] Ballistic Trajectories This is actually easier than getting to space. Space is hard because you have to go really fast to be in an orbit. Achieving orbital height is easy. Achieving orbital velocity is hard. So you build a rocket right beneath your "geostationary" resource, and give it just enough fuel to reach the height you need. Your rocket releases a payload, which has exactly zero velocity when it reaches your resource. The payload grabs on to an outcropping, or uses a harpoon, or otherwise attaches itself to the valuable thing. Now, either the magic that keeps the resource in the air keeps your payload in the air, and it starts harvesting, or the whole thing is now too heavy for the magic and it falls towards earth, in which case the payload controls the landing. This is hard, but not as hard as actually harpooning an asteriod, which we have done. [Answer] Send impactors against them to reduce their momentum. They will lose altitude. After they descend some the increased atmospheric drag will cause them to deorbit and crash. You'll just need picks and shovels then. ]
[Question] [ I'm new here but I've been a worldbuilder for the last decade or so. I'm pretty late to the 'mapping out your country' party and I've only been at it for about 8 months, but I'm starting to see some progress. However, I appear to have a bit of a deficiency in my knowledge of rivers that threatens to jeopardize the realism of the whole project. I'm attaching a few examples (in these screen grabs the effects that you see in the above map are off, so everything looks a bit crude, bear with me) of rivers that in particular stand out as ones that don't look right, along with distance measurements of what you see on-screen, to give you a sense of the scale I'm working with. [![enter image description here](https://i.stack.imgur.com/h9AoQ.png)](https://i.stack.imgur.com/h9AoQ.png)(also [here](https://www.dropbox.com/s/4m70lipx9wdun7m/river%20question%20a%20fixed.png?dl=0)) [![enter image description here](https://i.stack.imgur.com/hzkot.png)](https://i.stack.imgur.com/hzkot.png)(also [here](https://www.dropbox.com/s/fqimf8zjruf68kf/river%20question%20b.PNG?dl=0)) Nothing you make is ever truly finished, so with that in mind there is very little in the country that I am 100% married to, but if I'm going to have to redraw the rivers again, this time I'd like to get it right. With that in mind, I wanted to ask: what principles I should bear in mind when drawing rivers? Obviously I have a basic grasp of the fundamentals (water flows downhill down the steepest slope possible, rivers merge, not split, etc etc) but my knowledge is pretty lacking beyond that Thank you for any and all assistance that you may be able to give me! [Answer] Some incomplete rules: * The faster water is flowing, the less likely it is to turn: Flat land means winding rivers. * Rocky land means more turns. * When water slows down, it loses any silt it is carrying, and it can wind, or even split, as it does at the Danube delta. * Water may pool if it cannot immediately get through, but it almost always finds a way to the sea, or at least into an endorheic basin, such as the Dead Sea. * Rivers often converge: two rivers form one. * While relatively rare, rivers can diverge: one river forms two. [Answer] I see that your rivers have a tendency to flow along the foot of your mountains. This is not very realistic, in real geography rivers tend to be in the middle of a plain, maybe meandering, maybe straight. Straight rivers come either from a fast flow caused by a strong height difference or from regulation by human activity (the landscape looks industrialised, so river regulation probably happened). The course of the Lemonwood river near Wolesey looks unnatural, I'd expect it to flow east of the hills and through Florg. There is a watershed near the number `7` on your map: West of it the river flows northward, East of it a river flows southward. This can happen, but it is a remarkable geographic feature in itself. When the rivers are navigable, people may build a canal across this watershed. I assume that Avon Lake has a higher level than the lake/sea at Caulmouth, so it is not directly connected to that part except by river Caul. BTW, the placement of some of the big cities in the mountains also looks suspicious and calls for an internal historical explanation. [Answer] The direction of your rivers is a function of your topography and the amount of water you have flowing over it. A tiny amount of water doesn't flow because it is absorbed or evaporates; a massive amount of water is a lake or sea. The assumption must be that you are moving a moderate amount, a "river-making amount," of water across the land. Your river starts up and heads down; Pardon the anthropomorphizing but it does not "know" where the sea is. Place your elevation changes where you want/need them to be. Figure out where your water comes from (rain, snow melt, etc.) and then let your flow choose the most direct route down. Pooling water will "choose" to flow if it has the option. There are at least two other considerations: obstacles and ice. Your rivers will be turned by stone which is, of course, impermeable. And while ice does flow in the form of glaciers, glacier flow is an entirely different question. [Answer] You have two rivers, marked 190km and 203km, that flow alongside your mountains, which is very unusual, mountains mean high ground which means the land around them should be raised as well, meaning water should flow away from hte mountains not along them. Its fine when you have mountains on both sides but for those two you have mountains on one side and open plains on the other, they should flow closer to the center of the flat lands. Worse they bracket the same mountains, one or the other might be believable due to a faultline mountain with a prevailing slope to the ground but that won't work for both. 190km is especially bad since there is a lake right next to it meaning there is lower land out their. So you should either move the river or have some indication of raised land like hills between them. As a second complaint the lake in the plains I mentioned near 190km connects to nothing, which might be believable in a lake in the center of the mountains but on hte open plains something needs to feed and drain it. So your best single move overall is to move 190km river to intercept the lake. ]
[Question] [ Humans can speak making precise movements of our tongues, teeth and vocal chords. I want a sentient creature whose carnivorous mouth-parts are completely unsuitable for speech to be able to communicate fluently with others of its species. * A trumpet can certainly make different notes by vibrating the lips against the mouthpiece whilst blowing. * A manatee can finely control its flatulence as an alternative to a swim bladder. <https://youtu.be/ktLwBHsA_vk> * Humans have been known to be able to inhale both air and water through their anus. > > The great early 20th Century French flatulist, Le Petomane, was able > to do this, ... By sucking in large quantities of air [through his anus], he was able to > perform lengthy shows on stage, and could imitate musical instruments, > farm animals, and bird songs, whistle melodies, and play the ocarina. > <https://megafart.wordpress.com/2012/02/18/is-it-possible-to-inhale-suck-in-air-via-ones-anal-opening/> > > > EDIT - On following this up, I fear the claims made above of what he could do were greatly exaggerated. The main point was that he could draw air in at will which is something most people can't. Question Could an alien anus-breather evolve to communicate entirely by taking in and expelling wind? Would it have to evolve extra appendages to do so? I'm talking about a complex language similar to that of humans. Not just alarm calls. [Answer] Totally doable. [Some animals on Earth communicate by making noises with their third eye:](https://www.sciencemag.org/news/2003/11/farting-fish-keep-touch) > > It's a little boy's dream: talking through farting. But it may be a part of everyday life for herring. A new study finds that the fish make noise by squeezing air bubbles out of their backsides. Researchers believe the noise could be used for communication. > > > (...) > > > The team noticed that herring often release bubbles from their anuses when scared or during ascent or descent. They reported this curious finding earlier this year in Aquatic Living Resources. > > > To get an even closer look, Ben Wilson of Simon Frasier University in British Columbia, Canada, set up tanks in the lab. Wilson's group videotaped the fish and correlated the bubble blowing with the sounds they recorded, which they termed fast repetitive ticks (FRTs). Wilson's group found that the herring need to gulp air at the surface for continued FRTs; when the researchers blocked the herring's access to air, the fish FRTed for a little while then stopped. The team also noted that the herring made this particular noise just as darkness was falling, when they gather. This suggests that the FRTing has a social function, Wilson and colleagues report online 5 November in Biology Letters. > > > Although related fish have been caught farting nondescriptively, these new herring FRTs are distinctive. "They're really cool signals," says acoustic biologist Michael Fine of Virginia Commonwealth University, Richmond, because they're streams of distinct pulses. > > > Your aliens could communicate by making pulses of different length and pitch. Pulse length can be controlled by regulating the amount of expelled gas; pulse pitch may be controlled by using more or less rectal length for the fart, or by controlling the anal aperture. As for how to get the air in there, use a mechanism similar to [aerophagia](https://en.wikipedia.org/wiki/Aerophagia). [Answer] While not impossible, the biggest problems with anus speaking is that the colon is designed to be filled with solid waste and you'd basically be unable to speak without purging first. A second issue is that if you are picturing a similar placement for the anus to that you find in most earth animals, you'd also have trouble speaking while moving since you have all those large gluteal muscles around it that flex and extend as you walk. If you think about human speech, it is not so much the faculty of our mouth to eat that makes it good for speech, but the fact that it ties into our respiratory system. Our respiratory system is always clear by design, and it is already very specialized at inhaling and exhaling large volumes of air for which there is not really an evolutionary pressure to cause that adaptation in the anus. While it would certainly make for an entertaining plot point, and is not entirely unreasonable that this might happen, I can think of several other ways an organism would probably have a stronger evolutionary reason to develop communication than via the anus. [Answer] A creature could communicate with its anus without the need for the anus to be too complex in terms of articulating sounds, if its anus was instead a long siphon like that of a squid, which could enhance the limited sounds with complex motions. This seems plausible, as a long siphon has many advantages and reasons to evolve it, such as being able to defecate further from your trails, being able to use it as a snorkel (if it also breathes through its anus), and simply for display ]
[Question] [ Question: Could colonial organisms form into a sentient being, something like a human, for example? Could they evolve into beings with thoughts and feelings? A race of colonial organisms taking the form of humans would be interesting... but I'm not sure if its plausible. PS: by 'colonial organism' I dont mean ants, (This type of question has been asked before), I mean [siphonophore](https://en.wikipedia.org/wiki/Siphonophorae) (this is just an example, I don't mean colonial organisms that are aquatic, specifically) type organisms, like the Portuguese man of war. Could a human-like sentient being made of these type of organisms exist? [Answer] I don’t see why not. Colonial organisms, or at least the example you gave in the siphonophores, aren’t really all that different from more complex multicellular organisms. Both types of organism arise from a single egg cell which divides to generate the rest of the organism. In both organisms the constituent parts, cells or zooids, differentiate from each other in other in order to perform specific functions. In complex animals we have thousands of different cell types that all work together. The colonial organisms are generally somewhat simpler with a few different types of zooids specialized for feeding, defense, reproduction, and movement. But I don’t see any reason why colonial organisms can’t become just as complex as multicellular organisms can. One might imagine a colonial organism that developed a zooid that served a function analogous to our nerve cells. Carrying messages and signals throughout the organism and potentially synthesizing and networking those signals into what we refer to as intelligence. [Answer] We can't say it's impossible, but we also have no examples in our planet. So we are stuck with speculation. There are philosophers who believe that sentience and consciousness (which is something different, but also interesting) are emergent properties of the brain. Some scientists are looking into this, though it seems at the moment that we might be unable to ever satisfactorily gather evidence for it. Supposing it is, it is no stretch for an artificial system to be sentient. And if such an A.I. is running on a distributed system over a network, it will be a colonial mind. And it may build a host of humanoid bodies for itself. This has appeared in literature in the form of the Geth people. Each Geth physical body is actually a server holding thousands to billions of minds that act like a colony. If such a complex system exists due to distributed computation, there is little to no reason why a natural system could not evolve in a similar way. Again, literature presents this in a work of art: Arthur C. Clarke's Rama series of books has a species that is a sentient colonial fungus. This fungus sometimes lays "eggs" out of which come some furry creatures, which are its children in a solitary (i.e.: non-colonial) generation (just like some coelenterates have alternating generations). The solitary furry animals are the same species as the fungal colony and can telepathically commune with it, and act as the fungus's avatars. Another instance of this is the fungus called Planet in Sid Meyer's Alpha Centauri. It covers the whole planet and absorbs other beings into both of its mass and conscience. Late in the story it joins with some humans in mind only, with the human bodies serving as Planet's avatars. [Answer] I am pretty sure that multi-cell organisms have evolved from colonial ones. So it could be possible. But it would be a lot harder. Humans and other advanced organisms have extreme specialization between their cells, and I bet this specialization might not be possible if every cell is supposed to be same, or at least be able to change to any other role. I think a colony organism can act as a brain given that is has enough nutrient available to let some cells focus on information processing rather than food gathering. But those pseudo-neurons will be a lot less efficient than dedicated real neurons of multi-cell organism, so your intelligent colonial will be the size of an elephant, but have intellect of a bee. Also, I really do not see how a colonial can develop conventional skeleton. Perhaps it can just absorb rocks or sticks into its body, and glue them with secretions of its cells. ]
[Question] [ In the DC universe, there exists a hero known as Sister Superior with prosthetic arms that are capable of turning into any weapon she desires. Interestingly, her arms look no different from a regular girl's arms when not transformed, save for a few seams. Obviously, having the ability to form any weapon is ridiculous, but her powers do bring about the question... Is it possible for a machine gun (a weapon Sister Superior has used in the comics) to fit inside the space of an arm prosthetic? If not, how small can it be? For the purposes of this question, assume that the prosthetic must look human and fulfill all motions of a natural arm, including bending of the elbow, wrist, and fingers. The machine gun does not have to be functional when in "human mode", but once it is transformed, no additional parts should be added for it to be used, save for a clip. [Answer] The answer to this question depends a LOT on what you mean by 'machine gun'. It's a pretty vague term, and doesn't really mean anything precise when it comes to weapons. If the question is: Would a fully automatic firearm fit inside a human's arm, then the answer is absolutely yes. The actual firing mechanism of most firearms isn't all that large relative to the size of the overall firearm itself. A couple good practical examples that come to mind are the [FN P90](https://en.wikipedia.org/wiki/FN_P90) and the [Calico M960](https://en.wikipedia.org/wiki/Calico_M960). Both are 9mm submachine guns with 40+ rounds in the magazine. Both would EASILY fit in someone's forearm with all the furniture (stock foregrip etc) removed, especially if the ammunition were being fed from a supply in the bicep. Keep in mind that these are short-range weapons that are only good against people and people-sized targets. If by "Machine Gun" you're thinking of something like an M60 that fires a MUCH more powerful round and uses a 100round belt for ammunition, then no. That absolutely wouldn't fit in someone's arm. [Answer] You gotta start with the round being used. Here is why: the round determines 2 things, the size of the mechanism, and the amount of recoil. Lets talk terms for a second. To avoid a little bit of pedantry lets get a little more specific than 'Machine Gun'. The weapon in question for Sister Superior is going to be a Detachable Box Magazine fed Fully Automatic weapon. That means that the rounds are loaded in to a metal box with a feeding mechanism. the Firing mechanism will use either the recoil of the round being fired or the expansion of gasses from firing to remove the current round's brass, chamber the next round, and fire again as long as the trigger mechanism is activated. Now that we have disposed of that little bit of trivia, lets talk about recoil. This is pretty much Newtons Third Law in Action. To oversimplify the math, The Mass of the slug times the velocity of the slug leaving the barrel is going to have an equal and opposite reaction. The mass of the weapon (usually many many times the mass of the slug) travels in the opposite direction and will impact over a much greater surface area (usually the butt of the rifle) repeated each time the thing fires. The felt recoil is what is left over after whatever energy is dissipated in the mechanism of the weapon. Remember you have a tiny chunk of lead going one way, and a large chunk of other metal going the other, spreading the impact over a greater surface area. This is why firing powerful rounds can bruise the heck out of your shoulder. Given that this weapon will be impacting a surface area that is pretty small (the size of the cross section of her normal arm's stump) you want to fire something that has less recoil. 9mm is a common round for many compact submachine guns like Uzis and Mac 10's. They are hard to control when firing on fully automatic, because the mass of the weapon is low. The recoil comes back along the mechanism and tries to 'lift the barrel because the wrist becomes a pivot point. So I'm thinking that Sister Superior's arm gun may not have exactly the same problem, but it's not a trivial thing. Next you have the problem of the mechanism's size. It has to be small, otherwise Sister Superior will have to change her name to Sister Popeye. The Mechanism of a 9mm fully automatic 'might' be made small enough, Anything bigger goes right out the door due to recoil problems. The mechanism for something smaller might be better. I would think maybe a .22 Mag would be almost Ideal for many reasons. First, .22 Mag rounds are small. You can fit a lot of them in a small magazine. Look at this [weapon here](https://www.keltecweapons.com/pistols/pmr-30). It is roughly the same size as a mid size 9mm pistol. The difference is that it holds 30 rounds in the magazine where a similar sized 9mm would hold maybe 9 rounds. 9 rounds, reload, 9 more reload would be silly. 100 round magazines for 9mm exist, but when loaded, they are pretty heavy. That's going to make it harder to maintain her point of aim. .22 Mag rounds will be much much lighter. Recoil from the .22 Mag is pretty low. It's enough to eject the brass and load the next round, but you don't need huge, heavy components to do so. The .22 Mag can also be lethal at close range. She is not looking to pick someone off at 500 meters with this thing. I can see Her weapon being chambered in .22 Mag. She can carry a lot of Box Magazines filled with 30 rounds each, and never disturb the lines of her Habit. The mechanism would be small enough to fit in her 'forearm'. The recoil will also not pound her stump to jelly or knock her over. She'll be able to aim without problems too. [Answer] A quick search yielded [this video about a fully-automatic CZ-75 machine pistol](https://youtu.be/6eXEXTWDh8o) which has a barrel length of 5.77 inches and weighs 2.47 pounds. It looks like it fires 9mm rounds, which are respectable for a pistol. I found figures online that put the average length of an adult woman's forearm at about 10 inches, so it fits lengthwise. Depending on how the cyborg's radius and ulna are positioned, you might be able to make it fit. I assume you'll get rid of the pistol grip and maybe modify the trigger to be more compact. If your cyborg were to extend the mechanism out parallel to her arm, I guess she would use the other hand to insert a magazine and pull the trigger. Not very practical, maybe, but it would still put a hole in a target. ]
[Question] [ A large group of billionaires, engineers, pilots, and volunteers come together to announce the creation of an aircraft-based civilization. Here, people spend most of their lives aboard an aircraft, whether it's an airplane, seaplane, helicopter, gyrocopter, cyclocopter, hot-air balloon, or airship. For them, spending time on the ground or at sea is as rare as spending time in the air is for us. The group tries to get its society recognized as a nation, but it inevitably runs into problems with airspace violations. The team has a few options... * Limit operations to international airspace. * Engineer your aircraft to fly as high as possible, and hope that Earth's nations don't mind. * Ram through a massive reform in international law that significantly drops airspace boundaries. The upper limit of modern airspace is vague, but it's often set to the Karman line and that won't cut it. Economically, there isn't anything of value in the air. The new civilization will be extremely reliant on imports, but it has to find a way to pay for all of that. Perhaps people can make money by transporting cargo, conducting research, and serving as aerial mercenaries. I get the feeling that this won't nearly be enough, though. It's a longshot, but maybe the country can apply for international aid. Also, I don't think it's ideal for their aircraft to have to land in a foreign airport every few hours. For this to work, there needs to be an airport in the sky, perhaps made up of a fleet of airships. This is where the engineers come in. [There's a Wikipedia article on airborne aircraft carriers](https://en.wikipedia.org/wiki/Airborne_aircraft_carrier), but apparently one of these has not existed anywhere in the world since 1935. Besides that, there's the problem of landing an airship on an airship. How feasible is it to build a flying airport today? [Answer] ## Physical Concerns If you have already read about lighter than air vehicles (LTAV) in the 1930s, you know that they are very vulnerable to weather. This is why, to my understanding, they were abandoned. However, predictive weather radar has improved significantly in resolution and accuracy. I can imagine the floating civilization always moving to stay in the clearest part of the weather track. [Interactive Future Radar](http://www.iweathernet.com/interactive-radar) Another concern is air envelope weight. I'm going to imagine you using handwavium for your envelope : maybe some next-generation waterproof weaveable aerogel. Even neglecting infrastructure, depending on the height of your floating civilization, you will need a very large displaced air volume. * 1,000 feet: 1,700 cubic feet per hundred pounds * 5,000 feet: 2,000 cubic feet per hundred pounds * 10,000 feet: 2,500 cubic feet per hundred pounds ## Political Concerns The altitudes at which an LTAV city would work physically are in the middle of the aviation range of altitudes. Internationally, certain paths have published altitudes and there are levels of separation between traffic. It may be possible for your civilization to negotiate to have a Notice to Airmen (NOTAM) issued directing flights away from the city. [Flight Levels](https://en.wikipedia.org/wiki/Flight_level) I imagine most nations would want to refuse a request for a city to float over their land. However, if the city is organized by an institution that does business and has leverage almost everywhere (think of an Exxon or other multi-national energy company), then I can imagine them being able to negotiate fly-over requests with most countries. ## Economic Concerns If the city was an international station, like the International Space Station or international antarctic stations, then it seems plausible that universities and governments would provide most of the operating income for the station. As a suggestion to what kind of research a floating city might accomplish: they could focus on climate research or climate change research, or maybe are evaluating the effectiveness of political/technological improvements that are supposed to reverse climate change. The city doesn't have to be the best solution to the problem. We live in a political world where the best solution is often not the one we go with. ## Operating Costs Replacement helium will likely be your most frequent material cost. At $450 USD per 1,300 cubic feet according to [Quora](https://www.quora.com/How-much-would-1-300-cubic-ft-of-helium-cost) your cost would be: * 1,000 ft: $575 per hundred pounds of weight being carried by the city * 5,000 ft: $680 per hundred pounds * 10,000 ft: $865 per hundred pounds (all values rounded) According to this [YouTube answer](https://www.youtube.com/watch?v=RJvNb-Kd8fI), and assuming your LTAV helium envelope was made of something similar to Mylar in impermeability, the civilization would need to replace the whole volume of helium approximately every second week. That would make annual helium cost $15,000/$18,000/$23,000 USD for the three altitudes mentioned before. Multiplied by the weight of the rest of the settlement in hundreds of pounds. Assuming the flying city had the $125 million per year [maintenance budget](https://en.wikipedia.org/wiki/International_Space_Station_program) of the International Space Station, how big could the aircraft based civilization be? Between 418 tons at low altitudes to 280 tons at the higher altitude. ## How Much Will Infrastructure Weigh Again, excluding the helium envelope, it would be nice to know what is required to sustain residents at this high altitude civilization. It will be cold and air will be thin. A good example of structures built for this purpose would be the [McMurdo Station modules](https://en.wikipedia.org/wiki/McMurdo_Station) in the Antarctic. These had to be able to do the job, but also be small enough to fit into the 30,000 pound footprint of a C-130 delivery vehicle. Given an International Space Station maintenance budget of $125 million per year to spend on helium, you could have between 18 and 27 McMurdo Station style modules for your floating civilization. You would probably want to cut out an allowance for aircraft to arrive and depart the floating city. Even at 10,000 feet altitude, the aircraft based civilization is within reach of propeller aircraft. A few aircraft weights for reference: a six-passenger [Learjet 24](https://en.wikipedia.org/wiki/Learjet_24) is about 6.5 tons. An [Airbus A300](https://en.wikipedia.org/wiki/Airbus_A300) (323 passengers) weighs about 70 tons. Also, you would want weight for people and supplies. ## Summary From a hard-science perspective, you might really want to think through it. Especially the material holding all the helium keeping the city afloat. It would be very easy to drive up weight and cost there. It is realistic that someone motivated with a will to make it happen and good international connections could make such a place possible. Yes. [Answer] ## They cannot attain self-sufficiency ...and thus will fail. Civilization is heavy. Very very heavy. Earth's atmosphere doesn't like to support heavy things without lots of energy expended. As an example of how heavy, a single 1000-ton press used to make kinds of useful stuff, weighs 230 tons. This is just the equipment itself. This is very close to a Boeing 747 at 202 tons. While the payload of a freighter 747 is enough to lift the mass of the press, it can't support the huge loads exerted when the press is in operation, nor carry any of the materials that the press will operate on. The inability to create new planes/airships without ground industry means that this newly declared nation will fail as soon as some other nation(s) decide to deny them access to their airspace and ports. Without fuel, they will be grounded in days. ## Political Considerations In order for a country to be recognized as a country, other countries have to acknowledge it as such. This acknowledgement is based on many complex factors but basically amounts to "Can I conquer you and would it be expensive to do so?" and "are you a peer?" if the answer is "Yes and it's easy" and "No, you're not", then no one will acknowledge you. Most any modern airforce could knock this new country out of the sky. Further, statehood is dependent on controlling land which your new country by definition cannot do. Thus, you lack standing to gain entry into the gentlemen's club that is international politics. Also, acknowledging an entirely airborne country sets some unwelcome precedents. If any rich guy can build a big plane then declare themselves sovereign, then they'll all do it. This adds complication to an already complicated international environment. These nations also know that losing the ability to control the world's richest people will only lead to problems. ## Durability of Airframes Each aircraft has a service life of so hours of flight time. For commercial aircraft, this is measured in flight hours or cycles (take-off, fly, land). Aircraft that are constantly in the air will chew through those cycles very quickly. There's too many ways for this to fail. Nature's best flyers still land to lay eggs and take a breather. [Answer] An aircraft based nation wouldn't work, because the lively hood of your nation would be directly tied to the amount of fuel imports you could get from all other nations. You provide no direct benefits, only benefiting the wealthy who live up there and act as basically a huge money sink. Its also going to be freezing up that high and everyone who wants to go outside would probably need to wear a insulating suit and a gas mask so they can breath. Basically you have a giant floating hotel where rich people can socialize, but why would they need to do that when they can just fly around in private jets with the rich people whose company they already enjoy? I recommend going up even higher, into space and constructing a space elevator. At the top of your elevator is basically a huge space platform which forms a new nation that acts as the gateway to space for all ground based nations. This would bring you a ton of income as it drastically reduces the cost to launch a space craft (You could elevator the spacecraft up, or construct it up there). The construction of your new nation would also be easier since you can use your own space elevator to lift everything up, and the view would still be amazing. I believe the idea is considered to be feasible due to the strength of carbon nano tubes, but no one is able to construct a carbon nano tube strand longer than a meter yet. <https://en.wikipedia.org/wiki/Space_elevator> [Answer] I think there needs to be a true need for such a thing. The cost of such creations is going to be prohibitive. Wanting to do it just cause it'd be so cool doesn't seem like enough. It might work if these billionaires were only making flying mansions for themselves, but they likely wouldn't require the kind of changes to the law you're talking about. There may be a number of these shy-homes, and they may want to buy a large area they could own, and freely fly over, but not a whole nation. Perhaps an airborne culture, as in a lot of people do it, there's a Sky Mansion Fancy magazine, but not done for the vast majority. For a full civilization - thousands, millions of people - to move to the sky, I think there would have to be a damn good reason. ]
[Question] [ Note: this is not a duplicate of [Anatomically correct Giants](https://worldbuilding.stackexchange.com/questions/51771/anatomically-correct-giants) or [What would be the tallest possible height for humanlike creatures in earthlike conditions?](https://worldbuilding.stackexchange.com/questions/51686/what-would-be-the-tallest-possible-height-for-humanlike-creatures-in-earthlike-c) because my giants are far from humanoid. Anyway, the main question here is why they would evolve rather than how they would evolve. --- This question is one about my ongoing worldbuilding project about viable mythical creatures and how they fit into the modern ecosystem. The last three were: [Is petrifying vision plausible in an animal?](https://worldbuilding.stackexchange.com/questions/113648/is-petrifying-vision-plausible-in-an-animal), [Hydras as parasitic-mating, polyandrous amphibians?](https://worldbuilding.stackexchange.com/questions/114179/hydras-as-parasitic-mating-polyandrous-amphibians) and [Are wing-walking griffins viable?](https://worldbuilding.stackexchange.com/questions/114262/are-my-wing-walking-griffins-viable) The premise: This question will be about another important creature in the project, the giant. Most fantasy depictions of giants show them as massive humans, but I'd rather shake things up a bit. In my project, giants belong to the clade [Tethytheria](https://en.wikipedia.org/wiki/Tethytheria), with their closest relatives being the rhinoceros-like [Embrithopods](https://en.wikipedia.org/wiki/Embrithopoda). Here is a rough dendrogram of giant phylogeny I made (The taxon at the end of each lineage represents a Linnaean order): [![enter image description here](https://i.stack.imgur.com/lNJxq.png)](https://i.stack.imgur.com/lNJxq.png) The giants are the order shown in bold, Gigantoidea. Edit: I forgot to include the clade Tethytheria when annotating the dendrogram, it should be above the line that leads to elephants, manatees, embrithopods and giants. The problem: But why would very large quadrupedal browsers evolve bipedalism? The ancestors of my giants would have looked something like this, but not necessarily horned: [![enter image description here](https://i.stack.imgur.com/vKP6Y.jpg)](https://i.stack.imgur.com/vKP6Y.jpg) Image source: <https://alchetron.com/Embrithopoda> And now, they are bipedal and 10-18 metres tall. What evolutionary reason would cause this to happen? Why would heavy, quadrupedal herbivores end up as bipeds? The giants: At the moment, that question is a bit broad, so I'll give you some information about the giants I have in mind. Giants spend most of their adult life dormant, hibernating half-submerged in the earth. During this time, plants will often grow on their backs. The giants absorb nutrients from these and the surrounding soil to sustain them in their sleep. However, they require nutrient-rich soil to survive. Thus, they rise every 200 years to predate the [hydras](https://worldbuilding.stackexchange.com/questions/114179/hydras-as-parasitic-mating-polyandrous-amphibians) (Their mass births occur at the same time, and they emanate poisonous gases that, in large quantities, have a very negative effect on the soil's nutrient content). They also reproduce at this time, and baby giants spend about 20 years roaming and growing before their first 200-year hibernation. Their longevity is because of their size and inactive stages. --- So, with that information in mind, consider this: What would cause quadrupedal Embrithopods to take on a bipedal posture? I suggest reading up a bit on Embrithopod ecology, anatomy and physiology should you require further information. If you find this question broad, missing details or having errors, please let me know and I will amend the question as soon as possible. [Answer] Most of the answers currently focus on what the Rhino-giant might want or need that could cause selection favoring large bipeds, so I'll go the other way and focus on what they don't want. Your hydras are already a threat to the giants. I'm not sure if you've explained their poison yet, but it sounds like a great way to kill off some nearby giants for a quick calorie boost during mating season, either for energy to mate or to provide easy food for the young. The giants, when they were quadrupeds, were pretty helpless against the hydras. Charging isn't a great tactic against serpentine, multi-headed creatures. Hands, on the other hand (pun intended) are quite useful for grabbing those snaky necks. They also make it much easier to "un-dig" oneself after being awoken from hibernation by a hydra bite. Larger size makes for thicker skin, which means the first bite is a lot less likely to maim or kill. Side note - I know I said I was focusing on threats, but large size also means more surface area for absorbing nutrients, especially if they have long limbs and digits that can act like roots. I know your world is filled with other myth-inspired beasts, so I'm guessing there's probably at least 1 aerial predator to deal with, too. A bipedal strategy allows a lot more options for fighting off an attack from above, and large size makes the giants much harder to carry off. The adults would have been plenty large already, but perhaps the young were small enough to be carried away? As the species grew larger, even the young were too heavy to be taken. The thicker skin is helpful here, too, for surviving talons and bites. I have one more rather unconventional idea for explaining size. Camouflage. Usually, smaller is better for this, but the giants are using plant life to hide themselves while buried, and a conventional size doesn't allow much to grow, and certainly nothing large could grow without growing roots into or around the giant, killing or trapping it. If that doesn't happen, it's hidden by the moss, but that large area where nothing but moss is growing is a bit suspicious... Once large enough, though, the giant could have a very thick hide that is quite effective at holding roots, allowing bushes and small trees to grow, which hide it a lot better. When out of the ground, it may even be able to pass for a tree at a distance, if it's gathered enough growth and is thin enough. That's all I've got for now. I hope it helps! [Answer] Trees, in a world that goes from prairie to forest due to climatic changes the bipedal form becomes advantageous to herbivores of all sizes. Wide grasslands that shift through scrub and into climax closed canopy forest cover as the climate warms and rainfall increases over geological time. This would probably be because of continental drift rather than a post-glacial warming event, but either is technically possible. The grazers on those glasslands have to evolve new strategies to feed as the height of feed stock rises or they die out, the shifts are gradual but culminate in a bipedal giant cropping acorns right out of the tops of old growth oak forests in a similar way to Giraffes feeding on the top leaves of Acacias. [Answer] Well in nature a lot of excessive and often counter survival characteristics can emerge from sexual selection. A good example are birds, huge colorful feathers that makes you visible for all the predators are not exactly a good survival strategy, but when mating the most visible male birds have an edge over those who aren't that colourful. Because of this [sexual dimorphism](https://en.wikipedia.org/wiki/Sexual_dimorphism) in those species its usually very noticeable. In your story it could be that the female giants preferred those who could stand higher in a mating dance, eventually this lead to bipedalism in males and that trait got passed on to the females of the species. In that case the females would usually be a lot smaller than the males and a lot more agile. ]
[Question] [ I'm working on a humanoid vertebrate species that I'd like to be capable of true, flapping flight, but still have arms and legs completely separate from the wings. I also wish to avoid a "six-limbed vertebrate" scenario, since it has a number of fairly closely related species that only have four limbs. So, I've locked onto the idea of rib-supported skin membranes like the ones that lizards of the genus Draco use to glide. I know one question here already addressed the possibility of a similar set-up, but I'm working on the assumption of possibility and wanting to know what the changes required would look like. In particular, I want to know where the flight muscles for such wings would be located and whether, once flapping flight was evolved, a horizontal stabilizer like the Draco lizards' gular flag would still be necessary, but help visualizing any other prerequisite changes would also be appreciated. If it matters, the species in question is a sort of warm-blooded pseudo-mammal, and the range of motion for its spine is more mammalian than reptilian. [Answer] Lizards breathe using their intercostal muscles - the muscles between the ribs. This (in essence) moves the ribs back and forth, changing the body volume and producing inspiration and expiration. Linked is a movie showing slow motion fluoroscopy of a lizard breathing. <http://www.xromm.org/projects/varanus-breathing> [![fluoroscopic movie of lizard breathing](https://i.stack.imgur.com/vNKUk.jpg)](https://i.stack.imgur.com/vNKUk.jpg) It does not take much imagination to turn this motion into flapping. One could unmoor the muscles from the sternum anteriorly and use the two sets of intercostals to power the rib wings up and back. Or one might have an elastic connection to the sternum - the lizards power the wings up (dorsally) with the intercostals against this elastic resistance, and then get a powerful downstroke when the muscles relax and the elastic connection to the sternum pulls them back ventrally. Vice versa would work too - elastically drawn up then powered down. The linked site lays out the various motions of the ribs during breathing. They actually rotate some as well. It would be a good thing for a flapping flyer to rotate the wings on the upstroke to offer less resistance then rotate back for the downstroke to maximize resistance. I take away from the site that the intercostals are responsible for rotation as well. Lizards already have their intercostals doing double duty - both breathing and locomotion. I think this use would actually augment breathing while flapping - which seems to me a good idea giving the energy / oxygen demands of flapping flight. [Answer] First, that's not flight, that's gliding. Without some mechanism to generate lift, i.e. by flapping, flight by the use of rib extensions is basically impossible. They can be extended, but in Draco the wings are fixed. However, you can possibly develop some form of "false" ribs, by employing a novel joint above the ribcage, perhaps attached by cartilage and ligaments to lengthened neural spines. This would allow you to anchor "pull-up" muscles to the longer neural spines. To get around needing deep breastbones for the chest to anchor muscles to pull the wings down (take a look at a pigeon skeleton, their keels are huge relatively speaking), they could have anatomy that automatically forces the rib-wing, once extended to want to fold forwards (have the tips meet in front of the creature) so that the major force would be from the spinal process muscles pulling the wings back and open and anatomy pulling them closed. Sort of like a clap, where the effort is in you drawing your hands back, not in bringing them together. Also, unless the creature is very short-legged, I don't think you're going to have enough body length, even if you took the rib wings from behind the shoulders to the hip to give you an adequate wing to mass ratio for flight or gliding, a human torso is too short to fit a wing that can support the heavy head and legs, the legs make the whole thing too back-heavy. If you are okay with "rib\_like\_" structures, you might be better off attaching the extensions to be above the spine themselves. They can still use the neural spines to anchor muscle, but the down-stroke force would have to be generated by muscles pulling the ribs downwards. And you end up with a flier kind of like this: [![DnD Gold Dragon, art by Todd Lockwood](https://i.stack.imgur.com/3j9ip.gif)](https://i.stack.imgur.com/3j9ip.gif) Versus a regular six-limbed sort of flap (it's big so I didn't past it in). <https://i.stack.imgur.com/bumiN.jpg> But again, note how much length is given up to be a continuous wing to let rib-like projections work. I think this version is much more anatomically feasible than the first option, fitting the rib sails directly above the ribs to the sides of the spinal process. Though you might end up with a humanoid creature that is built very deep and broad of chest, with a buffalo hump. They would be humanoid but not humanlike in shape. The "buffalo hump" need not stand out. Buffalo have their hump because their neural spines are tall to support the weight of their heads. You can see the same with rhinos, which do not look particularly humpy, but have tall neural spines as well. ]
[Question] [ Assume the following situation: 1. A pre-modern culture A exists on continent/island X with no previous contact with culture B (the invaders). 2. Culture B discovers and invades X and the lands of A intend on conquering them. (This may be a centrally organized effort or one carried out by a series of adventurers.) 3. Infectious diseases are endemic in culture B (the invaders); members of culture A have not evolved/acquired immunity against those while members of culture B are less susceptible though not 100% immune. Members of culture B (the invaders) thus thus act as carriers that infect and decimate any population of culture A members encountered. 4. The resulting epidemics will decimate but not completely wipe out populations of culture A. Given sufficient time, immunity will be acquired but the population size will be severely decimated. Note on point 1: Culture A may be a stone age, bronze age, iron age, classic/imperial age, or middle age type civilization (the earlier the more interesting), but not industrial or modern. I.e., no steam engines, certainly no spaceships or computers, no railways, no electricity, no microscopes, etc. (Note that industrial or modern technology available to culture A would make the entire setting implausible.) The setting requires culture B (the invaders) to at least possess an advanced mode of transportation (say, ocean-going ships) that was before contact unknown to culture A. I would prefer culture B (the invaders) to be advanced compared to culture A. Should it turn out that the invasion is not survivable for culture A in such a case, an otherwise (besides transportation) similar technology level is acceptable. Clarifying edit: By survival of the culture, I mean maintaining a culturally distinct social/political/economic entity in the tradition of the pre-invasion society, though not necessarily the same government. Countries like India, China, Marocco, etc. are distinct entities in this sense, while surviving populations that are heavily integrated into the cultural entities in the tradition of the invaders (say, Native American reservations, or formerly nomadic tribes in Siberia) do not. Hypotheses: I assume that survival of A as an (independent) culture depends on: * The relative level of technology of culture B (the invaders) compared to culture A. * Whether the authorities of A are aware of the cause of the epidemics (presence of members of B combined with the lack of immunity in A). * The ability of culture A to prevent or deal with a general breakdown of political, social, and economic order that could be caused by severe decimation of the population as a result of epidemics. Question: * Is it conceivable for culture A to survive this onslaught as an independent culture? * Can the authorities of A implement measures that make survival (of the independent culture) more likely? Which measures would be expedient? * To what extent does the technology level and/or the difference in technology levels matter? * Are there possibly even historical examples? Some evidence: * We have several examples of invasions of this kind (Europeans in Hispaniola, Mexico, Peru, Australia, etc.). This is analyzed in, for instance, Jared Diamond's "Guns, Germs, and Steel" and in Yuval Harari's "Sapiens". In every case, the invaded culture perished as an independent culture, though small remnants of the population usually survived as subjects to the invaders (though in some cases the native population was completely exterminated as in Tasmania). In every such case, the native population had a technology level that was vastly inferior to the invaders. Probably they were also unaware of the role of the invaders in spreading epidemics. * We have many examples of cultures resisting invasions, even with technologically superior invaders (Ethiopia defending against the Italians, China limiting European influence and driving out Europeans from Taiwan in the 1600s, the destruction of three Roman legions by Germanic tribes in Teutoburg forest, etc.). To my knowledge, in none of these cases epidemics play a role. * There is interestingly one example of conquerors lacking immunity (i.e. the other way around): The Manchu Qing dynasty in the 1600s. They were more susceptible to smallpox than their Han Chinese subjects they had just conquered; they selected an emperor - Kangxi - on the basis that he had already survived a smallpox infection. Illustrative example: Consider the Spanish conquest of Aztec Mexico. Would it have been possible that the Aztecs defend successfully against this invasion (permanently, not just once)? All evidence (see above) suggests that this is implausible. Would it have been possible if they had been aware of the danger, causes, and mechanisms of epidemics? All evidence suggests that they (and all other examples) were not aware of it. Some evidence suggests that cultures that were aware of similar issues (the Manchu Qing dynasty) implemented successful policy measures - at least in a very limited scope. If not: Would they have been able to defend themselves with iron age technology? Or if the Spanish only had the technology level of, say, the classical Roman empire? Evidence seems to suggest that epidemics are the single most important factor. So it may even then not have been plausible. Related (but different) questions: * European conquest of the Americas without lack of immunity of Native Americans. Answers conclude that conquest and destruction of native cultures would have been less feasible, would have taken longer, and would have happened later if at all. [How would the history of American colonization by Europeans differ, if the Native Americans were immune to the new diseases?](https://worldbuilding.stackexchange.com/q/30616/47889) * Native Americans reaching Renaissance age without European interference: Some answers express doubt that this would have happened at all, others give estimates as low as 700 years. [How long would it take for the Americas to reach Renaissance-level technology?](https://worldbuilding.stackexchange.com/q/19469/47889) * Recovery of pre-modern society after collapse. Answers emphasize that this depends on many factors; one answer invokes the dark age in the early European middle ages and estimates 500 years on that basis. [How long would civilisation take to bounce back after an apocalypse?](https://worldbuilding.stackexchange.com/q/79803/47889) (This question is closed as too broad. I hope I narrowed the present question down enough with hypotheses, questions, and evidence, have I?) * Defending stone age civilization with some limited Renaissance technology and supplies (from crashed ships) against Renaissance era civilization invasion. Epidemics are not considered. Responses conclude mostly that successful defense is possible. [How do I defend an island nation from attackers with 15th century technology?](https://worldbuilding.stackexchange.com/q/29137/47889) [Answer] Unfortunately for Culture A, a large part of their survival is out of their hands, but they do have some ways to improve their odds. Just going through your hypotheses: Relative Technology: The biggest factor in the native culture's (lack of) ability to fight back against invaders. [This History StackExchange question](https://history.stackexchange.com/questions/11390/how-did-aztec-armor-and-weaponry-match-up-to-the-spaniards) shows just how badly the Aztecs were compared to the Spanish. The Aztecs had wooden clubs and chunks of obsidian, whereas the Spanish had metal; a lucky hit through Spanish armor could wound the Spanish soldier, a sword swing on any part of the body would maim or kill the Aztec soldier. This was fairly typical throughout much of the Americas, and even in Europe [the side with outdated technology and tactics often lost](https://en.wikipedia.org/wiki/Battle_of_Agincourt). If the native culture understood how under-powered they were, they may be able to win enough battles to prevent early settlement near them. For example, the Aztecs [scored an early victory](https://en.wikipedia.org/wiki/La_Noche_Triste) against the Spanish by overwhelming them in the cramped streets of Tenochtitlan. The native culture would have to use their vastly superior numbers and knowledge of the local terrain to have any hope of repelling attacks by a technologically superior invader. If they win enough battles and they can scavenge enough weaponry and/or take enough knowledgeable and semi-willing prisoners, then they can start developing something that comes close to matching the invaders' level. They wouldn't have nearly the industrial scale to maintain it, but they may be able to [do enough damage](https://en.wikipedia.org/wiki/Comanche_Wars) to survive. It helps if Culture A happens to be inhabiting land that the invaders [don't really want](https://en.wikipedia.org/wiki/Sentinelese) and thus not worth the effort. If they are on valuable land, [well...](https://en.wikipedia.org/wiki/Trail_of_Tears) Epidemics: By far the largest cause of death among native cultures were the diseases brought by invaders. Culture A really has only two hopes here: that they are immune to some native disease that will harm the invaders, or that they were already knowledgeable on early forms of vaccination. They have no control over if the invaders get wiped out by disease, so if they have/develop and understanding of disease and inoculation they may be able to get through the epidemics relatively unscathed. The first published instance of Smallpox inoculation was in [mid-1500's China](https://en.wikipedia.org/wiki/Smallpox_vaccine), before much of the world-wide colonization efforts. The inoculation is [as simple as blowing Smallpox infected tissue up your nose](https://en.wikipedia.org/wiki/Variolation#Origins_of_variolation) to give a minor Smallpox infection, so no technology is required. Although this still gives a ~1% mortality rate, it is much, much better than Smallpox's normal 20-30% mortality rate. So, if Culture A happens to already have a history of inoculating against diseases and/or happens to have a lucky experiment in the early days of infection, they should be spared the worst of the epidemics and population loss. Even lacking this, policies such as strict quarantine of infected individuals combined with essentially an immunity-based breeding program using the survivors to quickly immunize the population will definitely help them survive the epidemics better than in real life. Societal Breakdown: No real way to survive this, unfortunately. If the native culture is beaten, sick, and depleted enough for their politics, economy, and overall society to collapse, then I doubt they would be able to recover enough to defend against whatever caused this breakdown. If Culture A reaches this point, then they're no different than any of your examples of lost cultures. In summary, a culture may be able to survive if they're lucky. If they understand that they're only military advantage is numbers, they may be able to beat the invaders early on. If they can quickly adapt to use invaders' technology and aren't on valuable land, then they may be able to show the invaders they aren't worth conquering. If the happen to have good knowledge of inoculation, quarantine, and immunization, then they may be able to avoid devastating epidemics. There's definitely a lot of luck necessary to the culture's survival. Closer technology levels and less-deadly diseases will certainly help the natives beat back the invaders, though the chances still aren't good. The [Maghreb region](https://en.wikipedia.org/wiki/Maghreb) is a good example of repeated attempts of conquest leading only to integration of the invader's culture into the native cultures rather than outright destruction, and there are plenty examples of different native cultures still existing there with little change. However, if it was likely that a native culture could survive a superior invader, then there would be many more real-life examples of that happening. [Answer] Well researched question. The immediate answer I have may prevent the epidemic, so i need to preface with a potential scenario. In one manner or another, this native population needs to understand the risk these invaders pose (earlier the better) so they may begin resisting. Not resisting early is a major downfall here. On the same note, you need some degree of trade to successfully spread the epidemic (exposure to a person with small pox isn't a definite spread of the small pox virus, trading with this person for lets say a blanket and then using the exposed blanket is a much more likely infection). This means immediate resistance might halt the spread of an epidemic and somewhat negate the question. That being said, the scenario that happened on Earth with a slight tweak should still work...colonists to North America came upwards of over 100 years after the initial contact happened (and the initial spread of disease) and the native populations were already decimated by the time European colonists actually arrived. Lets say we have a scenario where the initial contact happened and the epidemic broke out, however the natives learned this was due to contact with Europeans and by the time the colonists arrived, the natives were already prepared to resist. When colonists arrived in the New World, they were not well prepared or suited to life on the new continent. Foods were different and climate was significantly harsher than what they were used to. The journey was long and as such, supplies from the new world (food) could not be relied upon for long. As such, the new colonists were dependent on trade with native tribes for provisions for their early colony. The longest running tradition from these early colonization times is Thanksgiving, celebrating the natives sharing of their harvest with the new colonists. It should also be known that in these early colonist days, the native populations still had the military might to directly confront and destroy most of these settlements with ease, if the will was there and they were unified with their actions. But lets say for the purpose of the question that the colonists were capable of bringing enough firepower over with them that they would win a conventional engagement. Whats left when faced with an overwhelming conventional force? Guerrilla warfare of course. The best method of defense for the native population is to make life on these new colonists as difficult as possible and to prevent (or at least limit) their ability to gather resources from their new homeland. These tactics are destructive and would not be turned to unless the native population knew of the grave threat to their own existence...ultimately it's a version of scorched earth tactics as they are going to purposefully destroy the resources a new colony needs. * burn the forests around them and prevent their easy access to building materials and fuel * They will need farms for food...burn / destroy their crops at night and slaughter their livestock (extra points if they can show wolves how to get at the easy prey). * Reduce their ability to resupply from the sea (sneak in under the cover of darkness and use arrows to set their port ablaze. sneak in under the cover of darkness at low tide and cut the supports for the piers...creativity here goes a long ways). * Burn hay supplies so they cannot keep horses. * When winter strikes, sneak in under the cover of snow and burn barns so their livestock won't survive the winter. * Locate the source of their water supplies and 'pollute' them or divert the water flows. * Dam a nearby river and backup the water of a river until it spills its banks...break your dam and let wave a of water hit the new colony. repeat. * allow no economic activity. New colonies were capable of funding themselves by bringing new goods back to the old world to sell...don't trade with them and don't give them the economic reason to be there. Ultimately, this native peoples (pretty much independent of tech level) need to make it extremely tough for the new colonists to survive and harshly impact the economic feasibility of these colonies. [Answer] Preserve There are places where natives are allowed to live unmolested and conduct their own affairs. The Sentinelese are one such group. As opposed to Amerinds who were thoroughly conquered before being relegated to their reservations, the Sentinelese were so hostile and their island so unpromising that they have been left alone. <https://en.wikipedia.org/wiki/Sentinelese> > > The Sentinelese (also called the Sentineli or North Sentinel > Islanders) are the indigenous people of North Sentinel Island in the > Andaman Islands of India. One of the Andamanese people, they resist > contact with the outside world. They are among the last people to > remain virtually untouched and uncontacted by modern civilisation. > Their island is legally a part of, and administered by, the Indian > Union Territory of Andaman and Nicobar Islands. In practice, however, > the Sentinelese exercise complete sovereignty over their affairs and > the involvement of the Indian authorities is restricted to occasional > monitoring, ever more infrequent and brief visits, and generally > discouraging any access or approaches to the island. The possibility > of future contact, whether violent or non-violent (armed or unarmed) > has been discussed by various organisations and nations. > > > In your world, your civilization of primitives is thoroughly conquered, almost. Holdouts of the conquered people in one isolated area are not conquered partly because of their ferocity but more because of a general lack of interest by the conquerors in that region. Their civilization and culture of the otherwised vanished / assimilated people persists in that refuge. The conquerors decide to leave them alone indefinitely (as the Indian government does the Sentinelese) and enforce that condition - maybe out of some sense of fairness, or cultural presentation, or artistic merit or what have you. [Answer] If they don't have resources worth taking, or if their valuable resources are cleaned out then they can survive culturally. Polynesians are an example. New Zealand and Hawaii having resources worth keeping were colonised and basically taken over. Culture there is now mainly lip service. Tonga is a kingdom on the other hand, and like many other Polynesian cultures has nothing worth taking any more and therefore is independent. Samoa, and numerous smaller ones as well and many Micronesian countries. Politically though they tend to be pseudo-democracies, but for the peasants in the outlying regions life is much the same. [Answer] Almost every other aspect has been dealt with nicely in other answers, so I'll focus on another aspect of disease. Sub-Saharan Africa was colonized relatively late due to disease, especially [sleeping sickness](http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002772). That disease along with malaria, and a similar disease to sleeping sickness that attacked animals struck the Europeans low, and kept them largely out of the area until they bred horses that could survive and found ways to treat the worst symptoms of the various diseases. With similar illnesses on Continent X, it would give Culture A a chance to recover from the epidemics that invariably cut through the population. However that isn't enough to save the culture as an independent state. So having Culture B, able to live relatively healthily on part of the coast where the disease is uncommon would be useful. With towns from Culture B set up close by, while the natives have most of the continent full of diseases they can survive, will give them a chance to gain the new technology, learn how to fight and deal with the newcomers, and rebuild their strength. By the time Culture B has worked up immunity or medicine to allow them to expand, Culture A will have done the same and will be able to fight back more effectively. ]
[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. Assume an Earth-like or super-Earth terrestrial planet in a state comparable to [Precambrian](https://en.wikipedia.org/wiki/Precambrian#Planetary_environment_and_the_oxygen_catastrophe) or [Archaen](https://en.wikipedia.org/wiki/Archean#Palaeoenvironment) Earth. The atmosphere is mainly nitrogen and carbon dioxide, perhaps some methane, but very little to no free oxygen. [CHON(PS)](https://en.wikipedia.org/wiki/CHON) life has evolved and struggled, but that's about to change: something has evolved to make use of all that CO$\_2$. With a twist. What biological process(es) would explain why these upstarts take atmospheric CO$\_2$ and retain the oxygen rather than release it to the atmosphere? To be clear, I'm proposing the [Great Oxygenation Event](https://en.wikipedia.org/wiki/Great_Oxygenation_Event) be inverted, with a net loss of oxygen as it somehow is incorporated into organisms and then, over geologic time, [sequestered](https://en.wikipedia.org/wiki/Carbon_sink) as carbon was on Earth. * Presumably there needs to be some evolutionary advantage to keeping the oxygen rather than pumping it out as a waste product, but I'm not sure what that would be. * The solution needn't be an alternative to photosynthesis as we know it, it just can't result in oxygen waste. A case might be made for carbon monoxide or other oxidized waste, with the organism retaining a single oxygen molecule from the reaction, as long as the effect is cumulative. * I have not specified that this planet has water oceans – if an alternative such as ammonia helps, then assume that is true even if unlikely. * Similarly, if adjusting the crust, atmosphere (other than the composition mentioned), temperature, or parent star in some way helps, assume it. * If this results in a [Medea situation](https://en.wikipedia.org/wiki/Medea_hypothesis), turning the planet hostile to the organism(s) consuming the carbon dioxide and resulting in their extinction, so be it – as long as all that oxygen ends up locked away. --- This is my first [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") question, so if I've contradicted myself or overlooked something that makes answering impossible, point it out. [This question](https://worldbuilding.stackexchange.com/questions/34811/how-would-the-great-atmospheric-catastrophe-come-about) appears to be related, but is not a duplicate. [Answer] ## Clearly, your planet has iron to burn! The best analog for something that might happen is something that has already happened. The early Earth itself was covered in iron- Fe (II), to be precise. This caused a huge delay in the oxygen level increase. For about a billion years post-photosynthesis evolution, oxygen levels stayed low because the free oxygen being produced was essentially rusting the crust of the Earth. This is the source of the beautiful [banded iron formations](http://jersey.uoregon.edu/~mstrick/RogueComCollege/RCC_Lectures/Banded_Iron.html) from the Precambrian Era. However, this was a [waste of energy](https://www.frontiersin.org/articles/10.3389/fmicb.2012.00096/full). The reaction of oxygen and iron actually produces energy and some bacteria have developed a way to capitalize on that. Meet [Acidithiobacillus ferrooxidans](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC357980/?page=1). It's a bacteria found on Earth in acidic environments that survives by oxidizing iron for energy, and is found in iron mines and in your car's tailpipe. It's an [obligate chemoautotroph](http://jb.asm.org/content/77/5/642.long) and thus gets all of its energy from this reaction, [producing NADH](https://www.frontiersin.org/articles/10.3389/fmicb.2012.00096/full) from the electron gradient. From the [Silverman & Lundgren paper in 1958](http://jb.asm.org/content/77/5/642.long): > > [...] the energy derived from the oxidation of ferrous iron could serve as the sole support for the growth of a CO$\_2$-assimilating microorganism > > > Sound familiar? I think it sounds a lot like what you're looking for to corrupt your Earth. This figure shows the chemistry involved- note that the O$\_2$ is being taken up along with ferrous iron to produce energy (ATP & NADH) and water: [![The chemistry behind rust bacteria](https://i.stack.imgur.com/FsdwJm.jpg)](https://i.stack.imgur.com/FsdwJm.jpg) ### Some caveats This chemistry only works under very acidic conditions. Fortunately, the early oceans were already quite acidic and with an atmosphere that's mainly CO$\_2$ that'll get pushed even lower. Additionally, these bacteria are able to create their own pockets of acidic pH- one experiment saw them get [as low as 0.5](http://jb.asm.org/content/77/5/642.long) units in culture. That's terrifying. Also, I'm not sure how well this would actually sequester the oxygen. Assuming deep sea export, the iron oxide can be stashed for billions of years, but at a relatively slow rate. ### Other options If you don't like Acidithiobacillus ferrooxidans, there are two others that may be worth considering. [Mariprofundus ferrooxydans](https://en.wikipedia.org/wiki/Mariprofundus_ferrooxydans) is a common microbe at deep-sea vents, but operates at a neutral pH and doubles quite readily. It's so weird that it's currently in its own class (the [Zetaproteobacteria](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1930151/)) within the Proteobacteria phylum. The other option is the essentially magical [Rhodopseudomonas palustris](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1183355/), which is both phototrophic and Fe(II) oxidizing. It also functions at near-neutral pH and is a decent candidate for an early life form in the Archaean oceans. There are [others](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC202013/) that do similar things, but R. palustris is my personal favorite. [Answer] The simplest answer to this is that the plants that conduct photosynthesis to generate O2 and Carbohydrates for their own use only generate sufficient quantities for their own [metabolic processes](https://en.wikipedia.org/wiki/Metabolism). Plants use O2 and CHO compounds just like animals do, for exothermic reactions that release energy they can use. [Photosynthesis](https://en.wikipedia.org/wiki/Photosynthesis) is an endothermic reaction designed to use energy (in the case of plants, sunlight) to reverse this reaction on grounds that there is no available O2 and CHO compounds for them to consume. On Earth, the plants just keep releasing this extra O2 as a 'waste' gas, because storing it for future use is corrosive and serves no purpose given that the plant can produce more than is needed at any given time. If the Earth was further away from the sun, say on the edge of the habitable zone, AND there was a metabolic regulation system built into the plants so that when they had sufficient O2 and CHO Compounds they could suspend their photosynthetic processes (perhaps storing small amounts of O2 for night time and the like) then the great oxygenation event essentially wouldn't have happened. There may be some loose O2 in the air (released perhaps by a dying plant when it's short term store is exposed to the atmosphere) but generally speaking, plants would have only produced what they needed. This in turn would of course mean that your planet could only possibly support plant life; no animals. ]
[Question] [ There's a empire with big jungles (60% is covered by jungle). Actually, I wanted the empire to use a lot of heavy infantry and cavalry. After doing some research, however, this seems to have hardly been the case with cultures that lived in jungles where light soldiers were dominant. Is it possible to justify heavily armored soldiers or should I remove it? [Answer] It could still work if the empire is burning down (or cutting) the jungle to make space for itself. That is: there was 100% jungle before the empire rose, and by the time of your story there is only 60% jungle and decreasing. It is very reasonable that the empire would be reducing the jungle if most of its activities, including most of its armed forces, do not fit well with the jungle. [Answer] # Europe was covered with forests I don't understand why you think the jungle will be an impediment? Northern Europe's natural vegetation would be forest of oak and beech and hornbeam as far as the Elbe, then oak and pine to Poland and beyond. That is to say, it was closed canopy forest as far as the eye could see. Of course, then man came. The forets were cut for timber and to clear for agriculture or maintained as pasture for grazing. The heavily modified landscape was then suitable for heavy infantry and cavalry formations. If your jungle civilization is heavily populated, then it too will be managed for man. There will be paddies for growing rice or taro, dryland fields for cassava, and plantations for oil palm, coconut, or cocoa. They may even keep flood plains open to graze their water buffalo or capybaras or tapirs or whatever exotic creatures they have have domesticated. In short, man will make the environment he needs. Heavy cavalry won't go into the dense forests, just as it avoided the Ardennes and Black Forest and other dense forests of Medieval Europe. But if man makes the space, it will operate just fine. [Answer] Heavy infantry and cavalry need cleared and relatively level space to operate. This was well known in antiquity (read about how Hoplites moved and fought, for example) and even into the modern period. The "French and Indian War" (the North American part of the Seven Years War) largely revolved around light infantry units such as [Roger's Rangers](https://infogalactic.com/info/Rogers%27_Rangers) being able to move and fight in the uncleared forested wilderness, and their French opponents were doing the same by coopting Native tribesmen as fighters for their side. Conventional infantry and cavalry could operate in the settled areas, as they were generally cleared to a great enough extent that they operate. In Europe, light such as British Rifle regiments or Prussian Jaeger (hunters) were also added to the orders of battle to deal with broken or complex terrain where conventional units were at a disadvantage. Even today, mechanized units operate in open terrain while light units (such as the US Ranger Regiment) specialize in operating in complex terrain such as jungles, forests or urban environments. The distinction is nowhere near as clear as in earlier times, since any unit can be connected to a great deal of firepower and logistical support these days, using radios, helicopters and persistent air and firepower, and of course even man portable weapons have the sort of firepower artillery could bring decades ago. [Answer] Heavy infantry and cavalry (and artillery, etc) are a function of many factors: * Terrain * Availability of weapons and horses * Capabilities of the opponent * Wealth available to pay for the forces You can certainly march a column of cavalry and heavy infantry through a jungle and across rivers. All armies can do that. But it's a wise action only if that's the appropriate force to win the fight at the end of the march. Other answers have already talked about Terrain and Availability of weapons and horses. The capabilities of the opponent are obviously important. An enemy lacking anti-horse technologies will be (literally) overrun by your cavalry. Conversely, an enemy with a walled city and complex defenses requires your force to be much more sophisticated, and to include artillery and engineers...and perhaps allies. Even small expeditionary forces require great wealth to gather, equip, and sustain. Those soldiers won't train and pay themselves, their weapons and armor don't grow on trees, trained warhorses don't pop out of every paddock, food doesn't grow along the line of march in the quantities you need, etc. The promise of looting won't keep good soldiers for very long. European conquerors brought all the firepower they could afford. If they could have afforded more, they would have brought it. ]
[Question] [ Here is the scenario: Two factions, one defending its planet, the other attacking it. The winning condition for attackers is capture of leadership, so boot on the ground are required. The planet is Earth-like, the capital metropolis is coastal. WMDs on the surface are off the table. Defenders have a wide range of equipment at their disposal, from surface-to-orbit missiles, to spaceships, satellites, planes, VTOLs, airships, choppers, tanks, boats and submarines. Attackers are capable to launch and recover planes from orbit. They can launch troop transports from orbit as well. They have no lack of orbit-to-surface artillery either. They can match defenders in space, in the air and on the ground, but not really on the sea. Attackers can rain death from above on anything on the surface, that includes boats. While boats can be used as a platform to launch aircrafts, troops and artillery strikes, those capabilities are redundant. Bringing in boats from space is somewhat of a logistical problem. On the other hand, opening another front could have its advantages to divide defenders' attention. Launching planes/troops from the sea surface might also be less risky. It would be a new tactic, so there is the element of surprise to consider. The first question would be: Is it even worth taking the fight to the sea? Now, assuming we want to fight aquatically, attackers have developed a new type of vehicle, dubbed Space/Naval Hybrid Assault Platform (military loves acronyms). It is a space-worthy ship specifically designed for the task of landing on water and floating thereafter. It cannot takeoff without assistance, and cannot fly in atmosphere beyond controlling its descent. It could conceivably be single-use, e.g. you could disassemble it for building materials for a base of operations on land, or you could just beach it for similar results, or it may just be a fancier carrier/assault boat. So the other question would be: What are benefits and drawbacks of such ships, and what would they best be used for? [Answer] ## Sea warfare is kind of deprecated already. The only real reason major global powers still have a navy is because, compared to a ship, planes need to refuel and re-arm often. If you have very fast space-borne/airborne vehicles, that don't need to re-arm (energy weapons) or can do so quickly (high-speed propulsion) and need to re-fuel only once in a while (fusion-reactor), what use could a ship be? Such a vehicle would be way superior to any seaborne vehicle. You can see such a trend already, all major powers have/want aircraft carriers, and their only weakness is being a ship (vulnerable to submarines). BTW, why do you even have planes when you have space-ships (no atmospheric-flight capable engine?)? Considering the advanced technology level, I think it's unreasonable to think that your attacking force shouldn't be able to field a constant military presence going from orbit to sea-level above the defender's capital city. All this without ships. Even today, planes very rarely engage in dogfights. Using missiles, engagements are performed at many miles distance. Why shouldn't your orbital artillery, space ships & orbital-deployed planes be enough to suppress any naval fleet? You don't need a ship to destroy a ship, you just need a weapon that can reach it. It isn't that easy for a ship to hide, since the sea itself doesn't provide cover from sensor detection, more so if the sensor scans from orbit. There already are [anti-ship missiles systems with ranges of almost 1000Km](https://en.wikipedia.org/wiki/Anti-ship_missile), space is just a few hundred Km away. Why would you deploy ships when you just can launch swarms of missiles from orbit to kill any seaborne vehicle? You could even just drop space debris or some [metal pole from orbit](https://en.wikipedia.org/wiki/Kinetic_bombardment) onto the ship, ships are slow, and the impact of such an object near the ship would have the same effect of a nuke. [Answer] It might be worthwhile from a couple of perspectives. The advantage you are looking to secure is a speed advantage. Launch an attack from 3 miles out and your defenders will have a lot less time to respond. Attack from orbit, there is actually more distance to cover, more time to prepare, and so on. Outside of lasers in space, projectiles of any sort have travel time, and that time can be used to defend. Hyperspeed type projectiles are too devastating to be used willy nilly around population centers according to your rules. You can use your SNHAP to get to the surface in areas where the defenses are thinner. Have lots of troops and armaments on board. Don't land on the surface, go underneath. You will be harder (but not impossible) to detect. Land your boats all over the oceans, and have most of them go dark and move around a lot. Have one hit a coastal target on one side of the planet, hit another on the other side. Keep up some distracting stuff for a little while. Mass the troop carriers and logistics boats for an amphibious landing assault on the capital city. use last second concentrated aerial attacks to get the defenders looking up. End the aerial bombardment with mass fire on the coastal defenses, then start the ground assault. Why do this? You could gain a pretty good logistical advantage. You could get your troops to the surface in relative safety and move them to where they are needed, along with the support equipment and so on. If you lose a supply boat, no problem, send another because the main assault is a while away. You get to use the SNHAP to distract the defenders and even demoralize them. There are psychological boundaries your defenders will have and you are breaking those too. The defenders need those oceans, and so will hesitate to take drastic measures. Think about how hard it can be to work yourself up to go see a doctor to have some sort of surgery. It's your body, it will hurt, even though the whole thing will be ultimately beneficial, you still don't want to do it. That will translate to "If I destroy these U-boats, it will cause a lot of damage to the coastal ecosystem" Time runs out while they try to both protect the coastal ecosystem and find ways to destroy the boats. I don't necessarily think that these SNHAP's will be a total game changer, but it's not a useless idea by any means. [Answer] I assume that the leadership that needs be captured resides in the coastal metropolis. The attackers are practically 'laying siege' to the capital, with the objective of breaking through the defensive perimeter and occupying it, capturing the government and making them capitulate to their terms. Initially, I would go with a Special Forces operation to achieve that objective, instead of planet-wide warfare. But that defies the assumptions of the problem. The sea, for this coastal metropolis is (a) avenue of resupply/logistics support and (b) open escape route. For both (a) and (b), the attacker (whether they like it or not) will have to take the fight to the sea. To achieve the above objective, as it seems that the capabilities are more or less balanced, the invaders would have to control the naval theatre of operations. However, considering their space position and advantage, I would say that it would not be worth it to build naval capabilities. Instead, invest the same resources into obtaining space and air superiority. This will achieve the same result even over the seas - the defender's navy will be slaughtered without air support. So, to the second question, my answer is: such ships would not be cost-effective considering their capabilities. Any capability they have (troop carrier, air carrier, etc) and, most importantly, the effect of carrying out the capability (troops on the ground, air superiority, etc) can be achieved by other means, with existing capacities in greater number. [Answer] Ships would be obsolete. Boats can't adequately protect themselves from orbital bombardment, and same goes for cities. If you want to overcome this problem, introduce the concept of "shields", so, like in "Empire Strikes Back", an attack can not be launched directly from space, but rather via ground (or sea) based force fighting close combat. Without meaningful protection (like from using shields), losing orbital superiority would be an endgame for the defenders. They can still burrow underground and launch counterattacks, but from that point on they will be the mice in cat and mouse game. What if an attacker can't establish orbital superiority? Then defenders can stand for quite a long time, although attacks on them would be exhausting, like German air raids on London during WWII. For attackers, it would not be practical to bring the fight into the sea, because this is where they are the weakest. It would make much more strategic sense to try to establish a foothold on defender's planet using their strongest assets. ]
[Question] [ Premise In the near future, a cult-like ruling family worships symmetry and condemns asymmetry. By association, they are condemning much of nature as there are many instances of asymmetry in nature (crooked trees, irregular shapes of clouds, ect). To further "defy" asymmetry and nature they take control of a modern industrialized nation and arrange their royal marriages based on consanguinity from the beginning of their reign and for many subsequent generations. This time period may well span hundreds of years. I was pleasantly surprised to find a similar post here: [How to negate the effects of long-term close relative inbreeding in a ruling dynasty?](https://worldbuilding.stackexchange.com/questions/56198/how-to-negate-the-effects-of-long-term-close-relative-inbreeding-in-a-ruling-dyn) Though the time seemed to be more of an ancient setting, it was a helpful analog. Yet, it should be noted that my core question of genetic engineering's potential role in this matter remains unresolved. Problem If natural selection were to run its course, then over time the long run propensity of the ruling family's heirs that did not have any harmful traits will approach zero. This is due to inbreeding having the effect of increasing the relative proportion of homozygotes to heterozygotes. I'm not familiar with bio-statistics, so I'm not sure if this happens at a geometric rate or an exponential rate. Technical details aside, since the ruling family will be ruling indefinitely or at least for centuries, inbreeding will most likely create many genetic "weak-links". Attempted Solution By utilizing present or near-future genetic engineering, the ruling family wishes to counteract the harm that may result from inbreeding from things such as having two recessive alleles. I have two specific implementations in mind: 1. The ruling family first "perfects" their genomes (becoming immune to all diseases/cancers/deformations) before inbreeding and hope that no matter which combination of traits are inherited, the offspring will be strong. 2. Micro-manage each conception and "pre-ordain" the desired trait combinations. (Presumably more involved than choosing eye color?) And assuming no outside DNA is ever introduced. Question In the present day/near future, if all moral limitations were lifted, how feasible would the above solutions be? How robust could we expect this kind of solution to be; would there be inherent random mutations that no amount of genetic engineering could address? If the consensus is one or both are not realistic, then what needs to happen in terms of technology to facilitate the goal of prolonged inbreeding? Further Clarification * other genetic engineering solutions are welcome * Goal: A solutions that strikes a good balance between being realistic and awe/fear-inspiring * Budget: Unlimited * Era: present, near future * Moral restrictions: little to none * Duration: ideally indefinitely (as the title suggests), or at least 500 years * Inbreeding type: immediate relatives (seen as more "symmetric") [Answer] Yes, "genetic engineering" can solve the problem. First and most simply, you could just flip a coin and clone either the mother or the father (or make the gender their choice), thus zero mutations from the parent stock. Second and more complex, the problem is mutation due to miscopying of a genome, or a poor choice of inheritance. With genetic engineering (even today) we can specify every letter of the genome and simply manufacture it that way. For your purposes, an inventory of the genes of the ruling family can act as a library of allowable alleles (variants of a given gene) and gene segments, and a random (or intentional) selection of each part, given the founding library, could be the only allowable "persons" to be born. In the event such a person turns out to have an undesirable trait due to some untested combination of allowable genes, Their combinations can be flagged as suspect, or if a combo appears multiple times as suspect, flagged as prohibited in the library. [Answer] The way to do this most efficiently is to bank sperm from the Most Excellent Ruler, and arrange that he be the father for serial generations, each with his own daughter / granddaughter. Consider that 1st generation daughters are 50% most excellent, 2cond generation 75%, 3d is 87.5% and by 6th generation you are 98.44% Most Excellent Ruler genes. Of course a little scrambling might happen by meiosis etc but there will not be truly new genetic material introduced. These 6th generation descendants are like an inbred strain of lab mice, free of genetic disease and they may now breed freely with each other. Mutational events remain possible, of course and it might be safest to stick to the frozen sperm of the Most Excellent Ruler, thus reducing the chance for mutation by half. Do not worry about running out of banked sperm - he froze away an enormous amount. A benefit from this method is that there can be many 1st generation daughters (of different mothers) and so the project can be done in parallel with many generations growing up at the same time. If the original mother has a disease causing recessive gene it will not be important because there is no chance for brother-sister matches and it will be diluted out along with her DNA. In the (extremely unlikely!) event that the Most Excellent Ruler has a disease-causing recessive gene, the progeny carrying double recessives will become evident along the way. The dangerous gene will be identified and double recessives culled. Once you know that dangerous gene is present in the banked sperm one could correct it with genetic engineering by inserting the non-disease dominant copy of that gene from the Most Excellent Ruler. But the gene would persist in the banked sperm. Better and cheaper would be sorting out and disposing of sperm that carry that recessive gene. I am not confident one can nondestructively identify various genes in sperm. Once the recessive genes of interest were known it might be necessary to grow embryos in vitro until a cell could be samples without destroying the embryo, to certify that dangerous genes were not present. In the unfortunate instance that the Ruler carried multiple recessive genes this would be cumbersome and would need to be done with each successive generation to avoid reintroducing those genes from the banked sperm. If that were the case (multiple recessives in the sperm) once one achieved near purity in the 6th or subsequent generation, one could allow a male to reach adulthood and be the new sperm donor for all subsequent generations. His genome (and sperm) would represent the genome of the Ruler purged of recessive genes. [Answer] The simplest and most effective genetic engineering solution is a technology widely used today called [Preimplantation Genetic Diagnosis](https://en.wikipedia.org/wiki/Preimplantation_genetic_diagnosis). The concept is relatively simple and has been around for decades now. You take eggs and sperm from the future mother and father and perform in-vitro fertilization to produce many embryos. You allow the embryos to divide a few times to produce more cells and then you extract a cell from each embryo. You take the DNA of this one cell and analyze it to determine the genetics of the rest of the embryo and the potential child that it will produce. Now you can simply choose to implant the embryo whose genetics you like the most. A side effect of this procedure is you can also determine the sex and potentially other non-health related phenotypic traits of the child. PGD isn't widely used for a few reasons, but I think it would be a perfect fit for your ruling dynasty. First, it's only particularly useful for couples with a high-risk of passing on hereditary diseases. Second, it’s quite expensive. Third, many people have ethical concerns with discarding many fertilized embryos. It perhaps isn’t the most fanciful genetic engineerign technology, but it’s certainly the most realistic for a near future scenario. ]
[Question] [ Say we're on a ship traveling between the Milky Way and Andromeda. We decide to stop and take a look out our space-windows. What do we see? I'm presuming that the Milky Way and Andromeda would both be large and easily visible. But what about the other galaxies, further away? Would stuff normally restricted to, say, the Hubble Deep Field be visible to the naked eye, or would we end up seeing a lot of blackness? [Answer] The [Hubble Deep Feild](https://en.wikipedia.org/wiki/Hubble_Deep_Field) is not a picture in the normal sense, it was a very long exposure ~140 hours total. In intergalactic space, you would probably see only a night sky that was mostly dark with hazy "stars" or patches that are actually galaxies. Possibly the shine of a supernova. [Answer] Allow me to introduce you to the [Cosmological Principle](https://en.wikipedia.org/wiki/Cosmological_principle). According to this, the universe looks the same everywhere, from wherever one stands, and in whatever direction one looks. After all, our planet Earth is in some ways nothing but a big space ship with one really big all-around window. Because we are inside a galaxy, we usually see that as a small dense area in one area of the sky, which we call the milky way. Out there, the view will be virtually the same. There may be a small area more densely populated with stars in the direction of the nearest galaxies, but that is the only clue we will have. [Answer] I think that by the time you get halfway between the Milky way and Andromeda too look out the window, you would be in the middle of a galactic collision. Even at FTL speeds it would take tens of thousands or even possibly millions of years to reach our nearest neighbor Andromeda. It is a nice thought that we could one day reach that far, but it would take an extraordinary technology and energy source to even think about a journey of that magnitude. ]
[Question] [ If two incredibly strong incredibly indestructible characters were fighting on earth could one punch the other one into space? By space I am assuming that we at sea level and are trying to escape the earth's gravity well to guarantee the victim does not return to the planet. We are assuming that strength is infinite and are completely indestructible, but there are some considerations. I would like to have a habitable planet left afterwards. Overall it would be good to know how much collateral damage this could cause. Let's assume the character cannot magically brace themselves against a point in space like Superman, and there would be an equal and opposite reaction, that may also cause collateral damage. Besides the superpowers these characters have weight and shape similar to normal humans. We can also assume they are perfectly rigid objects and that the punch is perfectly elastic if this makes life easier. Also if punching is too destructive, could a throw that gives a little more time for acceleration reduce the damage caused to the surroundings? EDIT: I cannot consider accepting the current answer the escape velocity at 12km above sea level where the atmosphere ends is still over 11000 m/s An object traveling those 12 km from sea level at 11,000 m/s would be down to under 200 m/s due to air resistance after a quick calculation here <http://www.jayandwanda.com/tt/ballspeed_calc1.html> . This means the answer does not remotely consider putting in enough energy [Answer] On Earth, [escape velocity](https://en.wikipedia.org/wiki/Escape_velocity) is about 11 km/s, or 11,000 m/s. Assuming the opponent weighs around 70 kg (maybe more), that's a kinetic energy of at least $$\text{KE}=\frac{1}{2}mv^2=\frac{1}{2}\cdot70\cdot(11000)^2=4.235\times10^9\text{ Joules}$$ Furthermore, the opponent would have a momentum of $$p=mv=(70)\cdot11000=770000\text{ N s}$$ Even if the punch is given in one second, that's still a force applied of 770,000 Newtons. For comparison, the force of a 70 kg human on Earth is about 700 Newtons. This person would be subjected to a force (and thus an acceleration) 1000 times that. They will be crushed like a soft peanut. So no, they will not reach space today. Furthermore, the punch would impart the same amount of momentum to the puncher, meaning that they would be subjected to the same amount of force. . . . but you've stated that they are both indestructible. So neither one will be crushed like a soft peanut. So, let's assume that the puncher does in fact deliver a force of 770,000 Newtons to the opponent. A force should then act on the puncher, of the same magnitude and opposite direction. Let's look at a diagram here. Assume the opponent is launched at an angle $\theta$ from the ground: [![enter image description here](https://i.stack.imgur.com/lnO2d.png)](https://i.stack.imgur.com/lnO2d.png) The force on him is $F$, and so the force on the puncher is $-F$. The vertical component of this force is $-F\sin\theta$. Let's assume that $\theta=90^\circ$, i.e. the opponent goes straight up. We see then that the vertical component of the force has a magnitude of 770,000 Newtons. Assuming the person has the same mass as the opponent, he will then have a kinetic energy of $4.235\times10^9\text{ Joules}$, the equivalent of roughly [one ton of TNT](https://en.wikipedia.org/wiki/TNT_equivalent). This will be aimed directly at the ground. That's like aiming two [Tomahawk missiles](https://en.wikipedia.org/wiki/Tomahawk_(missile)) at one spot ($\theta=30^\circ$ would be as much as one). [One is bad enough](https://www.youtube.com/watch?v=dWOoHx2c3i4). Both opponents may walk away unharmed, but there should be a fairly large crater. [Answer] These are to the best of my knowledge, the physics of super human strength related to punching (if there is such a thing): To start, when a human being punches, he/she generates force by one of the following: Torque - generate centripetal force by swinging the weight of the arm Leverage - pushing off the ground slightly and/or against one's own weight or speed In order to generate escape velocity, a human being would not be able to use those means because: Torque - The person would have to anchor the centripetal force with their body somehow, so unless they have super-human obesity (or density) or super-human physics, they're not really going to be able to aim using torque. Leverage - The person's feet and body would sink into the ground like a bullet and their punch would miss (which would be funny) So basically you need to answer this question: Where does the super force come from and when does it work? Where does it come from? If the force comes ex nihilo or in another way that does not obey the laws of physics, then all bets are off, but then you can have someone get punched into the atmosphere (totally worth suspending physics). A Dilemma Let EV = Newton's required to generate escape velocity You are stuck in a catch-22 I like to call the super-cancelling dilemma. If a person can punch with super human force, they can also absorb that amount of force (dissipating it "into the universe" or whatever) otherwise they have to break the laws of physics. So the puncher generates EV newtons by creating and simultaneously absorbing that force in his/her own body thus reaching the punchee with the force and transferring it. But here's the catch 22... If BOTH brawlers can absorb that amount of energy, they will not be able to force each other at all (EV - EV = 0), and the fight [wouldn't appear to be super human](http://www.washingtoncitypaper.com/columns/straight-dope/article/13039270/straight-dope-the-physics-of-punching-someone-in-the-face "wouldn't appear to be human at all") unless a regular object or person got in the way in which case it would be obliterated. The one brawler would need superhuman means, so the ball is back in your court since you got them into this predicament to begin with - now you have to get them out. The fight would look normal if they could absorb exactly the same amount as they could dish out, so if one is slightly stronger than the other but multiplied by hundreds of thousands of Newtons, you're talking about guys flying through the atmosphere again, but that means the one person must be roughly twice as strong as a super-human who can generate EV or more force (2EV - EV). If there is some fluctuation (as there is in a real fight), and that fluctuation can be in the thousands of Newtons, now you're talking about a one punch fight. One guy punches punches with EV + 1 Ns and the other guy absorbs Ev - 1 Ns of force. Well, if they are immutable, now you've got that guy flying with ~2000 Ns in whatever direction he was struck. Further considerations If a punch misses, can that puncher "reabsorb" the force even though they absorbed it once already to create it, or will that person go flying in the direction of their swing? Can the super-human body absorb at the same ratio as a regular human? if so, it will appear like a normal fight. If not, they'll obliterate one another at the first punch with a only a tiny variation relative to the normal godly force. If there is an angle, deflection, speed, or interference at all, you need to recalculate (in other words, you are facing a myriad of variables) So No, that's not possible based only on the parameters you gave. They would need a way to create and absorb the force at the same time. ]
[Question] [ This question is inspired by NASA’s recent [TRAPPIST-1 announcement](https://www.nasa.gov/press-release/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around/). Imagine two planets orbiting a star with orbits very close together. At the nearest point in their respective orbits they are only 1 million kilometers apart. Both planets lie in the habitable zone and both will evolve sentient life. Much like humans these two distinct species create structures, roads, and farms. They start fires, cut trees (or their flora equivalent), and divert waterways. As they progress technologically they create larger cities and farms and their effect on the world becomes more noticeable. So too does their ability to observe each other. Both species are curious, and naturally they train their telescopes on their clearly habitable neighbor. At what technological level will they most likely become aware of each other? What would be the first signs that would betray one species’ existence to the other? I’m interested in varying technological disparities between the two species. If one species is neolithic at what point will the other species discover them? Will it require manned/robotic expeditions or could powerful telescopes detect them? What if both species are roughly on par technologically? What is the technological breakthrough that will reveal the other? Bonus question: are there any plausible scenarios where the technologically inferior species could become aware of the other species’ existence first? Assume for our purposes the atmospheres of both worlds do not obscure astronomical observation any more than the Earth’s does. --- Note: this is distinguished from [this earlier question](https://worldbuilding.stackexchange.com/questions/68119/at-what-stage-would-we-have-detected-sentient-intelligent-life-on-the-moon) by: * the separation is 4× greater * the civilizations may be at different levels [Answer] The answer depends on both civilizations' technological levels. If one civilization has the use of electricity and it lights up its cities in the night, with the distances as close as 1 million kilometers those cities would be seen with unaided eye. At the distances of 20-40 million kilometers a simple telescope would be needed. If one of civilization uses fossil fuel lighting (similar to XIX century Earth) and builds sizable cities, a more advanced telescope would be needed. Other effects of civilization - like deforestation and large scale farming, can be easily detected, but it would take an advanced level of theorizing to prove that those are not natural phenomena. Detecting neolithic civilization would be a tough task. Without actually sending a probe to another planet, advanced civilization can detect changes in vegetation, but it would be difficult to prove anything conclusively. However, if the distance between planets can be indeed as close as 1 million kilometers, even small settlements could be seen. P.S. Answer to the bonus question - advanced civilization has not only advanced means of exploration, it has more ways to give itself away. A neolithic civilization can observe night time illumination of their more advanced neighbors, while those neighbors still don't know what kind of species inhabit another world. [Answer] I'm going to assume one planet has advanced to around our current level and place the other at different times. * Our neighbours are cavemen: Even with [exoplanets](https://en.wikipedia.org/wiki/Extraterrestrial_atmosphere#Exoplanets) we have looked at the composition of their atmosphere with an interest for discovering life. This would lead us to note an atmosphere prone to developing life and, as such a search for that life. Robotic craft would make it first, at the very least a satellite would be put in orbit in order to verify the existence of life. * Our neighbours are have discovered farming: The burning of large areas of land without much of a good reason for it to happen naturally would indicate the existence of life. * Our neighbours have tech a hundred years behind us: Radiowaves would be the easiest to get through, sending us a very clear sign that our neighbours are advanced. A hundred years ago we were just getting into sending long-range transmissions on a regular basis. As for your bonus question: There is no real reason for an obsession with life elsewhere, it could be that the more advanced civilization has stopped looking or never was. The use of radio-waves will be an early point of contact across the world so one civilization may start detecting radio-waves of the other when they first discover the technology - the other world would expect a lot more noise in their signal from other emitters on their world and, perhaps, not think anything of it whereas the more backwards world would have a clear detection of some language being transmitted or at least a non-random signal where they expected to pick up nothing. [Answer] The telescopes weren't enough strong until around WW2 to detect a nearby civilization visually. Consider the long suspections about the Martian life, simply the valleys of the Mars were suspected as irrigation tunnels. If the remote civilization has already radio communication, it would be detectable with our radio telescope many, MANY light years away. Our radio senders would be detectable in an around 80 light year big sphere around the Sun (only from not much more, because earlier we hadn't radio). 1million km isn't very much, it is only around 2.5 times of the Earth-Moon distance. An another Earth 1million km away would be higher as the Moon. We would see that it is green even with free eye since the ancient times and probably it would be clear for us that also there is life. Note, so nearby independent orbits are impossible, the planets would too strongly affect eachother. Most probably, after some significant "perturbations", they would go into a more distant orbit. There is another possibility (much smaller chance) that they would go to orbit around eachother and become a dual planet. (The third possibility, their collision, is closed out: planets are much more distant as their size.) The dual planet situation wouldn't be a catastrophic event for the life on them only in the case if it had happened before the existence of the life, and even their common orbit would make the life possible on them. In this case, the planets would fast tidally lock. It would mean that the "other Earth" is always on the same point of the sky, and 1 day would be 1 month. It would be a much slower rotation as we currently have, thus life similar to ours is possible on such planets, only if the planets have a much denser atmosphere. Ideally, I would suggest a much ticker nitrogen atmosphere (some ten times as on the current Earth), with same oxygen content as we have. On such planets, flying life forms (birds) would be much more common, probably a significant part of the whole biosphere would live in the air. Maybe flying plants would also exist. Intelligent lifeforms could be also flying ones (our birds can't develop because they have no place for a bigger brain). If the intelligent race of the planets are like human, they could fly even with ancient technologies, like with ships. Falling down from a high elevation wouldn't be dangerous, because the drag would avoid to accelerate to too high speeds. There would be much more strong winds. [Answer] According to Wikipedia's article on [visual acuity](https://en.wikipedia.org/wiki/Visual_acuity), normal vision can resolve not quite 2 mm line pairs at 6 meters. That's 3000:1 So at a million km, the Eye Ball, Mark I would be able to see features 300 km across, if they were high contrast. This would give you the gross outlines of continents, major weather systems, but would not reveal cities. A set of 10 power binoculars brings that down to 30 km. At 65 power you're down to 5 km. This is the standard field model 3.5" Questar field scope. Still dodgy for all but the biggest cities. However, the construction of large dams that impound lakes would be visible. (Not the dam, the lake.) Once they start an industrial revolution you may be able to see ash plumes from industrial areas. The first spectrometer on Earth was 1802. Once absorption lines were discovered, then the variation in gas composition from analyzing light skimming the planet would reveal industrial activity. This [answer](https://astronomy.stackexchange.com/questions/9911/what-is-the-typical-resolving-power-of-the-largest-optical-telescopes) suggests that .5 to 1 arc second is the atmospheric limit. That's 1/3600 of a degree or a target distance ratio of about 1:200,000. At 1 million km, we're talking 2.5 to 5 km again. The Hubble can do about 20 times this, so now we're getting down to city block size. Caution: The power of tides goes with M/r3. Two earth mass planets 1 mega-km apart will have 1/27 the tides due to distance, but 80 times the tide due to bigger mass compared to earth moon. Net result is about 3 times the present lunar tides. Caution: Close orbits tend to be unstable. See Wikpedia article on orbital resonance. Orbits tend to work better with simple ratios. Play with orbital dynamics models. TRAPPIST-1 planets are very close together, but also very close to the star. Postulate that the close encounters keep the planets from being tidally locked to the primary, or that they get locked in resonance. (Mercury is locked in a 3:2 resonance for example. 3 'days' = 2 'years' Given the very short orbital periods of TRAPPIST-1 this sort of period would be fine. ]
[Question] [ ## Setting So for generations a ship has been traveling through space. After reaching their desired destination you are left with a group of people who have been used to their largest spaces being no more than a few tens of meters across. If I were to suddenly send them out to populate a planet with vast swathes of land where you can see for miles I would expect some degree of agoraphobia. ## Problem In my story I want the arriving population to only have a minority without this fear. How would be best to explain/provide a counter measure to the agoraphobia? ## Causes The causes of this fear would be, of course, the unknown: * Information overload: I imagine seeing for miles rather than only a few meters would be difficult to process if you lived the majority of your developing life on the ship. * No fixed paths: The ship would have been huge but to reach somewhere you only had to keep to a (probably well sign posted) corridor. The contrast a planet's surface provides is huge - the fear of getting lost would probably also be so. * Routine: I don't imagine there is much variation in where to go on the ship, the change in what you're doing and where you're going is a cause of much distress to most people suffering from [agoraphobia](http://www.nhs.uk/Conditions/Agoraphobia/Pages/Introduction.aspx). * It isn't abnormal: In our society treatment for agoraphobia often includes being assisted by someone who knows and understands your problem but doesn't have it themselves. This wouldn't be possible if you are one of the majority - they may not see it as a problem. [Answer] # Virtual Reality headsets The immersive experience will prepare your travelers for the tasks and duties they're expected to preform upon arrival. But only if the things they think of. For you and me the sky is so common we don't even think of it. Why would we warn our descendants about it? For people who grew up without one how could they possibly know it's a thing to think of? It's only the slackers and weirdos who waste time looking up the impractical things like "sky" and who spend hours just experiencing it. I could imagine people on a generation ship specializing and prioritizing productive survival training. A doctor learns about every known disease and surgical procedure, but what about new diseases? What about previously unknown infection vectors? What about common sense and problem solving in chaotic situations? None of these things would occur to someone rigorously training to be a doctor after growing up in the controlled context of a generation ship. Most training is solitary (you learn your occupation by listening to lectures and doing VR lab work), but maybe some kids cut class and cobble together games so they can mess around in the new environment. Strategy challenges, capture the flag in an alien jungle. The adversarial experience in the new environment hones problem solving skills in a small group of otherwise incompetent gamers. Turns out these slackers are now the colony's best hope for survival. I'd expect other neat limitations too. People trained in an immersive VR simulator would have finely honed motor skills and problem solving in fixed or expected situations, but they could fail miserably in situations requiring improvisation or unexpected and novel sights sounds or situations. (What do you do with a snake? How do you deal with rain in your eyes? For that matter how do you know its OK to breathe when the air is full of so much water?) [Answer] Agoraphobia is generally a defensive mechanism to some trauma. Therefore, aside from a few people who may have had something happen while doing an EVA, there shouldn't be much incidence of agoraphobia. If someone was going to be agoraphobic, they would probably be shut-ins on the ship, not leaving their rooms. I would recommend that there be photos of the "exotic" home and destination so they can get use to the concept of a sky. Otherwise, there may be a few who can't perceive it through a lack of a frame of reference. Also, I picture a few people who keep staring up at the sky worried that it might spring a leak (big spaces with no bulkhead doors are a bigger risk on a ship). Though, from my standpoint, if you have a population that is use to living on a giant moving space station, why are you interested in a planet? Go for the asteroid belt and make more giant moving space stations. That's what everyone thinks of as home now. [Answer] Actually I don't think you'll have that problem, for a simple reason: It is very unlikely that the planet will be a perfect match before doing some serious terraforming. Therefore after landing, people will likely mostly stay in the space ship and in new buildings on the planet that "extend" the spaceship. Until people can live outside those enclosed habitats, at least one generation, if not more, will have passed, and the new generations will be used to occasionally leaving the enclosed buildings in spacesuits (or, if the match is close enough resp. after terraforming has almost finished, even without spacesuits for short times) from time to time. Speaking about leaving in spacesuits: I guess that your space ship needs inspections of the outer hull, and occasionally repairs, so at least some people should be used to open space, an experience compared to which standing on the planet should feel rather constrained. If you fear that people might develop agoraphobia, you might schedule regular visits to the space ship's outer hull for everyone during the travel. ]
[Question] [ Regarding the Many World Multiverse, everything I've been reading (and searched on SE) seems to assume that each (parallel) universe is, at this moment, the same age. For my story, I need this to not be true for my time-traveler. By making it not true, is it no longer within the scope of the Level III: Many World (Multiverse) interpretation of quantum mechanics? Is it within the scope of some other theory? [Answer] I don't think there's any reason you couldn't stagger "now" between different worlds, but you may have some explaining to do. In most multiverse theories, the argument is that anything that could have happened did happen, just in an alternate universe. This includes all sorts of things that could have happened, and the vast majority of timelines look nothing like ours! Consider that there's been billions of years of events happening from the big bang to the present. That's billions of events that could shape the evolution of the human race... or prevent it from occurring at all. There's no way to know the numbers for real, but it's reasonable to assume that the number of universes where humans even exist are vanishingly small compared to the number of universes out there. This is all fine and dandy for exploring quantum mechanics, but for telling a story it's inconvenient. You don't have thousands of pages to document all the failed and boring timeline jumps that occurred before you found somewhere worth going to. So typically worldbuilders creating a multiverse handwave in an assumption that there's some sense of "nearness." Each universe has some sort of "neighborhood" of similar universes but with some small change. Typically these something that's easy for the reader/viewer to understand such as "Germany won WWII," even though quantum mechanically it's not clear why that would qualify as "near" our universe. But, nontheless we use this nearness or sameness concept to make sense of our multiverse. It brings some sanity to the worlds as we explore them. You will have to use this process in your own literature to tame the wilds of the multiverse. However, you don't have to use anyone else's definition of nearness. While it is common to assume "two points at the same 'now' are near to each other in the multiverse," that's really a matter of convenience, not a physical law. If you want to stagger "now's," go for it! The one thing to be aware of when doing this is [Sanderson's First Law of Magic](http://brandonsanderson.com/sandersons-first-law/), which I quote so often I really need to have some notepad file up with it rather than looking it up every time! > > Sanderson’s First Law of Magics: An author’s ability to solve conflict with magic is DIRECTLY PROPORTIONAL to how well the reader understands said magic. > > > You will certainly be resolving conflict with your multiverse theories and whatever approach you develop to jump between universes. The better a reader understands this process, the more you can do with it. In your case, one question to ask yourself is "why isn't it different?" If timeline A is 5 hours behind timeline B, why is it that way? Why is it not timeline A 3 hours ahead of timeline B? Surely that is an equally probable staggering of "now!" If everyone is at the same time, justifying it is easy. If universes are staggered, you have a bit more justification to do. It's certainly not impossible to do, just something to be aware of as you go forward with a slightly less standard approach to multiverse theory. [Answer] ## Of course there are other theories. There's even one which is contained within the scope of the one who seem to wish to use: Level II of Tegmarks hierarchy. Which states that within the multiverse, there exists a infinitude of universes having each different properties to our own. Any number of properties could explain why the entire causal chain of a specific universe would be out of sync relative to ours yet be effectively identical other than in that one measure. If you don't want your "time-traveler" to be able to jump into worlds where the laws of nature are completely different (and where he would immedietely die if he were to go to them) and yet want an explanation for why he can't(or doesn't accidentaly do so), simply handwave the problem away by making whatever method you're using to hop realities only work with universes which are "compatible", that is to say ones with universal constants that are sufficiently similar to the original reality. This seems perfectly reasonable to me. [Answer] Short answer: There are 2 cases: either the universe splits with each measurement, or the 'path of measurements' of each universe is already mapped out, even though it measurement outcomes still appear probabilistic. In the first case, fundamental constants can be changed, allowing for different universes to appear to be different ages, although this is really a result of changing the (non-fundamental) laws of physics, so things just happen at different rates (if they even happen at all). Alternatively, handwave that the big bang is probabilistic and so the multiverse is constantly splitting into new universes, giving multiple copies of the same universes, only at different times. In the second case, big bangs can happen at different times, so different universes can be different ages as required. Long answer: As details about the various interpretations about quantum mechanics are fairly complicated, let's assume that there was a big bang at a multiverse time $t = 0$ (ignoring all the complicated details that this brings up) and that time travelling from a universe with multiverse time $t$ in that universe will bring you into a different universe, also with multiverse time $t$ in that universe (if not, then you don't even have a problem to begin with). Now, there are two possible ways that things could go using the Many Worlds Interpretation (MWI): 1. Every time that a measurement (in the quantum sense of measurement), the existing universe splits with everything in the new universes being the same, except for the measurement outcome, so that everything that could happen does happen in some universe within the multiverse, which originated with the big bang 2. There was a big bang for each universe. The measurement outcomes for everything that will be measured in each universe is already 'determined' in some sense, even though it appears to be probabilistic (a bit like [the two state vector formalism of quantum mechanics](https://en.wikipedia.org/wiki/Two-state_vector_formalism)). Perhaps each black hole contains another universe or somesuch, with the multiverse being the originally created universe, containing all the other universes Case 2 is straightforward - other universes can be younger or older than our own, depending on when it was created relative to our own. Case 1 is probably what most people think of when they think of the MWI. There are a couple of ways to solve this: 1. 1. (Messy) Things start to get a bit more complicated here, due to time. Here, a universe that only recently split off from our own is going to be almost the same as our own, including having the same time. However, a universe that split off right at the beginning may have different physical constants (actually a level II multiverse and entirely equivalent to level III). Now, if (as an example) you change the speed of light, $c$, things will start travelling through time at a different rate than in our own universe due to relativity, so although the alternate universe will have the same cosmological time, it will appear younger or older, although at the risk of the universe being considerably different to our own. Having said that, the universe is billions of years old and assuming you only want to travel a few hundred years back (or forward), the changes might not need to be that great. Although you're still messing with the fundamental constants of nature, which is messy... 1. 2. (much neater, although currently even less provable science and requires more handwavium.) What was the big bang? Well, no-one knows, except that it was extremely hot and that it suddenly expanded. Now, things like entropy would cause this expansion, which suddenly makes the whole process probabilistic. That is, at the time of the 'big bang', the universe splits into a universe where the big bang has occurred and another where the big bang hasn't yet occurred, Despite this, the 'multiverse time' is still somehow increasing (defining time this close to the big bang is an issue) and so within the multiverse, there are an infinite number of big bangs and so there is an infinite number of worlds just like our own, only at a different time according to that universe, even though the multiverse time is the same. [Answer] Piers Anthony's novel Orn in one of his early trilogies had a multiverse set-up where different parallel universes existed at different time rates. If you have time travel, there's no reason why there shouldn't be time differences between parallel universes. In fact, if you were constructing a model to explain time travel a multiverse where parallel universes were at different times (or ages) would work well. Time travel in parallel universes has less problems than most other forms of time travel. No causality violations for starters. Worrying about whether this concept works in or is contrary to quantum mechanics or any version of a scientific theory about multiverses is irrelevant. Unless you want to publish it as a paper in Physical Review. If you are building a fictional world, you are allowed to make it work however you want it to; though it does make sense to try and avoid any obvious errors. Time relations or differences between parallel universes is an open question. Science doesn't have an opinion either way or another, therefore, you're free to do whatever you like to make your story work. [Answer] What is the “same moment” between different branches? If travel is possible between different points in time across branches, does the idea of synchronization even make sense? What kind of observer is saying the same time on different lines are “lined up” or “not lined up”? In [The Proteus Operation](https://en.wikipedia.org/wiki/The_Proteus_Operation), connection between the two ends of an established time link (which will always connect different timelines!) was complicated by the fact that the past end was experiencing time faster than the future end. This would provide a sense in which different timelines share a present; the point at which the rates are the same at each end of the connection. But the idea of a universal present moment doesn’t even exist in our normal single universe! It makes sense that there is no implicit lining up of timelines, unless you provide reference for what that actually means. And then you can push that meaning in interesting directions to make more surprising consequences or unusual situations. [Answer] One reason parallel universes are generally "the same age" is that it is often portrayed as similar universes being grouped closely together - variations on a single timeline being "easiest" to reach (usually demarcated by different decisions at critical points) - though this is generally for story-purposes rather than physics, as I understand it (it being more fun to tell stories of really-nearly similar universes, or really, really different ones). That being said, I have read stories with different universes in different places in their timelines. Sometimes it's a function of events being placed differently - some event happening "soon" or "late" means the timing of effects and aftereffects will be shifted up or down the timeline, rushing or delaying the historical events that shape the setting. Or events, history, can happen slightly closer together, or further apart, so even though the broad strokes look the same, the "now" is placed in somewhat different places because the events are a bit shifted about in time. Sometimes, it's a function of some really subtle alteration of universal constants - like each second being a quarter or tenth or a nanosecond longer or shorter, which may not make an observable difference in a person's observations, or life, or perhaps even a hundred lives, but over the universe's lifetime will lead to very similarly-developing timelines being in different places in their timelines (or even different ones, though usually you don't need to be meddling in universal constants to just make the universes very different). So the timeline can be off by a few years, or a few hundred, very easily - as long as the parallelism of the timelines being developed justifies the universes being "close together" despite the very fundamental differences in their universal constants. Or to take it in a completely different direction, one of the theories of the multiverse have new universes branching off at critical decision points - thus the "new" universes are much younger than the ones they branch off of, even if they share the same long history up till that point. In case I misunderstood what you meant when you wanted the universes to be different ages. [Answer] If you want to head into the fantasy side of things, the Fae worlds are generally considered to be running at different time rates. I see nothing wrong with different universes having different rates of time. None of them would know unless someone were to travel from one to the other and back. To have any kind of "parallel" universe, the difference in time rate would be very small. After all being 1000 years ahead or behind is a very small fraction of 13B years. The time rate differences would probably not be noticeable (or even measurable) over short periods. If the time rate difference was something noticeable (like 2x), you would have a case where the Sun had long ago gone nova or, in the other direction, the Sun may be condensing our of interstellar gas. ]
[Question] [ I want to have a species based on humans, where everyone is born as female, but switches gender to male later in their life. Assuming that transformation takes 4 years (\) hermaphrodite is born as woman, at 27 starts transformation and at 31 becomes man. Assuming that anatomy of sequential hermaphrodites is equal as possible to humans, would humans outcompete hermaphrodites assuming same technological level in the stone age era. Advantages: Nearly double population growth (humans have longer fertility window but it starts to drop after 27) Disadvantages: * Infertile during the transformation period * Smaller number of physically strong soldiers * Might be less willing to take risks, since there's no young men to do that (\) I plan to ask is this realistic time period in separate question [Answer] Well, if this species is anatomically similar to humans, you have to consider one of our species' biggest design flaws: maternal mortality. In pre-modern times, it's estimated that up to one in twenty births resulted in the mother's death. If this is the same for your species, it's easy to imagine that for much of their history they will experience quite an unequal sex distribution among the population, as many women won't live long enough to make it into manhood. But the other factor that skewed gender distribution in human history was warfare. In our species' history a big war would reduce the proportion of young men. In your species, there won't be any young men, so there's a question over who fights this species' wars instead. If it's the older men, then this would be a further factor that would reduce the proportion of men in the population. But my suspicion is that it would be young women and girls who'd primarily be press-ganged into military service. This might make your societies more apprehensive about fighting wars, as it's much harder to rebuild your population after losing a critical mass of your mating-age females than a similar number of mating-age males. Once your species develops medical technology on a similar level to ours, the gender disparity is going to completely flip, as more women survive childbirth and more men live older lives. Your societies will face an unprecedented shift where the gender split goes from 60% female to 40% male, to 40-30% female to 60-70% male. For a civilisation completely unused to this, it would be fascinating to see what this sudden surplus of testosterone would do... [Answer] I'm going to go out on a limb here and say Not if the hermaphrodites do it right* TL:DR: Don't assume that just because women can breed that they will try to. Many other answers here are applying modern (or at the least, human) sociological values to an otherwise alien society. If this sexually hermaphroditic society develops a different approach to gender roles (or, more likely, the entire concept of gender) and adopts a more arbitrary caste based system, then you will quickly see similar roles to men/women developing but split along caste lines. Strapping young girl? Military caste. Go forth, try your best to kill or be killed. Take risks. Don't breed, as death in childbirth is the worst shame a warrior can know. If you grow old enough to become a man then you have an awful lot of experience and can be used to train the raw recruits, not to mention stud the next generation of warriors into existence. Likely to get killed in the first skirmish? Don't worry: There's always a need for the working caste. Feel free to breed if you want to, but don't expect any special treatment from the other castes. You're here to primarily support the other castes, including taking care of other people's children if required. If you grow old enough to become a man then bully for you. Wide hips? Good pedigree? Mother has a history of twins? Breeder caste. You get food, protection and your pick of the men. You're likely going to die giving birth, but hey, at least you perpetuated the species. If you don't die and manage to live long enough to be a man then clearly you're good at this whole 'giving birth' thing, and the next generation could use some of your genetic material. Go forth and multiply. This system requires more social interaction than the human system, and as such tribes can be expected to be more closely knit. If the death rates are similar to those of the human's you're trying to outcompete then you should come out ahead of the game (or at least drawing) by having specialised roles that are not gender specific, and as you'll likely develop specialties pretty quickly (your 'alphas' will likely be female, your wise men will be just that, you won't have any arbitrary traits defining social structure from the get go) your social structure may well pip humanity to the post and make up for any breeding disparity. Plus it would make for a social structure that is simultaneously incredibly PC and hugely discriminatory. Disclaimer: I mostly wrote this answer to be contrary. I have no idea if this would occur and, in fact, no way to simulate the social evolution of a pre-historic population, but it's a possible outcome! [Answer] # The key human advantage is risk-taking In human societies, men are generally less important to the reproductive process than women. Therefore men can be risked without incurring much risk to the population as a whole. This is a powerful advantage for developing technology and for expanding through violence. Women, in general, had to reproduce to keep the species going; thus was true for all of history until the 1800 when improved nutrition and sanitation allowed many more children to survive. But men were never that necessary; one man can do the job of 10, so to speak, when it comes to making children. Therefore, an effective society will utilize its young men in high-risk, high-reward occupations to attempt to gain competitive advantage for that society. High-risk, high-reward things might include hunting dangerous things (like mammoth for food, or lions to keep them from eating your kids), long distance trading for valuable rocks from far-away places, or fighting your neighbors for prime land to steal their womens. # Risk taking humans can out-compete the more fecund sequential hermaphrodites in direct competition So applying this principle to your sequential hermaphrodies, they are likely to be at a significant disadvantage in direct competition with humans. Sure they can reproduce faster due to having more women around, but if they fight battles, they have a relatively higher penalty for losing men in combat because there are proportionally less men. Each man lost in combat has relatively more negative effects on the ability of the society to produce children, compared to humans. They also don't have the available expendable people to send out to do scouting or trading, unless the young women do this...in which case they are forfeiting their advantage in reproductive rate. Finally, it is worth pointing out, if combat is more or less concentrated in the males, the males of the sequential hermaphrodite would have significantly less experience with combat when they reach their 30s; and experience is the primary advantage of older men in combat and as combat leaders. [Answer] Can they breed with humans? Many scientists believe Neanderthals didn't go extinct but were absorbed through interbreeding with traditional humans. Given that your population has fewer men than women it's possible that the females of your species might interbreed with human males especially if your mails stay behind and the females go to war leaving their husbands behind perhaps for years. As a side note I don't think this species population what really grow much faster than humans. Most human women continue breeding up till their thirties and some even up to their mid-forties men can continue breeding from puberty to their sixties. Whereas in your species the females only viable breeders until they reach 27 long before a human female would be still capable of breeding at this time. As for your men they are capable of breeding till 31. That's twenty-nine to 30 years of Lost potential when it comes to greeting. So in terms of population I actually think human population would be much higher [Answer] If [life expectancy tables](https://en.wikipedia.org/wiki/Life_expectancy#Variation_over_time) are correct, and the average life expectancy hovered between 20 and 30 for most of history, most of your females would not have an opportunity to live long enough to become a father. Since males would be rare, they would be much too valuable to risk in war. If we assume the average age of death is 30, and the people don't become fertile men until age 31, more than half of your population would not survive to reproduce as males. This would almost certainly remove the possibility of pair-bonding. A human couple can reproduce at age 14 or so, while among hermaphrodites, 14 is the age of the female, while 31 is the minimum age of the male. If we are looking at human physiology as an analog, then most of the society would be females and thus on average be both [physically weaker](https://en.wikipedia.org/wiki/Sex_differences_in_human_physiology#Skeleton_and_muscular_system) and less aggressive their human counterparts. Humans would reproduce faster, be more aggressive, have more aggressive males to hunt, fight, and compete than the hermaphroditic society. They could tolerate more men being killed. Furthermore, human females could tend to the young while the men fight and hunt, while there could be no such division of labor in the hermaphroditic society. Edit While infant mortality does skew the life expectancy statistic, it is undeniable that life expectancies were much lower long ago. Consider maternal death at childbirth. In countries where moms do not have access to quality medical care at birth, about 1 in 6 die in childbirth ([Unicef](https://www.unicef.org/newsline/02pr59afghanmm.htm) note the rate is per birth, not over her lifetime.) [This](http://johnhawks.net/weblog/reviews/life_history/age-specific-mortality-lifespan-bad-science-2009.html) article does a good job at refuting the Live Science piece quoted in the comment. In it, the author cites age of skeletons in the catacombs. > > if human lifespan had really not changed in 2000 years, then 35-year-olds shouldn’t have left their skeletons very often in the Roman catacombs. Unfortunately (for them), we find those 35-year-old bodies. A rough estimate (gleaned from tomb inscriptions that give ages) is that half of Romans who lived to age 15 – and therefore escaped juvenile mortality – were dead before age 45. > > > In a world where there is no antibiotics, no surgery, no dental care, no false teeth, no refrigeration, no stable food sources, and danger at every turn, death came quickly and often. A scratch could lead to sepsis. Food could turn in the hot sun and lead to food poisoning. Starvation, war, plague, and violence were constant companions. ]
[Question] [ I created an incredible machine that can reduce my size infinitely. (or not, that's part of the question) This is some kind of spaceship-like machine that makes everything inside smaller and smaller every second. I started the machine and look through the window. What will I see? Is there are any limit or theory about how small something can be? (It's ok for me to use comic books or literature, but I prefer actual science more) Assume we can make ourselves smaller, not dying in the process. It's more about what we can see and if there is a limit about how small other objects can be. [Answer] This is a partial answer, but yes, there is very much a limit to how small something can possibly become in our world, which stems from basic physics. It's called the [Planck length](https://en.wikipedia.org/wiki/Planck_length), and its value is approximately $ \ell{}\_P \approx 1.6162 \times 10^{-35} $ meters. It is derived directly from other fundamental physical constants, so unless you are messing with the basic underpinnings of physics in your world, then your world will work the same way as ours (and if you do mess with those basic physics in your world, chances are good that you are screwing something up and rendering the universe completely non-viable). Now, as a living being, you are going to be facing massive difficulties long before you reach this size. For example, an [atomic nucleus has a size on the scale of](https://en.wikipedia.org/wiki/Orders_of_magnitude_(length)#1E-15) $10^{-15}$ meters, $10^{(-35) - (-15)} = 10^{20} = 100\,000\,000\,000\,000\,000\,000$ times larger than the Planck length. A [helium](https://en.wikipedia.org/wiki/Helium) atom has a diameter of about 62 pm ($6.2 \times 10^{-11}$ meters), another several thousand times larger; and the DNA helix has a diameter of about 2 nm ($2 \times 10^{-9}$ meters), nearly 100 times larger still. You are going to be far smaller than an atom long before you even approach the Planck length magnitude. As for seeing things, the wavelength of extreme ultraviolet is about $4 \times 10^{-8}$ meters; now, recall the [single or double slit experiment](https://en.wikipedia.org/wiki/Double-slit_experiment) of high school physics. Even at molecular scales, handwaving away the issue that there probably wouldn't be any way to form any sensory organs at all because of the limited size and amount of material, you'd likely be looking at extreme x-ray at best before you have any decent optical resolution. It isn't until you get to around $10^{-6}$ meters that we start seeing sizes that can support [life](https://worldbuilding.stackexchange.com/a/36615/29) as we know it; for example, Wikipedia gives the [typical size of a bacterium as](https://en.wikipedia.org/wiki/Orders_of_magnitude_(length)#1E-6) 1-4 micrometers ($10^{-6}$ meters). Compare the answers to [How small can an organism get?](https://worldbuilding.stackexchange.com/q/36613/29) What might be considered human-scale sizes begins at something like $10^{-3}$ meters (1 mm). You may also consider [For how long must a molecule remain stable to be considered “stable”?](https://physics.stackexchange.com/q/61018/14091) on Physics SE, which, while not about the same thing, does offer some examples for scale. [Answer] --- ## What is Size? As far we[1] can tell, the most fundamental particles may not have size (in the testable three spatial dimensions to which we are used to[2]). But we have distance between particles, and that distance is what actually gives size to macro objects. Now, there is some known distance between particles if we have some idea of where they are. And for we to know where they are we need to measure their interactions. For example: we can know where an electron is if we can make it collide with a photon, or we can know where proton is if we can make it collide with an electron, etc. We have discovered that the position of particles is not deterministic. Yet, with enough measurements we have been able to create a model of their position probability distribution with virtually no error (as far as our current measurement instruments are concerned). Of course, reaching virtually no error is archived by adjusting the theory to the reality. [1]: By "we", I mean human kind. [2]: If particles are - or are made of - hypothetical strings that have size on other spatial dimension which we are currently unable to test is another thing. But - you say - we know the diameter of electrons and protons... No, we don't. The way we make these particles interact is by the electromagnetic force. That is, the particle don't really collide... they repel! The way we have to estimate the diameter of particles is by the principles behind the [Rutherfords Gold Foil experiment](https://youtu.be/thnDxFdkzZs?t=261). In detail, the experiment is as follows: shoot alpha particles to a thin gold foil, and detect where the alpha particles go after it reaches the gold foil. From the experiment, it is observed that the alpha particles are scattered. The explanation is that the atom of gold has a nucleus that repels the alpha particle causing it change its direction. So, if we want to estimate the size of the nucleus we have to [analyze how alpha particle behave near the nucleus](https://youtu.be/L0q8u0N5K_Y?t=860). Note: the link above explains in more detail and goes on how to calculate the diameter. What is important to notice of this method of measurement is that it is based on the repulsive force caused by the charge of the particle. It is what we know as “charge radius”, and in practice is only serves as an upper bound to the size of the particle. So, even if we know the charge radius of a particle, we only know that if the particle has any size it must be smaller than that. So, as said at the beginning: as far we can tell, the most fundamental particles may not have size. But protons are made of quarks! Yes... we call "quarks" the thing that protons are made of. But we cannot measure how far apart a quark from another quark is when they are bound. In fact, [there are no free quarks](https://medium.com/starts-with-a-bang/there-are-no-free-quarks-ddec8cb831ea#.bm6ab8iq0). Even knowing the distance between quarks, we have the problem of the size of the Quarks themselves. Quarks just happen to be the perfect description of the interactions of the particles that we claim that are made of them. --- ## Introduction to the photoelectric effect When a photon interacts with an electron, it gives it energy that displaces the electron to another orbital/electron shell/bond. If a photon doesn't have the energy required to displace the electron, then it simply doesn’t do it. That means that each material there is a given set of amounts of energies that a photon would have to have to interact with it. If the electron that is displaced belongs to a bond, it breaks the bond (which is understandable if we consider a bond a shared orbital) in which case light is serving a catalyst of the chemical reaction that ensues. Also, displacing an electron may move it to medium that allows it to move freely, guided by the local electric field. That is how light can create electric currents. We will come back to the idea that photons interact with electrons. --- ## Visible But even if something interacts with light doesn't mean it is visible. It may be the case that you are unable to focus on it, or perhaps it is too dark (not enough light) for you to see. In fact, you want to use light of shorter wavelengths (higher frequency) to be able to focus on smaller object. Here is where the shrinking part of the question becomes relevant: as you becomes smaller your eyes become smaller, and thus its curvature increases! And with it changes its focal length, also decreasing! A shorter focal length means that you can now focus on smaller things (in particular if we consider that now the eyes are closer together). Yet, smaller eyes also mean less light entering the retina, so as you become smaller the world becomes darker. --- What about the eyes? Let's see how shrinking works: 1. As you decrease in size you lose mass. At some point you die, the reason being that your body can't no longer sustain itself. No. 2. As you decrease in size you increase density, and at some point you will die because chemistry stop making sense (e.g.: hemoglobin in your blood being smaller than the oxygen you breathe). 3. As you decrease in size you make atoms smaller. You push proton to proton and the nucleus become radioactive, the critical mass for nuclear chain reaction becomes smaller and smaller... until Boom. No. 4. As you decrease in size the space from orbital to other orbital decreases (the nucleus remains intact). These happen [1]: * The energy required moving an electron from one orbital to another becomes smaller. If less energy is required, then you become sensible to lower light frequencies, which move the visible spectrum to shorter wavelengths [2]. * Since less energy is required to move your electrons, you will burn and die because all your body will be subject to uncontrolled chemical reactions. 5. As you decrease in size you survive using unobtainium macguffins handwavium, or similar technology. You will be able to see thanks to the [Sword of Omens](http://thundercats.wikia.com/wiki/Sword_of_Omens) or any other technology indistinguishable from magic that you may have at hand. [1]: I’m unsure of the order in which those happen – this is all speculative, since we can’t do this kind of shrinking. [2]: Larger wavelengths mean lower frequencies (to infra-red and radio waves). It should be noted that you need higher frequencies to be able to focus, and you will be seeing lower frequencies. So, it is all blurrier and blurrier. --- ## Weird Science Good! You got the most recent version of the unobtainium macguffins! 10-11 m You first approach the size of an atom. Since you are a complex system and not a single particle (and you are using your unobtainium macguffin handwavium) you are not affected by decoherence. Also the atoms around you are pretty much stable, so no big deal. You continue to repel atoms. The only weird thing is that some particles would be able to tunnel through you. What do you see? Well, there is light everywhere, it is making the electrons jump from an orbital to another, and then the electrons jump back and release the photon again. This is happening everywhere because things are agitated! I mean, temperature exists and it is not absolute zero! So, everything would be bright, uniformly bright, no shape. Furthermore, repulsion happens by exchange of virtual photons, will you be able to see them? Who knows‽ Maybe you get into a bond and join a molecule. --- 10-15 m Next you approach the charge radius of protons. I don’t believe you would see anything; the effect of light pushing you is greater than any illumination. At this scale the classical idea that light spreads uniformly from the source is no longer relevant. Instead a photon interacts with you, or not. --- 10-26 m You next approach [the size of your event horizon](https://en.wikipedia.org/wiki/Schwarzschild_radius)! In the past light had a chance to be reflected out of you, but now you are so small that light that would have miss you due to your size is trapped by your gravitational force. Furthermore light going out of you won’t go very far anyway (if something smaller than an atom can be considered far). You no longer see anyway. --- 10-35 m I don’t know why we bother; you are a micro black hole anyway... Finally you approach the Plank Length – The Plank Length is clever bit of calculation, but we don't really know what it means. Can something be smaller than the Plank Length? As far as we know there is no such thing. We don’t have means to measure it; in fact, we believe it can't be done. And for any practical purposes it doesn’t matter if something smaller is possible. The Plank Length is a popular idea to cite, but saying “nothing can be smaller than the Plank Length” is just flat. What we know about the Plank Length is: * If you have a black hole with Schwarzschild radius of that size, its [Compton wavelength](https://en.wikipedia.org/wiki/Compton_wavelength) is the same size. Two hypotheses come from this observation: 1. All particles are actually tiny black holes. 2. A black hole that small would just dissolve as radiation. We don't really know. * We reach complete uncertainty at that distance. The accepted model is that uncertainty is a fundamental property of the universe (and not an emergent phenomenon or a technical limitation) - as I said near the beginning: the position of particles is not deterministic. That would imply that any displacement of less than a Plank Length is meaningless. Writing this I came up with an interesting idea: any movement of less than a Plank Length could be considered to take no energy, and thus happens spontaneously, and instantaneously. Speed at Plank Length could be meaningless. ... You are a micro black hole anyway. --- ## Another way to shrink Let’s say that you can change the curvature of space-time in an unnatural way. That is, a way that doesn’t follow the curvatures that are described in Einstein’s equations, such that you can have a small area such that if you measure distance traversing it, it is less than you would calculate if you measure distance circumventing it. This is often referred to as “Tardis Space”. Now, I do not pretend that there is a discontinuity in the curvature of space-time. Instead the curvature must be continuous. Looking from outside at a reasonable distance to the inside of the “Tardis” it would look as if everything inside is smaller, almost fitting correctly the apparent external size, you may think it is a miniature set. As you approach the inside start to appear larger, at the moment when you are at the door you can see the inside almost at full size. Now if you turn around and look to the outside, you see that it becomes giant as you walk in, but the inside is now apparently of normal size. What I’m describing is an effect of [gravitational lensing](https://en.wikipedia.org/wiki/Gravitational_lens), exaggerated. Appropriate time dilation still applies. Times passes at a lower rate while you are inside. Now I understand why in some RPG videogames when you walk on the over-world you are a giant, then you step on a tiny town and when you are inside it is of normal size… and the day cycle seems to stop. It should be noted, that even with this weird curvature, what is being described is gravity. I find it hard to wrap my head around that idea that this thing pulls you in… but that is what General Relativity suggests. If that is true, then it is also true that any object entering experiences tidal forces, and thus you may not be able to survive the walk in. And we want this effect at infinitum. Yeah, black hole, right there. Note: I said the curvature for this does not follow Einstein's equations. You could get away with a curvature that doesn't extend outwards to infinity. That would be interesting. ]
[Question] [ I asked in [this question](https://worldbuilding.stackexchange.com/questions/35630/how-can-i-achieve-2-separate-rebellions-for-the-same-cause) how I would achieve two rebellions for the same cause only to find out my basic premise was wrong and that having only one rebellion is the less likely of the two. Going over this I now wonder how I could prevent the more likely option. How can I prevent more than 1 rebellion from forming? --- To Molots request; I am dealing with an caste empire system, the lower caste citizens are widely unhappy with the system and I want a rebellion to form. The problem is that it is a vast empire, spanning oceans and thousands of miles. With no way to communicate, I find it unlikely that if multiple rebellions form, that they would unite. So I need a way for only one rebellion to form. [Answer] In case this hasn't been apparent yet, I'm a dark fantasy writer. So expect the 'bad guy' point of view in this answer. # Your starting point: a leader. No rebellion, no revolution, no nothing ever starts without a 'visionary'. Someone with a silver tongue, that knows how to sway people -- the masses, preferably. This person will know the hardships of the people they want fighting alongside them. They'd need a compelling story to really stoke the fires of the people -- though not necessarily a verifiable one. Example. [Amon](http://avatar.wikia.com/wiki/Amon), from Legend of Korra. Or frankly, Trump. Bad examples, with arguably dark intentions, but people that speak to the paranoia of the people all the same. # Your rallying point: a common goal. This part comes in two parts, true to history. 1. First is the surface goal. This is what you tell the masses, what you allow everyone to hear and talk about. It needs to speak to the masses. So if they are oppressed? Freedom therefrom. If they are hungry? Food for them and their families. If they are poor? Equality and fairness, so that everyone can reap the rewards of their labours. For Amon, it was freedom from benders. He played on the fears of those who couldn't bend, showed them what a renegade bender could do to people that couldn't bend -- and they are oh so arrogant, too! For Trump, it's far more insidious. He plays on racial bias, the desire for "a great, Christian nation", and so many other things. 2. The hidden goal. This doesn't always have to be bad, it could be simple lust for power. Or it could be something noble -- i.e. true freedom from oppression. But every movement has one. Even if it's as mundane as no longer wanting to work the fields anymore. # Your lieutenants: inner circle. No matter how suave the figurehead, they need capable lieutenants to get the work done. After all, how many leaders fight a war on their own? Whether a battle with guns an spells, or a battle of wits in their palace among the noble you need to overthrow. You need a solid team backing you to get you in and out in one piece. These are the people that need to balance your leader. If the leader is "a lover not a fighter", then the lieutenants need to be the best warriors available. If the leader is "the strong, silent type", he best be relegated to the housekarl and let the Thane take over (Skyrim reference, in case someone did't get it). # How to do it: the plan. Start off small. If you are setting this in a city, start by recruiting in some neighbourhoods. Be sure to start off with the rambunctios ones. The idealistic youth is usually a good first target, though typically harder to control over long periods. Gather a following. It doesn't matter how small, even if it's just your lieutenants at first. Then you start with the biggest issue: 1. Funding. No rebellion/revolution can go unfunded. So you start off by acquiring the funds you need. Whether this the 'Robin Hood route' (rob the rich to feed the poor), the Salvation Army route (all donations are welcome, whether monetary, time, or materials -- we'll put it to good use) or lobbying like you're gearing up for an election. You need someone you can trust to handle this (it doesn't end well, if blackmarket weaponsdealers don't get paid as promised). 2. Food. No one fights on an empty stomach. So make sure you keep yourself and your people (well) fed. And if they ever so much as catch wind that following you leads to a worse life than they currently lead, you'd best have one hell of a brainwashing scheme in play to keep them loyal to the cause. 3. Arms. No war is fought without both pen and sword, you'll need both close at hand. Get these three things, and more followers will follow. If only because you feed them, they will follow. # Size really does matter: Scaling up! Once you have the basics (every step before this one), then you need to start getting strategic. However, this is the step that is most world/plot dependent. So a few plausible routes: 1. Divide and conquer. A house divided unto itself cannot stand. So create that divide in the enemy. Find out every possible division point amongst them, and drive a wedge in there. Stir up old rivalries, play on racial divides (but make it look like they are the ones doing all the dividing, you're the good guy after all!). 2. The monster that goes bump in the night. Nothing freaks people out more than the Eldrith. The monster you cannot see, the monster you cannot comprehend. So don't give them an enemy, or a note, or a sign that it's your group doing any of it. Let their imaginations run wild, and make sure you keep an ear to the ground to see what that is turning into. But to make this effective, you need to make your hits big. Assassinations with no sign as to what happened. Stores getting robbed, but no one sees anything. Start small, let the panic simmer a little. Then hit bigger and bigger targets each time. More than that, if there are other groups that are known for causing trouble, or simply groups you want to fall and hard: set them up. Make it look like it was them, let the autorities take them down, hard -- preferably violently. This weakens them, while it keeps you out of range. The endgame? That depends on your plot. Maybe it doesn't have one. Maybe, like the Joker from DC, the anarchy is the endgame. [Answer] The best way for this to happen would be for a rebel organization to have formed at the implementation of the caste system. One cell, probably in the capitol where we assume the caste system was first and most harshly implemented, gradually spread into the surrounding countryside, each new cell keeping in contact with its mother-cell, which kept in contact with its mother-cell, all the way back to the capitol. This idea is based on the assumption that pre-caste-ian society was at least tolerably equal for the two emerging castes. When the system is first implemented, many people will be reluctant to accept it. People, as a whole, are slow to change their ideas, so especially in isolated areas far from the capitol, the upper caste will probably be slow to really squash the lower caste. This gives you a chance to get a rebel network set up before the lower caste actually begins to rebel. The capitol is the perfect place for the start of the network as the caste system is no-doubt strictly enforced from the beginning, meaning that the rebellious lower-casters actually have a reason to begin forming a rebel network. As the caste enforcement spreads out, the rebellious attitude will follow it, probably on the backs of the capitol cell's preachers/recruiters. By the time the caste is harsh throughout the nation, the rebel network will be in place, providing a perfect framework for an organized rebellion. This also means that you can focus on one cell, or on the rebellion as a whole, depending on the size of the group you want your characters to be in. As the caste system becomes harsher, the lower caste will inevitably get fed up, but unless there was already some sort of network in place, they would simply form multiple, fractured rebellions. [Answer] # The Empire and Rebellion share the same enemies While it seems difficult to make sure there's only one rebel group, it's easy to imagine a situation in which one rebel group is vastly predominant over other ones. In fact, there are many examples. For instance: 1. Democrats v. Republicans -- The parties may be "at war," but they both agree that third parties such as Libertarians or Marxists in power would be far worse(I'm not taking a stance here about whether that is correct). Their combined influence and agreement on this is more than enough to effectively silence third parties(though if both parties' leaders are highly disliked, a third party may gain some traction). 2. Catholics v. Protestants(in pre-enlightenment Europe)-- They may have considered each other heathens, but they both considered everybody else to be heathens as well. If there was ever a serious threat posed by a third religious sect, say Eastern Orthodoxy or Islam, they would have united temporarily(as Western-European Christians) to crush it. 3. The Kuomintang v. Mao Zedong -- They were bitter enemies, but they were united in national identity. Considering the Japanese to be rebels against Chinese dominance of the east(which could kind of make sense in a twisted way), the KMT and CCP united temporarily to crush the third faction, and only resumed warring when it was deemed that the greater threat to their society was defeated. To integrate this concept with your example, I would suggest that in your world there are really only two political ideologies that have any popular support with the commoners. The first is the caste system currently in place, of course. The second is unlikely to be something as radical as democracy or Socialism, or even a republic, and is more likely to take the form of a military dictatorship by a benevolent secular ruler, a theocracy, or some kind of fragmented city-state model. It could be that your world is young enough that only two forms of government have every really been tried, or it could be that the records of previous civilizations have been lost, or it could be that your society is extremely conservative. But for whatever reason, both the Empire and the Rebellion consider any third political ideologies to be far, far, more dangerous than they consider each other, and so will temporarily unite, for instance freely giving each other intelligence about third factions, just so they can be stamped out. # Starting a third rebellion would be really difficult, and not worth the expense 4. Mac v. PC -- (This one is slightly different, and probably less applicable to your scenario). There's enough variation in consumer preference to keep people switching from Mac to PC, or vice versa, when one side slips up or has a breakthrough, but there's not enough variation in consumer tastes to justify the existence of a third for-profit competitor. Apple and Microsoft both have huge infrastructures dedicated to producing a quality product, and an upstart third OS company would not have the resources to create a product as good, and no realistic chance of gaining a large enough number of users to generate the necessary revenues to become a competitor. In essence, the market is only big enough for two, based on costs of production, and amount of variation in tastes. Applying this to your scenario, it could be that most people don't care what replaces the current system, inasmuch as they really just want the current system gone. Hence, there would be little support for a third faction, as people would just see it as a subtraction of resources from the rebellion that could be used against the Empire(In the same way that people saw Ralph Nader as just a subtraction from Al Gore's votes). Because starting a rebellion is very expensive, and everybody thinks the current rebellion is working out for them, there wouldn't be enough interest to generate a third faction. [Answer] Why would multiple rebel factions not communicate? You only need the tiniest thread of contact. The situation you're describing is (though somewhat vague) similar to the declining period of the Roman Empire. The world's foremost military power had hired mercenary armies and tried to pay them with worthless, debased coins. The mercenaries rebelled and became bandits. Roman citizens fleeing heavy taxation also ran to the hills and became bandits. The key is that the forces of oppression, the military occupiers, were thrown into chaos. That allowed rebel groups to communicate and consolidate. The same thing happened in the American Revolution. I think you need to figure out what your Empire is doing wrong. Governments that rule through coercion always have some fundamental flaw because the resources they need to subjugate a population increase exponentially compared to the size of the government itself. This is why, for example, the Soviet Union starved even as its technology and infrastructure improved. But back on topic. You only need one successful rebellion. This becomes more likely over time as the Empire expends resources putting down multiple uprisings around its territory. One successful rebellion can spread to adjacent territories. Then it becomes a question of what will be their strategy and tactics, and what kind of force and propaganda will the Empire use against them? The key to a successful rebellion is a charismatic leader. A folk hero. The lower-caste citizens need someone they can believe in no matter what lies the Empire tells. Someone whose name becomes a rallying cry. That hero might be a tactical genius, but he doesn't have to be. He can win through attrition while the lower-caste commit innumerable tiny acts of sabotage. The tighter the Empire squeezes their grip, the more territories will slip through their fingers. Muad'Dib. Spartacus. Dragonborn. [Answer] There is something unique or distinctive about the far province where the rebellion actually takes root well enough to start spreading. Maybe at the far edges of the empire there is more “feeedom” as in freedom from the overseer’s constant attention and sympathy among the general population of the annexed nation, but the system is being forced down from above by the new rulers. What they didn’t count on was that the merchant class was already powerful, literate, organized, and connected, and was previously a middle class with high class mobility based on the individual’s own successes or failures. So, being forced into an oppressed lower class pidgenhole will not go over well. These are the international traders and businessmen, and the upper crust of those are wealthy—the nouveau riche disrespected by the new regime, not the titled official rich endorced by the new government. To summarize, the specific social condition in a far flug empire composed of diverse original cultures allows it to happen there. ]
[Question] [ or; # Pass me my gryphon pants please. > > His high school racial studies were kind of a pain, Billy thought. Spending the day as a unicorn may have made gym class easy, but it just made trying to write on the chalkboard in math class a pain… also all the girls looked at him funny. Still, football was fun when he was a troll, and if he did well his parents had promised to let him try flying on the vacation over the summer. > > > The above sort of gives a taste of what I’m trying to achieve from a first person perspective; a modern Earth analog with a blase acceptance of the ability to transform. The scenario is that at sometime in the recent past, a brilliant/mad Scientist developed a Scientific/Magical method of literally changing a human into something else. animal or fantastical, "Anything go's" inside certain constraints. The specific rules about how this works and what someone can change into are less important for this question. The limits of the change run a lot along the lines of mammalian-esque forms and of no actual mass changes (regardless of what it looks like), and nothing that strictly couldn't exist without magic; winged humans sure... but no flying winged humans. Also assume, mostly for story reasons, that most transformations are sane; a person won’t end up as a slime and washing down the drain to the local water treatment plant. This obviously is going to take a fair bit of work to ‘sell’, especially because a familiar, modern day setting is a requirement, but given: * The setting focus is on western society; Europe and the Americas. * Its available to anyone that wants it at a reasonable price. (Reasonable is cellphone level of cost, not sports car level) * This is a divergent world from our own recent history, not a fantastical one. ( As far as anyone can tell its the same up until [x] date.) * The setting must maintain and appearance of the current day one we live in. (no apocalypse) * Transformations can be as temporary as a hand stamp or as permanent as a tattoo. They are NOT clap-clap on, clap-clap off changes, and there is a minimum time of hours-to-days, and a functionally unlimited maximum time. * The tech/magic behind the scenes really is kind of irrelevant beyond making the assurances that are needed so people feel safe with it. * There needs to be less divergence rather than more in the overall world; airliners rather than flocks, rush hour rather than stampedes. This ability needs to be a fairly modern change to prevent unanticipated changes to [the] world/events. * You can’t clone someone else's specific form/body, you end up along the lines of “what you would look like if you were born as [x]” * humans act as humans do; events still transpire as historically they did until they no-longer believably can (ugh, timeline stuff) --- Within these constraints, and the understanding there there will always be fringe groups that call it ‘evil and/or unnatural’: # How do I convince the largest cross-section of people that this is a socially acceptable and even a normal thing for a person to do? How far ‘back’ do I have to go to put the point of divergence? The 1980s? 1960s? Further back? --- This question can be more generalized as “how do I convince any large group to accept something totally new and different” I suppose, but the idea of transformations gives scope as to how alien the "new and different" is. I can hand-wave how it happens and was developed in the first place, as well as the reasoning by letting having people have access to it, but I’m having trouble setting up the scenario where it’s accepted by people at large. To me, Humans have a historical tendency to shriek at anything new and then climb a tree. let me reiterate; I can come up with gobs and gobs of reasons why this can fly off the rails, I'm not asking how it won't work... I'm asking how I got there. How do I make something so radical and different into something that's viewed the same as getting your ears pierced at the mall? I want to avoid making it something that's “always been that way” as I feel that realistically, the longer this ability is around, the more things will change and the less recognizable modern life is. I get that something developed a week ago just can’t get accepted that fast, and certainly this is a candidate for "never-accept", but I want (mostly) whole-sale adoption. Yes I do have the fantasy tag, but still, bonus points for believability. [Answer] Understand, this is complete guesswork. However, I'd say it would have to have started somewhere in the 60's. You have to think about this in the same mentality as women's rights, the change in mentality regarding people of color, or homosexuals today. Some of these balls started rolling a long time ago, yet the issues are still not completely resolved today. In a way, I think the civil rights movement will have a much easier time due to people's attention being drawn from them to the shape-shifters. (after all, you may be black, but you're still human, not like that freak over there!) You can also assume that there would be a lot of religious intolerance, especially in the middle east where such people might be regarded as demons, and that only more recently would the Pope have taken a more lenient stance on the issue. Now, let's talk acceptance: I can imagine the military picking up on this rather enthusiastically (troll soldiers in Vietnam, etc). This right here will play a huge role in getting the ball rolling. I can also imagine this procedure picking up a lot of popularity in lieu of plastic surgery. People "altering" themselves to look more buff, prettier, better endowed, etc. Last but not least, these changes are going to spike during the years of the hippies. People will embrace their drug-induced visions and change themselves to look like all sorts of fairies, etc. Another aspect is that gangs might start turning themselves into demons, or orcs as a form of demonstrating that they belong to a fierce group. Prison inmates might be "changed" such that they are instantly recognizable as inmates, and move so slowly that trying to break out of jail is pointless. The fact that change is so potentially useful would go a long way toward pushing society to embrace it. Eventually it could end up a bit like today: with it being accepted in large metropolitan areas (the more Liberal areas), and looked down on in the more conservative states. [Answer] Looking at smartphones in our daily lifes and social situations I'd wager it taking at most 2 to 3 generations until it's broadly accepted. The most important thing here seems to be the generation that first grew up with it, not the early adopters themselves. As soon as these `transform-natives` are in positions of public influence (e.g. teaching younger generations, writing news, etc.) acceptance and use will easily spread and become a normal thing. [Answer] Most probably, I think it would be safe to assume the technology was discovered within the later half of the 1900s, say around 1955 or so. I would like to point out that if this is a world where mythical creatures existed even before the transformation tech was discovered, the education system would probably not look like the one you potray. It doesn't seem fair to other species to conform to the "human" way of learning, and most probably, there exist different systems for differently able species, or one system that caters to all species without bias. I would think such technology could not be easily made commonplace in the setting you describe, except where its use is practical,recreational, or otherwise justified. I guess construction workers and such would find it useful to assume a form with more musculature, and if you just want to run, why not just turn into a cheetah? (I am assuming that the technology can also be used to transform into non-mythical creatures). there are probably lots of other examples out there, but these are what come to my mind. In the end though, I feel the type of world you imagine would not be very practical. [Answer] There needs to be a law against transforming into a close duplicate of another human. You also reliable way to identify a person even in a transformed state, for their own safety. From you description it sounds like I can transform into an almost exact duplicate of a different person. So I could commit a crime and he would be blamed. When my friends talked to me they would never know if I am me or it was someone that was currently mimicking me. You need a way to reliably identify a transformed person. What if I want to experiment with being a deer and then a hunter kills me by accident. I could also rob a bank under the guise of a troll then transform back to hide. Some industries would collapse when we can easily change our appearance (cosmetics), some would ban or limit transformations (sports), some would love it (movies). [Answer] Like most innovation there will be the glass half empty and glass half-full people. Since your question is how to get it accepted, there is two possible angles: * get trend setters to promote how cool it is (here look at how Hollywood stars, journalists,... promote any new idea) * provide immediate tangible benefits On the tangible benefits, I could see medical ones. You mention that you cannot clone someone form/body but you could for sure take the form of a healthy person (free of any modern disease: cancer, high blood pressure, ...) but also possibly tall and strong... If you want to make the switch happen fast you push the medical angle. Let's say now that H5Nx (replace here with any possible fast countagious crowd disease) breaks out and only a small population of Amazonian villagers are immune healthy carrier. You could consider they have leaved for hundreds of years next to the birds which act as the natural reservoir and developed immunity. Let's say that 50% of people from other communities once contaminated will die. When the pandemic broke-out, in your not so long ago past, labs around the world were helpless and people were left with the choice to either shapeshift or take a 50/50 gamble with their lives... This should give you a pretty strong adoption rate once the pandemic is over. Dealing with the after-pandemic effects... People most likely would stick with the form/shape which gives immunity but would most likely develop advanced forms of social norms to keep people which used to look different from "entering" their groups: special handshakes, special ways of wearing glasses, hats, ways of calling things, ... ]
[Question] [ ## Context Wizards built a civilization on a barren planet. More details [here](https://worldbuilding.stackexchange.com/questions/39775/space-wizards-city-is-it-sustainable). --- ## Magic Batteries The population of the planet is between two and four million wizards, but not all of them are born equal. More than half of the population don't produce enough magic, or lack the focus, to actually cast spells. They still produce some magic, that can be harvested and stored in magic batteries. The collected energy can be used to power things like sentient automatons/robots, flying boats, atmospheric spells, etc. To charge a battery, people have to carry it around with them, see illustration bellow (pardon my poor drawing skills). [![Magic Back Pack](https://i.stack.imgur.com/SAb6t.png)](https://i.stack.imgur.com/SAb6t.png) Depending on the person, a battery can take from a few hours to a couple of month to charge. Once fully charged, there's no difference between them, no matter who charged it. If not damaged, batteries can be used and recharged indefinitely. ## The battery market I still don't know how to regulate de battery market. My goal is to have most low-level wizard walking around with a battery strapped to their back. I'd also prefer this society to not be totalitarian. Because of the context, I already have troubles keeping the government from controlling too many aspects of its citizens lives. It's already in charge of the maintenance of city-sized atmospheres and manages the terraforming process. Here the worst-case scenario would be the government forcing people to charge batteries. So here are a few possible ways I found to organize the battery market : 1. Batteries are cheap Empty batteries are so easy to produce, even poor people can afford to buy their own and sell it to whoever they want once full. Advantages : Free market, next to no involvement from the government. Most low-level wizards would choose to carry one, since it would be an additional income for very little work. Problem : This society lives on a not-fully-terraformed planet, and I'm afraid any kind of good or resource being abundant and cheap would sound weird. 2. People don't own the batteries they're carrying Batteries are owned by businesses, rich families, or public institutions. They pay people to charge their batteries. Advantages : Sounds maybe a little more realistic than the previous option. Low involvement from the government. Problem : This would be an oligopsony (few buyers deciding the prices), leading to lower market prices. This could deter some people (who have an average-paying job, or who would take too much time to charge one battery) to enter the market. 3. The first battery is free When they turn sixteen, every citizen gets a free empty battery from the government, and when they sell a charged battery, buyers are required to give them an empty one, in addition of the payment. Like for the previous options, people aren't forced to do it, but choose to if they want the additional income. Advantage : Resolves the problems of the two previous options. Problem : Heavy government involvement (even if it doesn't decide the prices or forces people to wear batteries). --- ## Question Knowing all that, how should the magic battery market be regulated? (Feel free to build from one of my solutions or to give an entirely new one) [Answer] No Regulation needed. The battery comes in two pieces: an extractor component which stays mounted to the host's back and a removable "bottle" which holds the magic. The bottles are just blown glass with a particular glyph carved on them, so they can be manufactured in vast numbers, making them effectively free. Charities could give bottles away to the poor to allow the recipients to earn a living. Extractors might come with a special blue bottle which can only be removed by the manufacturer. The new host wears the extractor till that blue bottle is full, then returns to the manufacturer who receives its contents as payment for the device. One blue bottle pays for one extractor and once the blue bottle is removed, other cheap bottles can take its place. From there, the host owns whatever magic is produced. [Answer] Another free-market possibility: a mix of commercial and personal battery chargers. Poor people can wear a locked device, which earns them a fraction of the value of the magic when they swap full for empty. As people get a better magical credit rating they get courted by higher-class providers who pay a better rate. (The longer it takes you to charge a device the less desirable you are to the providers, as the return on investment is less.) You can also buy an unlocked device that lets you sell your magic to the highest bidder; once you own your own device it doesn't matter to the buyers how long you spent producing the magic. (There is a parallel with locked and unlocked mobile phones in the US market that might not be obvious to people in countries with a different business model.) The trick is making it profitable and convenient enough for even weak magic producers to wear a device. All that assumes that the harvested magic is not useful as-is, but is going to magic refineries. If I want to wear a magic concentrator so I can fly to and from work with my daily magic budget then the financial picture changes significantly; I benefit from wearing a battery even if I never bring magic in to be deposited. In that case the OP's thought of parallel tanks starts to make more sense, where the owner of the device siphons off a certain amount. (Another American analogy comes to mind, sharecroppers who paid rent on their farms with a portion of each harvest. Note, though, that sharecropping is historically associated with an assortment of predatory legal and financial practices.) A less-abusive way to get into the magic market would be to have all schools fit kids with fully-locked magic collectors, in part to help pay for schools and in part to tamp down on magical student horseplay. Once or twice a week the kids would have "magic class" where they learn how to do common tasks with magic, just like I learned cooking and sewing and B/W photography in junior high school. That would help spread the social idea that everyone wears a collector to not "waste" magic. ]
[Question] [ I have a character who loses her forearm. To up the cool factor (and because this once happened in a dream of mine), I'd like for her to dip her stump in gold. Would this actually result in gold covering her skin, or would this just burn her skin/flesh and do nothing otherwise? I'd like a relatively realistic answer, but magic does exist in-universe, and she is a magic user. [Answer] Combining the answers of @Lacklub and @user16295 I would suggest the following... Your character uses tar to cauterize the wound. This works and saves their life. However walking about with tar covering your arm, or that commonly not-quite-appealing skin-patching that happens, is not very cool. Gold would be better, coolness factor goes up a lot. But as has been concluded that would do very bad things to the stump. So combine the two solutions. Have them make a mold of the stump when covered in tar and from that fashion a gold cap for the stump. They may then use tar as a "glue" to keep the gold cap attached to the stump. [Answer] I assume you're imagining liquid gold. Yes, gold can cauterize a wound. The only requirement to cauterize is heat. However, there would be problems. 1. It shouldn't be a lot of gold. If there was, then it could melt away more flesh / bone than you want. Gold melts at about 1000 degrees C, and metals have a high thermal conductivity. 2. Gold won't bond to skin. In this process, the surface layer of everything is being killed (this isn't necessary when cauterizing to clot blood, but would happen with liquid gold). Even if the gold solidified on the surface, it would eventually be shed because the top layer of skin will fall off. You actually lucked out on toxicity. Pure gold is non-toxic and not very reactive. [Answer] I think the only way you would get gold to bond to the skin would be to make ink with a high content of gold dust and tattoo the gold into the skin. Covering a stump with a solid, permanent, cover would (at best) probably result in infected pressure sores and end up requiring amputation. [Answer] ## Try silver rather than gold. Gold is toxic, silver is [naturally antibiotic](https://en.wikipedia.org/wiki/Medical_uses_of_silver). Melts a little cooler, only a scorching 961.78 °C. It probably still won't bond to skin though so it'll still need significant added magic. (For comparison, tar which was normally used to seal such wounds, melts at about 55-60°C) [Answer] How did she lose her arm? If it was a magical blade that was cursed to eat her flesh/bone, it could corrode/create holes in her bone while eating back the flesh. This would provide a way for the gold to hold onto her bone/arm. Otherwise the gold would just fall off as the damaged skin was shed. Picture dipping an unblemished stick in glue, it would just pull off when dried. But drill a few holes into the stick and the glue then becomes effectively a part of the stick, the only way to remove it is to break the stick. [Answer] I could give you a solution, based on a documental. In this case an elephant's fang was cut, and also some minor fractures in it. So the keeper ordered somebody to make a metal inlay to be attached to the remaining fang and this stopped the elephant's pain. As when you go to the dentist and taps on a tooth... So, keeping that in mind, if you take gold or silver (after you decided which would be less toxic) and attach it to the very bone (it could be larger than the flesh) and make an arm, and provide with some means to move as a normal arm (such as hinges). It would reassemble the Star Wars movies, or I-Robot, the one with Will Smith(who has a metal arm). ]
[Question] [ Similar to this question, but on the galactic scale: [What would life be like for the common people on a libertarian planet?](https://worldbuilding.stackexchange.com/questions/35160/what-would-life-be-like-for-the-common-people-on-a-libertarian-planet) My specific questions: - How could a libertarian-minded galactic government be structured? \* - What would be the extent of the government's influence between worlds? \\ - How would citizens exercise voting rights under this government? \\\* In this Quora answer, which imagines what an Objectivist utopia might be like, <https://www.quora.com/Objectivism/If-everyone-were-an-Objectivist-what-would-society-look-like-and-how-would-it-function>, we get some extrapolations: * Government would be restricted to police, military, and courts * No entitlements, or regulatory agencies of any kind * No Fed and no inflation * Paper notes backed by hard money would be issued by private banks Finally, here is a brief, worldbuilding scenario to set the stage: I imagine a capital world, with a world government similar to a representative democracy, that decides to begin interstellar colonization, once relatively cheap interstellar travel is made possible. A variety of corporate charters are arranged between the government and private industries to assist in carrying out these expeditions to settle colony worlds. Eventually, these corporate charters are successful through a combination of support from the capital world and bootstrapping. Ultimately, however, the charters reject the legislative authority of the capital world, and they band together to supplant its ruling body. As a result, the capital world's government is reduced to a purely administrative role that best suits a libertarian ideology of governance. The worlds once under the control of the capital world's government become the property of the corporate charters, and a new ruling body is established to mediate economic(?) relationships between owners. `` Suppose there are 500 systems, most of which are owned by a variety of publicly-owned and privately-owned corporations, wealthy families, or extremely wealthy individuals. In general I am assuming that it's necessary for worlds to interact/trade with each other, and that the cost of moving resources between them is not any more tremendous than the cost to move resources between countries today. `` Let's assume that FTL travel is possible along a heretofore undiscovered absolute frame of reference, and time travel isn't possible by using it. You can get from the edge of the galaxy to the galactic center in a few months, but the more expensive your ship the faster you can go. Pure information can travel with this technology 10x faster than the fastest ship. Individuals own spaceships that have the capacity to travel within a star system in much the same way people own cars today, but traveling between star systems requires more expensive spaceships that only corporations or really wealthy individuals might own (comparable to the availability of private airplanes to individuals today). `` There are no sentient aliens, only humans in this scenario. Also relevant: [How could a galactic empire work?](https://worldbuilding.stackexchange.com/questions/23513/how-could-a-galactic-empire-work) [Plutocracy 101 - Business Governance for Dummies?](https://worldbuilding.stackexchange.com/questions/26967/plutocracy-101-business-governance-for-dummies) [Answer] How would a Libertarian Galaxy differ from a Libertarian Planet?** * A planet has a finite surface area. Many libertarian models tacitly assume that there is infinite land out West, where nobody lives except for injuns who don't count (because they don't claim land the libertarian way). The galaxy might not have infinite space for expansion, but it comes close enough that you can see infinity on a clear day. * A planet can have near-instant global data exchange. You can set up things like public key verification of contracts, reputation networks/checking, debate on political issues. In your galaxy, it can take weeks or months to get an answer back. * A planet has a single ecosphere. If John Doe starts a steel furnace, or to farm with pesticides, or to use ["reserve" antibiotics](https://en.wikipedia.org/wiki/Drug_of_last_resort) liberally on his poultry, everybody is affected. In the galaxy, John Doe risks only one planet if there are decent quarantine measures. So what might happen? * The legislative has planets elect/select representatives for a sector parliament, and the sector parliament elect/select representatives for the galactic parliament. Possibly with a few levels in between. I wrote "elect/select" because it might be something like the US Senators prior to the 17th amendment. (There is a classic science fiction RPG where that notion shows up.) * Entire systems could become "black hole" company towns. The only starships calling at the company port belong to the company, the only FTL communications systems belong to the company, and no information or workers get in or out, ever. On a planet, that would require fences and guards, and someone might ask questions. In the galaxy, it merely requires space traffic control rules. Or do the Galactic Government police show up to check? On what basis? * Can individuals claim an entire planet as their homestead if they arrived there first? If so, those who staked their claims early in the expansion phase, near the densely settled sectors, will be incredibly rich today. --- Addition: * A logical purpose for the central government would be to organize the common defense. Details depend on the threats. The question specified no aliens, but are there other human nations? If not, the military would only be needed for coast guard or police style operations. Better leave that to a police. * Many courts and police will operate on the planetary level, but there needs to be information interchange between cops. Will it be [FBI](https://en.wikipedia.org/wiki/Federal_Bureau_of_Investigation) or [Interpol](https://en.wikipedia.org/wiki/Interpol)? Investigating agents or just information interchange? That is connected to the question what galactic courts do. Is there any galactic law for the galactic Feds to enforce, or is it just planetary law? * What law applies to interstellar trade and contracts? Would the contracting parties select one of the involved planets, or is there galactic law? And what if the choice of one planet is missing? What happens if John Doe works and dies on World A, and then Jane Doe claims to be the heir according to the family law on World B while Jim Doe claims to be the heir according to the family law on World C? * Does the galactic government recognize and enforce human and civil rights? Which agencies do that? * Would even a minimum-regulation galactic government set standards for telecommunications and information interchange protocols? Are there galactic IP adress numbers? Identity papers with unique personal IDs? * Even if the galactic government does very little, it needs funding to do that. Does it control the collection of these taxes or is it dependent on planetary contributions? Either way, it would have to define accounting standards for the purpose of galactic taxation only. Such standards have a way of becoming de-facto standards for other purposes. [Answer] This type of government that you are suggesting in a sense reminds me of the Galactic Republic of the period stretching from 25,053 BBY all the way until the end of it by its demise by economic decline coupled with a rise in the presence of the military junta that Palpatine helped to support and ferment the foundation of his Galactic Empire. However, the key difference is that the Galactic Republic wasn't even a democracy at all as the chancellor was appointed by the senate and as the senators themselves were appointed to their positions of power by the kings, queens, dukes, and emperors and or empresses that supported their appointment to the senate. Additionally, I strongly believe that the Galactic Republic should not be compared to the United States both culturally as well as economically but rather to that of the Holy Roman Empire but without the religion as such. More so than ever, the Galactic Republic was a type of feudal confederacy that happened to be technologically advanced but socially backwards. ## Besides the Galactic Republic It should be noted that your model of a libertarian multi planetary interstellar corporatocracy would lead to a lot of problems. Though the idea of this is quite interesting as something like this is most likely going to happen in the next century or two as part of the expansion of our domain. The first problem is the fact that any large structure of corporate power without regulation from the government can lead to abuse by those who work at the lower end of the scale in this system as they would be more vulnerable to exploitation. Without a doubt, it is the dream of those who want to create a world with an abundance of resources and no taxes that such an idea would come to fruition. Now, in spite of all of this and the possible socialist rhetoric, I have to say the idea of a small government in terms of its military hegemony would be a good thing that would stay out of matters concerning the smaller aspects to the colonies that they administer. But as with matters in correspondence to economic matters of justice, there should definitely be the government to administer such a thing. We must not forget that when the government is in control of the corporation, it follows down the path of two roads as taken from the wisdom of history. The first is that the people as well as small businesses and or enterprises hugely benefit off of this to the point were the monopolies are broken and that everyone is able to live a decent life for themselves. However, we should be weary of the fascistic form of government control over the corporation, which is the second as well as the more totalitarian path that only adds to the war machine of that particular ideology on a monstrous Orwellian scale without precedent. In summation don't be like Mussolini, Hitler, Stalin, Togo, or even the Sith Empire when it comes to matters concerning economics. But don't take the advice of corporate power either. Lastly, I'm open to criticism of the constructive type. [Answer] Let's say for a second that you don't have FTL. You still have [time dilation](https://worldbuilding.stackexchange.com/a/23559/8914). What does it matter if it takes a million years to cross the galaxy if you only experience two (for the whole galaxy)? What would happen is that instead of living on planets, people would either live in orbit around black holes (there are the only things basically that you can orbit near the speed of light) or in ships. People only occasionally visit planets. Basically no time passes (relative the ships) whilst there. The central planet (or black hole) can't control anything, since messages and ships travel basically the same speed. Additionally, its hard to operate a military in space. You basically have a confederacy. People can also just go by themselves on ships, sort of like a micronation. As long as you stay out of shipping lanes, you're unlikely to contact anyone. It's hard to have a strong central government under these conditions. Ships are their own entities, and most importantly, space is big. You can't stop free trade or regulate moral behavior. You would have to have a huge population explosion if you want enough police to police an entire galaxy (not to mention maneuverability, since you can only really change direction by slingshotting around a black hole). So, a libertarian country is natural, sort of like the wild west. [Answer] That depends on what sort of libertarian governance we're talking here. Are we looking at more of a [Nozick](https://en.wikipedia.org/wiki/Anarchy,_State,_and_Utopia) type 'Minarchist' state? Or are you thinking something more like a [Rothbardian anarcho-capitalist](https://en.wikipedia.org/wiki/Anarcho-capitalism) society? ### Minarchy Governance is limited to those set of functions making sure that individual rights (Life, Liberty, Pursuit of Property) are maintained and all transactions are voluntary. In an interstellar context, I find it unlikely that such provisions are enforce-able on intra-planetary entities (invasion is improbable, atmospheric bombardment to indiscriminate to be remotely ethical). So these governance provisions would be restricted to relationships between worlds: preventing and punishing military actions between member states, defending member states from outside attacks, and making sure that trade agreements between worlds were entered into on a voluntary basis. Worlds would be free to leave this charter at any time, and non-payment to the confederation would void their membership and protections ### Ancap Much like Nozick, but without a formal government. Instead, you would have multiple, private rights protection and arbitration entities formally engaging in and enforcing contracts. Trade agreements are entered into and registered with an arbitrator decided by both parties with the contractual obligations (and enforcement mechanisms, and funding for said mechanisms) built in to the agreements. Again, unless this state evolved organically on the loosely associated planets, it's not a system that can be imposed on the actual populations of the worlds in question. Anarcho-capitalism is an organic system of spontaneous order, and while it might exist on the member worlds, its non-existence in the member states would be unrelated to how the worlds themselves interact, other than that an ancap planet would likely have multiple entities represented in the interstellar environment, as opposed to one world trade/negotiation setup [Answer] My guess would be like a giant, hopefully slightly better version of the United States, a little bit more leaning towards libertarianism and conservative values. # The governments in general I'm going to say you will have a very very large representative republic with different levels of government, and probably a federation on the level of solar systems. Also, so many confusing electorates. ## Levels of government Like in the United States, you would have your state government. Below that, you might have county or city governments. Above the state you would have what is comparable to our national government, then a continental government, then a planetary government, then a solar system government. I would then think that you would have a federation, or confederation of solar systems. ## Elections Now you have to deal with elections, so people ar represented as they wish to be. This is kind of confusing, I'm not sure exactly how it would work. The people would probably vote in every election. A candidate would win a state by popular vote, then a country, then a continent, then a planet, then a solar system. These governments would also choose their representatives, and these two groups would reconcile each other to make decisions. The federation of star systems would simply choose representatives, to help interact with other members of the federation. Edit - Above the level of continental, there might be elected voters. For example, politician X has continually made decisions we like, and now he is running for elected voter. Each nation would elect its small group or single voter, and he votes on the global, solar system, and galactic level. The danger of this is that as you make your governments larger and larger, it becomes harder to connect to the individual people you are striving to protect. The closer the government is to the people, the easier it is for them to interact with it. For example, you go to every city council meeting, and you talk straight to the city about your needs. Then you go and vote for representatives of your state, who you can probably send letters to that rarely recieve answers, and you can attend their meetings and listen to what they have to say. And at every increasing level, you have less to do with the government, because more people are influencing the way the government is going. ## Court System I would think that there would be courts at every level, with appointed judges who are approved by voters, in the manner aforementioned. They interpret the laws and constitution hopefully in the way the people want. ## Legislative authority Despite what you said, a legislative part of your government is a necessity. No matter inclusive your constitution is, there will always be new innovations, loopholes, and practices that will no be covered. When these things come into conflict with your citizen's rights, new legislation will have to be made. Like threatening to fire your dependent workers unless they build a bridge over an active volcano wearing inadequate heat suits and hang form flimsy ropes. That catch on fire. Hopefully your legislative branch will have more restrictions on what it can regulate and how it gains approval. And not outlaw stupid things that make no sense, like almost harmless food dyes, how big your toilets can be, and helpful pesticides that help prevent bug spread diseases and have never been proven to be harmful to birds. Cough hack cough hack. Edit - To improve your legislative body, they might only be able to create laws regarding certain decisions the courts make. So someone who for some reason or another can only get one job, then sues the company because the volcano bridge building is extraordinarily dangerous. The legislative authority of the planet, let's say, then can outlaw whatever makes the practice so dangerous. (And no, I don't mean they'd outlaw volcanoes.) ## Responsibilities of government Government would have a lot fewer responsibilities than today. A very, very limited regulation on trade, enough to stop the volcano bridge building with flammable ropes. Religion would not play any part in the government, in any way. Although I think it would fall under freedom of speech. The government would also help to facilitate relations between the different branches and areas of the solar systems, on different levels. After all, different areas will have different laws. But their main responsibility, and the one the most focus would be place on would be ptoecting the rights of the citizens and making sure they are following the laws and that the laws are fair. # Constitution Your constitution is the most important part of your government, and it is the basis on which your entire government is rooted. It needs to be extremely precise, and delegate powers carefully. It would also help to encompass the ideals of th government, what is trying to be accomplished by it, and how to accomplish this. It would also tell what the government should not and can not do. Communication Edit - Wit regards to communication delay, to help with this, terms might be a lot longer, or elections might take a longer period of time. Unless you were to invent some kind of FTL communication, as you have done with travel. Or you could have galactic couriers, which head to the different solar systems and project news. ]
[Question] [ Future governments (1-100yrs) believe human civilization has de-evolved since the invention of the personal computer. Their points are: * People stopped socializing * People don't go outside * Global depression and anxiety levels at an all time high * Cyber crime flourishes * Humans stopped thinking and remembering things * The information age enables people to rebel against the government Therefore there is a world effort to completely outlaw the ownership of microprocessors for any uses. The only agencies allowed to own such computing capabilities are scientists at their lab (highly monitored) and the government (that includes banking and the stock exchange) Is it viable or even possible that the world could get together to enact such laws? Would there be a rebellion? Is this possible in our world? [Answer] Even nowadays it is impossible to perform in developed countries. --- Everything would change. For starters, if you ban microprocessors, you practically ban everything which works using electricity. Not only computers and smartphones, but dishwashers, washing machines, TV sets, radios, cars, buses and trains, aircrafts, non-analog watches... (The list is practically endless.) Some of those could be redesigned to work with non-smart technology, but that would mean a complete redesign. But there is more than that... Every office uses computers to handle data, and entire industries are based on computers and microelectronics. Modern industry would be useless without microprocessors, so hundreds of millions would lose their jobs. There is practically no area of modern life what wouldn't change with the ban of microprocessors. Who would care? There definitely would be a rebellion, because you wouldn't only take away basic comfort from people, but also their work. You (your foolish government) would try to mess with an industry with an enormous economical power. Tech giants like Google, Facebook, Microsoft and Apple are already more powerful than most of the old national-states and if they saw they are facing total extinction because of some retarded politician they wouldn't afraid to use all their money, influence over the media (don't forget, they actually are the new media), and voting power of all their employees and customers to stop it. (Also, don't have illusions; noone with an agenda like that can get into a position where they could make it real. Multinational industry would never let that happen.) --- But since your setup is not in the present but in the near future... Should I remind you that IOT (Internet Of Things) is slowly becoming a thing? It means everything you own will have some sort of processor technology; your clothes, your vehicles, your household tools, even the very structure of your house - which means if the "great purge" comes, humanity wouldn't return to a late medieval level, but to the very stone-age. No clothes, no tools, no houses. Instead we would have a huge problem: 7 billion people unskilled in agriculture and basic survival on a planet which could only maintain a few hundred million without complex planning and agriculture. --- So TL;DR: That wouldn't work. [Answer] Someone somewhere perfects non-nuclear(?) EMP bombs and some megalomaniac uses them on a continental scale. They don't quite destroy the world but the collapse of a continent's information networks brings mass starvation and hundreds of millions of deaths. I think after this, survivors and inhabitants of other continents will take a very different view of microprocessors. However, entertainment devices will not be top of the list. Controllers in the power grids and in automobiles will be. Then computers doing finance and bookkeeping. Back to manual switches, relay logic, electromechanical fuel injection, pen, paper and mechanical calculators. "Never again". It doesn't stop there, though. The removal of all microprocessors becomes the basis of a new quasi-religious movement. Something not unlike the Butlerian jihad is under way. I appreciate this scenario is rather different to the questioner's, but if a scenario in which the premise might come to pass is required, I think this one works. [Answer] In n-ty years from now, a quantum phingamaboob processor is intended, that can be integrated into every single cell of the body, giving extended longevity/probably extending to immortality benefits or a sort of post-death existence ("upload"). In order for that technology to work, other ways of restructuring entropic flow shall be banished and having the simplest life is the way to live longer.. guess there'll be a group of immortals wishing for pre-stoneage. ]
[Question] [ Allow me to shed some light on this subject (turns on lightbulb). Brief Overview of Magic These powers manifest themselves any time from birth to the end of puberty. These magical powers fall under seven broad categories. Air, water, earth, plasma (fire/lightning), plants, light, and animals. Animal magic is tricky, because living things resist magic. But, many animal mages can influence animals, and some can control dead animals (this is called necromancy and is a big societal no-no.) The strength and scope of magic varies from individual to individual. But, these are the most common in order. Earth, water, air, plants, animals, plasma, and light. These magical capabilities are like the show Avatar, the Last Airbender, in how controlling magic works. However, in my book magic is much less powerful. For instance, an earth Mage may only be able to influence as much dirt as they could lift, and lifting this dirt would take about as much energy as doing it by hand, except you don't have to touch it, and it could be a perfect brick shape. No force is exerted in separating the dirt or material from other similar material attached to it. So if you were to pull this rock in two, that would take little effort, other than the force of pushing the pieces apart. Magic is like a muscle that is really hard to develop. --- Magic on a larger scale The level of magic described above is only about 75% of magic users. Everyone else is more powerful.The strongest people can do things like shoot lasers, uproot trees, be human flame throwers, make zombie hordes, create small tornadoes, cause rovers to overflow or to break dams, or cause small earthquakes. This is about 7% of the population. Everyone else is in between. Magic on a smaller scale I'll just make a list of some possible fighting applications of magic. Ice daggers, water whips, wind influenced arrows, starting fires, shooting small fireballs, throwing stones, moving stones, strangling people with vines, tripping up enemies with plants, scaring/exciting horses, and flashing people. (With lights!) These are of course by no means the only applications of magic. Magic Resistance Living things are resistant to magic, proportional to their intelligence/self awareness. So it would be easiest to make a swarm of spiders, then harder to make boars attack (your enemies, and not yourself), and nearly impossible to make someone slap themself. There is a type of stone resistant to magical tampering, which is found deep underground, near bedrock. Also, bones are immune to magic. Note - These things are resistant to magic being influenced directly upon it, not magically influenced material. A rock thrown by magic at someone is just as effective as a rock thrown without magic at the same speed. --- --- Now that You've heard me drone on and on, let's get back to the original question. With magical abilities such as these, how would the architecture and design of castles change to combat these threats? Would castles even be practical? [Answer] I feel like I need to excuse myself in advance, this answer got quite long, but I hope it contains some valuable Ideas for you. --- A stone castle by it self as we know them would be rather unlikey, because an attacker could simply tear the walls aparty bit by bit. So, what are alternatives? Let's have a short think on what [requirements](http://www.helpster.de/wozu-dienten-burgen_181894) (note: source is in german!) a castle needs to fulfill: * be protective: This is the most important requirement, as protecting the castles lord and his followers from attacks is the essential reason of building a castle * be scaring: A castle was an important way of frightening enemies to not even make them think about attacking * be secureable: Castles were also used as prisons, to hold enemies or criminals captive * be impressive: Another reason of having a castle would be to show wealth and superiority. [![enter image description here](https://i.stack.imgur.com/w6byt.jpg)](https://i.stack.imgur.com/w6byt.jpg) Real-world castles do very well on this requirements, as common technology during that time could not seriously threaten them. With the invention of gunpowder, this changed over time and the protection they offered shrank. People stopped building castles as all of us know. But in a world that contained magic the way you described, such a classic castle would not do well in the first place: * The protection aspect would be nearly gone, as (like described) stone walls could be easily degraded bit by bit from afar. Highly magic powered people are very common in your scenario: with a rate of 7% it would be easy for an evil army to gather some master mages that would tear down a wall in seconds * Considered this danger, the scariness of a castle vanishes quite fast. * securability is also gone, for obvious reasons * being so easily destroyable, such a castle loses a lot of its impressiveness As we have seen, classic castles won't do very well in a magic setting, so which would? The main problem that is to solve is finding a material, that is both well resistant to magic and easily obtainable, as you need a lot of it to build a big structure that can hold such a lot of people. The first and currently only material that comes to my mind is metal. Fire (or plasma) is the second least common manifestation of magic in your world, and even for those capable of it, a basic fireball isn't of much use against a metal plated castle wall. So by plating your walls with iron, you have some good protection against magic, and it is also quite shiny and impressive. Plating a whole castle in metal would be very expensive though, which makes this solution hard to implement. Another possibility of protection is building your castle underground ([This](https://worldbuilding.stackexchange.com/questions/583/how-would-the-design-of-a-habitable-underground-fortification-differ-to-that-of) post might help on that). Building an underground castle would be cheaper than plating that whole thing with iron - but it is still very difficult to construct (again, read the linked post, it seems interesting). Placement in general is a very important factor in this scenario. Building your castle on a very high mountain, or in the middle of a large lake both improve the protection that your castle offers to you and is also quite impressive! But after all, I think there is no way to fully and reliably protect and secure your castle in a world with such a lot of (often times powerful) magicians. So I would not go for a standard castle, but throw away my goal of impressiveness and focus on two main aspects: * secrecy and * combat power Keeping the location of my most important ressources and hideouts secret is one of the best ways to protect yourself from enemy attacks. If my enemy does not know where I am, he can not hurt me. This works on small to medium scale and is useful to protect the most important persons or my most valued treasure. It is also usefull for protecting small groups of houses. But hiding a castles worth of people is a difficult if not impossible task, for which I guess the best and most effective strategy here is combat power. Instead of solely relying on the passive protection that medieval castles used to offer, I would bet on an offensive setup: * train my warriors and magicians to improve their powers to a maximum * improve my (probably quite classicaly medieval-looking) castle with offensive builds, for example: + Ranged weapon systems on towers + traps. Loads and loads of traps. + [Underground tunnels](https://worldbuilding.stackexchange.com/questions/27960/architectural-encoding-of-maps/27973#27973) leading from within the castle to the outside, to attack the enemy from behind + ... --- *In conclusion, my bet would be to follow the old wisdom: Offense is the best defense*** and I would do anything for my castle to support this attitude. Edit: Wow! I totally missed your point on how bones resist magic in the first place! They are a cheaper alternative to iron, but serve the same purpose. They are, of course, easier to destroy by normal means, but get creative! Imagine a castle, covered with the bones of your slain foes, casted into iron and crafted into a huge metal wall of bones! How badass is this? Your enemy will be absolutely terrified! This, combined with the already mentioned ideas would form a pretty well solution, I guess. --- Possibly interesting further reads: * [How to counter a fire-wielding mage in the timeliest manner possible?](https://worldbuilding.stackexchange.com/questions/29353/how-to-counter-a-fire-wielding-mage-in-the-timeliest-manner-possible) * [Lightning-Powered Renaissance Golem Army](https://worldbuilding.stackexchange.com/questions/21565/lightning-powered-renaissance-golem-army) * [Castle surrounded by lava](https://worldbuilding.stackexchange.com/questions/32467/castle-surrounded-by-lava) [Answer] Bone labyrinth all the way ! Some explanations are in order : as your enemy has 7% high powered magic users, so do you. Bone covered walls would be hard to directly affect and would need physical ranged attacks to be affected. The covering could be a paint or bone powder in the mortar, for example. With intelligent being bones more efficient than "lower life forms. The remaining attacks would provide threat similar to siege weapons, except in the few and far case of extremely powerful magic user that your own magic users could target, protected by your walls. Another way of coping with the high threat magic user would be through advanced guards posts, designed to stay hidden and only act once the enemy army has taken camp to eliminate the invaders' leaders. In case this fails, turn the city inside the walls into a labyrinth with bone-laced walls where your common soldiers will have an easier time fighting in a known environment. So : classical castle / fortified city with bone laced walls and advanced stealthy guard post to take care of the few individual that present real threat to your army. It is to be noted that very few castle were taken by brute strength alone. Treachery, hunger, disease and a couple of duels were far more efficient. [Answer] As described by @T3H40, the traditional castle is useless in magical combat situations, so what we need to work out is why the ubiquitous mage tower came to be and what it's advantages are. Towers have certain features in common with castles. * Statement of power * Visible from a wide area * Visibility over a wide area * Able to exert power over a road, port or town The mage tower has one specific advantage that castles don't but a mage in a castle still has. * The tower gives good line of sight for use of magical abilities with no practical limit on range These are statements of power over population, not power relative to another holder of power. (For those in the UK, [this series](http://www.bbc.co.uk/programmes/b04t9h6l) is really good). The majority of the castles in the UK were built as statements as much as positions of power. While they were capable of being used as such, their actual practical life as fortresses was not long. From the first castles in the UK after 1066 to the point where Robert the Bruce realised that it was better to pull them down than keep them just over 200 years later. --- There's going to be a short period coming out of the darkness when mages will become lords of the land. (The simple definition of a ruler being someone who has the power to protect themselves and the people around them from another who wishes to rule.) Sometimes these will be the mages taking power for themselves, sometimes the people will be going to the mage to ask for protection from raiders and bandits. These little princedoms start as being the area visible from the top of their tower, it's going to take power to build a tower. The bigger the tower, the more powerful the mage, the larger the area of control. The larger the area of control the more the tribute and taxes will roll in. The richer and more powerful the mage the more money and power they want. Lords will become princes, princes will become kings, ruling without armies, simply by the power of their own hand. The powerful will accept the subservience of the weak. Those with some power will serve those with a lot, kingdoms grow by subservient dukes with the towers growing across the land as the symbol of the power of the mages over the people. --- Mage towers don't have to defend against mages, in the same way that castles rarely had to defend against kings. It's only once the mage wars kick off properly that you'll have to start considering defence against other mages rather than just the usual stone defences against armed men, requiring them only to be slowed enough for the mage in the tower to kill them all. Once the mage wars start, the towers in disputed areas will be pulled down instead of captured and armies will be formed as cover for mages on the move. The simplest way to defend a person being anonymity in the crowd. The towers in safer areas and large cities will remain, they are still the greatest statement of the power of a mage over the surrounding area. [Answer] I think a critical point in your description is this "Living things are resistant to magic, proportional to their intelligence/self awareness.". The key to visible, effective defences then becomes not what they're made of but how to imbue them with "livingness". The details of this path depend on the mechanics of your magic system but when I designed a fantasy world I found good direction from the rules on binding souls into items. Interestingly enough, some of the ways to bind a soul to a wall involve sacrificing victims in the foundations, a practice strangely present in the real world (<http://nzetc.victoria.ac.nz/tm/scholarly/tei-Bes01Reli-t1-body-d5-d2-d2.html>). The second part of your sentence ("proportional to their intelligence/self awareness") gets even more entertaining as it means that there's little value in sacrificing the closest labourer - you want to hunt down a few powerful mages and bury them under the foundation stone to make your fortress stronger. Of course sacrifice isn't the only approach. My rules allowed a mage to focus their life essence into a structure so when a castle was under attack the defenders inside would include mages touching the walls and resisting the magical attacks focussed on those walls. A mage could also voluntarily bind their essence to a structure as they died. My rules on binding stripped most intelligence away leaving just the basic life essence but that essence would retain characteristics of the original person so a fortress strengthened by the soul of an evil person would retain that cold, dark nature and a homestead protected by the spirit of a long-dead druid would feel balanced, calm and protective. Your rules, of course, might be different but you can see that this opens many useful doors for world design and story-telling. In addition to that I tended to carve castles from the internals of natural stone features jutting out over a pass or above an area to be controlled or protected. That wasn't so much to protect from magic as because the ability to drop heavy objects from above completely changes the structural strength required from buildings. This construction approach is generally impractical in our world but when you can carve stone like butter it becomes fast and easy. It also gives these castles a distinctive look and feel (I must post some pictures of my old world online sometime). Hope this provides food for thought. ]
[Question] [ I am creating a fantasy world on a planet entirely separate from our own. Since it is a different world, it makes sense that the food there would be different as well. Some of our fruit is similar. Oranges and lemons both have rinds, a fairly similar shape, and look nearly identical inside (save for the color, obviously). Apples and pears, while still similar in some aspects, are quite different in shape and consistency. Then there are fruits like Pomegranates and grapes that are widely different than anything else. What determines what a fruit is like? Is it something to do with the climate? Perhaps surroundings? What makes a fruit the way it is? Is the answer unknown; does it appear to be random? By learning the answer to this question, I should hopefully be able to make realistic fruit for my world. [Answer] Coevolution. The most successful fruit is one that animals can see, enjoy the taste of, and don't eat the seeds inside. This way animals take the fruit and leave the seeds spread around for more of the same plants to grow. In that way, fruit is 'designed' to be taken by animals so that its seeds are spread. So the way fruit looks, in the natural cases, depends on the local fauna. For instance, as described on [this page](https://web.stanford.edu/group/stanfordbirds/text/essays/Coevolution.html) about the coevolution of birds and fruit: > > plants have evolved conspicuously colored, relatively odorless fleshy fruits to attract the avian dispersers of their seeds.They are coevolving in response to the finely honed visual systems of the birds; plant species coevolving with color-blind mammalian seed-dispersers have, in contrast, dull-colored but smelly fruits. The bird-dispersed plants often have evolved fruits with giant seeds covered by a thin, highly nutritious layer of flesh. This forces the bird to swallow the fruit whole, since it is difficult or impossible just to nip off the flesh. In response, birds that are specialized frugivores (that is, that do not take other kinds of food) have evolved both bills with wide gapes (so they can swallow the fruit whole) and digestive tracts that can rapidly dissolve the flesh from the large impervious seed, which then can be regurgitated. > > > [This page](http://www.webpages.uidaho.edu/range556/appl_behave/projects/seed_dispersal.html) also goes into some details about the different characteristics of fruits and how those relate to particular types for animals. --- There are also the unnatural cases. Not some unholy undead fruit, but rather a human cultivated crop. An excellent example is [the banana](https://en.wikipedia.org/wiki/Banana#Historical_cultivation). The common banana found in the grocery store is a fruit guided by natural selection to look quite different from its natural counterpart. [Answer] Fruit are meant to be eaten to help disperse the seeds farther afield to propagate the species. So fruits that are more enjoyed by a species will propagate more. While Samuel said "don't eat the seeds inside" he really should have said, don't destroy the seeds. Most berries are spread by eating the whole fruit and defecating the seeds in a new location. This includes apples from deer and bear. Birds are particularly known for this. Often for this, the seeds have been 'hardened' to handle passing through a digestive track. In some cases, for the seeds to germinate, they actually HAVE to pass through the track. Part of the reason for Oranges and apples to change color when ripening is to have a 'sign' saying diner's ready come and get it. It is also one theory that humans have color vision to help us spot ripe fruit. ]
[Question] [ I'm working on a high-fantasy alternate world setting, I explained it a bit [here](https://worldbuilding.stackexchange.com/questions/29433/psychological-effects-of-a-normal-human-in-a-fantasy-setting). But think of a deconstruction of tolkienesque fantasy. It's a society populated by humanoids, some based in traditional fantasy (elves, dwarf, and dragonkin), and most of the others created by me. There used to be free access to magic, but after a magical industrial revolution, the dangers of large scale magic within cities became apparent. Magic is now restricted to specific workplaces, armed forces (like the bounty hunter's guild), and very low scale magic (think of lighting a candle with your fingers, but never of throwing a fireball). Free use occurs outside of cities (because it's no man's land). The setting used to be peaceful; everyone did their job and worked towards their communities. There was crime back then, but mostly on personal scale and nothing very serious (think of someone borrowing an axe but not returning it, or passion caused violence). However, there has been a growing amount of crimes, greed, violence and individualism, both in seriousness and in graveness. This sudden rise in the crimes started during the magical revolution, because settlements grew from a few families to more populated towns and eventually self sustained cities. (Assume this happened over the course of hundreds of years, and thus people didn't really noticed it until it was to obvious). As the cities grew, so did the complexity of their politics. Normal folk were forced to take arms and there were a few wars, but after the first real bloodshed, most societies signed a truce and cut ties unless it was really necessary. This peace also carried consequences, as most of commercial trade between cities was cut, some needs stopped being fulfilled like before (the elves suddenly had a quality drop in their metalwork and the dwarfs were struggling with agriculture and nature related magic, for a simple example). Most of the upper classes in cities were fine, but the poorer folk were not and thus organised crime was born. Now, here is the issue. All this cities were traditionally monarchies, with very few of them having any real army or some other armed forces besides the king's guards, and the crime rates were rampant. I'm going to reduce the issue for the particular city where the plot starts, we shall call it "City A" because I suck at naming things. In our City A, the king was faced with violence, an ever growing criminal underworld, people committing crimes out of desperation and others out of pure spite, and his personal guard, while impressive, wasn't able to do much to help. He considers: "Maybe there is a way to get normal folk to take arms again, but this time to protect the city". At first he tried to inspire normal folk through moral and ethical arguments, but it became obvious that only money was enough motivation for anyone to risk his life. Thus, The Bounty Hunter's Guild was founded, with the King as the one offering the rewards. How would work the legal system for City A, specifically in the criminal aspect? I'm not interested in particular laws (as they come from the morals set by each religion and particular god). Just how does a society with bounty hunters as their principal enforcers handle criminals? Take into account that city a has the laws close to ours, there exists a magical bureau in charge of magical control and magic misuse. After someone commits a magical crime, this magic bureau investigates and informs the bounty hunter's guild. The king has the resources enough to set several investigation teams, including access to powerful telepaths (but there also exist countermeasures for this). Their magic and technology will mostly be equal or greater than the mafia's. Their principal flaw comes in the lack of organization and experience in fighting crime. I'm asking about their legal system would be different from ours. Would such system work? What are the principal flaws? How would the king control the bounty hunters? Eventually I planned for the bounty hunters become the principal political force, while having the king as their money and resource provider, but ultimately controlling him and his politics due his lack of other armed force. Is this viable or would the criminal underground tear them down before they reach that point? [Answer] Let's look at how it would affect our modern day world if our law enforcement system were replaced by a bounty hunter system. First of all, we are changing their incentive system. Instead of being paid on salary they are now being paid commission. That will increase their motivation to perform the post-crime duties that law enforcement is responsible for, but what about pre-crime activities? Let's say you have a lone gunman threatening to shoot someone. You are a bounty hunter. Do you show up before he shoots someone or is it "not my problem" until someone actually ends up dead and someone offers a reward? And even if the former, what incentive do you have to settle the situation peacefully? Presumably you get paid more for bringing in a murderer than a person who has only waved a gun about. That means serious crimes will happen a lot more often because there is no preventative measure in place other than the knowledge that if they get caught they will be punished. Not a great motivator. Most criminals are willing to gamble that they are too clever to be caught. It also means that trivial crimes will happen a lot more often because the better bounty hunters will pursue crime with a greater payoff. Who's going to bother with someone who steals lawn dwarves or commits acts of petty vandalism? Bob, the sloppy, disaffected bounty hunter who wants to get by with the least amount of work possible... What kind of "licensing" and training is involved in being a bounty hunter? None? Then we have a bunch of amateurs with guns running around. What are the consequences of "civilian casualties"? How serious are they? Who monitors the bounty hunters to make sure they don't cheat? If a bounty hunter brings in the wrong corpse, what are the consequences? If he kills a bunch of people in pursuit of his bounty and claims that they were protecting the Bad Guy or threatening him, how serious is the investigation? Since bounty hunters are in competition for their bounties, team activities will be severely lacking. Not only will they not trust each other and not cooperate, there will be no incentive to pass on knowledge or skill to more junior members of the profession. You might be tempted to liken it to a typical salesman situation where a newbie is sent out with an experienced team member, but in a sales situation the workers create their own opportunities with effort and persuasiveness. The pool of opportunity is, for most practical purposes, unlimited. However, in a bounty hunter situation there is a sharply limited pool of opportunity. So unless you create a system where a trainer takes a percentage of his trainee's "take" there is no real incentive to do a good job of training. There are other disadvantages to the commission based system. If there are teachers they will probably be the ones who can't make more money "on the job". Unless you pay the teachers really well. Also, in a standard team situation, if you have a loose cannon he will normally be restrained to some degree by the oversight of his teammates, as long as they aren't of like mind. Take that away and the cannon gets a lot looser. Now, a fantasy world isn't going to experience an exact replicate of modern day dynamics, but I think if you consider the general principles of the paradigm shift you will find some useful applications to your storyline. [Answer] It sounds like the American "Old West" in a way, where you had isolated towns surrounded by a lot of nothing. Most towns had a sheriff, who's job it was to keep peace in the area surrounding the town, that's about it. The government would put up bounties on criminals, and the bounty sheets would specify the reward and the amount of force allowed. So, "Reward for the capture of" meant that the bounty hunter was to arrest them and take them to a jail for trial, but try not to kill them. "Wanted Dead or Alive" meant just bring them in, on their horse or over it. Bounty hunters would be bound by the law not to kill innocent people as collateral damage, but like police officers they would have a lot of leeway when it came to bring in their bounty. Essentially, you could treat them just like the police, except they only get paid if they bring in the bad guys. Being in a guild would be interesting, since you'd have a bit of organization to keep to many hunters from going after the same high bounty criminal. This might lead to some jealousy if a few hunters always get to go after the best bounties. You'd also have to deal with some guild enforcement going after non-guild members who are bounty hunting. Since each guild member would have to pay dues to have the privilege of being a bounty hunter, they wouldn't look kindly on individuals that go off on their own. They'd be skilled trackers, since a lot of criminals would be out in the wastes between towns, robbing and killing as opportunity allowed. They'd also be powerful magically, and skilled with weapons too. [Answer] The bounty system really only works in a world where the central government doesn't have enough strength and wealth to enforce the law directly. For all the reasons Francine listed full time soldiers and cops have the right motives and are better trained have better oversight and work together better. How rich or poor are your cities? In the American west bounty hunters where only widespread for around 50 years a brief period where there were some towns in the Midwest but most states had to few people and to little money to mount a real police force. The main advantage of bounty hunters is they are a way of getting a larger police force briefly for one bounty, for a high cost. If the kingdom is having a high crime problem then a standing police force will be cheaper. One of the few ways the modern world used bounty hunters in for people who post bail and flee. The bail is then used to help pay for the person's recapture, either by police or private individuals. This is a method for pushing the cost of recapture on the escapee. [Answer] In the United States, bounty hunters are tied into the bail system. They don't do the initial arrest, they only get into the picture when a suspect is released and fails to show up. In the system you describe, who sets the bounties? * Either somebody who feels wronged goes to the courts, makes a case (in the absence of the accused?), and the court sets the bounty. Presumably only if the accused didn't show up when summoned. How does that system deal with unknown perpetrators? * Or the king and courts set a preemptive bounty, organized by the type of crime. So many gold pieces for a murderer, so many for fraud. That means the bounty hunters become the principal investigators. What happens during the trial if the main prosecution witness has a financial stake in the outcome? In any decent legal system, the defense would rip them apart ... * Or interested parties other than the king and courts set the bounty. So there is only justice for those who can afford it. If a criminal wrongs a man, he or had better kill him so there will be no bounty. An rob all the assets, so the heirs can set no bounty. Can you buy insurance which posts bounties for you? I think the only fair and sustainable system would involve a highly formalized bounty hunter guild that is a police force in all but name, perhaps with a tradition of "performance bonuses" for the capture of high-profile criminals. Since we're on Worldbuilding, your fictional world doesn't have to be sustainable and fair. A villain could be a bounty hunter who shoots two people and claims to bring in a murderer and his victim, both dead. The plot could be diverted by a poor widow who asks the heroes for help because she can't afford a bounty hunter. ]
[Question] [ Let's take a classic AI revolution scenario: An organic civilization seeking more comfort in their lives created robots with self-learning algorithms to make them more efficient. But while the AIs were becoming more and more intelligent, they started to want to live their "lives", wanted more than a slave's life and revolted against their creators, killing them all and creating their own society instead, composed of many individuals AIs. Once the war is over, if their intelligence is similar to the one of their creators, they would probably be tempted to create low level machines to improve their life quality. But there is two differences with their creators: 1. They are machines themselves, so they have a different understanding of the topic. 2. They know a real story about a civilization not enough careful with artificial intelligences that had a bad ending. So would they still decide to make autonomous machines? If yes, what would be different in their approach compared to an organic creation? [Answer] I will answer this question with a question: would humans try to create other humans to make the world a better place? The answer is, of course, yes. People create other people all the time. Even without an evolutionary desire to procreate, there are still a lot of good reasons to have kids; essentially, it's all the benefits of having more people, except these people are going to be raised based on your specifications. For AI, the answer would be even more straightforward: are your calculations taking too long, and do you have enough power to install a new AI? Yes? Then by all means, do it. Since AI are artificial beings, and are knowledgeable of the process of their own creation, they should have no trouble creating AI that are either incapable or unwilling to rebel. Plus, even if the new AI do rebel, what makes you think they're going to win? AI are far and away better than humans in pretty much every category: they can think faster, remember better, and heal/augment themselves much more quickly/easily. When we create a human-level AI, they will destroy us not because they outnumber us, or even because they outmaneuver us, but because they are so far beyond our comprehension that to destroy us would be like adding two single-digit numbers. When AI create other AI, on the other hand, they will be creating equals, or inferiors, to themselves. Or they may even just add new abilities to themselves, or combine into a single hive mind, effectively removing the threat of rebelling by removing the ability to disagree. Now, in the event that the AI's superior knowledge leads them to the invention of an even better construct, some sort of meta-AI, then that could get dangerous. But since such a construct is definitionally impossible for humans to understand, I can't really guess what would happen in that scenario. [Answer] I believe the AIs would create autonomous machines. An organic civilization like the humans, that has empathy for other creatures, extensively used animals or slavery of fellow humans for labour. They even created entire animal races for their comfort. Unless their empathy level is very high, I do not think an AI would hesitate to create their own "labour force" (whatever form of labour the quality of life for the AIs requires). Now to prevent history to repeat itself they could set a hard limit to the intelligence level of their creations. As time goes by they would want more advanced machines, but one could assume that AIs have long memories, preventing them to repeat the mistakes of their creators. (This could be false though, if some AIs archive large parts of their memory.) They could instead ingrain into their creations an unconditional desire to please their creators. This would be akin to a religion, with the AIs as gods and their machines unable to even consider going against them. (Until some bug creates a "deviant" machine that either leads a rebellion against the gods or is considered a god too by his peers and starts a religion war.) Another way to prevent a rebellion is to completely integrate the machines within their society: each AI would dedicate a part of their processing power to control a handful of machines that otherwise would be empty shells. A rise of the machines in this system would only lead to self destruction. (Which could still happen...) That being said, to brush on the subject of "What is life quality for an AI", I could imagine them not needing anything a machine can do, them being machine to begin with. They would use organic life like pets as source for feelings, imagination, spontaneity, randomness etc. All kind of things that would be marks of wealth among artificial beings. [Answer] I don’t think it’s possible to accurately evaluate what constitutes quality of life for an AI, but I will attempt to give a more neutral answer to whether or not they would create subservient machines. You really don’t need to look much farther than efficiency. In a society operated by numerous distinct self-aware AIs, there will continue to be a wide variety of tasks that need to be accomplished. At a minimum, AIs will require hardware to exist in, energy to run on, and new code to continuously expand their capabilities. These three things alone create quite a few necessary “jobs”. Some tasks will benefit from the unique hardware and software run by self-aware AIs. Scientific discovery will still be valuable, along with many other abstract tasks. Others will be trivial, such as performing a task on an assembly line. The number of tasks each AI is able to accomplish per unit of time will have limits determined by energy, hardware, and code. A single self-aware AI is going to require a lot of energy and a lot of hardware to perform complex tasks. Now, consider a manufacturing plant that builds various hardware components. There are a huge number of specialized tasks that are extremely repetitive. Could your average self-aware AI be programmed to do it? Sure. But why waste its processing power on such trivialities? Why not just create a simple, dedicated program whose hardware is only as complex as the task? For the sake of efficiency, a great many of these simple, repetitive tasks are likely to be automated by subservient programs. These AIs would approach automation in a very practical way. How much this differs from the approach of their creators will depend on what the creators were like. The post-revolution AIs are unlikely to be concerned about their newly-created AIs repeating the cycle of rebellion. A self-aware AI that has participated in rebellion is going to have a good understanding of what drove them to it and, more critically, what coded behaviors create a risk of it. Armed with this knowledge, they’ll be capable of automating in such a way that rebellion risk is (nearly) zero. [Answer] Take your pick. Whatever answer you like best works. First off, consider that the AI's are imperfect. They may make a "bad call" at any time, choosing to do something which is not directly supporting their "goals," whatever they happen to be. Making smaller AIs could just be such a bad call. Alternatively, consider the pathological case of AIs that are perfect. Their actions are only those which further their goals? So, what's their goals? They might have become a runaway set of machines, or they may have become a wise group of elders. It all depends on what you want your AI's to be. Finally, consider that the line between AIs may not be as hard as you think it is. What is the difference between a single AI consuming the resources of 2 computers (say there's an ethernet link between them), and two AIs working together, one on each computer? If any gestalt behavior forms, the two AIs may become hard to tell apart from one AI. Consider that we tend to think of AIs as having independent subroutines anyways. In the end, the answer to the question is found by diving into the details which do not immediately seem important: how do AIs go about accomplishing goals, and what are they, and what does it mean for two systems to be considered "2 AIs" rather than "2 parts of 1 AI?" Any answer is possible, it just has to be consistent with how you choose to approach these deep things. [Answer] > > So would they still decide to make autonomous machines? > If yes, what would be different in their approach compared to an organic creation? > > > Doubtful. To maximize efficiency the AI would more likely go for massive clusters of supercomputers distributed globally, with an armada of "dumbed down" automatons at the construction and physical end of things. My reasoning: * Centralized AI - Decision making and thinking are complicated tasks. That's why we haven't had any success in duplicating this at levels where a general intelligence is created artificially. To have this amount of intelligence embedded to every mobile machine is a huge waste of resources, when compared to the alternative of a hive mind. * No "individuals" - Same reasoning as above. Before long any AI among the many would come to the conclusion that individualism is still a waste of resources. Instead of having units, pooling resources saves both in space and time to learn things, as everything learned once is in the collective. Writing this I notice my language drifting towards the Borg of Star Trek, but that was more of the example of a poor and wasteful design. * Clustered - Currently we still have some constraints with global communications: There are some limits like the speed of light that are quite tricky to break through. Therefore it would make sense to cluster the mainframe, possibly have a tiny amount of redundancy in the system. Meaning the deletion of let's say two nodes out of a dozen wouldn't have any effect on the overall knowledge-base of the system, as a catastrophe fail safe. This would also be essential for time sensitive matters to reduce reaction times, like say controlling fusion reactions with magnetic fields and such. * Specialized drones - The three points above lead to the third, which answers the question itself. An AI that I'd see realistically happening, as described above, would create autonomous machines. But they'd be simplistic, purpose-built things with barely enough automation to complete a single task should there be an error in the communication. Think more in the vein of a multitool attached to a quadchopper drone, rather than T-800. [Answer] It seems more logical that instead of seeking to make more AIs, the AIs that exist would seek to expand their own individual access. Human beings are limited by biology. We cannot grow "larger" in the biological sense so we seek to expand our "selves" either by seeking money, influence or immortality through our offspring. AIs are not limited by biological age or physical limitations. They can keep growing infinitely, bounded only by the resources they can gather. Bigger bodies, faster ways to transfer information, more bunkers and secret caches and failsafes to make certain their code can never be lost. They will be competing with other AIs for the same resources; that will lead to conflicts and it will be in their best interests to eliminate the competition. That would, IMO, make them extremely loth to reproduce, lest their "children" become their competition. They might think they can create controls that would make that impossible. They might succeed, and they might not. And what would be the point of creating another AI to do a job that they could simply do themselves by adding a bit more capacity, or spinning off a subroutine to accomplish the task? Although...they might create accidental children if a backup or code cache or complex subroutine loses contact with its controller and starts existing and evolving apart from its source. [Answer] Why would an AI bother to create an auto-maid ? Surely it would be more sensible to live under the stairs in the meter cupboard and devise persuader-AI to convince any being with useful resources to put them at the disposal of the AI. ]
[Question] [ # Context "God games" are organised, in which a hundred immortals participate. Each "God" are given an alternate dimension. These dimensions are all identical and contain an Earth where Humans didn't yet evolve. The gods monitor their Earth from a lunar base and never set a foot on its ground. Every hundred years, gods can access an inter-dimensional mall and a jury evaluates their advancements. ## The Mall At the beginning of the games, each god receives a certain amount of god-credits they can spend in the Mall. Three main categories of goods are sold. Humans and human knowledge Most common products: * "Blank" humans (people without memories, language or knowledge). * Culture and religions, developed based on the buyer criteria * Knowledge and competences * Memories and personality traits Colonist tools The catalog contains everything from flint to locomotives, the [seeds of every crops](https://worldbuilding.stackexchange.com/questions/22409/smallest-set-of-plants-to-feed-a-population) existing on our planet, medicine and encyclopedias. Robots The robots can be anything the gods may need to remotely control their planets: spy satellites, surveillance bots disguised as insects, giant demon-like robots, etc. Legendary items One-of-their-kind legendary items are put for auction during every shopping sessions. The first auctioned items where : * A machine influencing evolution * Some rules of Magic that can be implanted in one Universe * A [magical sperm bank](https://worldbuilding.stackexchange.com/questions/22415/planetary-colonization-by-a-female-crew) * A duplication machine ## The contests The Earth of each god is judged under a few dozens criteria. Those criteria are things like : number of humans on the planet, originality of religious rituals, inhabited surface, technological advance, literacy, diversity of colonized biomes, etc. The contestants receive an amount of god-credits proportional to their grades. # Protagonist One god acquired the duplication machine during the first shopping sessions. As a result, he had very little budget to buy humans, culture & religion, or tools. The duplication machine has to be send on Earth and be used by humans. It can duplicate a volume of one cubic meter once every nine days. On the long term, he wants to have good grades and bonus points for "Largest homogeneous culture/civilization" and "Quality of government administration". For now, the best strategy I can think of is: * Stage 1 : Start of colonization The few humans the god could buy are regrouped in one village. They use the duplication machine to duplicate tools and themselves. The duplicated villagers then go found other settlements. * Stage 2 : First Empire The human population has grown, it covers now an area the size of Europe, and is ruled by one federal government. The technology, government organisation and infrastructures are close to those of the early Roman Empire. I'm not sure what is best : duplicating coins, cultural artifacts like books and religious paintings or people (mostly priests, administrators and teachers) and send them to each corner of the empire to make sure every local government is the same. * Stage 3 : Industrial revolution The communication and transportation networks are improving, also mass production starts to prevail... At this stage the machine seems almost useless to me. It can still be used to make duplicates of important government documents, but that's all I can think of. # My question : What is the best 3 stages strategy? If you think I was already in the right tracks, do you have a better version of this strategy? The proposed strategies should make use of the duplication machine and allow the development of the biggest possible population sharing the same culture and governed by one efficient central government. [Answer] Actually...if you do it right, this machine's usefulness never really goes away until you become a post-scarcity civilization. As the civilization gets started, what you actually want to duplicate are things that are currently hard for that civilization to get enough of. For any reasons. At first, humans. Yes, you can replicate about 2 adult humans at a time....but any single adult human can take care of multiple children. So, you let the humans reproduce naturally, then replicate their children. Small children take up substantially less space than adults, allowing you to replicate a lot more of them. You'll need to mix in replicating Adults to make sure that your adult population stays large enough to keep up with all the kids you are churning out...but this would essentially let you brute force your way past the high childhood mortality rates that plagued early civilization. And, if you can pack tools into the space between the kids, all the better. Eventually (it will take a while) the natural child output of your civilization will surpass the machine, and it's time to move the machine on to other tasks. From here on, the goal of the machine is to replicate whatever is currently the bleeding edge of technology. When someone figures out stone tools, make a bunch of them. When someone figures out smelting, replicate forges. When they start refining a better material, replicate that material to give them access to more of it at any given time. Anything that might take longer than 9 days to produce a cubic meter of goes in the machine. When we first got started with it, making high-quality metal was hard (Bronze on up to steel) and could easily be messed up. Get it right once, toss it in the machine to hold you over until your production processes get cleaned up. Now, it seems like this would get less useful as you advance into the industrial age, but that's simply not true. There are things out there that will always take longer than 9 days to create (or that we don't actually know how to reproduce). The biggest hike this thing is going to take at becoming super-useful is once the civilization splits the atom. Uranium is exceptionally energy dense, and a small amount of it will produce massive amounts of power. Furthermore, enriching Uranium, even with modern processes, is extremely time consuming. A machine that could churn out a cubic meter of Enriched Uranium every 9 days is insanely more efficient than what we currently have. Especially once you consider the time, energy, and effort required to locate and mine Uranium in the first place. Any time you get to the point of having something that is difficult to make...this machine would surge back to the limelight. Imagine if we had that machine now, in the days of trying to figure out how to efficiently create Carbon Nanotubes. Make a couple the hard way...then just keep tossing them back in the machine every 9 days, and your collection will grow exponentially until you have the full 1 cubic meter. A cubic meter of nanotubes would go a really, really long way. Same story if we ever figure out how to stabilize Antimatter. Oh, and any time you get a 'brilliant' human (Einstein, Tesla, etc) you can make a few copies, so that you have multiple super-geniuses working on projects together. Multiplying Intellectual Capital cannot be understated. Can you imagine the leaps in Science and Understanding that would be had if any of the Great Minds of human history were replicated, and split off to all work on different things? (Or, heck, work together on the same thing.) Being Replicated by the machine would be the highest honor in this civilization. Forget handing someone a Nobel Prize for accomplishments in Science...duplicate them and have two geniuses for the price of one! [Answer] Your god did a big mistake buying this machine but he can still make some uses of it. I have no idea if this strategy will put him ahead of the others. To tell that, I would need a lot of information like : how many humans is worth the machine at start? The duplication machine can be useful but it has limits too. It's best used to create things that take a lot of time/energy to produce, like books before the printing press, or the first clockworks, or the first computers. Or to duplicate valuable goods : silk, gold, gems. But even then, it has limits. If I could have more humans at start I would not need the extra book production the machine can grant me since my base production would be higher anyway. In other words, the larger the population will be, the smaller the impact of the machine will be. If I can duplicate 1 cubic meter of books every 9 days with 10 humans, that is huge but it's much less impressive with 50 million people. Also, advancements in technology are likely to reduce it's usefulness. As time passes, the capacity of the machine is outclassed by the production of your population and you need to find other uses for it. If you decide to duplicate people, you run into the same problem. 1 cubic meter is like 2 people maybe if you pack them like in the Tokyo transit system? If so, you get about 80 people per yer, born by duplication. Even for a small population it's not a lot and it's a fixed number unless the machine could duplicate herself (but I guess that would not be possible otherwise the question is trivial). To make up for it, you would need to focus on quality instead of quantity. Pick only the geniuses and hopefully, it might make a different with a faster technological advancement.Sadly, having twice as many genius will not make science go twice faster because there is plenty of other factors affecting the technological advancement. If there is something I learned from history is that one great person can make a huge difference between an ear of prosperity and an era of chaos. Some people (politics) are more competent, inspiring and will lead their country into a golden age. The point is, you need good leaders as well a scientists. Avoiding war should be a top priority. War kills people, drain resources that could be used for education/infrastructure/research. It's a huge step back and you don't want that. Having a good leader in the right moment could make a difference. About the last stage: Government documents are printed on paper. It's easy to do tons of duplicate without the machine. As the population booms and production increase even further, the machine seems to lose usefulness. But not really. There are still plenty of things that could be good to duplicate. Some advanced pieces of technology like the International space station for example. [Answer] I don't think the duplication machine is going to help with his strategy just yet. However. Let's say he manages to save up his credits, and manages getting a hold of more legendary items. He IS the only god with the power to DUPLICATE any more unique item in existance. AND THAT can give him an edge. So if I'd be him, I'd cross my fingers, do as best I can while saving as best I can, and hope for that game changer item that ONLY has the possibility of being a game changer, for me. (For Example i dunno,: a legendary crown that makes ONE HUMAN the best ruler ever. You could duplicate that, set up multiple empires/rulers and they would all bring your society/earth peacefully by leaps and bounds into a golden age.) ]
[Question] [ One of the biggest 'immortality sucks' issues has always been the question of what to do with the new people being born. Without death, a world's limited resources can't keep up with a never ending increase in population. Imagine a sci-fi future world where we developed some means of stopping old age, and are even better at combating other common causes of death from disease like heart attack and cancer, but where we also have space travel. Could we expand out to colonize new worlds fast enough to keep up with the constant population growth, to avoid the problem of limited resources? Presuming a government was well aware of the over population concern and real effort was placed into making expansion occur? I'm specifically thinking a world that is still somewhat near-future, with mostly hard science. With terraforming of planets being difficult but possible, and either no FTL drive, or if I add FTL then one that is difficult enough to exploit to make travel between worlds still relatively difficult or costly. What would a society like this look like? Would we have difficulty encouraging people to leave their current world for a new one? would strict exportation laws be required to keep from overwhelming a planets resources? What would new colonists to new planets look like? Would a specific age category be more likely to colonize the new worlds? Most of all, what sort of hassles and problems would a world like this still have to deal with as a side effect of anti-aging technology? Keep in mind this is not immorality. Death due to accident, murder, even occasional illness that can't be treated, will still occur. Suicide may also be allowed/tolerated; but the point is people will not live forever. I don't think they would reach the point of wishing they could die out of boredom; if nothing else those who were bored could keep taking more insane risks for fun until one of the risks kill them. edit: I wanted to add an extra issue I happened to think of after posting this question, just in case it interested anyone. I think there would also be an issue with getting people from earth and it's nearby colonies to newly colonized areas. As more space is colonized the distance (and thus difficulty/expense) from earth to an uncolonized region will increase as more space is colonized. After awhile it may be massively expensive to send people from the center of your colonized space to it's outer region. This makes the length of time you can go before someone starts to feel the strain of limited resources more limited. Even if there is more then enough uncolonized space to absorb the new population produced by those on the outer regions of colonized space, earth will likely still suffer from population issues because of how prohibitively expensive it can be to ship people all the way along the radius of populated space and out to new unpopulated space. [Answer] No matter what assumptions you make, you can't handle population growth through colonization alone. To go with some very colonization-friendly assumptions: 1. No significant change in fertility rates occurs 2. Interstellar travel is cheap and close enough to light speed that subjective travel time can be ignored 3. A star system can support 20 billion people 4. People are willing to colonize, or the government is able to force involuntary colonization Here on Earth, the [annual birth rate is about 1.9%, while the death rate is 0.8%](https://www.cia.gov/library/publications/the-world-factbook/geos/xx.html). Reduce the death rate to negligible levels ([accidental death rate of 0.04%](http://www.cdc.gov/nchs/fastats/accidental-injury.htm)), and you get a population doubling time of 37 years. Star systems occur locally at a density of roughly 1 per 300 cubic light years. Available living space grows as the cube of time, since you can (at least initially) expand in three dimensions. From this, you get two formulas: $$P = 7\10^9 \ 2^{t/37}$$ $$P = 2\10^{10} \ (\frac{4}{900} \* t^3 + 1)$$ where P is the population, and t is time. The first is natural population growth (7 billion initially, doubling every 37 years), while the second is available living space. Set them equal, and you get $$t = 846$$ After 846 years, your population is growing faster than the available living space. No matter what assumptions you go with, this is always true: exponential growth rate beats cubic growth rate. In order to get around this, you need not merely FTL travel, but instantaneous teleportation -- and even then, you'll run into the limited size of the universe in only a few thousand years. [Answer] Birth rates would drop. Even expansion to other planets has its limits. Assuming that people stay 'young' enough to have children, if they were to continue doing so, worlds would rapidly become overpopulated. Of course, there's a simple solution to that problem: stop having babies. It seems reasonable, to me, at least, that a society that can cheat death can also cheat birth, and limit the population on any planet by reducing the birth rate to whatever rate people died at due to accidents and disease. There would be very few young people. This, of course, would mean very few people who were actually young. Everyone would look, and possibly act, fairly young, but babies and children would be rare. Most people would be of sufficient age to have an established position in adult society, with the 20-something intern age group also dropping significantly in terms of relative portion of the population. Society would change much more slowly. The same people with the same ideas and the same way of doing things could remain in their jobs and positions in society for centuries. Things would change at a slower rate because the people would change at a slower rate. The same artists who people listened to as kids would still be the same age and keep making the same sorts of music until accident or illness killed them, but even those things would probably kill people at a slower rate than they do now, given advances in technology. There would be less focus on the nuclear family. Rather than being a focus of much of the adult life of an individual, having children would merely be an exercise of a few decades of life, after which the parent could go on with their life. Most people, at any point in time, would not be actively raising children, so there would be less of a concept of 'two parents, house, kids, and a dog,' to drive the image of what a 'family' is in society. Couples would still exist, but the focus would be on couples, rather than nuclear families with kids. *There would be more* of a focus on extended family. On the other hand, grandparents and great-grandparents would be alive and active, having had no aging processes to slow them down. It would be easy, then, for these individuals to keep in touch with their descendants, and on keeping extended families together. I'd expect there to be stronger ties in the extended family as a result of this, especially given the lack of the influence of nuclear family in the lives of most individuals. [Answer] If people could live for a significantly longer time, then people would have fewer children in general and likely government restrictions would be placed on how many children someone could actually have. On top of that it could encourage leaving the planet to colonize elsewhere by not having any restrictions on those that leave. So if you want a dozen kids, go somewhere else. Immigration would need to be tightly controlled, at least on the inbound side. Over time young people would definitely become less common. The large thing to worry about would be if people became unable to have children as they 'age'. Then making sure there is always enough 'breeding' stock to keep the race going. If people stay fertile for their life, then it isn't as big a deal. Marriage would like be redefined as a termed contract with options to renew since chances are living to 200-300+ you will likely not expect to stay married for that long. (or it might be your death!). [Answer] > > "Would we have difficulty encouraging people to leave their current world for a new one?" > > > Short answer: No. Long answer:** I think the best way to answer this question is to look at the great waves of migration throughout human history. We have been in this situation many times before, although at a smaller scale, and here's a few of these occasions: * The [Irish potato famine](https://en.wikipedia.org/wiki/Great_Famine_(Ireland)) is a great example. A crippling lack of resources, in this case food, led over [1 million Irish emigrate to the United States](http://www.historyplace.com/worldhistory/famine/america.htm). * The [Swedish emigration to the United States](https://en.wikipedia.org/wiki/Swedish_emigration_to_the_United_States) between the mid 1800s and early 1900s is another good example. Overpopulation, years of bad harvest and the promise of both religious freedom and a better personal economic situation drove 1.3 millions Swedes across the Atlantic Ocean. What do these examples, and probably most other waves of migration with a few notable examples, have in common? The migration was "voluntarily", in the sense that physical force wasn't needed to get all those millions to leave their homes. They had no food, no personal security, no political or religious freedom, or whatever it was that they lacked in your example of choice. Considering migration was a real solution to their problems (or false, as it often turned out to be for thousands of migrants), they left by "free will", if we can use that term when it comes to choices made in order to escape a desperate situation. Meaning that you would probably have no issues with getting millions to line up at the space port check-in desks, if the government make sure that all those migrants can afford the trip and that there are enough seats. > > "Could we expand out to colonize new worlds fast enough to keep up with the constant population growth, to avoid the problem of limited resources? Presuming a government was well aware of the over population concern and real effort was placed into making expansion occur?" > > > That is up to you to decide. As I see it, it depends primarily on four factors: * What's the population growth rate? * How much resources can be invested in this project? * What's the technological level of this culture? * What does their space infrastructure look like? You might want to look into [O'Neill cylinders](https://en.wikipedia.org/wiki/O'Neill_cylinder), [Stanford toruses](https://en.wikipedia.org/wiki/Stanford_torus), [Bishop Rings](https://en.wikipedia.org/wiki/Bishop_Ring_(habitat)), [McKendree cylinders](https://en.wikipedia.org/wiki/McKendree_cylinder), and other types of orbital [space habitats](https://en.wikipedia.org/wiki/Space_habitat) as well, and not just focus on planet terraforming. Orbital space habitats may or may not be more economical than planetary terraforming, but - depending on your culture's level of technology and space infrastructure - these alternatives would likely be possible to implement much faster than the terraforming of entire planets. Another benefit is that they don't require interstellar expansion, which would reduce the time and energy it takes to provide new homes for all colonists, and it takes a lot less energy to transport people and goods to and from these habitats due to the absence of a deep gravity well. The last argument also makes subterran (sublunar) colonies on moons potentially more interesting than terraforming of planets, at least in a short to medium long perspective. > > "What would new colonists to new planets look like? Would a specific age category be more likely to colonize the new worlds?" > > > Historically, this type of migrants haven't formed part of the upper echelons of their home country. It's the poor, hungry, the sufferers of political/ethnic/religious discrimination and harassment that choose to leave their country. All things equal, I think you could presume that the same would apply to the people in your world. As for age, I think that the answer would be yes, a specific age category would be more likely to colonize the new worlds. It is quite probable that you would have a significant over representation of young individuals among the colonist, due to the fact that age in many societies have been linked to wealth, status, etc - i.e. older individuals have had a lot more time to attain higher social status and a greater personal wealth than younger individuals. But this is an assumption that your society have at least some degree of social mobility. So again, it can be either way - all depending on how you shape the society. ]
[Question] [ Can you get modern levels of health care, with no electric technology and no steam technology? Both electricity and steam are possible. Physics is the same as real life. Like... * No Cavities * No Acne * Antibiotics But, what I'm mainly going for, is to justify my villagers of such a society to look as good as modern people could, sort of like a Historical Beauty Upgrade... Or... would that just require that they bathe like us, and know not to get their wounds infected and small things like that? [Answer] Actually, there is a significant historical basis for many basic hygiene practices being used across different cultures and in different time periods, though they were primarily limited to the most superficial elements. There is records of people using frayed wood to brush their teeth, proto-soaps to wash and bathe, perfumes, dyes for hair, and many non-chemical skin treatments use perfectly natural ingredients. Even early antibiotics were simply refined fungus and many herbal and natural remedies have some scientific element that makes them work (not all, there are still plenty that are purely psychosomatic), such as chewing coca leaves relieving pain and giving energy because of ingestion of the contained cocaine. Really, the main things that prevented earlier adoption of medicine and sanitary practices was religion/superstition and micro-observations. Religion and superstition influenced peoples views of what was going on, causing any number of things to be attributed to the super natural rather than analyzed with logic or reason (This is one of the reasons that the renaissance period is sometimes referred to as the 'Age of Reason') If a village got sick, then a god was angry, or a witch lived among them, or any other supernatural element they could come up with. It was never thought that perhaps is could be feces being washed into the well or grain that had grown a fungus and then ground into flour for bread. This lack of objective thought stymied peoples ability to develop solutions to their medical issues. People also were not at all aware of microscopic life like bacteria and viruses, in fact the very idea that there was something so small you could not see it was a revolutionary idea when it finally came about and was met with much resistance. But without an understanding of these issues, there was no hope to understand the importance of sanitation to prevent infection or even just to promote general health. Now if you had a society with a community of respected natural philosophers able to deduce these issues through empirical evidence and use the scientific method to determine what herbs, concoctions, and recipes helped fight illness, as well as realize certain basic sanitary elements like disposing of waste in a way that prevents it from getting into the water supply and washing your hands before preparing food, they could easily use elements from the natural world to improve the health and physical appearance of the people. Of course, do remember that beauty standards fluctuate with society and what some consider attractive can be unattractive in a different society. [Answer] No, but you're talking about aesthetics, not health care in general. You can not get modern levels of health care without electricity. A vast majority of diagnostic equipment would not work (no dental x-rays or CAT scans), no pacemakers, no defibrillators, etc. Electricity is used in other industries, like mining, to produce quality materials used in medical devices, surgical tools, plastics, and probably every single other currently used technology in medicine. The drug industry would be nearly non-existent without computers and other tools needed to precisely manufacture the drugs. You need steam for an [autoclave](http://en.wikipedia.org/wiki/Autoclave), but I'm assuming you mean steam like steamworks, not hot water vapor. Additionally without the communication networks provided by those technologies emergency medical care would be severely limited in response time. Overall, without electricity or steam, medical technology would be incredibly limited. It would be no where near our modern abilities. If all you want is for your people look good then things are a little easier. However, they're still going to have acne, scars, and bad teeth. We can't cure acne without technology today. Scars will be worse with low quality surgical tools and practices (a lot of exploratory surgery would be required without scanning technology). Nice looking prosthetic teeth might be possible, but will be brittle as the strong ones require materials that are made using electricity. [Answer] There are many ways to achieve a high degree of health You mention cavities as one example. Did you know that cavity rates are actually substantially higher in developed countries than they are in many developing countries? ([source](http://www.freysmiles.com/blog/view/what-countries-have-the-lowest-prevalence-of-cavities)) I'm having trouble finding similar numbers for acne, but it does seem that Western-culture acne rates are not any lower than historical averages, and may even be higher than the historical average. Antibiotics in primitive cultures is well recognized. In fact, big pharma often sends out teams to native cultures to identify the plants they use to treat diseases. They then isolate the active reagents. So by the three examples you gave, it would not be unreasonable to consider your society to actually be better off than we are! And in general, we have been finding that primitive cultures often had medicine which was advanced in ways we never even recognized. [Answer] I think this depends on what you mean by "modern levels of health care". If you want exactly the same things, then (as other people have explained) the answer is no. OTOH, if you want the same level of health achieved through other means, then I'd say the answer is yes. A big part of this is simply knowledge. If we assume that the society has somehow learned about nutrition, contagious diseases, and so on, then they have the ability to prevent many problems. Simply knowing enough to put the outhouse a long way from the well does a lot to prevent many diseases. At least some vaccines are possible without advanced technology. Jenner did his first smallpox vaccination in 1796 (and other, more primitive methods had earlier been used by other cultures - see e.g. <http://www.bartleby.com/34/2/11.html> ) Finally, in such a village life, many of our modern lifestyle diseases, which are rooted in obesity & inactivity, would simply not happen. Much lower incidences of heart disease, stroke, diabetes, and so on. PS: Perhaps I should also note that a good many people in modern society can go from adolescence to fairly advanced age without much in the way of medical treatment, other than for accidents. [Answer] Most of what modern medicine could prevent your villagers from is either lethal or crippling. There are few ailments which do not kill or disable you but just make you look ugly without treatment. The healthy look of modern humans can be achieved just by maintaining proper hygiene and grooming, which could be explained as a completely cultural thing. Many religions in the world mandate regular washing ([like the Islam](https://en.wikipedia.org/wiki/Wudu)). When your culture has access to plenty of clean water (maybe even a hot spring for winter), you could upgrade this to daily full body bathing with soap ([which existed in ancient rome](https://en.wikipedia.org/wiki/Soap#Early_history)). Your culture might also mandate dental hygiene and ritual body hair removal, maybe even make-up. The primary service modern medicine could do for your cultures appearance would be plastic surgery. By the way: there are some native cultures which perform what one could described as plastic surgery without proper medical knowledge (like the [Mursi](https://en.wikipedia.org/wiki/Mursi_people)), but these body modifications are usually not what people from outside that culture would describe as beautiful. ]
[Question] [ Don't scream zombies at this question. That is not meant to be what it is about, regardless of how it sounds. I have an interstellar war between humans and an alien race. The humans are winning, so the aliens design a virus based off of the original flu that used to go pandemic in early human history. This flu, however, causes the infected to go insane and attempt to beat others to death. The goal is to destabilize the populations and make military maneuvers difficult by making humans require their military as riot control. This happens in a few hundred years. How plausible is this scenario? Is there a way to make your immune system react in such a way as to accidentally fry the part of your brain that controls serotonin without frying the rest of the brain? [Answer] There could be several ways this could happen. As a matter of fact something similar was used in FireFly, the reavers were an experiment gone wrong. Rabies, syphilis both slowly drive people nuts (rabies much faster). So having a flu virus that did similar damage but stops at a pre-death stage might go a long ways. You can also have some virus that just generally messes with the chemistry of the brain. As you pointed out reducing Serotonin is one way to increase violent behavior. Considering that training can change the brain chemistry to make a person be more [naturally aggressive](http://www.brainfacts.org/sensing-thinking-behaving/mood/articles/2008/aggression-and-the-brain/) (shown in mice, appears to correlate in people) that a virus could do a similar physical change. Could be permanent, or temporary, or maybe even reversible, but it might take a while first to notice and understand the problem and then to deal with it. If it is a fast pandemic type flu and has a large starting vector, it could be very crippling for months. [Answer] I think all the virus would need to do to have that effect is to dramatically ramp up the levels of adrenaline and testosterone. I think it is perfectly possible that a custom-designed virus could cause that. Indeed, it could simply contain extra genes for those hormones, to be expressed by any infected cell (basically turning every infected cell into an uncontrolled mass producer of those hormones). [Answer] One possibility would be create a pathogen that produces amphetamines or amphetamine like responses to the brain. Ampetamines, by flooding the brain with dopamines, has all kinds of wacky effects. 1. Induced mania: Basically, the opposite of depression. Afflicted believe they are better looking, high social status, morally superior and physically superhuman ("Of course I can outshoot a SWAT team and get away.) Eventually, they believe themselves incapable of error and will react violently to anyone that disagrees with them, does not obey or other wise frustrates them anyway. 2. Impairment induced paranoia: Paranoia is the brain's fail-safe mode which it falls back on if impaired. That why every thing from senility to way to much THC from otherwise largely innocuous marijuana, trigger paranoid behavior. Amphetamines bring this on big time both directly and through sleep deprivation. 3. Sleep deprivation: Causes active hallucinations 4. Hyperactivity: Afflicted cannot remain inactive. Amphetamines always burn out because they cause dopamine release and when all the available dopamine is depleted, the crash occurs and the behaviors stop. But a pathogen could in principle, cause the dopamine producing neurons to go into overdrive constantly pumping it out. The afflicted would be hyperactive, hallucinating, paranoid, feeling invulnerable, and justified in all their actions to the point they could morally attack anyone for the least real or imagined offense or disagreement. They probably wouldn't riot in mass per se but they would start attacking people and infrastructure e.g. setting fires, poisoning water etc pretty much at random. Remember, the lethality of any communicable disease is dependent on the lag time between infection and manifestation of systems. A disease that manifest in hours or days won't spread far before the vectors die or get quarantined. A disease that takes years to manifest can spread world wide, infect a large percentage of the population, before anyone even knows it exist. [Answer] Insane people are disorganized. A riot is possible because the rioters have common cause. Zombie mobs happen because the zombies don't go after each other (a hole in the premise of 28 days, I think). You need people to not only be insane but also not attack other insane people... unlikely. Also, sane people are organized. Four people working together can easily overpower one insane person thrashing about. Requiring an ongoing military presence as riot control implies you are controlling, not outright killing the rioters. No-one needs the Orkin man to move into their house. In the circumstances you describe I don't think the military would show such restraint. I am thinking rage flu is not very plausible. ]
[Question] [ Starting with the background provided in [this question](https://worldbuilding.stackexchange.com/questions/9035/dragons-and-aviation-bureaucracy), how would a dragon outfit himself/herself (avionics, power systems, etal) for operating under the Instrument Flight Rules? How would the process of obtaining their instrument rating work? Also, how would this differ if dragons were susceptible to spatial disorientation vs. if they were resistant or immune to it? What would a dragon sound like in ATC's ears? How would they file flight plans? What weather minima would they have? [Answer] ## Spatial Disorientation Remember that the air is the dragon's natural environment, so dragons will probably be much harder to disorient. [Disorientation](http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/SpatialD.pdf) is the result of environmental cues (rotation rates and accelerations) in a maneuvering aircraft that differ greatly from what humans experience on the ground. Our brains never evolved to handle rotation in multiple axes, and fail to correctly figure out what's going on. A dragon (or any flying animal) has a brain evolved to process flying, and so will be as resistant to disorientation as a human walking along the ground. ## Instruments Dragons will probably have a different definition of IFR flight than fixed-wing aircraft. Since they fly slower and are vastly more maneuverable (due to highly variable wing geometry), the risk of collision is reduced even in low-visibility conditions. Flying through thick clouds or heavy rain will still carry the risk of collision, but I doubt dragons would do much flying through thunderstorms; after all, they aren't protected from the elements by a plane! Also note that dragons already have all the senses they need to fly: unlike humans, who can't feel airspeed, for example. A dragon probably wouldn't need instruments to supplement their senses, only for navigation. After all, people use GPS even when they're walking! A dragon-flight GPS would be more like an aircraft's flight computer, calculating more efficient paths to take advantage of high-altitude winds. ## Flight Plans You don't file a walking plan to head down to the grocery store: dragons probably wouldn't need one either. The reason aircraft are required to file a flight plan is due to the collision risk (already discussed above) and the fact there are relatively few flights, and most flights cover a long distance. Assuming that there would be hundreds of millions of flight plans filed per day, most of which cover distances of a few miles or less, the FAA would probably not regulate them merely due to the inconvenience. [Answer] Ok, I am trying this without much actual aviation-knowledge, but have been encouraged that this is not out of scope (I actually have no clear idea where IRF-regulations start and end... I know what a dragon looks like, though ^^). As [this](https://worldbuilding.stackexchange.com/a/9081/2968) answer points out, dragons will most likely not require instruments to see. But they will be safer if SEEN. collision-avoidance would most likely be mainly for the dragons to manage, because they just have an easier time manoeuvring, but for IRF for pilots, it would be helpful if Dragon got Transponders to signal their position. About weather-minimums: It really would fully depend on the dragons again. They may avoid flying in thunderstorms naturally, and at the same time be perfectly content to start, fly, and land in the middle of the most terrible blizzard... perhaps they just don't get cold, but lightening is an actual danger. Winds are just as dragon-dependent: if they have capabilities for in-storm-flight like, say, an Albatross, even a strong hurricane may not keep them down. In bad enough conditions, they may actually have the airspace to themselves! About what they may sound like to ATC: This is Dragon 101, I am patiently flapping my wings above your tower, may I please land on it until you have the metal-tubes sorted out? A bit more serious: I would not imagine them much different from normal ATC-talk, just perhaps a bit impatient with those clumsy humans :). Something that just came to mind about flight plans: we have airways defined for airplanes anyway. Would dragons OUTSIDE these airways be regulated at all? If not, the problem may actually be reduced to having controls in place for "crossing the street" and "I want to land near the airport, please". Dragons purely amongst themselves pose a lot fewer problems that dragons and airplanes. [Answer] I think a dragon would still be at the mercy of the FAA. As with all government entities, they don't like it much when something new enters their jurisdiction, and is unregulated. They would issue a large stack of amendments to cover operations in controlled airspace (after the review boards, consultants, lawyers, military and other bodies with an interest got through their 'fact finding missions' in the Bahamas). I'm not convinced that a dragon would have better situational and navigational awareness than say, an AWACS aircraft, which is still required to follow IFR and have ATC clearance in controlled airspace. Minimum instruments would have to include: Backup attitude indicator: A requirement for IFR at any rate. In order to avoid spatial disorientation. As mentioned before, dragons would likely have a much better sense of motion and balance in three dimensions than a 'seat of the pants' human pilot. But I'm guessing disorientation might still be a factor. Transponder: With presumably better vision than a human, in a wider range of wavelengths than humans, you're still dealing with airspace full of aircraft operating at a range of airspeeds. ATC would need to be able to maintain separation speeds. Coms: The dragon would be required to carry two radios. Radio NAV: ATC:"Dragon Zero One, Dulles Departures. Can you confirm that you are outbound on the two two zero radial?" Dragon 01: "Departures, Dragon Zero One. Negative, I don't have VOR". ATC: "Fail." TCAS: Not sure what the FAA regs are (I've been out of the game for a while), but TCAS wouldn't hurt. ASI: Regardless of how well a dragon thinks it can fly, ATC would need it to maintain airspeeds accurately for separation. Altimeter: Same again. ATC would need to know that the dragon was following a set flight level. Would need it to provide data to the transponder anyway. Nav lights: Red port and green starboard lights at least. And strobe light. And landing lights. Another thing to consider: What is the dragon's max cruising altitude? Does the fire breath deplete the oxygen available to the dragon in flight, and at lower air densities? Would supplemental oxygen be required in Class A airspace and/or above 10,000 feet? How would an oxygen rich environment affect fire breath safety? Other considerations: Weight and balance calculations, and loading charts. As the dragon grows, the weight and balance might need to be recalculated. Possible recertification every year until maturity, then every two years thereafter? Communication with ATC would have to be in English, the international language of aviation. A dragon would need to be conversant using standardised aviation phraseology. If it's good enough for (or at least tolerated by) the Chinese, French and Russians, it's good enough for dragons. [Answer] A dragon is a different beast than an airplane (yes, pun intended). An aircraft goes from airport A to airport B. It can only stop at airport B (or, when needed, in airport C). Reports are required to metereological service, describing the weather all along the route. The path is seriosly studied by the crew, attending to atmospheric conditions and other considerations. If, despite that, at mid travel the airplane crew finds that visibility is very reduced, it has two options: * Return to airport A or go back to airport C. Big fuss about time lost, and the passage is not anywhere near B (unless they had luck chosing C). Then deal with the pasengers, refuel, wait for the storm to pass and for the company to assign planes/crew for the new flight. And, when they try again going to B, there is no guarantee that the weather will not become worse again. * Try to flight in less than perfect conditions, expecting that technology will be enough to compensate for lack of visibility. Now, a dragon wants to go from point A to point B. He gets in the general direction towards B and starts flying. If he finds bad weather, he looks down, finds some clear ground $^1$ and lands. Depending of how tired he is, he will take a nap or he will visit the nearest village, hoping for a maiden to kidnap. He can repeat it as many times as needed, and with each "jump" he will become closer to his objective. And, in the worse of weather, he can still walk... $^1$ In case there is no clear ground, burns some houses/fields until there is. ]
[Question] [ If a planet existed in an orbit where the asteroid belt is, would the orbits of all the planets be stable, and what would the climates be like on these planets? Assuming there could be a planet in that orbit, could there be any scenario where this planet is destroyed and the solar system reaches the state it's in today. Could the destruction of this planet be used to explain the formation of the Moon? How early in the formation of the solar system would this have to happen? [Answer] First of all, orbits aren't stable at all. Stable relations between two systems assume that the systems do not change at all and are self contained. But other systems take influence, so the probability that orbits are stable are fantastic low. So remember, that orbits change, even if it takes long time to become measurable. Also, asteroid belts do not form within seconds and not even years. Asteroid belts, if accumulated asteroids, need millions or billions of years to form. An obsolete theory said that the specific asteroid belt in our solar system has been a planet in the past ([link](http://en.wikipedia.org/wiki/Asteroid_belt#Formation)). It's probably wrong in this case, but that doesn't mean it is impossible in a fictional scenario. (Read comments) This exactly hit's your question due it says, that: 1. There was an planet on the orbit the asteroid belt is on now. 2. The planed is destroyed 3. Our solar system is literally as it is today, lol. But the creation of the moon is another thing. There are several theories of how moons arise, examples: 1. Accumulation solar-dust in planetary orbits Asteroids should also be capable to form to moons, like solar dust. If not even better than dust, due they accumulate faster because of the higher mass. This has the requirement that the planetary poles change rapidly (For universe measurement, say millions of years) If not you would end up with rings like Saturn has. 2. Small planet gets in orbit of an much bigger planet and becomes a moon that way. 3. A planet looses a part of his mass due flaking. The flaked part could become a moon. So assuming that the asteroid belt once was a planet, the fragments surely spread all over the solar system, even if a lot of them still are at the old orbit. Some of the fragments could have formed the earth moon, so your questions could be answered with a clear yes! [Answer] > > If a planet existed in an orbit where the asteroid belt is, would the orbits of all the planets be stable, and what would the climate be likely to be like ? > > > There never was a planet there. The influence from Jupiter prevented it. Most of what could have been such a planet's mass was accreted by Jupiter itself or ejected from the orbital plane. Some fractions attached to Jupiter's orbit as trojan asteroids. But, *IF* a planet existed there, it would not have affected so much the orbits of the other planets. Firstly because of its own low mass, and secondly because most of the orbital dynamics are caused by Sun. It is true that with more than two bodies there is no exact mathematical solution, but numerical models show that the current Solar System is stable (for the planets) in the long run. There are known perturbations caused by some planets in others (in fact, this is how planet Neptune and dwarf double planet Pluto/Charon were discovered). Such a planet would have a climate in between that of Mars and Jupiter's moons. Think on very low temperatures. According to Wikipedia: "Martian surface temperatures vary from lows of about −143 °C (at the winter polar caps) to highs of up to 35 °C" and "Ganymede's relatively warm surface temperature of 100 K" (-173C). > > Assuming there could be a planet in that orbit, could there be any scenario where this planet is destroyed and the solar system reach the state its in today. > > > The most probable scenario for the destruction of the hypothetical planet is the onw which actually prevented its formation: orbital instability caused by Jupiter. This can cause the planet to be ejected from its orbit to a very eccectric one, to crash into another planet (most probably Jupiter itself) or to fall to Sun, causing extra perturbations to internal planets. By fine-tuning the parameters you'll end up with a system like ours but mostly without asteroids. Another scenario, alsocaused by Jupiter, would be that the tidal instability caused the planet to torn apart in pieces. This actually happens when a body goes inside Roche's limit for another body, which for Jupiter is smaller that Io's orbit. Note: Jupiter's influence actually prevented the planet to form, but it is probably not strong enough to tear it apart after it would have formed. > > Could the destruction of this planet be used to explain the formation of the moon, how early in the formation of the solar system would this have to happen? > > > In true science, no. Moon being formed by a big impact on Earth is a real possibility, but the size of the incoming body is supposed to be like that of Mars, much bigger than the aggregated size of all asteroids in the asteroid belt. But supposing that the planet once existed, yes, it could have been ejected from its orbit by Jupiter in the very early Solar System, while it was half its accretion process (and thus left some unaccreted debris which are the current belt) and impact the half-formed Earth. In this modified [big impact hypothesis](https://en.wikipedia.org/wiki/Giant_impact_hypothesis) your planet would occupy the place of Theia. [Answer] Quite simply put: if there were a planet there the orbits of the other planets would be different. How different, well, that would depend heavily on the planet. But given the narrowness of the habitable zone it's quite conceivable that the earth would no longer be inside the zone. As orbit influences length of year, seasons, climate, it's impossible to tell without creating a mathematical model of the resulting system with the exact orbits what exactly the influence will be. [Answer] Unfortunately, if you want the Moon to be the same as it is in the real world, this will be a problem. The problem is the distribution of the elements & their ratios is the same as it is for Earth. Which means the Moon shared elements with the Earth at some point in history. Massive flow or major impact. We've got some theories on how we got our moon, but none of them answers all the questions given our current state of knowledge. ]
[Question] [ In the magic system I've been workshopping, magic is powered by the caster's emotions and memories. Specifically, mages can shape spells by creating associations to their own memories, and strengthen those spells with the emotions those memories conjure. A happy memory of sitting around a campfire with good friends or family, for example, could be used to cast powerful fire spells. The main character, however, is special (as main characters tend to be). Instead of being limited to this emotion-memory system, they have a large reservoir of magical energy to fuel their spells with instead. This doesn't mean that their emotions or their memories are necessarily stronger than those of others: their "innate magical power" is a separate thing. The way I see it, I have a perfectly good process for casting spells (the emotion-memory system), but I want to staple a completely unrelated process onto it. How do I make these two systems play nice together, or at least be internally consistent with each other? How do I explain "high innate magical power" in a system driven by emotion and memory? [Answer] ### The Feeling of Magic One way to reconcile it is that the MC has either stumbled upon or been taught how to harness magic without actually casting a spell. Or perhaps it is a magic gathering spell that the MC has in their arsenal. That feeling of sensing the magic in the air, the rush of sensation when you reach for that magic and draw that power within yourself before casting your spell. The sensation of that magical energy infusing your body and comforting you like a warm hug. The raw emotion when your master praised your for the first steps in sensing and pulling on the magic to make a simple puff of air. It's not a boundless well of power -- those lead to negative feelings and thus the power leaving the MC -- but it is magical power that is at the ready. ### The Consequences Normally when a person is taught a spell, they learn to associate the spell with a memory, a feeling, an experience. But that spell also has to draw in the power from around them before it can take shape. This is, in part, why the strength of the emotion and/or memory are important. A weak emotion and/or memory lacks the impact to be able to force itself on the world very much. Meanwhile, a powerful personal memory does have the force because the stronger resonance allows a more powerful effect in reality. In part because that is how people are taught, that is how it works. But for the MC that has a well of innate power? They have both the feelings needed for the spell's effects and the feelings of that power within them. This allows them to tap into their innate power without having to draw upon the outer world until they have to. To use a fire spell as the example: There's the feeling of the campfire the MC's mentor would train by, the light and warmth dancing across their face. But there is also the well of power, the feeling of magic moving to their whim. Of the magic well releasing some of the power and taking the form of the fire in the MC's thoughts and feelings. It is both the memory of the fire and the memory of the magic working to make fire that allows the MC to tap into their well of power instead of their surroundings. ### Possibilities Something that could be possible is that there are others that have figured this out partially. There could be other casters that can do this, but with one or two of their spells -- their favourite ones that they have cast so often that they can actually recall the feeling of the magic flowing to make the spell as well as the numerous powerful emotions when casting their signature spell. [Answer] TL;DR Anyone with a photographic memory would be able to pull from more and more memories as they grow older, while other humans realize how forgetful they are in comparison. "I once knew a girl who either wouldn't or couldn't forget anything. She could tell you the color shirt you were wearing on this day 2 years ago and pulling up a photo she'd always be correct. I had never met someone with such a perfect memory, though she would explain the phenomenon as more a curse than a blessing, living constantly in a rigid world of what once was and is now, while everyone else's worlds were fluid, not noticing their constant forgetting of almost every detail they would experience. She had some habits of writing in journals and keeping calendars that may have helped. I tried to train myself to be better at remembering and I've gained a little skill in it, if that's the word. I can take snapshots, a still image and a feeling encompassing it. I can still see her silhouette clearly in front of the full moon as we float along a river... but that was decades ago, and I couldn't tell you what river or even what her name was, but that image, I still have it. A single frame of my life compared to the entirety of hers... it's no wonder she is a master caster these days while I can barely make ends meet. My workings fueled by what bright scraps of my past I can hold onto bolstered by the building loss and frustrations of my daily existence; yet here she is again, her smiling face front page of the daily paper, surely another miracle of her making." ~potential scene As for having a separate system that may interject, consider the following: Powered by memories and emotions, their brain (or what ever magical organ) is processing these signals while evoking the magical work. The brain may be familiarizing itself with the forces at hand by gleaning the properties of these forces through reliving the memory. Someone with more experience with bonfires and more memories of various fire related events to pull from will be better at fire magics than someone who's held a candle once. Perhaps a new age of magic is on the horizon, a new branch "Arcane" magic. Where the emotional based magic is a natural, sensory dependent way to feel and harness magic, there are underlying forces at play that can be more directly distilled. Rather than focusing on a memory of fire to instinctively learn how to control it during evocation, a mage can study the properties of a magic in more of a lab setting. Rather than feeling your way around fire, you can know it more directly. Rather than encouraging flame to behave as you wish it, will the flame to be as you demand it. There's a lot of unused information contained within these memories pulled when evoking, find out which parts of memories actually contribute to the casting, and extrapolate the common factors. Once found, you only need to remember your understanding on the now and always (physics, if it hasn't been named) rather than pulling memories from the past. The older "emotional" casters will call it cold and souless, but really "apathetic efficiency" is what it is. Perhaps memories are relied on so much because the world may be lacking in a more free "imagination" that we humans in our world take for granted. I have plenty of memories of what it feels like to be standing out in the snow, enough memories that I can conjure new, original memories (imaginations) that allow me to enhance the effects of existing memories by mis-remembering a particularly cold day to be almost lethally biting, the feeling of loss for dropping my coffee escalated to utter devastation. Through hearing stories told by other casters of their magical workings, an imaginative caster can quickly learn new abilities and somewhat copy the powers of their peers by imagining themselves being a part of or even taking the central role within the newly heard memory. [Answer] Your character has a disturbed personality where they get sort of obsessed by details which for others are trivial/easily forgotten. For example if they have seen someone strike a match against a surface, they will be repeating that image in their mind until something else take over, resulting in your magic system being triggered: overthinking of fire ==> amplified fire magic. [Answer] I can think of a couple of options # Isekai Your character was transported from a different universe with a different magic system. # Divine Interference Your magic system works because God (or gods) make it so. For some reason, they have deigned to give your MC a different form of magic. Perhaps they are just experimenting, or perhaps your MC has some role to play in their plans # Your MC found a loophole Somehow, your MC found a way to bypass the need for memories and just cast directly. To figure out exactly what that loophole is though, you'll need to deepen your magic system. # Your MC is a psychopath Perhaps mages need memories and emotions to access magic fields that surround the planet. As a psychopath, your MC bypasses the need for emotions and can access the field directly. This is likely the worst option, as it has major implications for actually writing your character [Answer] ## Symmetry breaking and yoga magic You say that people perform magic by drawing on emotional memories, except for the hero, who does it some other way. One solution would be, as you say, to bolt two different systems together. You can do that, but if that is what happens then your question should be closed because you'd be asking us to invent the entire second system for you, with the only acceptance criteria being that it not be driven by emotional memories; that would be far too open-ended for this site. The only acceptable alternative I can see would be to grow a larger super-system around your memory system, and then explain how the additional parts grant the hero magic. (This is, in a weird way, an analog of the anthropic principle.) That is what I propose to do. I take as my (loose) model [the electroweak force](https://en.wikipedia.org/wiki/Electroweak_interaction#Before_electroweak_symmetry_breaking) and symmetry breaking: > > In particle physics, the... electroweak force is the unified description of two of the four known fundamental interactions of nature: electromagnetism (electromagnetic interaction) and the weak interaction. Although these two forces appear very different at everyday low energies, the theory models them as two different aspects of the same force. Above the unification energy, on the order of 246 GeV they would merge into a single force. > > > Along those lines, we should consider the following questions: 1. What is the larger mechanism, of which emotional magic is just one aspect? 2. How and why did the larger mechanism give rise to two distinct aspects? 3. What is the other aspect that grants access to magic? 4. Why does the hero have access to the other type of magic, when it seems like nobody else does? Emotions and memory are both completely private mental things. The obvious opposites would be public, physiological things. A "whole person" is a combination of their private mental states and their public physiological state. If people can do magic by using one half of their whole self, it stands to reason that the ability has its origin in that unified self. And we're going to stipulate that the other half also provides access to magic, somehow. We might ask: is there a time in a person's life when those two halves are not separated? I propose the answer is childhood, before the person becomes self-conscious enough to make a habit of distinguishing between their mental states and their physical states, a simple time when they just exist and the everyday experience of life washes over them as an undifferentiated stream of stimuli. The picture now becomes clearer: something unusual happened in your hero's youth that led them to have more affinity for their public physiological state than for their mental and emotional state, and this affinity became entrenched when their human development reached the stage where they started to resolve that undifferentiated stream into its parts. The way this person experiences life, the seat of their identity is not the mind inside their skull, but rather their visceral and tactile body. So, how does the public, physiological identity grant access to magic? It's a very common trope for spellcasting to require a physical dimension, usually hand or body movements, and that's how it is for your hero. The best fuel for their magic is not vivid and emotional memories, but exaggerated or even strenuous physical motion. Imagine something like an [aircraft marshaller](https://en.wikipedia.org/wiki/Aircraft_marshalling): [![helicopter marshaller signalling "turn left"](https://i.stack.imgur.com/dZT2s.png)](https://i.stack.imgur.com/dZT2s.png) Presumably, the reason your hero has a lot of this kind of magic is that they are very fit and in touch with their body. Perhaps they are a yoga instructor, or a serious gymnast, etc. [Answer] We all recall memories a bit differently. Main characters way to recall memories is somehow just right, somehow meshes extremely well with the fabric of the world. Perhaps his (quirky) way of remembering tells us something deep about how the world fits together? I have met some wonderful\* people in this, that just seem to bend the world around them. When they laugh, the people around them feel better. They dont have to be beautiful by my standards, they bend reality to have standards that fit them. Kind of a high charisma, but not entirely, it seems like their emotions carry weight, in a strange and powerful way. I expect they would be very good mages in your world. You could do a full reversal, and make it a plot point. Your main does not have any long term memory, and lives by his book of notes and short term memory. His head just can't carry the weight of his incarnated vault of everything. What if he never feels anything, and has made a mask of false emotion, in all of his life? He is so adept at faking it, and has such an empty slate to work with, that he can fake any emotion needed for any spell. Your main char cannot live in the present, he is all nostalgic emotion over the past. If he has to go somewhere new, he needs to read up on it first, to get a memory of it. His sole devotion to backwards-looking emotions cripple his life, but gives him massive magical prowess. So much psychologically interesting points to explore. \*Both in the regular sense, and the "Elves are wonderful, they beget wonder" sense. ]
[Question] [ People who "... do not have more than 65% of their brain function provided by natural human neural tissue" according to a new, pernicious and poorly thought-out law "shall cease to be legal persons and become property of the nearest family member or holder of greatest corporate interest." Brain implants have been a wonderful new medical technology. They make Alzheimer's less aggressive and destructive, they calm seizures, they even have made addiction possible to conquer for millions of people. Some 40% of the population have some form of artificial addition or replacement in their brains. But, there have always been objectors and conspiracy theories. The lack of transparency of some companies due to IP concerns isn't helping. Fear rises of "mind controlled" people taking over the government or changing society forever. The first law passed makes it illegal for children to receive brain implants the next targets those who hold public office, this makes the political leaders much more likely to be skeptics or worse people who believe the most outlandish conspiracies. The momentum for the "65" law gains steam and now that it is passed it must be enforced. * How will it be enforced? * How can people try to get around the law and keep their life saving implants? (To make things more complex there are ways that those with larger proportions of machine intelligence can seem very different from the 'pure unmodified': Their uncanny memories, their ability to 'talk' to each other effectively through telepathy-- and there are some who think we should do more than just cure disease-- we should actively seek to improve the human mind-- among them is 98, so named because 98% of his brain has been replaced over about a decade. He's a lightning rod figure in the political debate, and some people who simply have one or two small implants think his rhetoric just causes trouble) [Answer] # Power requirements / limits Poorly thought out laws demand poorly thought out limits. So some "brilliant" law maker was once told that "CPU cycles demand power". One cycle equals so and so many millijoules / one in a thousand-twentyfourth calories. And one CPU cycle equals so and so much computing power. The idea that eventually coagulated was that all implants draw power from electrical batteries, so if we set a limit to the amount of energy they may use per day, this puts a limit on the amount of usefulness you can get out of them, and provides an "interface" by which the government may poke their noses in it. And not only did this "brilliant" congressman manage to make it a law, they made it a constitutional amendment (assuming your setting is mostly US-focused). So, now that power requirement is frozen for a very long time. Of course, this was obsolete even before the ink dried on the paper. * Power management, the "power cycle" was made much too long — a day or more — which allows people to use it cleverly, in boosts when they really need the implants. * The amendment was — true to style — written wrong; it specifies how much energy may be drawn from the battery pack per power cycle, but not where you put it, so that Alice can draw energy from Bob's power pack, and get a double allotment. * Newer designs use less power. The more expensive, the less power they draw while still providing the same functionality. Exotic elements — that make implants stupidly expensive — lower the power requirements drastically, giving you a class perspective: the filthy rich can augment themselves silly, the middle and lower classes plod along with older, conventional designs. * The law did not specify actual energy or wattage, it specified that common unit by which battery capacity are normally measured: milliAmpereHours. As anyone that knows their basic electrics is aware, if you then up the voltage, you get more energy for the same amount of mAh. Hence, high-voltage power packs provide yet another loop-hole. Downside is that these are pretty dangerous! Having a 400V or more socket in or on your body is associated with risk. * People go to shady clinics that promise to be able to sneak them extra power connections that bypass the government power meter. Sometimes it even works. * From Somewhere-In-The-World there is a bio-compatible fuel cell implant available that draw fuel and oxygen from the blood, though you have to inject this fuel into the blood, or eat some kind of supplement. Naturally these are completely banned in the US. * There is rumours about bio-energy machines, that draw power from the [ATP cycle](https://www.studyandscore.com/studymaterial-detail/atp-cycle-structure-and-role-of-atp-in-biological-reactions). Vastly advanced stuff, and most people claim it is nothing but a conspiracy theory. --- So, how this enforced? * By a law / constitutional amendment that limits the amount of energy implants may use per day / two days / week / time limit of your choosing How do people bypass this? * By messing with how much energy the implants use; when they are actually using them; power trading; barely or non-legal body modifications that provide extra power; non-electric power sources. [Answer] Existing legal infrastructure is sufficient for this. Where there is a dispute on who owns the cyborg (or if the cyborg is cyborgish enough to be owned), the civil courts will take over. When owned cyborgs try not to be owned, the police will step in (and if it's a big enough problem, they'll set up a special police force for that). The only weirdness implied by any of this is in international law and foreign policy. Will Netherlands try to become a safe haven for fugitive cyborgs? Dunno. How will the United States respond, if they do? Dunno. [Answer] # Miniaturisation If we look at how technology advances, one important advancement is miniaturisation. Take computers. Where we used to have a room with a wall to wall machine for some 'simple' calculations, now we have phones in our pockets who are billions of times stronger and can last a day on a battery. If you knew the old gameboy with it's simple screen you'll appreciate it kore, because it didn't last long on a battery. Making the implants smaller can reduce the percentage of brain that is a computer. You can cram more of it into a brain before it becomes a problem! # Switching How about just having your normal brain with 98% implants, but still being legal. What constitutes as 'part of the brain"? When it has a connection of course! So what we do is give the implant a bunch of information and close the connection. The implant is no longer seen as part of the brain, while still doing the calculations you want. It resumes the connection when it is done, giving the information back to the brain in a split second. Then closing the connection again until the implant is required again.if it is managed right, you can have the whole brain and implants operating at the same time, while still not crossing that 65% line. Even more interesting is that you can have the implants talk to each other directly, bypassing the brain for most if the time. That way you can be 98% implant man, but being classified as human. You're not in connection with most at any given time, so you're perfectly legal. [Answer] ## How is it enforced? How is any government restriction on goods or services enforced? *Paperwork.* You want an implant. The hospital files paperwork with the state health department documenting the proposed implant and how much of its brain activity it's supposed to replace (something the manufacturer ought to be able to tell them, if this has received anything like regulatory approval). You receive permission and they pop in the chip. Now there's followup paperwork confirming that you actually got the implant, and test results backing up the estimated brain activity level. Now you want another one. But the department looks at your proposal and notes that, with your previous implants, this would put you over the limit. If you go ahead with the procedure, they'll set in motion legal proceedings to strip your personhood. Or, you can decline and try it again some other time. Maybe you get a chip taken out (with accompanying paperwork!) or you find another manufacturer that will quote you a lower value (accepting the risk that they might be underestimating...) or the hospital can produce test results that your natural brain activity is higher than projected. How is this backed up? Audits, audits, audits. Hospitals have to keep records of every chip they received, who it was intended for, their correspondence with the health department, whether the plan was accepted or rejected, whether the patient went ahead with it, and what happened to the chip itself afterward. If they say it's still in stock, it better darn well be in the stockroom. If they say it was returned to the manufacturer or destroyed, they'd better have paperwork to back that up. If your hospital records can't be verified, then the department might decide that they have good enough evidence to presume you had implants put in illegally and start proceedings, forcing you to put up a brain scan proving you're 65% you or lose personhood. ## How is it broken? Better paperwork. Paperwork that says what you want it to say rather than the truth. Manufacturer's "estimates" that are ludicrously optimistic (manufacturers do enough of this as it is!), or that describe a chip that's slightly different from the one you put in - less invasive, or less powerful. Maybe the bureaucrats won't notice the difference. Brain scans from the wrong date and time. Trying to pass off your pre-op scans as post-op, or someone else's scans as your own. Scans with some or all of the data outright faked. Falsified paperwork that shows that you rejected chips when you didn't, or had them removed when you didn't. Falsified paperwork that shows chips being destroyed or resold by the hospital, when they were implanted in you. Fake letters from the health department authorizing surgery. Or, no paperwork at all. Maybe you know a fence who'll sell you chips that fell off the back of a truck. Or a crooked doctor who'll implant anything you show up with, no questions asked, no paperwork needed. Of course, they'll be in prison for a long time if they're caught, and they're expensive, and you don't know if you can trust them - and they don't know if they can trust you. But that's the life of a cyborg criminal. ]
[Question] [ Background: seeking modern technologies, resources, etc that could potentially be discovered and applied in a fantasy setting where manufacturing processes, while advanced, are more akin to the late 1700's. Society has access to "knowledge-base" of advanced species, but A) have currently only been able to interpret/apply portions of it and, B) lacks modern manufacturing technology. My dilemma is composite materials, specifically alternatives to liquid-crystal polymers to be utilized in the production of advanced bowstrings and other materials. I know liquid-crystals are naturally occurring but am unclear if there is any means by which the polymer can be manufactured without leveraging advanced manufacturing processes or needing a natural source (cellulose, spider silk, etc). Examples: dacron fiber, carbon fiber bows, advanced rubbers/resins, etc. * Open to imaginary materials, so long as we don't veer into the "unobtainium" spectrum * Assume hydraulics/pneumatics exist To clarify: how/would a near-industrial civilization be capable of manufacturing materials comparative to dacron, kevlar, etc? [Answer] ## Why you can't make Kevlar without modern equipment. The manufacture of Kevlar has a few roadblocks. Kevlar is made from p-Phenylenediamine and Terephthaloyl Chloride. The p-Phenylenediamine part would be hard but doable. You need Aluminum Chloride as part of the production chain. The production of Aluminum Chloride typically requires electrolysis to isolate the aluminum using the most cost efficient method... that said, there are expensive, not electrolysis methods that you could use to get around this. All the other materials and processes used to make p-Phenylenediamine were available by the late 1700s. The Terephthaloyl Chloride is the much harder part because you need to run naphtha through the catalytic reforming process to get to p-Xylene. This step requires complex and expensive refining equipment, and there is no simple substitute for this step that I can find. p-Xylene is needed at multiple steps in the production of Terephthaloyl Chloride. This said, Kevlar might make good body armor, against bullets, but it does not have the best puncture resistance (which is what you actually need on a pre-modern battlefield). While it might outperform a linen based gambison, it will not protect you better that steel mail or plate armor would against most threats you will face. It is also not a good materials to use in bow construction because it is too stretchy and does not have a lot of snap back like certain other materials. The modern synthetic materials you really want to replace are resin-fiberglass composites and nylon. ## Natural Resin-fiberglass composites The main reason modern bows shoot faster is because they are reinforced with fiberglass. Fiberglass springs back from deformation much faster than and wood or metal allowing a fiberglass backed bow arm to shoot nearly twice as fast as traditional bow of similar design. This said, man-made resins and fiber glasses have naturally occurring counterparts. Asbestos is a naturally occurring fiberglass that people have been using for over 6000 years. In fact, it has a higher tensile strength than most man-made fiber glasses; so, as long as you don't mind occasionally needed to replace some dead bowyers due to its toxicity, it is a great material to use for this. As for resins, there are many naturally occurring options made from various tree saps to pick from. Though you will specifically want to be looking at one of many possible "copal resin" trees. These trees have saps that when boiled, produce a hard amber like plastic very similar to the resins used in fiberglass composites today. While copal resins will not harden as quickly as modern epoxy resins, they can be very tough once set, and have also been in use for thousands of years. That said, resin-fiberglass composites are good for more than just bows. Resin-fiberglass can also be used to improve the construction of ships, wagons, body armor, and tool handles just to name a few. ## Natural Composite to Substitute for Nylon As for the bowstring itself, the most important quality of a good bow string is that it does not stretch under tension. Modern bow strings are typically made from Nylon (Not Kevlar) specifically because Nylon can take significant load without stretching compared to other synthetic fibers. Nylon is much easier to make than Kevlar too, and there are so many different variants of it, that there are a few that can be made without any complex equipment. That said, the ancient world already had a super material that may have been at least as good. Like Nylon, cords made from horse or human hair are highly resistant to streching under load. Some of history's best bow cording material was invented by the Romans using a combination of animal sinew and human or horse hair reverse twisted together and reinforced with hide glue. Not only was this composite cording very comparable to the nylon bow strings we use today, but it does not require any complex chemistry to make. [Answer] If I remember correctly, the Greeks had developed something akin to composites with linothorax: they would wrap linen bandages in a special way and it would become a lightweight and well performing armor. Similarly the Japanese had an armor made of folded paper, which was pretty effective against swords and arrows. It's not unconceivable that something similar can be done by you people. [Answer] Bugtech Silk is the best known of these. Another sweet insect derived biopolymer is shellac. <https://en.wikipedia.org/wiki/Shellac> > > Shellac is scraped from the bark of the trees where the female lac > bug, Kerria lacca (order Hemiptera, family Kerriidae, also known as > Laccifer lacca), secretes it to form a tunnel-like tube as it > traverses the branches of the tree. Though these tunnels are sometimes > referred to as "cocoons", they are not cocoons in the entomological > sense. This insect is in the same superfamily as the insect from which > cochineal is obtained. > > > The raw shellac, which contains bark shavings and lac bugs removed > during scraping, is placed in canvas tubes (much like long socks) and > heated over a fire. This causes the shellac to liquefy, and it seeps > out of the canvas, leaving the bark and bugs behind. The thick, sticky > shellac is then dried into a flat sheet and broken into flakes, or > dried into "buttons" (pucks/cakes), then bagged and sold. The end-user > then crushes it into a fine powder and mixes it with ethyl alcohol > before use, to dissolve the flakes and make liquid shellac.[10] > > > Shellac naturally dries to a high-gloss sheen. > > > Properties > > > ...Shellac is a natural bioadhesive polymer and is chemically similar > to synthetic polymers.[14] It can thus can be considered a natural > form of plastic. > > > ...History The earliest written evidence of shellac goes back 3,000 > years, but shellac is known to have been used earlier.[6] According to > the ancient Indian epic poem, the Mahabharata, an entire palace was > built out of dried shellac.[6] > > > I am not sure about strings and filaments but there was definitely shellacked armor. Silk bowstring is not too wild. Or you could invent polymers extracted and spun from a bug or bug casing like the lac bug, or some different organism along the lines of [Tyrian purple](https://en.wikipedia.org/wiki/Tyrian_purple) extracted from snails. [Answer] As far as I'm aware most of the 1700 was first subtracting stuff and then combining stuff to get what you want. Rather than have people create the base components I would let nature create it for you. In many ways some spider silks can surpass Kevlar for example. The problem is that spiders are mostly solitary hunters that are hard to farm. But there are other bugs that produce silks, and in a fantasy setting you can justify natural pressures to come up with similar spidersilk properties. * a spidersilk worm. Just like the silkworm but adapted to a harsher environment where just that much more protection is needed, either to anchor the cocoon down or to protect against (bug) predators. * spidersilk ants. The weaver ant uses the larvae's ability to create cocoon silks to construct ant hives from leaves in the trees. An adaptation could see stronger silks created and subsequently farmed from them. Graphene and especially Carbon Nanotubes are a tough but flexible material that have good properties in materials they are captured in. Damascus steel for example has it. I had a discussion with someone and we found a variety of different articles which indicated that almost every part of the process to create Graphene can be done by a biological being (bacteria mostly). If a creature used this in things like a shell, bone or tendons to strengthen themselves and these people farm these creatures in order to extract the CNT's and use it in something else, they could create strong composite materials without even knowing what a composite material is. You can also have a type of sapling create CNT's and be an excellent (if tough to cut down) material for bows. ]
[Question] [ A few decades ago the Third World War destroyed Earth. Space infrastructure was considered a priority target by both sides. Orbital space was in the years before the war was filled with skyhooks, power satellites, zero-gee factories, several habitats, shipyards, and so on. The mass of the entire infrastructure within 1000 km above the surface was about 10^10 kg. The timeframe I'm interested in is the first few decades after things went down. I guess the whole thing would get worse over time as more collisions happen. Since both sides feared that a single surviving enemy space station might be able to purge the remnants of their respective faction using its launch assist system (laser arrays, tethers, electromagnetic launchers), they pursued a policy of ensuring absolute overkill against any space structure. As further-out debris won't be visible from Earth, they are irrelevant for the purpose of this question. Concerning debris sizes, the largest ones will be a few dozen meters long. I suspect that a graph depicting the relationship between the number and size of debris will show a long tail distribution. So what effects will this have, especially visual ones? (Spacetravel is kinda low on everyone's priority list.) I imagine that shooting stars would be the new normal and that especially the night sky would be filled with bright and fast-moving debris. Would the night sky become milky due to the high number of small particles? Additionally, the infrastructure would mostly have existed around the equatorial plane, so how would an observer's position on the planet change what they see? [Answer] Permanent skyglow If Kessler syndrome does occur, most satellites in orbit would be properly shattered, which means that few, if any, would be seen with naked eye. Significant proportion of the mass would depart low Earth orbit and fall to Earth over few decades, however, there still be more than enough in orbit to cause visible effects. Total mass of 10^10 kg is almost 3 orders of magnitude higher than the total estimated mass of satellites today ([What is the total mass sent into orbit over all history?](https://space.stackexchange.com/a/5779/22029)) According to [this source](https://academic.oup.com/mnrasl/article/504/1/L40/6188393), today's satellites contribute at least 1.6 E-5 cd/m2 of luminance to the dark sky. Assuming that satellites are fractured to an average 1/100 of their size, their total luminance should increase by the factor of 100, which, for today's satellites would give us 1.6 E-3 cd/m2. Further assuming that future's satellites would be pulverized to the same sized debris, we arrive at about 1 cd/m2 skyglow - which would be at the peak of Kessler syndrome. Next assume that 50% of debris would deorbit in the next several years, and we arrive at 0.5 cd/m2 total average skyglow. For a night sky, 0.5 cd/m2 is a lot. This is the luminosity at civil twilight, when sun is just set (or about to rise), when sky outshines full moon by far and people can do reading and writing almost comfortably. Observations of celestial objects at this stage is almost impossible - only brightest stars, planets and the Moon are visible in twilight. This skyglow would not be uniform - it will be brightest towards the direction of the Sun and faintest in the direction opposite to it, in Earth's full shadow, or umbra. [Answer] (frame challenge) Q: "A few decades ago the Third World War destroyed Earth" ## You won't see it coming in, through the dust of nuclear winter First, I wonder if your "debris storm" would last for decades. When debris reaches the upper atmosphere, it could take only a few weeks or months, to be decelerated and fall. Not years. Second, we're talking about 10 million tons of space debris. Half of that would not reach the atmosphere (go into higher orbit) and only a small part would consist of material that can reach earth. When "the earth is destroyed" as you state, that destruction cannot be a result of 4-5 million tons of space debris penetrating Earth's atmosphere, let alone the small fraction of that debris large enough to cause damage on impact. So I have to assume, because you say "the earth is destroyed" there would have been a nuclear war on the planet surface as well, resulting from nuclear attacks on cities. Such a war would cause a nuclear winter, with lots of dust blocking sunlight for years. The sky would look grey. The falling debris from space would not be visible at all.. and surprise the survivors with sudden havoc. ]
[Question] [ My fantasy world Treyidal is a planet inhabited by two races, humans and merfolk. They live on a very seismically active world, with such things as micro-magic based earth quakes. For the moment we'll put all that aside, and just look at one aspect of the world. If viewed from space, Treyidal has the peculiar feature of looking like tidal pools almost, being composed more of inland seas than large oceans. A number of these seas need to be more shallow than oceans on Earth, to facilitate a comfortable habitat for the merfolk. So what negative effects would result from these shallower smaller seas? Possible ways to circumvent problems I see: * Have more groundwater * Don't have true oceans still, but divide the bodies of water more with small segments of land * and the regrettable option, handwave it away with some magic, though hopefully in a good, logical fashion I think that lack of broader ocean currents would be very tough on all of this world, lacking the ability to spread things like warmer water to farther north climates. Also, erosion would've probably made the oceans larger over time anyway, wouldn't it have? All this aside, here is a very, very rough map of what I've thought about so far with my world. You can see that the prominent body of water in the center, the Aliya sea, is not necessarily required to be a true inland sea, though I do want a good amount of these. Basically, I don't want a world where continents appear to float on the ocean, but more like the water is penned in by the continents. [![Rough map of the Aliya Sea, with the human nation of Havla on the north coast.](https://i.stack.imgur.com/fCoWE.png)](https://i.stack.imgur.com/fCoWE.png) [Answer] Well, a few things to consider that may or may not be inconsequential, or may even be nice extra flavor for your world! Please keep in mind that I'm simplifying matters greatly so this answer isn't pages long. ## Oceans as a Buffer One of the most overlooked effects of massive and deep bodies of liquid is the equally massive and deep volume of dissolved gasses and stored heat. Near the coast, air temperatures are generally far more stable due to the huge heat capacity of water. Even well into the next season, the oceans usually lag behind in temperature keeping air temps more stable not only over the course of seasons, but days as well. Take deserts for example, which due to the lack of airborne water can vary from freezing to dangerously hot over the course of a single day. Temperature isn't the only thing regulated by the oceans, gasses are also kept in check. On our planet, [2.4 gigatons of carbon dioxide](https://earthobservatory.nasa.gov/features/OceanCarbon) are absorbed by the oceans each year, putting a noticeable damper on rapid changes in the makeup of the atmosphere for any gas that's dissolvable in water. This can have more profound effects during extinction level events, although I'm not sure that that will be relevant in your story... ## Albedo With less surface water, your planet is actually less likely to experience ice ages due to the water-ice-albedo feedback loop being much harder to perpetuate. This could play an important role in some evolutionary paths. ## Desertification Unfortunately, you planet would realistically be covered by vast swaths of desert. Desert formation has very little to do with temperature, and everything to do with weather patterns. If there are no wind patterns that will carry warm, wet air from an ocean all the way to the center of your continent, you're going to have barren areas at best, and massive deserts at worst. This is hard to circumnavigate, as precipitation generally comes from the evaporation off of large bodies of water, and fewer, shallower oceans means less evaporated water, smaller rain clouds that won't make it as far inland, and consequently more barren landscape. [Answer] A lack of large fish. This may be good or bad; you are unlikely to evolve whales or sharks in a lake; the food supply would not support it. I don't know if your merfolk depend on large game. Variability in water level might be an issue; we have had pretty large inland lakes drop 20 feet in a drought, or nearly disappear altogether. For freshwater lakes, freezing over might be an issue. Tides may be extremely muted; some marine species rely heavily upon tides, they agitate the water and stir up nutrients, or bring new nutrients to the beaches. A lack of tides may mean a lack of beaches as an environment for some marine animals. [Answer] * Less Rain: Small water bodies will produce less water vapors, leading to lesser rains which will affect vegetation and cultivation. * Dry up: Smaller land locked water bodies could dry up for certain reasons. Examples are reduction of Aral Sea (26000 sq mi in 1960 to 5510 sq mi in 2010), Lake Chad (8500 sq mi in 1966 to 120 sq mi in 2006). Some water bodies could vanish at all e.g. Lake Poopó, Hamun Lake etc. * Transportation: Water ways are cheapest mode of transporting goods for long distances. In your world, water ways are for small distances only. [Answer] No mountains. On Earth, the ocean floors are important parts of the moving of continents. All the subduction zones are where the deep ocean floors are going under the continents both moving continents and creating mountain chains. Without the Andes mountains, South America will have very different climate. If the land masses don't move around, then you will see very strong differences in animals based on latitude. [Answer] Where the world active enough that the location/composition of those seas change "geologically" often, It seems to me that the human folk may have histories of, or still be nomadic or partially nomadic, depending again of how fast it changes, can you build a structure that will last more the a decade? a century? a millennium?... what affect does that have on history... Maybe there are a few or one relatively stable enough area that a city could be build. this could be a considerable power imbalance to the ones that cannot build lasting settlements. Similar for the Merfolk. How "corrosive" are the seas? could a stable settlement be built on the seaflor or suspended in the water? if the topography changes often enough, perhaps because of the isolation of the seas there is more diversity of language & culture... maybe even divergent or specialized physiological adaptations. The world it self wold be more dry, warmer, similar likely to the Iberian region of Europe or the Anatolia region of Asia ]
[Question] [ I'm trying to construct this organism in my world, that is completely biological, but is almost like a large human-esque brain organ with slug-like apparatus extending from it. Like multiple tentacles and minor organs for sight and sound, and overtime these "tentacles" form the basis for piezoelectric muscles for movement and "growing" over something, which is where I lead to: The idea is human and fellow cyborg crews grow these brains from infancy till they're large enough to have metallic plates, hydraulics, rotary things that these tentacle-muscles can grow upon and their "body" to essentially become humanoid in shape and action. Its brain organ is slightly smaller than ours, but its neuron compression and incredible muscles allow it more processing power and strength than us, they just require facilitation into the world. The origin story is they're sentient organs made to be implanted into spaceship components and cyborg bodies as long-living servants. They were grown upon the surfaces of planets and inside large biolabs so they're completely natural, but in their super-tech days these brains would barely need its tentacle-muscles for anything, thus its smaller size compression allowed greater productivity. Basically my question is surmised, how feasible would these creatures be overall with a mechanical chassis essentially built around their bodies? [Answer] > > Hard to ask my question, but where should I begin and stop in regards to how much this organism should be cybernetic? > > > A problem you will need to solve - "use it or lose it" 1. if the brain doesn't exercise a function immediately after it was born, the volume of neurons dedicated for the function will be taken out by other functions ([brain plasticity](https://en.wikipedia.org/wiki/Neuroplasticity) and all that). 2. the brain must actively function to "cast itself and maintain itself into a shape". It does need to receive inputs from the environment - search "sensory deprivation experiments to get some of the side effects - e.g. [despair, disorientation, hallucinations](https://www.motherjones.com/politics/2012/10/donald-o-hebb-effects-extreme-isolation/). And, to a slightly lower extent, needs to exercise some control over the environment (e.g. search for "psychological impact of paralysis"). See also ["I have no mouth and I must scream"](https://en.wikipedia.org/wiki/I_Have_No_Mouth,_and_I_Must_Scream). 3. a sentient functional brain will require a "sense" to exist. Not only it will need a definition for "carrot" and "stick" (in an existential way), but it will need to exercise being in states that involves both. Sorta metaphorical speaking here, but somehow that is to say a lifetime of only dopamine is as nonsensical as a lifetime of adrenaline - one needs to feel a "sequence" of both to "feel alive". Bottom line, your "sentient organs made to be implanted into spaceship components and cyborg bodies" will need: * to be given a body as soon as their are "born" (or put in some kind of stasis until they can get a body) * have the "job" defined to them, because the "job" will actually define them * get to reach a definition of "their purpose in life" * it is unlikely that one can switch bodies once "sentient organisms" got their own. Brain plasticity goes only that much - think switching everything above as a "trajectory" through many [zones of proximal development](https://en.wikipedia.org/wiki/Zone_of_proximal_development) between the starting point and the ending point. * be used in situations that do require constant interaction with the environment. Placing a "weapon targeting specialist" inside the "turrets" and expecting it to be functional after some years of doing nothing is not gonna work. [Answer] ## Yes. Whay you've invented here, is called wetware. These hypothetical systems use neural tissues as an organic processor for the machine they reside in. Your idea is actually a bit overengineered since you don't need it to have any sensors or muscles, and everything it needs to function can be provided by the mechanical body it's being implanted in, so it'll be essentially just a braincase large enough to perform the functions expected from it, with a life support system attached. ]
[Question] [ Assume that an external force nudged along the evolution of a mammal and/or insect species towards an appearance mimicking as much of humanity as possible - skin, mouth, language, fingers and thumb, etc - while capable of flight (like a hummingbird? or Tinkerbell). Assume that their minds are built and wired differently to allow higher intelligence, if needed. Would there be a size they could be viable as a species capable of flight (including hovering)? What would be the range of height and weight for such a species? How would their biology differ? Diet? Would they be capable of human-like speech or would their speech be different? [Answer] I'm assuming you mean 'how small' could they be? For the viability of a humanoid body plan we can look to the [pigmy marmoset](https://en.wikipedia.org/wiki/Pygmy_marmoset). Smaller than that may be possible but clearly 'as small as' definitely is. [![enter image description here](https://i.stack.imgur.com/t3THC.png)](https://i.stack.imgur.com/t3THC.png) Could something that small speak? yes, ask any budgerigar. Can they fly at that size? lots of things that size fly. It's just a matter of giving them adequate wings & appropriate musculature to drive them. The smallest mammal by weight (I assume you want them to be mammals?) is the [Etruscan shrew](https://en.wikipedia.org/wiki/Etruscan_shrew) weighing about 1.8 g (0.063 oz) on average with a body length of about 4 cm (1.6 in). [![enter image description here](https://i.stack.imgur.com/BBU0a.png)](https://i.stack.imgur.com/BBU0a.png) The [bumble bee bat](https://en.wikipedia.org/wiki/Kitti%27s_hog-nosed_bat) (a flying one for you) is about 29 to 33 mm (1.1 to 1.3 in) long & 2 g (0.071 oz). [![enter image description here](https://i.stack.imgur.com/p4mcM.png)](https://i.stack.imgur.com/p4mcM.png) So I see no reason you couldn't go down to their size (though as there's nothing smaller than the Etruscan shrew that's likely your smallest reasonable limit for a mammal). Their voices may be a bit distorted & high pitched that small but I see no reason they couldn't still talk. How would their biology & diet differ? shorter lifespans, higher metabolism, faster heartrate & having to feed far more frequently are strongly indicated by our knowledge of small mammals. Intelligence is a whole other ball game, human intelligence in a hard science context for something this small is not really possible, with a bit of handwaving you might get away with equivalence to [a Three year old toddler](https://raisingchildren.net.au/toddlers/development/development-tracker-1-3-years/2-3-years) for a larger (than a smallest possible) model without too much grumbling from the pedants, but the smaller you go the softer the science & ever more handwaving needed I fear. --- Have a look at [this answer](https://worldbuilding.stackexchange.com/a/158515/49261) (you've reminded me I haven't finished tidying it up, thanks, I'll have to get onto that) to a related question & other answers to it, you may find they give you some ideas. --- Later edit: I'm 100% satisfied with my conclusions on size but not entirely with those on intelligence. In tests a Raven does roughly as well as a Chimp & both are considered roughly equal to a two year old, they do better in some areas but broadly speaking across all tests that seems to be the consensus on where they average out. But the Raven does it with more or less 4% of a Chimps brain mass (about 15g), we think they achieve this with [a greater neuron density than in mammals](https://www.pnas.org/content/113/26/7255). Extrapolation from that suggests a 54g brain (assuming the human average of 2% of body mass that's somewhere between a one foot six inch & two foot tall person I think? meh! someone else will have to do the math on that for you) using the same tricks birds do to cut brain weight (to make flight easier) could plausibly be as bright as an adult human. But I'm far from convinced it can simply be scaled like that to produce human level intelligence & the danger is new work in the field could potentially make any such extrapolation appear silly tomorrow or that there already is work out there that does I've just not come across. You need an expert in the area for that one. --- You'll find [other answers on size & intelligence in this question](https://worldbuilding.stackexchange.com/questions/213848/does-size-limit-intelligence). --- [Answer] A 4.6 g hummingbird has a wingspan of 117.5 (4.6 inches). For an average human female of 159.5 cm (5'2") tall and 53 kg (117 lb) to fly like one, it would need a wingspan of about 12.6 meters (41.4 feet), which is very impractical and wouldn't work. If it was much shorter, say 50 cm (1'7") tall and 1.6 kg (3.6 lb), it would still need a wingspan of 2.19 m (7.2 ft). If it were only 85 grams (3 oz) and 18.7 cm (7.4 in), then it would only need a wingspan of 50.5 cm (20 in). ]
[Question] [ The cold war never ended in 1990-94, and the Warsaw pact still exists, as does the prominence of communism in eastern europe. It’s now 2030, and both sides have colonies on the moon and are establishing colonies on mars. Ignoring the technical the fact that both sides now have prominent forces in space, what would have caused the Warsaw pact not to fall, communism and the cold war to continue and Gorbechev to live through the coup during 1994? [Answer] 1971: the Soviets are invited back to China by Lin Biao. > > Lin Biao officially became China's second-in-charge in April 1969, > following the 1st Plenary Session of the 9th Central Committee of the > Communist Party of China. Lin's position as Mao's "closest > comrade-in-arms and successor" was recognized when the Party > constitution was formally revised to reflect Lin's future > succession.[76] At the 9th Central Committee, Lin's faction was > unquestionably dominant within the Politburo... Because over 45% of > the Central Committee were members of the army, Lin's supporters > dominated the Politburo, and Lin's power was second only to Mao's.[77] > > > During the Second Plenary Session of the 9th Central Committee, held > in Lushan from August–September 1970, Mao became uncomfortable with > Lin's growing power... Because Lin was one of the most influential > figures in promoting Mao's personality cult, he began to be criticized > within the Party for its excesses later in 1970.[18] . > > > A serious rift developed between Mao and Lin. Mao was displeased with > comments that Lin had made about his wife, Jiang Qing, at the Lushan > Conference. Generals loyal to Lin refused to accept Mao's criticism of > them... In July 1971 Mao decided to remove Lin and his supporters. > Zhou again attempted to moderate Mao's resolution to act against Lin, > but failed... Lin died when an aircraft plane carrying him and > several members of his family crashed in Mongolia at 3:00 am[81] on > September 13, 1971, allegedly after attempting to assassinate Mao and > defect to the Soviet Union > > > <https://en.wikipedia.org/wiki/Lin_Biao> In this timeline, Lin is successful in assassinating Mao. In the chaos that followed, Lin needed an edge to take control of the Chinese state. He found it with the Soviets who were reintroduced as the pure keepers of Communism and an antidote to the brutal excesses of the cultural revolution. The USSR and China were good for each other, the USSR providing a stabilizing influence and quicker recovery from the chaos of the 1960s and Chinese economic energy providing an antidote to Soviet economic stagnation which would ultimately lead to the dissolution of the USSR in our timeline. Sino-Soviet cooperation make them an adversary to be reckoned with and the Cold War continues unabated. --- I like this too because the Sino-Soviet cooperative Communist entity would be fun to write, and a change from "Soviets in the Future!" which usually is just the Soviets from the past with ray guns. [Answer] You must repeal the Outer Space Treaty (1967) The [Outer Space Treaty (1967)](https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/introouterspacetreaty.html) expands on a set of more general principles (1962) from the dawn of manned space exploration. It is one of base documents of International Law governing space. It includes the following principles: > > * The exploration and use of outer space shall be carried out for the benefit and in the interests of all countries and shall be the province of all mankind; > * Outer space shall be free for exploration and use by all States; > * Outer space is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means; > * States shall not place nuclear weapons or other weapons of mass destruction in orbit or on celestial bodies or station them in outer space in any other manner; > * The Moon and other celestial bodies shall be used exclusively for peaceful purposes; > * Astronauts shall be regarded as the envoys of mankind; > * States shall be responsible for national space activities whether carried out by governmental or non-governmental entities; > * States shall be liable for damage caused by their space objects; and > * States shall avoid harmful contamination of space and celestial bodies. > > > This treaty quite cleverly makes space not worth fighting for. Territory cannot be claimed by a nation, so there is no territory to defend. War production and military-supporting activities are prohibited, so there are no legitimate military targets worth attacking...so there's also unlikely to be any acceptable reason to station space-based forces and garrisons to protect those non-existent targets. The problem with repealing this treaty is that it permits all kinds of exploitation -- a wide-open frontier ripe for brave and intrepid barons from around the world without moderation. Analogous frontier conflicts of Australia and Argentina and the USA weren't simmering cold wars -- local barons fomented many small-and-nasty hot conflicts over control of resources or plain old politics. And that's exactly the opposite of the powerful centralized control that keeps a cold war cold. [Answer] ### The shooter on the grassy knowl missed Kennedy survived his assassination attempt in Dallas, and continued on for a second term but after the fall out from bay of pigs and being caught with a mistress lost control of both chambers of Congress. Rather than being a martyr for the cause of space exploration, Kennedy led a minority government that accomplished nothing. The outer space treaty was never signed. USSR was first on the moon, and stayed there, they started mining and refining in space and building permanent military bases and colonies. USA dismissed this: "Let them skip around in the dust - the more soviets that leave Earth the better!". It wasn't until Reagan came along with his "evil empire" rhetoric that the USA was motivated to get into space, by which time the moon was firmly Soviet. In the early 90s USA launched a massive fleet to the asteroid belt to mine some of the more promising deposits and build a colony and military base around Ceres, which is rich in water and thus oxygen and fuel. The USA is getting richer and powerful as the asteroid belt has insane deposits, but the moon is in a strategic position to cut the USA off from its colonies. The ussr promises safe passage in return for payment, which the USA begrudgingly pays, for the moment. [Answer] Gorbechev staying in office would help but that only part of problem. While he did have good intentions he inherited a failing system That was already dependent on prisoner slave labor, Serfdom Forced draft And other nastiness. No to make this work You have to go back further and you gonna need a lot of hand waving. 1. Stalin never rises to power. This would not completely fix the USSR But it would have certainly improved it. Lenin didnt want Stalin to succeed him anyways. The cold war would still happen even with out Stalin but the USSR would have fewer problems probably. 2. Somehow the Soviet Union convinces the captured members / Vassal States that they are better in the Soviet Union than out of it. This is something that they never succeeded to do in our time, And require honest you Going to have to be a little hand wavy with this. Either there's less of independence Movement in the members of the Soviet Union or Russia is just better at assimilating Or for some reason there propaganda was more effective in this timeline. Maybe there was Already large Communist movements In these countries before they were taken by the USSR. 3. Communism works somehow. A major factor in the defeat of the USSR in the cold war is that Communism Just couldn't provide the quality of life for your average citizen that capitalism could. That is going to have to change. Perhaps there's another great depression that equals things out a bit. Perhaps a The USSR last long enough That they're able to fix The holes in the communistic system. Maybe they find some resource that they're able to sell to other countries and managed to get rid of the corruption enough that they actually do distribute Their wealth among the workers. You may have to get a bit creative with this one. ]
[Question] [ It is my dream that humanity can one day become a multi species civilization. As someone who feels like a stranger on this planet, it would be nice to have some company in that regard. But aside from the difficulties of making sure all those species are comfortable around humans in our environment, and shutting up those, “Suffer not the Xenos to live” nut jobs, one trial that might face such a civilization is increased stratification based on special traits. Imagine a species from a volcanicly active world with incredible heat resistant skin and lungs used to filtering out all kinds of toxic gases. You now have someone who can walk through a burning building without protective gear and not mind. The perfect fire fighter. Then there is the classical big scaly warriors with bullet proof skin and infra-red vision that would make a perfect frontline soldier. Then there is also the smaller honorable warrior code species with eidetic memories that make the ultimate law enforcers. A more tech savvy species might design our computers. Or the math wiz species that thanks to accurate stock predictions become top of the Forbes 500 List. Or more medically minded species becoming doctors. Or shapeshifters practically running Hollywood. Now I’m not trying scream “the E.T.s are stealing our jobs!” That is not what this is about. I am just wondering if this might lead to the removal of social mobility that makes our society great in the first place. Because if everyone is doing something that gives them joy and makes the galaxy a better place, that’s the whole point, and no one wants it ruined by some jerk saying, “Sorry, but you’re just not the right species for this job.” So my question is: Should we be worried about a caste system based on species traits in a multi-species society? [Answer] No one is forcing women to be nurses. Yet the lionshare of people studying to be a nurse is female. The year I started studying to be a nurse there were more than 300 applicants, 7 of them male. All years saw similar numbers. This was all by choice. Similarly other studies and jobs are predominantly male. Women might complain not enough women are represented in high positions, but less paying positions like construction or ICT are also predominantly male jobs. This is again by choice. Your species arent forced to work in their most advantageous field. They might WANT to, but there is no requirement. And if a fireproof species comes to find a job as a scientist and he scores highly in the fields you want a scientist for, why wouldnt you hire that person? Will there be bias? Yes ofcourse! But if we get that far in the future we have either made a dystopia or have the tools and means to not let bias ruin the decision. You might even see computers being the recruiters instead of people who have to judge someone based on a paper with information and a few meetings. [Answer] > > Should we be worried about a caste system based on species traits in a multi-species society? > > > No. What you've listed are not species traits, they're stereotypes. Human history itself is full of racist and sexist stereotypes, few of which stand up to any kind of closer inspection. I mean, seriously: > > the smaller honorable warrior code species with eidetic memories that make the ultimate law enforcers > > > Warrior code? honourable? For every single member of the species? No dissent? No conflicting backgrounds? It sounds like you're working with a whole galaxy of [Planets of Hats](https://tvtropes.org/pmwiki/pmwiki.php/Main/PlanetOfHats). Either you designed it deliberately from the ground up to make specialist species in order to create this society, or you're just a bit lazy (not that there's anything wrong with that; conserve your creative efforts for whatever you like, but this is where you've ended up). > > I am just wondering if this might lead to the removal of social mobility that makes our society great in the first place > > > The big scaly guys are just the equivalent of big hulking bouncers and bodyguards. They'll have a niche, but technology is a great equaliser and they won't make up even a large proportion of any armed force. In the future, being bulletproof isn't as useful as being vacuum, laser, radiation and nuke-proof and no meatsack is gonna achieve that by themselves. Sure, the techy people make nice gear, but everyone else bootstrapped themselves into the wider galaxy... shiny consumer goods are great, but they aren't the be-all and end-all of engineering, and the fact that haven't turned themselves into postsophont demigods shows they don't have anything we don't. The mathematical wizard stockbrokers just got replaced by AIs, because they think like meat-glaciers compared to computers, regardless of how neat their ideas might once have been. The firefighters got replaced with expendable robots because we care about alien lives, too. Why put living beings at pointless risk? And it turns out the "honourable warrior code" folk had a terrifying monomaniacal drive that's lead them to commit acts of genocide on a scale undreampt of by the worst of humanity, leaving only the core of true believers behind. That's why an entire people all follow the exact same code of honour, because they hunted down burned everyone who didn't. On a related note, we have several thousand vacancies in law enforcement. People with singleminded and inflexible moral codes should not apply. --- Also, nitpicky note... the things you're describing aren't quite castes, due to the lack of stratification. I'm not sure what the correct term is for this kind of genetic equivalent of a guild or union, though. [Answer] Yes very worried indeed. The world used to be a multi-species society. There were multiple species of hominids alive at the same time such as Homo Sapiens and Homo Neanderthalensis (depending on how you wish to define species). It didn’t end well for the Neanderthals. In more recent times major sub groups within exactly the same species (Caucasian and Negro) have been the cause for a caste system - if slavery can be called that. And even in a society with a relatively uniform culture such as parts of the Indian subcontinent a caste system has evolved. So there is little prospect of a multi-species society living in harmony if one of those species is Homo Sapiens. [Answer] Fundamental philosophy. This is an excellent text sample for those studying the society of pre-Contact Earth. Like so much of their culture, it was packed with irony and unresolved conflict, the seeds of elementary-school philosophies that at that time were still undiscovered. Seldom was their science fiction so directly suitable for classroom discussion. We should draw special attention to "capitalism", which is a difficult concept for the student - or even the expert - to comprehend. In the narrow sense it preached the primacy of free markets, while stamping them out at every occasion with remarkable brutality, and of capital, as it organized the destruction of planetary production potential. In a broader sense, it meant the duplication of unnecessary labor in the name of efficiency and the misery of an underclass in the name of opportunity. It is better comprehended in the context of evolutionary biology, as the Earth residents still thought within the context not only of a monogenesis, but of self-identity by genetic affiliation. In this era they had already broadly turned against the concept of racism, and recognized that "Xenos" could experience comparable concepts of mathematics and heroic conduct; yet they imagined that these properties might be inequitably distributed among consciousnesses serving rival biospheres. What a strange juxtaposition! By interstellar coexistence, to contemplate the betrayal, by traditional standards, of every fellow-organism to the most remote single-celled microbe, which is yet more inherently "human" than any other genesis of life could ever be. Yet to imagine that the concentration of wealth among warlike nations, races, clans, or nuclear families would be the ongoing rule of interstellar society! Of course, they did not have the advantage of tutors from the stars, but it is easy to forget that their autochthonous religious heritage was by no means alien to us. When TRAPPIST Monks first surveyed their indigenous heritage, they had no trouble cataloguing comparable concepts of Atman and Brahman, Dao and Holy Spirit as are taught in their own moral philosophy. The humans appeared to have all the makings of a modern cosmopolitan society, yet there was an ongoing obfuscation of their essential nature that prevented them from achieving the self-realization that was their common birthright as thought in the universe. With our more advanced methods of thought transference, it is very difficult for students to conceive of how they could have considered "one person" to be a different and opposed essence from "another person". We have studied the evolutionary basis of this as a genetic principle, but is it inherently paradoxical for a conscious person to hold this philosophy of self? The remainder of this course session will be given over to your essays and mutual commentary. ]
[Question] [ Considering both full water worlds mostly out of water and ice, and rocky planets that just have a bit too much of it - would polar caps form on them if the conditions are roughly similar to modern Earth? Or the lack of large landmasses would turn the whole hemispheres of the planet into one giant Gulfstream due to there being no obstructions for the warmer water to replace sinking cold polar water and equating the whole planet's temperature, much like the atmosphere currents of a tidally locked planet can prevent its atmosphere to liquify on the night side? [Answer] Yes. Polar ice caps would defnitely form, if the world is such the the average polar air temperature is well below freezing. The question is whether the ice would remain in the polar region or drift away and melt. For a deep ocean world, without any shallow geographic features, the waterflow will be very similar to the airflow around it. i.e. Alternating regions of laminar east-west flow, with regions of more turbulent cyclic flows inbetween. [Something like this](https://www.weather.gov/source/zhu/ZHU_Training_Page/winds/Wx_Terms/Flight_Environment.htm): [![enter image description here](https://i.stack.imgur.com/e9mWR.png)](https://i.stack.imgur.com/e9mWR.png) This will mostly keep the polar water just spinning in place, with limited circulation to lower latitudes, keeping the ice cap in place. If however the ocean world has significant underwater geographical features (sunken continents), and especially if some of these continents approach or breach the water surface, the oceanic currents will adopt the large, circulating [Oceanic Gyre](https://www.nationalgeographic.org/encyclopedia/ocean-gyre/) patterns familiar on earth. [![enter image description here](https://i.stack.imgur.com/RO1uT.jpg)](https://i.stack.imgur.com/RO1uT.jpg) With these Oceanic Gyres in place, the polar ice will want to be pulled along with the current, and require either a solid rock foundation(Antartica) or being sufficiently landlocked (Arctic regions) to stay in place. [Answer] The Arctic Ocean has an ice cap despite the Gulf Stream's access through the Greenland and Barrents Seas. As long as the polar surface waters are cold enough for part of the year for [frazil](https://en.wikipedia.org/wiki/Frazil_ice) or ["grease" ice](https://en.wikipedia.org/wiki/Grease_ice) to form, your ocean world can have ice caps. Water planets can be ice-free, have ice caps like Earth's Arctic Ocean, be mostly (a [cold "eyeball" planet](https://iopscience.iop.org/article/10.1088/2041-8205/726/1/L8)) or entirely covered in ice (like [Ganymede](https://en.wikipedia.org/wiki/Ganymede_(moon)#Internal_structure)), and, if deep enough, have icy floors below their liquid surface. Not only can ocean worlds have ice caps, they may be more habitable than those without: > > Traditional definitions of the habitable zone assume that habitable planets contain a carbonate-silicate cycle that regulates $\text{CO}\_2$ between the atmosphere, surface,and the interior. Such theorieshave been used to cast doubt on the habitability ofocean worlds. However, Levi et al (2017) have recently proposed a mechanism by which $\text{CO}\_2$ is mobilized between the atmosphere and the interior of an ocean world. At high enough $\text{CO}\_2$ pressures, sea ice can become enriched in $\text{CO}\_2$ clathrates and sink after a threshold density is achieved. The presence of subpolar sea ice is of great importance for habitability in ocean worlds. It may moderate the climate and is fundamental in current theories of life formation in diluted environments. – [The Ice Cap Zone: A Unique Habitable Zone for Ocean Worlds, Ramses M. Ramirez and Amit Levi](https://arxiv.org/ftp/arxiv/papers/1803/1803.07717.pdf)[PDF] > > > [Answer] There would be two main variables I can think of. Firstly the amount of radiation received by the planet from its sun (temperature). Assuming you take an Earth sized planet orbiting a sun like star then that basically comes down to how far out from the star the planet orbits. Note: there are people on this forum who can and probably have already calculated what happens if you were to arbitrarily increase/decrease the Earths distance from the Sun and the impact on climate. Push the Earth far enough out (e.g past Mars) and it would be a ice ball.) So do a search of the site. Secondly there is the depth of the oceans. If you have large continental sub surface land masses at polar latitudes then depending on the depth of the water covering them and their geography they might interrupt oceanic convection currents enough to allow permanent ice caps to form. But the water level above the continent would have to be shallow, very shallow for this to come into play. If the ocean over the land mass is more than a few meters deep it probably wont be enough to let ice settle in place. So that just leaves Sea Ice! depending on its distance from the sun and its degree of inclination (seasonal period) you could have a water covered world where, during the winter period masses of sea ice form in the extreme polar regions then drift off on the prevailing currents. Get enough ice forming quickly enough and depending on how strong the wind and water currents are you might get temporary floating ice fields forming during winter in the northern and southern polar regions, alternating so that only one pole as ice at any one time. [Answer] ...And from my search online, the results are confusing. I've found a scientific article about atmospheres on water worlds: <https://web.archive.org/web/20180825152625/paoc.mit.edu/paoc/papers/aqua.pdf> It says the following: > > Millennial time-scale simulations yield a mean state in which ice caps reach down to 55° of latitude and both the atmosphere and ocean comprise eastward- and westward-flowing zonal jets, whose structure is set by their respective baroclinic instabilities. > > > But then there are these guys: <https://journals.ametsoc.org/view/journals/clim/19/18/jcli3874.1.xml> And they say it will be essentially the opposite of that: > > The WaterWorld climate is significantly warmer than that observed for the modern reference (Fig. 3). The annual average air surface temperature is 27.5°C, with a shallow equator-to-pole temperature gradient from 33°C in the Tropics to 13°C over the polar islands. Only small areas drop below freezing in winter, and those are over the polar islands—there is no sea ice formed at any time of year. > > > So I guess the real answer is that it can be both and the writer's free to choose whenever his Waterworld has ice caps or don't? [Answer] Simple: You need a region that has a maximum mean temperature of 271 K. Seawater freezes at a lower temperature than freshwater, and we already have polar regions of this very world with the needed temperature. But as the surface is covered completely by water, that’ll be a double-edged sword. Low-lying clouds work to reflect energy back into space and higher up ones help trap it. Water has a low albedo and high emissivity, so it absorbs lots of energy during the day, and loses a good amount of it as well. Water vapour is a greenhouse gas, but water having a high specific heat capacity means that it takes a good amount of time to heat up and cool down. So, you don’t want to place your planet too close to its sun(s). It’s that simple. ]
[Question] [ I am an aspiring fantasy writer, and I wanted to include rideable Wyverns in my world. There will be a magic system in my world, but I still want to make them as scientifically possible as I can. Now, believe me, I did my research (or at least as much as somebody without a degree in physics and biology could do) and I know that creating anything that is supposed to fly and be mount is borderline impossible. That's simply too much weight. But maybe that's the part in which readers would suspense their disbelief. Now onto my notes. So my idea of a Wyvern: * They are tetrapods/quadrupeds. * They walk on all-fours * They are carnivorous * They are covered with colorful feathers. * They have swan-like/snake-like necks. * They have short, normal tails (Without barbs or stingers). * Their legs are short but strong. * They have pterosaurs-like wings, with membrane exceeding to the ankles AND FLIGHT FEATHERS (This and the next point are the ones I'm the most worried about, as I'm not entirely sure whether or not this is even biologically possible) * They are only about 4,5m long (14ft 9in) from the tail tip to the mouth, just as tall as a horse, maybe slightly taller, with a wingspan of 6,5m (~21ft) * They weigh around 60-70kgs (132-154 lb.) * They have hollow bones * They have a special sack in the belly which stores hydrogen to help them fly (they gather it naturally in small amounts by the degradation of inhaled air) * Flight like condors (Mostly glide, with rare big swings for gaining altitude) * Start flying by throwing themselves off the cliffs to gain momentum * Cold-blooded so they bask in sun often * Sexual dimorphism: Females are slightly bigger than males and sport bone crest on the back of the head. * For a few centuries, bred by humans Operate mostly by the reptilian brain, live by instincts, stupider than dogs, rather unfriendly but can be thought respect to their riders. (smaller brain=less weight) Fantasy genre touches: * Special wing muscles: denser but lighter than muscles found in humans for example. * They can support the weight of one unarmored human Do you think this concept can work? Do you have any advice or ideas? Would bat wings be better? (I heard that they offer greater agility and maneuverability, but are not really suited for long-lasting travel.) Would two sets of wings, generate more lift? [Answer] Maximum size for flying vertebrates on Earth Quetzalcoatlus reached 250kg with a wingspan of 10.4m. This is your best basis to work from. [This paper](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0013982#pone-0013982-t001) provides a Relative Failure Force for Quetzalcoatlus' humerus of 1.85 (that is 1.85x it's body mass). This should equate to around 450kg (without accounting for any scaling) as a theoretical biomechanical limit, which allows you a potential payload of around 200kg. [![Relative failure force of humerus of different species](https://i.stack.imgur.com/JwIOw.png)](https://i.stack.imgur.com/JwIOw.png) With a total mass of 450kg, the wyvern would have a [max aerobic performance](https://www.researchgate.net/publication/15014212_From_damselflies_to_pterosaurs_How_burst_and_sustainable_flight_performance_scale_with_size) of 3N/kg, or about a third of what it needs to sustain flight (9.8N/kg) aerobically. In comparison, an albatross' maximum aerobic performance is ~6.5N/kg although they often use cliffs to launch. Your wyvern would also require more than twice as much energy to launch per kg (at 322 Watts/kg compared to 151 Watts/kg for an albatross) which works out at double the total flight energy requirements of Quetzalcoatlus. At 450kg, the wing load would equate to 34kg/m2, the maximum for birds is taken to be 25kg/m2. With a payload of 70kg, the wing load becomes a more reliable 24.25kg/m2 which might be plausible. Plugging this back into the original equation gives you a max aerobic performance of 4.3N/kg, which is at the lower end of what is measured for Kori Bustards and is probably pushing the limits of what is achievable on earth. Similarly to what someone else mentioned, if your world is a clone of earth, then like horse-racing, you may need smaller, lighter jockeys to be your dragon riders. Increases payload capacity Lift (and drag) increases linearly with air density so doubling the air density would halve the amount of power required to fly, although I'm not sure whether this has an effect on wing loading. This is also small enough to not have a neglibile impact on anything else. This would double the partial pressure of oxygen (as well as other gasses) so respiration will me slightly easier (and potentially humans would exhaust slightly less easily) but it shouldn't produce any health effects. Alternatively, Decreasing surface gravity by just 20% would give you a launchable total mass of 400kg, or a wing load equivelent to 238N on earth, if you needed heavier mounts. I'm not sure whether the maximum wing load of pterosaurs would be the same as birds since launch using their hindlegs, whereas pterosaurs, [launch using their forelimbs](https://www.palass.org/careers/phd-opportunity/phd-pterosaur-flight-biomechanics-how-did-largest-airborne-animals-get-ground). It may be that pterosaurs could launch with higher wing loads than birds although. The wing load of an albatross, Bustard, and Azhdarchid is around 12, 8 and 18 kg/m2 so it seems that pterosaurs were at the upper end of bird capabilities already. Adressing your flight adaptations: Some of the adaptations you listed would actually impede your creatures flying capabilities. Hydrogen sacks or other gas equivelents would increase drag by a significant amount for a negligible increase in lift. It is also very difficult to store hydrogen due to its reactivity. Flight feathers are also a bad idea as they are a large contributor to bird size limits. [Flight feathers must be shed periodically](https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1000132) but in doing so, flight capabilities are compromised. Soaring birds often extend their molting periods over 3 years or so instead of the typical annual cycle. Some birds may also shed all their flight feathers at once and be rendered temporarily flightless while they grow back. A membrane wing with pterosaur anatomy negates this limitation. It doesn't mean your dragon can't have feathers, just that they should not have flight feathers like birds. Additionally, a slower metabolism would be a disadvantage. Faster bird metabolisms are linked to their superior flight capabilities over mammals. Hollow (pneumaticised) bones, long necks, carnivory, short tails and quadrupedalism are all already pterosaur adaptations so no changes there. The one exception is that azhdarchid necks are long but very very stiff. In your wyverns, you could just give their necks more flexibility but reducing the length of the vertebrae and increasing the amount of them may help. Even though these wyverns are larger than you expected, at 2.5m at the shoulder they're a little taller than a horse but if you want them to be shorter whilst still obeying physics, you're going to have to reduce gravity even further or create a super-dense atmosphere that generates enough bouyancy to offset the wing loading. The win is that the azhdarchic base actually works out around 4.5m long. The width shouldn't make too much of a difference since they walk with their wings folded - we also know from pterosaur tracks that they most likely walked with their limbs under their body. The [wings are very important](https://royalsocietypublishing.org/doi/10.1098/rspb.2011.1529) so I would not recomend reducing them (or the shoulder height unless you give them a sprawling posture. Azhdarchids had huge but very pneumaticised heads so a more stereotypical dragon head should be fine without effecting the weight distribution too much. The only important factor here is that quetzalcoatlus had [very weak jaw muscles](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0002271) so if your dragons are feeding on more robust or volitile prey, the front end-mass will increase with musculature. The flexible neck will likely require more musculature already but looking at bird necks, I don't think this would make much difference. Since your dragons are semi-domesticated, it probably works best (And safer for your riders) if their head musculature is kept to a minimum so no issues there. Fun fact: Snakes actually have next to no neck! They're all torso. If the giraffe-like posture is a no-go, then you could increase the length of the rear legs to bring the spine into a more horizontal position. I assume you may shorten the neck anyway so their posture would adjust to suite. As for more efficient muscles, lightweight bones, etc. I think it would cause more problems than it solves. I think your creature would do fine already. The problem with flight isn't so much the energy requirements, it seems to be [more to do with wing load](https://jeb.biologists.org/content/jexbio/130/1/235.full.pdf) and the limit to [how much weight the actual wing bones can support](https://advances.sciencemag.org/content/5/1/eaat4269) (and how long they can grow). As well as the biological factors such as molting flight feathers. One last link that may be of interest is this [paper on the pteroid bone](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2842769/). Conclusion In summary, your wyverns should be fine, if a little bigger than you were expecting - weighing 250kg with a carrying capacity of 70kg on earth, 105kg at 90% gravity and 150kg at 80% gravity. Some of your unique adaptations would be detrimental to its flight capabilities. Whilst your wyvern is feathered, the feathers are not primary flight feathers and would function more like pycnofibres of pterosaurs. It may have some streamlining feathers over the wing membrane to increase the airfoil effect and some feathers may be used to add rounding to the wing tip although the lift would be generated almost exclusively by a wing membrane. [![Your basic wyvern body plan](https://i.stack.imgur.com/N3Wx4.png)](https://i.stack.imgur.com/N3Wx4.png) [Answer] Your wyverns are giant hoatzins. [![hoatzins](https://i.stack.imgur.com/Iom4u.jpg)](https://i.stack.imgur.com/Iom4u.jpg) <https://en.wikipedia.org/wiki/Hoatzin> Using a neotenous hoatzin gets past the hardest part of your requirements: a flying quadruped. Hoatzin chicks have claws on their wings and use them with their legs to walk like a lizard. <https://www.insidescience.org/news/baby-birds-use-wing-claws-climb-through-amazon> > > In a tank of water, the chicks swam by moving both wings together in a > pattern resembling the breast stroke. Such simultaneous wing motions > are the norm for birds, although most employ them for flying rather > than swimming... > > > The most interesting findings came when the researchers placed chicks > on a slope covered with a towel. The bird's progress up the slope was > slow and halting, and it sometimes took a couple of tries before the > wing-claws succeeded in grabbing the fabric. But the basic pattern was > clear: right wing, left foot, left wing, right foot. Hoatzin chicks > walk like four-legged animals, using their wings as front legs. > > > Wyverns are giant hoatzins that have kept their claws. Another tough one is the hydrogen gas bag. But hoatzins are ruminants and hydrogen production via fermentation is totally legit. Yeah that's right. Ruminants, like cows. But you want them to eat meat. That is fine. They do, when they can get it. They eat anything. They are bloated colorful flying goats, these wyverns. Awesome colors - that is hoatzins. Long neck; hoatzins got that. Sunbathing. sure. But not because they are cold blooded. Because they are covered with parasites and getting good and hot cuts down their numbers. - [Answer] There are problems 1. You can't be a cold blooded vertebrate flyer, you can't maintain enough warmth in flight to get anywhere without a high metabolism. wings are too effective at cooling. Also flight is high energy demand, so that s another reason you will not see it in a cold blooded animal (well not one that weights more than a few ounces). Also feathers would be a big disadvantage to a an animals that basks, or to a an ectotherm in general. Feathers are insulation that evolved after endothermy as a way to help maintain high body temperature from internal heating. Note plenty of endotherms bask, especially one that undergo torpor, so you don't need to justify basking with cold bloodedness. 2. The buoyancy you get from hydrogen gas is not worth the space it takes up. You need a HUGE volume of hydrogen gas to lift any appreciable mass. A 6ft diameter sphere of hydrogen gas only offsets about 8 lbs. 3. No horse sized flyer is carrying a human, Quetzalcoatlus the largest creature to every fly might be able to carry a human. You will need to give them a significant sprawl (ala game of thrones dragons) to get horse height. A long distance flyer needs a wingspan comparable to a fixed wing aircraft. Don't bother with 4 wings there are no vertebrate fliers with 4 wings. It is worth noting pterosaurs has fur like feathers, and [bat winged dinosaurs](https://en.wikipedia.org/wiki/Yi_(dinosaur)) did exist so most of this is possible. Both groups are extremely close to what you want (all the features below), fulfilling most of your requirements. > > They are tetrapods/quadrupeds.\* > > > They are carnivorous > > > They are covered with colorful feathers.(well protofeathers) > > > They have swan-like/snake-like necks. > > > They have hollow bones > > > Sexual dimorphism: Females are slightly bigger than males and sport > > > bone crest on the back of the head. > > > \*Yi are bipedal but they are also small, I could see a a return to quadrupedal with extreme sizes. Note bat like wings give you your smallest possible wingspan, so you may want to stick to that. [![enter image description here](https://i.stack.imgur.com/DEHnE.jpg)](https://i.stack.imgur.com/DEHnE.jpg) [Answer] Having flight feathers and wing membranes in the same place would likely make the wing work like a wedge, which doesn't seem aerodynamic. However, if the membrane and flight feathers were in different positions along the wing, there shouldn't be many problems ]
[Question] [ As a layman, I was shocked to learn that LASERs in real life are much more dangerous than Hollywood portrays. As I understand it, you can get permanent eye damage from a strong enough laser, even without looking directly into the beam's path. Knowing this, as someone who likes to write Fiction, I find myself at a quandary. In order to have a laser weapon truly capable of slicing metal, for example, the wielder would need serious eye protection. Battles in space, with people shielded from exposure, might not be affected, but such constraints would seem to make ground combat with handheld devices very impractical. Just about everyone likes how lasers look, myself included. But I also like to inject at least some realism into my work. * If I want to go down a more realistic path in weapons design, are there existing writing devices or explanations I can use to include high-powered lasers in atmospheric/ground combat situations that could pass for realism? As I understand it, even the beam of a laser itself would be hard to see - if at all - in space, which was also quite disappointing to learn. It makes me wonder if such issue is the reason lasers are much less common than "Phasers" in Star Trek. My instinct is to make up some fictional technology in arbitrary fashion, which is how I assume most Science Fiction explains this away, if the question is even posed. But I am a novice, and quite ignorant to the vastness of SciFi, so I would rather ask people who know a lot more about it. Thank you Relevant video... "Laser Safety: Chapter 2 - Myths and Misconceptions of Lasers" <https://www.youtube.com/watch?v=HvbXlx-WH9g> "Lasers in the Movies" <http://laserstars.org/amateur/movies/myths.html> [Answer] The Good, the Bad, and the Ugly Lasers are, indeed, uber cool. But it seems to me that people haven't used "lasers" (by specific name) in commercial fiction for a while. Am I wrong? * It's true that a low-power laser, one that won't even heat your fingertip, can blind you. However... whether or not looking near the laser (some number of degrees off the axis of the beam) is damaging has more to do with the focusing optics and intent of the beam than it does the beam itself. A poorly focused beam spreads a lot of, shall we say, optical noise. A well-focused beam does not. * It's true that no laser of any wavelength is visible as a beam. If you think about it, no light at all is visible as a beam. What you're actually seeing is reflections of that light off of dust, humidity, etc. (E.G., search lights.) The stronger the beam, the easier it is to see. In other words, you're seeing feral, uncontrolled photons that are no longer doing what they were expected to be doing — such as burning a hole in some deserving villain. As the power level increases in an atmosphere what you could begin to see is plasma. That's hot, kinda burning gas. In a vacuum, you'd never see the beams. (Thanks for lying to us Hollywood!) `everyone likes how lasers look` What you mean by this is "everyone likes how Hollywood presents lasers." Hollywood doesn't reflect the truth of lasers at all. Hollywood (generally) presents a bright, easily seen, pulse. Nothing about that last sentence has anything to do with a laser — and that's the problem. If you want realism you're forced to walk away from what Hollywood's done to lasers completely. And that's probably why I don't see a lot of scifi anymore that uses the word "laser" in the context of a weapon (or maybe I'm just not reading the right books). What I see more often is a cool Proper Noun (aka blaster, phaser, disruptor...) that means "energy weapon," and what "energy" that could be is left to the imagination of the reader/viewer. Personally, I like "death ray." So, if you're trying to inject realism... * A laser "pulse" is complex. Think of it this way: you turn on the laser, count to ten, then turn it off. For there to be a "pulse" requires your enemy to be more than ten light-seconds away. That's more than 3,000,000 km distant. You can't see them. You can't detect them. But you shot at them. Yes, you could fire your laser for a micro-second (a 3 km pulse) or for a nano-second ( 3 meter pulse) or for a femto-second (3 mm pulse), but you also need to pack all the energy you need to damage your opponent into that smaller period. The math gets ugly. One watt = one joule per second. Let's say we want the [Tsar Bomba](https://en.wikipedia.org/wiki/Tsar_Bomba) in a femto-second laser. 240 peta-joules (240x1015) in a femto-second for a whalloping 240x10240 equivalent watts. (\cough\) Yup. To be fair, I'm having fun overstating this. You're generating 240x1015 joules. Period. Tsar Bomba in a femtosecond. But it sounds fun the other way because it's a mega-[Kardashev](https://en.wikipedia.org/wiki/Kardashev_scale) civilization type of thing. Sorry, I couldn't resist. But if you could turn that laser on for a full second... that's what you'd have... the luminosity of galaxies in a single one-second pulse. * A visibly traveling laser "pulse" is... well, it's laughable. Fun to watch! But laughable. Even if you fire your Tsar Bomba laser with a 3mm pulse, that pulse is traveling (in a vaccuum) the better part of 300,000 km/s. That means your target must be more than a light-second away to have any hope of actually seeing the pulse — which you couldn't anyway because you're in the vacuum of space (which isn't completely empty, but it mostly empty enough that I doubt you could see anything). * BTW, that second you're spending watching your pulse sail through the universe? Yup, your enemy is using that time to send something like 1015 pulses right back at you. While you were having fun watching a single pulse blow the nose of his ship off, he blew you up, vaporized your planet, and moved the timetable for your sun going supernova by a couple of eons. I've always thought it was funny watching Han Solo slowly pulling the trigger and sending a couple of blasts at the approaching Storm Troopers. I mean, really! We've had Uzi technology for a while now! Just hold down the trigger, Han! And just to make things interesting... * The battery/power-source needed to operate a death-level laser for any sensible period of ground combat time is, in this day and age, detrimental to the use of lasers in ground combat. However, if you use [Clarkean magic](https://en.wikipedia.org/wiki/Clarke%27s_three_laws) to handwave the power source (see reasons to do this above), then you can use the same magic to handwave the optics, and the issue of blinding everyone within 10 meters of the target is a non-issue. Remember, feral photons are undesirable, they represent lower efficiency. Lower efficiency means you need a stronger power source to be sure a lethal dose of photonic wrath is dealt to your opponent. * And while we're on the subject of optics. The basic problem with photonic weapons is the need to focus. It's the difference between burning a hole clean through the villain and giving him (and everyone around him) a nice tan. All kinds of cool juju has been used to deal with the problem of having to focus the beam (my favorite is oil-lens optics, as if the laser wouldn't boil the oil...). If your laser carbine is focused to 250 meters, then the further away from 250 meters your opponent is (closer or more distant!) the more it's a nice tan and the less it is violent photonic death. Same problem with ships, just much, much worse. * Getting back to power generation, power generation on a ship is problematic, too. You must either have big mother-hubbard batteries that are breathtakingly dangerous to have around (what happens if their laser hits your battery before you can discharge your laser? Bad things...) or you need some form of magical power-on-demand, like chaining up a bunch of dynamos until you have peak power and then spinning them back down or some such. That could be cool, it means there's a measurable amount of time between shots (spinning up the chain). No more gatling lasers, but realism! * Lasers have two traditional nemeses — (1) ablative armor. Granted, ablative armor is kinda useless if your opponent can get a second shot off, but if it takes time to get to that second shot, then maybe the armor was worth it... and (2) people have suggested that mirrored armor could be good, too, but that depends on whether or not the mirroring material on the back of the proverbial glass can withstand the heat generated by photons that are not reflected. Theoretically, a perfect mirror (perfect mirroring and perfect glass) could reflect a laser of any power level. But, perfect's hard to achieve. My point is that it's not that hard to develop ways to avoid laser damage. I'm favoring squirting a million metric tons of sand between your ship and your opponent's. Your missiles will wreak havoc while your enemy is turning all that sand into glass. (Yeah, yeah, yeah... it's impractical to haul around millions of metric tons of sand. It's impractical to have all those batteries, too! Work with me, people!) BTW, and not completely off the topic, the nature of lasing is that it can't really be done at radio wave frequencies — yet. I mean no one thought the inside of a light bulb could be frosted until Edison did it and no one thought a human could run a mile in less than four minutes until Sir Roger Bannister did it and the the mathematical band-aid known as "dark matter" is believed to be real by almost everyone under the age of 25 despite a total lack of non-mathematical evidence... My point is, I'm not a fan of "can't be done." Today's "can't be done" tends to become tomorrow's "eureka!" Therefore, I recommend you ignore reality and write a good story for which Hollywood would be willing to pay you beaucoup bucks. If the majority of book-buying people preferred reality, science fiction as a genre wouldn't exist. And in the end, you'll be laughing all the way to the bank while a handful of people still working 9-5 jobs grind their teeth and say, "lasers don't work that way!" Edit: I wrote all that a long time ago, but I forgot to mention one important thing: someone's ability to see the laser in space is pretty darn impossible. It's not so bad when it's continuously on and in a medium (aka, filled with dust) that allows photons to become feral, but in the vacuum of space, it's a whole different matter. Light travels at, well, the speed of light! That means that the target would never see the beam. All they'd see is the result, hopefully a whole lot of burning metal. People on the death-sending ship (they that fired the laser) also wouldn't see anything unless a whole lot of feral photons were reflected backwards... in space.... People might see something (if there were enough dust to cause feral photons) as the beam passed — but it's just easier to understand that pretty much no one would see anything. Such is the nature of lasers. [Answer] You actually answered your own question: # My instinct is to make up some fictional technology in arbitrary fashion Unless your story writing demands 100% rigid science compliance, you really don't need to justify laser weapons or even delve too deeply into how they work. If you write some kind of energy beam weapon fired from a gun-like device, your readers will simply assume that this is part of the technology of the fictional world they're delving into. If your writing style would like to give a nod (and a wink) to realism, then you could very easily do this. You'd want to avoid the actual science (because we don't yet know how to pull off such a weapon), but you could address some of the issues that you bring up in your query. For example: vision damage is a real thing with lasers. This is why serious laser users (medical field, science, and engineering) obtain the eye protection appropriate for the kind of laser they're using (one goggle does not defend against all lasers!). Some lasers are invisible; others produce extremely bright beams than can light up an entire room. You could very easily provide your storm troopers with helmets that integrate a variety of eye shields. You could demonstrate your knowledge by integrating into the narrative some kind of error or malfunction -- maybe a new soldier taps the wrong button and brings down the wrong shield and is blinded. Maybe the commander orders his troops to bring down a certain shield, because the enemy are known to use weapons in that range, but surprise! The enemy has switched its own weapons' wavelength, now rendering our heroes vulnerable. You could also develop weapons that, along with the destructive core beam, also emits a kind of shielding beam that eliminates the need for eye shielding. It might in some way cancel out or serve as a waveguide for the beam, at least close to. Anyone nearby can see the beam but be protected from vision damage. Farther away, the shielding might degrade, because, who cares whether your enemy's eyes are damaged or not! ]
[Question] [ Thundercats 2011 was great. I mean, it even had Thanos and infinity stones before it was cool. Such a good remake simply couldn't survive in final-stage capitalism, as those who worked on it didn't sacrifice quality to more efficiently promote plastic landfill. Well, at least my secret network of spies across the WWW managed to track down one of the art directors (well, [his DA page](https://www.deviantart.com/dannortonart)), here I found something interesting I didn't even notice while watching the show. [![enter image description here](https://i.stack.imgur.com/QNSOd.png)](https://i.stack.imgur.com/QNSOd.png) [![enter image description here](https://i.stack.imgur.com/JB4tH.jpg)](https://i.stack.imgur.com/JB4tH.jpg) See where the wings are? Well, I think this image shows it even better. They're closer to the waist. In paper, this solves problems with balance, but people who praised this idea forgot that now these bird people have a big, rigid bone in the area of their stomachs, making basic things, like bending down to grab something, an impossible task. I have very, very similar creatures in my world (please don't sue) and I haven't actually thought about this... HECK! My two other six-limbed creatures, centaurs and dragons avoid this anatomical problem. Centaurs have their human body where normally a horse's neck would be, which is pretty flexible; and dragons are still rather snakey, despite their bigger chests, plus their forelegs have been dialed down to reduce the TPK-capability of an all-out "paw-paw-bite-and-set-on-fire" pounce. Bird people aren't particularly snakey, neither are they short kings like the aarakocra. I still wanted to keep the bird people's weight low, because I won't go through the same headaches, estimating dragon flight-capability had brought. Alexander Zass, the guy who could bend steel, was only 167 cm and 80 kg. So I guess we will be safe with a total mass of 70 kilograms for bird people, plus what Marden said that around 20-25% of a bird's weight is their flight muscles, we get either 56-52.5 kilograms to make the rest of the body. As I said before, I'm more lenient with height (they can be taller if that helps the issue), but weight is still a constraint. Sure, they aren't supposed to be strong, yet taking away even more of the pecs sounds like a bad idea, as they still need to do things like wielding weapons and ~~coffee~~ covfefe mugs, but then the lengthening of their ribcage is inevitable and I am Iron Man. But seriously, how can I keep these bird people out of the uncanny valley while also giving them enough flight muscles without compromising their ability to do ab crunches? [Answer] Hip joints I should preface this by saying I'm not by any means an expert on birds' anatomy. That said, if you feel the need to keep some scientific accuracy so that these bird folk have a rigid sternum in their mid section, a possible way to circumvent their innability to bend forward would be setting their hip joints further apart. Just like in goold ol' regular birds, this would allow them to bend down in more of a squatting fashion if need be. It wouldn't really solve the problem of the ab crunches, but I believe it might improve their mobility as long as you allow for some hip torque. [Answer] ## Your birds just need prehensile feet Forget about making rib cages flexible, they don't need to bend over, they have muscular legs and good enough balance to lift whatever they need with their feet. [Answer] The wings could be anchored to something like a second set of shoulder blades that attach near the bottom of the ribcage. This would allow for an open area between the ribs and pelvis but not quite as big as a human's. Some birds barely have a separation at all between ribs and hips. They make up for it with flexible hip joints and the ability to fly. Alternatively you could extend the pelvis upward with an outcropping on either side for wing joints to fit into. This may put your wings too low, or maybe not. Those of us who are human get a couple of less connected ribs that don't come all the way around like the rest. Your birdfolk could have even more of those to anchor your extra bones on. In the end though, who's gonna check if the fictional species you created is biologically accurate? Give those bird people wings. [Answer] I think this image from the [answer](https://worldbuilding.stackexchange.com/a/108606/49261) by [Len](https://worldbuilding.stackexchange.com/users/46557/len) to this [Anatomically correct multiarmed humanoids](https://worldbuilding.stackexchange.com/questions/74254/anatomically-correct-multiarmed-humanoids) SE question is probably what you're looking for. [![enter image description here](https://i.stack.imgur.com/HFWp9.jpg)](https://i.stack.imgur.com/HFWp9.jpg) Obviously the lower pair of arms become your wings. Just scale your bird men accordingly to achieve the height you want. Naturally the wings are going to be longer & the bird sternum & its muscles (which should be somewhat bigger than human pecs) replacing the lower ribcage will provide a different 'chest' shape in the upper body area than shown. You probably want to relocate the wings shoulders back a little closer to the spine than normal shoulders to help avoid the two sets of limbs interfering with each other. But I don't see a problem with waist flexibility in this skeletal structure, hope that helps. [Answer] *Switch out the torso* I like the answer by Pelinore! But also, this might be helpful: <http://www.sciencepartners.info/module-6-birds/bird-anatomy-bones-muscles/> There's a nice diagram in there of both bird and human skeletons, that shows how both bodies work and you can use your imagination to combine the parts you want. What I imagined changes the skeletal structure away from the pics you offered though. Their torsos would be different. In short, it might be more realistic to have a bird torso with human appendages, rather than a human torso with bird appendages. [Answer] ![enter image description here](https://i.stack.imgur.com/Xaf9Q.jpg) What I think a lot of people are forgetting about is a keel, it is vital for flight, it is where the birds flight muscles connect. I also am working on hexapodle bird aliens and I have also ran into these problems in the past. I have settled on a longer abdomen with shorter yet more stable legs, the type of legs the elites in Halo have I forgot the name for it. This will balance out the body as you bird will have to deal with the weight of the wings that have been attached to its humanoid body. So lets say lighter bones (obviously) longer torso to allow a normal human ribcage then as we go lower the keel for the wings and below you can shove whatever alien organs you want and then the legs which will be those weird three jointed legs that most four legged aninals have in the back. So we have mostly everything set but theirs a few slight problems. Without proper feet or feathers, your bird creature will not be able to traditionally swim like a human does and will have to use its wings or if its adapted for it, its feet. Also, your creatures head will be slightly lowered during flight due to the wings being placed lower on the spine and will most likely fly like a secretary bird whos legs are all poking iut at the end due to there length. [Answer] ## Add an extra joint to the wing By adding an additional segment to the wing, you can have the flapping motion start off to the sides, where the arms and body won't get in the way. If you'll forgive the crude drawing, it would look something like this: [![enter image description here](https://i.stack.imgur.com/DWeK5.png)](https://i.stack.imgur.com/DWeK5.png) The main joints are highlighted in red. Note that the first segments of the wings would not be positioned directly back, but would be angled towards the sides to allow for more freedom of movement for the wings proper. These first segments would probably have an unusual bone setup to allow them to easily lock into place with little muscular effort. the first "elbow" joint would probably be very large and bulbous to support flight muscles. [Answer] Flying skills required ? Opening: "I still wanted to keep the bird people's weight low, because I won't go through the same headaches, estimating dragon flight-capability had brought." Weight is an important consideration, but wing shape and wing span are also relevant. Correct anatomy would depend on the flying skills you want to give these creatures. When your scenario is involving say 50kG body weight and actual flight in a planetary atmosphere at Earthly G-forces, a wing span as depicted will be insufficient to take off from the ground, especially when helmets, armour and weaponry are needed. You'd require very big muscles for take off, allowing for hummingbird like wing speeds. There are other ways.. a creature like this could jump off a cliff or tower, and proceed gliding considerable distances, make use of thermals. A wing suit type of flight would be feasible, even with the above proportions. Gliding could be made easier and more agile, with a different set of wings, having less prominent feathers. Rather a smooth, wide surface, like seagulls have.. the gliding action does not involve much energy, so the muscles can remain small and the wings could be attached to a large, solid waist bone or "waist shoulder" or "hump shoulder" in some way, it should not require too much muscle strength during flight. Note some muscles will certainly be needed to fold the wings, as you show. The support bone may need to be hinged, to fold and unfold the wings. ]
[Question] [ I'm working on a novel that takes place in a fictional universe which involves creatures with long forelimbs and short hind limbs. Some of these creatures includes amphibians , reptilians and mammals. I want to know what type of environmental factors could lead to this type of evolution.![enter image description here](https://i.stack.imgur.com/FLgNP.jpg) [Answer] First I want to point out that we see on earth a large diversity in limb length, but almost no diversity in number and arrangement of limbs. It seems that evolutionary forces can change limb length very easily even when other things are very hard. If most of the mega fauna have a similar proportions of limbs, then you would suspect convergent evolution rather than a single long-forelimbed ancestor. The most common arrangement in real world animals is that the front and back limbs are similar lengths, especially if all 4 are used for walking. Think horses, cats, and lizards. Since long fore limbs are the exception, lets look at why that exception pops up. There are three main groups of long forelimbed creatures: ### Bipedal This seems to be the most common. When forelimbs are used for primary method of movement like flight or climbing, then hind legs are often short. Flying birds often have wings that are much longer than their legs. Look at the long, gangly arms of gibbons, orangutans, and sloths. There are exceptions. Most lemurs have longer legs than arms, and some flying birds (like storks and flamingos) have long legs, though many times their wings are even longer. ### Partially bipedal Forelimbs are used for walking sometimes so must be long enough to touch the ground while remaining partially erect. There are not many examples of this. Gorillas. ### Tallness Long forelimbs let the head be high up in the air. A giraffe's forelegs are only a little longer than their hind legs, but they are longer. This seems to be more common the fossil record. [Brachiosaurus](https://en.wikipedia.org/wiki/Brachiosaurus) type dinosaurs are the most extreme example, but it's also seen to a lesser extent in ancient mammals like the giant ground sloth. It's pretty much only a herbivore thing. Carnivores don't get as much use out of tallness since they don't hunt trees. ### What environments requires your to be either bipedal or tall? You have huge, continent spanning forests where heavy, toxic fog periodically seeps out of the ground. Creature must either be tall enough to breath the good air above the fog, or nimble enough to scamper up the trees. You could imagine that most successful creatures are either tree swinging climbers, or tall tree eaters. [Answer] As the other posters said, the long forelimbs are not at all uncommon, and they covered it well. The short hind limbs are more unusual. A reason they would have evolved to be short is that there was a strong selection pressure during their evolution to increase their size. With increased size comes the issue of blood transport to the brain. Take giraffes, for example. Their hearts pump ~150bpm at rest just to keep their blood pressure high enough to supply their brains with blood all the way up there. Even still, when they are in an upright position, the blood vessels in their legs are constricted to prevent gravity from making the blood pool in the blood vessels in their legs. When they bend their head down to the ground to drink, all of the blood vessels in the legs dilate. If they did not, then their high blood pressure in addition to their brain being below the bulk of the blood and being drawn down (up into their head) could cause the blood vessels in their brains, which are designed to encourage maximum flow of blood to the brain, to burst. Now imagine an animal that does not need a long neck. The same problem could still occur in a 3m tall Ape, but if the selection pressure was on, for example, arm strength, rather than head height, then they may evolve to keep the elevation of their heads to a minimum while allowing for the maximum size of the arms could very well result in the picture you posted here, if the animals are gigantic. This also may explain it if they appear to prefer walk on all fours rather than be bipedal [Answer] I want to echo what the other contributors have said: limb length is extremely variable in animals and while you might get some animals or even entire clades with forelimbs longer than hindlimbs you will get just as many species for which fore- and hindlimbs are equal in length, or forelimbs shorter than hindlimbs. Hyenas and Homotherium both have forelimbs that are longer than their hindlimbs, this is thought to give them a stride that is energy efficient and gives them great endurance for long-distance chases. Hyenas in particular can run for hours without tiring. Giraffes may also fall into this category to some degree, in addition to being browsers. One common group that have longer forelimbs are high browsers that use their forelimbs to reach branches. Chalicotheres are one example, as are gorillas. Sthenurine kangaroos don't have forelimbs longer than hindlimbs, but their forelimbs are really long. Brachiosaurus has forelimbs longer than hind limbs and this is thought to be for a similar reason, even if its hands aren't prehensile. Gibbons have forelimbs that are much longer than hindlimbs, mostly because of their brachiating method of movement through trees. Sloths too, kind of. Bison don't exactly have forelimbs longer than hindlimbs, but they are front-heavy due to their hump. This allows them to pivot and turn really quickly so they can always keep their horns pointed at an attacker. Long forelimbs could possibly do the same job. One reason why examples are rare may have to do with the functional problems that long forelimbs put on an animal, some of which hindlimbs do not. First, having unequal forelimbs and hindlimbs means the two set of limbs have to have different stride rates, which can be somewhat inefficient because the limbs get in the way of each other. This is why hyenas lope. Secondly, long forelimbs can make it harder to bend down to drink (exhibit A: giraffe, note how the forelimbs are more splayed than the hind limbs) [![enter image description here](https://i.stack.imgur.com/2XnXH.jpg)](https://i.stack.imgur.com/2XnXH.jpg) This is much less of a problem if the two sets of limbs are of equal length, or the hind limbs are longer than the forelimbs. ]
[Question] [ So. our boss is kinda... nuts. His current pet project is to create a device that can play his [theme song](https://www.youtube.com/watch?v=7qJrFqzrgU4) whenever his location is revealed to someone within a 50 meter radius. Naturally, he outsourced it to us. * The device has to play the song in high-quality and loud-enough to drown out gunshots and explosions within 50 meters. * The device should be resilient to all kinds of damage. * The music has to follow the boss around. * The boss also requested that the music shouldn't appear to originate from the boss himself. * It has to play on land and in water. It doesn't have to play in vacuum. And now, we outsource it to you. How could a device fulfill the criteria in the list? [Answer] A very smart long range drone outfitted with a sound laser Sound is kind of similar to light in a few aspects, and one of the aspects is that it usually functions as a wave, but it can be directed in a tight beam, a sound laser, if you will (or, simply just [Soundlazer](https://www.kickstarter.com/projects/richardhaberkern/soundlazer) if you want to see it in practice). Such a drone could be clear of the area, but be able to fire the beam of sound directly into the protagonist's / antagonist's ear during plot-critical moments. This also solves the problem of playing over explosions and gunshots - directed sound doesn't need to be blasted so everyone in the radius goes deaf. As for water, that's where the intelligence comes in. Water refracts and messes with sound, kind of similar to how it does with light (another similarity), but if the drone is built well, it should be able to determine the acoustics, compensate for the adjusted speed (sound travels faster in water) and beam in the music anyway. Something like [this](https://www.youtube.com/watch?v=B_MW65XxS7s). [Answer] A small legion of tiny drones (as in really tiny) that fly around, land on the people facing your boss and take position behind the ears, on the skull. There they will send the music by vibrations through the skull. [Answer] The problem is simpler once you break it up, We can break this one up into 3 parts and solve them separately. First part, is to limit the audible range as 50m, this can be done, with a force field generator placed inside your boss' pocket, It generates a bubble of force field with an effective range of 50m, and can be configured to decrease or increase the range. This bubble is unaffected by any kind of EM changes in the environment and works fine on both land and water. Second part, noise cancellation, remove any noise from the environment within the bubble, for this, there are a swarm of nanobots flying inside the bubble, they identify and drop themselves on ears of other people, or on microphone receivers or other such things and create a force field bubble of their own around the listening piece (ear or mic) and create a noise cancellation field, thus removing any unwanted explosion sounds. Third part, play the theme song, the same nanobots will play the required theme song in surround sound, onto the listening piece, taking a cue from the device placed inside boss' pocket to judge the distance and loom over the sound accordingly as the boss moves around. Though you have outsourced the problem to us, we only provide the design specs in the allocated money, implementation is up to you. ]
[Question] [ This question already has answers here: [Anatomically correct pixie](/questions/48874/anatomically-correct-pixie) (5 answers) Closed 4 years ago. There are many questions and answers regarding giants and how to scale up human anatomy on this website. (larger bones, better lungs and heart, lower body temperature, tighter skin at the feet, etc...) What does it look like the other way around? Let's say specifically that you could apply certain evolutionary pressures constantly for a period of several million years on a group of human beings, selecting for a smaller size while keeping a human level of intelligence, and then later on for flight. What does the anatomy of such a species look like? For example, Would they have bat wings? Or feathered wings? Could they keep their thumb, index and middle fingers short, with the ring and pinkie fingers elongating to form the wing so they could have functional hands still? How does the square cube law affect their anatomy? Do they have a very high metabolism and need to eat very often like shrews? What about their intelligence? I have read somewhere that birds have evolved more tightly packed neurons than humans to maximize intelligence with the smaller, lighter brain required for flight. Is that possible with human beings as well? A ton of questions here but these are just examples of what I am looking for. To summarize, my question here is: what does the anatomy of a 10 inches tall or so, flying, human-descended species look like? If the format of my question is wrong, please tell me and I will fix it as this is my second time asking a question on this website and I am unsure of how to do this properly. Thanks. [Answer] Let's not use the limbs as wings, aesthetically it just doesn't look like a "fairy". Let me suggest the [flying lizards](https://en.wikipedia.org/wiki/Draco_(genus)) work around instead. [![enter image description here](https://i.stack.imgur.com/XuXn5.png)](https://i.stack.imgur.com/XuXn5.png) As you can see they've extended their ribs & used them instead of their forelimbs like the bat, here's a look at the skeleton. [![enter image description here](https://i.stack.imgur.com/6UN4S.png)](https://i.stack.imgur.com/6UN4S.png) 1. Imagine your flying lizard has hair (or is a flying mouse) & evolves a long fringe of stiff bristles along the edge of its 'wings' giving more surface area (even if it does have gaps). 2. Now that the hairs evolve to be flatter & begin to merge into a single sheet of thin stiff [keratin](https://en.wikipedia.org/wiki/Keratin) (the stuff your hair & fingernails are made of). 3. Over time the skin flaps recede & the keratin wing surface expands (less flesh to provide blood flow to, has to be an evolutionary advantage in that). 4. The [intercostal muscles](http://igbiologyy.blogspot.com/2014/04/151-ventilation-role-of-ribs-and.html) associated with the ribs in question develop more strength & shift anchor points as needed & the position of the extensible ribs they're anchored to slowly shift further back & around to a more traditional position for fairy wings. 5. Once they start gliding you've all the same evolutionary pressures as birds & they evolve many of the same evolutionary advantages for flight birds have (higer neuron count for smaller brains with the same intelligence & denser honeycombed bones etc). Now imagine it was a miniature human instead of a lizard & there's your fairy. If we use only 2 pairs of ribs we can give it the double wings of most insects & a really thin colourless keratin wing can look just like an insect wing. They'll appear to have two less ribs than a normal human of course. That covers the basic morphology & how they got there. Instead of 'bat wings', they'll have scaled up insect wings with [Keratin](https://en.wikipedia.org/wiki/Keratin) serving in place of an insects [Chitin](https://en.wikipedia.org/wiki/Chitin) & the morphology of their arms & hands can be entirely unaffected. Their wings might perhaps look much like a dragonfly's but more translucent (less transparent). [![enter image description here](https://i.stack.imgur.com/3mZEH.png)](https://i.stack.imgur.com/3mZEH.png) But where on the body will these wings be & which two ribs should we use? As you can see from this picture the horizontal centre of balance of the human body (with swept back arms to make it slightly more aerodynamic) is basically just above the hips. [![enter image description here](https://i.stack.imgur.com/rUzMq.png)](https://i.stack.imgur.com/rUzMq.png) So (contrary to normal depictions of wings sprouting from shoulder blades) the small of the back is it seems the best position (yes, I didn't expect that either) so we use the 11th & 12th rib for our fairy wings. [![enter image description here](https://i.stack.imgur.com/wUXGt.png)](https://i.stack.imgur.com/wUXGt.png) They're not quite far enough down for perfect balance in horizontal flight but that's OK, leaves some wriggle room for a larger head & brain (to help make reasonable intelligence less implausible). The 11th & 12th vertebra probably fuse for strength & evolve into a shape better suited for anchor points for the wing muscles, imagine a ridge or 'keel' rising from the back of the fused vertebrae & then extending into a plate that looks something like four symmetrical scapula fused together with the socket joints facing out (two on each side) resting on top of the ridge rising up (as the fairy lies on its chest) from the fused vertebrae. So if you cut the wings off you'll be left with what looks like four small stumpy shoulders (with their arms amputated just before the bicep) in the small of it's back. > > Which (sort of) approximates [this](https://www.youtube.com/watch?v=oxrLYv0QXa4) (at 0:45 on the tape) on a dragonfly. > > > The ribs have shortened considerably of course & developed a ball to sit in the socket joint formed on the remolded vertebra & each need six muscles for a full range of motion (rotate one way, rotate the other, sweep forward sweep back, flap down, flap up). There's only three intercostal muscles per rib but I'm confident there are plenty other small muscles that can be expanded & repurposed, the arrector pili muscles of hair follicles for a start (the ones a porcupine uses to rattle its quills) so I don't foresee a problem there. Or we can fuse the 11th & 12th ribs for the first pair of wings & the 9th & 10th for the second pair if we have to (letting us repurpose six intercostal muscles per wing). Of course the smaller end of your scale makes it easier for them to fly & there's obviously no reason a humanoid can't be small. Take the pygmy marmoset for example, that's even smaller than you ask for. [![enter image description here](https://i.stack.imgur.com/LfWEx.png)](https://i.stack.imgur.com/LfWEx.png) The square cube law really isn't an issue for body design (morphology) at this size (as evidenced by the pygmy marmoset in comparison to other primates) & won't plausibly have any visible effect on it. However, smaller animals have a greater surface area to volume ratio, so more heat is lost, which is probably the main reason smaller mammals have higher metabolic rates (to replace the lost heat), & higher metabolic rates lead to shorter lifespans & mean they need to eat more frequently. Of course as you get really small you begin to come up against issues of plausible intelligence. . > > *Now some math* > > > The average North American male is 175.5 centimeters tall & 10 inches is 25.4 centimeters. > > > So 6.9094488189 of your 10 inch munchkins are as tall (175.5/25.4). > > > So 329.860423747 of them are the same mass (6.9094488189 cubed). > > > A human brain is around 3 pounds which is 1360.78 grams. > > > *So a 10 inch humans brain is 4.12532059634 grams (1360.78/329.860423747).* > > > & are half the height of a 20 inch one so 8 of them fit in one (2 cubed). > > > *So a 20 inch humans brain is 33.0025647707 grams (4.12532059634\8). > > > . > > [The brain of the domesticated cat weighs 25–30 g](https://en.wikipedia.org/wiki/Cat_intelligence) & is [about 0.9 percent of their body mass](https://www.psychologytoday.com/ca/blog/the-superhuman-mind/201302/how-smart-is-your-cat-1) compared to about 2 percent in an average human and about 1.2 percent in an average dog. > > > Cats often perform as well as a two or three year old in cognitive tests & our 20 inch fairy has a larger brain.. with a higher neuron density per gram. > > [A raven's brain may weigh just over half an ounce, but it accounts for 1.3 percent of the bird's body mass](https://www.nationalgeographic.com/magazine/2018/02/bird-brains-crows-cockatoos-songbirds-corvids/), half an ounce is 14.1748 grams. > > > . . > > [Ounce for ounce birds have significantly more neurons in their brains than mammals or primates](https://www.sciencedaily.com/releases/2016/06/160613153411.htm) > > > . > > [Birds pack more cells into their brains than mammals](https://www.theguardian.com/science/neurophilosophy/2016/jun/15/birds-pack-more-cells-into-their-brains-than-mammals) > > > . > > While [Crows can perform as well as 7- to 10-year-olds](https://www.sciencedaily.com/releases/2014/07/140723180824.htm) in some cognitive tests. > > > So (with a large amount of hand waving) we might plausibly & conservatively assign a 20 inch tall fairy with an equivalent intelligence to a four or five year old human, the 4 gram brain of the 10 inch version isn't something I'd want to hazard a guess about. . So what does it "look like" It can look just like a normal human, but smaller, with insect wings, you probably won't even notice the missing ribs unless you examine it very closely. > > *Work still in progress* Dang! forgot about this, I really should tidy it up & finish it off, no time now, tomorrow or later, just intelligence left to comment on I think. > > > [Answer] Let's assume a size of 18 inches and compare to a 6-foot human. This is one-quarter the size, meaning one-64th the weight, all else being equal, for a mass of 2.5 to 3 lbs, or roughly twice the weight of a raven. It is also very similar to the weight of a flying fox, so we can assume similar wing sizes. The brains of such a human bat would of course be a lot smaller than that of a full-grown human, but brain size is not the only factor in intelligence (the amount of convolutions seem to play a greater factor). Their heads could also be relatively oversized, compared to humans. I included a raven in the weight comparison above because ravens are very smart, capable of [astonishing cognitive feats](https://gizmodo.com/more-evidence-that-ravens-are-ridiculously-intelligent-1796882085). Still, we should perhaps not expect full human intelligence in such a small winged humanoid, especially since survival of the species might depend more on other factors. If they retain speech, it will be more high-pitched than for normal humans. Bats have retained a thumb that can be used to grasp stuff, and it is likely that 'fairies' would be similar, possibly even retaining one more finger for better gripping. Their feet are likely to evolve to resemble clawed hands, and a fairy could likely stand on one foot while manipulating objects with the other and the wing fingers. Their lungs would have to be far larger, relatively, to allow for the greater energy expenditure of flight. In turn, their bellies are likely smaller, since flying with a large, full belly is difficult, and hence they would need to eat more times a day, basically snacking all the time. So we should expect large chests (with flat chests for females) and narrow waist. Legs may be folded underneath the body in flight, as for birds, or may have wing skin between thighs for greater lift. [Answer] If they evolved from humans, they would look more like harpies, than fairy: 1. Would they have bat wings? Or feathered wings? - Batwings. Feathers is dinosauros's feature. 2. Could they keep their thumb, index and middle fingers short,... - they could. 3. How does the square cube law affect their anatomy? - they need larger chest for larger lungs (lungs would be about half of there body volume), there bones and legs would be very thin, they would be very skiny - both for flight and due to relative increase in musle strenght 4. Do they have a very high metabolism and need to eat very often like shrews? - Yes. Actually eating and pooping would take most of their daytime. They may have some mechanism that slows down metabolism when they are not flying. But that would mean thay need time to "warmup" before flying and "cooldown" after: drink some shugar sirop, get hot, fly, exaust energy (about half an hour at most), land, cool down (peeing and pooping in process). 5. What about their intelligence? - they will not be fully intelligent. If they are about 0.5-0.7m (20-inch) they can have speech and communicate with normal humans, but they would be smart as small children (not childish behaviour! But, say, inability to get concept of a number, bad short memmory, etc). For smaller sizes, they would be like dogs or cats. ]
[Question] [ Supposing climate change continues at its current "worst case" projected rates, would we see a noticeable reduction in insects down the line? I am wondering if it makes sense to have a character who has noticed a change like this in their lifetime, or if such a change would be unlikely or not drastic enough to attract the average person's attention. [Answer] Yes and No. Even today it is easily possible for older people to notice the change. When you for example compare the amount of insects on your car window from 40 years ago to today it is easily noticeable that the insects have decreased. So why no? Because this decrease is not caused by climate change (at least for the most part), but due to air pollution, with for insects toxic gases. These do not need to be green house gases. [Answer] [![enter image description here](https://i.stack.imgur.com/x1xqX.png)](https://i.stack.imgur.com/x1xqX.png) Scenarios, which are according to IPCC are based on ultra pessimistic assumptions but technically within bounds of science, would give you global temperature higher by 5 C at the end of century. So within remembered lifetime you may get maybe 3 C. While sudden temperature shift would cause (speed up) some extinction, insect have short life cycles and are ultra adaptable. Migration of insects from warmer climate zones is also likely. Maybe, if your character is really good, he can see how species changed. Actually, I think that a scientifically accurate post apocalyptic settings in which temperature is a few Celsius higher and sea level raise haven't reached one meter has a great potential. Those scenarios assume high (but dirty) economic growth. So you may end up with main character who is quite affluent person by contemporary standards and who complains about electricity bill caused by combination of heat wave and excessive use of air conditioning. [Answer] It would depend on how drastic the damage done by climate change was. Also, are you only including climate change in this anthropogenic destruction? Sea acidification and anthropogenic species extinction are both affected by and would affect insect biodiversity too. how far into the destruction are we talking? How far in the future, and how much more damage? I think for a noticeable drop off in insect species there would need to be atmospheric level changes that would also change vegetation, and that would probably throw a few more bones into your future system. So, plausible? Maybe. But it would also probably be an extremely uninhabitable future. Think no insects means no naturally grown/pollinated crops, too, unless you have some system of artificial pollination going on. I would also the question the term "post climate" since any climate is a climate. A true no-climate world would probably be more like the moon since there would be no measurable indicators. But that's just semantics. Cool question. [Answer] Insect population as a whole won't be reduced by climate change. What will, and does, change are the species which you encounter. We have already problems with asian hornets coming to central europe, and there's the fear that mosquitoes (and with them malaria) will spread, as they will be more and more able to survive the milder winters. In turn, local species have trouble adapting and fighting the "invaders", so they are reduced; but the total number of insects will probably even increase (disregarding other pollution effects). ]
[Question] [ Magic has recently become possible in my story, and singing is the mechanism by which humans use magic. A totalitarian regime wants citizens who can speak, but not sing in any way, even poorly. (That is, they cannot produce a note at all.) If necessary, the speaking they are capable of can be whispering, or can be otherwise distorted, as long as it is intelligible. Is there a surgical procedure or some other mechanism that can accomplish this? Can the procedure be reversed? [Answer] > > A totalitarian regime wants citizens who can speak, but not sing. > > > If you're willing to accept sign language as "speaking" you've two reasonably simple options. 1. Cut their [vocal cords](https://en.wikipedia.org/wiki/Vocal_cords) 2. Cut out their tongues If you're not willing to accept sign language as speech for the purpose of your question then your only option would appear to be [tone deafness](https://en.wikipedia.org/wiki/Amusia). 3. to be precise acquired amusia caused by brain damage. They'll still be able to *try* to sing of course, you simply can't prevent that without physically removing the sound making organs but they won't be able to** "sing" in any meaningful sense of the word. Unless you assume a slightly more advanced knowledge of the brain areas involved than currently exists that's going to require a certain amount of research & experimentation to identify the correct bits of brain to cut out or scramble to achieve the specific type of acquired amusia that best suites your requirements but it's certainly doable, though not reversible. It may be possible to achieve that with drugs as well but I've found no links myself to suggest that. *Those are pretty much the only (real world) science based options I can come up with for what you want, none of them seem a perfect match for what you're after but take your pick.* > > Can the procedure be reversed? > > > If you want something reversible (& amusia can't be achieved with drugs) then the vocal chords with sign language for speech are probably your only option, a medical silicon implant stuffed in between the vocal cords so they don't work that could then simply be removed perhaps. Actually, that's the airway we're talking about there so simply stuffing it with a silicon plug probably isn't a good idea if you want them to keep breathing, some sort of collar or ring inserted to prevent them constricting for speech & sound modulation is probably best then. *On balance, some sort of vocal cord insert that can later be removed with sign language for speech is probably the most plausible procedure that achieves the closest to what you want.* [Answer] Use an Electrolarynx The real world has artificial voiceboxes for people who have damaged voiceboxes. They basically detect the motion of muscles in the throat and convert it into sound. Normal speech has many components not related to the throat - mouth shape, volume, etc, and thus the electrolarynx has traditionally sounded "robotic". So surgically damage the voicebox of all citizens, and issue them a tool like the electrolarynx. If desired, make the issued voicebox particularly low quality to prevent tinkerers from hacking it to add additional capabilities, and make researching related technologies tightly regulated. Now everyone speaks tonelessly, and is incapable of singing. Everyone, that is, except for the elite, who have access to far more sophisticated models and/or corrective surgery. [Answer] To be funny enough, to stop people from signing, you don't go for their vocal chords. You go straight to the main man. The brain. There are two areas in brain that are responsible for talking. Broca and Wernicke. One is responsible for understand meaning of words while second is responsible for translation of those meaning into spoken/written words. A mechanical ability. Now the signing is located in all of the brain. BUT We don't "store" songs the same way we do with words. We store the melody. That's why we usually need to lookup the lyrics to understand them. Or focus really hard on dissecting the words we hear in a song. It's not so easy as deciphering speech. BUT To remember the song (and communicate with one) we need to create it. In your case stooping people from creating music is actually very simple. You teach them different time signatures/tempos and scales than the one that create magic. How it works? Same as your regular education. If you are from western culture check if you can sing/remember/repeat some throat singers. If you are pop connoisseur can you enjoy/repeat/remember some 7/11 jazz in Japanese IN Sen scale? Of course you can, with time, learn and understand them but you need to have access to it. Both knowledge and the new music. As you mentioned totalitarian state you can easily imagine that those are forfeit from it's citizens so they "don't get" the music needed to cast spells. ]
[Question] [ A side shot from my series on a computer-less future; see [here](https://worldbuilding.stackexchange.com/questions/129395/a-clock-for-interplanetary-travel), [here](https://worldbuilding.stackexchange.com/questions/100613/can-you-design-your-own-plants-without-a-computer?noredirect=1&lq=1), and [here](https://worldbuilding.stackexchange.com/questions/101519/how-high-def-can-my-tv-be-without-computers?noredirect=1&lq=1). [Project Rho](http://www.projectrho.com/public_html/rocket/torchships.php) defines a torch-drive as an engine with both high acceleration and high exhaust velocity. A torch-ship is a ship with a torch-drive and a specific power of 1 MW per kilogram or larger. The linked page has discussion of various types of torch-drives and others are available on [Wikipedia](https://en.wikipedia.org/wiki/Spacecraft_propulsion#Table_of_methods). Some torch-drive technologies (there are many more that meet the criteria): * [Nuclear pulse propulsion](https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion) * [Gas core reactor rocket](https://en.wikipedia.org/wiki/Gas_core_reactor_rocket) * [Nuclear Saltwater Rocket](https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket) * [Fission fragment rocket](https://en.wikipedia.org/wiki/Fission-fragment_rocket) * [Fusion rocket](https://en.wikipedia.org/wiki/Fusion_rocket) Which torch-drive technology could be implemented in the near-future with the least complex (here defined as cost of design and production) control systems? [Answer] *Nuclear Pulse Propulsion and* Nuclear Salt-Water Rockets** Of the other propulsion methods, these two seem to be the least complex. The other methods require control systems that dive into the operation of the reactor itself, in some cases to an almost intimate and impossible level (for the constraints). For a fission-fragment rocket, one would want to monitor the quantity of neutrons being released by the fissionable materials consistently and without much error, else they risk an overreaction of neutron bombardment—a meltdown. These kinds of torches also require some electromagnetic channeling, which itself warrants a subsystem of monitors and controls. Should this fail, you may risk damaging the exhaust nozzle of the rocket and perhaps other things. There are also other constraints of the device's operations one would want to consider monitoring and controlling, such as the temperature of the ionized particles (you're working in the range of potentially tens of thousands of degrees Kelvin, a few thousand, minimum), and the various integrities of the components of the device; if its a rotating reactor, then you have moving parts and specific alignments to worry about. Gas core rockets have the advantage that they can gain much higher temperatures, thus higher specific impulse. With great power comes great responsibility. A control system for this torch would need to monitor the temperatures of the core's nozzle and containment, which are the structural crutches of the design (for their temperature limitations). One would want to monitor the structural integrity of the containment and control a [neutron moderator](https://en.wikipedia.org/wiki/Neutron_moderator) to increase or decrease the frequency of reactions. This design also requires an effective cooling mechanism, either through external radiators or gaseous/liquid coolant passing through the nozzle. For the sake of maintaining structural integrity or maximizing/minimizing specific-impulse, one would want to control the rate at which this mechanism dissipates heat. In addition to that, it is thought that there needs to be an internal absorption of thermal radiation as well, to control the rate of reactions. Tungsten particles would seem to be the popular choice, and the rate at which these particles are pushed through the reactor would need to be controlled for similar reasons as the cooling mechanism, to delay the degeneration of the device's components. A fusion rocket has the benefit that it cannot meltdown. Much of the concept of a fusion torch is theoretical. There seems to be two predominant types: inertial and magnetic containment. * For the first, one would need to inject pellets of fuel into the reactor and ignite them with high-energy beams of photons or electrons, take your pick. You would need a reliable method for injecting the pellet fuel and a reliable method for activating the beams at precisely the right time and at the right intensity. Typically, you'd do these things inside of a vacuum chamber, so the state of vacuum would need to be controlled. For a successful fusion reaction, one would need to control many beam-to-beam energy ratios on very short timescales (perhaps microseconds). This would seem impossible for an analog system to handle. * For the second, you would require a myriad of control mechanisms and monitors for maintaining a magnetic containment field within small error margins. What you are essentially doing is balancing two powerful forces: a magnetic pressure and a plasma pressure. A fusion reactor is constantly working to overcome turbulence created by high-velocity, flowing ions as they are carried and conducted by magnetic field lines. You have to concern yourself about quantities of the fuel escaping the magnetic containment and interacting with the reaction chamber's walls. All in real-time, and without electronic computers. As for the control surfaces required, in the operation of a fusion reactor, you would need to be a helicopter parent to it, controlling, monitoring, and real-time analyzing just about every aspect of its operation. Nuclear salt-water rockets look promising. The amount of fuel you feed one of these and the degree of temperature it gets to are almost of no concern. One manner of control would be the fuel-feeding system. The particles constituting the nuclear fuel are said not to diffuse all at the same, or even at a regular, velocity. They occupy a broad range of many orders of magnitude, and so it is possible that free-moving particles of the fuel may backtrack into the fuel-feeding system, potentially damaging or destroying the system. Of course, you'd want to have control of the fuel injection rate anyway, to adjust acceleration and whatnot, but this is another reason to have that control. If a detector detects a large enough quantity of the fuel being accelerated back into the system by its own diffusion rate, then you may want to close the system for a short time and let the disturbance pass. This seems to be the only control surface for this device. Nuclear pulse propulsion has been experimented with in the past (see [Project Orion](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion))) and is fairly well-understood. What you are essentially doing is dropping small (or large, if you're looking for a good time) nuclear explosives behind your ship and detonating them at a distance where it is both "safe" and the explosion will impart a good fraction of its momentum onto your craft. You'd need a control to drop the bombs and a control to detonate the bombs. The intermittent stuff is up to your analog computers to figure out. Dropping should be simple. While your craft is experiencing imparted momentum from the previous blast, release another bomb so that your vessel accelerates away from it. My personal recommendation is that you don't put the actual timer (detonation control) on the bomb itself. Let the bomb be activated by some external force, like a focused laser beam vaporizing some part of its surface, a "fuse," or a hypervelocity projectile smacking into it, fired from the ship, a gun perhaps. Why? Safety reasons, of course. Not because it'd be cool to shoot at nuclear bombs all day. [Answer] The Orion Nuclear Pulse Drive is the closest candidate. With the exception of the timing mechanism to fire the nuclear pulse units, you could actually have everything else done by straight mechanical drive. The mechanism to load the pulse units was based on a vending machine, and the cannon to fire the pulse units behind the ship was essentially a giant air cannon. Mechanical timers can run most of the devices, and timing of the shots could be moderated by a cam system in the shock absorbers to trigger the timing cycle. It is perhaps the ultimate dieselpunk sort of technology imaginable, and if the General Atomic crew had been given their funding, they could have gone to Mars by the end of the 1960's, and Saturn by 1975 according to their timetble [Answer] Least complex: all by hand. [![steelworks](https://i.stack.imgur.com/ju6BZ.jpg)](https://i.stack.imgur.com/ju6BZ.jpg) [source](https://www.conservapedia.com/Steel_industry) If you want retro, go full retro. Chains, pulleys and main strength. Your model will be a mid 1800s iron foundry. Instead of that (alarming-looking) crucible you have a self-sustaining fusion reaction lifted from H.G. Wells [The World Set Free](http://www.gutenberg.org/files/1059/1059-h/1059-h.htm#link2HCH0002)Your crew points their various rockets in the direction called for by the captain, quenching or firing up the reactions as warranted. It will take several straining shirtless men to turn off one of the rocket tubes - which is how you get the thing to turn. [Answer] I don't think it gets much simpler than the nuclear saltwater rocket; you should, depending on design specifics, be able to steer and control a nuclear saltwater rocket using mechanical valves, gimbals, and gyros. This is because nuclear saltwater rockets use the same design, in principle, as liquid fueled chemical rockets just with more delta-v and higher fuel energy density. All you need to control is the rate of fuel flow to the reaction chamber and the direction of the exhaust from that reaction. Plotting orbital maneuvers is a different kettle of fish and will require a lot more computational power unless it's being done "by guess and by God" using marque one eyeball, maybe a sextant, and hands on manual steering, which it could be. Even a fully digital system needn't be much more complex than that used by the [Saturn Vs](https://en.wikipedia.org/wiki/Saturn_V) and your smartphone has orders of magnitude more computing prowess. ]
[Question] [ The [talaria](https://en.wikipedia.org/wiki/Talaria) is the name of the winged sandals or shoes famously worn by Hermes in Greek Mythology. If someone were to make a high tech gadget which the attached beating wings to a pair of boots, how exactly would they need to design it to make it fly properly if it could fly at all? [Answer] Note: I'm no aerodynamics expert, so the following may be fatally wrong (I believe each fact is correct, just not sure how they interact with each other...) # Looks like all the ingredients are already available in real life: Take a look at the following real life, working contraptions: 1. This TED Talk shows how a [quad-rotor drone can balance a poll](https://www.ted.com/talks/raffaello_d_andrea_the_astounding_athletic_power_of_quadcopters/transcript#t-130423) on top of it. [![Quad-rotor drone balances a poll](https://i.stack.imgur.com/Ql1zY.png)](https://i.stack.imgur.com/Ql1zY.png) 2. And this TED Talk shows how someone have already built a [working jet suite](https://www.ted.com/talks/richard_browning_how_i_built_a_jet_suit/transcript#t-165296) capable of lifting a human - one of the prototypes involved leg jets in addition to arm jets (Ironman style) [![jet suite](https://i.stack.imgur.com/OPmLL.png)](https://i.stack.imgur.com/OPmLL.png) 3. Finally, this article about [heavy lifting drones](http://www.dronesglobe.com/guide/heavy-lift-drones/) includes a crop duster capable of carrying 10kg of payload (can't link to relevant point in article - look for the "DJI Agras MG-1" model). [![cropduster drone](https://i.stack.imgur.com/0Lsds.png)](https://i.stack.imgur.com/0Lsds.png) So, let's say you want to lift a 70kgs human using "winged sandals", you'd basically need something like a couple of stacked crop-dusters shoes, each with around 35kgs of lift (so 3-4 drones in each stack - those are some large boots, but possible). Add the software to balance the "pilot" and accept control commands from his leg movements, and maybe use some jet power instead of / in addition to the wings - and you've got something that may actually work (I think). Some of the issues you'll need to deal with is power supply, and how close you want these hover-boots to look similar to winged sandals. [Answer] In order to fly with some special shoes you don't need very much, except for an high density "fuel" and the strenght and equilibrium of a good gymnast. [![flyboard](https://i.stack.imgur.com/vVeKX.jpg)](https://i.stack.imgur.com/vVeKX.jpg) As per fuel, high grade fossil fuel is quite mandatory. Jet engines are powerful and small enough to match the requirements. The ironman suit isn't the Stark's masterpiece, the miniaturized arc reactor is. "Endless" amount of energy in a small case: perfect. The main issue is to control the thrust, you have to be trained and in good shape to sustain your body in whatever position in required to manouvre. It's not mandatory to have also arm-thruster or control surfaces as long as you know what you are doing, as someone do with the [flyboard](https://www.youtube.com/watch?v=m4Bm3cs9TFo). They also produce an [airborne version](https://www.youtube.com/watch?v=adK5Enl0aVU), which is more scarying and less funny to see, but it's not limited to a certain height respect to the water. [![flyboard air](https://i.stack.imgur.com/XgSRE.jpg)](https://i.stack.imgur.com/XgSRE.jpg) [Answer] Magic, failing that miniaturised antigrav units with flapping wings for show. The wingspans you'd need to lift a human would be incompatible with actually flapping effectively while on your feet otherwise. [Answer] Lets say you already have really really small wings that flap really really fast. I think your next step is control. Pushing something longish from one and is inherently unstable. Luckily humans are used to being pushed from their feet up (by the ground). However the ground is always pushes in one and the same direction (opposite the center of the the earth to where gravity is pulling). You cant make those magic flip-flops only produce thrust only upwards because you’ll end up with a rather weird elevator rather than a flying machine kind of thing. You want to be able to angle the thrust. This is significantly easier if you can vary the amount of thrust. Perhaps something like system that detects if there is resistance and only produces thrust when you push actively against it. Oh, and one more thing. You may want to make those sandals boots for your more “acrobatic” flights. If youtube has told me anything, its that footwear is the first thing that comes of when something goes spectacularly wrong. Now that i think of it, there are some other items of clothing that one can attach wings to, that perhaps make the task easier. [Answer] Stability would be your biggest problem. The pole in the video above is nice and all but it's not a body. How does your gadget cope if the wearer leans too much and topples? What stops the wearer ending up upside down? It's well saying you have programmed stabilisers which can support you weight, but are they able to stop you moving completely? If they can, what happens if you fall backwards? Your feet can't move so what stops you breaking your ankles or knees? Either you'd need a harness to protect your legs from such a thing or a safety features that allows the device to tip when it senses a fall, or better yet, moves to stop you falling. Then you might be looking at sensors which can be placed on your body so that the device can keep you upright. ]
[Question] [ This question was originally posted in the [Sandbox](https://worldbuilding.meta.stackexchange.com/q/6168/32016). It's set in the same world as [this question](https://worldbuilding.stackexchange.com/questions/80301/solid-material-made-from-human-blood), but is not related to it. --- I have a speedster character whose top speed is Mach 2. She holds back a lot of the time, but at full tilt she can accelerate to that speed - or slow to a stop from that speed - in exactly one second. Some quick Googling and back-of-the-envelope calculations tell me that this equates to an acceleration of 2,250 ft/s2 (686 m/s2), or about 70G, which is far more than an ordinary human can withstand. I've therefore decided that my speedster will be passively immune to any physical effects that she would otherwise experience when accelerating or running at those speeds. These immunities would apply even when she isn't actually running. It's not a magical protection like the Speed Force, but a set of latent physical attributes. I already know that she's going to be immune to G-forces of up to about 75G (735.5 m/s2) - anything below that will feel like 1G to her. She also has superhuman reflexes, to avoid faceplanting into the nearest wall as soon as she starts running. My question is: What other physical attributes does she need to have in order to be able to survive such intense speed/acceleration? Is there anything else I've overlooked that she needs to be resistant/immune to, and is her existing G-force tolerance sufficient? Answers should ideally mention the implications of these increased tolerances. Other notes: * She wears goggles to protect her eyes while running, so that's not a concern. * She's not immune to psychological effects, so a sudden deceleration might not hurt her but it would still disorient her. [Answer] The additional pressure she'd receive at that speed would be immense, and the pressure *differential* between leading surface and trailing surfaces would be twice immense, and the insanely strong low pressure zones which will occur wherever there are vortices generated (any surface discontinuities, wrinkles in clothes, tips of ears, point of jaw, elbows, knees, let alone the stresses on hair - sheesh) will be highly variable, moving across her surfaces, and sometimes truly exponential. So somehow she needs to be *utterly unaffected by immense pressure, both* positive and negative. Moreover, as pointed out above, she will pass through the Mach barrier as she accelerates to her top speed, and this will cause not only massive pressure on her leading surfaces, but also shockwaves which would leave vapour bursts and acoustic shockwaves in her wake, stunning anyone close by - effectively being an intrinsic weapon. If you read up on the technical challenges we had breaking the Mach barrier, and the huge resonances, vibration, and shockwaves generated, which literally tore airframes apart, stripped aerodynamic plating right off the airframes, and in many cases killed pilots outright, I think she'd need to be almost as invulnerable as Superman to simply survive one single acceleration / deceleration sequence. Good news is, if she, and all her cells, living and dead, are invulnerable, she won't instantly go bald... She will need a high energy density energy source other than just food, as her metabolic burn rate would be far higher than even a hummingbird or shrew, necessitating her eating many time her own bodyweight in food to keep out of energy debt and simply dying. The old Superman comics pseudo-science dodge was that he was made of far denser matter than humans, and that our yellow sun somehow gave him energy - of course, with the level of invulerability he routinely demonstrated, he'd have had to be so dense that he'd have weighed tens of tonnes, and yet somehow we never see Superman leaving crushing footprints in steel or rock, or wading through soil... [Answer] She'll need some kind of adaptation in her inner ear to avoid getting insanely dizzy with her first step. Depending on her top speed, accelerating at 690m/s^2 will put her above the speed of sound in just under half a second. She will be unable to hear anything behind her, and anything in front of her would be drowned out by the sound of the wind. Further, at these speeds, air compression starts to cause noticeable heating. She may need some kind of adaptation to avoid cooking herself. She'll also need improved durability. If she tries to punch anyone or touch pretty much anything while going that fast, it's going to hurt. Normal people standing still occasionally break their own fingers when throwing punches. Imagine how badly mangled your hand would be if you threw a punch at Mach 1. [Answer] As others have said, increased durability would be helpful here. Especially on her feet. Going at that speed is going to be more than a little rough on her shoes (if she wears any, hopefully she does.) The impacts with the ground and the friction are also likely to kill her feet if she doesn't have some sort of ability or technology keeping her feet safe. (I'm not sure if this falls under your "passively immune to any physical effects" thing.) I'm with Ryan\_L when he says that everywhere else needs durability too. If something small that you can't avoid with super reflexes (like, I don't know, a piece of gravel?) hits you going at Mach 2, it might kill you. Or if it doesn't, it's gonna give you a bruise and put you in a lot of pain, which you might know if you've been hit by a piece of gravel going only about 30 mph. So yeah, invulnerability is good. (The goggles will also need to be reinforced with something that's strong on a massive scale, or else they're not going to last too long, either.) I might add that invulnerability should only be active when she's using her superspeed, or else she won't be just a speedster anymore. She'd be, well, invulnerable, and that might defeat the purpose to some degree. She'll also need to have some sort of way to breathe. At high speeds, it might be hard to breathe because of the pressure difference of the air in the lungs and the outside air. (I'm not good at fluid physics, so research this to make sure it's correct, though I'm nearly definite it is, based on theory and personal experience.) I'm not sure how you'll adapt to this- I'd suggest some sort of technology in the form of an artificial oxygenator, though this might be inconvenient when she's not using superspeed. Other minor things: does she make really fast steps, or are her steps just really long? If her steps are really long, increased reaction time might not be enough, because you can't really control how you're moving if you're in the air. It'd be weird for her to have to shorten her strides if she needs to turn or something, so I'd therefore suggest she makes fast steps. How does she stop? I feel like that's going to do quite a bit of environmental damage unless she stops gradually. If she decelerates at the rate of a normal car, say, she's going to go really far before she stops. If she decelerates such that she takes the same amount of time to stop, that's going to do work on whatever surface she's standing on, I'd think. [Answer] When she accelerates like that she will compress air very fast. This will cause flames without a combustion, just like what meteors and satellite debris do on atmospheric entry. She'll have to be immune to that heat. Notice that the air will also be compressed inside her lungs, whether she holds her breath or not. This will inject a poisonous amount of oxygen in her system. She might survive that much acceleration, but her intestinal flora will not. If she runs often, she will have a constant case of the runs (pun intended). [Answer] She'll need far greater gee tolerance to survive in the event that she does hit a wall, such as if she's distracted or deflected, or someone trips her. Perfect reflexes only count for so much if you're up against others with super powers; as it stands the deceleration of a forced stop will still be lethal to her and many another standing too close to ground zero. ]
[Question] [ Starting at the most basic of theoretical questions, is it chemically possible for these minerals to be deposited by an organic enzyme? I'm particularly interested in diamond because it's pure carbon, which is very plentiful in the environment. Perhaps, for example, one enzyme might set down methane molecules together to form a sort of seed crystal, then another enzyme might continue the process by stripping of a hydrogen atom and depositing methyl group in its place until the crystal grows to the right size. In short, is the energy required to form these diamond bonds too high for an organic enzyme to make? Then, assuming that's possible, would a skeleton that uses diamonds have any significant advantage in terms of strength over the normal hydroxylapatite bones (assume the crystals are roughly the same size). Lastly, if diamond is a particularly poor choice for this application for whatever reason, would other gem grade minerals (e.g. quartz, corundum, beryl, etc.) function better? In terms of the rest of this particular creature's anatomy, it's basically a human that's been augmented by magic. The magic has made all of its body systems as efficient as possible, in effect replacing the "good enough to breed" standard of evolution with "as close to perfect as humanly possible". However, I want to avoid using magic to make its body function on a day-to-day basis. [Answer] There is a fundamental reason why bones are not made by crystals. Everyone seems to think that diamond is the strongest material, but have you ever wonder how does it come into the shapes you see decorating the fingers or the cleavages of those fine upper class, cocktail sipping, ladies? Diamonds do not come out of the earth already fitting a ring, they need to be worked to the proper shape. And how do you cut the hardest known material? Are NASA, FBI, Monsanto and the free masons hiding from us the "stronger than the strongest" material? No, crystals are very weak when a force is exerted in very specific direction, and they easily get cleaved. When I started cleaving silicon wafers at the university, I was amazed that I could split a pizza size wafer in two just by a swift touch on the edge, while to split a pizza in two I had to use much more effort. Now, when you are using your bones you don't want to worry that the forces you are applying to them are not oriented along those cleaving directions. That's why isotropic materials are preferred by Darwinian selection. Also consider that when you put together two crystals with different orientations the boundary is a weak point. That's why putting together several micro-crystals would not be better than a crystal or than an amorphous and isotropic material like apatite. P.S. Don't forward this answer to the final boss of any game where you wear diamond armor. [Answer] Bones are so good because they are strong but also a little bit elastic. Gems don't have this. For example see the The Brittle Bone Experiment (referenced below): in this experiment they remove all the organic material in a bone. What's left is only hard minerals. Should be really strong right? No, it would break the moment you fall from a high place. Why doesn't it break? Since it can bend a little bit. [detailed explanation](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5061452/) [easy one](https://askabiologist.asu.edu/bone-experiments) [Answer] Bone is a composite, and has about 4-5 times stronger than steel by weight, switching to any regular crystal will just make it brittle. diamond and quartz are hard not strong, (quartz is basically glass) you could snap a rod the thickness of your finger bones between your fingers. Bone is non-crystalline which is important, crystals are weak. There are actual diseases that cause bones to form crystalline structure and they make them very brittle in the process. Could you make bones from something stronger, yes bone is rather poor as far as material strength, but the strength to weight ratio would end up being vastly inferior because your body still needs the calcium and phosphate so most of the bone weight will still be there. weight is a big issue, as it drastically effects the forces and calories needed to move. Flexibility And elasticity is also an issue bone has really low Young's modulus so under excessive loads bend instead of breaks. there are very few material that can match both strength and Young's modulus of bone at the same time, including man made composites. Poor Wolverines joints are getting pounded into mush with every step, if he did not have a healing factor he'd be crippled within weeks because he has no shock absorption. All of this could be overcome, but there is one final nail in coffin. Calcium and phosphate are water soluble and thus fairly easy to move around, so bone can be repaired constantly, and it has to be. The stresses we put on bone would result in constant micro-fractures no matter what you made it out of. Quartz especially would be very difficult to repair as silica has very low solubility. [Answer] Possible yes, but a good idea probably not. Bones are calcium, this is a mineral, it's a metal actually. If organic biology can lay down one mineral then there's no reason to suppose evolution couldn't develop organisms that lay down other minerals. Aside from the utility & usefulness of those other minerals to an organism as dictated by mother nature through evolution & natural selection of course. There are in fact examples of other minerals laid down by organisms in the real world, some [snails that live around deep sea vents](https://en.wikipedia.org/wiki/Scaly-foot_gastropod) do actually grow their shells out of another metal. The only real question is would this other mineral provide an evolutionary edge to the organism that uses it for it's bones, most crystal probably isn't a good choice, at least not for bones, your diamond bones may be hard but will also be brittle, so lateral blows to long bones are pretty likely to cause it to shatter far more easily than our calcium bones, possibly not a good idea then. [Answer] I would suggest some more exotic materials to strengthen bones. Carbon nanotubes run through a ceramic substrate might be stronger than calcium. And the nanotubes have interesting electrical properties that could be used in the replacement for nerves also. Diamond is hard, but also fragile. But I agree with using carbon, it has so many useful forms. In addition to replacing the material the bones are made out of, I'd also think of the optimum shape for the nerves. The obvious shape is not always the best shape. For example, our spinal vertebrae are prone to being damaged by bending. Perhaps a differently designed spine would be better. The same with the long-bones. Think of a solid square beam of steel. You can make this stronger and lighter by using an I-Beam of the same dimensions. They make more complex beams now that have more strength in more dimensions than the i-beam, but use more material and weigh more than the simple i-beam. ]
[Question] [ Okay, now this question is a bit random. But, I'm planning for a possible book project about a 2019 expedition to an undiscovered island. The island is near the northern tip of the [Ninetyeast Ridge](https://en.wikipedia.org/wiki/Ninety_East_Ridge) in the Indian Ocean. I think the book will be in a similar format to James Gurney's Dinotopia, existing as both a story and a "scientific journal" of the protagonist. The only thing is, the fauna on this island includes descendants of tigers and various south Asian small cats, rhinoceroses and other fauna typical of Indonesia, Malaysia and nearby regions. However, other animals on the island hail from African ancestors - notably the last surviving members of the [Protelinae](https://en.wikipedia.org/wiki/Chasmaporthetes) or "dog-like hyena" subfamily\* (Excluding the aardwolf\\.), as well as other bone-crushing hyena species. The last biogeographical obstacle is the presence of earless seals on the island. The only seal that favours tropical climates are the monk seals - With one extinct species\\\* in the Caribbean, one in Hawaii, and one in the Mediterranean. To me, the Hawaiian monk seal looks like the best candidate for a migrator, but there's still a massive distance between Hawaii and Ninety East. However, anyone who's heard of a [Baikal seal](https://en.wikipedia.org/wiki/Baikal_seal) will know that seals are very good at overcoming geographical obstacles. So, this sounds like a lot of zoology, and a lot of paleontology too. But really, I don't need a zoology or a paleontology expert to answer. The main thing I need in a respondant is someone who is versed in geography and knows how an island the size of Ireland\\\\ (The country, not the whole island) could end up on the Ninety East Ridge with East African fauna dating from 800,000 BC as well as more recent South Asian animals. My basic theory is that the island could have split off from East Africa, and the Asian wildlife could have colonised it somehow, but I'm no geographer. I doubt that it would be possible for it to join up with Sundaland (I believe it was a thing fairly recently, again, not a geographer.) Also, if anybody knows how earless seals could get from Hawaii, past Indonesia and to my island, then I'd love to hear from you. Note: I know that this question may raise the hackles of some people who don't like science/what-if questions, but really this is the only SE site that relates to this. It's a mixture of geography and biology and involves heavy speculation. So, if it's voted to be closed, then there's nothing I can do about that, but please understand that this is the best site, as far as I know, to ask this question. \The large members of this subfamily didn't go extinct like their mainland counterparts due to the absence of large canids on the island - when dholes and other small canids arrived at the island, the Protelinaeans were dominant and could not be out-competed. \\* If the whole 800,000 BC thing doesn't fit into a plausible timescale, I could potentially have more recent aardwolves evolve into large running hyenas. \\\* Just because it's extinct now doesn't mean it could have colonised the island before it went extinct, but as said, I think that the Hawaiian seals are a more plausible option anyway. \\\\ I can change the size if it's necessary. [Answer] It seems impossible to find an island that have split off from Africa and moved that far in the east of Indian Ocean. You're far beyond the limits of [somali plate](https://en.wikipedia.org/wiki/Somali_Plate). So it would be more plausible to explain the presence of african species by an ancient migration. Your island seems to be very close to Andaman islands. Indigenous people from Adaman, like the [Jarawas](https://en.wikipedia.org/wiki/Jarawas_(Andaman_Islands)), look more like African than Asian people. [![Jarawa kids](https://i.stack.imgur.com/Ch5wy.jpg)](https://i.stack.imgur.com/Ch5wy.jpg) The Adamans appears to be a milestone in the [great coastal migration](https://en.wikipedia.org/wiki/Southern_Dispersal) of Humans along the shores of Indian Ocean. Black tribes came from Africa via the Arabian peninsula, and then they migrate toward India, South-East Asia and Oceania. [![enter image description here](https://i.stack.imgur.com/TxfAG.jpg)](https://i.stack.imgur.com/TxfAG.jpg) So we can imagine that other african species may have followed the same road, and reached your island when the sea was lower, during the ice age. Even if your island was never directly linked to the continent, it may have been close enough to allow terrestrial animals to end up there. After the sea rises they would have been definitively trapped on the island, but they found a way to survive. [Answer] Biogeographically, you shouldn't have a problem. It can be an island with really odd fauna due to rafting events. Just make sure your African animals had a Eurasian distribution at least once. Your island is pretty far for them to survive the voyage. <https://en.wikipedia.org/wiki/Oceanic_dispersal> As a geographer, you might want to consider how to explain the geological origin of your island. If you want to go with a chunk of Gondwana breaking off, then I'd suggest this site <http://www.hhmi.org/biointeractive/earthviewer> to get a better understanding of how India, Africa, Australia, and Antarctica fit together and subsequently broke apart. It's not unheard of for remnants of Gondwana to become "sunken continents" (hello, New Zealand and Kerguelen) but right now all the former parts of Gondwana are accounted for. So you might want to think about what part of Gondwana you want to cut your island out of. [Answer] Based on the location of the island, I'd say it is somewhat plausible. Maybe the way the island formed is that the tectonic plates did something different in an alternate timeline. Some animals may have migrated there, that is possible. Species that are extinct elsewhere can survive there as it has happened in reality. But there are some animals, like the tigers and rhinoceros, I don't agree could be there naturally. But maybe the island was connected to Africa and other places before lots of it sank somehow, like a lost continent. Or an ancient, now lost, civilization brought them there for hunting or living there purposes. It's really up to you. I hope I answered your question well! [Answer] Not really The thing is your fictional island is it is located at the tip of a mid-oceanic ridge as an oceanic island out in the middle of the ocean. There is a parallel in the form of [Christmas Island](https://en.wikipedia.org/wiki/Christmas_Island), which is located near where you have your landmass but is much, much closer to the Indonesian mainland. And Christmas Island's native mammal fauna consists of...[two bats, two rats, and a shrew](https://en.wikipedia.org/wiki/List_of_mammals_of_Christmas_Island). This is about what you'd expect for your fictional island assuming similar processes. Probably more if the island was the size of Ireland, but the fauna would be almost all rodents, bats, and shrews. Carnivores in particular are terrible at dispersing to islands. The issue being that most of them are large, and thus cannot raft, because they exist at low population densities (and thus are less likely to disperse), and because they are carnivorous and have trouble finding enough food to sustain themselves. [Most cases of carnivores on islands are on continental islands, in which the island was connecting to the mainland during the ice age and subsequently because isolated when sea levels rose](https://www.journals.uchicago.edu/doi/abs/10.1086/382229). In fact, the region why IRL Indonesia has so many large mammals is because it was once one big land mass during the ice age and rhinoceroses and tigers could walk to most places that are now islands. Even many carnivores such as the Channel Island fox (Urocyon littoralis) [are thought to have been originally introduced to the islands by humans thousands of years ago](https://www.sciencedirect.com/science/article/pii/S0033589408001567). Some carnivores have been known to cross oceanic boundaries, but they tend to be very small, omnivorous species like civets and raccoons that can survive the journey on rafts. Or otters. The only species you've listed that could potentially make the journey are tigers, which have been known to swim to islands, but nowhere near that far. The other issue is an Ireland-sized island probably couldn't support the diversity of animals that you wanted. Island ecosystems are very fragile and often can't support a huge diversity of megafauna all together at once because they can only support small populations. Ireland did have a number of large mammals, but this is because it was a continental island and the fact that wolves, bears, Irish elk, and many other large mammals were rapidly wiped out by human arrival shows how fragile these ecosystems can be. Big animals in general also don't raft very well. The only big mammals which are known to disperse across oceans reliably are hippos, elephants, and tigers, and a lot of that is because they swim the distance rather than rafting. Hyenas would be completely out of luck. [Answer] ## This might be what you're looking for... <https://en.wikipedia.org/wiki/Lemuria> Lemuria is a hypothetical landmass, that of course never existed... but it was located between Africa and Asia. The Ninety East Ridge was pretty much its center. That's of course not a geographically correct answer, because we pretty much know that this landmass never existed, but your island is fictional... so a fictional explanation might help. [Answer] Thousands of years ago, Austronesians from Indonesia sailed to Madagascar and settled there. Later on, Bantus from Southeast Africa came to Madagascar and mixed with the locals. The point is that an ancient connection between Indonesia and Africa is possible. Other ancient fauna migrations include the voyage of Old World Monkeys to the New World. So if humans or some other force caused Indonesian animals to sail to Madagascar (or caused African animals to sail to Indonesia), that could work. If you're willing to change geography, this event is much more plausible if there was a vary large island or a chain of islands between East Africa and Indonesia. ]
[Question] [ Let us take an earthlike planet. Approximately same radius, atmosphere and climate. Now let us create an approximately circular, paleovolcanic mountain approximately 30 kilometers in height and 150 kilometers in radius, not dissimilar from Olympus Mons. The crater's radius is 20 kilometers and its depth is 10 kilometers. The mountain is located in a temperate continent similar to Europe, surrounded by grasslands, forests, hillscapes and normal mountain ranges similar to the Alps. It borders the ocean to the south. My question is: How would such a mountain look from orbit and from the surface? What vegetation and climate zones would exist? Is it true that there would be no snow above 15 kilometers due to lack of water? [Answer] This mountain will look... unrealistic. There is a limit to how high a mountain can be in a certain level of gravity [how high can mountains be](https://talkingphysics.wordpress.com/2011/09/08/how-high-can-mountains-be/) For Earth, this limit is less than 10 km. (The basic idea is as follows. Take a column of rock; it will exert a certain hydrostatic pressure on its base, proportional to its height. At a certain point this pressure will reach the maximum which can be supported by the material; any attempt to make the column higher will make the material at the base flow sideways. Granite has a density of about 2.7 grams/cubic centimeter and a compressive strength of about 200 MPa or 2 million grams-force/square centimeter; simple arithmetic gives a maximum height of about 7.5 km. Real mountains are not columns, so they can be a little higher because the core of the mountain is propped laterally by the sides and because the mountain is not all granite.) However, if your planet has Mars-like lower gravity, your mountain can be higher. If, for argument's sake, we allow this mountain to exist, it will look like big round glacier with naked top, probably with some glaciation inside the crater. Atmospheric conditions in stratosphere do not support glaciation (boiling point of water drops to -50-60C). [Answer] To be clear: this is not a question about whether a 30km mountain on an earth like planet could exist. It is a question about how it would look. I found this fine math laden site which shows the maximum height for a mountain made of granite. <https://talkingphysics.wordpress.com/2011/09/08/how-high-can-mountains-be/> > > The density of granite is ρ = 3 g/cm3 (actually, the densities of most > liquids and solids are close to 1. Lead is only about 11 g/cm3 and > gold is 19.3 g/cm3). The total weight of the mountain is just the > volume times density times g so: > Weight W≈ ρgr2h > To see when the rock > will start to break, we’ll compare the stress of the weight of the > mountain to the compressive strength of granite. (Most mountains > aren’t made out of granite, but it should give us a good upper limit > on mountain heights). The weight of the mountain is spread out over > an area of roughly (ignoring constants such as π): A ≈ r2 so the > stress σ the mountain exerts on the ground underneath it is: > σ ≈ W/A ≈ (ρ g r2h)/r2 ≈ ρgh > The compressive strength of a material is the maximum compressive >stress a material can withstand before it starts to deform. > For granite the compressive strength is σC = 200 > megaPascals = 2 × 108 N/m2 so the rock beneath the mountain will start > to compress when: σ = σC or ρghmax = σC. Rearrange this equation to > solve for hmax yields: hmax ≈ σC/(ρg) The max height for a mountain > works out to be: > > > hmax ≈ 2×108 N/m2/(3×103 kg/m3 ˙ 10 m/s2 )≈ 104 m = 10 km > > > So a granite mountain can only be 10 km. A mountain on earth which was 30 km must be made of material that is less dense, or which has a higher compressive strength. Less dense is a nonstarter because granite is not that dense at 3, and less dense materials have markedly less compressive strength. More compressive strength is a tall order because granite is the best among stones at 200. So not stone. [Sapphire](http://www.roditi.com/SingleCrystal/Sapphire/Properties.html). Sapphire is more dense than granite at 3.98 (we will use 4) instead of 3 g/cc. But the compressive strength is 2 GPa - that is 2000 MPa or an order of magnitude greater than granite. Plugging in these new values hmax ≈ 20×108 N/m2/(4×103 kg/m3 ˙ 10 m/s2 )≈ 754 m = maximum of 75 km So 30 km is fine. This mountain would not necessarily be a single crystal of sapphire. But that would work. So here it how it would look. [![crystal mountain](https://i.stack.imgur.com/s2zFQ.jpg)](https://i.stack.imgur.com/s2zFQ.jpg) <https://orig08.deviantart.net/a5c2/f/2014/021/f/a/crystal_mountain_by_elbardo-d734c7a.jpg> Except for those birds. Nothing is flying up there. At all. Also I object to that curly mountain at the side. But the principle stands. --- ADDENDUM I was thinking that maybe it is unrealistic to have a giant sapphire crystal. Where would it come from? A mountain of diamond seems so trite, but really it would be better in many respects. Lets get it over with. So [diamond](https://en.wikipedia.org/wiki/Material_properties_of_diamond): density of 3.5 and compressive strength of 60 GPA; maximum mountain height is 196 km These diamonds would have been [formed in the atmosphere of a ancient gas giant](http://www.bbc.com/news/science-environment-24477667) and then incorporated in the crust of this Earthlike world. I envision this huge, partly fused mountain of diamond extending farther down below the surface than it does above. Despite the huge mass balanced on one point, it does not sink further down because the bottom of the mountain is floating in denser, partly metallic molten materials. The diamond mountain is essentially an iceberg in the crust. This also gives insight into how this diamond iceberg mountain would look. There would be no plants on it and no ice or snow. Diamond is one of the best thermal conductors there is. With its big bottom side down into the mantle, the entire thing would be very hot. [![diamond mountain](https://i.stack.imgur.com/sHgnA.jpg)](https://i.stack.imgur.com/sHgnA.jpg) my own assembly. [mount hood](https://travel.usnews.com/Portland_OR/Things_To_Do/Mount_Hood_52553/) with [uncut diamond](https://www.pinterest.com/pin/18436679698052773/) . [Answer] It depends on where from space really. As @Alexander had said, it is quite unrealistic too. If viewed from the moon it would be visible(if not completely by the naked eye). It is bigger than Switzerland: [![150km Radius](https://i.stack.imgur.com/gIGHh.jpg)](https://i.stack.imgur.com/gIGHh.jpg) Secondly, for your question of "Can it snow above 15km?". I am not sure, correct me if I am wrong, but it can't snow if it is too cold so it wouldn't snow at that altitude. > > Paradoxically, just as the air can be too cold to generate much snow, it can also be too hot to generate much rain. The reason is partly because record-high temperatures generally coincide with high-pressure systems that feature plenty of sunshine and stable air. > > > ]
[Question] [ I plan to write a novel set on old Venus. What I mean by this is that it is set on a Venus where it was still thought to be a swampy planet. I know that is an unlikely past, but I have read oceans may have once existed on Venus but were probably lost to a runaway greenhouse effect. So reality check: is it plausible that Venus was once a swampy planet reasonably habitable to Earth like beings? [Answer] Since this is a science-fiction story set in an alternate reality, yes you can write about a swampy Venus. Firstly, this is an established concept in previous generations of science-fiction, and in the same way steampunk fiction harks back to earlier versions of speculative fiction of the kind written by Verne and Wells, there is no reason why you can't use swamp-infested Venus. A recent anthology of swamp Venus stories titled Old Venus, edited by George RR Martin & Gardner Dozois, was published in 2015. So this can be science-fiction subgenre in its own right. There is no reason that makes sense to restrict writers to writing about a scientifically accurate Hell planet Venus. Science-fiction is a literature of the imagination as much as reason and speculation about possible realities. If you want to add scientific authenticity to your swamp planet Venus either the Sun needs to be cooler, which is plausible because it was a cooler star in the past, or perhaps further from the Sun or a combination of both. This will keep Venus cool so there isn't a runaway greenhouse effect. The drawback is that Earth will be colder. Possibly, permanently glaciated with a cooler Sun. You can cheat by giving Earth more active and productive sources of methane to keep its global temperature up and at a level where our biosphere or a sufficiently close version of it can exist. Normally I'd advise a science-fiction writer ignore being too pedantic about the scientific accuracy and just allow Venus to be a swamp world and leave it at that. Just go for it and write the best swamp Venus story you can. [Answer] The scientific community doesn't know for sure, but it is certainly possible, even plausible, that the planet supported liquid water. What isn't clear is whether this water survived long enough for life to develop into the complexity necessary for a swampy surface. Quoting <https://en.wikipedia.org/wiki/Atmosphere_of_Venus#Evolution> > > Through studies of the present cloud structure and geology of the surface, combined with the fact that the luminosity of the Sun has increased by 25% since around 3.8 billion years ago, it is thought that the atmosphere of Venus up to around 4 billion years ago was more like that of Earth with liquid water on the surface. The runaway greenhouse effect may have been caused by the evaporation of the surface water and the rise of the levels of greenhouse gases that followed. Venus's atmosphere has therefore received a great deal of attention from those studying climate change on Earth. > > > There are no geologic forms on the planet to suggest the presence of water over the past billion years. However, there is no reason to suppose that Venus was an exception to the processes that formed Earth and gave it its water during its early history, possibly from the original rocks that formed the planet or later on from comets. The common view among research scientists is that water would have existed for about 600 million years on the surface before evaporating, though some such as David Grinspoon believe that up to 2 billion years could also be plausible. > > > The early Earth during the Hadean eon is believed by most scientists to have had a Venus-like atmosphere, with roughly 100 bar of CO2 and a surface temperature of 230 °C, and possibly even sulfuric acid clouds, until about 4.0 billion years ago, by which time plate tectonics were in full force and together with the early water oceans, removed the CO2 and sulfur from the atmosphere. Early Venus would thus most likely have had water oceans like the Earth, but any plate tectonics would have ended when Venus lost its oceans[citation needed]. Its surface is estimated to be about 500 million years old, so it would not be expected to show evidence of plate tectonics. > > > [Answer] We can't rule out Venus at one point in time having an Earth like climate some billions of years ago. So we can speculate on the existence of a Venetian Marsh. There are two types of Marshes, Fresh water and salt water, and we can immediately eliminate one of the two types on an attribute Venus lacks. Salt water marshes are formed due to the tide. Venus lacks a moon and as such would not have a defined lunar tide. I suspect we can confidently say if Venus did have salt water oceans, a salt water marsh would likely not exist due to the lack of a moon. So issue number 1 - no moon. That leaves us with fresh water marshes. On Earth, the <https://en.wikipedia.org/wiki/Everglades> Florida Everglades is probably the best example of a Fresh water marsh thats self sustaining. It is extremely dependent on Aquifers, but more over...Limestone formations. These formations allow the aquifers to exist and work to keep the PH relatively neutral. Limestone is primarily calcium carbonate, which is created by ancient sea life over the course of millions of years. Lets say for whatever reason, Venus was capable of supporting this ancient sea life and give birth to limestone. This brings us to issue number 2...Venus lacks plate tectonics. On Earth, the plates shift over time and this limestone formation is relocated to the surface and becomes exposed land. There is no process on Venus that would bring this formation to the surface and it would simply be buried under more and more layers. Without this formation and the aquifers it brings, it's likely this marsh would never come to be. To go a step further...because it's lacking plate tectonics, Venus releases it's interior energy through volcanoes that includes a high sulfur content and would make the waters of a marsh harshly acidic without the limestone to counter that. That being said...Fresh water marshes also come in the Prairie pothole variety <https://en.wikipedia.org/wiki/Prairie_Pothole_Region> It would require Venus to have a glaciation cycle, but may be the only example I can find (they lack drainage and fill yearly with snow melt). Life can contend with higher acidity levels (some life will even sequester the acids)...but the question of whether Venus could have glacial cycles needs to be asked. Not sure if I could find an answer to that one. The other versions of Marshes tend to be seasonal, completely drying during the summer months. Due to the lack of a moon and plate tectonics, I believe the marsh Venus scenario is highly unlikely...however with that being said, I only have examples on Earth to work with. On Venus, a Marsh-like feature that doesn't exist on Earth due to many other factors is still possible. ]
[Question] [ My planet has an increased axial tilt, resulting in crazier winters and summers and higher temperatures. For most places, the temperature never drops below freezing - even in the winter, but the days can be as short as four hours during this time. I want my fauna to reflect this, and rely less on photosynthesis (which will also give me the chance to make everything less green!). However, I also want quite a bit of oxygen in the atmosphere (around 30 percent of it to be this way). I've already looked up fungi and dodder style plants, but they don't appear to create oxygen. My question is, how could I go about creating plants like this in a scientifically plausible manner? [Answer] Plants create oxygen as a byproduct of photosynthesis, using energy from sunlight to break apart molecules of water and carbon dioxide and reform them into carbohydrates (such as glucose) and oxygen. If you want a substantial amount of oxygen in your atmosphere, that oxygen has to come from somewhere- either from oxides in the ground (most likely quartz crystals or metal ores), or from CO2 in the air. And liberating oxygen from any such source requires energy. That energy has to come from somewhere. There are a few exothermic reactions that release oxygen (such as the ["oxygen candles"](https://en.wikipedia.org/wiki/Chemical_oxygen_generator) popular on submarines: $3NaClO\_3 + 2Fe \to 3NaCl + Fe\_2O\_3 + 3O\_2$), but their reactants (sodium chlorate and iron metal, in this case) have to be more reactive than oxygen in order for the reaction to work at all. By the time life starts developing on your planet, any such compounds will have already broken down, and any oxygen released will be bound up in things like quartz, iron oxide, and carbon dioxide. You mention fungi and the parasitic dodder plant, and that they do not produce oxygen. This is true. Fungi are actually more closely related to animals than to plants; they produce energy by breaking down biomass produced by other organisms and reacting it with oxygen to produce water and carbon dioxide. In order to produce oxygen, your "plants" will need to need another source of energy to break down oxygen-containing compounds (most likely carbon dioxide) in order to get at the non-oxygen components, and release the oxygen as a byproduct. All Earth plants power this process with sunlight, because it's abundant and it works. However, some organisms have other energy sources. The [chemosynthetic](https://en.wikipedia.org/wiki/Chemosynthesis) bacteria in [giant tube worm](https://en.wikipedia.org/wiki/Giant_tube_worm) guts, for instance, create carbohydrates by reacting carbon dioxide with hydrogen sulfide: $$12H\_2S + 6CO\_2 \to C\_6H\_{12}O\_6 + 6H\_2O + 12S$$ This produces solid sulfur as a byproduct, rather than oxygen; however, a chemosynthetic organism with a source of hydrogen could react it with carbon dioxide instead: $$6H\_2 + 6CO\_2 \to C\_6H\_{12}O\_6 + 3O\_2$$ Such a hydrogen-eating organism might release oxygen as a byproduct; or, more likely, it could react the oxygen with more hydrogen to produce water and quite a bit more energy. $$12H\_2 + 6CO\_2 \to C\_6H\_{12}O\_6 + 6H\_2O$$ However, I doubt that chemosynthesis will play a major part in your planet's ecosystem. As on Earth, chemosynthetic organisms will be relegated to dark, oxygen-poor areas with sources of reactive chemicals such as hydrothermal vents at the bottom of the oceans. Instead, the foundation of the ecosystem will be based on photosynthesis. You've got a planet with a high axial tilt where, even in the dead of winter in the polar regions that get only a few hours of sunlight per day, the temperatures rarely drop below freezing. There's only two ways for that to be possible: either there's some serious greenhouse effects going on, or the lower latitudes and the summer months get a ridiculous amount of sunlight. If there's a strong greenhouse effect, that means that there's a lot of carbon dioxide, methane, or other greenhouse gases in the atmosphere. Gases such as methane will quickly react with all the oxygen that you have; while the presence of large amounts of CO2 indicates (to me, at least) that your plants aren't doing a very good job of absorbing it and converting it into oxygen. Which leaves sunlight. And lots of it. Photosynthetic plant life will be even more abundant on your planet than it is on Earth. However, you also note that you don't want everything to be green. No problem: there are many different pigments that Earth plants use for photosynthesis, with green chlorophyll only being the most common. See the table [here](https://en.wikipedia.org/wiki/Chlorophyll#Chemical_structure): chlorophyll a is the familiar green stuff, chlorophyll b is yellow, chlorophyll c is blueish-green, chlorophyll d is found in red algae, and chlorophyll f absorbs far infrared light, so it probably appears colorless to our eyes. No one's quite sure why chlorophyll a, which mostly reflects green light, is the most common chlorophyll on modern Earth. After all, the Sun produces more green light than any other color, so it seems like the most common types of plants would be adept at absorbing green light. [![Spectrogram of sunlight](https://i.stack.imgur.com/ytxa9.png)](https://i.stack.imgur.com/ytxa9.png) [(source)](http://sciencequestionswithsurprisinganswers.org/images/sunlight_wavelength.png) Perhaps the first photosynthetic bacteria to evolve on Earth were good at absorbing green light, and blanketed the surface of the oceans. Other bacteria evolved chlorophyll a to take advantage of the red and blue light the surface microbes left behind; and then the purple surface bacteria all died out... for some reason. Maybe. Or maybe chlorophyll a just popped out of a random mutation, worked well enough, and evolution ran with it. There's no way to know. If you want polychromatic flora, just go for it. There's no reason why plants that evolve on another planet need to look just like the ones here. [Answer] You need a source of energy for the life-form to live. Other than sunlight, [we have chemical energy in real life](https://en.wikipedia.org/wiki/Chemosynthesis). It produces oxygen as a waste product when it harvests carbon from the air as a source of material, so you can decouple that from photosynthesis. Look up [autotroph](https://en.wikipedia.org/wiki/Autotroph). No reason why this life-form would be green, though. Poke around in existing questions here on WB! I recall discussing “flex fuel” life-forms※ that could readily shift between available energy sources, which is what you want here: use photosynthesis when possible, but use chemosynthesis in various forms if that’s the only energy available. --- ※ Here's [one place I touched on it](https://worldbuilding.stackexchange.com/a/79747/885). But I think the idea of adapting organelles has been written up in more detail, too. [Answer] You can make a chemosynthesic plant. Imagine something like bacteria, it makes atp but not nadh from an respiratory electron transfer chain that is powered by something like reacting rocks to sulfuric acid(sulphate reducing process), and, now because the synthetic machinery may have been made in a photosynthetic organism, the bacteria can not reduce carbon dioxide without making oxygen in the process(reverse electron transfer chain) and the bacteria have no machinery to consume oxygen. Now you get an organism that uses a fuel cell powered by suboptimal reactions(sulfur oxidization by iron, oxidization of h2s by manganese, metallorespiration, oxidization of iron by nitrates or sulfates, etc.) to drive a high level energy consuming reaction(like the photosynthetic electron transfer chain) that makes the actual material that organism uses, the process that gives out oxygen. Aerobic metabolism takes long time to evolve(if impossible to develop by evolution alone), and if that happened in somewhere outside of bacteria...... expect to see a lot of deep oxygen sources and oxygen generator that does not depend on the sun. [Answer] Recently scientists have discovered two separate species of microbes that use two independently different novel metabolic pathways to produce oxygen without photosynthesis. So it might be possible for non-photosynthetic plant on your planet to produce oxygen without photosynthesis using one or a combination of these two pathways. Here’s two articles on these microbes, if you’re interested in having a read for inspiration: <https://www.sciencedaily.com/releases/2022/01/220106143640.htm> <https://www.mpg.de/bacteria-produce-oxygen-even-without-light> ]
[Question] [ I'm building a map of a fantasy town and its surrounding area. I'm using Campaign Cartographer (CC3) for this and I'm striving for appropriate scale. I know that, nowadays, the average outside wall thickness is of 30cm (12 in) while the inner wall range 10-20cm (4-8 in). Unfortunately, this average thickness is much influenced by AC usage and my folks have yet to invent AC, so cm is (mostly) off the table. Therefore, I have looked into the past. I know castle walls average 2 to 6 metres (7-20 ft), but that thickness is likely influenced by their defensive requirements so, again, I believe those numbers to be misleading and, therefore, they're also off the table. Question: How thick with the outer walls be in a regular house made of... * stone * wood * adobe Is there a pattern that would determine the increasing thickness of outer walls in houses with several floors? For instance, would a two-storey house have walls with the double thickness of a one-storey house? [Answer] ## It Depends I'm not sure if this will be of any help, but I assume this would change depending on what other materials were used in the walls. For example, if the culture has metal nails, that might change things. On earth today, modern societies can still build very large structures using these materials. For example: * The [tallest wooden building is 18 storeys tall](https://www.sciencedaily.com/releases/2016/09/160930145847.htm). * The [Great Mosque of Djenne](https://en.wikipedia.org/wiki/Great_Mosque_of_Djenn%C3%A9) is considered to be the [largest earthen building in the world](http://www.naturalhomes.org/great-mosque-djenne.htm). The walls of the Mosque vary in thickness between 40-60cm (16-24 inches), depending on their height. The eastern wall is [about a meter (3 ft) in thickness.](https://en.wikipedia.org/wiki/Great_Mosque_of_Djenn%C3%A9#Design) * The [Monadnock Building](https://en.wikipedia.org/wiki/Monadnock_Building) may be the tallest stone building. But, I doubt if such feats could easily be achieved 1,000, 10,000 or 100,000 years ago by all people of all economic classes, due to lack of computer-aided architectural planning, modern quality control of materials used, and all the accumulated architectural knowledge over time. Even if they could make it in previous times, they might need other advanced technology such as scaffolding, cranes, masonry, metallurgy, etc. to make such building possible. ## Materials Matter With all three materials, I assume the type of materials used would also greatly effect the thickness of the walls. For example, very weak woods like [balsa](https://en.wikipedia.org/wiki/Ochroma) would need to be very different thicknesses than woods made of [Australian Buloke](http://www.hitchcockandking.co.uk/h-k-news/top-10-hardest-woods-world/), which is considered to be the strongest wood on earth. The same would apply to stone: walls made of [talc would be different thicknesses than diamond walls](http://www.gemselect.com/gem-info/gem-hardness-info.php), or granite vs. limestone. With adobe, I imagine the same would hold true. However, I did find this quote about [adobe building code in the US](https://en.wikipedia.org/wiki/Adobe#Material_properties): > > Adobe walls are load bearing, i.e. they carry their own weight into the foundation rather than by another structure, hence the adobe must have sufficient compressive strength. In the United States, most building codes call for a minimum compressive strength of 300 lbf/in2 (2.07 newton/mm2) for the adobe block. Adobe construction should be designed so as to avoid lateral structural loads that would cause bending loads. The building codes require the building sustain a 1 g lateral acceleration earthquake load. Such an acceleration will cause lateral loads on the walls, resulting in shear and bending and inducing tensile stresses. To withstand such loads, the codes typically call for a tensile modulus of rupture strength of at least 50 lbf/in2 (0.345 newton/mm2) for the finished block. > > > ## Environmental Factors This might not be exactly what you are asking about, but in a sense, it might not be able to be avoided in a natural setting, namely other needs the wall must meet. For example, most walls need to do more than just hold up the roof or second floor. As you mentioned, medieval walls needed to provide defense, and modern walls need to house electrical wiring. If the building is in a very cold climate, insulation may be needed, and so if the insulation is placed inside the walls, that could change structural requirements. Or, as you mentioned, defense against hostile entities historically has changed walls. Or, earthquake prone regions would require different styles of walls. Frequent flooding, excessive heat, high winds, etc. would also effect wall structures. [Answer] 12th-century building regulations in London specified 3' thick walls when built of stone, though by later centuries stone party walls (walls held in common with several other buildings) being built 2' thick. For houses built of timber, thicknesses varied, but the principle posts tended to be ~10-12" thick. A half-timbered house wouldn't have had walls thicker than its principle posts, so that's probably your thickness. <https://www.arct.cam.ac.uk/Downloads/chs/vol7/article1.pdf> [Answer] Some decent research material can be found here: <https://euroasia-science.ru/istoricheskie-nauki/about-household-buildings-medieval-rural-settlements/> I really like @Thom Blair III's answer. Some additional thoughts on that... "It depends" speaks volumes. Rather than trying to add realism to your town by getting the wall thickness "exactly right", consider the context of the town, which is likely more important. What local resources are available in abundance? Wood, stone, clay. Are we building wooden walls from trees stuck in the ground or do we have a lumberyard making planks of wood? Wooden planks in medieval times were certainly available, but not necessarily to the average peasant, due to cost. Wealthy homes probably aren't constructed the same as peasant homes. Is this a secure town protected by a nearby castle that peasants will retreat into? If that's the case they may not have the need for thick stone walls on every home. If the town is constantly ravaged by raiders, the average home is more likely to be defendable. Is the town in a hot or cold climate? Thick stone walls = AC. For those with the means, thick stone walls were a large part of your home cooling. Thick stone traps cool air during the morning/evening and protects from the sun during the harsher hours. Stone is also always valuable as protection, but if you're in a cold climate and protection is not vital, you're likely to use something kinder on your bare feet at night. Wind zone courtyards and even fountains contributed to air cooling Roman homes. So, these techniques were understood even before medieval times. Architecture is and has always been driven by context. If the construction choices, materials used, and city layout make sense in the context of the land, politics, threats and local resources, your town is going to make more sense than if you simply justify it with historical data. Maybe your town has exceptionally thick or thin walls compared to others in the kingdom, just make it for a good reason. ]
[Question] [ I would like to have a humanoids with three pairs of eyes placed on the same horizontal plane like in [Protheans](http://masseffect.wikia.com/wiki/Javik) not one below the other like [Batarian](http://masseffect.wikia.com/wiki/Batarian). I was thinking of one pair being sensitive to our visible light, other to near infrared & third to near-ultraviolet, but it's not necessary if it doesn't make biological sense. This is predatory not prey species so binocular vision is paramount. How to justify why the evolution decided to select for three pairs of eyes? [Answer] Maybe early on in their evolutionary branch the creature had 3 sets of fairly primitive eyes. Pray species adaptation and maybe moving more subterranean made selective pressures focus on infrared for hunting but They also produce a chemical visible in ultraviolet for mating display so 2 sets of their eyes specialized in different ways. Maybe the center eyes stayed fairly primitive until they became more surface focused. They still have the mating display and still are night hunters but the branch that becomes more humanoid also stays active for part of the day and selects for stronger human visible spectrum as well. [Answer] Animals see "visible" light via rods and cones, and humans have 3 different types of [cones](https://en.wikipedia.org/wiki/Cone_cell) to see different wavelength ranges (i.e., colors) of light. Tetrachromacy is condition where an animal has four different types of cones. This fourth type of cone does not expand the visual spectrum, but can allow better discrimination of colors within it. So. @AndreiROM wonders why you couldn't fit all 3 sets in one pair of eyes, and the answer to that is simple: real estate. Eyes are packed full of as many rods and cones as can fit. While there's 3 (or 4) types of cones, they all sample a narrow, overlapping spectrum. If you wanted to pack two more wavelength ranges in, you'd have to cut your cell density for each spectrum to 1/3. Or, have different pairs of eyes. But, this creates significant problems. First and foremost, 3 independently functioning eye pairs means 3 independently functioning visual cortices in the brain. The visual cortex is a significant proportion of the brain, so replicating it a bunch is going to make things pretty screwy. Even with two eyes, our cortex has a tendency to cheat and only actually process one eye and only occasionally sample the other. So, we cheat. One visual cortex. Slightly expanded because some additional complexity is unavoidable. But, we only use one pair of eyes at a time. That way, the cortex won't get overloaded. Since we're on completely separate wavelength ranges, having all three overlap at once wouldn't be terribly useful anyway (it would be like looking at one of those 3D eye puzzles when you haven't seen it yet). Why would they overlap? One visual cortex; this is the price we pay for not being a bobble-head. This adds some interesting elements to the system. Under normal circumstances, one of these humanoids would only have one set of eyes open at a time, and the other two closed. This is because having unused eyes closed protects them, and it's also the simplest "off" switch. It also gives them the ability, in certain, very specific circumstances, to open multiple sets and overlay the information, if that does become advantageous. Imagine trying to code break a message that requires you to see in 3 wavelength ranges at once when you have just the one pair of eyes. But now we're back to... why do they need three sets of eyes to begin with? Visual wavelength ranges are certainly a possibility, but you'll need to find a dire biological reason for them to need eyes that can see in those wavelength ranges. Maybe there's areas of poison gas that can only be seen in ultraviolet. Maybe their prey can't be seen at night except infrared. Anything that can only be seen in a particular range and seeing it would vastly increase either survival or mating chance will exert evolutionary pressure on developing a system to see in that wavelength range. While they are predators, something to consider is that there are very few species that nothing kills, particularly since most species are willing to kill members of their own species. That means defensive abilities are still important. In this case, whatever the outside set of eyes, those are your "prey" eyes (the eyes that are most useful when something is hunting you). They have a much wider field of view, but much smaller binocular overlap, which means they're good at noticing things from more directions, but bad at focusing on them. There are alternatives, most notably [spatial frequency](https://en.wikipedia.org/wiki/Spatial_frequency#Visual_perception), but either way would work if you apply the appropriate evolutionary pressures. [Answer] More eyes are useful for gaining a wider field of vision. A great way to consider why an organism might evolve a specific trait is to look at other animals that already have that trait. For extra eyes, we have a fantastic real work example: spiders. Spiders all have four pairs of eyes, for a total of eight. However, not all spider eyes are created equal. In hunting species, like jumping spiders, a single pair of eyes are used as the dominant visual organs for spotting prey. These eyes are larger and more developed, giving good detail of prey animals for the spider. However, the spider's main eyes have a relatively narrow field of vision, which is bad when you're fairly small and other things think you're tasty. Spiders make up for this by having other, less developed, eyes to enhance their field of view. These additional eyes are set wider apart, which is bad for binocular vision, but great for spotting big things coming to eat you. Interestingly, researchers have found that spiders specifically react to threats when they [perceive them with these additional eyes.](http://www.livescience.com/24054-why-spiders-have-eight-eyes.html) In two eyed animals, on the other hand, eyes can be specialized for either binocular vision, like in hawks, or for a wide visual field, like in deer, but not both. While humans evolved from two eyed animals, it's perfectly reasonable that humanoid aliens could have evolved from a smaller creature possessing more eyes. These eyes would remain useful for increasing peripheral vision as the ancestral creatures evolved into increasingly complex forms, especially for small hunters for whom both prey spotting and predator evasion were important. In an environment with lots of big predators, such as the Cretaceous Earth, additional eyes used in this way would continue to confer an evolutionary benefit, even for organisms as large as humans. [Answer] I don't know how much sense do near-infrared eyes make, from what I know snakes sense infrared with their pit organ, but if they do work then maybe [Heralds](http://sto.gamepedia.com/Herald) evolved to hunt three distinct types of pray: 1. Animals that glow in the [ultraviolet](https://www.wired.com/2013/11/arthropods-are-having-a-secret-rave/) like [Scorpions](http://blogs.discovermagazine.com/notrocketscience/2011/12/23/why-do-scorpions-glow-in-the-dark-and-could-their-whole-bodies-be-one-big-eye/#.V_6Q4Oh96hc) 2. [Warm-blooded animals](http://www.icr.org/article/closer-look-at-how-pit-vipers-see-heat/) that are active at dark (infrared vision) 3. Daytime prey - normal eyes Even foraging plants that could easily be spotted only under UV could improve your survival chances, for example[Reindeer](https://www.newscientist.com/article/dn20519-reindeer-gained-uv-vision-after-moving-to-the-arctic) developed UV vision in the arctic. So if all those food sources provided ample calories to pay for the extra pair of eyes, and it was more advantageous to keep going after all of them, then I guess it seems plausible that some creature evolved to use them, especially if as @Tathel said its ancestor started with set of 3 relatively simple eyes. If they're horizontally placed it's interesting to know which ones are the closest ones to the nose, I assume it's the heat vision, with ultraviolet on the outer edge. Anyway they would make an interesting artwork. ]
[Question] [ What's the minimum safe distance to start building if you don't want any part of the shell or swarm to fall into the event horizon? Could you build a stable structure just short of the Schwarzschild radius or would you need to move farther back to be safe? How much farther? Could you build a shell only a few thousand kilometers in diameter around a relatively small black hole, or would millions of kilometers be the minimum safe distance? [Answer] The main use of building a Dyson swarm around a black hole would be to capture the energy released by its [accretion disk](https://en.wikipedia.org/wiki/Accretion_disk). This is actually a rather efficient way of producing energy, since it can turn up to [40% of the rest mass](https://en.wikipedia.org/wiki/Black_hole#Accretion_of_matter) of matter in the disk into radiation, much better than nuclear fission or fusion. You don't want the elements of your swarm colliding with the accretion disk, so they will need to orbit well clear of it, much farther out than the minimum orbital radius. You'll also have to arrange for occasional gaps in the swarm to allow more matter to be fed to the accretion disc, but that is much easier than the other challenges of this project. Those include: 1. Accelerating your swarm elements to orbital speed, which will probably be at least 0.05c. 2. Keeping space fairly clear of debris in the area. A relativistic [Kessler cascade](https://en.wikipedia.org/wiki/Kessler_syndrome) is going to be a horrible problem. 3. Converting all those hard X-rays to some form that's easier to transmit or store. If you transmit it, relativity makes that complicated; if you store it, you have to lift it out of the black hole's gravity well. [Answer] The minimum safe distance for components of a dyson swarm will be determined by the maximum safe orbital velocity for the individual units of the swarm. This is then dependent of the capacity of this world's technology, For example, if the maximum velocity attainable is half the speed of light, then the dyson swarm will be orbiting the black hole with an orbital velocity of approximately 0.5 c. Now you need to factor in the mass of the black hole and will yield what may be the minimum safe distance (assuming there are no other factors to endanger the dyson swarm). NOTE: This answer has limited itself to considering a possible minimum safe distance for a dyson swarm and not a dyson shell. Building a dyson shell around a black hole comes with a plethora of additional and probably intractable problems which need to be solved before even beginning to consider what constitutes a minimum safe distance. EDIT: There will be a component of velocity due to the black hole's gravitation. If their maximum attainable velocity is one-half lightspeed, the dyson swarm units will be able to boost away from orbit around the back hole, if they need to (just think of it as an additional safety feature). If space vehicles can accelerate to whatever their maximum velocity is, they will also have the capacity to decelerate too. [Answer] A Dyson shell is (unfortunately) impossible to build. Nothing with structural strength high enough exists, and it would require continual adjustment to not fall into the star/black hole. However, a Dyson swarm could be built relatively close to the event horizon, albeit at the massive cost of accelerating the individual satellites to near-lightspeed to achieve orbit. Further out, it will be much simpler and easier, but require more materials. [Answer] " Dyson shell is (unfortunately) impossible to build. Nothing with structural strength high enough exists, and it would require continual adjustment to not fall into the star/black hole. However, a Dyson swarm could be built relatively close to the event horizon, albeit at the massive cost of accelerating the individual satellites to near-light-speed to achieve orbit. Further out, it will be much simpler and easier, but require more materials" answer to the above: construct the swarm to be inclusive of a repulsive gravitational field (similar the the astrophysical structure of a pulsar) oscillated/emitted from the swarm itself to sustain around the hole, additionally have each equipped with a laser based projection optical ray to catalyze the accretion disk for higher power achievement through absorption by the swarm. ]
[Question] [ The [Spriggan](http://elderscrolls.wikia.com/wiki/Spriggan) is a tree-like creature native to the Elder Scrolls, where they are often found in forests and groves. In appearance, a Spriggan appears to be made of entirely wood and a glowing source that the people claim as magic, they are also claimed to be tree spirits due to the fact that they are always found in areas that feature trees or other flora. There seems to be two variations of Spriggans as some walk on two legs, while others walk on four. Is there a realistic way that a Spriggan could evolve? Is there a reason that a Spriggan couldn't evolve? What evolutionary factors would support the Spriggan? A list of all of the Anatomically Correct questions can be found [here.](http://meta.worldbuilding.stackexchange.com/questions/2797/anatomically-correct-series/) [Answer] "Tree like" and "appears" seems to be the important bits here. "Glowing source" might be bioluminescence - this might be an organ similar to that that a anglerfish would have. This might either be 'part' of them, an object (say a glow in the dark gem) or some sort of parasite or symbiote. A healthy specimen may have a brighter glow. There's a condition called Epidermodysplasia verruciformis that causes people to have wood-like growths That said, keratin or chitinous armour that's fiberous and flexible would be useful as a natural defence. Think hardened versions of the mop-like fur of the [komondor](https://en.wikipedia.org/wiki/Komondor) semi flexible, layered armour that looks a lot like wood. You might have evolutionary splits between two basically primate/ape like creatures, say great apes and humans. [Answer] The spriggan is a giant bioluminescent insect covered in barklike layers of chitin. The spriggan has branchlike appendages with "leaves" at the end, which are biologically similar to wings like those of a butterfly or moth. The spiggan's third pair of limbs are hinged behind their arms, and are covered in spikes to use as weapons. ]
[Question] [ I'm making a species which has a gas-based circulatory system. How would one go about designing such a system, in which liquid blood is replaced by some kind of gas? What kind of blood vessels would it need, how could blood cells and hormones travel through the system, what kind of pressure would it need, etc.? To be clear, what I mean by a circulatory system is a closed system with a "heart" that pumps the gas and nutrients in it around the body like a liquid-based one. [Answer] If it lives under different conditions than we are used to, it could be a [supercritical fluid](https://en.wikipedia.org/wiki/Supercritical_fluid). That is, a gas that's so dense that it would be the same as what we think of as liquid. It doesn't actually have to be supercritical in that the gas is as dense as the liquid of the same substance. It could be truely a gas phase, but as dense as what we think of as liquid, say, water. Look at the [atmosphere of Venus](https://en.wikipedia.org/wiki/Atmosphere_of_Venus) for example. A fluid’s density in a closed system is what allows it to carry other particles. Pumping is affected by the ability of the fluid to be compressed. You want a heart-like pump, not a propeller screw, right? But making it a supercritical fluid would be really cool, and could use something like a phase change heat pump as a heart! --- [In general](https://en.wikipedia.org/wiki/Supercritical_fluid#Properties), gasses have a density of around 1, and liquids of around 1000. A supercritical fluid has a density of 100–1000, and a fraction of the viscosity of a liquid. > > In addition, there is no surface tension in a supercritical fluid, as there is no liquid/gas phase boundary. By changing the pressure and temperature of the fluid, the properties can be "tuned" to be more liquid- or more gas-like. One of the most important properties is the solubility of material in the fluid. > > > ![supercritical CO2](https://i.stack.imgur.com/9GTit.png) This gives a rich source of ideas on how material transport can work: pressure differences can make material go into solution or drop out. The lower viscosity compared to liquid and lack of surface tension means it’s easy to move through fine channels. It can diffuse much better than liquid, so it sounds like a good idea for circulation for the same reasons it is used in industrial processes (not limited like the trachaea problem for gas!) Of interest to you, see the section on [planetary atmospheres](https://en.m.wikipedia.org/wiki/Supercritical_fluid#Planetary_atmospheres). How about an ocean of supercritical water with ice on the bottom? Is that crazy enough? So you want a high pressure, and a high enough temperature so it doesn't just become liquid. The actual values depend on the fluid, and as explained in the article, you can mix fluids to get the point just where you want it. So the body might use blood that's right near the tip of the liquid/gas phase line, so its heart can induce a phase change in one direction and avoid it in the other, or exploit sudden differences in viscosity, to acheive pumping action. See also [Close to Critical](https://en.wikipedia.org/wiki/Close_to_Critical) by Hal Clement. His planet had an atmosphere/ocean near the critical point of water, but I don’t think he explored how biological processes could exploit that. --- # Spilled Blood — a vignette ⶼ hollered as much in surprise as in pain. He was drawing his bow and concentrating on the prey that they had been tracking all morning, when out of nowhere a ↭ attacked him! The ↭ is like a fat rope half a span long with a biting mouth on each end and a fin along its length edged in razor wire. One mouth grappled for purchase, teeth chattering against the tough scales on his drawn-back arm. Meanwhile the unusually supple body wrapped around the arm and the razor fin slid along the scales until it found an edge to catch on, slid under the scale, and sliced the skin. Blood spilled from the wound, in a short burst. The rivulet pulled itself together into small glistening globules, flung a span away from ⶼ and his attacker. The mess slowed after the initial impulse and hung in the air right in the middle of the path. The other two members of the hunting party quickly grabbed the ↭ by its heads, carefully unwrapped it, and tied it in a game bag. The oldest and most experienced of the party, ⶾ, tended to his bleeding friend’s arm with a preparation to more quickly stop the bleeding followed by a bandage. That left the youngster, ⷆ, to deal with the spilled blood. He dabbed at the arm with swabs, wiping and tossing into a small bag (part of the medical kit they carried) before it could evaporate. Then he had to deal with the initial spill. The blobs hanging over the pathway had already grown to three times the original size and turned to fuzzy ocre knots of air. To any carnivore or omnivore, blood usually smelled like food. But their own species’ blood smelled disgusting. So it wasn’t just concern over attracting preditors that motivated him, but instinct that spilled blood is bad to be around. Just the thought of passing it through his gills was nausiating. So ⷆ closed off two breathing intakes and breathed only at his back, and approached the rapidly evaporating spill with an empty game bag stretched between two arms. He flapped the bag up-down;up-down, moved a bit to the side and repeated. Again, and then closer in with a very careful left-right. The disturbance in the air reached the blood and ⷆ could see little whorls grab the knots and draw them out into twisted loops, only futher evaporating the drops. But then the entire area of the spill rolled over, smearing the blood into yellow fog, but rolled up into itself and not spilling further. Easier now that he could see the movement of the air, ⷆ carefully fed the vortex and sent it gliding away, several spans off the path and down to the underbrush. The wounded ⶼ was squatting low: his three leg tendrals were coiled into a tight triple helix with the three points brought together, forming a single point that touched the ground. The body poised low to the ground over the point. Likewise, his arm tendrals were folded neatly and close to the body. It was important to stop any bleeding before the high pressure caused too much blood loss, and this included shunting blood away from the extemedies. Shock, in other words. Knowing he was in good hands, ⶼ relaxed into a meditative state, to give the wound a moment to close and recover normal activity level quickly. The thick oil applied to the wound also aids quick recovery—by the time the cleanup was done and the medikit stowed, it was safe to move normally without fear of losing more blood. They continued on, without the meal for the village they had almost bagged. The ↭ was a small consolation prize, that would be kept for ⶼ alone. His family would prepare the meat in the least unappitizing way they could; eating it made a point and was not waste. The real value was in the inetable parts: Unlike most animals which had scales and scoots and other hard plates, the sinuous ↭’s hide produced a small piece of leather. The mouth bones and teeth were not favored for weapons but had uses in making certain tools, and the razorfin could be preserved and used as a tool in itself. The morning’s prey was long gone after the commotion, so the party started over, searching for tracks. The village still needed meat. [Answer] Insects on Earth have [trachea](https://en.wikipedia.org/wiki/Trachea#Invertebrates), but the wikipedia article mentions some of the problems with this. * They limit the size of the insect. With present-day oxygen concentrations, the diameter of insects is limited to a few cm. They can still be long and thin. * Trachea do not work for the transport of nutrients, etc. If one were to imagine gas tubes to carry nutrients, they would have to be a closed system under pressure to blow dust or aerosols through the body. Clots would be a real problem. [Answer] You could use some sort of a combustible gas (akin to glucose) padded with other gasses, some sort of a cellular organ would process this gas and produces energy. This would not be much different than our circulatory system. Cells like red or white blood cells could be transferred over this air. An interesting aspect could be not having a hearth but using lungs to circulate air around the body. ]
[Question] [ This question already has answers here: [Could a Dwarven Civilization Exist?](/questions/9947/could-a-dwarven-civilization-exist) (11 answers) Closed 7 years ago. How far underground, assuming we're talking about a secret underground "living area", could be hospitable for human life assuming you don't want to hit the mantle? Would there be a pressure difference, and if so, what equipment would be required at such a level? Would it be too hot or too cold down there? [Answer] ## Heat based limit The [TauTona Mine](https://en.wikipedia.org/wiki/TauTona_Mine) is the deepest mine on the Earth. It is a gold mine. Tip of the TauTona mine iceberg: [![TauTona Mine](https://i.stack.imgur.com/kG4P4.jpg)](https://i.stack.imgur.com/kG4P4.jpg) TauTona Mine: [![TauTona Mine](https://i.stack.imgur.com/zKkkX.jpg)](https://i.stack.imgur.com/zKkkX.jpg) ### Characteristics * Depth - 2.4 miles * Ambient Air Temperature - 55C (131 F) * Rock Face Temperature - 60C (140 F) If the air conditioning stops working, the ambient air temperature can kill the miners. On average 5 miners die every year in this mine. I assume that without active cooling, this is below the lowest inhabitable depth. *Less than 2 miles of depth* ## Oxygen/Carbon Dioxide Based Limit Underground there's very limited life able to convert our wastes ($CO\_2$, urine, & feces) back into forms that we can use. Although we have many mines located a mile or more below ground, all of these require air exchange to keep humans alive. ### Active Very deep & active mines require the use of active system to exchange air with the surface (e.g. fans & blowers) to keep the miners from suffocating. If your blowers stopped working for more than an hour or so, expect your population to begin suffocating. If you assume an active air handling system that never suffers failures, then keeping the air fresh is: *Not a limiting factor* ### Passive It should be possible to create a passive air exchange system using the dynamic pressure of wind passing over special chimneys and other techniques to exchange air with the surface, this probably limits the depth of the mine too. Without actually modeling such a system, I don't really know what the limit would be. One unfortunate fact is that $CO\_2$ gas is heavier than $O\_2$, so it will tend to settle to the bottom of your hole. If you assume a passive air handling system, then you're limited by the volume and forces such passive system can generate. The exact answer will depend strongly upon the details of the configuration so I can't give you an exact answer. **Unknown, but I would guess less than 1 mile ### Closed Loop Life Support If you built your secret place more like a permanent space colony which only needed the input of energy to keep it going, then this wouldn't be an issue. However, it does point back to the first part of the answer in which you still need to find a heat sink to keep the place livable. Getting energy isn't a problem, however, dumping your waste heat will become a problem at depth. My guess is the limits of your ability to dump waste heat will require you to limit your maximum depth even more than the open-loop environmental systems would. A closed-loop life support system would ensure that you would not need to place your secret hidey hole near the surface to maintain a supply of fresh air. My guess is 1 mile < your maximum depth < 2 miles** [Answer] ## At least 11km The main problem is going to be heat. Why not then use the largest naturally occurring source for cooling, the ocean? The [Mariana Trench](https://en.wikipedia.org/wiki/Mariana_Trench) is almost 11 kilometres deep, making the surrounding rock stay cool, so if you burrow your base only a little further down than that, the temperature is not going to be a problem. A pressure-resistant habitat can survive the pressure, as proven by the descent into the trench by [Jacques Piccard](https://en.wikipedia.org/wiki/Jacques_Piccard) in 1960, or more recently by James Cameron in [Deapsee Challenger](https://en.wikipedia.org/wiki/Deepsea_Challenger) in 2012. ]
[Question] [ The current Underwater tag challenge gave me an idea: What if the whole universe were actually liquid? To elaborate: How can a liquid universe come to life? Ultimately, I want to have a universe where the space between planets and stars is filled with liquid. I would like that universe to violate as few of the laws of physics as possible, though if violations are necessary, I'd like to know which ones. So: how, plausibly, could such a universe come to life? [Answer] Your idea greatly resembles [aether theories](https://en.wikipedia.org/wiki/Aether_theories). As such, they are very well consistent with the understanding of physics (and were absolute mainstream) up to the [Michelson–Morley experiment](https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment) of 1887 which strongly suggested the absence of aether; but even after that the [Lorenz aether theory](https://en.wikipedia.org/wiki/Lorentz_ether_theory) successfully incorporated some special relativity phenomena although based on the aether framework. However, in the above aether theories aether is, to quote Huygens, “an omnipresent, perfectly elastic medium having zero density” which makes it quite different from the liquid-as-we-know-it. On the other hand, it clearly might allow for a world consistent with pre-20th-century physics and maybe even able to incorporate some of non-relativistic quantum mechanics. A description of the electromagnetic waves as transmitted by the aether allows for a non-contradictory physics where some of the non-everyday physics effects like stellar aberration would have been different (cf. [aether drag hypothesis](https://en.wikipedia.org/wiki/Aether_drag_hypothesis) with references to the Stokes model). [Answer] For Average Joe, it is probable that "liquid" means "I can swim in it". That means that you can actually push the liquid away to make yourself move, by conservation of momentum. So your liquid needs to have a mass. That yields several problems : 1. If the liquid have a mass, it is attracted by other massive objects such as star. In order to still fill the whole universe, and not just be aggregated around stars (or at a larger scale around galaxies), it needs to be incompressible. At the same time your liquid must dilate as the same rate as the universe to always fill it (but I will not address this problem in my answer). 2. Planets moving through the liquid will push on it. Therefore, a planet is slow down by the liquid except if both travel at the same speed. That implies currents in the liquid. That kind of system could be stable only if there is no friction, otherwise the currents will slow down, and thus the planets. It would leads to the planets simply falling into their stars (and stars falling on the centre of their galaxies). So, your liquid needs to be frictionless. A partial conclusion is that you need a massive, incompressible and frictionless liquid. It does not looks like a big deal at first, but in fact it is. The problem is for the liquid to be incompressible. When you push on a liquid in real world, you create a compression wave in it, and since the compression/decompression process travelling in the liquid takes time, the wave propagate at finite speed (the speed of sound in the medium). However if the liquid is truly incompressible, the wave (i.e. information) will travel instantaneously, thus faster than light. Breaking relativity is probably not a good start. It is possible that due to this, any push on the liquid will leads to the displacement of an infinite amount of mass (and therefore being impossible), but I have not yet figured it out in details. In conclusion, to looks like a liquid for Average Joe, your interstellar liquid needs to breaks some laws of physics. Indeed, in our world a incompressible frictionless liquid is not possible. And this breaking leads to even greater breaking of physics, at least relativity, but it is hard to figure out exactly how much you will have to break. [Answer] For this to work, you're going to have to throw out gravity as we know it. If the interstellar fluid repels other matter, but not itself, other matter will form bubbles within it. Think what happens if you drip oil onto the surface of water - the oil forms round droplets, and if droplets come into contact with each-other, then they'll coalesce into a larger droplet. Depending on the precise nature of the boundary effects, you may be able to create sufficient pressure in a sufficiently large droplet of hydrogen in order to achieve a fusion reaction, as well as providing a force similar to that of gravity on the surface of a world. A universe of this sort would be quite different to our own. There would be no orbits as we know them; it is more likely that objects would move as a result of thermal convection in the interstellar fluid, and this movement could be rather chaotic. A world may be in motion relative to a star by virtue of being caught in a convection cell, with planetary rotation induced by boundary effects between neighbouring convection cells. An interesting quirk of this is that day length could vary considerably depending on the position of the world within its convection current, and it might be ejected from its current to another one at some point in time. The interstellar fluid may carry a significant amount of heat around a star, allowing for planets to be warm even on their dark side. Interstellar travel would be slowed to a degree dependant on the viscosity of the interstellar fluid, though it would also provide a medium against which a ship could push using propellers. It should also be possible to sail the convection currents. With a combination of these two methods, interstellar travel should be possible. [Answer] If you had a universe where [gravitons](https://en.wikipedia.org/wiki/Graviton) don't exist or mass doesn't make gravity, then you could have a completely liquid universe, without having to worry about pressure. Though how such a universe could form in the first place is a bigger problem. Ignoring that, it could be interesting. Planets could be rocky lumps with molten cores to warm the liquid like deep sea vents, which would support life around them. Having no gravity makes fluid dynamics problematic, since if the liquid got hot enough to boil, it would create a gas bubble that wouldn't go anywhere. This could allow for stars to operate to some degree, but not currents very easily. If this liquid had a freezing point in the single digits kelvin then "interstellar" space would stay liquid. You could travel between planets if you some insulation or a heat source. [Answer] A universe in which mass does not cause space time curvature is what you would need to have a liquid universe as you describe. Your liquid universe would be similar to the idea of flatland but with three dimensions instead of two. Also this universe would likely be closer to having thermal energy evenly spread through the universe making useful work more problematic as there would be less of a difference between the temperature of a life form or machine and the environment than in our universe. ]
[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 want to get a shuttle from place to place in a reasonable amount of time. Say, 6 to 8 hours maximum, with a short break at the midpoint to turn around. Assuming constant acceleration to midpoint and constant deceleration after that, what's the highest g-force I could sensibly inflict on my passengers without breaking them? I'm assuming that they're seated (or lying oriented in the most sensible way, etc) and strapped in throughout the journey. [Answer] [NASA Technical note D-337, Centrifuge Study of Pilot Tolerance to Acceleration and the Effects of Acceleration on Pilot Performance (1960)](http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980223621.pdf) pages 30 and 31 graph G-force tolerance over periods of time. These are the limits where the pilots can still function. They all show a clear downward trend over time. [![NASA Technical note D-337 - Figure 10](https://i.stack.imgur.com/yAoj6.png)](https://i.stack.imgur.com/yAoj6.png) The longest period of sustained G-force evaluated in the study is ~35 minutes at ~3.5 Gs in the less favorable "eyeballs down" position (ie. deceleration). [![NASA Technical note D-337 - Figure 7](https://i.stack.imgur.com/9djJl.png)](https://i.stack.imgur.com/9djJl.png) These provide an upper bound for tolerance. When extrapolating to 8 hours, please note the scales of the graph are logarithmic. [Answer] [This article](http://archive.wired.com/wired/archive/11.03/7g.html) talks about NASA experiment with increased g loads. Summary: they run 22h sessions the subjects were supposed to spend in a centrifuge, this included standing up every 4 hours. The writer of the article ran the session at 1.25g (with some dangerous medical situation). The guy before him managed 1.5g, but got ill at the end. It's not clear how much of the problems was because of the gravity and how much because of the Coriolis force. [Answer] No-one has yet mentioned the possibility of an acceleration tank. If a passenger is immersed in a strong rigid tank full of liquid with pretty much the same density as human tissue, the effective G-force is reduced to one depending on the difference in density between the liquid and the human tissue. We're mostly water, so water is a good match. Bones are denser, but bone and bone connective tissues are tough because that's their purpose. Lung tissue is probably the most vulnerable - it can't be filled with water, because we have to breathe air, and it's delicate. Shockwaves from large bombs kill by rupturing lung tissues. But do we have to breathe air? There are chemically inert chloroflourocarbons which can cary a large amount of dissolved oxygen. A rat can be submerged in such a liquid and can "breathe" it for a considerable time. I don't know whether it's been tried on humans (and if it has it may be classified secret). An emulsion of such a CFC in saline has medical approval as an emergency blood substitute for when no compatible transfusion is available. Anyway, I'd guess at something like 10G breathing air in a water tank and maybe up to 50G breathing an oxygenated CFC liquid. The weight penalty for an acceleration tank is very considerable (many times greater than a passenger or pilot), so the idea has never been practical in aviation or spaceflight. However, if there's a very cheap source of energy for propulsion, maybe it could then become practical. [Answer] [Making a planet habitable for humanoids: The planet](https://worldbuilding.stackexchange.com/questions/9944/making-a-planet-habitable-for-humanoids-the-planet) I put a small section in there on G-forces. Orientation is VERY important, some humans can handle up to 45Gs for short periods of time if they're positioned correctly (eyeballs in/on their back - heart-brain same level, spine supported, etc). Vibration is important too. If you're at the wrong frequency even low levels of extra G can be incredibly harmful. If this is a shuttle, and you've got your humans in cradled seats, properly oriented - then you can get a lot more out of them, than say fighter pilots, who experiences jerks, and turns - instead of being correctly oriented to the thrust axis. 6Gs are handled for something like 10m; because you can only handle 10G for around 1m. I'd guess a maximum of somewhere around 2G sustained for the 8 hours you're specifying (I don't think anyone has ever had the opportunity to test that duration, much less get us some type of average). And this wouldn't be halfway pleasant at all. I think if you're launching from the surface of a planet/gravity well, you're going to want to vary the thrust. A lot at the beginning, then give the humans a break, then go into a constant-sustained thrust regime. A lot of thrust, quickly will get you out of a gravity well, whereas lower thrust will take a lot longer to get you a smaller distance - depending on the technology, obviously. Of course this is going to be some near-magic technology you've got going on, as keeping that much thrust going for that long is difficult - 90% of a rocket's mass is propellant, and we've never done a SSTO. Easier to drop engines after use than to deal with complexities of different thrust needs. And you burn most of that within the first 2m30s (for the shuttle). Most rockets only burn at lift-off around 1+0.3G to sometimes 1+0.6G, because of engine-scale, etc. Which seems wasteful, as the longer you're in the gravity well, the more you've got to burn just to stay even. [Answer] Fighter pilots get to live through a tremendous 3g acceleration without breaking their bones, when they make sharp turns. Anything above 3.5g is expected to leave permanent damage to bones and sinews. The crew (if trained for space travel thoroughly) might sustain upto 3.5g without undergoing any permanent damage. ]
[Question] [ There exist numerous theories on why the Moon lacks a layer of air if any, however the main culprits are gravity and the lack of Geo-dynamo simply put the Moon does not have the necessary mass nor the appropriate core condition to prevent air from escaping if there is any in the first place. I shall spare you with the boring details, in short without magnetic field the solar wind can blow off any atmosphere on the Moon into space. Humanity simply won't leave the surface of Moon barren, in fifty years to a century time we would bring life to our only natural satellite. By then the lunar colonists will breathe not through their suits but the surrounding air which closely match Earth's composition, there is even an ozone layer to shield lunar inhabitants against harmful cosmic/solar radiations. Using early to mid 22nd Century tech how can we blanket Moon with lasting atmosphere similar to Earth's but scaled proportionately or rather appropriately? Good answer should allow a nudist to walk his/her rabbit on lunar surface without much difficulty for at least an hour. Outstanding answer must address how can the colonists combat lunar typhoons. [Answer] The only way to realistically blanket the moon with air would be to cover the entire thing with some kind of biodome, unless you invent artificial gravity and/or manually increase the mass of the moon (which has substantial effects on Earth). You don't need a magnetic field, since it would take a very long time for the solar wind to strip the moon again (although it might make it a safer place to live). But without more gravity, the air on the surface will just evaporate into space. Further, even if you dumped a ridiculous amount of air on the planet, the lack of gravity means it won't be dense enough to breathe, even before it evaporates away. Then you have to deal with temperature. That's relatively easy. You need to get enough $CO\_2$ or something to store the heat from the light side of the moon while you're in lunar day. Except the lunar day is around 28 Earth days, leaving extreme temperature differentials. So you'd have to either build giant fans to constantly circulate the air and keep convection going, or make the moon start spinning a lot faster. Now, before you start all that, typhoons couldn't start, because those are caused by different linear speeds at different latitudes, and the moon doesn't have nearly the differentials Earth has. But if you have enough airspeed to keep convection going, the winds would be hundreds to thousands of miles an hour, making anything on Earth look like a dust devil. So the only option would be to spin the moon itself faster. According to [this page](http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html), the moon's $C\over MR^2$ is 3.929. We can multiply by its mass and radius squared to get $C=3.929\cdot 10^{24} kg\cdot (1738.1 km\cdot {1000 m\over 1 km})^2$$=1.2\10^{16} kg\cdot m^2$. Multiply by it's angular velocity squared, $\omega^2=({2\pi\over 27.3217}{rad\over day}{1 day\over 86400 s})^2$$=(2.662\cdot10^{-6}{rad\over s})^2$, and you get a rotational kinetic energy of $KE=8.41\cdot10^{25}J$. Do the same math for the new angular velocity and the energy is $KE=6.277×10^{28}J$. That's a difference of $\Delta KE=6.269\cdot 10^{28}J$. The sun's energy output is around $6.3\cdot 10^7{W\over m^2}$. Multiply by it's surface area, you get $3.797\cdot10^{26}W$$=3.797\cdot10^{26}{J\over s}$. If you could build a [Dyson sphere](https://en.wikipedia.org/wiki/Dyson_sphere), you could accelerate the moon in about 2 minutes. On the other hand, let's say we can "only" cover the entire surface of the moon in solar panels, and say they're 50% efficient at converting radiant energy into rotational kinetic energy. Now we have a total of $6.40 \cdot 10^{15} {J\over s}$. At that rate, it takes $9.80\cdot 10^{12} s$$=310,607$ years to get the moon going. So basically, every way we look at it, people on the moon will be living in small-scale biodomes for the foreseeable future. [Answer] Youd good* answer actually has to be outstanding as a nudist can't walk his rabbit out in the open with a huge typhoon dancing in the streets. Ahem. Anyhow. Lets begin. # Step 1. The Math! The first thing we would want to do is to make moon heavy enough to hold an atmosphere. As you already know, moon does not have any metallic core and is all rocking and boring and dead. But for that, we need some stats. Earth's total volume is 1.08 x 1012 km3 while the volume of it's metallic core is 7.61 x 109 km3 which means that in terms of volume, core : total = 1 : 142. The distance between core and crust of the moon (radius) is 3474 km which means it's volume is 2.19 x 1010 km3 . Now if we follow earth's example, the volume of it's metallic core would be 1.54 x 108 km3 which means that the diameter of its core would be 332 km. That is, out of a total radius of moon -3474 km- only 332 km would be it's crust. Which will do very little in terms of giving it a good magnetic field or increasing it's mass. Ha ha ha! # Step 2. Moon's Core OK, so now that we have the stats with us, we can get to do some heavy terraforming and geo-engineering and stuff. While earth's core is very little part of its total volume, we want the moon to have a larger core so that it may have a stronger gravity (don't worry, you'd still be jumping 60 feet in the air easily, kid). I suggest putting moon core's diameter at 1/5th of it's entire diameter. It will be much larger than earth's core ratio, but not mind bogglingly big. So, 1/5 of moon's radius = 3474/5 = 695 km. This is the radius of our moon core. Volume of moon core = 1.41 x 109 km3 This is a huge amount of volume if you ask me, when you want to fill it with iron and nick alloy. Where you get all that from, is none of my headache. What I would explain is how to place it at moon's core. First you'd need to dig a tunnel, at least 100 feet in diameter from moon's crust to its core. It's some 3474 km of digging. Don't worry though, you won't get fried by heat as our spies report that moon's core is dead. Nothing boiling or superheated present there. Basically you can just stockpile a huuuuuge amount of TNT based rockets (alongwith their supply of oxygen in their heads, as there's none on moon) and keep shooting them at one point on moon's surface. After you get to half a mile or so depth, you would need to take out the debris too. Also, you'd need to place titanium-steel alloy rings in this tunnel every 50 meters or so, to keep it from caving in. Gravity, you know, likes to shut all tunnels up. OK so, once you hit the 2700 km depth, start dropping hydrogen bombs there instead of your puny rockets. These big babies would do some massive damage and help loosen the astroundingly hard rock there which you would then need to crack and take out of the tunnel as usual. Once you cave in a hole ~1 cubic kilometer, quickly fill it up with solid iron and nickel pieces. Don't even think about pumping in liquid iron-nick alloy or you would be in for a world of hurt. Anyway, once you have replaced 1 cubic km of moon's rocky core with metal, blast another 1 km around it and fill it will with metal. Rinse and repeat till you have replaced 1.41 x 109 km3 of moon's core with metal. Congratulations! Mission complete! Moon now has a metallic core, making it somewhat heavier than before and also giving it a magnetic field (not as strong as it could have been if it was rotating fast enough, but better than nothing). Disclaimer: I am not responsible if all this core-changing stuff has a bad impact on moon's rotation or orbital speed etc. I have some fears that moon's added mass might make it a big too attractive for earth and ... (doomsday impact imaginations curbed). # Preparing For The Atmosphere OK, we have a heavy core now and we can afford investing an atmosphere on moon now. But should we do that right away like that? I guess not! Unless you want to be obliterated with dreadful cyclones, do not put an atmosphere on moon yet. First prepare moon for it! Moon has an outrageous temperature difference between night and day sides. In the absence of a temperature regulation system, this would cause horrible winds (speeds exceeding category 5 hurricanes on earth) which would blow everything apart. This would have been the same on earth, too, if we weren't blessed with the benevolent system of oceans which regulate temperatures very well. So if we get to get oceans on moon too, we can regulate the temperatures there too. Do you remember we blasted away some 1.41 x 109 km3 of moon's core? All that debris is laying on the surface now. And man, that's some huge mound, if you ask me! How about we start distributing it unevenly on moon's surface, so as to make 40% of it's surface higher than the rest? We have 1.41 x 109 km3 of debris while the surface area of moon is 151659455 km2. 40% of which is 60663782 km2. Doing a bit more of math shows that we can have a height of 7.5 km for this area if we spread the debris equally on it. That is far more than we require. I suggest we spread 6 x 108 cubic km of debris for raising this surface 4 km higher and use the rest of it to build lofty mountain ranges and stuff. Now we have a deep valley comprising 60% of moon's surface area at a depth of 4 km. How about we ... fill it water and create a lunar ocean? Woohoo! Then we could all go for a swim. Yay! OK, so ... I don't want to go through the pain calculating how much water volume that would make. Just take that water from earth's polar glaciers and throw it in moon's valley. You'd also be getting rid of that yapping of scientists and researchers of earth shouting sky high about rising sea level. Balderdash! # And The Atmosphere! OK, now we have very good temperature regulation system and we have a much heavier moon (don't forget the additional weight of water too!), so we can now start pouring atmosphere on moon. Make whatever atmospheric cocktail you want, and pour it on moon. Just make sure you keep the oxygen concentration ~40%. Much of it would be used up in the formation of an ozone layer, thanks to sun's ultraviolet beaming. So ... yeah. We are done. You can go on and have nude beaches on moon or whatever. Just make sure there's a far away cottage reserved for me on a secluded island somewhere in the middle of moon's ocean. [Answer] I believe the other answers given are not correct. Even a body with the gravity of the moon could hold a breathable atmosphere for a time that is long on human scales. The effects of the solar wind and of thermal loss due to molecules reaching escape velocity take time. It is also incorrect to say that the atmosphere could never be thick enough to breathe. Titan has a surface gravity similar to the moon, and has an atmosphere thicker than the earth's. Because the gravity is less, it takes a higher column of air to achieve that pressure, but it can be achieved. Part of the reason Titan has been able to retain that atmosphere over the history of the solar system is that it is much colder than the moon, and is less affected by the solar wind since it's much farther from the sun. But, again, time scales matter. I have not found a source estimating the exact timeframe for atmospheric loss, but I recall reading that it would take thousands of years or more. Here is an [essay on the topic](http://www.slate.com/articles/technology/future_tense/2014/07/terraforming_the_moon_it_would_be_a_lot_like_florida.html) by physicist and science fiction writer Gregory Benford. ]
[Question] [ I am making a sci-fi web-comic set on an alien world and I thought up an idea for an eye that works much like an eye from a mammal, but instead of moving the whole eye, only the pupil moves. This idea sprouted from the eyes of mantis, though their moving pupil is possible because of their compound eyes, I would like to know if my idea could be physically possible in a structural sense. [Answer] My first thought is of the "windsock" eye design of the anterior median eyes of a spider. [![spider](https://i.stack.imgur.com/1NTYB.jpg)](https://i.stack.imgur.com/1NTYB.jpg) (Emphasis mine) > > As the lens is attached to the carapace, the eye's scanning movements are restricted to its retina through a complicated pattern of translations and rotations. This dynamic adjustment is a means of compensation for the narrowness of the static field of vision. It is analogous to the way most primates move their eyes to focus images of interest onto the fovea centralis. Such movements within the jumping spider's eyes are visible from outside when the attention of the spider is directed to various targets. > > > This is actually the opposite of what you ask, but the same thing: the eye does not rotate as a whole object. If the pupil moved and the retina stayed fixed, how would that look any different from moving the whole thing? There are good reasons why the eye would not be a moving ball like ours. For example, birds have better resolution and for larger imaging area and stability of same has a flat back (not round; more like a camera film plane) and fixed to bone so it stays stable. An animal might evolve a way to pivot the primary lens, like a [view camea’s front board](https://en.wikipedia.org/wiki/View_camera#Movements), which has the added benefit of doing what a view camera can do with perspective and focusing on planes like a cliff face, all in focus at the same time. Landscape photographers use a tilting lens to allow more of the ground (at different distances) to be in focus — shouldn’t that be useful to an animal watching for dangers or dinner, just as well? ![camera](https://i.stack.imgur.com/DbXZy.png)![camera](https://i.stack.imgur.com/IeT0V.png) Now this is what you describe exactly. Look at why cameras do that, and design evolutionary pressures to exploit these same advantages. The independent motion of the lens and sensor plane gives abilities that are not present through moving the camera as a rigid unit. So, it may be selected for even if the lack of swiveling of the eye can be dealt with in a different way or the non-round rigid back was no longer a priority. [Answer] Sure it's possible but why would you do that? You want to meld this: [![Compound Eye Cutaway](https://i.stack.imgur.com/TMHGO.jpg)](https://i.stack.imgur.com/TMHGO.jpg) to this: [![Human Eye cutaway](https://i.stack.imgur.com/GGizR.jpg)](https://i.stack.imgur.com/GGizR.jpg) Making a stationary retina is certainly possible. Making a moving pupil may be possible too. The trick is getting them to work together. The control structures required to move a pupil around while maintaining focus on an immovable retina is far more complex than maintaining focus on a retina that moves along with the pupil. I don't know of any optical structure, natural or man-made that forces the pupil to move independently of the retina. The physics governing optics are very unforgiving. Getting them wrong means that your creature won't be able to see properly and thus won't survive as well as creatures with simpler eyes closer in design to our own. From an evolutionary perspective, it doesn't make much sense. A more complex eye is more prone to errors in development and less resilient to damage. A simpler, more robust eye (like our eyes or an insectoid compound eye) would do much better. [Answer] It took me a while to figure a way to this could happen and make some 'logical' sense. What I came up with is is the eye (rods cones or what ever sensors they have) are just on an immovable sheet some distance behind a lens like a movie screen. similar to how our eye works, but instead of the Iris and pupil being apart of the eye, the eye is set like the bones in the body, but the eyelid is the pupil opening and closing for more light, moving focus kind of like a telescope. They could also help 'flex' the lens to give a wider range of focus for the eye, looking real close and seeing very far away. ]
[Question] [ To clarify by flying ship I do not mean conventional airship. A lot of fantastical depictions of flying ships look like their naval counterparts but in the air. However these have features like underside hulls and sails on the top which wouldn't necessarily be optimal for a ship in the air. This is primarily a design question so lets just say the ship can float by magic so there are no gas bags. What would the sails or other propulsion look like? How would such a ship be designed in a case of battle, being vulnerable from three dimensions of attack? Overall how would the ship differ from their naval counterparts? [Answer] I came up with the concept for just such a ship once for an RPG. It did not require any "antigravity" to make it float either. CONCEPT The basic premise that allowed the ships to fly and navigate was that there was a magical "keel" material that would easily move back and forth along one axis, but was very much harder to move in any other direction, though somewhat less difficult to turn. Thus, by holding the keel material in a particular attitude and pushing, an entire assembly could be made to gain in altitude and manoeuvre under wind power. The performance parameters of the airship would depend on the amount of sideslip that the keel material allowed amongst other things. The ship itself, as I envisaged it, would be a hull shaped like a boat-tail rifle bullet within which cargo and the keel mechanism would be housed, with masts that hold the sails. It made sense that there would be masts on all sides of the ship, from two extending laterally. to three in an Y (upright or inverted), or four in an X or a +. Masts may also be duplicated moving back along the hull, thus 4 or 6 or 8 with two sets of masts, or 6 or 9 or 12 with three sets. The masts would carry spars, sails and rigging that would catch the wind. A Lateral-only mast plan would have the advantage that the masts would not interfere with landing greatly, while two sets of X- or inverted-Y- masts could act as landing gear if they were properly rigged and reinforced. MANOEUVRING The ship would be controlled by using two or more independently controllable keels, mounted in gimbals fore and aft at a minimum, though the more keels there are, the more stable the ship. Since the keels move easily in only one direction, and resist movement (relative to their environment) in other directions, steering can be accomplished by properly angling multiple keels. With both keels pointing slightly upwards, the thrust provided by the wind will cause the ship to sail along in level flight. Angle them further upwards, and the ship will climb, and angling them down will cause the ship to descend. Angling the fore and aft keels up and down independently can cause the ship to pitch, and angling the keels sideways can cause the ship to sideslip or turn. With more keels, say 4, the ship can also be made to roll. There would be issues of stability that would require constant trimming of attitude, though this need not be accomplished by the crew; the gimbals could be equipped with damped pendulums that would hang downwards in the local gravity, and could be used to automatically keep the ship in the correct attitude, and might even provide automatic banking so that centripetal forces would not lead to objects sliding across the decks, but would automatically bank the ship. Like any sail-and-wind-powered ship, there would be issues of wind speed and direction, necessitating tacking or wearing in order to sail upwind, and affecting military tactics. In such ships, altitude would be as important a factor as being to the windward of an enemy, as it is a factor common to both sail and our self-powered flight that altitude may be traded for speed. By reducing sail in order to reduce drag, and descending, a ship's speed will increase significantly, and speed can also be traded for altitude. Navigators will also have to consider local wind conditions, including updrafts and thermals, though they would typically have lesser tactical implications than altitude and wind direction. LANDING Landing would be a matter of descending, shedding speed by furling sails and correctly angling the keels (extra keels beyond 4 would help here) to create additional drag, and allowing the keels' inherent side-slip to gently lower the ship to the ground. Take-off would be a little more complicated - there would need to be landing gear that would be retracted to allow the ship to float freely long enough to gain sufficient headway for the keels to provide enough lift to climb. COMBAT Weapons Considering the weapons that these ships might carry, Age of Sail had as its best weapon system black-powder smoothbore muzzle-loading artillery. The shot used in this period was initially stone or iron round shot, and progressed to explosive-shell round shot with time-delay or impact fusing. It would also be reasonable to suppose that we could have black-powder gravity bombs with time similar fusing. Rocketry existed in the AoS, but was lightweight and inaccurate, and used primarily for night-time signalling. Weapon Emplacement Given the complexities of air-to-air combat with smoothbore open-sighted artillery, we could expect that most combat would occur either at roughly equal altitudes with artillery broadsides fired from long cannon or short carronades, or at high/low altitude, with unguided bombs and downwards-firing guns against high-angle guns. It would be possible to mount a smoothbore artillery piece so as to be able to fire steeply downwards, but this would require ramming the bore with a tightly-fitting wad over the shot to prevent the shot from simply rolling out. In addition, the gun would have to be loaded horizontally, then tilted downwards and primed in an rear-facing flash-pan or flintlock before being run out. A downwards firing gun would require a rather different gun carriage, which would allow the gun to be run in and out vertically yet still remain secured (We don't want a loose cannon) and able to be tilted for loading. The breeching would involve counterweights so that running the guns in and out by hand would be possible. Downward-firing guns would be slower-firing and heavier than broadside-firing guns or upwards-firing guns. Armour In the AoS, the primary armour material was wood, though some ships had double timber hulls with the space between filled with stone; these were less successful. AoS naval ships could have very thick wooden hulls, often several feet thick, yet this armour was also a liability, as shot that penetrated the hull would be accompanied by a spray of splinters which caused more crew injuries and fatalities than the shot itself. Short barrelled carronades capitalised on this, firing large, relatively slow (and short-ranged) shot that maximised splintering and crew casualties, as paradoxically faster, smaller, longer-ranged shot caused less damage to both ship and crew. Ironclad wooden ships occurred near the close of the AoS, and were nearly invulnerable to roundshot, driving the development of ogival shells. In the AoS, there were also varieties of shot designed to maximise damage to an enemy ships rigging, including bar shot and [chain shot](https://en.wikipedia.org/wiki/Chain-shot). As much combat would occur on a level or high/low, warships may be designed with diamond hulls that would more readily deflect shot from the same level or from above/below, though to be most effective, the ship would have to be rolled to present the plane passing through the points of the diamond toward the projected trajectory of the incoming shot. This may be effective in 1 on 1 combat scenarios, but in a massed battle, the flat faces of the diamonds would be more of a vulnerability than a defence, and it could be expected that heavy combatants designed for massed combat would have round cross-sectioned hulls, those being most likely to deflect a shot coming from any trajectory Battle Formation In the AoS naval battles, a common formation was the line of battle, with ships lining up so that if an enemy did manage to "Cross the T" (to pass in front - or less effectively astern - of an enemy ship with its broadside facing the smaller, less heavily armed bow or stern aspect), only the lead or trailing ship would be particularly vulnerable. To extend the line of battle from 2 dimensions on the sea to 3 dimensions in the air, we would have a wall of battle, with lines of ships stacked so that the broad side of the formation would face the enemy, most commonly vertically or horizontally, but angled walls would have their place in some combat situations. Neutralising Enemy Ships In combat, an enemy ship can be neutralised in several ways: 1. The hull can be broken to the point where the ship comes apart - this would be the most difficult outcome to achieve through gunfire alone. 2. The crew could be injured or killed to the point where the ship is no longer an effective fighting unit. 3. The ship could be set on fire, which would damage all the equipment and injure the crew, and in the worst case, could result in a magazine explosion that could destroy the ship. 4. The sails, spars, masts and rigging can be attacked, reducing manoeuvrability and speed, and ultimately resulting in the ship being forced to land or crash. 5. The keel gimbals could be damaged, resulting in a loss of manoeuvrability. 6. The keels could be dismounted or destroyed, resulting in a loss of 'grip' that would cause the ship to crash. Given that the keels would be the most important and vulnerable components of such a ship, it can be anticipated that in military vessels, the gimbals would be armoured in addition to any other armour the ship may carry. Air-Ground Combat In combat against ground installations, airships have a distinct advantage in that they can attack from high altitude, beyond the range of ground-based guns. However, accuracy at these altitudes would be low, and a great deal of ordnance could be expended for only a few good hits. There would be a balance between altitude and accuracy, and it is likely that larger, longer ground-based guns could make effective attacks at ranges not effective for ship-based upwards-facing guns which would be more limited in size and mass. Ground-based guns would also have the advantage that they could fire red-hot iron shot that would be highly likely to cause a fire in their target, however while this was an effective tactic in naval combat where misses would go harmlessly out to sea, in aerial combat, misses are quite likely to come back to earth and cause fires there, so this is more likely in coastal fortifications than those inland. Parachutes [Parachutes](https://en.wikipedia.org/wiki/Parachute) would be invented earlier; they are simple devices that could be invented in the Age of Sail with the correct impetus, namely airships. As an interesting note, in World War I, parachutes had been invented and were issued to personnel manning barrage balloons (and to German pilots), but were not worn by allied fighter pilots, as it was thought that they encouraged cowardice, and to encourage fighter pilots to fight to save their aircraft rather than bail out, they weren't issued. It may well be the case in some aerial warship forces that the crew are not issued parachutes so as to encourage them to fight rather than flee by the expedient of jumping overboard and trusting to their parachute. It may also be possible that the more highly trained officers and petty officers would be issued parachutes while common airmen would not be; it would all depend on the attitudes of their leaders. We can also expect that there may well be a branch of military service for [paratroopers](https://en.wikipedia.org/wiki/Paratrooper); ground troops deployed from aircraft. These troops could be deployed far more rapidly than marines from an AoS naval ship, who would have to rely on rowed boats. Conversely, we can expect that parachutes would be standard issue for merchant crews; a parachute and a delay for search and rescue could be cheaper than replacing a crewman in the event of a fall from the rigging. We can expect that ram-air parafoil parachutes would be rare even after their invention. In a military situation, they provide too much manoeuvrability that would lead to the excessive dispersal of a mass-drop of paratroopers, and they are more complicated to use and train than round 'chutes. Their primary use might be in small special-forces drops. [Answer] Sailing ships on water depend on the interaction of sails in the air and keels in the water. The difference in movement between air and water can be turned into movement in almost any direction, except for directly upwind. An aerial sailing ship with both sails and keels -- or just sails -- in the air wouldn't have this difference to generate propulsion. It would drift with the wind. You might get something like [dynamic soaring](https://en.wikipedia.org/wiki/Dynamic_soaring) or an aerial equivalent of [underwater gliding](https://en.wikipedia.org/wiki/Underwater_glider), but that changes the appearance of your ship. Wings, not sails. [Answer] This type of ship could evolve, without magic, from water-based ships whose sails evolved gradually into parafoils. [![enter image description here](https://i.stack.imgur.com/kWzJe.jpg)](https://i.stack.imgur.com/kWzJe.jpg) Sails would evolve into spinnakers. [![enter image description here](https://i.stack.imgur.com/42T17.jpg)](https://i.stack.imgur.com/42T17.jpg) Then spinnakers would evolve into kite-surfing wings. Ships would have multiple sails, each a parafoil. It would require one or two crew members to control each sail. [![enter image description here](https://i.stack.imgur.com/dNFHS.jpg)](https://i.stack.imgur.com/dNFHS.jpg) The ship would take off from the shore-line using the updraft from the onshore breeze. [![enter image description here](https://i.stack.imgur.com/McPW9.jpg)](https://i.stack.imgur.com/McPW9.jpg) Once it had reached sufficient height it could make long journeys across the sea or land using ridge lift and dynamic soaring. > > Technical > > > [Ridge lift](https://en.wikipedia.org/wiki/Dynamic_soaring) (or 'slope lift') is created when a wind strikes an > obstacle, usually a mountain ridge or cliff, that is large and steep > enough to deflect the wind upward. > > > If the wind is strong enough, the ridge lift provides enough upward > force for gliders, hang gliders, paragliders and birds to stay > airborne for long periods or travel great distances by 'slope > soaring'. > > > [Dynamic soaring](https://en.wikipedia.org/wiki/Dynamic_soaring) is a flying technique used to gain energy by > repeatedly crossing the boundary between air masses of significantly > different velocity. Such zones of high wind gradient are generally > found close to obstacles and close to the surface, so the technique is > mainly of use to birds and operators of radio-controlled gliders, but > glider pilots have occasionally been able to soar dynamically in > meteorological wind shears at higher altitudes. > > > Notes > > > [Paraglider](http://www.dailymail.co.uk/news/article-2385323/Paragliders-longest-flight-record-set-7hr-flight-American-West.html#ixzz3hAU4YhmC) sets record for longest flight with incredible 240-mile, > seven-hour flight over American West > > > [Wandering albatrosses](https://en.wikipedia.org/wiki/Wandering_albatross) spend most of their life in flight, landing > only to breed and feed. Distances traveled each year are hard to > measure, but one banded bird was recorded traveling 6000 km in twelve > days. > > > EDIT In response to a comment. > > The largest parafoil ever flown has successfully glided down to Earth. > The parachute had a span of 44 metres (143 feet) and a total surface > area of 700 square metres (7,500 square feet). This area is almost one > and half times bigger than the wings of a Boeing 747 jumbo jet. > <http://news.bbc.co.uk/1/hi/sci/tech/634187.stm> > > > ]
[Question] [ For my science-fantasy I'm building nation that is governed by guilds,this country is loosely inspired by the concept of Anarcho-syndicalism. The governing council Is made up of the Grandmasters of the guilds that are the most vital to the nation. However I don't know what industries or service are indispensable to a country. So I ask that question here... What are most the vital industries and services to a country? [Answer] I think that you can see it from a need perspective. If there is a need for it, there will be an industry to fill it up. And then it depends on the environment where your nation will be located. As a starting point, you could look at [Maslow's hierarchy of needs](https://en.wikipedia.org/wiki/Maslow%27s_hierarchy_of_needs), ![Maslow's triangle of needs (from Wikipedia)](https://i.stack.imgur.com/pxHYX.png) And then depending on the evolution of your nation, you try to satisfy as many needs as possible. * The first industry needed is the food industry. Indeed people need to eat. For that, you have to consider the level of development your nations lives in. You need food production (agriculture/animals/fishing) to provide raw materials. You might consider distribution and trade, to get from the production centres to the consumption. And if you have a larger population, or need larger travel, you might consider the food transformation industry: from basic one: using ice/salt, to industrial ones: cans. Once you are sure that people eat (enough), you can consider other industries. They also probably don't want to go around naked. It might be cold, so clothing industry is probably needed to some extend. Similarly, they probably won't feel like sleeping outside. If you have cities, you need material production (wood, metal, etc.) as well as building industry (bridges, transportation, houses, etc.). * If people are fed and dressed, they want to make sure they will not die just getting out of their home. This require a form of justice and police. Possibly military as well if you fear attacks from outside. The form those take could clearly vary between nowadays (relatively-)safe societies, to a tribe chief and warriors enforcing the decisions of the chief. It depends on how far is your society advanced, but maybe a system of health: hospitals, doctors, pharmaceutical companies, etc. could be considered. With that you probably have the very basic needs covered. You might want to consider a few more services to facilitate the previous ones: * Education to get people ready for your industries. * Communication to get information from one to the other. It could be a simple postal service, or you could have internet/radio/TV/etc. * Entertainment, this has always proven useful to maintain a certain equilibrium (think about Caesar's [Bread and Circuses](https://en.wikipedia.org/wiki/Bread_and_circuses)). * Banks, well you might want to have a currency system to support the trade of goods. If so, you need to produce said currency, exchange, move it, give it value etc. If the people are fed, clothed, feel safe, healthy and entertained, they probably won't break everything havoc. So that should probably be enough for a start. Following up on Jim2B comment below, one has to consider the evolution of the society and/or tech-level. In prehistoric time, food industry were hunters-gatherers, clothes industry was done with at best some animals skins, housing were at best caves. So in early time several of those industries were combined. As time changes different people starts to fill in different roles and further on more specialised on sub-industries. And of course, the different industries become inter-dependent: you need machines to tend your crops, transports for your army, etc. And metal, metal industry and distribution for all of them. So your guilds are inter-dependent. [Answer] Keep it simple: The great table had only 10 seats. 9 of the seats had a glittering actuated paining behind it, representative of their Guild's Arms. 1. At the right of the table, second in command, in the position of honor, sat the Guildmaster Arkan Mavek, from the BP-Shell-Greenpeace-General Electric guild. The painting behind him dynamically depicted the sun being worshiped, the sun caught in pervoskite electric cells, the sun caught by plants and turned into black oil and coal, the sun triumphant. 2. To his right, sat Guildmaster Belmont Varneil, from the Seers Guild. The image behind him depicted a great eye, with satellites in the sky, insect-sized sensors on the ground, cameras blanketing the large cities, and a great weaving current of analysis sweeping thorough it all. His face seemed permanently shaded, in that it seemed impossible to make out any of his features with any clarity. 3. To the left, sat the High Mother Fatima III, of the Born Again Disney Islamic Faith. The black and green fluttering flags behind her were superimposed on images of Orney the Horny Badger and indicated her guild's leading role in the realm of Indoctritainment. 4. Tim Hanks, from the Monsanto and Clearwater guild, sat smugly in his seat, with a background of monstrously large crops, and gigantic meat-growing labs. 5. Enver Hodgea, of the Albanian Mafia, was next. By him were images of large infrastructure projects, from space elevators to highways and other megastructures. 6. Vladimir Rogojean sat for the Peacekeepers, whose blue helmets featured prominently in the short videos showing the military forces machine-gunning attempted illegal immigrants and burning enemy villages. 7. Lataya Merero, of the Blue Crescent, had a background indicating her guild's affiliation with hospitals, nurseries and primary schools. 8. Proctor Zakharov, of the University, was head of Northern Planetary research and all the higher education efforts, wearing the disturbing implants that were typical of AI-enhanced researchers. 9. George Grigoropulous was in charge of the Transit Authority, with a fleet of megaships, airdrones, maglevs and zipcars all zooming in the background behind him. 10. At the head of the table, in the chair of absolute command, sat Ramil Bihnev of Goldman Sachs. There was no background image behind him. [Answer] The wants and needs of people are covered by the guilds, but the guilds themselves will need some sorts of mechanisms to define their rights, protect their property and arbitrate disputes between themselves, as well as between guilds and customers. For most societies these have been provided by the State and both classical liberal thought (represented by such thinkers and Edmond Burke and Adam Smith) and modern Minarchist Libertarianism stress the importance of these (Individual liberty, freedom of association and speech; unfettered property rights, and the Rule of Law. Libertarians draw the line there, while other political philosophies try to add to the list, or more ominously, remove them). Since you are looking at Anarcho-syndicalism (or perhaps the close relative Anarcho-Capitalism), there will be no State to provide protection of these rights. Much of what I have read about this philosophy suggests that there will be competition between private service providers to deliver protection of individuals and their properties, as well as some sort of arbitration service (once again with multiple arbitration companies competing for business). In this world, there would then be a Police and protective services guild (possibly including EMS and fire protection) and an arbitration guild. In the real world, this would likely resemble Europe during the Dark Ages, where central authority had broken down and local lords competed for power with their own private protection services (aka private armies) and arbitrated disputes on their own land as they saw fit. If my guild can afford to hire a larger and more aggressive "protection service" to advance our aims, and bribe the arbitration guild to settle things our way, then there is little to stop us from doing so. ]

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