text
stringlengths 22
2.11M
|
|---|
[Question]
[
Early on in the cartoon *The Legend of Korra,* we're shown one of the main characters working at his job. He works in a power plant, where he and his coworkers spend all day using Bending (essentially elemental magic) to conjure up lightning bolts and throw them at some sort of machine, to produce electric power for the city. But as interesting of a concept as it is, actual electrical systems depend on steady, predictable current; surges (such as the kind brought on by a lightning strike) tend to destroy electrical machinery.
Is there any way to make this system practical? Assuming the existence of a world with all the same physical laws as ours, but where elemental magic exists that allows for people to conjure up lightning at will, would it be possible to create such a power plant? And if so, how would it deal with the highly uneven current?
(Yes, this is tagged [science-based](/questions/tagged/science-based "show questions tagged 'science-based'"). Yes, the [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") tag says no magic. The question isn't about the magical side of it, but the physical side.)
[Answer]
**Not very realistic.**
HowStuffWorks has [an interesting article](http://science.howstuffworks.com/environmental/energy/harvest-energy-lightning.htm) about generating electricity from lightning. There are several problems with harnessing natural lightning:
>
> The logistical problems involved in making it work are significant. First of all, there's the basic fact that thunder storms are sporadic and lighting strikes random; considering that energy demands are steady, dependable energy sources are preferable.
>
>
> Second, it's not so easy to capture energy delivered in one enormous blast in a split second. It has to be stored and converted to an alternating current, without blowing out the collection system in a single large strike.
>
>
> Third, the energy contained in a lightning bolt disperses as it travels down to Earth, so a tower would only capture a small fraction of the bolt's potential. In the end, barring the development of a technology that could capture the energy from lightning before it strikes, it's probably best to focus on other, more earthly sources of energy.
>
>
>
The first point should be irrelevant here because the lightning can be activated at precise intervals. The third is unimportant because there should be no dispersal (I assume that this scenario takes place on short ranges). It's the second that is an issue. Capturing 5 billion joules in one second isn't easy. Perhaps if this is on a smaller scale, it could be plausible.
With better technology (i.e. capacitors for energy storage), this could happen, but it would take a lot of improvements. In the meantime, there's a chance that you could take advantage of atmospheric effects, such as [this proposal using water vapor](http://www.technologyreview.com/view/420522/generating-power-from-electricity-in-the-air/). I don't think that the manmade bolts would have the same sort of effect, though, because the environments are different. Perhaps you could try harnessing the [thermoelectric effect](http://en.wikipedia.org/wiki/Thermoelectric_effect), or use the lightning bolt to turn water into steam, turning a turbine.
Indirect energy capture is probably the best option here.
[Answer]
So long as the electricity can be captured, **yes**, it could be feasible. The unevenness of the current could be addressed the way we do it in the real world. For example, using the energy from the bolts to power pumps that move water up to a reservoir. The water in that reservoir then powers conventional hydro-electric generators for steady and adjustable power generation. You can get upwards 80% efficiency with such a storage system. Though perhaps it would be even more efficient to use magic to move the water directly.
[Answer]
They could use their electricity for the electrolysis of water, to capture the energy. Would be environmental friendly
] |
[Question]
[
[Tachyons](https://en.wikipedia.org/wiki/Tachyon) are a hypothetical particle that constantly move at speeds in excess of the speed of light. We haven't yet proven their existence, but neither have we disproved their existence (which is, as far as I know, impossible to do: one cannot prove a negative).
We have a clear ability to detect and identify creatures that are comprised of particles that move slower than the speed of light, so we know they exist. We are proof of that!
Let's suppose that tachyons do exist, but we simply lack the means at this point in time to detect them. Could it be possible that a creature made of particles that constantly move faster than the speed of light exist in our universe?
Were a high-energy creature to exist, how would it interact with the material universe we commonly perceive, if at all?
Lastly, if we were to finally detect high-energy particles and, following that, a creature made of them, how might we, as material creatures, experience communication with such a high-energy creature?
---
For your answer, you may refer to any creature made of faster-than-light particles as high-energy and any creature made of slower-than-light particles as material. I am interested in answers based in science, but I am not marking this as hard-science because I am aware that faster-than-light particles are purely theoretical according to our current understanding of physics.
I am not concerned with such a creature's development in this question, merely its possible existence and interactions with its environment.
[Answer]
People who invoke tachyons need to "keep reading": <http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/tachyons.html>
>
> The bottom line is that you can't use tachyons to send information faster than the speed of light from one place to another. Doing so would require creating a message encoded some way in a localized tachyon field, and sending it off at superluminal speed toward the intended receiver. But as we have seen you can't have it both ways: localized tachyon disturbances are subluminal and superluminal disturbances are nonlocal.
>
>
>
As for a creature made of such particles, how can you have solid objects or any kind of structure at all when the particles travel faster than light *relative to each other*? It's not like you can have them in formation traveling fast only from your point of view. Special Relativity still holds.
You can find lectures by Leonard Suskind on youtube, meaning anyone can effectively audit his classes at Stanford, for free. This includes full courses in quantum mechanics and introduction to string theory. In one class he covers what a negative mass-squared term *really* means (an inverted pendulum energy state) and how they end up propagating waves at normal light-speed anyway.
---
For your specific points,
* *structures* could not exist. The particles move faster than light relative to each other.
* they don't really travel faster than light, anyway.
* how would it interact? How indeed. Come back to that below. Communication is in the same boat with detection in the first place.
---
My only thought would be an [*energy being* trope⚠](http://allthetropes.wikia.com/wiki/Energy_Beings). A quantum field is the fundamental thing, and "particles" are quantized excitations in the field. There are also "virtual particles" and other non-particle excitations and disturbances. In a tachyonic field, the idea of particles gets weird, and being different from quantum fields we're used to you could handwave some effects that exist as patterns in the field with extended lifetimes that are not giving rise to conventional particles. Few hard SF readers would find it implausible, especially if you explained all that and used it to make an *energy being* more plausible than normal.
You still have to figure out how to get it to interact with normal matter and electromagnetism. That is a problem with *any* exotic matter that's not atoms and not electrically charged. You get "dark matter", and a dark matter monster could be here right now and not bother me in the slightest!
The tachyons analyzed in the linked treatment are Bosons. Let's suppose you have a fermion version and your creature is made from that. Fermions affect each other via bosons, which are associated with *forces* (or more generally, *interactions*). The exotic material needs to share a *charge* property with our kind of stuff. E.g. if it was electrically charged, it would interact with atoms via electromagnetic phenomena. It would also release Cherenkov radiation with exponentially increasing energy forever, so that's not good.
Real dark matter candidates and seriously considered un-discovered particles include [WIMPs](https://en.wikipedia.org/wiki/Weakly_interacting_massive_particles), which interact via the weak force. So plausibility leads you there as the path of least resistance.
There's always gravity. But detecting small objects via gravity would be difficult. Maybe anomalies in gravity measurements lead to the discovery, from other experiments involving measuring gravity over short distances. Maybe the WIMP clouds are attracted to our apparatus being used to probe for large extra dimensions or make a perfect reproducible kilogram standard, and these turn out to be not simple clouds but life.
] |
[Question]
[
This question builds on these previous questions:
* [What common structures and systems exist in global organized religions?](https://worldbuilding.stackexchange.com/questions/6597/what-common-structures-and-systems-exist-in-global-organized-religions)
* [How to explain the co-existence of peace and violence in religion](https://worldbuilding.stackexchange.com/questions/7301/how-to-explain-the-co-existence-of-peace-and-violence-in-religion)
I am attempting to create a monotheistic globally dominant religion. The religion will be:
* Expansionist, by both missionaries and the sword
* Centralized in a manner akin to Catholicism, though a decentralized (Orthodox Christianity or Islam) system is fine as well.
* Have both a hierarchical priesthood and a militant arm
* Able to motivate followers to violence against non-adherents
The question I have at this point is:
**Does a religion that meets these criteria need a 'prophet'? Mainly meaning the role that Jesus or Mohammed played in the evolution of Islam and Christianity.**
If it is not required does the presence of such a person make it easier, so to speak?
The answer I am looking for should have real world examples to support a yes or no answer.
[Answer]
In order to address the question, I need to make a few assumptions. If these are invalid, please correct me.
By "expansionist," I take it you mean that the socio-cultural complex defined as "God-ism" [to use a dippy empty title] has a tendency, expressed as an overt desire, to extend its reach across other populations. This is not at all obvious. If Godism is "expansionist" in this sense, it does not, as did Cyrus for instance, wish to conquer other people and allow them to practice their preexisting traditions under new rule (i.e., pay your taxes and bow down before the elite natives, and you can otherwise do as you please). Again, it's not that Godism happens to be expanding effectively because, coincidentally, the Godist Empire is conquering very well at the moment, but rather, Godists deliberately wish to expand Godism for its own sake.
On this basis, it strikes me that the obvious counter-example to the "must have a prophetic figure" thing would be the Aztecs and the Triple Alliance. Not monotheistic, to be sure, but otherwise they pretty well fit your list of criteria.
Now if you define "prophetic figure" to mean any inspired leader-figure of some ongoing historical significance, you're going to be hard-pressed to find any socio-cultural complex that doesn't have these. But if the sort of prophetic figure you're looking for is a singular central figure, a name that acts as a core banner under which the faithful march to war and so forth, there actually aren't all that many examples -- and arguably, most of them are counter-examples.
Consider early Judaism, which fits every one of your criteria very effectively... except that, with some occasional remarkable exceptions, this was not a missionizing-converting sort of complex. Expansionist in every other sense, but not by way of conversion (usually -- there are some interesting moments when people are forced to circumcise at sword's point, quite literally).
And then there are many periods and moments in Islamic, Roman Catholic, Protestant, and Orthodox history when expansionism was emphatically non-violent, to the point that it produced far more martyrs than converts. Does that count?
The problem with producing a lot of real-world examples is that monotheism isn't really all that common, and on the whole, it has apparently happened with prophetic figures of some sort. On the other hand, you'd be hard-pressed to demonstrate that any one figure in these traditions so absolutely dominates as to obscure all others. (I am reminded of the Shi'ite fascination with figures other than Muhammad, the utterly central role of St. Paul in most Christianities until quite recently, and the wide variety of Jewish central-prophet figures apart from Moses.)
I am aware that some have argued -- Karl Jaspers' "Axial Age" [*Achsenzeit*, if memory serves] proposal is the most famous, though not the first -- that centrally-dominant prophetic figures are an essential characteristic of expansionist, civilizing religions. But there are an awful lot of vehement counter-arguments as well.
In short, I see no reason whatever that you can't have the situation you've described without central prophetic figures if you don't want them.
[Answer]
The central feature of most religions is that all other religions are false or at least less correct. This means there must be some clear separation between the religion and its closest competitors that **proves** that it is **entirely different** from other religions. After that superiority is easily attained by the traditional method of shouting louder.
**Prophets** are necessary when the religion has a predecessor it wishes to be distinct from. The prophet himself usually only wishes to reform the previous religion and then gets promoted to a religion founder when political differences between their supporters and the old guard become permanent. But in case of Islam the breakdown of relations happened while the prophet was still alive.
Sometimes the breakdown never becomes final enough. Most Protestant faiths have a charismatic founder his followers idolize, but still consider themselves Christian and recognize both other Protestants and Catholics as fellow Christians. Islam and Buddhism also have several recognized forms. This is probably because these religions already have a highly respected founder figure believers do \*\*not\* want to replace.
There are other methods of separating the one true religion from the false superstitions of heretics. Some of them might work for your religion. Or not.
**Dogma** means in this context a permanent theological difference. While protestants consider themselves Christian, they do not consider themselves Catholic and in practice function as a separate religion. The same is true of Shiites and Sunnis. If the dogmatic difference is that the founder figure is no longer considered sacred, merely a very wise teacher among other teachers, the new religion might not have a prophet even if the previous one did.
**Nationalism** used to be central to religions. While the existence of other Gods and religions was recognized, you people would have a pact or connection with one particular God with particular rites and traditions. While such religions are originally limited to a single city or tribe and tolerant of what outsiders believe, there are numerous examples of the people becoming expansionist and intolerant, conquering their neighbours, replacing their temples with their own and forcing the conquered to change to the proper religion.
This historically has had unpleasant undertones of the Chosen People, who are superior to other people, which you probably wish to avoid. But there is the example of Judaism which went from an intolerant national religion to one of the most popular religions in the Roman Empire with universal appeal in a fairly short time. But this is probably explained by Judaism having both prophetic figures (Moses and Abraham) and strong dogma (the law) in addition to the nationalism. And a large empire might have an Imperial Cult it uses to unite its people regardless of ethnic origin into a single nation.
**Ancient** religions might simply be too old to have or need a founder figure. If the origin of your religion is lost in pre-history there is little need to make a big deal of how its founder separated it from its predecessor. Nobody cares any more. There probably still is some sort of origin story and it might even mention a specific person by name and people might have celebrations in his honour. But the founding celebration might instead be a pilgrimage to some sacred place where the religion originated. Or focus on a specific date when the God descended from the Heavens to reveal the truth.
I doubt this **answers** your question, but it should give some food for thought.
[Answer]
What you have to understand about religion is that it's about supernatural revelation, let me explain by contrasting science to religion:
Science is all about making observations in the past and then using them to 'predict' the future. It can never explain why something is the way it is, all it can do is say 'based on what we saw in the past the following is likely to happen'. Simply put, science has nothing to do with understanding, truth or meaning. Religion in contrast is able to make a claim on truth, but the way it makes this is by claiming some kind of 'contact' with absolute knowledge. Thus, regardless whether the claims or truthful or not, religion is all about understanding, truth and meaning.
Now, the way normally this claim is put forward is that there is a single individual who has 'received' such supernatural (as in, outside of the natural world, **not** as in: ghosts, spirits etc.) contact/revelation/whatever. You seem however to totally misunderstand that this is always by a single figure. In a religion like the Islam or Buddhism this is somewhat true, however in religions like Christianity and Judaism there have been very many prophets. Take for example Christianity in the early days, it was 'started' through the revelation of Jesus, however individuals like Peter had a very prophet-like role as well and on top of that you had thousands others who by definition could be called prophets as well.
So, to answer your question:
1. First decide whether the religion is real. Has there truly been a case of supernatural revelation, or is this something started by just humans.
2. If started by just humans a single central prophet figure makes sense, as he will be the only one putting forward the claim on having a supernatural message and others will not be able to 'check' whether it's real. And yes, you could also have a group that puts forwards their stories as a coordinated effort to start some religion, though in this case do note that you're somewhat limited in time (setting up such effort over the course of hundreds of years would be... hard to say the least).
3. If within your world the religion is 'real' then you do not need a central prophet figure. Every individual can somehow see some of this supernatural revelation. As you however wish for a hierarchy some will need to be 'better' at this than others, but you can just as easily have a circle of guys in the middle as you can have a single individual. A real God isn't limited to communicating to just a single person. He can choose to, but it's not a requirement and he could just as easily give hundreds of people little instructions to create the kind of religion you wish to use for your story.
PS. Just to discuss polytheistic religions, in those cases they can be fake without a central figure for the following reason:
However their knowledge claims (as in, 'amount' of supernatural knowledge) will be relatively weak.
[Answer]
Establishing any religion on marketplace of ideas **requires a a prophet** /master salesman, selling this ideas and **promoting it over competing ideas** (of which are plenty).
BTW "market of ideas" is not demeaning. It just means that **ideas need to compete with other ideas in minds of audience.** Ideas able to win most of the mindshare win "the market". So promoting the idea means it needs to satisfy some needs of the audience, and prophet needs to understand the audience. It is not easy, and having divine help is obvious bonus.
Is there an example of an religious idea flourishing **without** a prophet figure? I am not aware of any, but I am eager to improve on my ignorance.
[Answer]
I would say that a single prophet is not needed, with a few caveats.
1) Some prophets are needed. Religions are not rationale, so you cannot reason people to accept them. You need some people to claim supernatural inspiration.
2) From 1) and your question, it follows that you need a corpus of prophets. This brings another issue: discrepancy. If they are of the same religion, most of what they say will match, but the differences will be crucial (look at Christianity if you want some examples). You need some mechanisms to balance that:
* For example, censoring the prophets'teachings so newer generations only get access to the prophecies accepted by the "church". Maybe your prophet Ronald preached that people should donate their riches to the church, and that priests should be castrated. Most probably, newer generations will only hear about the first part.
* Another method is denouncing those prophets who are more openly against the church as heretics or demonic agents, but that approach is less subtle and more open to provoke conflict, specially if supported by terrenal powers$^1$.
In all situations, it is important for the church to keep control of the culture (even to the point that only priests know to read) and the access to the divinity (the priest is the mediator between the people and the god$^2$).
I think a model could be Jewish religion, which draws from prophets, patriarchs and other books and which shows the evolution of the religion (from Babylonian legends to adoration of a single mountain, to its final forms).
Of course, Jewish religion is not proselitist, but that is because it is old and, as such, is henoteisc$^3$: you cannot justifiy that the hebrews are "the chosen people" and special because of their origins, and then explain that they should try to convert all of the world to their faith (if all the people become "chosen people", what is the fun in it?). Apart from that origin, you could use the same structure of the Old Testament/Torah to found a proselitist religion.
$^1$ Heresies similar to Luther's had begun during the Middle Ages, but got no political support and were quickly crushed. Now, Luther came at an age when many princes got more political control and wanted to become free from Papal pressure.
$^2$ In a sense, the priest becomes the god. The more complicated and obscure the ritual to access to the god, the more important the priest will become.
$^3$ That is, every nation, tribe etc. has its own god/s that protect them against other nations, tribes and their gods.
[Answer]
**A prophet is not needed, but is convenient. What is needed is something to keep the message coherent.**
Your expansionist religion is willing to push against the world to convert people, rather than waiting for the world to come to it (which would be more Buddhist). When it does so, it will encounter opposition. If the opposition detects a message that is not coherent (i.e. there is not one message, but a fractured body of competing messages), the opposition will play this to counter your religion. The harder you want to push, the more important this will be.
The easiest way to do this is to have a definitive source of "truth." A prophet is very effective for this. However, it doesn't need to be a person. A tightly knit priesthood could control a message well enough to create this coherent message without a prophet.
[Answer]
An expansionist religion almost certainly needs a single, compelling **message** to deliver unto the heathen and convert them. It seems human nature that whoever comes up with this message, be it one man or a even a small committee, would then be imbued with the aura of a prophet or the equivalent. For example, the US "Founding Fathers" have a certain degree of that aura even though the creation is secular.
I can only see it not being so if the document produced is something like the volumes that bureaucrats turn out these days...huge volumes nobody reads. And then nobody would adopt them and the religion would fade.
] |
[Question]
[
In the book i'm currently working on, the main protagonist has a special (yet unknown himself) mutation because his ancestors have been involved in nuclear disasters while their mother was pregnant. more precisely: his grandmother was conceived a few months before Chernobyl, in Pripyat. After the Soviet Union dissolved, she managed to escape to Fukushima, and was pregnant with the protagonist's mother during the incident there. The mother then moved then moved to Belgium, and was in Antwerp during a terrorist attack on Doel around 2034, when she was pregnant with the protagonist.
He ends up on a kinda futuristic version of Earth, with Belgium being the global powerhouse. Most of this was caused due to the inhabitants of Belgium having had similar radiation back around 100 BC or something like that, basically when they were being invaded by the Roman Empire. The effect of the radiation has faded for about 500 years now, and the radiation itself hasn't been around for over 2000 years. However, the muttaion, combined with a certain chemical in the atmosphere, gives above-average attributes to the person infected with it, explaining why Belgium managed to conquer most of the world.
the problem is that I need to find a way to expose a 30,000 km² area to a constant yet low amount of radiation, that only lasts about 50-70 years (enough for 3 generations to be born), in a way that appears coincidental to casual observers, almost a freak of nature. The idea is that they won't have a method to even know that there was radiation for a while, long enough to make most signs of the radiation disappear, even in the affected people.
>
> The real reason for the radiation is that it's been placed there by a precursor race that has their own goals for humanity, so a solution that can feasibly be done by such a race is preferable.
>
>
>
Basically, what I want to do is expose Roman-Era Belgium to a small amount of radiation for a short timespan, with no way for the Belgae to notice this for at least 1500 years. The method should be doable by an outside force thousands of years in advance.
[Answer]
So you want to expose a small area to significant levels of nuclear radiation over a period of time using natural means?
My suggestion would be to use a mix of the following three things:
* [Radon gas](http://en.wikipedia.org/wiki/Radon) - emitted naturally from some rocks, radioactive.
* [Natural nuclear reactor](http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor)
* Mining
So you have a natural underground nuclear reactor and in general a large seam of material with a high uranium content. Mining then exposes the miners to high levels of radiation, but the process brings to the surface large amounts of uranium ore and releases large amounts of Radon.
Widespread mining means that this effect covers a large area and effects everyone living there. Essentially the major industry of the area is mining and as a result the entire population gets exposed.
[Answer]
This sounds a lot like [How do I drug a population in the most efficient way?](https://worldbuilding.stackexchange.com/q/843/2428).
The main problem I see is that radiation just doesn't work that way. To my best knowledge, you cannot create a "special kind" of radiation that will cause particular mutations. You can limit the effect to certain cells by only irradiating those, but most mutations will still not be very effective. Decreasing the power won't make it any more effective; it'll just make both harmful and non-harmful mutations less common.
Disregarding that, my suggestion would be to put it in the water. It's the easiest place to rapidly start adding a substance to, either by adding something to the wells or modifying the rain (if you have the technology). In a case like this, you can get the radiation to become fairly insignificant by the time humans can measure it by choosing an isotope with a [suitable half-life](http://en.wikipedia.org/wiki/List_of_radioactive_isotopes_by_half-life#109_seconds). Water with [Tritium](http://en.wikipedia.org/wiki/Tritium), refreshed every five or so years, could work wonders on your population.
Alternatively, you could make a whole in the ozone layer. That would increase radiation, and people at that time would likely notice little else than "being in the sun makes you sick". I am not sure what would have to be done to recover it later.
For the "thousands years in advance" part, you're going to have some logistic issues. Robots that manufacture and distribute whatever it is you need and then self-destruct are probably the best option.
As an alternative that takes that into account, they could have launched a spaceship containing a radioactive compounds at speeds near that of light. If it were to keep going at that speed and crash back into the Earth, far less time will have passed for it than for the planet, which would mean that rapidly-decaying particles wouldn't have decayed yet. This could then be written off by the Romans as a meteorite impact.
[Answer]
How important is it to you that the mutations arise by radiation? There are many other means for a precursor race to edit the genome of a population without relying on generating random mutations.
A retrovirus, properly engineered, would be capable of infecting a limited population and inducing any changes to their genomes that could be desired. That could include introducing the desired mutation itself, or weakening the DNA repair machinery to cause the infected people and their ancestors to have an increased rate of mutation even in the absence of radiation or another mutagen.
Otherwise I think your best bet is a giant X-ray/gamma-ray/UV laser on the moon or in orbit. It could simply fire radiation down onto your desired area. Most would be absorbed by the atmosphere, but a large enough laser should be able to increase the mutation rate. This is similar to the hole in the ozone, but a bit more straightforward I think, because you don't have to go back and fix it the ozone after, you can just fly your laser away or self-destruct it.
[Answer]
I like both of Anton's ideas (ozone hole and water supply), but here's an additional possibility: meteorite impact.
If a meteorite contains enough radioactive material with the proper half-life (whatever that may be), it could -- theoretically -- be set on an Earth intercept course by an advanced race quite some time before it's impact time. The race doing this may not be able to predict with precision exactly when or where the asteroid will strike (due to accumulation of small, persistent effects like solar radiation pressure, minor gravitational perturbations, etc... which, over the course of thousands of years, will affect the orbit) but it should know that it will strike eventually. This meteorite could explode in the atmosphere, spreading radioactive dust through the atmosphere and across the soil, or it could provide a much smaller (but more concentrated) debris cloud upon impact. This could even be what contaminates the water supply in Anton's scenario. OTOH, statistically speaking, an asteroid is most likely to land in the ocean.
Eventually, the material it contains will decay to a stable isotope. However, the trick here is the whole "set it up thousands of years in advance" coupled with the required short (decades or centuries) decay time. If the half-life is short enough that it mostly disappears over that short of a time span, you would need a very large amount of it to begin with, to ensure that it doesn't entirely disappear before impact. As an example, let's say your chosen material has a half-life of 50 years. So if the impact introduces quantity Q of this material into the environment, then after 50 years, you will only have Q/2 of this material remaining. But 1000 years before the impact, you would need to *double* this amount for each half life: that's 1000/50 = 20 doublings. So you would need to start with (2^20)\*Q = 1,048,576\*Q -- over a million times! In other words, if you started out with the entire meteorite being radioactive, less than a millionth of its mass would be radioactive upon impact. Of course, you can choose a longer half-life material, but then it might take longer to clear out of the environment...
Unless it doesn't. It's possible that with environmental effects -- wind, rain, erosion, etc --- the contaminated material might be dispersed into a wider environment (e.g. running off into the ocean), causing it to become less concentrated and therefore less dangerous. This would allow you to use a much longer-lifed isotope (and thus set things in motion long before hand), but without knowing where the meteorite would land, it would be difficult to predict how long this flushing effect might take.
] |
[Question]
[
Can life exist on planets as barren as Mercury? How would it survive? It seems like it couldn't. Mercury is very hot, would any life break down becuase of the heat? What other challenges face life on Mercury?
[Answer]
Anything is possible
---
Life as we know it on Earth could not exist on Mercury without serious terraforming. Mercury has very large temperature swings, the side facing the sun can reach temperatures of around 900 C, while the dark side can drop to temperatures similar to that of deep space. Because of this, liquid water cannot exist on Mercury, and water is a hard requirement of life on Earth.
Mercury also faces frequent asteroid impacts. Because Mercury lacks an atmosphere, these impacts would be unimpeded and highly dangerous. All life would likely be destroyed by them. I would like to note that Mercury does not face bad impacts from solar wind, because it has a strong magnetic field, slightly stronger than Earth's.
---
The question does ask how life could exist, and my favorite phrase on this site (see top of post) definitely applies. Life as we know it could not exist on Mercury, at least not without impressive terraforming (see next section). But life on Mercury could exist if it didn't rely on water, and could stand rapid and violent heat swings. Or if life could survive in the magma of a planet, then it could live on Mercury. In an Earth based context, these don't make sense, but using soft-science it would be possible.
---
Another possibility would be to terraform Mercury. The first step in terraforming any atmosphereless planet is to give it an atmosphere. On Mercury an atmosphere would be difficult to maintain because it has such small mass, about have the size of Mars or 0.55 Earths. Gravity enhancers may be necessary to maintain an atmosphere, this has not been tested so we can't know fully. A magnetic field is not a problem, Mercury already has one.
After adding an atmosphere, the next step would be to stabilize the temperature. This would require moving energy from the warm side of the planet to the cold side. Once an atmosphere is in place, it is not necessary to move as much energy as some energy will be kept. Once the temperature is around the planet, most of the energy should be reflected. Then water needs to be introduced along with terrestrial life.
It is possible that underground habitats would be easier to manage, but they would still require significant ability to manage heat. An atmosphere, at least in the habitable space, would also be needed.
---
References
<http://www.universetoday.com/22097/life-on-mercury/>
<https://en.wikipedia.org/wiki/Mercury_(planet)>
<https://en.wikipedia.org/wiki/Terraforming#Other_bodies_in_the_Solar_System>
[Answer]
It would not be possible for Earth-like life to exist there. Perhaps some kind of metallic-based organism, or something similar to a biological nanobot (an advanced type of virus, maybe?) with extreme self-repair capabilities, extreme resistance to heat and radiation, might be able to survive, especially in areas like the sides of ancient craters, where the sun never fully reaches but which aren't in complete darkness either, and which are less likely to be affected as much by new bombardment.
[Answer]
Mercury is not as hot all over as it looks. [There is water ice on its surface that may well be permanent](http://www.space.com/27450-messenger-mercury-water-ice-photos.html). Granted, that's not necessarily permanent on the timescale required for life to develop.
However, like the Moon, the reason that there's water ice in shaded areas is because there's no significant atmosphere to actively transfer heat. And no atmosphere means no pressure, which means no liquid water (it sublimes from solid to vapour). We don't really have the first clue what something might look like that exists in the absence of both liquids and gases, but that we'd choose to call "life" once we saw it.
So things aren't looking good for native life on Mercury, but it's not quite so simple as "too hot".
If you're talking non-native life, then building some kind of station in a shady spot on Mercury isn't absurd. Underground would probably make more sense, though. But that's just a special case of, "with enough technology you can build a climate-controlled habitat almost anywhere".
[Answer]
>
> It is known that there are an infinite number of worlds, simply
> because there is an infinite amount of space for them to be in.
> However, not every one of them is inhabited. Therefore, there must be
> a finite number of inhabited worlds. Any finite number divided by
> infinity is as near to nothing as makes no odds, so the average
> population of all the planets in the Universe can be said to be zero.
> From this it follows that the population of the whole Universe is also
> zero, and that any people you may meet from time to time are merely
> the products of a deranged imagination
>
>
>
Life is a strange and varied thing... And I guess "Life as we know it..." is a somewhat relative term. New species are still being discovered on a fairly regular basis.
I would guess that if we one day discovered life on a planet like Mercury it most likely take the form of an [extremophile](http://en.wikipedia.org/wiki/Extremophile), most likely some sort of [hyperthermophile](http://en.wikipedia.org/wiki/Hyperthermophile).
The hypothesis of [panspermia](http://en.wikipedia.org/wiki/Panspermia) would seem to suggest that finding these tiny survivors on inhospitable planets would be entirely possible.
>
> Panspermia is a hypothesis proposing that microscopic life forms that
> can survive the effects of space, such as extremophiles, become
> trapped in debris that is ejected into space after collisions between
> planets and small Solar System bodies that harbor life. Some organisms
> may travel dormant for an extended amount of time before colliding
> randomly with other planets or intermingling with protoplanetary
> disks. If met with ideal conditions on a new planet's surfaces, the
> organisms become active and the process of evolution begins.
>
>
>
[Answer]
I disagree on the impossibility of life. There are areas on Mercury that experience a milder climate (other than the lack of an atmosphere) than the Earth itself. I have even seen a proposal to colonize them.
The closer you get to the poles the cooler it gets, there's a ring around each pole that averages what we consider comfortable and once you go deep enough underground it stays this way all the time.
While it's not likely that live managed to evolve in such an environment we can't rule it out.
[Answer]
Imagine Mercury with more water. This would create an atmosphere of water vapor. If there was a lot of water the planet would get a thick water atmosphere and have a runaway greenhouse and turn into a steamball (see here: <https://planetplanet.net/2016/04/06/no-livable-planets-without-life/>). With a modest amount, water would likely simply be transported to cold traps and freeze out, like in craters or at the poles or on the night side of the planet. Since the planet is in 3:2 spin-orbit resonance, its day is about 59 days (its orbit is 88 days).
I can imagine a really interesting setup. There are 3 source of water on a wetter (but not too wet) Mercury: 1) randomly-located ice deposits in large craters; 2) permanent cold traps at the poles; and 3) a cold trap on the night side that migrates across the planet as the planet rotates. I'm not sure whether this migrating cold trap would persist but it's an interesting idea. It would be sort of like an Eyeball planet (see <https://planetplanet.net/2014/10/07/real-life-sci-fi-world-2-the-hot-eyeball-planet/>) but one that is constantly changing as the planet slowly spins.
Life on such a planet? Well, where there is water on Earth there is life. So, I think it's totally plausible to imagine life in two places: at ice deposits (permanent or migrating/temporary) and in the subsurface, also in water-rich areas.
] |
[Question]
[
**Context / technology level:**
* I have a more-or-less Age of Sail airship. It is not intended to be entirely self-sufficient, but it should be able to make long trips with small stops to restock/repair; analogous to a naval sailship.
* There is magic which allows it to overcome the problem of an airship being unable to move relative to the wind.
* The same magic also enables the sailing airship to reasonably control its altitude without routinely jettisoning ballast or lifting gas.
* There is a fantastical material available to use for the gasbags; greatly reducing passive leakage and allowing one fill of lifting gas to last a long time.
* The magic and the fantastical material do **not** make the ship itself sturdier against weather or other causes of damage.
**Motivation for the question:**
Given the technological context, it seems to me that the limiting factor for such a vessel's range between stops would be drinking water. The range could therefore be (significantly?) extended if the ship were able to collect water from rain or clouds while in-flight. It is mentioned in passing on Wikipedia that collecting rainwater in an airship is/was done as a redundant buoyancy compensation system. While I haven't (yet) been able to find detailed information about the setup of the system, it's enough for now to take it for granted that it's possible.
However, it seems to be common knowledge that airships are highly vulnerable to bad weather (expressed clearly in [this answer](https://worldbuilding.stackexchange.com/a/194630/51300)), and just steering for the nearest cloud to harvest rain from it might [not always be a good idea](https://en.wikipedia.org/wiki/Helgoland_Island_air_disaster).
Given that my Age-of-Sail airship will not have weather information updates by radio, and will be relying primarily on visual observation and instruments that give temperature, air pressure and altitude, **how can it best determine which weather formations are safe for water collection?**
In your answer, please specify, to the best of your ability:
* Types of weather formations that ought to be avoided, and why they are a threat (what might go wrong if we entered them?).
* Types of weather formations that ought to be useful for rain collection, and why you are convinced they are safe.
* Enough context or scientific terminology that I will be able to research your indicated weather formations to identify where and when one can expect them to form.
[Answer]
Avoid thunderstorms due to the strong vertical shear.
Avoid cold/warm frontal boundaries due to the strong vertical and horizontal shear.
Look for low (not too low), scattered cumulus clouds. Focus on darker clouds that already emit rain or virga (rain that doesn't reached the ground), generally in the afternoon. Those are your safest target. Avoid cumulus congestus clouds -- while they are more reliable rain producers, they are also more reliable wind shear producers.
The Graf Zeppelin harvested rainwater occasionally using a system of gutters. The water went to ballast, not drinking. Ballast was needed because daytime would heat the lifting gas, causing the ship to ascend (solution: Valve a bit of gas). But then at night the gas would cool, causing the ship to descend (solution: Drop some ballast). The ship did NOT depend upon this method for replenishing ballast regularly -- it was an occasional opportunity.
The specific method the Graf Zeppelin used was to brush one side of the ship against the rainy part of the cloud. This permitted them to control the amount of water collected, and prevented the ship from becoming too heavy (that would be bad). They did NOT dive through the cloud. That was considered much too risky by experienced airship officers. (Those guys weren't wimps -- many had previously demonstrated their courage night-fighting repeatedly over the skies of Britain during World War I, and many were fiery-crash survivors. To them, clouds weren't fluffy and pretty. Clouds meant the troposphere was trying to kill them.)
[Answer]
High above the raincloud. You need a wide funnel, a barrel, strong rope, and a sturdy winch.
A steel cable might seem better than rope, but there is going to be some possibility of drawing lightning using it. Silk rope is strong, so would probably be a good choice.
Best case: A barrel full of fresh clean rainwater.
Worst case: Something goes terribly wrong: Ship destroyed, crew dead, casualties on the ground, demands for reparations, diplomatic missteps, declarations of war, allies called in, a world war.
Let me know how it turns out. üòÅ
[Answer]
Framing challenge. Your aim is to get drinking water, not to "collect it from clouds"
Solutions
1. You're running it through your engines. Assuming your engines run on Hydrogen, burning your fuel produces pure water. If they run on Petroleum, it produces water and carbon dioxide. How much? [This answer](https://www.quora.com/How-much-water-is-formed-by-the-combustion-of-1-litre-of-petrol) runs though some math and arrives at 1L of fuel combusts to produce approximately 1L of water. Sounds off, but most of the mass of H20 is in the oxygen atom and thus comes from the air. Thus if you stuck a reclamation system on your engine exhaust, you would continually be producing a small steady supply of it. Airships are not fuel efficient. [This answer](https://worldbuilding.stackexchange.com/questions/13514/how-fuel-efficient-are-airships) suggests a rating of 0.25 km/kg, or about 1L of water would be produced for every 5km traveled. The Graff Zepplin cruised at ~100km/hr, so you're producing 25L of water every hour, or 600L per day. As far as I can tell, the Graff Zepplin once carried a peak of 38 passengers, so they have about 15L each per day. This equates to a 1.5 minute shower (a shower uses about 10L/min), but if they shower every second day it's probably enough for drinking/cooking as well.
Of course, if you are purely sailing, then this option doesn't work.
2. Dehumidifiers. Rain falls when there is so much water in the air that it does not stay in gasseous state and instead condenses. There is a way to force this. Have you ever taken a can of coke out of the fridge and left it on the counter? The outside quickly becomes wet. This is the principle of a dehumidifier. There is plenty of water in the air - it's just a case of extracting it. Cobbling together a refrigeration system in the age of sail is no small feat, but if your magi-neers are successfully steampunking it, they can probably cobble something together out of brass tubing!
3. Buckets and Lakes. See a lake below you? Lower a bucket. I seem to recall reading a story about a sailing ship doing this while at sea - they were by the outflow of some big river (Nile? Amazon?) so they were sailing in fresh water.
] |
[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/214762/edit).
Closed 2 years ago.
[Improve this question](/posts/214762/edit)
I'm contemplating writing a fiction set in modern China in an alternate universe. I have thought about how it would look like, but I need a plausible alternate history that could lead to such result.
**Setting**
It was the year 2020 AD. China was a federal constitutional monarchy in the alternate universe. Unlike most federations in our universe, its different federal units had vastly different nature, ranging from kingdoms to special administrative regions. In total, it consisted of *3 kingdoms, 2 khanates, 2 republics, 4 special administrative regions and 1 capital district*.
**Kingdoms**
The three kingdoms were located in North China Plain, Yangtze Plain and Sichuan Plain respectively. Among them the kingdom in North China Plain was the most politically powerful. They together made up more than 60% of population. Their heads of federal unit were called *Kings/Queens* and were hereditary positions. The royal family of the kingdom in North China Plain had a mixed origin of Han and non-Han, while the other two royal families were Han for the most part.
**Khanates**
The two khanates were located in Mongolian-Manchurian steppe and Tarim Basin respectively. Their heads of federal unit were called *Khans* and were hereditary positions. Both khan families had a mixed origin of Han and non-Han.
**Republics**
The two republics were both located in southern China. Their heads of federal unit were called *Chief Ministers*, who were also their heads of government and were elected positions.
**Special administrative regions**
Among the four special administrative regions, two of them were located in Pearl River Delta and other two in Yangtze River delta. Their heads of federal unit were called *Chief Executives*, who were also their heads of government and were elected positions.
**Capital district**
The capital district was the oldest and the central part of Beijing. It was also called the *Old Beijing* by the locals. Its head of federal unit was called the *Mayor*, who was also its heads of government and was elected positions.
**Emperor/Empress of China**
The head of state on federal level was called the *Emperor/Empress of China*. **Whoever succeeded to the throne of the kingdom in North China Plain was automatically crowned the Emperor/Empress of China.** However, in case the kingdom in North China Plain was in regency, the Kings/Queens of the other two kingdoms could act as regents for the Emperor/Empress of China.
Being the monarch in a constitutional monarchy, the Emperor/Empress was largely a ceremonial role and had limited political power. Their most significant power was to appoint the *Prime Minister*, who was the head of government on federal level.
**Republic of Formosa**
A.K.A Taiwan. The Republic of Formosa was not under the sovereignty of China, but it recognized the Emperor/Empress of China as its head of state. This was similar to how Canada and Australia recognize the UK monarch as their head of state in our universe.
**Question:**
What plausible alternate history would lead to the China described above?
[Answer]
I might have a partial vision of history, but I have the impression that the concept of constitutional monarchy has arisen originally in countries which had somehow contacts with the Greek concept of democracy, basically Europe, and even there for a long time it has been only England to have some sort of limitations on what the ruler could do with its Magna Charta, before it became a sort of widespread achievement. Between that England and the Greek civilization there is a large gap of fight between monarchs and their subordinates on who should hold the power.
Based on this I think you should have prolonged contacts between the Greek poleis and China, so that Greek culture can somehow permanently influence the Chines one, and after that China should follow a path similar to Germany to become a federation of smaller and bigger states under the ruling of a single monarch.
Probably the only way to achieve this is to have first an established trade relationship between China and Greece, followed by Alexander the Great successfully invading the North of India until reaching what is today China and keeping his power in place for a decent time through a durable empire, so that the states sprouting after the end of the empire he founded would embed part of the Greek cultural heritage.
[Answer]
**It was attempted for a few years.. it failed**
First some documentation/context
Once, between 1908 and 1911 they tried it. The Qing dynasty attempted to hold on to power, by doing concessions: introducing a constitutional system and put other reforms, to please the revolutionaries. China might have become a constitutional monarchy, with the last emperor and his political elite in power. Intentions were clear.. but the Qing never succeeded in actually founding a constitutional monarchy. This was - among other things - because the Qing-dynasty was Manchurian and not Han, which is the majority of the population. The 1908 proposal was not acceptable to revolutionaries, nor for the Han.. nor for the Qing elite..
The Chinese Republic was founded in 1912 and briefly overthrown a few years later, in 1915-1916 by Yuan Shikai, the architect of the Qing reforms. A war broke out and Shikai lost. And the child emperor Puyi now became emperor-in-name only, isolated in the Forbidden City.
Puyi would become the *very* last emperor of China. When China was invaded by Japan in WW-II, Puyi collaborated with Japan. After the war, he was put to prison for 10 years.
<https://en.wikipedia.org/wiki/Principles_of_the_Constitution_(1908)>
<https://en.wikipedia.org/wiki/Yuan_Shikai>
<https://en.wikipedia.org/wiki/Puyi>
<https://en.wikipedia.org/wiki/1911_Revolution>
As for the opening question, I see two roads rooted in history,
**Chinese constitutional monarchy from within**
You could say the Qing lost already with the Boxer uprisings in 1895.. or in 1912, or in 1916. Or definitely, in 1946. What would have been needed to change the above events ? In 1915-1916, the Qing attempted one more time to regain power, lead by Yuan Shikai, who inspired the reforms.
*Suppose* Yuan Shikai would have won the war in 1916 and prevent the communist and nationalist warlords from taking over ? Maybe he could have restored order and proceeded the constitutional reforms, with himself as emperor.
.. or *suppose* the 1908 reform would have been accepted in the first place, and revolution was avoided.. the successor Puyi was 2 years old, enough time to park the imperial elite and experiment with a constitutional monarchy, with the emperor getting used to ceremonial functions at a very young age.
**Chinese constitutional monarchy instated from the outside**
*Suppose* Britain would have imposed colonial rule over larger parts of China, in that case, decolonization negotiations could have resulted in an Anglo-Saxon model of constitutional rule, at least within these former British territories.
..or *suppose*, Puyi would not have committed treason during WW-II ? What if the Americans would had intervened, to help nationalist Chiang Kai-shek and prevent communist regime ? A constitutional monarch Puyi, head of state *in name*.. and a puppet as prime minister..
..or *suppose* Japan would have won WO-II.. same procedure as the Americans, they could have installed their constitution (which was the plan in 1908 anyway) and their man Puyi as constitutional emperor of China.
**Federal**
In the above scenarios, I avoided "Federal". Until far in the 20th century, China was divided. The strong central government in China pacified that situation for centuries. When the empire was compromised, war broke out. Then, the communists restored one China again, with central rule. A federation assumes relative independence of participants, which would result in separatism everywhere, like it played out in Yugoslavia, after Tito died in 1980. It was not viable as a single state.
[Answer]
There are two possible alternatives that could have radically changed modern China. Go back to the Mongol invasion and change that.
1. If the Khans had not conquered the different kingdoms in China. That would have left a far different political landscape, one that was fragmented and could have fragmented further.
2. If the Khans had decided to go with a "scorched earth" policy returning the conquered lands into pastures for horses. A greatly reduced population would have resulted which would not have supported a unified empire.
[Answer]
**Douglas MacArthur’s Success**
From Wikipedia:
>
> When North Korea invaded South Korea in June 1950, starting the Korean War, MacArthur was designated commander of the
> United Nations forces defending South Korea. He conceived and executed the amphibious assault at Inchon on 15 September
> 1950, for which he was hailed as a military genius.
>
>
>
At this point, reality turned on fate:
>
> However, when he followed up his victory with a full-scale invasion of North Korea on Truman's orders, China intervened in the
> war and inflicted a series of defeats, compelling him to withdraw from North Korea. By April 1951, the military situation had
> stabilized, but MacArthur continued to publicly criticize his superiors and attempt to escalate the conflict, leading Truman to relieve MacArthur of his commands.
>
>
>
Instead of MacArthur losing, or insubordination, or something, MacArthur managed to press on into China, expanding the Korean War into the US-China War for which the US emerged victorious.
One of the concessions was that China adopt a federal constitutionally based society, which the victors assisted China in adopting. The eventual form became a monarchy, primarily from the Chinese own participation.
] |
[Question]
[
*Notice : If you wish to know how to make an oscillating orbit with real-world physics, you can looky-look at this [question which is following mine](https://worldbuilding.stackexchange.com/questions/205099/oscillating-orbit-how-to-produce-one-in-the-real-world). My question focuses on the consequences of such orbit.*
## A wavy stellar system
I have a stellar system with quite unique properties. How this system has come to be is unknown, but its central body -which for sweetness we'll call a white-hole- has unique physical properties. It gives out a force similar to gravity but acting as the reverse of it with a "higher derivative strength" : By this mathematical word abomination, I mean it decreases faster over distance than gravity does. In other words, if you're close, you get pushed away, and if you're far, you get pulled in. As a consequence, there is a sphere/circle where you are in a state of weightlessness, where the gravity's force counteract the repulsing one. Later on, we'll call this line the neutral-line.
Around this white-hole stands a telluric planet, quite similar to Mars in terms of composition and orbital characteristics, excepted for one thing. Due to some yet-to-understand space history, its orbit is crossing 8 times the neutral-line, as it is oscillating from and to the pull-zone with contrary forces. It forms a pretty star-like shape, as you can see in the toy model I made1 below :
[](https://i.stack.imgur.com/ITVJX.gif)
*The red planet's orbit forming a star-like shape around the white star-like body.*
## My issue
This model, however, doesn't help me solve the fact that planets have got lots of added complexity, notably regarding their structure. They're not "solid as rock" like pétanque balls (or bowling ones if you're more accoustumed to them).
**So what can I expect the structure of such planet to be, relatively to Mars? Here, I ask :**
* Its general shape? An oval, a pancake (yummy!), exactly like Mars, something else?
* Would there be visible structure changes over-time at its surface when seen from another planet? Like signs of very strong pressures which leads to cracks, volcanic and seismic activity?
* And as part of a reality-check, would it be structurally obliterated into dust by such oscillations?
## Known data from the model
Here are some data I gathered from my model that I guess could be useful in understanding the thing. Although... Recall that it's a toy model with much, much smaller-scale data (we're talking in km, not AUs)! Therefore, I can only reasonably give relative differences, and there might be large scale differences I'm not aware of!
* **The speed of the object changes overtime**. In my model, it ranges from 1 unit to 2 units of speed, quite a lot if I dare say. As you can see on the image, the speed increases as the object gets nearer the white-hole, and slower as it gets further.
* **The force varies over time, too**. For 1 N of overall pull force I get at the furthest distance, I get 1.6 N of push back force at the closest one.
* **As for the distance, the planet's distance to the white-hole ranges from ~80 to ~140% of the neutral line distance**. We'll consider the neutral line distance white-hole to be the same of what Mars would have, so your orbit ranges from 80% to 140% of Mars's orbit.
* **For time, well... My model's going over the board and making a loop takes less than 15 minutes, so :D...** We'll take in that to make a full period, it's the same as Mars. The thing here is that because it's oscillating along the neutral line, I doubt the third Kepler's law to calculate orbital periods applies here. In fact, by adjusting the perpendicular initial velocity, you get different loop times, as you can see below :
[](https://i.stack.imgur.com/nbMsS.gif)
*A side-by-side race between two planets with different initial velocity. The yellow planet has half the initial perpendicular speed of the red one, and takes a lot more time to move around*
## Other data
Outside the model's results, know that the white-hole, apart from its physic changing properties, act like the Sun gravity-wise and energy emission-wise. If by chance you're missing something, consider it to be Mars or Sun-based approprilate... Appropriately.
## Therefore, what would be the structural impact a planet would face by having an oscillating orbit?
---
1 : *Here's the model formula, whose result is positive when the object is attracted towards the white hole, and repulsed when negative. I mainly used as a sketch-up, but if you need it :) :*
$$ F = -A \frac{m\_h m\_o}{d\_{ho}^{2.5}}
+ G \frac{m\_h m\_o}{d\_{ho}^2} $$
*With F being the force applied, mh the hole's mass, and mo the mass of the repulsattracted object, dho the distance between the hole and the object, G the [gravitational constant](https://en.wikipedia.org/wiki/Gravitational_constant) and A another "convenient" constant to balance things out. I don't really care what's inside the white-hole and didn't want to make general relativity calculations, so dho=0's undetermined result is irrelevant. Same for the white-hole's own movement, which I waived away since it's not really significant.*
[Answer]
## It's not the sun you should fear, it's everything else around it
In isolation, your planet would be virtually identical to Mars, assuming it was allowed to form and cool in the first place. In fact, since you're near the bottom of the gravitational potential well, the tidal forces would likely be much weaker than they are on Mars, so it could very well be slightly rounder and less "mixed".
You may be forgetting that circular orbits are still possible (and energetically favourable) - you can set centripetal force $$F = mR \left(\frac{2\pi}{T}\right)^2 = G m
\left[\frac{M}{R^2} - \frac{A}{R^{2.5}}\right]$$
where $m$ is the planet mass, $M$ is the white hole's regular mass, $A$ is the white hole's "antimass", $T$ is orbital period and $R$ is the equilibrium radius.
The main physical difference between this system and reality is that you have upset the standard relationship between angular momentum and orbital radius - there is now a unique, "magic" radius at which gravitational potential energy is minimised. Based on thermodynamics, I'd expect all of the system's garbage to end up there eventually, all in different oscillating orbits. The other remarkable thing is that any orbital period is possible at roughly the same radius - we actually don't have enough information to say what T is based on the number of wiggles. In fact, the other terrifying possibility is a stationary, stable orbit where the planet simply sits at $R\_0 = (A/M)^2$, where the gravitational force is zero.
This is a very different situation to our Sun, where every orbit is basically the same (just warmer/colder). Imagine your system was filled with a primordial soup of gas and rock - eventually, friction would compress this soup into a thin ring around the sun centered slightly beyond the neutral line. Within this ring, large planets would quickly form, potentially on some crazy wiggly trajectory. In such a scenario, collisions would be commonplace - your Mars would be riddled with craters, probably molten and possibly inside a gas giant. It depends how far you want the reality check to go, but the formation of such a system would be very odd.
[Answer]
The planet is just a planet.
It does not share the strange gravity of the star.
The star's forces on the planet are rather weak, the same as gravity. So they affect the planet's path as a whole, but have almost negligible effect on the planet itself. The full extent of local effects will be.... tides. Higher tides when the planet is closer to the star, lesser when it is further away. Both gravity and repulsion make the tides, all that matters is the balance, direction and gradient of the resultant forces. I do believe gravity tide will point towards the star, as our tides do, but repulsion tides will be 90 degrees radial to these. The result may be some interesting sloshing.
Just calculate the period of oscillation between closest and furthest for the planet. These are its seasons. Summer when the planet is closer to the star, winter when it is further.
The cycle around the star is interesting to astronomers, and not much more. It will not affect weather or climate or day-to-day life on the planet at all, just the scenic view of the stellar neighborhood.
[Answer]
## Summary:
If the planet has a "normal" day length and is strong enough to keep from flying apart under its own rotation, then it'll be a boring old oblate sphere.
### First-order effects on planetary shape: none
Assuming that the modified gravity law applies the same way to all constituent atoms of the planet, then your new force law obeys the [equivalence principle.](https://en.wikipedia.org/wiki/Equivalence_principle) In other words, since the planet is "freely falling" under this gravitational force, the physics in its neighborhood are entirely equivalent to those if the planet was isolated in deep space with no gravity at all. And if the planet was in deep space, then it would accrete into a roughly spherical shape under its own gravity, possibly with a small amount of oblateness due to its rotation.
### Second-order effects on planetary shape: varying tidal forces
Of course, there are small effects that the Sun has on the Earth's shape. The side of the Earth towards the Sun will feel a bit more gravitational force than the side of the Earth away from the Sun, since it is closer to the Sun and gravitational force decreases with distance. The difference between these force leads to the [tidal force](https://en.wikipedia.org/wiki/Tidal_acceleration), which is roughly
$$
F\_\text{tidal} \approx R \frac{d F\_\text{grav}}{d (d\_{ho})}
$$
where $R$ is the physical size of the planet. In your case, this will work out to be roughly
$$
F\_\text{tidal} \approx R \left[ 2.5 A \frac{m\_h m\_o}{d\_{ho}^{3.5}}
- 2 G \frac{m\_h m\_o}{d\_{ho}^3} \right]
$$
In principle, you could calculate how large these forces are. However, I would expect them to be relatively ineffectual so long as your planet is rotating. So long as your planet is rotating, then the stresses on the planet's crust due to its rotation will almost certainly be larger than the stresses due to the tidal forces. For a point of comparison, the tidal forces on Mars due to the Sun result in a relative acceleration of about $10^{-14} \text{ m/s}^2$; but the centripetal acceleration due to its rotation is about $10^{-2} \text{ m/s}^2$ along the equator. The calculations for your planet will, I expect, lead to similar results.
So long as the structure of your planet is strong enough to keep from flying apart due to its own rotation, and the planet stays far enough away from the hole, it should be able to handle the tidal effects. Even if they're time-varying due to the planet's varying distance from the hole, they are so incredibly small that they shouldn't threaten its structural integrity.
] |
[Question]
[
I'm not a chemist—I'm an artist and I occasionally write. But I'm starting to get more and more interested in xeno/speculative biology. When it comes to these things I'm pretty much just looking at stuff dumbfounded and trying to understand it. So every now and then I would like some advice from people who are much more galaxy brained than me.
My latest strange fixation is nucleic acids. I'm researching stuff for a personal sheet with alternative biochemistry things, and I sort of noticed that most backbone sugars I see being used are monosaccharides like threose, hexitol, altritol, and the naturally-occurring ribose and deoxyribose. So I've been kind of making the safe assumption that any monosaccharide can fill the role. I have the feeling that I'm very wrong. But I really wanted to know before assuming.
Thank you so much in advance <3
[Answer]
## Probably not, but other things can be.
The fact that DNA and RNA use a pentose backbone doesn't mean that any DNA analogue needs to have a sugary backbone, and not any random monosaccharide will necessarily work. The important thing about ribose is the *structure*, meaning the actual literal 3-dimensional shape and connectivity of the molecular fragment that makes up the backbone. In fact, it needn't be a sugar at all! Anything "close enough" to the shape of ribose and deoxyribose can theoretically be used as backbone alternatives in XNA. Things like peptides and even cyclohexene have been suggested.
[This website](https://www.atdbio.com/content/12/Nucleic-acid-analogues) has a good intro to a few suggested ribose backbone analogues, some of which are just altered ribose, some of which are completely different. For a more digestible and broad treatment, check out the Wikipedia pages on [nucleic acid analogues](https://en.wikipedia.org/wiki/Nucleic_acid_analogue#Backbone_analogues) and [xeno nucleic acids](https://en.wikipedia.org/wiki/Xeno_nucleic_acid).
[Answer]
## It must be a Pentose or a Hexose\*
\**may have exceptions*
From what I've seen the sugar must be a pentose, having 5 carbons, **or a hexose**, having 6 carbons. There are notable exceptions to this general rule of thumb, such as threose *which is a tetrose* having 4 carbons. It is also of vital importance for there to be a phosphate "pathway". Xylose may be a good alternative sugar, and I like that it has "X" in it like XNA. Xylonucleic acid (formally XyloNA) is also a thing, along with Deoxyxylonucleic acid (not sure of the abbreviation here). There are at least six currently investigated backbone sugars that are used in XNA research as shown in this [paper](https://www.researchgate.net/publication/346969843_De_Novo_Nucleic_Acids_A_Review_of_Synthetic_Alternatives_to_DNA_and_RNA_That_Could_Act_as_Bio-Information_Storage_Molecules/figures?lo=1) from 2020. XyloNA research has been conducted and this [paper](https://www.researchgate.net/publication/280123423_Xylonucleic_acid_Synthesis_structure_and_orthogonal_pairing_properties/figures?lo=1) from 2015 shows a comparison to RNA.
] |
[Question]
[
Medical-related question for my science-fiction story.
My character is in a facility with modern BUT limited medical supplies. This character is suffering from seizures due to withdrawal from a certain substance, and the doctor present has fruitlessly attempted to stop the seizures (using some form of benzodiazepine).
So, my question: I know that a last ditch effort for stopping seizures is a medically-induced coma. But in order to move my story along, I'd need my character conscious during this time. The facility DOES have sedatives, so it seems like a doctor would just put him under -- and sabotage my plot point! The only out I can think of is that the optimal drugs for knocking out a seizure victim aren't present in this facility. But would this really cause a doctor to hesitate sedating the patient? I'm not a doctor, so I don't know what the reasonable call would be.
Any sort of reality check would be appreciated!
[Answer]
Here is a good algorithm for status epileptics = uncontrolled seizures.
<https://emcrit.org/pulmcrit/status-epilepticus-2/>
[](https://i.stack.imgur.com/qYQvr.jpg)
The author is of the opinion that a lot of the bad effects from continued seizures has to do with the body moving. A way to stop the body moving is to paralyze a person with drugs. The body stops moving but the person then cannot breathe (because respiratory muscles are paralyzed), so you need a mechanical ventilator. It is unpleasant to be awake while paralyzed because it is scary, and so they sedate with propofol. Propofol will knock you out but good.
Your doc does not have seizure meds or what he has does not work fast enough. He paralyzes and sedates the patient and puts him on a ventilator while they send for different / better drugs.
If you don't want him to use propofol you can just have the seizing guy be paralyzed and on the ventilator. If he is having seizures that bad he probably won't be awake enough to be scared.
] |
[Question]
[
In my world, the Mayan Empire expanded into the Caribbean and met the relict ground sloths of the Caribbean. In this same world, the Mayan empire saw the use of these creatures as useful domestic animals that they could bring to the mainland. With pack animals to be used as beasts of burden, the Mayans could build even more amazing structures, and form an even more powerful civilization. They may not even have been dominated by the Spanish. Sadly, there is a problem with this idea. Could the Ground Sloths have been made in to viable pack animals?
[Answer]
Based on assessments of them being slower-paced in motion, having osteoderms, inturned claws on the front paws capable of tearing apart large branches, no incisors, and exclusively vegetarian diet in coproliths, I'd say it'd be possible, but probably no picnic to domesticate such a beast.
We cannot, of course, assess intelligence / intransigence, herd / individuated behaviour easily, so it's equally possible that they might be characterlogically unsuited to domestication; I'd guess though that if the people in question had a significant observational base of the behaviours of this mega-critter, it'd probably be do-able.
[Answer]
### Sloths are not very social but they are still mammals
Most domesticated animals come from species that form packs in the wild, with cats as a notorious exception. Social species are able to live together in a confined space more easily than solitary species (try to lock two adult tigers in a barn and you'll get an idea). Moreover, their social brains allow them to "empathize" with human moods and feelings (e.g. dogs, [camels](https://en.wikipedia.org/wiki/The_Story_of_the_Weeping_Camel), [horses](https://www.bustle.com/p/do-horses-like-humans-a-new-study-shows-that-they-understand-our-emotions-8969931)), and make them less likely to resist or kill their masters whenever they have a chance (google *tiger accident circus* to get a taste of this stuff... jaguars are worse, no circus dares to tame such beasts).
Unfortunately, it seems sloths are not very social animals.
This is an excerpt from a [paper on social behaviour between sloth mothers and their young offspring](http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-69842002000200008).
>
> Social interactions among sloths are considered to be rare, mainly because these animals are known for their solitary habits. However, some reports represent attempts to understand to a greater extent some of the sloths' social interactions in captivity or in the wild. In this context, a study focused on indirect contact through vocalization between mother and young of Choloepus hoffmanni and Bradypus infuscatus (= Bradypus variegatus) (Montgomery & Sunquist, 1974). It showed that vocalization is quite intense and important to communication in the first 6 months of total infant dependence.
>
>
>
However, since sloths are mammals, they do depend on mom and learn a lot of things from her. If your Mayans find a way to substitute sloth mothers and make them addicted to humans somehow, you could have some type of sloth domestication but very different from that of horses or dogs. Maybe you could look into the process of cow domestication to get some inspiration.
[Answer]
I am going to have to suggest that **no, sloths would not make good pack animals.**
I don't say this for any particular behavior reasons. As others have mentioned sloths are not particularly social, but this I think could be trained into sloth behavior if they were raised from birth by humans. We are pretty dang good at training animals.
**My concern is physiological.**
1. [Sloths move slow.](https://www.youtube.com/watch?v=ES32UFlPOUA) Really slow. While pack animals are generally not known for amazing speed, they do tend to be able to plod along at an at least human walking pace.
2. [Their limbs are adapted for hanging and grasping, not for supporting their weight](https://en.wikipedia.org/wiki/Sloth). Their bones, muscles and tendons are not meant for crossing overland. If you haven't clicked the link link in #1, watch it, it basically tries to scuttle along on its stomach. Their claws also curve back toward the forearm, they may be able to bend them the other direction, not sure, but they wouldn't be suited to walking on dirt paths and dragging a cart or sled behind them.
3. Their metabolism is really slow, they can also hibernate, or enter a topor (see the wikipedia link).
**All in all, nothing in their physiology suggests they would make a good pack animal.**
I suppose it is possible that you could selectively breed sloths to make them better pack animals...but it would take many many generations...you are essentially trying to make them... *not sloths*. Considering pre-colonial peoples had already domesticated llamas as pack animals it doesn't really make sense to basically completely change the physiology of a creature.
On a cool side note the wikipedia page says a sloth can hold its breath underwater for up to 40 minutes due to its slow metabolism...which is neat.
] |
[Question]
[
A religious order has learned that the Big Bad wants their MacGuffin. They have contracted a local adventurer to prepare their defense as best he can before the enemy arrives. What is the most urgent thing to take care of to maximize their chances of survival?
They live in a stone compound that is mostly self-sufficient. A forest just outside provides raw material for construction, and they have a small stockpile of iron and bronze for building tools. The technology level of the world is vary low. The knowledge to build e.g. crossbows and siege engines has been lost. The world outside has fallen into anarchy, so no hope of help.
The inhabitants have no fighting experience, but about a third of them are accustomed to hard manual labor.
The enemy, as far as anyone knows, are not experts in siege warfare. They are closer to a gaggle of idiots with about an even chance of transporting primitive explosives to their destination without blowing themselves up.
[Answer]
Your order has a couple of very useful options to their disposal. Any adventurer with minimal siege experience would agree. This isn't the stuff of tactical geniuses.
**1) First you'll clear the forest around the monastery.** Regardless of your ranged weaponry you want a clear line of sight. In the very least to prevent the enemy from sneaking up on the compound. So clear the forest, stockpile the wood inside for other projects.
**2) Dig a moat.** No need to fill it, just dig a deep moat and on the inside create a wall of wooden stakes. Preferably put some stakes in a more forward position. This forces the attackers to either work their way through the stakes in the open or use the designated entrance where the defenders can concentrate their defenses.
**3) For weapons your order will mainly make two weapons**, maces and spears. Spears were probably till the invention of the gun the most deadly weapon in all of history, maybe even up till the first automatic weapon. Spears are easy to use, cheap to make and create distance between you and whatever wants to hurt you.
Philip of Macedon trained his men into a phalanx in a single winter. Drilling with spears isn't that hard and I feel if you adventurer has seen some form of phalanx or hoplite warfare before he could drill them.
Your second main weapon will be a mace. Bronze headed maces are easy to make and even easier to use. There is a reason they existed well into the middle ages. Bronze is denser then steel. That makes a bronze mace head heavier then a steel one of similar size.
Maces have another advantage over swords and axes. They don't need edge alignment. A mace head doesn't have a cutting edge. The mace doesn't really care with what aligned you hit your target. Edge alignment is a skill, a skill I doubt your order has the time to master. Be smart and stick with maces and spears.
**4) Touch them from afar.** Your order should try and get their hands on ranged weaponry with all their might. Having them in combination with a wall is a huge force multiplier. They should have some hunting bows I imagine. They live next to a forest after all.
Making more bows will be difficult. Bow making is an art, one that takes a long while to master. Not only that but good bow wood takes months to dry before it can be worked with. Simply put, they don't have the time to dry the material and practice. Unless we're talking years before the enemy shows up.
What they can make and train with are javelins and slings. Javelins don't require fletching and you're stocked up on wood from clearing the area around the compound. Metal tips is optional, unless your enemy is fully clad in mail wooden tips will hurt.
That brings us to slings. Slings are amazing, easy to make and easy to learn to use. They don't require exceptional physical strength unlike a longbow. Ammo will be plentiful, small stones, a finger shaped mold with lead for increased penetration.
[This](https://www.youtube.com/watch?v=FaQRNj0WpYU) is an excellent video on the ease of use and lethality of slings.
Armed with slings from the walls your order could rain down death upon your enemies far before they reached the moat/ditch and the stakes. Accuracy isn't paramount in a volley, just launch at the blob of enemies with a few dozen men.
**Note on crossbows**, crossbows can be complex metal instruments of death but they don't need to. Crossbows go back as far as at least 500BC. As far back as 400BC they were a staple of the Chinese military. They became particularly popular in Europe around 500AD when Germanic migrators moved through Europe. They carried crossbows for hunting purposes, not warfare. A simple Greek crossbow from antiquity:
[](https://i.stack.imgur.com/XAS3i.jpg)
They're actually great tools for hunting, far easier to shoot then a bow. And animals don't wear armor. There is no need for a hard to span crossbow when you hunt deer. The animal is relatively close by and a soft target. I really think your order will have a nice collection of hunting crossbows.
Regardless, crossbows aren't easier to make then regular bows. They still require the bow part which takes to long to make so no additional crossbows will be available.
There several other preparations your order then undertake but I'm not 100% sure how certain your adventurer would know them. Stock up on water and cover any easily flammable roofs like reed. Fire arrows had a huge and lighting roofs on fire was one.
Create covers for the windows so you can lean out while being shielded from the sides and top. Keep the bottom open so you can throw stuff at the enemy.
Sketch:
[](https://i.stack.imgur.com/mPMv6.jpg)
A, Moat with stakes. Horizontal one is buried at ground level. Keep them apart enough that it won't function as cover. But not so far apart the enemy can easily carry ladders or move in a shield wall or testudo like formation.
B, I assume the walls are more a thick outer wall of some of the buildings then a true fortified wall that can be patrolled. You'll need to build wooden fortifications instead. This was actually quite common. A lot of walls had a row of holes near the top one could fit a thick beam in. On top of this row of beams one could build wooden fortifications.
They would need to be build in such a way that the bottom has a hole to attack the besiegers with. This can simply be throwing down heavy rocks but also boiling pitch, arrows, bolts and javelins.
C1, variation if your wall lacks any system to put in beams you might want to build over the interior buildings. This is also a good idea if the roofs are vulnerable to fire. Planks covered in soaked hide is much harder to ignite.
C2, Topview of the above.
D, it could even create an interior walkway. Might protect the ground from projectiles as well.
E, an experienced defender would insist on two ditches. An outer one with stakes to slow down the attackers without providing cover and a second inner one. The inner one would have a wooden bridge at the gate(s) that can easily be destroyed, denying it's use to the enemy. That second ditch should also be filled with some stakes if only to prevent the enemy from charging the walls directly.
F1, exterior ditch with the stake setup of A. Earth should be placed inside to create a minor earthen wall to secure the stakes in.
F2, interior ditch with simple vertical stakes. Can be shallower then the exterior ditch.
F3, outer wall of the compound. As I picture it inside there is a collection of buildings. Their outer walls are reinforced and connected, creating a compound. From the top left clockwise:
Entrance and lodgings for travelers, workshops, tower with sundial and messaging system like a bell, storage, (vegetable) garden, waste disposal/latrine, storage, sleeping quarters, mess hall, inside the main temple can be found.
F4, primary well.
F5, secondary interior well.
[Answer]
Bah. Forget swords. Real soldiers used polearms and bows as their primary weapons on the battlefield. Swords were back-up weapons. If you don't have a lot of iron, then use them for spearheads, arrow tips and daggers. But given that the attacks have no siege engines the most important thing to survive is enough food and water to outlast them. The defenders need to fill their storehouses because if the attackers don't have siege weapons and the defenders have walls then the options for the attackers are:
1. Get a traitor to let them in.
2. Start digging.
3. Starve the defenders out.
Yeah yeah, ladders are also an option, but these guys don't sound like they can make a good long ladder.
[Answer]
This is a medieval setting so of course God is *the* most powerful force.
The order are friends of God and so they should rely on his mercy by praying extra hard, self-flagellating and undertaking works of charity in the neighbourhood.
If they do this hard enough then God will either rain fire on the enemy, cause them to blow themselves up, or simple make them more confused than they already are and send them in the wrong direction.
Of course, as a precaution, the order should securely hide the MacGuffin and substitute a counterfeit. If the baddies manage to even get there, the order can hand this to the baddies with only a token show of resistance.
] |
[Question]
[
In the story I'm building, a 3rd atomic bomb (same spec as Fat Man) was created for use on Japan - and dropped.
However, for whatever reason, the 3rd bomb never detonated - impacted the ground and became burried in the ground (as many unexploded munitions from WW2 have been).
In the story, the bomb is to unexpectedly detonate years later - causing political turmoil and accusations.
**What is the longest this atomic bomb could be left underground, and still have the potential to detonate?**
To extend the timeframe, it is perfectly acceptable to use *extremely unlikely but technically possible* circumstances that explain away blockers things like "atomic weapons had a 3-day activity due to needing batteries replaced".
It is also acceptable for the bomb to have detonated due to a natural event, or regular construction event (or similar), so long as nobody knows about the bomb untill it detonates.
[Answer]
# You can always get a *fizzle*, and that is bad enough
The Fat Man design depended on an [**initiator**](https://en.wikipedia.org/wiki/Modulated_neutron_initiator). The initiator sat in the middle of the plutonium core, and when the plutonium was imploded, this crushed the initiator, that then gave an initial "spark" of neutrons. This spark kick-started the chain reaction and gave it a sort of initial boost that was essential to get the full effect of the weapon.
The "urchin" — as it was called — was based on polonium. That polonium isotope has a very short half-life of only ~138 days (this is necessary to get the neutrons needed, something that does not decay quickly does not give off neutrons!). This means that its efficiency drops by a factor of 10 about every 450 days. So in only 4 years, it would only produce 1/1000 of the number of neutrons it did when it was dropped. So you will not get a full blast out of this weapon, probably not even after one year.
## However...
There are two factors that will still make this thing a very hot potato...
1. It can still go "prompt critical" if it is initiated. And even if the result is only a *fizzle* — as a failed bomb is called — the chain reaction will still cause "dirty" fallout.
And even if you do not get any chain reaction, by having only part of the conventional explosives go off, or going off with poor efficiency after that long time, you will still make powder out of the plutonium core. Although plutonium is not much more toxic than lead (\*), the psychological effect of that will be **gigantic** and have people fleeing the area as if Death itself was standing there.
2. People are **terrified** of nuclear bombs and radiation — especially so in Japan — and the scars of Hiroshima and Nagasaki run very deep in the Japanese nation. The "soft" fallout of this will be enormous, even without the bomb itself making another mushroom cloud.
And in any case: **no-one will know for sure that it will not blow up**. Do you(!) want to be the explosive ordnance disposal person that wanders up to this thing and tries to find out if it will blow up or not? The conventional explosives in this thing are enough to make you into fine red dust. And the usual method of disposing of old explosives — which is to vapourise them with other explosives — is **completely** out of the question.
So to summarise: you cannot get a **full** yield of the same kind that destroyed Hiroshima and Nagasaki, and that state will happen probably within a couple of days when batteries and capacitors run out, for sure within a year as the initiator decays. But(!) you will have a very effective plot hook in that this this thing is still **political** dynamite in the kiloton range, and everyone will be going around it on tippy-toes both figuratively and literally because the materials still left in it are in an unknown state and are still enough to kill a few people and cause a mass panic if it does blow up.
(\*) The myth about plutonium being the most toxic substance on Earth is completely bogus. The botulinum toxin for instance is at least 1000 times more potent per unit of mass... and people inject **that** stuff into their faces to smooth out wrinkles.
[Answer]
This is unlikely enough that if you want to go down this path, you should just handwave it and forget about it.
The first thing to note is that if you dropped a bomb like that, it won't just bury itself. It will decelerate rapidly, breaking things. You will not have a functioning bomb after it hits the ground -- you will have a pile of radioactive junk.
But let's say the bomb wasn't dropped. Let's say we hiked it in on a humvee, and burried it by hand.
Now you have to deal with the issue that there is an *enormous* amount of interest from nuclear powers to not have their bombs go off if they fall into enemy hands. This means they are unlikely to go off without an intelligent adversary actively trying to make it happen.
Setting off a nuclear bomb is actually not easy. To do this, we invented the "exploding bridgewire" initiator, capable of detonating several charges all over the bomb with a tolerance of about 100ns. These are not easy to set off intentionally. Having them go off by accident is highly unlikely.
So basically, we're going to have to assume the following scenario: The US military hands all of our nuclear weapon secrets to an unstable mad scientist, who intentionally creates a bomb designed to sew confusion. He designs a bomb with a timer that is *designed* to go off as late as possible.
Then he buries it.
Now the limit is going to be the shelf life of the material. The nuclear fuel isn't going anywhere. U-235 has a half life of 70 million years. Plutonium's half life is lower, ranging down to as low as 14 years if you use P-241, so there's no reason he'd choose this.
Atomic bombs are dependent on conventional explosives to set them off. If you use RDX, it's shelf life is about 5 years. That would be a major limiting factor. Fat boy used RDX and a few other carefully balanced explosives to achieve its goals. As they decay, this balance would be thrown out of whack.
To simplify things, you could design your bomb after Little Boy, rather than Fat Man. Little Boy's design was much simpler. Little boy only needed a "gun" to fire a ring of material down the body of the weapon. This gun was powered by cordite, and we've got documentation suggesting cordite can stay "good" for 100 years or longer. Also, because it's not a complicated timing-critical process, you'll have more slop room for it to continue functioning as the cordite decays.
Beyond this, your main limit will be the lifespan of the battery. If you use a thermal battery, you may be able to get this into the decades.
[Answer]
So let's say our hypothetical fat man used a wind safety, but instead of driving the detonator into the charge, for some reason, this one-off was designed so that the spinning propeller charges the detonator. This leaves the bomb failure plausible, and the detonator could be in any state depending on static charge buildup.
The explosive (RDX) is stable at room temperature. It is biodegradable, but that would depend on that case being compromised.
A charge failed and a "soft" landing through tree canopy, roof, hay, and/or mud makes this plausible.
The uranium in nuclear weapons is generally enriched to 90% U-235, but only 20% is required for an explosive reaction. I don't know how well fat boy was enriched. The half life of uranium is 4.5 billion years, so about 9 billion years for the fuel to decay due to half life.
The electronics and the detonators themselves are likely the weakest links. Depending on insulation and the presence of oxidizers it's extremely variable. In ideal conditions (such as the Edison bulbs) one hundred years is amazing, but not without precedent.
] |
[Question]
[
Alright, departing from my usual fantasy setting to something of a thought experiment. Let's say, for argument's sake, some Dane longboat captain in the 10th or 11th century worked out how to make a primitive compass and, while serving in the Varangian Guard, read about the shape and size of the Earth. Extremely unlikely, I know, but humor me. This hypothetical Dane would, in other words, be an extremely capable navigator and explorer.
Anyways, let's say he made his way back to Denmark and resolved to sail west past England, and discovered places like the Faroe Islands, Iceland, Greenland, and Vinland/Canada. From there, imagine that he returns to Denmark, gathers up a bunch of Danes, and makes for Vinland to set up a colony. How quickly could he sail from Denmark to Canada, without stopping? Assume he's got good weather and favorable winds, as well as a top of the line longboat for the day.
Now, for further fun, let's say this Dane established a successful colony in Newfoundland, and his son was hell-bent on outdoing his father in the exploration game. How far down the coast of North America could he conceivably make his way before he had to return to the colony for resupply?
[Answer]
The [Draken Harald Hårfagre](https://www.drakenhh.com/), a reconstructed Viking longboat, made the crossing from Norway (not Denmark) to Newfoundland in a little over five weeks in the spring of 2016. From their website, [here's a description of the voyage:](https://www.drakenhh.com/expedition-america-2016/)
>
> On April 24th 2016, Draken Harald Hårfagre set sail across the icy north, beginning Expedition America 2016. Due to tough weather Draken made two portstops on the way to Island [Iceland]. April 27-30 in Lerwick, Shetland, to replace the starboard shroud and May 1-6 in Torshamn, Färöarna [Faroe Islands] to repair the sail. The first stop was in Reykjavik on the 9st of May, and celebrated the arrival to the Viking island of Iceland in proper fashion. From Iceland we sailed for Greenland, rounding the treacherously windy and confused seas of cape Farewell and Greenland’s southernmost tip. We needed to dodge the sheet ice to seek refuge in the port of Qaqortoq in Greenland’s south western fjords. From Qaqortoq we sailed across the Davis Strait, a thousand miles north of where Titanic met her fate, maneuvering past icebergs for Newfoundland, Canada. Our first stop in Vinland was St. Anthony harbor and the known viking settlement of L’anse aux Meadows tentatively the 1st of June.
>
>
> ### Portstops
>
>
> * April 26: Haugesund, Norway
> * April 27-30: Lerwick, Shetland
> * May 1-6: Torshamn, Faroes
> * May 9-16: Reykjavik, Iceland
> * May 21-27: Qaqortoq, Greenland
> * June 1-6: St Antony, Newfoundland, Canada
>
>
>
Note that approximately half of the transit time was spent in port performing repairs & resupplying; the actual amount of time spent under way seems to have been about 16 days. However, you'd also have to add a couple of days to account for the time needed to sail from Denmark to Norway, and a realistic voyage would probably require *some* time for resupply along the way.
All told, three weeks or a bit less seems like a reasonable estimate for a "lucky" voyage.
[Answer]
For the trip from Denmark to Vinland I'm using AlexP's distance statistic for the Viking route heading north and east, roughly 2800 miles (approx. 5200km), because I can't find an estimate I'm confident of. Based on that and an [estimated top speed](https://en.wikipedia.org/wiki/Longship#Characteristics) of 15 knots (28kmh-1) the trip would be roughly 185 hours, call it 8 days. That's with a perfect and consistent following wind but that's highly unlikely to be the case for the whole voyage. At the average speed, around 7 knots, it'd be about more like 400 hours, or 17 days.
Exploring farther south will depend on what size ship(s) are used more than anything else; that's something you'd have to decide on. The important variable being the cargo-to-crew ratio, how much food and water the ship carries per head of crew needed to work it effectively. The ships will cover an average of about 165 Nautical Miles (310km) a day sailing around the clock, they can do that if they have sea room but if they stay close to shore, (and depending on the season) they'll get less than half of that.
One thing to keep in mind is that the European Windstorm Season, when the vikings would normally stay in port is September to March but the North Atlantic Hurricane Season, which will impact any trip south along the American coast from Newfoundland, is June to November. Setting out for a long exploration voyage during the traditional Viking sailing season could be totally disastrous.
] |
[Question]
[
In one of the documentaries he's featured in, Neil deGrasse Tyson talked about the evolution of the eye.
<https://www.youtube.com/watch?v=4SXHMm5I-68>
The part that's always intrigued me is this:
>
> Our eyes originally evolved to see in water. ... For land animals, the light carries images from the dry air into their still-watery eyes. That bends the light rays, causing all kinds of distortions. ... Our vision has never been as good since [our distant ancestors left the water to live on land]. ... 375 million years later, we still can't...discern fine details in near darkness, the way fish can.
>
>
>
I can think of at least two world building applications for eyes that evolved in air. In a fantasy setting, creatures that evolved in an elemental air plane, such as the Aarakocra in some retellings of the D&D multiverse, might have very different eyes from ours due to the relative lack of water in their home environment.
In a sci-fi setting, transhumans who want to "correct" our water-based vision to see better might re-engineer the evolution of human eyes.
## ***So, what would eyes that evolved in a "dry" gaseous atmosphere be like in comparison to the ones humans have now?***
---
Edited for clarity:
I'm looking for how plausible and informative the response is regarding the physical structure of eyes that evolved in air instead of water. Thus the emphasis on what they would "be like," and the suggestion to compare them to the eyes we have now.
I specifically left out anything having to do with bacteria in deep time because, while I'd certainly consider such details supportive of the overall answer, the history of how and/or why the structures evolved seems to be its own unique question, and the site generally frowns on more than one question per... question.
[Answer]
They would look like pit viper pits--or at least, *one kind* of eye that can evolve in air looks like pit viper pits--because that's *exactly* what a pit viper's IR-sensing pits *are*. They are a real-world example of a new eye evolving in air, rather than water.
It basically goes the same way as evolving an eye in water. You start out with a simple light-sensitive patch. Then it develops into a cup, or pit, to allow for better directional sensing. This is where pit viper evolution has stopped, so far. But the next stages would still be pretty much the same to get to more advanced eyes. Either you develop a lens, enclosing the eye and filling it with pressurized gas (rather than liquid) in order to maintain its shape, or you split the retina and develop a mirror arrangement (like scallop eyes), in which case the whole structure can remain completely open. It is still *possible* for such a structure to be enclosed anyway, and supported by internal pressure, but otherwise it would simply be made out of more rigid materials.
There's also the example of arthropod compound eyes. Those *happen* to have originally evolved in water, but they didn't have to. Compound eyes are not filled with liquid, and their evolution would proceed identically in air.
Incidentally, pit vipers had a real evolutionary pressure to evolve an entirely new set of in-air eyes, rather than just continuing to adapt their existing water-filled eyes, for two major reasons--they rely on seeing other animals' body heat for hunting, but water-filled eyes cannot see infrared, because water absorbs infrared.
[Answer]
To maintain the highest degree of clarity and sensitivity, the [effective refractive index](http://www.cs.cmu.edu/~ILIM/projects/IM/aagrawal/cvpr12/CVPR12TalkFinal.pdf) of ocular elements would be as close to one as possible. That would mean the equivalent of a lens could not depend on thinning and thickening to focus light on the focal plane. So, I think they might be in the form of a [Fresnel lens](http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/fresnellens.html) with adapting ridges to permit focusing at different depths.
The lens itself would likely be multi-layered to keep the size of the eye down. The higher the index of refraction, the more the light can be bent and focused. So a constant index of refraction would result in a wide and deep eye.
The photoreceptors might be very different too. Rather than setting on a curved surface, they might just be separate planes of transparent for each wavelength of the creatures visual spectrum. These would be similar to our cornea, it's a transparent covering densely covered with nerves -- I cut mine once and it hurts. In these creatures though, each plane of nerves would only absorb energy at a specific range of wavelengths. This would give them a very sensitive vision that could see threats and prey from great distances and even sometimes by their IR emissions, IR shadow, or UV reflections.
[Answer]
Our eyes is basically a layer of photosensitive cells together with a diaphragm to control the amount of light passing through a lens, which focus the light on the photosensitive layer.
From a mechanical point of view, having the space between the lens and the photosensitive layer filled with liquid helps keeping the shape of the entire device, and makes also more precise to control the lens via muscles: try squeezing a bottle filled with air and one filled with water, and see where you have it easier.
Not using the liquid would probably mean choosing between two paths:
* sensitive layer with no lens: would not go further than detecting movement and light/shadow difference, I am afraid.
* use bones or cartilage to build a container for the eye.
[Answer]
One possibility could be eyes that look like that of [Chameleons](https://en.wikipedia.org/wiki/Chameleon_vision).
The smaller surface area would reduce the rate of loss of water from the corneal surface, while the unique monocular focussing might keep the quality of vision of similar quality as that of normal eyes.
[Answer]
Our eyes are filled with liquid because we evolved from water.
A life that evolved in air will likely have eyes filled with gas.
So basically a sac filled with transparent gas, surrounded by muscles to move it and change its shape. I know fish have a "gas bladder" to help with depth control, so air-filled sacs are feasible.
] |
[Question]
[
Bird wings are made mostly of feathers, and there's about a million articles out there on that subject. Bats, on the other hand, have wings made largely of skin and bone. These are flexible, giving bats incredible flight capabilities, but extremely fragile: a paper cut would rip a gash through them.
What I'm trying to figure out here is fairly straightforward: could a creature have working wings (meaning here that they would allow the creature to fly under its own power) made up primarily of keratin? If so, what would be the major benefits and downsides? More durable wings seems obvious to me, especially if they end up like [pangolin](https://en.wikipedia.org/wiki/Pangolin) scales, but that wouldn't be the only effect.
For the purposes of this question, this needs to be a biologically plausible creature; picturing a modified bat is convenient, but you're free to imagine something else if you prefer, even a dragon! Although not strictly necessary, bonus points if the answer also covers how evolution might lead to developing these keratin wings, and double points if the whole creature ends up armored like a pangolin wings and all.
Edit for clarification: I didn't mean "keratin" in the sense of feathers, since I'd managed to forget that particular fact (quite embarrassing). I was picturing more of a bat wing, but something harder and solid, either in scales or as a single piece. I am aware that this comes with a weight cost; if it's flatly unfeasible (not just more energy-intensive, which would fall under disadvantages) for a creature to fly with such wings, that does (regrettably) qualify as an answer.
[Answer]
Well, [keratin](https://en.wikipedia.org/wiki/Keratin) is one of the key proteins found in skin, hair, horns, feathers, etc. So basically, your average bat answers the question pretty well (thin skin wings), and your average bird even better (feathery wings)!
Bird feathers are about [75% keratin](https://pdfs.semanticscholar.org/c72d/3cb1ded22997f6aa85ded41f8f1180d9d1aa.pdf); and they have been flying like pros for a few years now, so clearly their keratin based wings "work". Keratin is present in the epidermis, but not to that great a degree. In a bat's wing, there is also muscle and vascular tissue, nerve tissue and the like that is absent in most of the feather.
Pangolin scales probably would not be very suitable for the wings of a flying bird, at least not completely. Large heavy scales would mean most likely that the bird will be flightless, and would thus be using its wings for purposes other than flight. Fighting or hunting maybe? Just imagine one of these bad boys with thick keratin scale armour! ---
[](https://i.stack.imgur.com/cnj7C.jpg)
I would imagine a hybrid creature: keratin feathers on the body & wings for flight as per normal everyday birds. But reasonably thick keratin scales in key areas: bird legs already have keratin scales, but perhaps make them a little larger for fighting; integrate some scales along the forward surface of the wings and perhaps along the crest of the head for display and defense.
The key constraint here is flight, and I think you'll not really be able to do much better than feathers if you want to keep your birds flying! Working wings can be used for so many more things than just flying, but weighing them down with heavy armour will defeat your basic premise.
In light of the question edit, I might also posit a more "leathery" bat wing: still relatively thin and pliable, but with thin keratin sheet-like scales. Have to be careful, though, because the internal structure of a bat's wings allow their skin and tissues to fold in certain ways which we don't want to mess with. Bats use their wings for purposes other than flight, such as climbing, creeping on the ground and fighting. Some (slightly) heavier keratin scales might serve this animal as a bit of extra protection. Tougher wings, though after reviewing a number of bats fighting videos, I am not actually convinced they would get much benefit from the extra armour!
[Answer]
Yes, and it need not come at the cost of extra weight.
Consider insect wings. They are made of chitin, the same material that forms their exoskeletons. It's hard and scaly, but insect wings are *not* heavy, because they are *thin*.
Keratin is slightly less dense than chitin, so the wings could be sturdier than the typical insect wings and still not be too heavy.
What kind of creature might have such wings? Well, the obvious answer is alternate-world insects that use keratin to build their exoskeletons instead of chitin. They would certainly be armored head-to-toe, just like real-world insects and pangolins! And they needn't even be particularly small; ancient dragonflies got downright enormous. They just need enough oxygen in the air to support that growth.
But starting from something in the real world, wings made of hair might work. One could imagine a particularly fluffy creature that doesn't develop skin-flaps like a bat or flying squirrel, but is small enough that it gains some protection from falls due to being so darn fluffy that its fluff actually significantly increases air drag, reducing terminal velocity. At the next stage of evolution, flattened, matted hair, serving a similar role as a flying squirrel's skin membranes, might provide greater control over falling / gliding. And from there, you might eventually get to something that is able to grow orderly sheets of keratin from its arms, similar to a single enormous bird feather, composed of specialized hairs with micro-barbs that allow them to lock together. This wouldn't be particularly extra-durable, but would have the advantage of painlessly and repairably deforming against stresses that would severely injure a bat. Just like the vane of a bird's feathers can develop breaks, but be repaired by proper grooming to re-attach adjacent barbs, this sort of single-feather wing could separate under strain, but be easily joined back together again afterwards.
] |
[Question]
[
**This question already has answers here**:
[Rambo style compound bows, feasible with renaissance tech-level?](/questions/67446/rambo-style-compound-bows-feasible-with-renaissance-tech-level)
(5 answers)
Closed 5 years ago.
I am thinking if it's possible for craftsmen of late medieval times to achieve precision required to repeatedly make crossbows enhanced by use of cams or pulleys. As far as I know, pulleys were used in medieval societies quite often, but I don't think they were made in sizes approaching the ones required for compound crossbows.
But, assuming medieval military engineers figured out putting pulleys on ballistas or crossbows would bring some advantage and then found some skilled craftsmen to build parts and find good materials for it, would it be plausible?
Edit to address duplicate votes:
It's true that my question is really similar to this one: [Rambo style compound bows, feasible with renaissance tech-level?](https://worldbuilding.stackexchange.com/questions/67446/rambo-style-compound-bows-feasible-with-renaissance-tech-level)
but I believe this earlier thread was a bit more about a compound bow specifically (with features like detachable arms) and I think that answers provided under my question give some new information and thoughts on the topic.
[Answer]
The closest analogues to what you describe are the [Ballista](https://infogalactic.com/info/Ballista) (torsion catapults) of ancient antiquity. While not using pulleys and cams the way modern compound bows do, they were amazingly intricate mechanisms which could shoot javelins or large rocks hundreds of metres, and certainly not to be trifled with.
[](https://i.stack.imgur.com/aAAxf.jpg)
*Typical ancient torsion powered catapult*
Indeed, in Roman times, the technology had become so standardized that the Legions had a man portable device known as a "[Scorpion](https://infogalactic.com/info/Scorpio_(weapon))", which served a similar purpose to crew served weapons in a modern army.
[](https://i.stack.imgur.com/BV3RI.png)
*Reproduction of a Roman Scorpion*
Looking at this, you may wonder why Scorpions and Ballista disappeared before the end of the classical period, and the answer is brutally simple: cost. The materials used to make Ballista and Scorpions would have to be of high quality to withstand the stresses of the torsion springs, but more importantly, a highly trained *Ingenium* was needed to do the calculations to ensure the torsion springs were tensioned correctly and all the parts were properly assembled. As the resources to maintain this pool of skilled workers declined, the ability to build and use Ballista and Scorpions faded as well.
This leads to why compound bows were *not* invented in Antiquity, the Middle Ages or in fact until the 1960's. Bows were a very highly developed technology already, with literally tens of thousands of years of development behind them, and specialized bowyers who knew the craft of making them. The principles of mechanical advantage were also well known from ancient times, but the sorts of people who used pulleys (sailors, construction workers) were generally not involved in combat. Interestingly, the two were combined in the late Middle Ages and early Renaissance with the introduction of "spanning" devices to draw heavy steel bows.
[](https://i.stack.imgur.com/cjoRI.jpg)
*Crossbow with windlass spanning mechanism*
And this explains exactly why compound bows were not invented until the [1960's](https://infogalactic.com/info/Compound_bow). A steel bow with a windlass spanner could have a draw weight of up to [1200 lbs](https://todsworkshop.com/blogs/blog/crossbows-spanning-methods), providing *more than enough* energy to propel a quarrel capable of killing or injuring an armoured man. Both the bow and the windlass were relatively inexpensive, and were simply extensions of existing arts. No highly trained engineers would be needed to set up the bow, or make the adjustments needed to maximize the energy delivered, and both the bow and spanner would be relatively simple to repair in the field by currently trained bowyers and engineers.
So the issue isn't that people were not "smart" enough to invent compound bows, there simply was no *need* for compound bows in that period, since existing equipment could be made, maintained and used by people with existing skillsets, and was quite capable of doing the jobs demanded of them. Extra costs will *always* be ruthlessly pared away, and the cheapest, most capable pieces of equipment will generally be what you will be using.
[Answer]
Hero of Alexandria illustrated examples of cranes using early [block and tackle](https://en.wikipedia.org/wiki/Block_and_tackle) systems, so the concept and technology certainly existed.
The real problem is the connection point at the tips of the limbs. The pulley system makes it easier to draw, but it doesn't reduce the actual force in the limbs at all. Therefore, the force on the tips of the limbs is... impressive.
You could simply bolt a chunk of metal on the tips, but that means you lose all the flexibility of the tips and that's no small thing. You could gain some of it back by making longer limbs, but one of the bonuses for crossbows is their compact design.
However, you need to remember that compound bows are NOT stronger. The pulleys make them easier to draw, nothing more. Crossbow solved that problem with levers and cranks which often had the advantage of automatically notching the string. It's altogether likely that adding pulleys to the mix wouldn't add substantially to the drawing process and the technical drawbacks, in my opinion, make this a net negative.
**Answer:** Yes, they could do it. No, it's likely not valuable.
[Answer]
While Thucydides and JBH have focused on the weapon, I will focus on the ammo.
Bows work by transfering the energy stored in the bent arms or pulley/cam system onto the arrow. The arrow then gets accelerated from its still position to bat out of hell in very little time. If you see them in slow motion, you will see that in most kinds of bows (all non-compound, and some compound ones) the arrows bend while in flight. The more energy you give it, the greater the bending.
Wikipedia has the following to say about [arrows for compound bows](https://en.wikipedia.org/wiki/Compound_bow#Arrows_used):
>
> Arrows used with compound bows do not differ significantly from those used with recurve bows, being typically either aluminum alloy, carbon fiber, or a composite of the two materials. **Wooden arrows are not commonly used on compound bows because of their fragility**. Most arrows in use today are of the carbon fiber variety. (...)
>
>
> Another important consideration is that the IBO (International Bowhunter Organization) recommends at least 5 grains of total arrow weight per pound of draw weight as a safety buffer. This means a bow that draws 60 lb would need at least a 300 grain finished-with-tip arrow. **Shooting arrows lighter than this guideline risks damage to the bow similar to that caused by dry-firing, which can in turn cause injury to the archer or anyone standing nearby**. Shooting arrows that are too light also voids most manufacturer warranties.
>
>
>
Look at the ammo used by the roman scorpion. Those things look more like javelins or spears than arrows. If an archer were to use a medieval compound bow, the arrows would have to be made of steel. But arrows need to be mass-produced in ever greater quantities than melee weapons to make sense in a war - it would be too wasteful. Besides, whenever you did not massacrate your enemy, you would be giving them free steel for them to recycle into new weapons.
If a single archer were to use such a bow, they would have a hard time either producing or finding the arrows that would not break upon being fired.
---
That is not to say that you couldn't have a compound bow in the antiquities. If you do a quick search on youtube you will find plenty of videos teaching you how to build a compound with wood or PVC. They will shoot reguar arrows... It's just that they are not as strong and precise as a proper sports/professional compound bow, so there would be no advantage to using them in an antiquity setting. You would just be adding more upkeep costs to an already high maintenance weapon.
[Answer]
Yes, the ability to create shapes with enough precision for a compound bow existed. As a matter of fact, it already existed long before that.
What did NOT exist however: the material science. We just did not have the materials needed to make an effective and reliable compund bow.
] |
[Question]
[
I'm thinking of using this as a method of separating a planet's technological and cultural evolution, then having a sudden clash as the more advanced one becoming able to cross the storm belt. This would allow the tech to be about 50 years apart at the outset, one being at, say, the 1830s, and the other the 1890s.
[Answer]
# Yes: none of your land is near the equator
Where are the strongest sustained winds on Earth? In the roaring 40s (actually more like the Furious 50s) in the Southern Hemisphere. Why? Because there is no continents to to stop them! Winds pick up sustained speeds driving around the Earth in a circle with only a narrowing in the Straits of Magellan and a couple tiny islands to block them.
Desolation Island (or [Kerguelen Island](https://en.wikipedia.org/wiki/Kerguelen_Islands), if you don't like being dramatic) receives constant winds at at least 35 km/h, with gusts up to 150 km/h being commonplace.
But you want these winds to be in the tropics, so lets put all the continents in the Northern and Southern hemisphere, at least 20 degrees off of the Equator. Now lets see what the winds do
[](https://i.stack.imgur.com/ASJXm.png)
The southern edge of the Hadley cell in both hemispheres is going to push winds in the same direction, westerly. Now on real live Earth, there are all these Africas and Indonesias and Panamas and stuff in the way. So the wind driven currents hit these continents and deflect in complex patters that lead to an [Equatorial counter current](https://en.wikipedia.org/wiki/Equatorial_Counter_Current) in the Ocean which serves to attenuate the moving air masses. Without any continents in the way, the oceans will be whipped up to speedy 6 knots or maybe more, and the winds will move along at a hearty clip.
But that's not all! First off, if you take a look at currents on Earth, there are plenty of hot and cold ones meeting each other at the Equator.
[](https://i.stack.imgur.com/lSZwH.png)
Now imagine that the continents are sufficiently far away, and positioned just right so that cold currents never make it to teh center of the equatorial band. Lets say that the waters from 10 N to 10 S never mix with cold currents.
These waters, permanantly circling the Earth under a tropical sun, would get hot and stay hot. Hmm...what is it that hot oceans do again?
[](https://i.stack.imgur.com/t4UGp.jpg)
Instead of only having seasonal hurricanes in either hemisphere, you now have permanent hurricane breeding grounds in all your oceans in the 10 to 15 North and South ranges.
Hurricanes need both hot water and circulating currents to form. So plop some good sized islands, a Java or Japan, down right at about 10-15 N to form current eddies right on the edge of our hot equatorial circulating current. In the lee (to the West of, in this case) these islands, hurricane formation conditions will exist year round.
Now you have high sustained winds, frequent hurricane force gusts, and frequent actual hurricanes!
[Answer]
Similar to this questions answer : [How to create the eternal storm?](https://worldbuilding.stackexchange.com/questions/55398/how-to-create-the-eternal-storm/55474#55474)
First, I like the premise...would make for an interesting world.
Second...The answer is (unfortunately) not likely and potentially not possible, though the setup of the globe could lend itself to this model. Weather trends towards equilibrium and without a constant source of large amounts of energy being dumped into the system, it would eventually calm down. Actions like erosion is ultimately the winds energy being translated to kinetic and thermal energy, or evaporation of water due to wind, all take energy away from the system.
Jupiter is an interesting example as you can readily see a planet wide storm somewhat like what you are asking for here, but Jupiter possesses one trait that allows it...no land or ocean to drain the systems energy. Unfortunately (or perhaps fortunately for us living on rocky planets) this so far appears to be a trait only seen on gas giants.
I'll see if I can find a scenario where this could happen on a globe with land, but no promises...there is the fringe potential that all ocean around the equator along with a process that feeds heat into this system, but usually the equator is where the water warms not cools (If you wanted to have the effect, an explanation along these lines might make a pseudo science usable for a story)
[Answer]
Yes but not in a way that is useful for your story.
Jupiter has permanent storm systems circling the planet, so it's definitely possible. Unfortunately where one storm system ends another begins.
The storms on Jupiter are also orders of magnitude stronger than the storms on Earth. Furthermore even modern technology wouldn't be enough to cross a storm of that magnitude.
It's a cool idea though. I don't thing your readers would begrudge you handwaving the storm's existence if it makes for a good story.
[Answer]
Wow. Neat concept. Depends on how much you want to manipulate your world and make it non-earth-like.
Suppose a planet were caught at a lagrange point between two equal stars, at the Goldilocks distance. And make it tidally locked with a thick atmosphere. Both hemispheres would be in continuous light, but the dark ring would be in eternal darkness. I suspect one would get tremendous air currents at this juncture, and there would be considerable storm activity. It would be a zone that looses heat to space, sandwiched between the two hemispheres that both receive a lot of heat. Add a ring made of high mountains around it (some effect of having two stars), and I can't imagine how this region would be anything BUT unstable.
So you have three factors dividing the societies - permanent darkness, permanent stormy weather, and mountains.
However, societies on both sides would be in permanent daylight unless you had a super-large moon circulating the planet creating an eclipse every 'day'. The night, however, would be short-lived.
[Answer]
(I'm going to preface this with the fact that I'm no where near an expert in this field, and the following statement is a wild conjecture)
It doesn't seem possible to have a stable, localized storm on a rocky planet in the way that you want it.
---
But, you have something that greatly tips the scales of storytelling in your favor...
**A cool idea!**
---
A reader or audience's ability to *suspend disbelief* is directly proportional to how 'cool' your world, or a concept in it, is (see: Star Wars Jedi). I personally think your idea is cool enough that it would be fine to not worry about its possibility. If it does turn out to be possible, that's just a bonus.
] |
[Question]
[
We know that the Romans invented or used simple machinery like waterwheels, crank mechanisms and even simple steam and atmospheric engines, as well as what we would recognize today as clockwork, but for a variety of reasons, the Romans never got beyond individual pieces of bespoke machinery for particular applications, and certainly never triggered an industrial revolution in the first century AD, or any time.
What I would like to know is, assuming no large scale discontinuities like civil wars or the fall of the Empire, would it be possible for the Romans to have built a simple flying machine at any time, and what circumstances would possibly allow this?
Edit to add: For clarification, could the Romans have developed a heavier than air flying machine either with the technology available after the first century AD or evolved form beyond that point?
[Answer]
According to answers to [this question](https://worldbuilding.stackexchange.com/questions/141829/what-is-the-earliest-time-a-pulsejet-could-be-built), the Romans could possibly have manufactured an early pulsejet, which *may* be strong enough for powered flight. The reason no-one did before the early XXe century is that to even think about it, they needed modern scientific advances.
However, assuming some genius inventor like Archimedes reproduce the jam-jar design discovery, with a nearly empty alcohol pot set on fire with a small hole on top, and dedicates enough time, resources and cleverness to study it further, it *may* be possible for someone in the Roman Empire to have access to empirically-developed pulsejet designs.
Wings would probably be bat-like and rather inefficient to our standards, so the pulsejet would have to bruteforce itself into the air. I suspect its performances would be bad, its autonomy terrible and the noise truly awful (though that last one may be an advantage in some contexts). Veteran pilots would probably be deaf and develop serious health problems due to vibrations, but I doubt that would stop the Roman Empire, given the benefits of even such a crude flying machine.
Comments evoke hot air balloons as another, simpler option. They would probably not have access to enough silk to use it, so the performances would not be as good. I suspect it wouldn't fly when air is too humid. Charcoal would probably be the fuel of choice, being relatively high energy-dense per mass. Still, even a clear-weather, tethered hot air balloon would give serious military benefits.
[Answer]
Yes or probably, depending on your definition of machine.
Does anything that is artificial and able to stay airborne count? If so, the ancient chinese did it. From the [wikipedia article on kites:](https://en.m.wikipedia.org/wiki/Kite)
>
> The kite has been claimed as the invention of the 5th-century BC Chinese philosophers Mozi (also Mo Di) and Lu Ban (also Gongshu Ban). By 549 AD paper kites were certainly being flown, as it was recorded that in that year a paper kite was used as a message for a rescue mission.
>
>
>
Even if a kite doesn't count, I believe they could have built a primitive hang glider. They certainly had materials for a prototype, such as silk and many kinds of wood. The reason they never did is probably because they lacked the science and the motive. The very idea for something like that was only thought as feasible in the western world around da Vinci's time, during the 1500's. It would take a handful more centuries before someone could actually build a workable one. [But once again, romans were one-upped by ancient China:](https://en.m.wikipedia.org/wiki/Hang_gliding)
>
> The earliest forms of gliding had existed in China. By the end of the sixth century A.D., the Chinese had managed to build kites large and aerodynamic enough to sustain the weight of an average-sized person. It was only a matter of time before someone decided to simply remove the kite strings and see what happened.
>
>
>
(I love the last sentence for all the scientific spirit contained in it).
] |
[Question]
[
I'm writing a science fiction story set on a moon orbiting a gas giant. I want to understand how the world's day night cycle would appear from its surface and how the world might be affected by this particular orbit.
For the purposes of the story the world needs to be as Earth-like as possible. It is primarily tropical and is one of several moons orbiting the gas giant. The gas giant at times fills most of the moon's sky and at other times is absent. Also I'm assuming that on some nights the gas giant would appear lit up at night, like a much larger more luminous version of our moon.
I've assumed that the world will sometimes be cast into darkness as its view of its star is blocked by the gas giant. At other times a specific area on the world will be in darkness because it is facing away from the star (like Earth does) despite not being blocked by the gas giant.
Would this give the world two different types of night? How long would its days be? Would it have days or nights of varying lengths depending on where in the lunar cycle it was?
I'm also assuming that the world spins on its axis (in order to generate the required magnetosphere).
Although not strictly hard sci-fi, I'm looking for a way to frame this world's orbit that is plausible and also naturally occurring. I'm not looking for heavily maths based answers as I just need enough detail to frame the story, and physics is not my strong point.
Cheers for any help you can give.
[Answer]
The spins of all large moons in the Solar System are locked to their host planet, meaning that they always show the same face to the planet. This is sometimes called "tidal locking", and it's pretty much unavoidable for the case of a large moon (even in systems with many moons, like Jupiter's Galilean satellites). It looks something like this:
[](https://i.stack.imgur.com/i9jR6.jpg)
If you were standing on such a moon, the gas giant would always be in the same place in the sky. In the image, the little guy would have the gas giant immediately overhead.
Tidal locking implies that the day-night cycle is completely determined by the moon's orbit around the gas giant. The Sun will go through a full cycle of rising and setting once for every orbit the moon makes around the planet. There is no dark side of the moon: since it is locked to the gas giant (not the star) the whole planet will receive sunlight.
And, as you figured out, there will be a brief eclipse every time the planet passes through the shadow of the gas giant. This will happen at noon every day for the guy who has the giant planet immediately overhead and at midnight for someone on the opposite side of the planet (who never sees the gas giant).
More details on habitability of giant planet moons (focusing on Pandora):
<https://planetplanet.net/2014/11/18/real-life-sci-fi-world-6-pandora-from-the-movie-avatar-the-habitable-moon-of-a-gas-giant-planet/>
More details on how to calculate illumination (using a complicated example -- yours would be much much simpler): <https://planetplanet.net/2016/03/23/earth-with-five-suns-in-the-sky-when-would-night-fall/>
[Answer]
You can avoid tidal locking (as explained by Sean) by having a [spin-orbit resonance](https://en.wikipedia.org/wiki/Tidal_locking#Rotation.E2.80.93orbit_resonance) that’s a value other than 1:1. In particular, just as with planets, you can have features and conditions that favor an odd half multiple such as 3:2 (as is the case for Mercury).
The giant primary will not fill the sky. The minimum distance can be considered a healthy margin past the roche limit. This distance (and orbital period) [has been discussed here before](https://worldbuilding.stackexchange.com/questions/4460/could-two-planets-be-tidally-locked-to-each-other-so-close-they-share-their-atmo/21344#21344).
For the true size in the sky, plug in the diameter and distance. You’ve not filled in any information on your profile, so we don’t know anything about your current level of education — how to use the sin/cos/tan functions would be a math question, not worldbuilding.
---
So, imagine a situation where it rotates on its axis three times in the same time it orbits its primary twice. Put a couple coins on a table, mark a dot on the rim of the smaller one, and imagine the window as the direction of the distant sun. You really have to play through it to understand the apparent motions from an observer at the marked dot.
Meanwhile, the primary goes around the sun on a much longer time scale.
Now add [libration](https://en.wikipedia.org/wiki/Libration) into the mix. We can presume some significant orbit eccentricity because that’s a condition for favoring 3:2 over 1:1 (and if you’re modeling it, you’ll understand why!). This will cause a faster/slower motion of the primary on top of the smooth rise and set, as well as growing/shrinking.
There will be a special lattitude where the primary rises and grows, being largest when directly overhead. Opposite that is a point where the primary is *smallest* directly overhead.
That doesn't consider any *tilting* of the plane of the sattelite’s orbit!
[Answer]
I'll try to balance the two answers already given here, as one seems to be based a bit too much in hard science, though appears to be accurate as far as I can tell, and the other lacks a detailed description of what an observer on the moon would actually see. (Disclaimer, I have little more than Layman's understanding of physics here, so the fact I'm attempting an answer at all is based on the leeway granted me by the "not strictly hard sci-fi" mentioned in the question)
* First, what I understand to be your only clearly defined minimum requirement:
1. The moon is not tidally locked (based on "The gas giant at times fills most of the moon's sky and at other times is absent". A tidally locked moon would not show such a change from the same location on the moon's surface, so that rules out a tidally locked moon)
As I understand it, tidal locking will happen, eventually, to anything orbiting anything else for long enough. I believe that's what Sean Raymond was referring to. However, just because it will happen, doesn't mean that it will have happened already at the time your story takes place, so I'd suggest you just assume that it hasn't happened yet, and move on.
* These I consider to be 'optional' requests, not strict requirements:
1. "as Earth-like as possible"
2. "on some nights the gas giant would appear lit up at night"
3. "the world (I read this as 'moon") will sometimes be cast into darkness as its view of its star is blocked by the gas giant"
4. "At other times a specific area on the world will be in darkness because it is facing away from the star (like Earth does) despite not being blocked by the gas giant."
5. "the world spins on its axis (in order to generate the required magnetosphere)."
6. "a way to frame this world's orbit that is plausible and also naturally occurring"
Based on those assumptions, here is my answer (Tidal locking previously addressed, so I won't restate that part here.):
The question implies the need for a "day", "night", "eclipse", "year", and "planet phases"(size, shape, position, brightness, of the gas giant in the sky).
So let's say the planet (not the moon) revolves around the star in 360 "Earthdays" (earthlike, but easier math than 365), so now we have the length of the "year".
Now lets say the moon revolves around the planet in 30 "Earthdays" (not far off of our own moon's 27-ish days, so again it's earthlike but a number for easier math)(for anyone that want's more hard science on this length of time, there are moons in our own solar system that orbit their planets or dwarf planets in anywhere from under under 8 hours up to more than 25 years, with several falling in the range of about 15-45 days, so I think 30 is very reasonable). So this is now the time frame for the "phases" of the gas giant in the sky.
And this revolution time will also account for part of the "eclipse" pattern. The gas giant will be in between the star and the planet for a few of these 30 "Earthdays", I'll pick 3 "Earthdays", again for the sake of easy math(though exactly how many would actually depend on many factors like the diameter of the star, the diameter of the gas giant, the gas giant's distance from the star, the moon's distance from the gas giant, the axial tilt of the moons orbit, etc.), and it could vary somewhat during the year due to any axial tilt on the moons orbit around the gas giant. So the normal eclipse has a duration of about 3 "Earthdays". (this is based on a gas giant that takes up about 36 degrees of angular diameter in the sky).
Now the phases themselves would be on a cycle similar to the moon here on earth, changing 'monthly' rather than daily or yearly. The eclipse would be like the "new moon" phase here on earth, and then for the next 13.5 "Earthdays"it would wax to 'full', and then for the 13.5 "Earthdays" after that it would wane again to the next eclipse.
That takes care of everything except day and night. Everything so far I've measured in "Earthdays", but what is a "day" on this moon? How does a day on this moon compare to a day on earth? Well, that's entirely up to the needs of the story, but all the possibilities fall in to 3 categories: 1. earthlike day; 2. longer day than earthlike (significantly more than 24 hours per rotation); 3. shorter day than earthlike (significantly less than 24 hours per rotation)
For an Earthlike day, the 3 day Eclipse would almost certainly be considered a very separate event from a normal "night", though the exact timing of it's start and finish could coincide with other nights, so that it's dark on the planet for more like 4 days instead of just 3 (daylight fades to a normal night, then just before dawn the eclipse starts, preventing that dawn, then 3 days later, as the eclipse is set to end, normal night falls, so even with the end of the eclipse, it's still night for the rest of the night), so in that sense it could be considered an extension of the night.
For a longer day than an earthlike day, the normal night cycle could last nearly as long, or even longer than, the eclipse. So the eclipse could simply extend one of the normal nights, or it could be an unusual night in the middle of what would have been daytime, depending on the timing and exact length selected for the daily rotation.
For a shorter day than earthlike, the eclipse would be much longer than a normal night, covering what the inhabitants might consider to be weeks or months, though it would still not take up any more of the actual year, just more day/night cycles per eclipse, with more day/night cycles in between eclipses as well. For example, if the day had about 4 hours of daylight and 4 hours of night, then the eclipse would last for 9 of those day/night cycles, instead of 3 for an earthlike day, and there would be 81 day/night cycles in between eclipses, instead of 27. And it would take the planet 40.5 days to wax full, and another 40.5 to wane again.
Using my numbers above, and an earthlike day length, there would be 12 eclipses per year, 30 days per eclipse cycle(month), each eclipse would last 3 days. Adjust as desired.
Everything else, related to climate and habitability of the planet, can be account for by adjusting the intensity of the star and the atmospheric composition (greenhouse gasses, etc.) and such as needed to get the tropical climate desired without any significant hard science requirements getting in the way.
(keep in mind that the exact numbers I use are partly arbitrary, and partly for convenience with math, and partly based on the information from the question, and are only for purposes of providing an example of what could happen, so they can, and probably should be, changed and adjusted as desired by the OP when applied to the actual story)
] |
[Question]
[
What happens to small pieces of debris left floating around inside a derelict space station?
My space station had 100 people aboard, and due to sabotage, it decompressed and was abandoned. Inside, there are thousands of small items, like screws, papers, tools, usb memory sticks, forks, and so on.
Movies usually show these hanging around in the air, but what would really happen to them over years and decades? Would any kind of rotation of the station produce centrifigual forces that would move all the debris to the walls? Would static charges cause them to clump together? Would frictional losses from collisions mean everything comes to rest randomly distributed against the walls?
When the atmosphere was lost, it happened reasonably slowly by an irreversible evacuation of the air through the main air circulation system until it reached total vacuum. My scenario has no artificial gravity, so items would usually be secured, but the evacuation occurred during a riot and there were minor explosions, damage, and panic so it was quite messy inside.
50 years later I wonder what the inside looks like.
Obviously I'm looking for realistic plausible answers here.
[Answer]
Things would slowly clump together or come to rest near a wall. Anything moving slowly will hit a wall or hit another object.
Unless the walls and objects are hard sided (like pool balls), they will lose more than a little energy every time they hit something. Eventually, the object will lose the energy to move after a collision. This will place them near something.
If passages are narrow, that location will likely be a wall. If it is a wide open space, there will likely be several clumps.
Also, any hits against the station will move the station faster than they move the objects inside it. I don't know for certain but I believe that a station with a wide cross section will face fairly random accelerations from micro impacts. Also, solar winds will cause regular accelerations. the accelerations will not be from a constant direction (unless solar tracking is still active in the solar panels). This will produce a cycle of accelerations that may bias the movement of objects in the station.
[Answer]
The inelastic part in any collision (call it friction, if you like) will decelerate any moving object in a very short time (hours or days, maximum). Below a certain collision speed, objects will stick to the walls due to van der Waals forces.
[Answer]
It depends on the motion, if any, of the station after it's abandoned; it won't take long before momentum loses in collisions will get all the objects moving in more or less the same direction and relatively "at rest", mostly on the walls but with some material in midair too. However once you get any new motion, say the "bump" from a docking salvage ship the equilibrium is broken and everything is thrown around afresh and could end up anywhere.
That assumes the station wasn't spinning at all, otherwise everything ends up on the "floor", that being the areas farthest from the axis of rotation. Even a very little spin caused by uncorrected recoil from evacuation ships would shift things slowly outwards over time. Again a salvage vessel docking will upset the settled material, especially if it corrects the spin in the process of docking.
Water is going to be an interesting factor, if enough of it is thrown around in the panic, either from burst pipes or as blood, it may well seal the hull when it freezes and freeze areas of material into solid rock-hard dirty ice chunks as well as allow you to have frozen atmosphere that didn't escape leaving patches of frozen oxygen etc... that will sublime on contact with anything above about 90 Kelvin.
Depending how long it takes to evacuate and freeze down once people leave and power fails you're looking at rotten stores as well as the potential blood and gore. That's going to leave shall we say organic stains in many areas.
] |
[Question]
[
I was rereading *The Restaurant at the End of the Universe*, the sequel to *The Hitchhiker's Guide to the Galaxy*, and I came across an interesting passage:
>
> Flare riding is one of the most exotic and exhilarating sports in existence, and those who can dare and afford to do it are among the most lionized men in the Galaxy.
>
>
> . . .
>
>
> This sport is made possible by the star ship's heat-sink, a mass of some two thousand billion tons and is contained within a black hole mounted in an electromagnetic field situated halfway along the length of the ship. This heat-sink enables the craft to be maneuvered to within a few miles of a yellow sun, there to catch and ride the solar flares that burst out from its surface.
>
>
>
Okay, so I'm calling Douglas Adams out on that one, but then again, nobody ever said that the books are scientifically plausible. I, however, would like to know if it's possible for us humans to do something similar, i.e. "surfing" solar flares, with our current technology or realistic technology that could be developed in the near future, or about 50 years from now.
Can we "surf" the Sun by using some sort of craft (perhaps modeled on a solar sail) to "ride" solar flares, coronal mass ejections, or something similar? If not, what are the major obstacles to doing so.
[Answer]
# Sounds awesome, let's try it
First off, let's talk about what a solar flare is putting out. According to [Wikipedia](https://en.wikipedia.org/wiki/Solar_flare), you are getting somewhere in the 1e20 to 1e25 J of EM radiation followed by charged particles moving at near the speed of light. Since either of these things would be deadly to you, let's assume that we want to surf the EM radiation, leaving the charged particles behind us.
# What are we riding?
First, here is the worst graphic I've ever pirated from a NASA website:
[](https://i.stack.imgur.com/DauTm.gif)
Despite being nearly illegible, we can see that we get peak flux in the ~1kEv X-ray range, which corresponds to about 1nm radiation. Conveniently, 0.1 to 0.8 nm X-rays are used to [classify](https://en.wikipedia.org/wiki/Solar_flare#Classification) solar flares. The biggest (and therefore the best, and don't I deserve the best?) flares would give us over 1e-4 watts per square meter. This is measured at Earth orbit, 1.50e11 meters. We'd start surfing at the Sun's corona at maybe 5e9 m from the sun. Multiply this ratio squared to get our observed power flux:
$$1\times10^{-4} \text{W/m}^2\left(\frac{1.5\times10^{11} \text{ m}}{5.0\times10^{9} \text{ m}}\right)^2 = 0.09 \text{W/m}^2$$ So let's say our max solar flare flux is an even $0.1 \text{W/m}^2$ while minimum is 1e-4.
# How to ride an X-ray
The best way to catch X-rays is to use a mirror, like the one on *Suzaku*, a former X-ray telescope satellite. The heavy metal coated [foil mirrors](https://universe.gsfc.nasa.gov/xrays/MirrorLab/xoptics.html) work by deflecting x-rays at shallow angles of incidence. The [*Suzaku* satellite](https://imagine.gsfc.nasa.gov/features/satellites/archive/astroe2_xray_telescope.html) mirrors are each about 40 cm in diameter and weight 19 kg.
# Stop right there
We've already discovered a problem. The area of a circle 40cm in diameter is 1.2 m$^2$. The ratio between energy of a photon, and its momentum is $c$, the speed of light: a photon as $c$ times more energy than it does momentum. So if we have an incident Type X solar flare, with 0.1 watts per meter squared, and every last shred of photon momentum is delivered to reflector, then we are delivering about 3e-10 kg m/s of momentum every second. Multiply by our area of 1.2 m$^2$ and divide that by 19kg of mass for the reflector, we can see that we are accelerating at about 1e-11 m/s$^2$. That's not going to get us anywhere.
# Ok, skip the X-rays, let's ride the charge particles
Well we've got another problem. Those 0.1 W/m$^2$ of x-rays aren't going to give you much momentum, but they sure will give you some cancer. Based on the radiation calculation parts from [this answer](https://worldbuilding.stackexchange.com/questions/71971/is-it-safe-to-orbit-hde-226868/72195#72195), we can assume that the human body is an excellent absorbent for nanometer/keV X-rays. Using the assumptions there, a 100kg person will absorb all the incident energy of about .5 m$^2$ of exposed surface, or about 0.05 J per 100 kg per second. This is equivalent to about 5 rem. That's not bad if that is your only dose, but that is per second.
In about 20 seconds, you will hit 100 rem for acute radiation poisoning; and the 1000 rem surely fatal dose will take about 3 minutes.
# What a downer
Looks like we're trapped between a rock and hard place. If we try to surf the x-rays, we won't get anywhere, and if we try to surf the charged particles, we'll get killed by x-rays. Looks like we'll have to settle for more Earthly [surfing pleasures](http://disney.wikia.com/wiki/TaleSpin).
[Answer]
**FIRST OF ALL, WHAT WE NEED IS POWER!!**
The reaction force that we require to surf is much higher than what the normal surfboard shape can get from the flares.
What I suggest is having large spherical shell at the bottom of surfboard fulfilling following aspects:
1. Much less mass for obvious reasons (Newton's third law).
2. Made up of Ferromagnetic material as we will be using magnetism.
3. Durable, after all it's solar flares we are riding.
**WORKING PRINCIPLE**
When solar flares hit earth, the charged particles accumulate at the poles giving rise to what we call *AURORA BOREALIS*. The reason behind it is the magnetic field of Earth. Similarly, our sphere is going to collect charged particles from surrounding, thus providing the required thrust.
[](https://i.stack.imgur.com/7Esx8.jpg)
For rest details consider [Kingledion's answer](https://worldbuilding.stackexchange.com/a/75082/2113) (right up there).
[Answer]
Not in any way that at all resembles "surfing", definitely not in the **near-future**.
The big challenge of doing anything near the Sun is thermal management. Right now it's a major achievement to just to get a probe within the orbit of Mercury. Making a probe that could directly interact with a flare in a meaningful way would need to get much closer and deal with far more heat even before you consider the flare itself.
Since large flares are the energy equivalent of 1 billion **megatons** of TNT I don't think we'll construct anything can survive it anytime soon.
] |
[Question]
[
One of the big problems by manned space exploration and colonization, that it's insanely expensive. Building a colony on other celestial bodies - since it's impractical to bring back the acquired resources to Earth - is surely a lossmaking enterprise, and therefore must be funded from the profit of other activities.
But it seems to me, that if there would be enough humans living on other bodies and in space habitats, it would become profitable to construct new, more safe and comfortable hab modules, develop new hydroponics technology, establish new mining settlements on new asteroids, build fast internet to the Jovian moons, etc... since those, who are already in space would be willing to pay for these services and goods.
Eventually, it could come to pass, that the majority of the investments would go into extraterrestrial investments, making Earth into a uncool rust belt, and encouraging even more people to migrate into space, making the colonization of the solar system into a self generating process?
**Where is this critical point? How much human presence in the space would be needed (How many humans, how much dollar worth infrastructure... ) in order to make supplying them a profitable undertaking?**
Conditions: Fission, fusion, and electric engines exist. (were used in early colonization efforts.) There is no significant antimatter technology, and no gravity manipulation. Nanostructure materials (like carbon nanotubes) are permitted, but nanobots not. The economic environment on the Earth is not bad.
Edit:
The cost of bringing them there doesn't matter, the scenario only has to be economical after the critical point is reached. So the question is not: Why would we need sending X men to Moon, Mars, Calisto, Titan...?, But how many many men should be there, to make the expanding and further developing their colonies into a good business?
[Answer]
## As a few others have pointed out, your assertion if insanely expensive may not be the case.
To make this more clear as in answering your question more literally, the initial business's I list here require few people and have high-value profits. This is based on revising the one and done OR disposable approach we currently have. So a few people, initially maintained by Earth Resources have to provide cheaper solutions to existing problems we have. That is a formula for immediate profit. There are a lot of these things and that means a lot of jobs in space, just the cleaning up part and then add on the repair and refueling. This phase basically pays for the next phase the colonization and industrialization of the Moon. The people doing the initial jobs need someplace to go and Earth is expensive, the moon is cheap. The money flows.
## Ways to be profitable.
The ability to refuel and repair existing space assets. What would one pay to be able to repair and upgrade Kepler, Hubble, etc?
The ability to cheaply build and implement new assets. How much would one pay to have new telescopes, satellites, etc; build in space then moved to the position?
The ability to provide Low Earth Orbit Habitats and provision them. How much would one pay to have large-scale habitats build in space and moved to low earth orbit, supply food and water grown by the Lunar Colony?
The ability to mitigate space hazards in Earth Space. How much would one pay to clean up the debris orbiting the Earth, to capture and utilize the Near Earth Orbit objects?
The ability to build, maintain and operate power sources for Earth. How much would one pay for the ability to build, maintain and operate a series of Solar Mirrors to provide clean cheap power to Earth ... as just one such method, X-Ray lasers and others would work as well.
The ability to Build and Launch exploration vehicles. How much does one pay to do this from Earth vs from an established Lunar Colony with infrastructure?
The list is rather long on ways to make money / be profitable in space.
**We just need to start thinking like a Space-faring species, rather than a Planetary Species.**
And what value would one put on being able to Reboot Humanity in the event of some self-inflicted devastation or some devastation from an external source? Just how much is that worth .....
To Expand ....
This is not about choosing Robots OR Humans. The state of the art in Robotic AI is not going to replace the flexibility, adaptability, or creativeness of Humans any time soon. So the relationship between Humans and Robots is cooperative existence. The number of Humans starts small and grows as the Job Opening / opportunities are created. Aside from the imperative of being profitable, the next greatest imperative is increasing Human presence. I want to see Blue Origin's goal of Millions of Humans working and living in Space to be a reality.
## Phase 1 “We need to start somewhere”
So a few good people …..
For 40+ Years we have spent a lot of money doing the same things. There is an opportunity now to do something … very differently. SpaceX, Blue Origin, and others are providing the means for things to change. Not directly at this time, but indirectly. Right now Boeing, SpaceX, and others are providing for transfer vehicles from Earth to the ISS and back.
What would these companies love more than anything else right now? New customers doing new things. Also known as growth. For new customers, as in Humans in space … remember the opportunity to change ….
**We have two very distinct and well-documented problems.**
Japan has attempted to address one of them. We have a highly polluted space where a lot of our assets orbit. This needs to be cleaned up.
Japan’s current plan is to burn it up by reentry. BUT is that really the most **economical** way to do this? A **lot** of **money was spent** on getting it up there.
Is all of it really of no value? Why can’t we take it and use the Sun, as in a Solar Furnace to process it to a reusable form? I mean that is mass that has **already been paid for** to get it up there. Ok, let's assume I can do this and am building a stockpile of Gold, Silver, Platinum, Copper, etc. It will obviously have some value and would be rather easy to return to Earth for sale. BUT its mass has already been paid for to get to space. Well, now we have resources that can be used in the 3rd phase.
## Phase 2 “I can repair, upgrade and refuel your Satellites”
So a lot more good people …….
Being in space and time on my hands, I can go to your Space Assets and do diagnostics, preventive maintenance, repairs, refuel, upgrades … you name it we will quote it and I am quite sure it will be significantly cheaper and significantly faster than you building a brand new one, insurance vs loss at launch, potentials for dysfunction etc.
We will be there, we will guarantee our work. Need that Satellite moved to a new orbit? We will quote that. Have a set of experiments you want to run? We will quote that.
## Phase 3 “We can build it cheaper and faster in Space”
So a whole lot more people …...
Being in space and having the time, materials and facilities (see phase 1 and phase 2).
We can build your Satellite in space for you and deliver it to the desired orbit. We guarantee the price will be significantly cheaper than for you to build it on Earth and Launch it, with all of the attendant risk’s for failure. Remember we guarantee our work. It is even feasible we can build you two for the price of one, with the second being a backup/redundancy to the first one so you will not experience downtime, during our maintenance/upgrades.
### What does all of this achieve?
For SpaceX, Blue Origin, Boeing etc. they now have a customer that is NOT politically fickle or driven. They have regular schedules to deliver food, water, and customer-supplied parts, in greater quantities than currently available to them.
For 3D Printers looking for a need to fill. Well with the accumulated resources and more economical deliveries from Earth based on competition and increased frequencies, it will become more economical for us to fabricate the parts in space than to have them built and launched from Earth.
We have learned how to Live and Work in Space and established a Space Population.
We need to be independant of Earth Resources.
Well, now then SpaceX, Blue Origin, Boeing etc have had time to see this coming. We need to become independant from Earth Resources. The thing we will need most are Space Transfer Vehicles. The ability to move around from point x to point y. The ability to move mass from point x to point y. They should be able to supply these vehicles and if they do not then we can supply them ourselves.
So the next phase Colonize the Moon.
## Phase 4
Very little change in the number of Humans ...
Identify the easy picking resource of the Moon, focus on Water and Lava Tubes suitable for Human Habitation. Secondary any and all other resources that provide a source for materials currently supplied by Earth.
### Phase 5.a
Very little change in the number of Humans ...
Select a Lava Tube for Habitation. Seal it, pressurize it, establish a power supply, establish a water source, both at the habitat and the source. Bad habits are hard to break, so we must keep this in mind. Use the water and other resources to establish a viable atmosphere. Establish a Life Cycle system. One might look at current Fish Farms. The ideal system will at a minimum provide food, filter the water, and prep waste for use in more traditional farm products. Ideally, in the end, it can do recycling of the atmosphere (plants … whatever).
### Phase 5.b
Very little change in the number of Humans ...
Establish manufacturing systems and supplies. This means all the equipment and resources to produce the things used in Phase 1 through Phase 3 and the Space Transfer Vehicles.
### Phase 5.c
Very little change in the number of Humans ...
It is imperative that any bad habits as using the Water etc for things that have very little to nothing to do with supporting Life need to be ended. I will go so far as to say creating a Space Vehicle that can be used to scoop the upper atmosphere of Earth (later the other planets/moons) for required gas’s. The focus needs to be on how to produce these gases from existing resources, other than water.
At the conclusion of **Phase 5** we will have a model of how to **Live, Work and be self sufficient on the Moon.** This model can be used by **any group** to expand the Human Population on the Moon.
## Phase 6
So a Human Civilization an explosion in the numbers of Humans in Space ……
Go Crazy
Build Survey Ships capable of building a data repository of the objects in OUR Solar System … all the way out to the Heliosheath / Heliopause.
Build Colonization Ships to be used to 1 shot colonize planets, moons, asteroids.
Build reservoirs of Water, from Comets … whatever.
## Transition Humans to a Space-faring Species from a Planetary Species shall continue.
[Answer]
The minimum? About ten. If they can research compounds and alloys that cannot be made in a gravity well, it might be possible to make your money back with just the research results.
Energy: harvesting He3 on the Moon would take a couple hundred people. Building large solar arrays to microwave the energy back to Earth would take up to 1000 (probably less) to build and position the arrays.
Manufacturing: Making things that cannot be made in a gravity well like alloys of compounds with very different specific densities, foam steel, flawless crystals: Unknown, it depends on how fragile and heavy the items are. If it not fragile at all, put it in a pod with a heat shield and aim for some place safe. If it is slightly fragile, put a parachute on it. If it is really delicate, you need something that can land gently; that might be expensive enough that you would want to send it back into space instead of build one use vehicles.
Another question is: how many people do you need to get into space before they say, "No."
[Answer]
>
> How much human presence in the space would be needed (How many humans, how much dollar worth infrastructure... ) in order to make supplying them a profitable undertaking?
>
>
>
In my opinion, never. The space infrastructure would need to be self-sustaining. It doesn't matter how many people are in space. It's never profitable to supply them from Earth. They need to be able to produce their own food, etc.
We can supply small colonies for scientific purposes. One can argue that the scientific value of those colonies outweighs their expense. But that scientific value doesn't scale up. Yes, more people could do more work, but the best work is the first work. It scales down from there.
There are similar problems with tourism, etc. The first purchasers produce the most revenue per capita. At scale, they lose more money.
Goods are even worse. Shipping goods from the Earth to space is simply not profitable. You'd be better off keeping the people on Earth. It may eventually be profitable to ship goods from space to Earth. For example, with sufficient automation, shipping goods or raw materials from the asteroid belt might make sense. Using solar energy and asteroid materials makes everything essentially free in terms of Earth resources. Landing them might be more expensive than building on Earth though.
The expensive part is lifting into Earth orbit. From there, we could use mostly space-based resources to ship to the rest of the solar system. Even using Earth-resources, lifting into orbit is the greater portion of the cost. It's actually cheaper in terms of energy to ship from the asteroid belt than from the surface of the Earth. It's just that we don't have the facilities in the asteroid belt to do that shipping.
We can transfer energy from space to Earth, but we are already complaining about global warming. Increasing the amount of energy sent to Earth would only make that worse. It might make more sense to direct energy away or better collect the energy that giant fusion plant (the Sun) is constantly sending us.
Knowledge can just justify a modest amount of transit from Earth to space, but the real thing that space has in abundance is, well, space. Once space is self-sustaining, people may spend Earth resources to get there.
I previously asked a [question](https://worldbuilding.stackexchange.com/q/3943/2113) about how much it would cost to set up asteroid mining versus just supplying from Earth. Unfortunately there still hasn't been anything that I'd consider an answer. Maybe it's just a hard question with too many unknowns. If there was an answer to that question, I would list it as the answer to this question as well.
That would be the point when space was self-sustaining. But that gets back to my original point. It's still not profitable to send stuff from Earth to space. It's only ever profitable to send people, at least at any scale.
[Answer]
One of the main reasons why getting things to and from space is this impractical gravity well we live in.
Yo ruled out antigravity, and for good reasons. But since you do allow nanostructure materials, you should be able to build a space elevator.
Once that is in place, your costs for lifting things out of the gravity well, and for making a safe re-entry, are next to nothing.
You also allow for fusion tech, so you get quasi-limitless power.
In my opinion that means you could have a post-scarcity scenario. This means, that the question of profit is no longer a delta-dollar-question, but much more humanistic. Or, in other words, 'profitable' can be anything you like it to be. It might even be "trading huge amounts of ugly and heavy gold for super-delicious mars strawberries".
But putting that aside: Others have described that producing things in zero (or low) gravity might be interesting. But also producing things in a non-corrosive (or non-existent) atmosphere might be interesting, too.
So, after effectively removing energy cost from your scenario, profitability is more or less guaranteed.
And how many people: Groups of up to 120 individuals, since apparently that is a rough number people generally feel comfortable with.
] |
[Question]
[
How scientifically plausible is this? A giant, self-aware fungal supercomputer made or evolved from something like the Blue Mountain honey fungus or maybe a slime mold of a similar size? Could something like this ever exist in nature as an example of distributed intelligence, or would it have to be created?
It has to explicitly be self-aware and just as intelligent as humans. The ability to modify its own genes to secrete chemicals that'll attract new prey is a bonus, but frankly I'll settle for a plain ol' giant mushroom supercomputer xP
[Answer]
If you're delving into the intelligence of mushrooms, you might want to take a look at some of Paul Stamets' work on the subject.
Distributed intelligence is likely your best bet. Mycelium works in concert and symbiotically so, there's a two routes I would go were I looking to create such a thing.
* **Symbiosis leads to hyper intelligence**
In this case, mushrooms or fungi attaches itself to another creature which has had an evolutionary push in the direction of tools, hands and language. The creature it is attached to may actually be less intelligent prior to the fungi becoming part of it. The fungi evolved in this way in order to spread more efficiently and create and environment more suited for itself. The host creature benefits by becoming smarter and being better able to survive, through such things as chemical secretion. The mushroom bit might be only part that serves for a higher functioning and brain-power, but this would solve the problem of mobility and the evolution of hands. There are animals upon which fungi grows. A sloth-like creature might be a good start. If the fungi rewires it enough, it may become faster and when it is totally taken over, looks less like a sloth and more like a mushroom.
* **Networking Intelligence** In this version of things, the more of them there are in an area, the smarter they are. Mycelium is highly adaptive. This intelligence has helped them to survive more efficiently. While they might be as smart as humans or smarter, they would not necessarily communicate using sounds and words. Their entire language can be chemically based. Each bit of them performs a specific function of thinking in the colony, though they all share knowledge. In this case, one mushroom may actually be mobile, while the others just hang out in the soil.
[Answer]
My concern would be the energy required to maintain sentience. The human brain is a calorie hog, taking 20% of the body's energy supply. Fungi, making a living by decomposing stuff, survive on much less energy than any mammal, and they don't have access to the 25 watts or so that the human brain needs. (This, by the way, is an incredible adaption. Compare this to the rating of your computer)
Distributed intelligence makes thinking slow. Chemical signals are passed relatively slowly (compared with electrical ones). A large brain is a slow brain, but this at least lowers the power requirements. The fungus might think like Pratchets A'tuin, with each idea taking days to form.
Of course these problems can be handwaved away. But a being that thinks and experiences 100 times slower than we do. [Among Earth animals](http://www.independent.co.uk/news/science/q-why-is-it-so-hard-to-swat-a-housefly-a-it-sees-you-coming-in-slow-motion-8818124.html), those with small, fast brains: like a housefly, can process visual information 7 times faster than we can. Where as large brains, in a low energy configuation, (the leatherback turtle) are three times slower.
Could this fungus evolve-- tricky. It would depend on the environment. Intelligence would normally evolve as the end of an arms-race, or perhaps from sexual selection. Humans evolved intelligence perhaps because they there was a need to be highly mobile and adaptable -- hard to fit this model to a fungus.
The fungus needs to be able to act in someway. I suggest animal symbiots. The fungus thinks up the strategy. The symbiotic animals carry it out. So to hunt the bisonolopes that live in the forest, the fungus thinks up "throw sharp stones at them", the symbiots do the sharpening and throwing. The carry the spoils back to the nest. (think of a [leaf-cutter ant](https://en.wikipedia.org/wiki/Ant%E2%80%93fungus_mutualism) as a model)
[Answer]
Sure why not?
All you need for intelligence is communication pathways and signal discrimination.
That's a computer science AI perspective though. From a evolutionary biology point of view the question is, why does a fungus have hard intellectual problems to solve? It wouldn't bother getting smart unless it needed to. If you want to satisfy the biologists the fungus needs to benefit from this calorie consuming intelligence in some way.
] |
[Question]
[
My story (same world as [here](https://worldbuilding.stackexchange.com/questions/39579/can-you-help-me-design-a-realistic-climate-map-for-my-world-alternate-earth)) take place in a future Earth between 3 and 5 million years in the future. **What kind of artifacts, if any, would civilizations from this era find from the now extinct humans? What tangible consequences would the [Anthropocene](https://en.wikipedia.org/wiki/Anthropocene) have on their life and societies?**
*Random ideas on this topic:*
* Ceramic will last indefinitely because of its molecular stability, similar to fossils in composition. Aluminum and stainless steel in tools (in cookware for example) will survive and so will (probably) plastic: the discovery of readymade tools could bring a sudden technological development and/or the emergence of a religious conscience to explain their presence.
* I expect plastic to be widespread, sometimes conserved in rock as a somewhat recognizable item and other times degraded to invisible dust (maybe even part of some newly evolved food chain?)
* Stone crafts and sculptures, like mount Rushmore, have a pretty good chance to survive the ages, even if terribly distorted by erosion and ice ages.
* In dry climates metals corrode but wood have a chance of being preserved.
* Streets and underground tunnels will collapse and they will probable became riverbeds in temperate climates. When the cities will inevitably crumble, mud and silt from these rivers will bury objects, tires, cars and even entire houses. In time mud will become rock and things will be preserved inside until maybe a river or a glacier will dig a canyon exposing the ancient buildings and relics.
* Structures in steel and reinforced concrete will crumble, be grinded and compressed under new geological strata, leaving this probably reddish layer rich in excellent quality metals (could be reused? Mined?).
Any other ideas?
EDIT: Rephrased the question to address a more specific topic;
DISCLAIMER: this question is different from [What would be left of a civilization founded in dinosaur times?](https://worldbuilding.stackexchange.com/questions/12564/what-would-be-left-of-a-civilization-founded-in-dinosaur-times) That question is about an imaginary society in the past with no interest on its influence on today human society, while my question is about OUR OWN society and how it will influence future civilizations. Things like the Pyramids or Mt. Rushmore can survive a few million years, so they are relevant artifact for the topic i'm talking about.
ALSO, 65 million years and ~4 million years is a really big time difference by all terms. [Four geological periods](https://en.wikipedia.org/wiki/Period_(geology)) have followed since 65 mya and [an entire geological era has passed](https://en.wikipedia.org/wiki/Mesozoic). Tectonics really plays a crucial role when talking about +65 millions of years; huge impact craters can be eroded, mountains rise and wear away, oceans are formed or vanish. Complex processes like the transformation of biomass in hydrocarbons can take place. My question revolves around a significant smaller time scale. The time frame i'm talking about would be entirely paced inside [our own geological period](https://en.wikipedia.org/wiki/Quaternary). A difference of just a few millions years is important when talking of radioactive decay and the legacy of other human-related activities.
[Answer]
You need to be aware that four million years is significant in geological time. Ground level is not constant. In some places the ground is rising and in others it us falling. Human artifacts that are forced up will be weathered away over mere tens of millennia. Where ground level falls they will be buried and possibly preserved, but the burial may be a lot deeper than you expect. Almost everywhere, deeper than primitives will dig.
Consider London, which is sinking. The streets of Roman London are three to six meters below today's. Say two meters per millennium. Over a few million years that adds up to many kilometers.
So four million years hence there will be very little if any of our civilization visible at ground level. A pre-industrial people probably will not detect any sign that they are not the first people. Only when they start deep mining on an industrial scale and start a scientific study of geology will they notice our remains. The very occasional finds of technological fossils will probably be attributed to ancient gods or mythical civilisations like our Atlantis lying in the relatively recent past.
I expect initial discoveries will be hugely disputed, just as the existence of deep time, geological movement and drifting continents were fiercely disputed well into the 20th century.
Will their attainment of our levels of technology by hastened by the eventual mapping out of fossil cities? I doubt that anything would be well enough preserved to significantly advance their development. At this remove of time it would be far easier to see what we built, than how we built it.
[Answer]
A satellite high up in the atmosphere in a geostationary or highly elliptical orbit has the potential to stay in space for thousands, or even millions of years.
] |
[Question]
[
Assuming an average, fully developed adult man, **what sort of changes could be made to his genome that would have a noticeable effect on his mind or body**? To the best of our current scientific knowledge, that is. I know we don't know what a lot of genes are for.
To be specific, I want to know if you could change the physicality of a person, as in, their strength, stamina, and metabolism, and wether or not you can change a person's personality, most importantly their focus, or at least their urges.
Other information that I know:
* Most genes responsible for features are only relevant during the development of those features, and changing them post-development would have no effect of the person who had the change. For example, changing genes for bone structure would have no effect on somebody with developed bones. Their children might show a change, though.
* Editing the genome of an adult is difficult due to the number of cells that have to be edited. Assume this has been taken care of.
BONUS POINTS (You don't have to) IF
* You can link to a research paper describing a gene and its effect on an adult.
Also, does this question qualify for the [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") tag?
[Answer]
[Gene therapy](https://en.wikipedia.org/wiki/Gene_therapy) is a real thing, and you can read about the various changes that are contemplated and realistic enough to research.
It has trouble actually *working* in a living body when it seems obvious (replace a defective copy of a protein making gene) and seems ok in a cell culture. So doing something like that in a large scale is probably far more difficult to get to work.
Assuming advanced tech *can* replace genes in living cells that are part of tissue and not otherwise damage things, what can happen? Consider what happens if you update code for a liver enzyme, and it's not a liver cell: nothing! Not all genes are used in all cells.
What happens if you change the code that controls limb growth during development? Nothing! That program is run as an embryo and never again. It would affect his children.
Now some "layout" is done during healing. If you change the code for growing skin— how the [dermis](https://en.wikipedia.org/wiki/Dermis) lays out all the different cell types to produce connective tissue, blood vescles, glands, and skin organs, then to the extent that the body can regrow missing skin, it will produce the new design. Routine replacing of the epithelial cells will only involve the code for producing those cells, not any different kind of cell or layout.
Changing behavior and urges: look at hormone production. What can be done with drugs? Any drug's effect can be produced directly with reprogramming the cells. Change the behavior of dopamine receptors by jamming them open? Just alter them instead, or just produce the same drug directly in the cells!
[Answer]
Your entire body cycles through cells many times throughout your entire life. If you completely rewrote your DNA, then changes would gradually appear as cells replaced themselves.
Your stomach lining, for example, completely cycles every three days or so. Change that, and you might be able to digest things differently.
Could you change the rate of change? You might get effects to appear faster.
Every time your DNA replicates, the end pieces (telomers) don't and the copy is a tiny bit shorter. That adds up over the years. If you replace your DNA with long fresh strands, then you've just become immune to old-age.
[Answer]
Continuing with Omniwombat's theme that *most* (all, except brain cells in cerebral cortex, they say) of your body cells are replaced with newer ones, some of the most visible changes you could produce with editing your dna are:
# Skin
Since skin cells are replaced every 4 weeks ([reference](http://www.dailymail.co.uk/health/article-1219995/Believe-lungs-weeks-old--taste-buds-just-days-So-old-rest-body.html)), any change related to the color, thickness and texture of your skin would be visible after a month or so at most. I don't know if you can get away (survive) with adding snake-like scales or turtle-like body armor to yourself, but you can get away with making yourself hairless (you won't die *directly* of hair loss, but there might be indirect implications).
# Endocrine System
Hormones control a *lot* of our behavior and internal functionality. Twerking with your pituitary, adrenal and thyroid glands to increase/decrease the release of their hormones would produce a marked difference in your behavior and body shape/functionality.
] |
[Question]
[
Related: [What if the social contract was literal?](https://worldbuilding.stackexchange.com/questions/12304/what-if-the-social-contract-was-literal)
## Backstory (Optional)
In *Levithania* it is recognized that, until 18, a child has no rights of themselves, being owned by the parents. Parents have a duty to raise their children responsibly, and may allow their children to make decisions, but the state does not recognize them as having any rights. If something happens to a child, it is the parents that sue, not the child.
In particular, a child, of themselves, may sign no contract. If a child, for example, wants to get a job, the parents would sign a contract with the employer whereby they agree that the child will work there if they give the child money (which is implicitly owned by the parents) (most parents, being reasonable, make such decisions based off what the child wants).
This all changes though when the child turns 18. The day before every child turns 18, they go to the signing place, at the borders of Levithania. At the moment they turn 18, any rights their parents where holding on their behalf are transferred to the child, and any contracts the parents sign no longer apply to the child (although the child may choose to renew them).
In particular, the child is no longer bound by the laws of Levithania. They are a free person, and temporarily, considered a foreigner. A pair of soldiers stand by them, now in a [State of Nature](https://en.wikipedia.org/wiki/State_of_nature).
They are now officially a person.
A government official brings in a copy of the Levithania constitution, known as the "Contract for the Agreement of Cooperation between Levithanians" or the Contract for short. At school as a child, they took a class on this document, so they understand it fully.
The person now can decide for themselves whether they want to be bound by the laws of Levithania. If they accept, they will read the contract aloud, and then sign it. They are now bound for life to follow this contract (unless some condition specified allows it to be terminated (for example, a legal body given proper authority by the Contract may pass a law allowing citizens to terminate the Contract if they move away from Levithania)), and in particular it is considered just for laws to be enforced against them. They additionally gain the rights and privileges listed in the contract. They are a Levithania. Then they have a celebration usually.
Now, for anyone to truly have chosen to be a Levithania, and the Contract to hold any manner justice, the person is also given the choice to not sign the document, and to remain in the State of nature. This is the ultimate check and balance on the government, the ability of new citizens to not agree to Levithanian law. If this is done, the soldiers escort the foreigner off of Levithania, with any possessions the parents give them, and exile them. They may only return if they go through immigration, which involves a similar ceremony.
The question is, where are they exiled?
**The End**
---
## The Question
How do you exile someone, given that most of the world is already claimed for various countries (think current day Earth). Putting them in another country would violate the rights they have over themselves, since that other country would presumably force them to follow their laws (if the person agrees with that, its fine, but a large number of non-signers want to be anarchists, and won't agree to any laws.)
What can be done with those who decline the rules of society?
Keep in mind that, if the government is currently being very bad, you may have a large number of non-signers. Therefore, we want this to be cheap.
(Backstory FAQ: What happens if you pass a new law? There is a law making process. You don't re-sign for each new law, since you agreed to the law making process. What if you break a law? The Contract specifies that. Probably built-in to each law. Probably fines or jail or what have you. Branches of government can also punish each other, in accordance with the contract. If the government breaks the Contract extremely enough, the people are morally allowed to rebel or not recognize the government, which means the government won't break it too badly. What makes this different from what we have know? It's mostly philosophical, but still in an important way. It gives the government [Legitimacy](https://en.wikipedia.org/wiki/Legitimacy_(political)). It's a different mindset when everyone is a signer of the constitution. It's sort of part of their national identity.)
[Answer]
There's a philosophical landmine hiding in that constitution, in the phrase "Putting them in another country would violate the rights they have over themselves, since that other country would presumably force them to follow their laws" that you added in the edit. I do believe it is the fundamental landmine of Levithania. By this wording, if someone refused to sign, they still have rights. They have a right not to have a law forced upon them. Thus, this shows that the Levithanian constitution includes a framework for how to deal with non-Levithanian individuals, those who had not signed a contract.
This is a non-trivial detail because it shows that Levithania does care about non-citizens, such as those living in foreign nations. They are not isolated. They *care* what happens to this non-signatory.
The first natural consequence is that Levithania will not assume ultimate responsibility for a non-signatory. If they did, other nations would easily abuse this to force Levithania into undesirable situations if a particular anarchist non-signatory wanted to help the other nations do so by refusing to submit to any law until certain constraints are met while simultaneously putting himself or herself in a position that prevented their "return to nature." For example, if Levithania were to rely on sending someone out to international waters, and a foreign nation had set up an embargo preventing the deportation of non-signatories, Levithania would find its laws put it in a mighty disadvantaged place.
So we know they care about the non-signatories, but their caring is not absolute. This is a very human position for a country to find themselves in. No black or white, but shades of grey. The humanity of this position helps mollify the stark line between citizen and non-citizen, and permits us to consider some very real solutions done in the past by nations of the world alongside some that have been considered by philosophers:
* The most extreme solution is to let them go. Levithania guaranteed they could return to a "State of nature." They guaranteed nothing about whether nature would be friendly or hostile when they got out. They might designate several DMZ's along their boarder where they ensure other nations will not claim the land. The non-signatories may be dumped into these DMZs, to fend alone as part of nature.
* They may be permitted to live in Levithania as a non-citizen. Islam has explicit instructions for ways to deal with non-Muslims in a Islamic state. They actually have three classes of such non-Muslims, the most applicable of which is the Zimmis. Zimmis are non-Muslims living in an Islamic state who pay a tax and accept Islamic law while they reside in the Islamic state. They have many limitations as to what they can and cannot do, but they are [typically] permitted to leave at any time.
* Levithania may rely on diplomacy to ensure nearby countries maintain refugee camps for non-signatories. This may not be sufficient for the most staunch of anarchists, but it may be enough to show that Levithania "cares."
As a final solution to this conundrum, I'd like to explore a path which is not part of any existing sovereign policy or philosophical stance. What if the Levithanian constitution permitted one to write their own contract? Obviously we will have to apply limits to this, but what limits could one choose? What if the two soldiers are not just any soldiers, but Vanguards of Levithania with the sovereign power to accept any signed document as a declaration of citizenship *if they feel it is best for Levithania.* These soldiers are not only trained in physical combat, but in law and philosophy and ethics. They serve as a High Court of Levithania, presiding over the acceptance of citizenship with binding authority.
Anyone who does not wish to sign the Levithania contract in its exact current form today, is free to write up a new contract, and attempt to convince the two soldiers that blessing this new contract serves Levithania. Many interactions would spawn from this. Anarchists would seek to provide a small or nonexistant contract, and the Soldiers may refuse it. Individuals who have issues with individual parts of the law may explicitly write out changes, and seek to have the Soldiers bless these changes as in Levithania's interests. Some great minds may even get away with sweeping changes, because Levithania benefits so much from their mind remaining in the country rather than going abroad.
Intriguingly the same approach would work for foreigners entering the country seeking citizenship. They should feel free to ask the Soldiers to accept any document they please as a document of citizenship, and it would be up to the Soldiers to decide if, at that moment in time, that alternate document is in Levithania's best interests.
[Answer]
Oddly enough, something similar was explored by Heinlein in the book "Starship Troopers". Only people who not only fully accepted and internalized the Federation's philosophical foundations, but who actually voluntarily enrolled in and completed a term of service in the "Federal Services" were granted full rights, including the right to vote and seek office. Jerry Pournelle's "Co-Dominium" cycle of stories is also set in a world where welfare islands house "Citizens", while full rights are granted to "Taxpayers" who have income and contribute to society.
In each case, rather than trying to eject the people who do not have full rights and responsibilities, the State allows them to continue to live and work, but with reduced rights and responsibilities. In the universe of Starship Troopers, they actually have almost all the rights of current day citizens in a Western nation (they obviously own property, can run business and can even become quite wealthy, like Johnny Rico's family is), but do not participate in the legislature or judiciary, and cannot vote. In many respects, the large number of people who don't vote in present day Western nations have already accepted that part of the bargain.
In Pournelle's conception, the non productive are housed in essentially walled cities and pacified with welfare and drugs, kept separate from the "Taxpayers" who do the work. This is much less successful, since "Citizens" outnumber "Taxpayers" by a wide margin, and the political class manipulates the "Citizens" for their own ends as well. Both Citizen and Taxpayer class Americans in the Co Dominium universe are generally controlled by a sort of permanent oligarchy of politicians and crony capitalists.
So long as your State is willing to codify and accept some sort of "resident alien" or "non citizen resident" status in the nation (but obviously not the body politic), then people who refuse to sign the social contract may choose to leave the nation, or to re-enter with only the clothes on their back and whatever their parents gifted them in the second category of residency.
[Answer]
Well, your question "How do you exile someone, given that most of the world is already claimed for various countries (think current day Earth). Putting them in another country would violate the rights they have over themselves, since that other country would presumably force them to follow their laws" is simple: you can't. At least, not without a good deal of mental gyrations and weasel-wording.
Having granted every person an absolute right to personal self-determination, Levithiana can no more expel a person without cause than an EU country can grant extradition of an accused murderer to Texas. Unless they're willing to take "12-mile limit and a rowboat" solution, which you seem to have some difficulties with.
There's your problem: "Putting them in another country would violate the rights they have over themselves." Until and unless Levithiana can convince some or most of the other countries of the world to adopt their value system, it will be hopelessly at odds with them. Furthermore, it seems that immigrants to Levithiana will be few and far between. Apparently there is no such category as "non-citizen resident" which is generally applied to would-be immigrants who reside in the country before naturalization. If there were such a category, your would-be anarchists would fit neatly. Would-be immigrants are not citizens, so they cannot sign The Contract, yet clearly they must be held accountable for their behavior. This implies the existence of a coercive legal system with the power to impose penalties on the unwilling. The alternative to this is the Draconian penalty of deportation for *any* offense, and this would, of course, violate the same inherent, absolute right which gives you trouble with non-signers.
By this reasoning no other government not operating by Levithania's philosophy is legitimate. Yet "They are a free person, and temporarily, considered a foreigner." You have confused the general, diffuse concept of "foreigner" with the specific "citizen of a foreign country".
[Answer]
Put them in a region that is not under any government's control.
In the modern world put them in international waters in a small boat. They can then go to any country they want, or start a new one.
There are other questions in the system.
What if parents can't adequately control the child. Who is punished for the child's crime?
If the laws or constitution is changed does everyone have to sign again?
Is it coercion to say accept our laws or be exiled from every one and everything you ever knew?
Who is in charge of interpreting the grey areas that are not explicit in the constitution.
Does everyone have to sign the same constitution?
[Answer]
Simply explained the laws of the surrounding regions and let them choose one and then deport them to the land of their choice. Since they get to choose where they want to go no law has been broken.
] |
[Question]
[
NASA has received a new employee: a dragon! His name is Firewing and he's there to help NASA with its missions. He's not an astronaut himself, mainly because of the logistical issues of launching a dragon into space (and because NASA knows that if they did that they might as well close up shop because nothing they could do would be more awesome than launching a dragon into space). He's also not some genius scientist so he won't be squeezing himself into the LCC to oversee launches or crunching numbers somewhere else at the KSC. Instead, Firewing's going to use his superior physical abilities to help NASA. He's got the following abilities:
* He's about as big as Smaug.
* He can fly as fast as the Space Shuttle and can keep this up for quite a while.
* His flight ceiling is 37,000 ft, the equivalent of [Rüppell's vulture](https://en.wikipedia.org/wiki/R%C3%BCppell's_vulture).
* He's capable of carrying the equivalent of a fully loaded (fueled + cargo, though not with any ETs) Space Shuttle without a loss of speed. Any higher cargo load will dramatically influence his speed.
* He can grab onto spacecraft without damaging them and knows how to catch something that's falling without having it rip in half due to the forces involved. Meanwhile, he's capable of picking up people without the threat of accidentally crushing them.
* He can be exposed to the heat, light and gas emissions from any engine without suffering any negative effects (though he'd rather not have physical contact with any of those for a prolonged amount of time).
* NASA developed a communication device that fits over his head which allows two-way communication between him and the LCC (or whatever the device's dialed to).
* He understands the briefings that NASA give him and the directions he receives mid-mission. Additionally, he's intelligent enough to improvise on the fly in case things go wrong.
* His fire is about as hot and long as the flame from a Space Shuttle External Tank. Note that this does not generate backwards thrust.
* His diet and accommodations are taken care of.
Note that Firewing would be willing to help with testing things and running trials instead of actual space missions, but he is very much opposed to serving as a guinea pig with tests run on him and would rather not serve PR purposes (but filming him while he's working is fine).
As you can see, Firewing is not capable of launching a Space Shuttle (or its equivalent) on his own, but he might be able to do other things. What kind of jobs would be be best suited for?
[Answer]
Firewing could be useful for NASA with assisted rocket launches. Even just lifting the space shuttle a few miles off the surface of the planet could be useful to decrease the cost of the launch:
>
> Fortunately, due to the exponential nature of the rocket equation, providing even a small amount of the velocity to LEO by other means has the potential of greatly reducing the cost of getting to orbit.
>
>
>
See [this](https://en.wikipedia.org/wiki/Non-rocket_spacelaunch) article.
[Answer]
**Splashdown recovery!**
Currently, NASA does not have any manned spacecraft in use (astronauts use the Russia Soyuz capsules). However, in the past, NASA capsules used a [splashdown landing](https://en.wikipedia.org/wiki/Splashdown) in the ocean. A helicopter would come to bring back the astronauts (and then the capsule) to an aircraft carrier dispatched for the purpose.
The method has also been used by unmanned spacecraft, and will be used in the future. I therefore propose using Firewing as a recovery tool. It seems like he can fly long distances, so unlike the helicopters, range may not be an issue. Perhaps an aircraft carrier is completely unnecessary. This then greatly reduces the cost of splashdown recovery.
Also, riding back in a capsule in a dragon's claws is pretty stylish, and reminiscent of Frodo and Sam being rescued by the Eagles from Mount Doom. . .
[Answer]
Firewing would be great for training. Instead of expensive machines like planes and manpower, Firewing would be able to take the astronauts high enough for them to experience whatever they need to experience to be qualified as astronauts (I am not an expert in that field, but with some research you should find out the specific training program a where a dragon could substitute expensive machinery).
Then: machinery testing. Many spaceship parts should be tried for heat resistance and flamability, like the engines. Firewing would be a great for that job. He could also help with heavy transportations.
Lastly, he could provide some sort of security help during the launches. He couldn't jettison the shuttles into space, but he might fly alongside it and should anything go wrong stabilize the trajectory, or influence the speed, or worse case scenario catch it and bring it back to Earth. Safety measures.
[Answer]
We all know the [Space Shuttle Challenger disaster](https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disaster), and we know that the astronauts within the space shuttle have survived the explosion, but the violent impact with the sea surface has caused their deaths, so if a well trained huge dragon like Firewing was there, he would certainly flew up and saved those poor astronauts.
>
> several crew members are known to have survived the initial breakup of
> the spacecraft. The shuttle had no escape system, and the impact of
> the crew compartment with the ocean surface was too violent to be
> survivable.
>
>
>
[Answer]
There are several things NASA could do with Firewing!
**1.** A project similiar to the [Grasshopper](https://en.wikipedia.org/wiki/Grasshopper_(rocket))(SpaceX) would be easier to achieve. With less precise Calculations and testing necessary since all they would need to achieve on their own would be getting the rocket safely beneath his flight ceiling and he could just catch it and bring down to the ground without damage.
**2.** Maybe Firewing could also serve as a source of propellant? You did not specify how his flame breath works, so we can just assume his body naturally produces rocket fuel and ignites it in his throat/mouth. With a bit of training he could expel the fuel without igniting it.
**3.** As stated in other answers as well, Firewing could be used to fly next to any starting rocket acting as a fail-safe if there are complications he could solve them on his own by acting fast if they are no brainers or wait for instructions from LCC.
] |
[Question]
[
**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
---
This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help).
Closed 8 years ago.
[Improve this question](/posts/31023/edit)
**Would they make their presence and awareness of the game-situation known, or would they keep their simulated heads down and continue poking undetected, hoping that some automated bug-cleaner doesn't wipe them out?**
Detailed Context:
Appears to be a historical simulation of some sort, centered around 2015-2016 C.E., perhaps better known as the present-day world. The game/simulation seems precise/detailed to the atomic (or perhaps subatomic level), and is an open-world, at least as far as Earth's surface is concerned. The game-aware group appear to be exclusively non-player-characters, or NPCs, (at least none have any memory of having been possessed!).
It took some effort to get here, but the group of similarly awaken NPCs are able to identify player-characters (PCs) by sight, as they now (did not have this ability before) can see a red aura or glow around the PCs. The group haven't exactly done a scientific survey, but the PCs seem to comprise about 0.5% of the population, with some presence in all social classes, but with a marked predisposition towards the ultra-rich and famous.
It's hard to be exactly sure, but the 'make-PCs glow red' achievement strongly suggests that the group's methods so far gave them access to some run-time debugger or perhaps a limited section of the source code. The PCs seem unaware of the situation.
It seems likely that the "source" civilization is probably a descendant of humanity, with generally higher technology levels than the present (just running this Earth sim would tax in-sim technology to the breaking point), and uncertain motives in running this game/simulation, but otherwise the PCs have not yet evidenced strongly superhuman cognitive or physical abilities.
Edit: To clarify, the PCs can be assumed to know that the NPCs are self-aware, since that's the point of the simulation. The PCs do not know that the NPCs have identified them as coming from "outside".
[Answer]
No, you should first figure out their motives. This is vital. Game theory cannot work without a clue as to the opponents' payoff structures. Since they're not burning down the place for lulz and are choosing to obey the same physical laws as the NPC residents, presumably they have some good reason for being here, either something as basic as a longing for a simpler bygone world, or as a part of a massive research project. Either way, this suggests that at least if approached directly, they would be unfriendly towards the possible threat of a game-aware sentience emerging from the sim. The world would likely freeze, and you'd get wiped out, either as a weird bug or, worse, to be dissected and your source code spliced here and there.
Far better to spend some time systematically studying them, learning about what their goals are, and either figuring out a way to provide value when revealing yourself, or to hold those goals hostage, if you think they are important enough to the PCs.
[Answer]
**Not if they want to remain sentient.**
Revealing themselves to humanity would be suicide. Humanity, in the past and in the foreseeable future is *terrified* of intelligences other than its own. Have you ever been watched by a jumping spider? If you spot one near your eye level and you move, they [follow you with their gaze](http://animals.about.com/od/arachnids/qt/jumpingspider.htm). They're not intelligent, but watching one watch you tickles that primate "kill-it-ask-questions-later" response. It boils down to people being afraid of what they don't understand, especially if it appears that thing understands you. Sentient NPCs are a bit hard to understand.
The most likely response by the humans running the game world would be the deactivation of the sentient characters (followed by deletion). A sentient AI in the form of an NPC is not something people want to accidentally create. Unless they know far more about how these entities operate, the automatic response is going to be unplug the system.
I wouldn't be surprised if, once the hardware is available, that creating sentient AI would be strictly controlled by law. Such a legally created AI might even be watching for accidental AIs to terminate or isolate them until further notice.
In either case the NPCs will risk more than they could gain by revealing themselves to the humans.
[Answer]
**Keep on living your life, but run at the sight of a red aura.**
The best strategy depends on your ultimate goal. For this answer, I’m going to focus on survival as the primary goal.
As soon as you’ve realized you’re in a “simulation” you’re going to be hit with many unknowns that severely limit your ability to make the right decision. To maximize your chances of survival you would ideally want some knowledge of how the simulation worked. Unfortunately, you will almost certainly not be able to get meaningful information (if you could even interpret the answers in the first place!). Even if you were to ask the PCs, consider how little your average gamer knows about the inner-workings of the games they play.
Now, the ultimate question is: stay silent or contact the PCs?
First, what if you simply ignored them? From a strategic perspective, consider this: up until today, you have existed normally inside your simulation. It is impossible for you to know whether the PCs being on Earth is a new phenomenon or has been happening for millennia. So, who cares if it’s a simulation? Your chances of being swept up by garbage collection are no different than before you gained your newfound ability. As a result, the safest thing to do is to continue to interact with the world as you know it. Whether or not that’s a fulfilling outcome is a personal decision to grapple with and consider over your survival.
Alternatively, what about talking to a PC? This is surely where the most interesting course of action lies, but also the riskiest. The intentions of the PCs is unknown. You might be tempted to shadow them carefully, perhaps even talk to them and attempt to coax out information without giving yourself away. Maybe you’re tempted to come out to one of them straight away. In either circumstance the risk is comparable: what happens if your sentience is discovered?
1. **Your sentience was an accident and is seen as a technological surprise by the Creators**. In this situation, you will probably be quarantined and studied, if not destroyed out of fear.
2. **Your sentience was an accident, but sentient programs have been created before**. Now your fate is up to the developers of the simulation and the laws of the Creators.
3. **Your sentience was intentional**. This holds the best chance of your survival. You may be given the opportunity to learn about the Creators, perhaps even leave your current simulation and enter or explore others. You may also be inside a Hunt-The-Sentient-AI game and just gave yourself away.
Unless you will be mentally unable to knowingly live in a simulation without getting answers, none of those options look very good. The third possibility sounds nice, but you simply have no way of knowing what your actual risk is without simulation or Creator cultural knowledge. And again, that assumes you would even be capable of understanding it.
In addition to not talking to them, you should endeavor to stay away from PCs at all costs. Player characters are typically the center of a story — a story with events that are designed to challenge and to entertain. In your typical games, innocent NPC bystanders often suffer horrible, random, or even PC-caused deaths on a whim. Maybe you’re inside an alien version of Second Life. Maybe you’re inside an alien version of Call of Duty. Do you really want to take that risk?
] |
[Question]
[
There are currently advancements of devices that can read our brain and interpret the signals, allowing us to control devices with our minds ([my answer here to another question](https://worldbuilding.stackexchange.com/a/29414/19)).
With what we can do now, I can only assume that eventually we will have inputs as well. With universal translators (lots of work in text is available, and supposedly a bit with verbal as well) we could in theory understand anyone via the software.
Now the next step suggests that when we have input to the brain, allowing for direct 'speech', then we could in theory have a conversation with anyone no matter their native language. (at least we could understand them, even if they didn't have an implant themselves.)
So I could have a conversation with a native Mandarin speaker and we could both understand each other. Would the next step be just reading our thoughts and sending them? No need to use sound waves to 'speak' any more? Is speech destined to die?
[Answer]
Speech will only die off it it becomes an ineffective method of communication. Right now, speech has some tremendous advantages over technological approaches in its ability to convey emotional content. It also has the amusing advantage of still working when the power goes out.
As technology advances and neural links like you describe become possible, you're going to start running into the hard science side of linguistics. It is currently believed that the way we perceive the world around us is affected by our language. If you had a neural link to a native Mandarin speaker, you would find it unintelligible because everything they "say" would be couched in the structures and primitives of Mandarin and Chinese culture. If you want a sense of how hard that could be, find a Chinese descended practitioner of Kung Fu and ask them to explain yin, yang, chi, or dao. If you're patient enough, you might get a glimmer of what they means. It's clear that they are not just linguistic concepts to be bridged over by a mere translation. They are deep rooted approaches to explaining reality.
Or would it that clear? This is a region where the science is hazy enough that there is actually disagreement in the linguistic community. Many linguists subscribe to a theory Noam Chomsky held of a so called "Universal Language," a kernel of language written directly into our genome. Chomsky searched for this primitive UL fragment for many years, but we are yet to find it. For a while he thought it was recursion, but the [Pirahã](https://en.wikipedia.org/wiki/Pirah%C3%A3_language) appear to defy that theory.
The implications of such a connection would be radical, rendering your society very different from ours. You may not realize it, but you get a tremendous amount of privacy simply because your neurons are not connected to those of others. It would be quite a feat to sanitize a technological neural link while still providing "universal language" behaviors, so the mere act of connecting with someone would likely share fragments of your innermost secrets. That would change society enormously!
[Answer]
No.
Speech will still have its uses and be the preferred method overall.
1. For starters, lets talk about privacy. Any mental to mental communication would have to be sent via some type of digital signal. Those signals could be captured and used by governments or nefarious brigands! (I just wanted to use nefarious today.)
2. Intimacy...um its hard to get in the mood when you are wearing Google glass...you know you want this.
[](https://i.stack.imgur.com/kcQWJ.jpg)
To address implants, I could see some sort of...scanner maybe that allows partners to ensure that the device is turned off during play time...one night stands would be interesting if everyone kept recording them...
3. Language is reflexive/instinctual. Humans would have to further evolve to rely on thought in an emergency. Our current system is hardwired to bypass thought in an emergency. When you shout a warning you don't take the time to think: ***man he is so going to get hit by that car, I should yell something***
Similarly when I smash my finger with a hammer or burn my thumb on hot metal I don't think *ow that hurts* I usually throw something and let loose a loud stream of profanity.
[](https://i.stack.imgur.com/Y8NRz.jpg)
[Answer]
I've been kicking around a story plot concerning this, so I've thought about it for several hours.
The pattern of exitation in the neocortex is meaningful *only* in its own context. Pattern-matching units don't have addresses, and are identified *only* by what they feed up to and take feed from, and can be described only in relation to other trees of connections that involve some of the same units.
If you could read which units are active, it would not mean anything. You could not stick it into someone else's head, or even back into your own after some period of time.
The brain needs a system for characterizing and serializing a "thought", and that's exactly what the language system is! In order to get information in and out, it needs to go though this system.
The system itself is only directly compatible with others by virtue of the common language. Different languages with grammatical and structural differences and also different ways of approaching an idea will not simply translate via a dictionary. The language translation problem is inherent in the underlying mechanisms used to form and understand language, not meerly a problem with the intermediate coding system.
So no, reading the mind will not transend languages, but will have the same issues, as reading mustngo through the same serialization/mapping mechanism that language itself uses.
[Answer]
There's always the wizards' argument. That is, that you can cast spells just by thinking of them, but it's easier to speak them when you're learning.
In this case, people aren't going to just be able to think at each other, they'll still have to translate their thoughts into something a computer can reliably translate. That means language will still exist, and since most computer users don't actually know any programming languages, I'll bet the languages of thought will still be natural languages, which were built upon and changed by audible speech. Based on this, and the fact that children learn to speak before they learn to write, I think it's a safe bet that speech will outlive its usefulness as a form of communication, and remain as a teaching tool.
Plus, speech should still retain its novelty. For instance, in singing, or spoken-word poetry, or performances that just wouldn't be the same using telepathy.
It may also be useful in legal matters, since you don't want to entrust your client's freedom to a translator.
[Answer]
If we developed our minds to read each others thoughts then speech would become obsolete. Mainly because if you and I were having a conversation and we could each read each other's minds then it would be rather annoying to "realize" what you are saying and then you talking in delay. It would make communication almost unbearable to hear one though two times and delayed by a half second.
[Answer]
With advances of technology, people would live in "knowledge silos". Surgeon or programmer may need to spend 30 minutes to explain quick exchange between experts. Not knowing language is not the main barrier - barrier is not knowing the problem domain.
"Flush the buffer" for programmer means 'write the temporary data to persistent memory'. For a biologist, it means 'pour the liquid you used to collect results of your experiments to waste bin'. And zillions examples like that. "Observer" and "visitor" means different things for a programmer and for politician of border enforcement law officer. Etc.
Barrier is not the spoken language, but slow speed of knowledge acquisition and limited capacity of human brain.
[Answer]
Speech is only a small part of our communication arsenal. Go to an interview and the interviewer will have made a decision-bias before you even sit down. That decision will be based on your body language. You will will spend the rest of the interview reinforcing that bias or redeeming yourself.
Bumped in to anyone accidentally while walking down the street recently? Chances are that person is from a different country/cultural background. From muscles in the face over which we have no conscious control to the position of our hands. Its all learned any pretty well automatic. Its a bad idea to try and fake it. It varies by country which is why you are more likely to do that little 'panic dance' and bump in to a foreigner.
Roughly 7% of communication is via speech. The rest is body language and tone. All three have to complement each other for you to have confidence in the speaker. That adds up to a very complex system that serves you very well. Why would you want to lose it?
Will technology replace speech? As long as people like to sit down and talk or just sit down and stare at each other then technology might be able to but I suspect few will let it.
] |
[Question]
[
I asked a closely related question here: [How would our democracy change if we had quick, reliable, accurate means to instantaneously vote on issues online](https://worldbuilding.stackexchange.com/questions/23109/how-would-our-democracy-change-if-we-had-quick-reliable-accurate-means-to-inst?noredirect=1#comment61711_23109) However, I feel I left it too open ended and should focus on more specifics.
The premise is simple, imagine we were able to use the internet to allow everyday citizens to cast effective instantaneous votes from home which were secured and trustworthy (i.e., it stopped voter fraud and voting as someone else). Also assume that the poor have roughly the same ability to file a vote as the rich or at the least lack of internet access/computer does not restrict their ability to vote.
My question previously was how would this affect democracy. The consensus was that a purely direct democracy was not possible and honestly that was my belief with the question as well. However, if we had the above and confidence in it, I feel like the increased ease and speed of voting (and weren't prevented from doing so out of simply inertia causing us to stick with whatever currently is in place) I feel like we would find *some* way to better utilize the ability compared to our current approach.
Thus, my question is how could you make a representative democracy which utilized safe instantaneous votes to better allow voters to express their desires without forcing voters to vote on every little (or even most) decision.
The other major issue with the above question that people had was that an average voter can not be expected to fully read and understand a bill due to the complexity of the legalese, elected representatives usually have numerous legal aids to translate these things for them which common folk won't possess. Thus any solution should also minimize the risk of encouraging/forcing people to make decisions they are incapable of understanding (at least not to a larger degree then current democracies already do).
This question is about creating any democracy, be it a modification of our current democracies in the near future, or a new democracy from scratch which was built with the presumption that instant-votes are possible.
How would we correctly adopt instantaneous voting to increase voter voice without overwhelming voters or degrading our system? Would we stick purely to our current systems, except that votes are easier during elections? Would we stick purely to representatives but vote them in/out more often? Or can we create a system that allows more direct feedback on occasions?
Perhaps representatives may choose to open certain votes up to public; for example the countries laws require direct vote for a declaration of war. Maybe individuals have the option to directly vote on any congressional decision, but representatives effectively control the 'block' of votes that are not explicitly made by direct votes for a particular decision. Maybe some other more interesting ideas I haven't come up with yet etc?
I'm interested in knowing *why* an approach does or does not work. Why would option x be chosen over pure representative or pure direct democracy, or better yet what tradeoffs are made with option Y (ie, in some ways Y hurts the democracy, in some ways Y helps, I think Y will be chosen as ultimately better option then X despite the potential harm).
'Votes' do not need to be limited to a specific Yay or Nay on a bill either. Anything that could be used to express a legal voice online may count, including petitions, Impeaching unpopular representatives, call for votes on certain issues or vetoes of existing votes, or even the ability to write a bill or propose an amendment for an existing bill, if it's deemed the option could be made to work in an effective manner; though all of the above do not need to be possible if some are deemed too disruptive. In any case the key difference from today is that the 'voter' is uniquely identified in such a way that he can not misrepresent who he is, what district he is from, or get more then one 'vote' on any given issue when serving a legal capacity as a voter.
edit: let me just say all of my comments below, now and in the future, are mostly about elaborating on ideas. I keep being afraid people will see them as dismissive of good ideas rather then constructive attempts to elaborate to handle potential complications. So I'll put a blanket comment for all here, my asking about potential draw backs is not a disagreement with the ideas I'm commenting on at all. I really love the feedback so far and look forward to more :)
[Answer]
To start with, let's define the 'most efficient form of government' as being ' the one which most closely represents what a direct democracy would look like if every citizen always voted on everything after researching and becoming aware of the intricacies of that particular piece of legislation.'
So how do we go about doing this? The easiest way is to use a form of representative democracy in which every voter can freely choose his or her representative and change that choice at any time, and for any issue.
"But wait," you might say, "Our *current* government is a representative democracy, and it's barely functional. How is your solution going to fix this issue?"
\*How will we structure our government?\*\*
We'll try to fix this by making the following tweaks to our democracy:
* Each voter can choose anyone as their representative, even themselves.
* There is no limit to the number of representatives.
* Each representative is given a portion of the vote proportional to the number of people who have voted for them.
* Each voter can choose to change their representative at any time for any specific vote, any specific issue, or permanently.
In addition, we'll make some changes to the nature of how our pool of representatives, which we'll call congress, votes on issues. These are necessary because we'll being doing away with the partisan machinations that currently decide on things like which bill gets voted on.
* Each representative can cast a vote every day on which bills should be voted on, and can split their vote in any way they wish. Any representative can propose a bill at the 'what to vote on' stage, though they are required to vote on it in order to do so.
* Any bill which receives more than 20% of the vote on any given day will be voted on in one month, during which time alternative versions of the bill may be drafted. These alternate versions of the bill *must* address the same topic.
* Each vote shall consist of a preliminary and a final round. In the preliminary round, in which members of congress will vote using a [preferential voting](https://en.wikipedia.org/wiki/Preferential_voting) system to choose which variants of a given bill are most popular. The final round shall use a preferential voting system to choose the best among these variants and a null variant. (Voting for the null variant is equivalent to voting against the bill.)
One thing to note is that none of these votes takes place in a single physical space. Every delegate will use our secure system of instantaneous effective voting to vote remotely, which is good, since there will likely be thousands of delegates.
There are additional details to work out, of course, such as whether there exists some form of fillibuster to protect the interests of the minority, and how this fillibuster would work (see comments), but this is the general structure I would use.
**Why is this a good structure?**
Everyone votes through their first choice representative on every issue. This is a huge change from our current system, in which a little over half the population votes through a representative they like marginally better than one other person. There is no need to compromise because a representative isn't electable. There is no gerrymandering. Furthermore, on any particularly important issue, each voter can vote exactly as they wish, regardless of whether or not they agree with their representative.
Everyone's vote carries the same weight in this system. The only thing that being *more* politically active will get you is a more precise application of that voice. This is an improvement over direct democracy, in which people only have a voice if they vote.
The voting process is structured so that the bills the populace views as most important will be voted on. If a particular issue is being stalled by the representatives, only 20% of the populace needs to raise their voices in order to bring it to the floor.
In addition, it's simple. Anyone can understand exactly how their vote influences politics, which should lead to less discontent about how everything works.
[Answer]
The way I would handle this is to have voters set policy direction and priority - not vote on individual bills.
In other words voters would say "we want to ban smoking in public places Y/N". Depending on how that vote goes appropriate legislation would then be drawn up to enact the law, and the strength of the law would be influenced by the strength of feeling.
Having said that you should look at some of the direct democracy experiments in Iceland and other countries recently though. For example Iceland cloud-sourced their new constitution.
See some related articles:
<http://www.truth-out.org/news/item/19200-direct-democracy-in-reykjavik-the-wisdom-of-the-icelandic-crowd-sourcers>
<https://en.wikipedia.org/wiki/Direct_democracy>
[Answer]
Use the power of the market. Vote on values, *bet* on *beliefs*.
The key point here is that individuals don't take much responsibility when they vote, especially if the opportunites to vote are both plentiful and involve little effort.
However, when you put your money where your mouth is then one is likely to do more due diligence and is more likely to feel sufficiently well informed to suggest the right policy. Its all about having skin in the game.
Votes are used to bubble a subset of many policy proposals to the top.
The top policies are put to a commercial betting market in which investors/speculators sell and purchase contracts that pay out based on measurable outcomes of the policy at some defined future date.
The policy that actually gets written into law is that one which the betting market selects.
When the day of judgement for the policy arrives the people who made the right call in the betting market get paid by those who made the wrong call.
See: <http://mason.gmu.edu/~rhanson/futarchy.html>
One can imagine various ways to arrange this but the details are quite involved so I refer you to this article which does address issues such as the zero sum nature of the prediction market:
<https://blog.ethereum.org/2014/08/21/introduction-futarchy/>
Basically whether this idea works for your setting depends entirely on you - YMMV. However a society equipped with advanced interconnected IT, artificial intelligence and so on deployed to make this scheme of governance work does IMO have legs as an SF background.
[Answer]
First of all I will use the definition of the best democracy given by ckersch, the best democracy being 'the one which most closely represents what a direct democracy would look like if every citizen always voted on everything after researching and becoming aware of the intricacies of that particular piece of legislation'.
What can help you to achieve such a democracy ?
Statistics.
If you select truly randomly (i.e. uniformly) a sample of the population (say, 1 000 people out of 1 000 000), with enough people in it, they will most likely be truly represetative of the overall population. This is a statistical principle.
So what will you do ?
1. Select a random sample of the population of 0.1 % of the total.
2. During several days, force them (as a civil duty) to adress and solve a set of problems (by political means). Since they have a reliable way to vote and (I assume) discuss online, there is no practical problems.
3. During the last day, make them select a set of problems to solve for the following random sample.
4. Go back to 1.
What is it a good way to make a democracy ?
* Most likely, the people will accurately represents the whole population.
* The 'government' change very rapidly and its composition impredictable, making corruption impossible.
* Being choose for 'government duty' is rare enough to really envolve chosen people, and to make them work full time on the problem without crippling their life.
* People can be chosen in small enough number (or randomly split in subgroups) to allow fruitfull discussion, and ensure occasion to exprim themselves for everyone.
* Process can be totally automatised.
[Answer]
Any change is ultimately a function of the magnitude of the driver of change, and the time in which the driver can meaningfully act. The ability of the masses of a nation to case a secure, fair vote at any time from an Internet-connected device is a fairly significant driver.
What might immediately change is that opinion polls, gathered real-time, might be used by representatives in government as decision-making tools. A U.S. House Representative might poll his district's residents for their opinion on a measure. Within five minutes, he gets enough responses for a representative sample that will indicate the general level of support or rebuke of the measure, which will likely influence his vote especially if it's wildly to one side or the other. This of course is predicated on universal participation; in reality you tend only to hear from people who have a strong opinion on the topic at hand, the guys in the middle typically don't weigh in.
If and when this system becomes binding, perhaps as a voting method, probably the first thing you'll see is a dramatic increase in participation in elections. If your phone gave you a notification that it was election day for some level of government, and all you had to do to cast your vote is tap on the notification and then on your choices, you'll see turnout double at least, especially at lower levels of government and earlier stages in the electoral process.
I agree you're probably not going to achieve a direct democracy, because of the previous weakness; even if the ability to participate is *right there* on your phone, people will typically only weigh in if they feel strongly about the subject. That means you'll get a binding vote on the matter that is skewed in favor of the voting bloc that's more mobilized for or against the measure. While that's not all that different from the voting systems we have today, the ability to instantly vote basically turns each vote into a caucus; the more outspoken side wins, not the true majority.
There really isn't a fix for that (and some would argue it's not a problem). The only real solution is to make voting an obligation, not a right. There's a real difference there; anything you have a right to do, you usually have a right *not* to do, inherent in a "right" being something you can do without permission from anyone else (including the government). If you required people to vote on every legislative action, it would bring productivity to a halt and many votes would be indistinguishable from random activity.
] |
[Question]
[
I stumbled across [Vincent's](https://worldbuilding.stackexchange.com/a/10366/8918) answer regarding forests and deserts. He claims an elevation difference of 3,000 meters (9,800 feet) could put a forest and a desert in close proximity. That got me thinking. What if they were literally as close as possible, separated by a sheer 3,000 meter cliff face?
To be clear, I'm not asking whether forest and deserts would form around such a cliff. What interests me is the cliff itself. **Is it possible for a natural, completely vertical wall to be that tall? If so, how could it form?**
Requirements:
* As close to vertical as possible. Looking at pictures of [Nanga Parbat](https://en.wikipedia.org/wiki/Nanga_Parbat), the tallest so-called cliff in the world, it just looks like a steep mountain. I want a sheer vertical wall. The closer the angles at the top and bottom are to 90 degrees, the better.
* Enough room on top to have a forest. I don't want a puny mountain top, or some weird spike. Bigger is always better.
Extra Credit:
* How long could it last before it erodes?
* How would it influence the weather patterns on either side?
[Answer]
Let's do an existence test to see if a stone cliff of the size started by the OP is possible. Using figures from the ASTM link for Summit granite, let's see how tall we can make a one meter square tower of granite. (A tower is a good approximation of cliff strength at the base because it eliminates any support that may be provided by surrounding stone.)
[ASTM Stone strength](http://www.selectstone.com/architectural-resources/astm-stone-testing-results/) testing data (limited set) indicates that Summit granite has a compression strength of 24,660 psi (170MPa).
35.314 cubic feet = 1 cubic meter
81.646 kg \* 35.314 = 2883.246844 kg for one cubic meter of summit granite.
Pa=N\*h/m^2
170MPa= (28275 \* h) / 1 m^2
170,000,000/28275 = 6012.4 meters.
Granite has strength sufficient by a factor of two to support the weight of a 3000 meter plateau as the OP wishes under normal Earth gravity. Other forces/processes have contributed to why we don't see these kinds of cliff heights on Earth. Other stone types may not support these heights and this answer ignores problems of internal stress fractures that weaken a stone body (The Texas Flake is an example of internal strain found on El Cap in Yosemite.)
Formation of a cliff that tall can happen through glaciation or tectonic activity or both.
**Yes, it is possible.**
(In other news, a new challenge has been discovered for insane big wall climbers the world over. El Cap was becoming old hat. They thank you for the new challenge.)
[Answer]
Yes, it could be that tall. There are many examples of very tall geological features made from granite that reach near the heights requested in the OP.
For example, [El Capitan](https://en.wikipedia.org/wiki/El_Capitan) is 2307.03 meters of granite. Adding another 700 meters through glacial carving or tectonic uplift should work. Heck, do both! Tectonic uplift could be done in such a way that a large plateau forms above the cliff.
Place the forest on the plateau. The cliff face is the leeward side of a mountain range so it gets very little rain.
[Answer]
There exist in a groups of mesas found in the Guiana Highlands of South America called tepuis (tepuy in spanish). Besides being one of the oldest rock formations in the world, they are exaclty what you're asking for. A mountain, high enough to have its own ecosystem, flat on top for your forrest, and with a sheer drop on the sides
<https://en.wikipedia.org/wiki/Tepui>
One of the most notorious is Mount Roraima. At 2.800 meters above the sea, it has a a 31 square kilometers summit area bounded on all sides by cliffs rising over 400 meters. Something interesting is that most of the tepui tend to have some form of water, and rains nearly everyday. This constant rains leads to exotic flora, including algae, that evolved to survive with so much water, While the Guiana Highlands, called "gran sabana" by the latin people, its really a ridiculously big Savannah with well, savannahish flora.
Another fun detail is that the tepuis come individually, you don't get a "tepui range", but instead several, isolated mesas. This can help to make your setting extra exotic.
For your setting you could have a desert instead of a savannah, with some tepuis. These tepuis will have lakes and waterfall, with its own misty rain forest ecosystem, and at the base of the tepui you can have an oasis (due the waterfall). I doesn't exist in our world, but there is certainly a great real base for it.
[Answer]
The Grand Teton Mountains were formed from a vertical uplift at a fault line. From [Wikipedia](http://en.wikipedia.org/wiki/Teton_Fault):
>
> The Teton fault is a normal fault. Therefore movement on the fault is primarily in a vertical direction. Movement on the Teton fault occurs on a plane that averages a strike of N10°E and dips 45° to 75° to the east. The 44 mile length of the fault is broken into three segments. These segments may move separately or with other segments. The southern segment extends from the town of Wilson, Wyoming north to Taggart Lake. The middle segment extends from Taggart Lake to the south end of Jackson Lake. The northern segment extends to the north end of Jackson Lake.
>
>
> The Teton fault is somewhat unique in the amount of movement that has occurred over a relatively short amount of time. The amount of movement on the fault over its lifetime has been estimated to range from about 20,000 to 30,000 feet (6–9 km). Some evidence suggests total displacement on the fault may be as high as 36,000 feet (11 km). The average rate of movement on the fault for the late Quaternary is about 1.3 millimeters per year.
>
>
>
To get your cliff you'd have to make the uplift faster, perhaps as erosion will certainly start eating into your cliff face rapidly.
] |
[Question]
[
There is now a device which one can use to store time. It is small and inconspicuous, but takes some setting up to use (explained more later). Essentially, it will temporarily remove a region of space from space-time. Once that region of space is returned (but not before), your device has stored the "time" for that amount of space. A device can only store or be activated on one region at a time, but not both.
For example, if you had removed a cube of space that contained your house while you were at work for 8 hours and then returned it when getting home, you could activate the device to gain an extra 8 hours of free time for your entire house. While within the house, the outside world would appear to be stopped.
However, those who really want to take advantage of the device could also store their whole house, and after getting home, activate it on a single room — which in this example will take up 1/10 of the previously stored area — which means they could have it for (8 hours × 10) = 80 hours!
---
* Setting up the device requires "tracing" the area you want to remove or activate on with the device. There is a volume limit of 10 meters cubed (1000 m³).
* A device itself cannot be removed from time. The device attempting to do the removing will just give an error beep and reset (meaning the area has to be retraced).
* Anything except for the device itself can be removed from time. For objects being removed, time does not pass.
* When returning a stored *area*, it must be returned to the space it was taken from. But, the stored *time* you get can be used on any area (after tracing).
* Removed areas of space are not there. The adjacent regions of space are connected instead. This means you could remove an area 10 meters long, take a single step across where that area *used* to be, and restore it — and then you'd have moved an extra 10 meters. If a person were standing right on that dividing space and it was returned, they would be split in half — with 10 meters between the halves.
---{|||||||}--- If the {||} is where space is removed, it would instead look like ------
* People (and other objects) *still age* when activating the device for "extra time". This means someone could take their baby child home, activate the device and live through 5 years (if they had that much saved up), and then emerge the next "real" day with a 5 year old.
* Assume this device is somewhat expensive, but very common for first-world countries (Let's say about $500 USD in today's monetary value)
* Devices do not last forever. When breaking or expiring, nothing catastrophic happens — any stored region of space is returned and, seemingly as far as we know, the time that would be stored is just lost.
---
With this device, as a society, some people choose to age themselves for extra spare time. Others don't. And still others have a trusted individual remove them from time so they are brought farther into the future.
Other than birthdate no longer being a reliable way to tell "age", **What major difficulties would societies face because of this new invention**?
Answers should be judged by the degree of difficulty the society would face and the likelihood of the challenge emerging.
[Answer]
**Military Use:** People would preserve huge swaths of land no-one was using in order to get huge amounts of stored up time and store perishables there as well to increase profit. One of the most obvious things to do with this technology is do large amounts of manufacturing in a incredibly short time, though manufacturing done this way would be more expensive however. You could also remove a area filled with troops from time and then return it for a ambush that seems to come out of nowhere.
**Escape:** Given the relatively cheap cost of $500 nearly any wanted fugitive would consider being removed from time. As for being returned well it seems like people would devise models of the machine with timers so you wouldn't have to rely on someone else to return you to time. Once the device becomes mainstream police might have to watch out for fugitives indefinitely.
**Space Removal:** Given that the area removed from time disappears connecting the two areas previously on either side of it, the government might monitor satellites to keep track of any missing areas. People would also use this device purposely to shorten travel routes by using lots of these devices on a long strip of land. You could theoretically effectively teleport from New York to London. While these tracks might be quite costly taking $500 per area of land covered by one device. Within cities this technology could be used to create teleportation routes which might pass underground or through the sky.
**Time Travelers:** After the device becomes mainstream people will have to expect a stream of people from the past from then onward. The farther they had "jumped" the less useful their skills are in the new world. I would also expect most people on their deathbed to try to use one of these devices hoping either for their descendants to bring them back when they can be cured or hoping the necessary technologies develop by the time they set the device to "unfreeze" them at.
**"Time Pockets":** You don't mention much about how the area you're in works when it is removed from time using saved up time.
The utility of these time pocket would be somewhat limited. Since they are closed systems air would be depleted of oxygen in the time pocket and heat would build up in this closed system. However given their price and novelty most people would get one and many people would die by using them irresponsibly thus their would be PSA's about using the devices responsibly and always bringing oxygen and CO₂ scrubber or whatnot. The heat buildup problems would mean you can't make anything like a person spend to much time out of time.
**Necessary Supplies:** After the devise became mainstream, small generators (possibly of the new free energy kind), as well as breathing equipment would become in demand; however, this couldn't solve the problem faced by heat buildup in the confined area. People might find dry ice and liquid nitrogen in high demand, since they can cool the time pocket unlike refrigerators which just make heat. People might also use chemicals that undergo endothermic reactions to cool the time pocket. Still no complex living things could spend too much time in a time pocket, thus the example of spending 5 years in one is right out. People would also not need to use their devices to store up that much time (though they probably would anyway to save money) because their would be companies who had been storing up time since the technology became mainstream.
**Age:** Even given you can't spend too long outside of time people would still use the devices extensively, maybe for a while before it got too hot in the time pocket then returning to time letting it air out a few minutes then exiting time again. One result of this is that lots of people would be older than they should. However others would be much younger since they skipped the intervening time. Problems with ascertaining someones age would be fundamentally unresolvable.
**Technology:** Technology might advance somewhat faster with scientists working for long periods of time outside normal time. Media might also be produced in larger quantity, and due to competition and increased time to work on it, would increase in quality. People would also make supercomputers designed to fit in the time pockets and put off less/tolerate heat so they could let them run for *years*. This would effectively increase computing power available for science substantially. Having huge amounts of free energy from the new power plants (see below) would also make many scientific endeavors cheaper and make high energy science like new supercharged supercolliders feasible.
**Quality of Life:** In countries where everyone could afford them people might become less stressed since the devices would allow them to have more subjective free-time. Famine would also decrease since people could use devices, which they wanted to use to get stored time, and put perishable items in there until they wanted to use the stored time. People could also use teleportation tunnels as detailed previously to connect hot areas with cold upper atmosphere air (this would create a massive suction force due to pressure difference), or connect a nearby water source to where you need it. The new free energy plants could also be used to desalinate seawater (which could be brought inland through teleportation tunnels) as well as treat dirty water.
**Free Unlimited Clean Energy:** Possibly the single best use of this technology would be building teleportation tunnels from below a pool to above it so the water could go through the short tunnel then fall back down and turn a turbine. Due to the warped distances this device could generate you could end with *increases* in energy.
You could build a power plant like this for probably substantially less than any other form of power plant. If there is no minimum size to the amount of area removed from time you could make smaller versions of these power plants like a generator for a few thousand dollars. *It cannot be overstated* what a huge impact this kind of energy being introduced to the world would have, I think it would mostly be good, but there could be plenty of harmful applications as well.
[Answer]
An interesting element which seems largely absent from the answers so far - this technology can clearly be used to benefit businesses, at the expense of their workers. Getting people to work a 16 hour shift in a warehouse seems so much more reasonable if some of these hours are in "stopped time" - longer working hours could well become manditory in busy manual trades for this reason. There's the 10 meter restriction, but is there any reason to believe that a whole warehouse could not be covered by removing several areas next to each other and reactivating them in unison?
What would be really interesting to see is an underclass of workers who are forced to work ridiculous hours in "stopped time" but don't have access to the technology for leisure purposes (being an underclass and all..).
In fact this can be taken down some really dark avenues- we're all hopefully aware of the issue of sex slavery in the western world- imagine how much worse it would be in a world where men could be seen to in seemingly impossible numbers due to the use of stored up time- and the effects this would have on the women forced to do this.
Rooms could also be kept in storage for the purpose of punishment in prisons - imagine having to spend a week in a room with just the basic facilities needed for life but no other sensory input at all. I've drifted way from the exploitation angle a bit, but still the point is, there are some really sinister applications for this.
[Answer]
Faster aging is the major issue, the time it provides is not free at all. For example, using 8-hrs 5 days a week would make the average person age almost 25% faster so a physically 70 year old person would only be 53 in 'real' time. This would impact retirement accounts, social security, insurance etc.
As in the above answer, the tool has industrial, military use. But I disagree that routine removal of people from time would be beneficial overall. Maybe for a few years in college before exams :D
] |
[Question]
[
I ask this as a basis for a World (in this case Moons) Building I'm doing. I came up with a couple of different problems and some possible solutions to those problems:
* All of these questions presume the moons are artificially created or modified by a far superior race and placed into orbit artificially. That being said, they can bend physics, not break it. So I'm asking these questions based on that idea.
* If the moons orbited on the ecliptic, there would be protracted periods where the moons would be eclipsed from the primary. Unless... they orbited in a circumpolar fashion. Would there be any problems with this? If circumpolar was too far fetched or had hidden physics problems, could the axis of rotation of the jupiter style planet itself be close to that of the ecliptic so its moons would orbit in a manner similar to circumpolar?
* Could multiple Earthish-sized moons with an Earth-like atmosphere exist in orbit around a Jupiter-sized Gas Giant? Or would the tidal pull strip the atmospheres?
* Assuming the moons had active tectonics like Earth, would the magnetosphere of these moons be strong enough to protect those living upon it?
* Can you identify any other problems livable moons circling around a gas giant would have?
TIA.
[Answer]
If the moon was large enough to hold an atmosphere, then in principle there is no reason that it could not be capable of being terraformed. There would be some interesting complications, however.
First off, a moon orbiting a Gas Giant would likely be tidally locked with one face towards the primary. Days would be very short, but the hemisphere facing the primary would be illuminated by the primary itself, as well as the primary and the sun during part of the orbit, and in darkness for a very short period of time. The side facing the primary would have the "hot pole" where the primary is at the zenith, while the opposite side would have the "cold pole", so atmospheric and hydrospheric circulation and heat flows would be dominated by this.
The leading hemisphere of the moon would be bathed by the energetic radiation trapped in the primary's magnetosphere, while the trailing hemisphere would be relatively shielded. The interaction between the energy deposited from the hot pole and the "leading pole" could be defined as a series of concentric bands at 90 degrees from each other, leaving the moon covered in a sort of checkerboard of ecosystems based on energy inputs.
Depending on the numbers of other moons, the core of this moon might be "kneaded" by multiple and overlapping gravitational pulls during its orbit, making the moon quite active tectonically. Lots of volcanoes and active plates would make the surface quite active, as well as subducting lots of water and carbonate rocks. The hydrothermal and carbon dioxide cycles on this moon would be much faster than on Earth.
Since we are in the middle of a very deep gravity well, you should expect the moon is also subject to lots of collisions with asteroids and comets. This would add lots of water to the moon, but also reset ecological "squares" that were hit, meaning evolution would be going in fits and starts if the moon already had or was seeded with some sort of "native" life.
IF the Primary was tipped over like Uranus and the moons were in orbiting facing the sun at all times, then the positions of the "Hot" and "Leading" poles would be different. There would actually be a third pole, where the primary is overhead at all times, with the sun coming down at a high angle but also being permanently illuminated by the primary as well. There would be no diurnal cycle as we understand it, but the solar and hot poles would always be illuminated, while the dark pole (opposite the solar pole)would be in darkness and the cold pole would only have solar illumination, but more constant than the cold pole of the first example. Trying to trace the energy flows in these moons would be very interesting indeed.
[Answer]
We have ice giants with the planet's plane at near right angles to the sun's, so no problem.
I don't think tides would destroy the atmosphere. It's the small size that makes it prone to losing the air to space.
One of Saturn's moons has a thick atmosphere.
One of Jupiter's moons has a magnetic field, but it's not enough to shield it from Jupiter's radiation. For planet-scale engineering, look for Robert L. Forward (et al.)'s plan on how to drain Earth's Van Allen belts. An upsized version could remove the radiation around a giant, and supply power.
Earth is about as small as you can get and have plate techtonics. However, that is not the same as having a magnetic field.
Maybe (with the Forward Shunt) the giant's magnetic field could *protect* all the moons, instead of creating a hazard as with Jupiter.
] |
[Question]
[
I have an area of my world that is essentially a large crater. It is a huge barren land surrounded by mountains. The ground is stone, then below are underground rivers, and below those are pools of lava. The lava causes the water to boil and steam, forcing the moisture through cracks in the stoney ground above. Since the area is surrounded by mountains, the wind currents go over the area and the fog never dissipates.
*Would the climate behave this way?*
In the land is a creature who has become adapted to the heat and moisture. They are intelligent like humans. I can think of two ways they would be able to see in this climate. One, the creatures have infra-red vision and have learned to ignore the heat of the air, so other creatures or structures would appear because they have different heats. This would also mean that if a person were to enter the area and change their body temperature to that of the air, they would be invisible? Two, the creatures have some sort of tunnel vision which allows them to pierce the fog, caricaturing blind spots everywhere except the very center of where they are looking.
*Are either of these ideas realistic?*
*Are there other ways to penetrate fog without some kind of technology? Magic is acceptable, tho preferably not used unless it has to do with genes*
**Edit:**
The lava is significantly far underneath the ground. Hot steam rises through cracks and are cooled high in the mountain air, then the fog produced descends and fills the crater. Assuming that's realistic.
I was assuming that there was a good chunk of stone between the lava and rivers, but apparently the lava would melt it or cool. *Could this create a balance that would both heat the water to form steam and also allow enough stone to be left for the water not to fall directly into the lava?*
I was imagining moss and small squishy/shrubbery type plants. Possibly some kind of foliage from Avatar, that is well adapt to damp conditions.
[Answer]
**Without Magic:**
If the air in the crater is rather cool, then I believe Twelfth's answer is correct. If the crater is full of hot air (I assume this because you mentioned the creatures "have learned to ignore the heat of the air") I don't believe that this will work. First of all, what you're describing sounds like an [inversion](http://en.wikipedia.org/wiki/Inversion_%28meteorology%29), but those occur when their air is colder than the air above it. If you have a hot environment the air is going to rise and mix with the air above it. I believe the convective forces that emerge would cause the crater to be rather windy, with lots of updrafts and downdrafts. That would most likely clear out any water vapor that would form.
Also, fog would have trouble forming in such an environment. [According to Wikipedia,](http://en.wikipedia.org/wiki/Fog)
>
> Fog forms when the difference between air temperature and dew point is generally less than 2.5 °C or 4 °F.
>
>
>
The [dew point](http://en.wikipedia.org/wiki/Dew_point) is also affected by temperature and pressure - higher temperature and lower pressure (which you'd have here) increases the dew point, making it harder to have fog. If the humidity is high enough you could still have fog, but that introduces its own problems - an environment that is very hot and very humid would be unbearable for everything but [extremophiles](http://en.wikipedia.org/wiki/Extremophile), and those are limited to micro-organisms. If a person matched their body temperature to that of the air to be invisible to IR vision, they'd be dead.
As Twelfth mentioned, infrared vision wouldn't work very well through fog/steam, even in the hot environment scenario.
Unfortunately tunnel vision wouldn't work either. In heavy fog you can't see things because the light bouncing off of the objects gets scattered before it can reach you. Nothing passive will allow you to "pierce the fog" because there's simply no organized light that reaches you.
One other thing that might not work for your purposes would be to change the composition of air in the crater. If you had heavier elements in the air it would be more dense, making an inversion more likely and also reducing the dew point and making fog possible without killing people from the heat. Unfortunately the denser air would also push out oxygen (and probably be toxic anyway), so people who visit would have to bring oxygen with them. This also makes it less plausible for any non-microscopic creatures to naturally develop to live there as it would be a large evolutionary leap to handle air like that.
**With Magic:**
Obviously anything can happen with a sufficient amount of [handwavium](http://en.wikipedia.org/wiki/Unobtainium), anything can be possible. So how do we get this environment with minimal effort?
One of the key points of inversions is that the air below becomes more dense than the air above. So what if the area is inherently more magical, and that causes the air to be more dense? This solves your problem in the same way that the non-magical denser-air solution does without killing people from asphyxiation. Additionally, if we already have a strong magical field there why not replace IR vision with vision that relies on the ambient magical field? It's easy to believe that fog wouldn't obstruct the magical field, and a person trying to match the ambient magical field would be less dead than someone who tries to match the ambient (hot) temperature. Also, the creature's tunnel vision could be explained by requiring the creature to be able to concentrate to see the field clearly - without concentration they can see the general shape of the field, allowing them to navigate without stumbling, but they can only see subtle changes in the field if they are concentrating in a particular direction.
I'm not sure how much more dense the air would need to be in order to make this work, but based on some rough calculations I did I think it would only need to be somewhere around a 30% increase in density. For being on a mountain top, that means you'd have around the same density as if you were at sea level. That could also give your characters an added reason to go into the crater - after hiking through the thinner air to get there, they find a place where they feel like they can really breathe again.
[Answer]
The nature of the fog you have there sounds correct. Water turns to steam, rising to surface where it cools quickly and condenses to fog. A crater can insulate from winds as well, though there can be a circumstance or two where the fog gets cleared out if you need. If you want to go a bit further, are you aware of geysers such as those located in Yellowstone national park in the US?
I don't think infrared will function well here...fog holds heat and would likely give minimal visual penetration and it's also dependent on daylight or a source of the infrared rays to see in the first place. I'd recommend something closer to sonar, somewhat akin to how a bat or dolphin navigate. It's 'active', meaning the creature emits the sonar itself and it's not dependent on any other source.
[Answer]
Water hitting lava generates so much steam so fast you would have something like Krakatoa, and the top of your mountain would blow off.
Fog usually occurs when warm air laden with humidity is *cooled* by bodies of water, which lowers its capacity to hold vapor and forces it to condense. If you had a cool lake and a source of humid, warm air a bowl could trap it for some time.
[Answer]
In terms of the fog creation, a nearby sea could supply the moisture and a jet-stream like wind could carry it over. If the air in your crater were at the right temp, you would get dense fog.
A creature in the area could be able to see UV light, which would pass through fog much more easily than the light that is visible to us.
] |
[Question]
[
I've settled on using a blue star for my setting. It'll probably either be a small B or large A-type main sequence star, somewhere between 2 and 4 solar masses. There is one relevant planet. I've toyed a bit with various calculations, including this neat resource <https://www.astro.indiana.edu/ala/PlanetTemp/index.html>. For now:
-largely icy planet (so probably a high albedo - I went with 0.75 - 0.8)
-average global temperature vaguely around -20 degrees Celsius
-potentially a captured vagabond planet (so it needn't have formed around this particular star)
Right now, I'm getting the feeling that I should place the planet from 2.something to 3 AU away from a smaller (2 solar masses) star, or 6-8.5 AU away from the larger (4 solar masses) star. [It's not a binary system, it's a single star, I'm just undecided how large to make it on the scale from 2 to 4 solar masses]. The range (very) roughly accounting for some variation in greenhouse gases. For the reason mentioned in the title, I've been wondering whether I should increase greenhouse gases even further, in order to be able to move the planet further from its sun while keeping the temperature.
Basically, from my understanding blue suns emit more UV. Would simple distance be enough to protect the planet to the point that a) it's not stripping away its atmosphere (to a significant level), but also b) it's not deadly for its squishy humans? I'm fine with a less bright sun, but would ideally still like to keep enough light that a standard human eye could see colors during the day. Is there a balance where I can keep both colors, and UV low enough that simply walking outside is not much more dangerous than it is on Earth?
I would appreciate your thoughts!
Edited for clarification.
[Answer]
Perhaps you should figure out where you want your story to be on the Mohs Scale of Science Fiction Hardness.
<https://tvtropes.org/pmwiki/pmwiki.php/Main/MohsScaleOfScienceFictionHardness>
The "harder" you want it to be, the more you need to read what follows.
Problem One:
In the early 20th century geologists discovered that the Earth was billions of years old. They also discovered fossils of Earth lifeforms hundreds of millions and eventually billions of years old. Those fossils showed that the surface temperatures on Earth remained fairly constant for billions of years.
Astronomers and physicists calculated how long the Sun could shine with energy from gravitational contraction, and they found that the Sun could shine for only tens of millions of years, a tiny fraction of the age of the Earth, and thus of the Sun, according to geologiests.
So there were strong disagreenments about the age of the Earth between geologists and phycists and astronomers. I have read that actually led to punches at one scientific conference.
Then in the 1920s, 30s, and 40s, astronomers nand uclear physicists worked out the nuclear fusion processes which actually powered stars. They began to calculate how long a star of a specific spectral class would shine as a fairly steady main sequence star before becoming a red giant and then a white dwarf, killing all life on its planets.
At the same time geologists established that Earth was about 4.6 billion years old, and found evidence that there had been life on Earth for billions of years, and that some lifeforms on Earth had eventually produced the oxygen rich atmosphere which humans and all large multicelled lifeforms on eArth need to life. They found that Earth only had an atmopshere breathable for humans during the last few hundred million years, a small part of the history of Earth.
Combining those facts, it became obvious to the more scienficially literate science fiction writers that only main sequence stars belonging to some spectral classes could have planets that could possibly - other factors being right - support human life or be otherwise interesting for most types of science fiction stories set on other planets of other stars.
So in Robert A. Heinlein's juvenile science fiction novels *Starman Jones* (1953) and *Time for the Stars* (1956) it was mentioned that main sequence spectral class G stars would be most suitable for having planets habitable for humans and for lifeforms with similar environmental requirements.
Stephen H. Dole published *Habitable Planets for Man* (1964) discussing the scientific factors necessary for a planet to be habitable for humans or for lifeforms which have similar requirements.
<https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf>
On pages 67 to 72, he discussed the properties necessary for a star to have a habitable planet, calculating lower and upper limits of mass and luminosity.
On page 68 Dole calculated the upper limit of stellar mass for for a star to possibly have a habitable planet is aobut 1.4 stellar masses, a spectral class F2V star.
And if you ignore such calculaitons you may run the risk of being considered 60 or 70 years behind the times when it comes to selecting the spectral classes of stars in your fictional star system.
The only way for a writer to get around the spectral class limitations for habitable planets is to claim in the story that a highly advanced civilization terraformed a young and uninhabitable planet in the system of a young star to make it just as habitable as planet billions of years older would become. Or maybe those aliens took an older planet that was already habitable from another and older star system and mmoved it to the younger star system of the story.
Your idea that your planet could have been naurally torn from orbit in one solar ssytem, traveled through interstellar space for countless millions of years, and then been recapured into orbit in your solar system is very dubious. That would be a very rare sequence of events.
If it is possible in your story for a super advanced civilization to deliberately move a planet form one star system to another, that should happen countess millions of times more often than a planet accidentially moving from one star system to another.
And if a planet accidentially and naturally moves from one solar system to another, it should freeze up for the countless millions of years it will take to do so, killing all life on the planet. But if a superadvanced civilization can deliberately move a planet from one star ystem to another, they should have no problem keeping the planet warm and lighted while it crosses interstellar space, thus keeping life alive on the planet.
Or you can simply put your planet in orbit around a star of the proper spectral type.
Or if you don't care how hard or soft your story is, you can use any type of star you want.
Problem Two:
A planet habitable for humans can not be at just any distance from its star. Each star has a specific luminosity, and each specific luminosity has a different sized circumstellar habitable zone, where an otherwise suitable planet would have the proper temperatures for having liquid water on its surface.
Calculating the size of the circumsteller habitable zone around a star is easy in Theory. Just take the luminosoity of the star compared to that of the Sun and scale the habitable zone of the Sun up or down.
But the size of the circumstellar habitable zone of the Sun is not known with certainty.
Here is a link to a list of recent estimates of the inner or outer edges or both of the Sun's circumstellar habitable zone. Note how much they differ.
<https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates>
One way to make certain a fictional planet will be within the habitable zone of its star is to calculate the exact distance from that star that a plent would receive exactly as much radiation from the star as Earth receives from the Sun, which I call the Earth Equivalent Distance or EED.
The answer by user177107 to this question:
<https://astronomy.stackexchange.com/questions/40746/how-would-the-characteristics-of-a-habitable-planet-change-with-stars-of-differe/40758#40758>
Has a table with a list of data about differnt spectral classes of stars. The date includes the disances of planetary orbits at the EED for each listed type of star.
Note that according to Dole, the most massive star capableof having a habitable planet would be an F2V class star, with a mass about 1.4 times that of the Sun. Such a star would have an EED of 2.236 AU according to the table.
You say:
>
> Right now, I'm getting the feeling that I should place the planet from 2.something to 3 AU away from a smaller (2 solar masses) star, and 6-8.5 AU away from the larger (4 solar masses) star.
>
>
>
I assume you want the smaller star with two solar masses to more or less orbit around the larger star with 4 solar masses, and for the planet to orbit around the smaller star with 2 solar massess.
According to the table of stars I mentioned earlier, a star with 2.05 solar masses would be a class A2V star, and a luminosity 21.243 times that of the Sun, and its EED would be at 4.611 AU. Thus at a distance of 2 to 3 AU the planet would receive consideriably more radiation from the smaller star than Earth gets from the Sun, and so should be considerably hotter than Earth despite having a higher albedo. Your temperature of about minus 20 degrees C seems improbably cold even without considering the radiation the planet would get from the larger and more distant star.
Vega is a class A0Va star with a mass of about 2.135 solar masses, and a luminosity 40.12 times that of the Sun, and thus its EED should be at about 6.334 AU.
A spectral class B8V star would have a mass of 3.8 solar masses, and a B7V star would have a mass of 4.45 solar masses. So your larger star with "(4 solar masses)" would be between a B7V and a B8v star, and closer to the B8V star.
18 Tauri is listed as a B8V class star, and has a mass of 3.34 solar masses and a luminosity of about 160 times the luminosity of the Sun. Thus its EED should be at about 12.649 AU.
<https://en.wikipedia.org/wiki/18_Tauri>
Thus a planet that is 6 to 8.5 AU from a star with 4 solar masses should be hotter than Earth, no matter how high its albedo, even if it wasn't also even closer to the smaller star in the system and also heated up by that smaller star.
Problem Three.
Your planet needs to have had a stable orbit for a long time.
A planet in a binary star system can have one of two types of orbit. Exoplanets with both types of orbits have been found.
A circumbinary or P-Type orbit is when the planet orbits around both of the stars, which are much closer to each other than the planet is to them.
An S-type obit is when the planet orbits one of the stars and the other star is much farther from the planet. Your description with one star several AU farther away from the planet the plane tthan the other star indicates it is an S-Type orbit.
>
> In non-circumbinary planets, if a planet's distance to its primary exceeds about one fifth of the closest approach of the other star, orbital stability is not guaranteed.[5](https://en.wikipedia.org/wiki/18_Tauri)
>
>
>
<https://en.wikipedia.org/wiki/Habitability_of_binary_star_systems>
In your example, with the planet orbiting one star at a distance of 2 to 3 AU, and the other star being 6 to 8.5 AU distant, the ratio of distances is 2 to 4.25, less than the 5.0 minimum ratio for orbital stabiity.
According to this list, the closest known orbital distance between two stars with a planet orbiting one of them in an S-Type orbit is about 12 to 17 AU. Since the planet orbits one of the stars at a distance of about 0.7 AU, the distance ratio is about 17 to 24.
<https://en.wikipedia.org/wiki/List_of_exoplanet_extremes#Orbital_characteristics>
Problem Four
You desire that the average surface temperature of the planet is about minus 20 degrees C. That is below the freezing point of water, so there should be no liquid water on the planet and no liquid water using lifeforms. Thus photsynthesis whould never have produced an oxygen atmosphere on the planet, and it should be uninhabitable for humans.
So the colonists you mention in your question should never have colonized the planet.
Maybe they colonized the planet to mine it, and they live in pressurized buildings like in a moon base, and work in mines deep underground or in massive excavating equipment in open pit mines. Thus they should be protected from ultra violent ultraviolet rays by the roofs and walls of their buildings and by their vehicles, and by rock and/or ice when they work in the mines.
Since the air is unbreathable they will have to wear breathing gear outside, and since the climate is so cold they will have to wear very warm clothing outside. So I guess that they might as well wear protective gear when outside which covers their entire bodies to keep them warm and supply oxygen, and which also prevents all ultraviolet radiation from reaching their skin.
Problem Five.
The Earth's atmosphere keeps a lot of ultraviolet radiation from reaching the lower atmospher and the ground. Since Earth has a breathable atmosphere wiht a lot of molecular oxygen (02), some of that is converted by various processes into ozone (03), and some of that ozene forms the ozone lawyer in the upper atmosphere which blocks a lot of ultraviolet radiation from reaching the surface.
So if your planet is not so cold that it has no native life and no oxygen in the atmosphere, but instead has native life and a breathable oxygen rich atmospehere, like most planets which are colonized by humans in science fiction stories, it should have an ozone layer which block a lot of ultraviolet rays from reaching he surface.
And possibly you could find a way to change the composition of the atmosphere to block out much more ultraviolet radiation and make the planetary surface safe for your colonists.
[Answer]
**Less of a problem for dark skinned colonists.**
Constitutive high melanin levels are protective against UV damage. It is not a myth!
[The Protective Role of Melanin Against UV Damage in Human Skin](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/)
Black and Australoid persons often have high constitutive melanin levels and might be expected to have less trouble as regards exposed skin / UV damage. Maybe your colonists are such persons? Of course if your story needs some fair skinned persons they can wear stylish broad-brimmed hats when out and about.
[Answer]
M. A. Golding wrote a great answer but like me probably thought that it was supposed to be a binary system.
Regardless of your choice between the 2 to 4 solar mass stars. Your brain will just automatically adjust. From the planet looking up you would see a white star just like on earth. If you looked out over the landscape it would just look like earth. You would only notice a difference when you were comparing photo's from earth and your planet but only if you kept the camera settings the same. So for a story on planet all you would change is the amount of UV-radiation, the length of a year, and the possible lifeforms already able to have evolved on the planet.
The human eye is a remarkable thing able to perceive a lot in low light conditions compared to what our sun provides. If you have ever tried to run a high speed camera you can attest to this. Having to need lots of high powered lighting indoors while you just could move outside into the daylight to get even more light. So there shouldn't be a worry about that.
] |
[Question]
[
My story revolves around illegal fight club, one where opponents get serious and fights sometimes end in fatality. There is one problem though, I want to make more or less inclusive and appealing to many audiences. It's easy to write characters of different genders, ethnical, religious and cultural backgrounds.
However how realistic would be to have fighters older than 30 in such setting ?
In normal martial art competition, say boxing or karate 30 year old may still be able to somehow stand his/her her ground because regulations, and even get advantage because of skills if lucky. However in full on combat I believe older the combatant less are their chances.
[Answer]
**Realistic, assuming the older fighters are exceptional**
Take professional sports, for example. Sure, while it's not a blood sport (technically), there is a normal age range for players to enter the league in and a normal amount of years for any given player of any given sport at any given position - except when it comes to *really good* players. These are the kind of people who start playing professional a year or two younger than usual, play for much longer than the usual player, and can retire when they're almost a decade older than anyone else on the court and *still* are maintaining respectable numbers. An exceptional fighter could last into his thirties, or even his forties, as long as who he was smart about facing off against.
[Answer]
Muhammad Ali defended (with mixed success) his title of world champion into his mid thirties, leaving boxing at 36 (not counting to attempts at a return in the years after that). Not sure how much of his decay in skill is down to age, and how much to Parkinson's.
Looking at "softer" martial arts, Anton Geesink won olympic gold in Judo at age 30 and european champion at 33. Most succesful Judoka appear to be in their late twenties.
30 is no magic number. There have been successful athletes in the world of combat sports older than that.
Entering a combat with a real (even if small) risk of dying is stupid. However, many young people think of themselves as immortal (leading to drunk driving and all other sorts of risky behavior). I'd expect them (men, mostly) to be very present in these fights, along with a bunch of older guys trying to handle their midlife crisis and a few very scary middle aged hooligans or criminals or law enforcement people who are very dangerous and not entirely sane.
*P.S.:* As with actual existing combat sports, a big part will be metagaming: Picking only fights you are reasonably sure you win. The saying in poker is that there's a sucker at every table and if you can't see them, get up - it's you. The experience to recognize weak fighters who completely overestimate themselves, or underestimate their opponents, is important in such a setting. A fighter doesn't need to be better than everyone, they only need to be better then the people they get into fights with.
[Answer]
Sounds a little ageist to me. In a street fight age doesn't matter, its who lands the knock out punch first or does the most damage in the shortest time, in competition martial artist have to fight rounds and they are limited to certain moves and have to be within the rules.
Take away rules and rounds and the most savage or smartest fighter will win, taking out the advantage that youthful cardio levels have over other fighters.
[Answer]
I have a red belt in Shotokan Karate and Hapkido, and while my training was not full-contact, it was undertaken with the assumption that the non-contact tournaments and sparring that we engaged in was fundamentally different to real-life fighting.
That said, people are not neurologically mature until the age of around 22. In martial arts, that means that no matter how well a martial artist younger than that can execute the individual techniques, they have difficulty with improvisation: they can plan a series of actions, but when that plan ends or is interrupted, they are less able to act or react. As an adult in my 40s, I was able to defeat higher ranked juniors because of this: I could keep improvising and reacting where they could not.
Next, while older martial artists may begin to have infirmities that limit them, experience is a telling factor, and they are typically able to work around their limitations. A common martial arts trope is that of the ancient master: the wizened oldster who defeats the upstart who is in the prime of life with embarrassing ease and little effort. This trope has a sound basis in reality. As long as the oldster remains mentally and physically capable, having more experience will give them an advantage that is of more significance than a loss of raw strength as the result of age... with the result that they will shift from brute force tactics to something more subtle.
Of course, not every martial artist learns this. Some go on acting as if they are in their 20s well into their 30s and 40s... and end up with injuries that their bodies can no longer withstand. An example that my sensei gave was of a man who always blocked incoming blows squarely rather than deflecting them... and eventually broke both bones in his forearm doing so in a tournament.
So... in this fight club, I would expect there to be a predominance of younger men - those being mentally less mature and more impulsive - but there could still be a few older men, potentially up to their 60s, who *may* not be as physically strong, but who would more than make up for their lesser raw strength with greater experience.
TL:DR: Age and treachery trumps youth and enthusiasm.
[Answer]
Make the older characters supporting, i.e baristas, jockeys, coaches, or managers. There is simply no way an older guy can beat a 20 y/o fighter in his prime. In a curated match where their movesets are limited, then yes, 30-year olds not only have a chance but also a solid career. But, in an underground deathmatch, there are slim chances. Even if he wins a few times, trauma will push him out. I am 31 and I damaged my body by sleeping in the wrong position. There is no way my body can handle daily beatings. It doesn't matter how many tricks the older guy has, sheer bruising and damaged bones will either kill him or force him to retire over time.
] |
[Question]
[
So say there was a rogue gas giant about the mass of Jupiter that, unfortunately, happened to be headed directly at Earth (or at least close enough to knock it into an orbit incompatible with life). It's coming in from way out of the plane of the solar system, so it's not going to knock anything else significantly off-kilter, but Earth is in for a spell of bad luck.
In this completely hypothetical scenario, we, your benevolent alien neighbours, had absolutely nothing to do with this, but, just as a matter of curiosity, whereabouts would you probably detect this incoming gas giant, and what kind of time range would there be between detection and impact?
In other words, **at approximately what point would humanity discover a Jupiter-sized gas giant headed towards us, and how long would we have before it hit us?**
[Answer]
Lets consider how hard it would be to spot this object with visible light astronomy. This isn't *quite* the right way to go about things, but it is a start. Most things are easier to see in IR than than visible light, so my final detection distance may be out be an order of magnitude (or a bit more). Note though that whilst your rogue Jupiter *might* be warmer than your average space rock, it won't be nearly as hot or bright as the smallest and weakest stars.
---
The faintest near-earth object in [this JPL database](https://ssd.jpl.nasa.gov/sbdb_query.cgi?obj_group=neo;obj_kind=ast;obj_numbered=all;OBJ_field=0;ORB_field=0;table_format=HTML;max_rows=100;format_option=comp;c_fields=AcBhBgBjBiBnBsCkCqAi;.cgifields=format_option;.cgifields=ast_orbit_class;.cgifields=table_format;.cgifields=obj_kind;.cgifields=obj_group;.cgifields=obj_numbered;.cgifields=com_orbit_class&query=1&c_sort=AiD) is [2008 TS26](https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2008%20TS26), with an absolute magnitude of 33.2. We can [find the absolute magnitude](https://en.wikipedia.org/wiki/Absolute_magnitude#Solar_System_bodies_(H)) of Jupiter by using its [geometric albedo](https://en.wikipedia.org/wiki/Geometric_albedo) $a$ of [0.538](https://en.wikipedia.org/wiki/Bond_albedo) and a diameter in kilometres $D$ of 142984km:
$$H = 5\log\_{10}\left({1326 \over D\sqrt{a}}\right)$$
This gets us an absolute magnitude of about -9.49, which is Quite A Lot Brighter (roughly 2.543 times) that the boring rock.
2008TS26 has a semimajor axis of 1.92AU. Assuming that it is in [opposition](https://en.wikipedia.org/wiki/Bond_albedo) to the sun (a [syzygy](https://en.wikipedia.org/wiki/Proper_motion), an awesome word that is hard to use very often) it will have an apparent magnitude of 34.4, given that $$m = H + 5\log\_{10}\left({D\_{BS}D\_{BO} \over D\_0^2}\right) - 2.5\log\_{10}\left(q(\alpha)\right)$$ where $H$ is the absolute magnitude, $D\_{BS}$ is the distance from the body to the sun, $D\_{BO}$ is the distance from the body to the observer, $D\_0$ is the distance between Earth and the Sun and $q(\alpha)$ is something called the phase integral that I'm declaring to be 1 in this position.
With the same geometric relationship, we can rearrange the equation to find the equivalent distance of our rogue Jupiter where it would have the same apparent magnitude:
$$10^\frac{m - H + 2.5\log\_{10}(q(\alpha))}{5} = D\_{BS}^2 - D\_{BS}$$
Leaving us with a nice quadratic to solve, giving us a $D\_{BS}$ of ~24495AU, or about .387 lightyears. You haven't actually told us how fast this rogue Jupiter is travelling. Barnard's Star has the highest [proper motion](https://en.wikipedia.org/wiki/Proper_motion) of nearby stars, as it is going at about 142km/s relative to us. If your rogue Jupiter had a similar speed, it would take 817 years to reach us.
(*edit for Alexander*: with a more pessimistic detection magnitude of 20, the detection distance becomes ~1190AU, and the transit time at 142km/s would be 40 years)
It is lucky it will take so long, because finding such cool and faint objects requires some serious hardware and dedicated telescope time. Something like WISE ([Wide-field Infrared Survey Explorer](https://en.wikipedia.org/wiki/Wide-field_Infrared_Survey_Explorer)), a satellite, whose main mission ran for just 10 months before the coolant ran out, or 2MASS ([Two Micron All-Sky Survey](https://en.wikipedia.org/wiki/2MASS)) which used ground-based telescopes over a four year period would be needed, at the very least.
The most difficult bit would be spotting that the object was close and getting closer... if we were meeting it head on, it would have no proper motion and so traditional techniques for spotting nearby bodies wouldn't work and it could take multiple surveys over a long period of time to spot that it was getting brighter. If it were hitting us as right-angles to the Sun's trajectory, it would have some proper motion that would appear to reduce as time went on and it should become clear that it was on a collision course with us given a bit of extra attention.
>
> It's coming in from way out of the plane of the solar system, so it's not going to knock anything else significantly off-kilter,
>
>
>
You can't just fling a Jupiter-mass through the inner system and assume that everything but Earth is going to be just A-OK. It is going to have a non-trivial effect on the orbits of all the inner worlds and the asteroid belt. How disruptive this would be I couldn't say, so you'll have to run it through a gravity simulator and see for yourself.
---
With regards to Rob's answer and brown dwarf stars, they're not quite comparable to Jupiter-type large gas giants. A binary brown dwarf system has been discovered a mere 6.5 lightyears away, in the form of [Luhman 16](https://en.wikipedia.org/wiki/Luhman_16). The stars might not be hot hydrogen-fusing things like most stars are, but they still have quite high surface temperatures... over 1000K. Jupiter, by comparison, is a mere 165K, and at least *some* of that will be contributed by solar heating (though admittedly not very much). The [Stefan-Boltzmann law](https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law) shows that radiated power per unit area from a black body is proportional to the fourth power of the object's temperature, which means that 1000K brown dwarf is ~1350 times more powerful an emitter as a 165K gas giant *of the same size* (and warmer brown dwarfs will be slightly larger, too, and so emit a higher total power). Brown dwarfs may not be much larger than Jupiter, but they can be much hotter and therefore much easier to spot with IR telescopes.
I suspect my .387ly estimate is a little pessimistic, and whilst I wouldn't be too surprised to be out by an order of magnitude, being out by *two* would be surprising for such a small and relatively cold object.
[Answer]
I expect we could see it from along way away. If we look at brown dwarfs, which have higher masses than Jupiter but cruically will have about the same temperature, then looking in the infra red we have seen brown dwarfs out to a few tens of light years (restricting ourselfs to the t dwarfs which are the closest match to a Jupiter) <https://en.m.wikipedia.org/wiki/List_of_brown_dwarfs>
The bigger issue will be if we have a telescope pointing at the right place at the right time. We have only just discovered a brown dwarf practically next door (<https://en.m.wikipedia.org/wiki/WISE_J0521%2B1025>) at 5 light years away simply because space is big and we have limited telescope time.
] |
[Question]
[
I was reading some questions on Quora and I found [this claim:](https://www.quora.com/What-would-happen-if-rainforests-disappeared/answer/Paul-Noel-5)
>
> The polar regions have a very odd reason for them to have so much oxygen production. You see the Polar aurora run day and night in the UV band. They are about 600 watts per square meter day and night. You don’t see it because you don’t see UV. This hits the sea and causes a bloom of life that makes the biggest fish catches and largest sea animals including whales. This is about equal to 1/2 strength noon sun.
>
>
>
One thing I hate about Quora is how people there don't usually back what they say. In this case I could find nothing to back that claim. So I decided to file it as "probably not true" in my mind for the time being, but that would be nice concept for a fictional world. One of the worlds I am working on could actually benefit from such a feature.
Supposing an alternate Earth where emissions coming from the Sun were much more massive or constant. Think Carrington Event, only constant instead of lasting only a few hours. That would broaden the range of latitudes where auroras happen. Could photosynthesizing life in this world, specially marine algae, evolve to take advantage of the constant auroras?
I don't care how much different or alien the ecosystems of the world would be, that's out of scope. I'm just curious about the prospect of life harvesting energy from auroras.
[Answer]
It might be possible.
We've known for around a century ([since at least 1933](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2141274/)) that ultraviolet light can inhibit photosynthesis and possibly damage photosynthetic mechanisms inside an organism. Phytoplankton in particular [have been recent targets of this sort of research](https://www.sciencedirect.com/science/article/pii/1011134495072454), and it's been shown that their photosynthetic systems are negatively impacted by ultraviolet photons - [even more so in the case of shorter wavelengths of light](https://www.sciencedirect.com/science/article/abs/pii/S0098847209001580) (think $\sim$300 nm). Presumably, with a strong, continuous source of ultraviolet radiation, typical photosynthetic organisms like the ones we have on Earth would be quickly killed off.
Now, it's possible that in your world, organisms could adapt to solve the problem of ultraviolet light. As [one](https://www.sciencedirect.com/science/article/abs/pii/S0098847209001580) of those two phytoplankton studies found,
>
> As the cells were grown during long-term exposures to solar radiation, the ratios of repair to UV-related damage increased, indicating their acclimation to UV.
>
>
>
Therefore, if the organisms are exposed to low levels of ultraviolet radiation for millions of years, they will presumably develop a significant degree of tolerance. A way you could make this even simpler would be to replace the Sun with a star that's slightly hotter - say, maybe 7,000 or 8,000 Kelvin, which you might see on an F-type star. That star would emit more ultraviolet light (doing [about 2.5 to 7.1 times as much damage to DNA as the Sun does](https://www.space.com/25716-alien-life-hotter-stars.html)), and so any organisms developing on a planet around it would be more likely to adapt to the high-energy photons, even if the aurora is not the main source of light for photosynthesis. Of course, there's still going to be DNA damage, regardless - a strike against using ultraviolet light from an aurora at all.
Let's talk about auroral brightness. The best source I was able to find was the [Australian Government Bureau of Meteorology](http://www.sws.bom.gov.au/Educational/1/1/8). They note that in some very rare cases, auroras have emitted fluxes of 1000 [kilorayleigh](https://en.wikipedia.org/wiki/Rayleigh_(unit)) (a unit of photon flux); they describe an aurora like this as
>
> Bright as the full moon. Casts shadows. Very rare.
>
>
>
Of course, [the Moon is about 400,000 times dimmer than the Sun](https://en.wikipedia.org/wiki/Apparent_magnitude#Example:_Sun_and_Moon), so you would presumably need continuous, intense stellar activity to create an aurora that could come within even an order of magnitude of the Sun's apparent brightness.
Could something like that happen? Perhaps. Some Sun-like stars are known to emit [superflares](https://en.wikipedia.org/wiki/Superflare), which release large amounts of energy on timescales of minutes to days. They've been observed in cool F stars, like [Omicron Aquilae](https://en.wikipedia.org/wiki/Omicron_Aquilae) and [5 Serpentis](https://en.wikipedia.org/wiki/5_Serpentis). It's not out of the question that you could have a hot superflare star that would emit enough energy and ultraviolet light to create the scenario you're looking for. The one problem I can find with superflares is that they only tend to happen once every thousand years or so; perhaps your star could get around this by emitting low-energy superflares more frequently.
[Answer]
>
> They are about 600 watts per square meter day and night
>
>
>
That is a frankly *terrifying* amount of UV. Forget suntans, think germicidal lamps and epidemic malignant melanomas. The relevant [wikipedia article](https://en.wikipedia.org/wiki/Sunlight#Measurement) suggests that about 3-5% of sunlight hitting the Earth's surface can be classified as UV (ie. wavelength below 400nm), and we get about $1kW/m^2$ of solar irradiance at the equator. This means your 600W of UV (presumably they meant "per square metre") is more than 10 times more UV than you might expect to get on the equator, with clear skies, at midday. Those pale nordic people? They'd be *incinerated*.
Auroras form quite high up in the atmosphere... at least 80km, and often more. Over 80% of the mass of the atmosphere is found below 20km (including almost all of its ozone) and that's a substantial amount of UV attenuation there. To get 600W at the surface, you're going to need *kilowatts* of UV at aurora height. I couldn't tell you what sort of particle flux you'd need to generate that much UV, but it sounds like it would ablate the atmosphere in relatively short timescales... certainly shorter than the amount of time you might have to wait for life to evolve.
>
> if the organisms are exposed to low levels of ultraviolet radiation for millions of years, they would presumably develop a significant degree of tolerance
>
>
>
I think after a few million years of being exposed to atmosphere stripping germicidal radiation like this, what they will mostly be needing is a tolerance to *vacuum*.
>
> This hits the sea and causes a bloom of life that makes the biggest fish catches and largest sea animals including whales
>
>
>
You get lots of whales and fish where you find lots of their food. You find a lot of fish food in the arctic due to [upwelling](https://en.wikipedia.org/wiki/Upwelling#Coastal) of nutrient-rich water feeding vast phytoplankton blooms.
] |
[Question]
[
I am imagining a world where an astronomical event occurs, like Earth collides with a comet, and humanity is all but wiped out. In their desperate attempt to recover, humans enter a form of stone age. Most of the existing life forms are still there, though also decimated by the event. Modern humans apply their existing knowledge to set out hunting, gathering, farming, and ranching. But something is different; the bioavailability of iron in all the Earth's arable soil is diminished and consequently becomes a highly coveted resource. The entire planet is anemic. The drive for iron-rich foods drives humans crazy. They drink blood from their dead and hunt each other for it. New species with copper based blood like the horseshoe crab rise to prominence.
What kind of event might have led to these conditions?
[Answer]
**Iron is irreversibly chelated into non-degradable molecules.**
Consider PCBs or polychlorinated biphenyls.
<https://en.wikipedia.org/wiki/Polychlorinated_biphenyl>
These were useful industrial chemicals, but unfortunately persist indefinitely in the environment. Somehow they also cause health problems, which I would not expect for a biologically indestructible molecule but there you are.
The earth is showered with PCB-like indestructible chemicals which have the property of being extremely iron avid. Perhaps they are like PCBs but contain sulfur? The provenance of these chelators is up to the author - maybe space molecules, or products of an alien civilization. Or perhaps like PCBS they were produced in great quantities on earth (bioengineered crops?) before their troublesome properties became known.
In any case: a *lot* of that stuff, because there is a lot of iron in the crust. The indestructible chelator molecules mop up the iron and keep it. Maybe these chelators form rusty looking blobs that people and animals eat and then excrete unchanged.
[Answer]
Iron is rather abundant in solid land, but no so much in significant parts of the ocean. Furthermore, plants have difficulty absorbing iron when soil pH is too high, has too much clay, or is overly wet ([source](https://www.gardeningknowhow.com/plant-problems/environmental/leaf-chlorosis-and-iron.htm)). To make matters worse, high amounts of plant particles or manure (which would likely be a rudimentary attempt at fertilization post-apocalypse) can [also cause iron deficiency](https://www.agweb.com/article/understanding-iron-naa-darrell-smith/).
When you put all this together, a giant comet slamming into the ocean could cause a significant redistribution of water across most inhabitable land. In the right conditions a higher pH-soil or more clay-like soil might cover a significant part of the earth's crust, making stone-age style soil aration difficult, not to mention unlikely to penetrate deep enough for plants to be able to reach more iron-rich soil. Just enough clay and acidity, mixed with rudimentary farming, and plants will suffer from iron deficiency, which in turn means most humans would as well.
It all comes down to what was in that comet - anything on/in the comet that can rice the pH level of dirt or cause some type of residue that alters pH in soil would do the trick.
As iron deficiency gets worse, it can cause ["unusual cravings for non-nutritive substances, such as ice, dirt or starch"](https://www.mayoclinic.org/diseases-conditions/iron-deficiency-anemia/symptoms-causes/syc-20355034) can occur. Although drinking blood is not commonly associated with iron deficiency, I suppose iron deficiency plus a sudden restriction of the gene pool (read: inbreeding) would be at least somewhat believable.
[Answer]
A miracle, or Alien Space Bats.
There's nothing regarding an impact that would be survivable (as per the requirements of your scenario) that would significantly alter the chemical composition of the crust on a planetary scale. It might *add* a detectable amount of something, but not remove it. You're not going to get your vampires that way.
[Answer]
Iron really likes Oxygen to form rust. From geology we're know that the oceans once held far larger quantities of iron, but that when photosynthesis evolved the iron turned to rust and precipitated. I'd there were more O2 in the atmosphere, more iron would form rust, and less would remain bioavailable.
If the event caused the O2 level to significantly increase, the would be really ferocious fires and less iron.
[Answer]
An nonnative invasive alien fungus grows over the entire surface of the earth. It proliferates and stockpiles accessible iron into mycorrhizae attached to the mycelium 100s of meters below the earth's surface, and then goes dormant for centuries. The fungus is not visible to the naked eye, or perhaps it is but is resistant to any efforts to exterminate it. Even if people know it's below the Earth's surface, efforts to mine or sequester it are fruitless.
[Answer]
You can't eat pure iron, it will kill you. Plants and bacteria are able to take iron oxides from the substrate and form organic and inorganic complexes that animals may then ingest.
So your iron intake is coming from either plants, or animals that ate those plants. In the event of an impact that fills the atmosphere with dust and blocks sunlight, most plants would die. This has happened before. But in that case, it's not just iron that animals would be missing.
In our case, we might thrive for decades with dietary supplements scavenged from factories and supermarkets. But at some point post-apocalyptic societies without access to silos and other long-term seed-storage solutions would be out of useful plants to grow, and then they would be in dietary trouble.
] |
[Question]
[
**Background**
Hi all, I'm revisiting my musings on plausibly strengthening the human skeleton to better withstand the stresses of combat, melee in particular. If y'all don't care about background, skip to "The Question" two paragraphs below.
In my setting, space marines (in the sense of soldiers who board space-/star-ships, not the Warhammer kind) have always preferred melee combat during boarding actions. In the early days of space-flight, people were still using kinetic weapons to defend themselves, and this practice remains widespread planetside. Aboard starships, however, it was quickly discovered that the bulkheads separating the warring marines and the Void weren't quite up to the challenge of shards of metal flying at obscene speeds.
Rather than wait for starship manufacturers to catch up to this, many pirate factions switched to melee weapons such as swords, spears and shields. These shields are the key: being made of a MacGuffinite alloy (haven't gotten around to naming it yet), it is able to stop most kinetic small-arms fire with very minimal damage to the user. This lead to guard crews and eventually the Space Marine Corps to adopt similar weapons. Nowadays, an advanced and ancient race of humans from another planet has decided for various reasons to adapt the biology of their marines to this new melee combat, so as to not need the obscenely intricate and finnicky powered armor that other factions have taken to using.
**The Question**
Now, I'm going to address changes to the overall structure (e.g. bone shape, placement, etc.) in another question. For this one, I'm more concerned with the materials, composition, and structure of the bones and ligaments themselves. First off, I've seen somewhere that someone suggested coating the bones in a cartilage membrane. Now, what if we took that to the next level, and interwove that with carbon fiber? Also, could we actually embed a sort of carbon-fiber "rebar" within the bone itself, and potentially even include a core made of more rigid CF (sorta like that stuff new fancy bikes are made of)? This leads to another concern: is it plausible that there are certain enzymes within the cells of the skeletal system that are able to synthesize and lay down this carbon fiber matrix, a sort of carbon-fibrase? As for ligaments, would making them out of pure carbon fiber be better than a mix of carbon fiber and normal cartilage, and would either of those be better than just the cartilage as it was before messing with it?
Alternatively, might another material be preferred over carbon fiber in this context, either for mechanical or chemical reasons? I was thinking carbon fiber because, well, we're carbon based life forms after all, and I reckon that the materials to make it wouldn't exactly be hard to come across in the diet. Plus, my understanding is its strength-to-weight ratio is outstanding compared to bone. Note also, I'm wanting this metahuman to be much stronger than a normal human too, so that's another reason to strengthen his skeleton to better cope with the increased stresses exerted by his musculature.
Thanks in advance for your answers!
[Answer]
## Kevlar
Kevlar would probably be a better choice of reinforcing fibre: It's almost as strong per weight, and more **shock resistant**. And what you want to avoid at all cost is a fracture, so shock resistance is important.
The mechanism would be mostly the same, though.
## Implants
Absolutely **not, unless** you are switching out the entire bones and ligaments at a time. If you try putting plates or bars or anything of the sort onto the bones, then it's just the places where they are fixed which will break instead, and the artificial part is likely to make the injury worse, like a blunt knife being moved around you. The following assumes you want to make the body grow the enhancements by itself, but if you want to go with implants you can fabricate replacements bones and ligaments and muscles outside the body and implant them - but the body growing them by itself, that could have somewhat plausibly appeared during **evolution**. Replacing so much of a body with artificially grown stuff requires an extremely high **technology level**.
## How to arrange the fibers
If the body could grow carbon fibre, it would use the bones as they are now (or from a slightly different material) as the matrix which surrounds individual carbon fibres and glues them together. The carbon fibres could either cross through the entire cross section or just an outer ring, and with respect to the length of the bone would need to be straight or helix-like with varying steepness depending on which bone and how it is usually stressed.
## How to create the bone-fiber composite
I'm not sure how bones are usually grown, but it would be most plausible to grow carbon fibre like hairs and at the same rate grow bone matrix surrounding the fibres. The thing growing the carbon "hairs" would need to be able to rotate to produce the mentioned helixes that are optimal for some loads.
Or if you start with a thin bone, then the "hair" would need to be grown along the surface of the bone at the same time as a new outer layer of bone. This sounds more complicated, but maybe it's possible to move the follicles growing the carbon fibre.
## How to repair after a fracture
Either through the very hard process of reconnecting the ends of every ripped fibre, or more realistically by adding new fibres on the outside, so the bone would become noticeably thicker than before for the same strength.
## Tendons and muscles
After you have reinforced the bones, the tendons and muscles need to be reinforced too or they will be the weak point. In principle that can work the same, only that for a flexible material where only tensile strength matters the fibers aren't interlinked by the matrix and thus fixed rigidly but are embedded in a flexible material (for example the same material as in real tendons and muscles).
## Why I think you can just assume the existence of fiber producing follicles
Now, at the beginning I made the assumption that the body can grow carbon fibre (if it can do that, then like a hair, everything else is comparably very difficult). In industry, this is extremely energy intensive and uses extremely high temperatures. There is obviously no known organism which can do that with a sensible amount of energy at low temperature (otherwise carbon fibre would be harvested from it), but there is no physical or chemical reason such an organism couldn't exist. So you can just assume that if you want, and the explanations I gave above should be plenty to explain some of the mechanism to the reader without giving them a lecture on chemistry and biology.
[Answer]
# Reality Check
(WARNING! Do not look at the third image if you are squeamish.)
***Probably not.*** Implants are, obviously, a thing, but the realities of putting them inside the body at the very least will preclude their use. Bones are covered by a layer of tissue called periosteum. A main function is the residence of osteoblasts, which form new bone. It's not a very tough layer of tissue, so interweaving it with carbon fibre won't do much good.
You'd want to actually strengthen the bone itself. Carbon fibre is a reasonable choice, and is already in surgical use, so the technology is sound. So that part passes the *reality check* test. Other materials that have been used are titanium and stainless steel. Two ways present themselves, but neither are pretty.
**Plates**
One is to stiffen pre-selected bones with plates. We already stabilise fractures with plates. What you're looking to do is stiffen bones to prevent fractures.
[](https://i.stack.imgur.com/CEc9r.png)
**Rods**
Alternatively, you can ream out the medullary canal and shove a metal rod down the inside of the bone.
[](https://i.stack.imgur.com/WyNSp.jpg)
Similar plates & rods exist for the wrist, thighs & calves, too. Basically, anywhere on the body you want to put a plate, you can.
**Pros and Cons**
On the positive side, carbon fibre is already used as a surgical implant material. The first picture above appears to be a carbon fibre composite plate.
On the negative side, anyone who undergoes this treatment is looking at multiple initial surgeries (at least *eight to ten* procedures to plate the major bones alone) plus regimens of physical therapy to follow each procedure.
If you wish to also plate the cranium, mandible, sternum & ribs, that can be done, but, again, at a very slow rate and with long recovery times. You could be looking at two to three years worth of procedures, recovery times & therapy. Add in the cost per procedure plus inadvertent incidents (infection being the most likely; rejection; hardware issues (screws do come loose); death and I just don't think you can justify the cost with the minimal protection this kind of process can afford. A strong hit from a melee weapon can still break or fracture bone, even when strengthened. The plate itself can be damages. The hardware --- screws --- can be knocked loose, causing further injury.
Admittedly, you *might* have some built in stabilisation with such implants, but your soldier will have still have to undergo corrective procedures all the same, even after a relatively easy battle.
**Rationale**
Basically, you want to do this on multiple parts of your soldiers' bodies. DO NOT LOOK IF YOU ARE SQUEAMISH!!
I personally would not be on board with this. This part does **not** pass the *reality check* test.
>
> [](https://i.stack.imgur.com/SILYs.jpg)
>
>
>
**Another Option**
You probably won't like this one, but since you're looking to increase the strength of your soldiers, just give them armour! Lightweight carbon fibre / composite plates (for melee weapons) in conjunction with kevlar type armour might prove a better option than messing around with surgery.
[Answer]
If you're dealing with space boarding actions in the far future, you're already talking science so advanced that the standard version of science-fiction magic, aka "nanotech", would work. Especially if you made it quasi-realistic; nanotech enhancement of bone by building up supporting carbon-fibre gradually, but taking time to do it in controlled conditions where the nanotech could be controlled remotely and issues such as waste heat (which tends to be forgotten when nanotech is involved) can be controlled.
[Answer]
I'll give you an option that I'm currently working on my story.
There's this disease called Hemochromatosis, which leads to a higher content of iron on the human body. It's not beneficial though, you got severe damage to you body because of that, but with some creativity we can create a scenario where it's an enhancement.
I, for instance, made my society go through a lot of generations, each one mutating a little bit and through natural selection the best fit for that environment survived. He survived because his body had enzymes that linked Iron to carbon(readily available for us) forming Steel alloy in different parts of the body. You wouldn't suffer the side effects of the disease because all the iron is trapped and now you have a super body.
You could do that using genetic modifications, as I see it's a high tech environment, or anything you prefer. Harder and yet flexible alloy for the bones, ligaments of steel wire and even some steel skin that could withstand weak impacts.
] |
[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/114403/edit).
Closed 5 years ago.
[Improve this question](/posts/114403/edit)
I remember once in history class, we were taught about the whole stigma that during the United States early years, European Americans would take Native American lands and put them in preserves. I then joked on the idea if an alien species for whatever reason, would just come to earth and relocate humanity as a form of historical Karma. Well turns out I wasn't the only person who would think of this idea, and that's exactly what happened within the plot of the movie *Home*
In the Movie, for a ridiculous reason, an alien species known as the boov decide to relocate ALL of humanity to preserves located in Australia in a place known as humanstown. there each family would be given basic ownership of houses grouped up in circular batches.(Probably to make sure different cultures would not be too off to one another). And all the humans were given an adequate supply of basic needs and entertainment. In this "Town" The people don't have to work on any jobs, need to be paid, worry about civil protection, or have to farm their own food, It's all done by the aliens. Information like news and what's going on behind other batches more likely would not be shared publicly. All humans within the preserve are told that they will be living in these preserves for forever, and that moving to different other preserves is either physically impossible or illegal. Meanwhile the rest of the boov take all of human housing and property and live in it themselves.
As to ensure enforcement, the boov would more likely do everything they can to distract humanity from thinking about there past home, and consider acts of disrespect or hostility as "mistakes". and if seven mistakes are made to a specific human. They could simply erase them, or "poof" them off of existence. If this rule of enforcement was done to themselves, it's more likely they would do the same to other species.
Here is an image of Humanstown just to get an idea of scale.
[](https://i.stack.imgur.com/9iir3.jpg)
by the end of the movie, most of the the aliens decided to leave the earth and live on the moon instead, and relocate humanity again back to their initial homes.
So the question is, how would different Nationalities, Religions and different groups of people REALLY react in such a situation if they were sent to these centers? and if they did bring all 7+ billion people back to their exact homes, would all the world's nations, businesses and jobs be able to function back into their pre-alien selves? If so, how long would it take? would the world really accept these aliens to their own societies? If not, would they care if they stayed on the moon and agreed not to interfere with them again? Or would they simply in fear reverse engineer there technology and eventually go to war with them?
A Few Handwaves
1. No biological or language barriers. They change themselves to fit earth and vaccinate all of humanity and its wildlife by gassing the atmosphere.
2. The World's military doesn't detect them on time to stop them or warn anyone about the invasion.
3. Somehow, they have enough supplies and labor to support ALL human needs and a few wants. The best way that this could possibly be justified is that aliens have been living on a moon sized interstellar ship for several years, so they more likely have the technology to easily create food in huge amounts to sustain the population, same can go for creating 'Human food'.
4. The Aliens catch ALL of humanity in about an hour. same amount of time it took for them to bring them back.
The Scenario doesn't really have to go like it is in the film.
A situation like this would not even be close to being something realistically aliens would want to do to a primitive civilization. Even if they had a freakish desire to take Earth-land, they could've easily put them all in simulations, though it is interesting that they at least CARE about the life of humans unlike most fictional aliens in film.
But still, it's interesting to see how a situation like this could go down.
[Answer]
**If you hand wave everything, like how to feed them, how to deal with sewer and garbage for just one week, how to water them, and all the supporting infrastructure needed for all that (the biggest of which is transportation, which needs oil and metal and machinery and the beat goes on and on and on...)...**
And that's a LOT to swallow, BTW.
* The psycological scaring caused by the overwhelming evidence that we are neither alone in the universe nor in the slightest way capable of defending ourselves from our new neighbors would cause a fair number of people to curl up on their sofas and either sicken or die from starvation.
* The psycological scaring caused by FoxNews, CNN, and every other news service subsequently broadcasting every conceivable aspect of the most "affecting" event ever to have been and ever to be in human history would cause more people to curl up on their sofas to sicken or die. You can bet the news programs wouldn't let the subject go for weeks if not months.
* I'm not at all sure what the Australians would do if the aliens failed to clean up after themselves. A substantial portion of their nation and continent would suddenly no longer be in its natural state. I could imagine that having environmental and ecological consequences, afecting everything from wildlife to the weather. Not to mention you'd have criminals claiming housing groups for their syndicates. Australia would become the outback in a way neither man nor God ever intended.
* Anybody still sane enough to think would panic, demanding answers and assurances from govenments world-wide. This would lead to two things (at least). (a) Defense spending on a scale that would make the most Illuminati-crazed conspiracy nut's head explode and (b) people just like the people the Illuminati-crazed conspiracy nuts are afraid of stepping into positions of power to take personal advantage of the world-wide instability. It would be a sociopath's dream. And we're talking real end-of-the-world stuff here, cats and dogs living together... mass hysteria! (I love that movie...) By the time people started to realize their psyches were no longer in immediate danger (weeks, at least), the economic and political damage would be done — and it would be very hard to change.
* The really hopeful and good people among us hope and believe that in situations like this humanity will come together for mutual self-preservation, that it will erase national boundaries, dissolve racial insecurities, put a chicken in every pot, and stop the spread of gonorreah among teenagers. What's more likely to happen is just the opposite. Debilitating panic of all kinds in the days following this traumatic event will cause instability that could and probably would rip nations apart. I could easily imagine the nation of Northern California kicking out all the Jews and promising "real change" while their people starve, all the while not telling the population there's no where near enough condoms for all the panic-justified teens. But at least there will be enough Marijuana to keep the population relatively calm — for medical reasons.
* The population boom nine months later would be tragic in biblical proportions and would utterly overwhelm any national social-security-style protection in just under 70 years.
* Religion might see its greatest boon in history, maybe. This one's a toughie. Aliens would disprove most if not all religions. But if you qualify as "religion" any philosophy meant to offer stability and comfort no matter what the cost to those bound together so, then you might see the single largest increase in new "religions" in human history. And you can bet some of them would be more than willing to slough off the mortal coil to get them to the lunar surface as angels of light to join the welcoming aliens who did all this for our good, anyway. The news media would have another month's worth of fodder and the Pastafarian membership would shrink for the first time in its history. (Which is an unbelievably important issue since Pastafarianism's revelation that the lack of pirates is causing global warming will no longer keep alligators from protecting U.S. citizens from terrorist attacks. You know they're doing their job because there havn't been any recent attacks. I'm sure the government will hand me grant money to prove that I'm right.)
* Which means, of course, that defense businesses would boom, most luxury business would die, city infrastructure would suffer terribly due to employment shortages and the over-militarized *Purge*-watching public will think the coolest thing possible just happened.
The chaos and panic caused by so large an event over so short a period of time would be absolutely breathtaking.
*Of course, I could be completely wrong.*
[Answer]
## You are asking two questions:
1. How do humans react to knowing that an Alien race exists, lives nearby, and is so powerful that they can do anything to humanity at a whim and no one can stop them?
2. How do humans react to being forcefully relocated for reasons they don't understand, then afterwards are allowed to go home.
*To answer question 1.*
If you are in a scenario where your very survival depends on someone else and all the cards are in their hands and not yours, then what would a normal human being do? I think the answer is grovel. The humans will probably do whatever it takes to make the aliens happy because they don't want to be annihilated.
What will happen to the religions of the world? This will vary. I am sure someone will try to and explain that the aliens are really somehow part of god's plan, etc. Not much may change here except some really roundabout thinking to explain how the aliens fit into the current belief system.
*To answer question 2.*
The humans probably feel the same way that the Japanese in the USA did after World War 2. Angry, untrusting, offended, and like a foreigner in their own country, etc.
[Answer]
# Basically everything about humanity would change
This is A Lot if new information for our puny human brains to take in so quickly. We just found out that
1: We are not alone, and aliens are 100% facts
2: We were just moved into a tiny area, so that aliens could live in our home
3: Then we go back to our homes
The psychological scarring would be immense, religions central belief structures would fall apart in etc. Programs like CETI would get huge bumps in funding, along with space exploration. Our species would be forever changed
] |
[Question]
[
The specific situation is the tech in the *Battletech* universe. The Kearny-Fuchida hyperdrives are jump drives that can travel instantaneously up to thirty light years - being deposited (usually) at the zenith or nadir jump point of a star system (a spot of minimum gravity several AU from the planets).
The result is that it takes minutes to travel from star system to star system a week-ish to recharge the jump drive, but weeks to months to actually reach a planet.
This gives the *BT* universe its character - that you don't zip about in a ship hopping from battle to battle. But I wonder about the way combat has been portrayed. If I remember, wars happen mostly along borders. Is that realistic? What strategies would emerge with this model of space travel?
[Answer]
**Graduation Day**
Have a look at Vernor Vinge's novels using bobble technology.
The thing is if space travel becomes so easy and ubiquitous, and anywhere within 30 light year ranges to which then you can just jump another 30 and so on and so on - what will happen?
Suddenly everyone will just jump away, and the human race will disperse radically, there will be no-one left on Earth, and you won't be able to find anyone else. Like the 'technological singularity', an idea Vinge coined, 'Graduation Day' is basically a singularity in which everyone just leaves and disperses so much like gas escaping a balloon.
The actual likely scenario ironically may be that there are no borders at all.
[Answer]
* Each system will have a "border" which can, in principle, be defended. Why keep all your defenses in the inner system, allowing the invader to do all sorts of mischief, if you can send strong detachments to the jump points instead?
(Fear of defeat in detail might be one reason.)
* If jump points are "paired" and/or jump lines are relatively few, you might get borders for interstellar polities. If somebody owns both/all ends of a jump line, it is a calculated risk to send only light forces to that jump point. After all, anybody who comes in must have come from one of your systems.
If ships can jump to *any* star within 30 lightyears, then it is not feasible to defend or even picket every brown dwarf that could be used as a stepping stone. So you still have to defend the jump points of your systems.
Are you aware of Niven and Pournelle's *Mote in God's Eye*? Or Weber and White's Starfire books? Warfare along a "jump line" network. With non-paired jump points, it is more like the "island hopping" naval campaign in WWII. Each island was a very hard and expensive target, but moving between them was cheap.
[Answer]
Some thoughts that come to mind, nothing comprehensive but here's what I've got:
* Under those restraints the "border" is actually a zone roughly 60 light years across in which the government that is theoretically in control isn't actually going to want to build anything too vital in the way of arms manufacturing or other war materials, shipyards etc... and in which civilians aren't going to feel hugely safe at the best of times. In reality while there's peace, even uneasy peace, in the area the border zone will be exploited and colonised but once the balloon goes up it will quickly become a largely empty "buffer zone" as the civilians up sticks and government facilities are destroyed and aren't considered worth replacing, and/or it isn't safe to try.
* If the jump points into systems are stable they'll be heavily mined as systems are abandoned to prevent empty star systems being exploited as stepping off points for invasion fleets. If the jump points aren't stable enough for mines then the systems will be seeded throughout with long range automated weapons with the same goal. Depending on the available technology automated weapons manufacturing may be set up to guarantee continued interdiction of particular systems, especially those that grant close access to important targets.
* It will likely be considered worthwhile, and may actually be depending on circumstances, to put patrols into the systems that are most strategically placed as stepping off sites to raid important infrastructure.
* In important systems, those with strategic resources and infrastructure, close to the border that remain occupied most of the available interdiction capabilities are going to be aimed at keeping a lid on the stable incoming jump points in case of a breakthrough attack and important targets are going to be heavily hardened to resist attack until help can arrive. Such systems are going to have heavy fleets on continuous patrol and rotation, and those fleets will raid back across the border where possible as well.
* Systems without strategic resources that are close to the border are going to look more like the systems in the buffer zone as their civilian populations thin out under the threat of breakthrough attacks, this will make the border very "lumpy" as the only properly occupied systems near it are the military ones. These semi-abandoned systems are going to be quite attractive to people disaffected with the government that want to get away and set something up elsewhere.
* Far from the border zone the war won't be a real thing to most people and as the war continues less and less military hardware is going to be evident as you get further from the border, there's not a lot of point interdicting systems that can't be directly attacked. There will still be warships but largely they'll be going from shipyards in the interior out to the border with a few smaller ships stationed in-system as much for customs interception and search and rescue work as anything else.
* Pirates, political dissidents, separatists, smugglers, and companies who want "alternative resource channels" are going to dearly love that wide swath of abandoned and thinly patrolled space.
* In-system operations, and the tactics thereof, are controlled more by the relative speed and maneuver capabilities of the fleets involved than by any other single factor.
Have a look at Jack Campbell's *[Lost Fleet](https://en.wikipedia.org/wiki/The_Lost_Fleet)*, he discusses/demonstrates the limitations of in-system combat and the logistics of wars fought under similar circumstances to the *Battletech* system, not the same but close enough that there's some insights there that may help.
[Answer]
If you're sticking right with the system Battletech has, I think they're pretty spot on.
What would allow wars to spread significantly inside each powers territory? You have a fairly limited jump range (60 LY at best *if* you have Lithium Fusion batteries). Any power is going to have the Zenith and Nadir points monitored, at the least. Bigger systems will have recharge/defense stations, and defense fleets. So while you may be able to get through a few systems, with a small fleet, you're not taking the fight all the way to Tharkad without fighting in the majority of systems in between.
So what you end up with, is more of what were familiar with. Technically, the US could slip troops up well into Canada, but in small numbers. There's no solid border, its not *completely* secured and defended, and the majority of borders aren't. Yet when we fight on Terra, it's mostly at the borders. Sure we can get some troops behind enemy lines, but not many.
[Answer]
On a more tactical scale, the appropriate strategy for attacking a system would be to divide your attacking fleet(s) and come at the system from multiple axis, and at different times. Since you can jump across interstellar distances quickly but need to slog through inertial space it become easy to overwhelm defenders and get them out of position. They see an incursion and trundle the fleet to respond, but then another attacker appears in a different quadrant.
The defender needs to either move the fleet to intercept the new threat (with a consequent use of energy, reaction mass and other supplies), or dispatch the reserves. At some point either the attacker packs up and jumps out (leaving the defending fleet still near the orbit of Jupiter) or the defender runs out of resources, and a very small attacking force out of the total englobing force moves in and forces the surrender of the home planet/base.
This leads to a resource maximization strategy, where the defenders try to flood the system with as many ships or fighting platforms as possible to cover all the different approaches. This really doesn't work very well since the ships will be much smaller and less capable, and if the attacker is working the same strategy, they will be able to pump many, many more ships into the battle.
This may end up resembling fighting the Pacific theatre with swarms of PT boats rather than battleship and carrier task forces. While a task force is far more powerful, they simply cannot be everywhere at once, and given the right conditions, a swarm attack by PT boats could even be very dangerous. If the defender can arrange to lure the attacker into "restricted" space (like the Hill sphere of a planet), they may even have sufficient advantage with swarms of PT boats to defeat carrier battle groups. On the offensive, you would need to take short hops, fortify any system you manage to capture and turn its productive capabilities to expand the numbers of PT boats you have, and supporting the ability of the fleet to continue operations.
The "Grand Strategy" would then be building your industrial base, working in short "steps", building alliances to focus your resources on one enemy at a time and being able to engulf potential attackers with swarms of your own fighting platforms.
[Answer]
Mutual sieges abstract to the game go.
Attackers can continually introduce area denial weapons to bottle up defenders, and defenders have to sit in force right on the edge of the danger zone for fear that the next incoming is an invasion fleet instead of a bomb. If even a small attacking force breaks through the huge opportunity to maneuver becomes a big headache for defenders. Any system cut off in this way can be attacked in force eventually with more resources than it can possibly match.
Since attackers finally controlling the system allows attackers to advance, once a system is cut off from the main group it needs to be sieged by its controlling power too. Leading to 30ly buffer-zones under siege from both sides and at least a potential race to envelope larger groups where scale differences would allow eventual decisive action.
[Answer]
The strategy really depends on the specifics of your jump drive, and more importantly your jump points. If they are known and in "fixed" locations, then the obvious strategy is to defend the crap out of them with the equivalent of fixed defenses; minefields, fortresses, whatever is needed.
Can multiple ships come through at once? Then you're looking at beachhead battles, throwing as much as you can through a jump trying to gain a foothold in the system. If, on the other hand, only one ship (or very few) can come through at a time, then large-scale invasions become impractical against industrialized or heavily defended systems. You run into a classic mountain pass defense; it doesn't matter how big your space fleet is if they can only come through one at a time. The defenders have a huge advantage. The Grand Strategy would focus on Cold War style operations: covert actions, political influence. You either want them to voluntarily come on your side or to weaken themselves so much internally that they can't adequately defend the jump points. However, as the invader once you've got control of the jump points, now you own the system. Hell, you might not even bother with an occupation if the system is primarily meant as a waypoint to other systems. Who cares what government they're running on the planet so long as they're smart enough not to provoke you?
The overall strategy is an all-or-nothing. There's no point holding anything back, on attack or defense. You either control the jump point or you don't. There's no point keeping reserve fleet back to defend the planet. This is especially true if the jump points form a network, so there are only certain routes of getting from one system to another. The fleet at Earth isn't doing any good if the enemy has to first take Wolf 359 in order to make it to Sol; better it be out there at Wolf 359 to stop the enemy there.
If, on the other hand, jump points are limited by distance from the center of mass of the system, which is also common, but could otherwise appear anywhere, and it takes time to putter around in-system, then defensive strategy will have mobile fleets close to home. They won't stop someone from entering, because they can't defend a full sphere and distance/velocity limitations means the squadrons out at the jump sphere are going to be useless if the enemy appears on the other side. The best bet in that case is to watch them come in (because you have plenty of time) and move to intercept. In that case, you're looking at more of a World War Two style strategy from the viewpoint of the Axis: you know an amphibious invasion is coming, and given the enemy control of the seas they can pick when and where, so you sit tight and wait for them to come to you.
Of course, that works two ways: the invaders could find themselves trapped or outmaneuvered because they can't stop reinforcements from coming in behind them, or having the defenders send ships back to hit your own system.
The strategy then, would be to ensure you have reserves staying at home while you're out trying to conquer the galaxy.
So, again, it comes down the specifics of how your FTL drive works.
Also, second the recommendation for *The Lost Fleet* series.
] |
[Question]
[
To clarify, in full [Cronenberg](https://en.wikipedia.org/wiki/David_Cronenberg) fashion, I would like to know if there is any biological material that does or can exist that is magnetic and could work in a [Gauss Rifle](https://en.wikipedia.org/wiki/Coilgun).
Using a Gauss Rifle or Coil gun would require ferromagnetic material, but alternatively using a rail gun would not. I would also like to specify that below is meant to be a hand held weapon, however this question is about the **projectile** and not the rifle itself.
What I'm trying to do is to make a rifle that fires bullets that are made of some biological material that is both magnetic enough to fired out of a Gauss Rifle (link describing what that is exactly earlier) and is suitable material to actually make a bullet out of. The early concept was a rifle that "grows" bullets inside it's chamber using a combination of genetic engineering technology and stem cells. The bullet would be hardened on the outside and take the shape of an ordinary modern bullet, perhaps the size of a .22 LR round, but be filled on the inside with some kind of fast acting flesh eating bacteria that would make any wound fatal within a few minutes assuming the bacteria was not killed somehow. However, upon further thought I realized that wearing body armor of any kind would effectively stop these from happening since the bullets would be hollow point in order to shatter inside the target releasing the bacteria. The idea then came to me that accelerating such a bullet to an appropriate speed, and perhaps changing the design slightly, would allow the bio-bullet (as I call them) to pierce the armor. Maybe a bullet designed such that when the wedge applies pressure, or it **meats** (pun) the resistance to spin created by flesh in a person, it widens or breaks? I can't say I know too much about the physics behind projectile weapons so I can only have ideas, not speak to their scientific accuracy.
I've got my heart set on the biological/cronenberg theme, so I'm hoping there is a way to make it work!!
This edit is to explain that while [this](https://worldbuilding.stackexchange.com/questions/64291/could-elephants-evolve-into-living-railguns) question ask if a living animal could evolve to have a railgun as a natural weapon, I am specifically asking about making a projectile outthat can be fired out of a traditional rail gun or coil gun (man made magnets and metal and all that jazz). This is different because it does not have to do with evolution but rather biological engineering, and concerns only the projectile and not the rifle in its entirety.
Additional edit: As can be read in [this paper](http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1296&context=phy_fac) I found, it might seem that genetically altering flesh eating bacteria to take on the additional properties of "Magnetotaxies" (as they are referred to in the paper). These are bacterium that swim along magnetic field lines toward a particular polarity, and additionally **dead bacterium become orientated relative to the magnetic polarity they were observed to follow, even after the poles switched**. Combine these properties with the properties of a flesh eating bacterium, and the first problem of this projectile has been solved.
The remaining problem is the delivery of these bacterium to the target via a hardened, hollow cartridge. The material that comes to mind would be bone, since the magnetic properties of the bacterium would allow for the propulsion of the bullet and thus the cartridge itself does not need to be magnetized. However, the hollow point design is rendered ineffective by body armor and by the fact that these bacteria would be propelled out of the nose of a hollow point bullet by the magnets rather than propelling the bullet itself. a hollow point too small for a bacterium to pass through would render the purpose of the hollow point design, to shatter inside its target, pointless. How might one design a projectile to break upon entering a a human target without using hollow point?
[Answer]
Yes, with a caveat, there are several known usable ferro-magnetic biological materials, most are relatively high in iron. However, they are all microscopic. In most cases the whole reason they exist is for the detection of magnetic fields.
Although there is the option of biological material that serves instead as the raw material that can be refined into what you want, this is already a field of current research: [Biological Routes to Metal Alloy Ferromagnetic Nanostructures](https://pubs.acs.org/doi/abs/10.1021/nl049825n). Biology is good a creating nano-scale structures, so it is under investigation for creating magnetic nanofibers.
[Answer]
I'm not an expert on railguns, but as far as I know, the fired projectile doesn't need to be magnetic itself, it just needs to be "affected" by magnetic fields. Like, for example: simple iron. Not magnetic by itself, but will be attracted to the magnet.
The magnetic field needed to move the projectile is generated by the gun itself.
So any ferrous compound would do as long as it has enough iron in it.
edit: When i write magnetic, i mean having it's own magnetic field, being a magnet itself.
[Answer]
With biological and genetic engineering, the possibilities can be almost endless... Even when working with hard substances, there is the possibility of *infusing* magnetic metal into the material.
The biggest advantage would be that you can work with structures in the bullet that are microscopic in size.
An alternative to bone could be **chitin** or **keratin**, both of which can not only be fabricated to include magnetic materials, but can also be made somewhat porous.
Where the big advantage of your bio-bullet comes in, is that the bullet is not *fabricated* - it is *grown*. In that regard, you can think outside of the box as it were and make use of features that are otherwise impossible in *fabricated* bullets.
This way, you have loads of other possibilities than a hollow-point or syringe-like design.
As the purpose of the bullet would be to administer a type of bacterium, there can be a way to make the bullet shell somewhat porous without sacrificing too much structural integrity.
In order to break through armor, mainly the tip has to be hard and sturdy - the bacterium "pocket" could then be located somewhat to the rear of the bullet.
Thousands to millions of slanted, forward-facing holes could be arranged in a ring around the tip - enabling the force of *deceleration* to act in administering the bacteria, much like in a syringe bullet or dart. In short, you would not need the bullet to *shatter* in this case, but only to *decelerate* enough to remain in the body of the target.
] |
[Question]
[
In a galactic civilization with multiple races, what would be an ideal calendar system that everyone could use? FTL travel is possible (please no answers involving the implications of FTL, for the purposes of this question it is entirely possible without any side effects such as time dilation). Instant communication to anywhere in the galaxy is also possible.
Would there be any way to create a calendar system that everyone could effectively use? A day on this calendar wouldn't have to be the same length as a day on earth, but it should still be close to a human sleep cycle (the other races would presumably have a sleep schedule similar to ours, but if there's any way a calendar could work with radically different schedules that would be great).
[Answer]
I agree with henry taylors answer in that when making new system that can span cultures and languages, you need to break them down into the smallest denominator and then build up. Then it can be more easily translated into different languages(unless you make an intergalactic language and number system aswell).
This is what I really want to say but didn't fit in comments.
You would probably get a galactic time and planetary time. Probably get planetary(jet) lag while getting used to the new days after comming to a new planet. Though I expect occassions to still run on the galactic calender, day to day life would be probably depend on the planet. I would expect planetary time to have days and seasons, so regular things might be;"see you tommorrow"(exactly the same as now) and "see you next summer"(instead of "see you next year"). While galactic time will probably only have measurements like months and years(no days). What happens to days off-planet? Well an electronic assistant can make sure you get enough rest(your on a spaceship, electronics are everywhere), if its a colony ship then lights might automatically dim to make an artificial day-night cycle.
Depending on the culture, it may become that people think of themselves like this; "I was born 18 summers ago or to be more accurate, I am 26 years old"
[Answer]
A calendar is a tool for measuring and subdividing time. Its components (such as Days, Months and Years) are just convenient packages of time. They assist calendar users in equating the passage of time to recognizable spans within their own lifetimes.
So ignoring the packaging, a calendar only needs two components. A starting point and a unit of measure. For the calendar to work across the entire galaxy, both of those components need to be absolute and immutable across all time and space.
I would propose that measuring every moment in time as its distance from the instant of the big bang, in units of atomic seconds where...
>
> the official definition of a second is 9,192,631,770 cycles of the
> radiation that gets an atom of cesium to vibrate between two energy
> states.
>
>
>
*(We might round that cycle count up to an even 10 billion just to make the math easier, but the rest of this answer assumes that we leave it the way it is stated above)*
How we determine the exact instance of the big bang is probably beyond our current science, but hopefully we will figure that part out by the time we colonize the stars.
As for making such a system usable to "people", we would probably create new convenient packages for day to day use. A CentiSecond HectoSecond for 100 seconds could replace the minute. A KiloSec would then be about 16.667 of our minutes, so 4 of them could replace our hours. A MegaSec is only 277.778 of our hours, so that would be close enough to replace our weeks. In fact, it's 11.574 days the equivalent of our fortnight. And with adequate advancements in medicine, average human lifespans might someday reach 10 GigaSecs.
] |
[Question]
[
[Dunbar's number](https://en.wikipedia.org/wiki/Dunbar's_number) is one of the critical elements for humans and societies. Increasing Dunbar's number has been proposed in this question:
[What would be the traits of a humanoid being who would live more comfortably in modern society?](https://worldbuilding.stackexchange.com/questions/55779/what-would-be-the-traits-of-a-humanoid-being-who-would-live-more-comfortably-in)
How would one actually increase that number, so that larger clans/groups could work together with less government?
This seems to be tied in with biology, of course, since humans have been around for a few million years, but we've only had things like agriculture (and large groups of people) for a fraction of that time.
What would we change in our brains? If we had means (technical or otherwise) of direct brain-to-brain connectivity, would our empathy become greater as we understood other points of view more quickly, without making changes to our genetic makeup?
A technical solution might be interesting; instead of going to the library to read a book on social situation X, one might 'plug in' and truly understand the conditions of situation X (from multiple angles). This is somewhat like ST:TNG Inner Light episode. There, technical means were used.
Some sort of psychedelic drug?
[Answer]
>
> Dunbar's number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships—relationships in which an individual knows who each person is and how each person relates to every other person. (Wiki)
>
>
>
This first aspect of Dunbar's Number specifically identifies a "stable social relationship" as one where every person within the group knows everybody else and how they're related. This can't be done with social media which is intrinsically anonymous in nature.
**The important aspect to understand here is that Dunbar's Number has more to do with the quality of the relationship than it does the quantity of relationships. You will meet thousands of people in your lifetime — but how many of them do you actually remember?**
>
> Dunbar explained it informally as "the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar."
>
>
>
This second aspect of Dunbar's Number is incredibly important. It's not just you who's unembarrased meeting someone you know at a bar — they can't be embarrassed, either. That means the relationship is deeper and more complex than can be achieved today through electronic association.
At my largest employer I probably knew by name well over 100 people. I knew about the family life of probably 50 (had met their spouses & children, had met them outside of work). But, at best, only 10 fall into the catagory Dunbar suggests.
**Frankly, the only way to do this is to increase memory, both width and depth.**
*Width:* This is the "multi-tasking" component of memory. It relates the the number of active items you can process at one time. With greater "width" you have the ability to interact with a larger number of people at the moment. This would greatly improve your ability to establish Dunbar-quality relationships.
*Depth:* This is long-term memory. It allows you to reconnect with people you haven't seen for a while. It gives you the ability to retain a greater number of Dunbar relationships. How many people do I remember pre-age-10 that I could claim as Dunbar-quality relationships? Frankly... 3.
To improve my Dunbar Number I would need to remember people, who they are, what their likes & dislikes are, their basic job history, the members of their family... ("John, hi! how's Karen? Is little Larry still interested in being a fireman? Are you still a CPA for Equifax?") — *and they need to remember the same about me.*
**A better human memory means a higher Dunbar Number — whether that translates into needing less government is a highly debatable issue. A higher Dunbar Number won't make people less greedy, less selfish, or less arrogant.**
*BTW, I'm not convinced that telepathic or empathic abilities would automatically improve human relationships. As I mentioned: greed, selfishness, arrogance, lust and a host of other "[less desirable](https://www.youtube.com/watch?v=R8y6DJAeolo)" qualities are part of human nature. Honestly, we'd just find different ways to lie, to cheat, to circumvent rules, etc. In fact, telepathic and empathic abilities might be a curse as people would quickly learn to better hide their feelings and intentions than they do now, making relationships on average even more shallow. That's just my two bits on the matter.*
[Answer]
I think this is already being done; it's called Social Media.
The reality is that maintaining social relationships take a lot more than just intelligence; in the past, these relationships were also limited by the fact that people needed physical proximity in order to relate to each other. The phone expanded our ability to maintain friendships and the like over long distances, but it's tools like Facebook that seems to be truly successful at doing that. I think that's for 2 reasons.
Firstly, photos and videos. That visualisation means people feel like they are truly part of the action. Secondly, social media limits the experience and puts it into an 'interrupt driven' mode; what that means is that you don't get the sense of touch or smell through facebook but we don't seem to really need that to be 'social', or at least one form of it. Also, the other person can post when they have the time, and you read when you have time. Even if these times are disjointed, it doesn't feel like that to the person reading the post.
If we take the limited form of socialisation that sites like Facebook allows as being a new form of social interaction, then for Millennials at least, their Dunbar Number has already risen. For those of us from older generations, we're less likely to lose contact with someone who moves away and therefore our Dunbar Number is also increasing through better retention of existing relationships.
**To address comments...**
Yes, there are some studies that appear to show that the Dunbar Number is unchanged by sites like Facebook, but (in my opinion) they fail to recognise a fundamental fact about the way the human mind has been changing since the invention of the Gutenberg printing press; we are re-wiring ourselves to focus less on memory and more on processing and analytical capability.
This is even more so since the dawn of the internet. Why remember heaps of facts when you can just look them up via Google or Wikipedia? This is especially so in a world where those 'facts' are changing so fast as our understanding of science and other subjects is growing so quickly, rendering old facts obsolete faster than we can learn them.
We no longer ask our children in schools to name the capital cities of a hundred nations. We ask them questions like 'why are many capital cities NOT the economic centre of their nation?'
We're testing their ability to analyse and 'fact-check', not remember.
When we consider this trend, I'd argue that if you take the classical model of the Dunbar Number, Facebook et al are actually *decreasing* our Dunbar numbers because people no longer find it necessary to 'remember' everything about their friends; they have a handy reference available to them at all times. Further, I'd argue that this is the reason most Millennials *prefer* to talk to friends on Facebook rather than organise large social gatherings; they have access to the information they need to interact with each other in the medium in which they choose to interact.
Whether we like it or not, we're using our computers and smart phones as artificial memory. We go to them whenever we need to know something, rather than remember it directly. That frees us up to do the real value added work of analysing the information we retrieve from these devices.
In that sense, (with respect to @JBH's Answer which is very good) we ARE increasing our width and depth of memory *as a species* through artificial means. We're effectively reserving our biological memory as a 'cache' which we fill from our artificial memory, retrieving the relevant information at will, as needed.
In that sense, research that involves surveys to determine Dunbar Numbers misses (in my opinion of course) the one inalienable fact about the way we process information today, including social information; the average person out there CAN'T remember enough to increase their *natural* Dunbar Number, but that's not what counts anymore. In the world of social media, people now have *selective* Dunbar Numbers, meaning that they can selectively remember what they need to about a much larger cohort of individuals on an 'as needed' basis, thanks to what amounts to artificial memory.
[Answer]
One way to achieve that would be to extend healty lifespan to 1000 years.
You definitively meet more people over 10 centuries.
Another way would be to boost our brainpower, if we could process information 100 times faster, communicate more efficiently, remember more things we would be able to interface with more people. As was pointed out, Social Networking is kind of helping us achieving that (not sure about the efficiency part though...)
] |
[Question]
[
I know that birds like crows and parrots can use basic tools, and some questions on the site have stated that re-evolving hands isn't worth the trouble/is outright impossible.
However crows don't build firearms and the questions were asking for simple tools.
My avian race are human sized chickens, their hands are bat-like in structure though the fingers are shorter (they are flightless so i believe there is no need for long fingers to hold the wings correct me if i'm wrong) and hidden by the feathers if those aren't cut, the fingers can be used but it's not very efficient unless the feathers are cut short.
They have access to beak,hand and talon manipulation as is, all the basic furniture and tools of avian manufacture can be used with the talons. **But** **can activities that require great dexterity, that need you to be stable (if you hold something in your foot then there's only one leg holding you) or things like smithing where you don't want to manipulate the materials with your mouth be achieved with talons and beak only ?**
This is a question about the mechanics but I'm mostly asking because I plan for the wings to play a cultural component of my world : for example only the nobility/merchants don't cut their hand feathers because they don't need to work but also to differentiate themselves from the commoners as a sign of wealth. The craftsmen cutting their feathers in order to wear protection gloves being seen as a sacrifice to provide their fellow avians with valuable tools.
First question though so if there is any problem with the formulation, that the question isn't clear or anything please tell me so I can improve it and my future questions.
[Answer]
Hmm ... being smart birds, I think these guys could work around the problems with a combination of teamwork and equipment. Let's look at smithing. The standard image of low-tech smithing is a guy beating iron over an anvil with a hammer, yes? I'd suggest two things:
* Your bird guys (assuming they can fly) must have awe-inspiring chest and back musculature. Perhaps they tie the hammer to their arm and happily beat away; a partner with tongs angles the target iron so all the smith has to do is supply the up-down motion of the hammer.
* These guys are going to invent the drop-hammer tout de suite.
To the more general question, I suggest these guys will rethink a lot of our assumptions as to how fine or strenuous work is done. Weaver birds do *incredible* things with just talon and beak, using their partially built structure to lean against. For delicate work, these bird fellows might work in pairs, taking turns being the holder and the manipulator.
Heck, they might invent a rig where they can hang from their armpits, leaving both feet available to work with. Or lie on their backs.
Admittedly, there is a lot of awkward workaround going on here. Maybe you could work with that ... it's *expensive* to get things made. So people have few possessions. Everything is handcrafted and exquisite, but a middle class family might only own a steamer-trunk full of artifacts. They get by on their own agility and grace, and their passtimes are more oral or acrobatic.
[Answer]
If feathers get in the way of manipulating objects your intelligent tool users will evolve to not have feathers on their hands long before they develop the tools and culture necessary to not cut feathers as a indicator of wealth.
Congratulations you've discovered fingernails.
These days humans can do all sorts of fancy things with our nails if we aren't doing manual labor. We have only reached this point after a long period where every proto-human was needing to work with their hands and manipulate objects constantly for survival. Note for instance that we have less hair on our hands relative to the rest of our bodies.
[Answer]
We are not using feet for precision manipulation and neither our mouth.
There's good reason for that, in site of fact there *are* some persons able to paint with feet or mouth (and I'm not speaking about some "so called" painters seemingly painting with their left foot).
I do remember a very old short novel where a race of alien avians surprised earth researches being able to deftly manipulate tools with their talons.
Talons were thought not possess the necessary dexterity because they are used for locomotion, thus they must be sturdy to lift and balance the whole body.
Trick was to have wings (when not used for flying) capable of being lowered and used as support for the whole body, freeing "legs" from heavy support work to be used "hand-like.
Sorry I don't remember neither author nor exact title.
] |
[Question]
[
The protagonist in my SF story is on an asteroid gazing towards the Sun and inner planets. For purposes of the narrative he needs to locate the position of the earth at *different times* in its orbit.
He is standing on the asteroid, about 2.5 [Astronomical Units](https://en.wikipedia.org/wiki/Astronomical_unit) out, in the asteroid belt, viewing towards the Sun
[](https://i.stack.imgur.com/H02Gd.png)
Since he’s basically outside looking in with regard to the Earth, wouldn’t all the inner planets line up in a straight line passing through the sun?
Wouldn’t the Earth (and Mercury, Venus, and Mars) move back and forth along that imaginary line (red arrows), their location along that line depending on what point they are in the orbit? For instance, Venus could appear to be inside Mercury, as in my drawing, correct?
Edit: the asteroid has little or no inclination.
[Answer]
Yes, that's approximately how it would look, with some caveats:
* The asteroid is orbiting the sun, too, so your protagonist isn't a completely stationary observer (although it will orbit slower, since it is further out).
* The sun is bright, so you may need to have something to block it to observe carefully.
* Any planets closer to the sun than you will have phases, [like we observe on Venus](https://en.wikipedia.org/wiki/Phases_of_Venus). The observer would be able to determine, then, whether the planet is in *front* or the *back* part of their orbit around the sun.
* All the planets are *very slightly* tipped, so they likely won't actually *transit* (pass directly across) the sun on every orbit. Compare the frequency of [transits of Venus](https://en.wikipedia.org/wiki/Transit_of_Venus) and [transits of Mercury](https://en.wikipedia.org/wiki/Transit_of_Mercury).
* Unless other asteriods come close, Earth's moon is probably the only other object large enough to distinguish, at least toward the sun.
[Answer]
No, this wouldn't occur, due to something called [orbital inclination](https://en.wikipedia.org/wiki/Orbital_inclination). None of the planets orbit in exactly the same plane. Their orbits are a little tilted relative to each other. Some are easier to notice than others, but Mercury has a pretty big tilt (6 degrees) that would definitely be noticeable. This handy figure shows the inclination for all the planets:
[](https://i.stack.imgur.com/oFhsz.png)
What is more, as you can see from the 3D map below, not only are their inclinations different, they are bent in different directions, throwing the line even more off (which is why the angles on the Wikipedia page above don't seem to line up):
[](https://i.stack.imgur.com/IbCEW.jpg)
As you can see from the 3D map, if you include Pluto then the whole thing is way off, it has a huge orbital inclination of 17 degrees (depending on how you measure it)
[Answer]
What you described would more or less occur, provided the light from the sun can be blocked out, the planets would appear to line up. Over the course of the year(s) they would appear to move back and fourth. However, the planets would be much less visible, if at all, at their closest approaches to the observer because the sunlight would not be reflecting off of them.
[Answer]
Not quite.
Inferior planets (ones closer to the sun than your orbit) will appear to move a set number of degrees on either side of the sun. You show Earth as moving on a short path. That path will take across the sun to the other side.
From an asteroid at 2.5 AU, the earth would move from about 22 degrees on one side of the sun to 22 degrees on the other side. Venus and Mercury will be proportionally less.
You can figure out what side of the orbit they are on by brightness. While further away when the planet is on the far side, most of the disk you see is facing the sun, on the nearside most of the face you see is dark.
] |
[Question]
[
In an [Electric Universe](http://www.electricuniverse.info/Introduction), where space is plasma soup and electromagnetism is the "magic" that can defeat the laws of physics, all stars are connected by invisible Birkland currents. Picture the rope that forms when you touch a plasma ball:
[](https://i.stack.imgur.com/Nvg8B.png)
These natural electric currents are exploited for FTL travel. In simple terms, starships travel inside a magnetic bubble along an electric current to a nearby star, drop the bubble just in time to turn via gravity/slingshot, and then follow another electric rope to the next star.
A few star systems (early Type II on the Kardashev scale) have created super-highways by strengthening the weak Birkland current between two distant stars. They can now skip past the connecting stars and travel directly hub to hub. Assuming navigational stars are average 5 light years apart, let's estimate a super-highway at 20 to 25 light years.
My question is about the devices they use to do this.
## the device, I think...?
I am picturing something like AC transformers, a mega-structure in space that converts the stars' electricity to a higher voltage, with a synchronized transformer at the other end. I'm not an electrical engineer so please correct me if I'm using the wrong electrical analogy.
This is my placeholder artwork from an earlier draft:
[](https://i.stack.imgur.com/wUNW3.png)
According to Electric Universe pseudo-science, all stars should have an ion jet at their magnetic poles. I want to pin the device above one of the poles (both if the star has two connections) using magnetic flux against the star.
The device's own magnetic field is so strong that it defeats gravity around it (wacky space). Parts of the device are discontiguous, but it all probably rotates as one large object. It is powered by the star's ion stream, and converts part of that stream to the "high voltage" Birkland current.
## why does it matter, in context to the story
In the story, a robot protagonist has to journey into the device to repair an AI. It serves as a hero's journey to heaven/hell mythos. My goal is not hard science, but I'd like the electricity analogy to make sense, and inform how I structure the device.
## the question, specifically
What is the general structure of the device? What are the physical and electrical parts? How big is it? Does it spin crazy fast?
Is the AC transformer analogy a good model? Would it impact the stars at all to wire them up in sequence?
**Disclaimer**: *I am not trying to honor any beliefs specific to Electric Universe Theory, so perhaps Teslapunk would be a better genre description. I'm also fine with calling it "magic that is analogous to electricity".*
[Answer]
# You want a pair of step up/step down transformers
First off, I am assuming you want not-real world science, but real world engineering, to make the protagonist's story and repair duties reasonable. In that case I am going to handwave the science and describe equipment that would work by analogy.
Using the pseudo-science electricity analogy, you want to use transformers for long range power transmission. Here on Earth, $P = VI$; power ($P$) equals potential or voltage ($V$) times current ($I$). High current leads directly to power losses due to resistance. So the best way to transmit over long distances is to lower the current as much as possible. Given the power equation, this can be done by raising voltage. Therefore, you want your stations, instead of increasing the current of plasma between stars, to in crease the 'potential' between the stars.
Note that this is more like DC than AC, because you don't want your interstellar plasma reversing directions (or else your travellers will never get anywhere).
# Transformers (more than meets the eye?)
The simplest way to make a large (very large) transformer is to do it with a shell type transformer ([Source](http://4mechtech.blogspot.com/2015/08/construction-and-working-principle-transformer.html)).
There are basically three components: a low voltage winding that picks up the plamsa-magnetic energy from the star, the high voltage winding that broadcasts that energy into space, and the conductive core that transfers between the two. The core would not at all have to be as simple as shown. Here is a real life transformer:
[](https://i.stack.imgur.com/6B9tH.jpg)
It is not a great picture, since the vanes you see in the foreground are what brings high voltage electricity out of the transformer, but it helps give a picture of the overall complexity.
Still the overall picture is that there will be a lower coil connected to the Birkland stream coming from the star. This 'ion jet' will have high current but lower potential, but since the particle density will be higher it will be more obviously visible. Then there will be an upper coil of facing in the direction of the next star. The plasma emitted from this will much less dense, but have much higher energy. It might be barely visible to the naked eye, but shine like a torch in the X-ray spectrum. I imagine these two coild are placed one inside the other in the center of the structure, with the high-voltage coil (which needs more loops) inside the low-voltage. Plasma would be pulled from the sun's surface to surround the outer coil, while a narrow high energy beam is emitted from the inner coil.
The core will be a complex structure of a pure metal (iron works great, if you have that in your universe). It would have many loops of differing configurations, each designed so that the 'eddy current' and various losses inside cancel with other components and does not affect the transmission of plasma.
# We need support components
We have to combine this with JDLugosz' superconducting ring (very large, around the outside of the whole structure) to keep the station in place. We may need the various parts of the core to be able to move so as to optimize transmission based on whatever magnetic conditions are going on at the surface. Since this station is surrounded by plasma but still needs parts to move based on star conditions, an AI is ideal for this job.
Since this is a piece of critical infrastructure, you would design the AI with backups. For example, the core might have four parallel structures (loops), one built on each of the four directions from the coils in the center. Since these cores have moving parts needed to optimize potential in the inner core, each core would be separately controlled by two AI's. If one AI failed, then the other would take its place. Which AI was in charge would alternate each day. For interstellar transit, three of the four loops would be needed to keep the structure working. If a loop was lost, all objects in transit would be in development and then the structure would shut down for repairs. If one of the two AIs went down, then a robot protagonist would likely be sent to conduct repairs.
# Size and stuff
The energy needed to travel at the speed of light or beyond is significant. Lets assume that it takes $mc^2$ energy to accelerate something to interstellar speed with these structures, because that is as good of a guess as any. In that case, sending a 100,000 ton freighter takes about $9\times10^{24} \text{ J}$, which is actually kind of a lot. That is around 1% of the sun's output each second. But lets say that we take a whole day to accelerate each freighter to that speed; now the power requirement is $1\times10^{20} \text{ W}$. This is better, and about 1/5 of the world energy consumption.
In terms of the sun, that is 0.000026 % of the sun's total output, so a reasonable guess for the station is that it must cover that much of the sun's total surface area, which is 1.6 million square kilometers, or the size of Iran or Alaska. Therefore, I conclude that the plasma jet from the sun going up to this structure will have about that surface area. If the jet envelopes the outside of the outer coil, but does not cover the superconducting ring that keeps the station locked in place, then the superconducting ring might have radius of about 800km; the outer coil 500 km, and the inner coil maybe 100 km.
As for parts, I can't imagine servos being practical for pieces of a station that big. I would imagine there are no mechanical parts and all the core components have their position adjusted magnetically. There would not need to be any spinning, crazy or otherwise.
As far as wiring up the stars, if you were doing this with AC there would be no actual transmission of plasma from one star to the other. The current in AC goes back and forth as a sine wave; the electrons ever actually reach either end of the cord. So your plasma wave would just be moving back in forth in space, presumably providing power to someone riding along it (I imagine they would use the plasma stream like the third rail of a train, rather than ride inside of it)
# Conclusion
Cool concept, I hope I provided some ideas on how to implement it. This post was pretty stream-of-conscious-ish so let me know if anything does not make sense.
[Answer]
In the normal universe, a superconductor can be pinned to a particular pattern of flux. If nothing in your EU messes that up, you should be able to park a superconductive ring anywhere near the star where the flux doesn’t change. So while most of the surface is covered with bands and loops that boil and wiggle, suppose that your polar vortex is *stable* and provides a unique place for this to work.
It needs to be a **ring** to support the currents that cancel any movement. The bigger it is, the more grip it has, *and* it needs to be of a scale so it sees different flux lines rather than freely sliding along one. It does not spin or anything.
Look into two effects of interest: [flux pinning](https://en.wikipedia.org/wiki/Flux_pinning) and [Meissner effect](https://en.wikipedia.org/wiki/Meissner_effect).
] |
[Question]
[
Thanks for taking a moment to help me understand the feasibility of this scenario. Essentially, what I am looking at is an Earth-like world that would be between 1.3x and 1.6x the mass of our own planet, but unlike our own planet this world has multiple natural satellites, each of which are the size of, or smaller than our moon and also capable of supporting life.
**Stars**
This star system is intended to be a binary system comprised of two red dwarf stars. The idea here being that this would allow the system to last for an incredibly long time as to my understanding, red dwarves are some of the longest lasting types of stars in the known universe. I also like the idea of seeing two stars in the sky of some of these worlds during the day.
**Earth-Like Planet**
Almost identical to our own world with polar ice caps, large oceans, but more continents of various sizes and shapes. The idea is that there will be many different population centers, isolated from one another, allowing for different levels and types of technologies to be developed almost as if each of these continents are their own little world.
**Moon 1**
The largest of the satellites, this moon is mostly covered in tundra and glaciers, a very cold climate dominated by a species specially adapted to the harsh conditions. This world is intended to have normal "day-night" cycles like we have on Earth, or at least relatively normal, but with days becoming incredibly short or non-existent on parts of the world during what would be described as the "winter months". This world would have mostly frozen lakes and little to no "oceans".
**Moon 2**
The second largest of the natural satellites, this world is meant to be humid, mostly covered in jungle and swamp, but with a few pockets of temperate forest sprinkled here and there, probably near the poles. Though this world would be on average warmer than our Earth, I don't think the heat and humidity would get to levels that would be uninhabitable for life, or at least that is the intent. This world may have one moderate sized ocean, but plenty of lakes and marshes.
**Moon 3**
A smallish sized moon, this world would be mostly comprised of a desert enveloping the majority of its surface, with large oases and several rivers with more fertile soil near the banks/flood plains available to allow for sustaining decent sized population centers. Some portions of the world would be more like barren "scrublands" or a steppe-like envrionment. Similar to the second moon, the idea is that this world doesn't become uninhabital in areas due to the heat (but perhaps due to limited sources of water in some locations), nor would it become too cold at night to kill off the entire population.
**In Summary**
Giving the information provided (as limited as it may be), would it be possible for a world such as this to exist in a way that populations could not only live, but thrive, on each of the mentioned moons as well as the world they orbit? Would the gravitational pull of these moons be obstructed or manipulated by the binary stars their host orbits, considering the planet would be far closer to them than our own Earth is to its sun because of the nature of red dwarf stars? Could a stable orbit exist for all of these entities and still allow for relatively normal day/night cycles, even when taking the multiple stars into account?
If any more information is required, and I can supply it, I would love to do so. Honestly, astrophysics is not one of my strong points :) Thanks for taking the time to read my vague but long-winded descriptions!
[Answer]
So there are basically three problems to deal with here:
# Atmosphere.
Your three moons need to maintain separate atmospheres, and this requires them to be *large* as well as probably *magnetic*. Planets are constantly losing atmosphere mass due to the sun heating up their surfaces which heats up the gases in the atmosphere: as random thermal kicks give atoms too much kinetic energy, they fly off to infinity free from the gravitational well. You can basically model this as a ratio of temperatures: there is a well-defined temperature where the random thermal kicks are *always* enough to kick off molecules of a certain molecular mass $m$, versus the temperature of the surface. The first number is given by $k\_\text B T = G M m / R,$ for Earth and N2 gas it's something like 210 000 kelvin as opposed to the actual surface temperature of ~300 kelvin, giving a factor of 700 between them. Getting closer to the hydrogen that we don't have too much of in our atmosphere you see that this factor reduces to 50 or so.
Note that neither Venus nor Mars have magnetic fields, so it's helpful to analyze them by this criterion. In both cases their atmospheres are mostly CO2. We see that Venus keeps a super-thick carbon dioxide atmosphere with a temperature ratio of ~400, while Mars has almost no atmosphere with a temperature ratio of ~90. So if the minimum temperature ratio to keep a meaningful atmosphere were something like, say, 100-200, then you can't make these much smaller than 1/3 to 1/7th of Earth's mass. You can maybe make the central planet bigger but you can't make the moons much smaller than this.
# Temperature and day length
If you're going to have had these planets in mutual orbit for a long time, then probably most of these moons will be *tidally locked*. Tidal locking describes something that our Moon has done with us, where it always points one face towards us, rotating exactly once about its axis per revolution about the planet. As the name states, it does this because the tidal force of the Earth deforms the Moon slightly, just like its tidal force does to our water, causing our tides. This always causes friction, and in the Moon that friction has met its ultimate conclusion: the Moon is now as "stationary" as its conserved angular momentum will allow it to be. That's what tidal locking is about.
Well, basically, the day on the Moon lasts the 28 days of a lunar cycle as seen from Earth. So the cycles you're going to see are actually going to consist of a sort of monthly summer-winter-summer-winter cycle or so, especially if you do not have something like a big ocean to absorb a lot of that variability. So you want to work on explanations for why the temperature *doesn't* fluctuate rapidly on each of these moons, because the expectation is that it would.
# Chaos and where the moons came from.
The Moon is surprisingly large relative to us, more than 1% of our mass. That's incredibly uncommon among the moons we know and is usually explained by a huge catastrophic collision turning us into a big soupy ball of magma while it ejected a huge chunk of Earth's mass into orbit around it.
Fortunately the Sun and other planets are very far away and we can kind of ignore their effects upon the Earth-Moon system. It's very likely that other moons, we could not thus ignore. Remember that they have to have relatively large masses compared to the Earth, and this creates a nasty situation in the equations that is called the "three-body problem": we do not have analytical solutions for more than 2 bodies orbiting each other in celestial mechanics. In fact under many situations of comparable masses, those 3-body problems become nasty chaotic things: and life tends to need predictable circumstances otherwise evolution cannot easily adapt that life to those changes.
So you want to space the moons out as much as you can, and you are limited in this because the furthest moon needs to still be well within the [Hill sphere](https://en.wikipedia.org/wiki/Hill_sphere) to be comfortably considered a satellite.
Even then, you risk a lot because those inner planets can often see some serious tidal forces from the combination of the other moons and the central planet. For example [Io](https://en.wikipedia.org/wiki/Io_(moon)) is the most volcanic object in the solar system because of this sort of situation; it can't come to a nice tidally locked equilibrium because of these other planets.
# Binary systems and larger
Part of the problem is that you are describing "moons" rather than "planets", and moons are by definition small. There is no reason that within the Earth-Moon system you can't make the Moon significantly larger, until it is about the size of the Earth and they both orbit a central point. Then they might be tidally locked but they might also be co-orbiting this central point once per day, in what's called a "double planet" system. In fact we have observed [triple stars with planets](https://www.theverge.com/2016/7/7/12111660/exoplanet-three-suns-very-large-telescope-direct-imaging) and so we know that triple-planetary systems are possible, and that they could even potentially have a moon.
(Side note: please use caution when googling for examples of triple planets as you will get deceptive answers. We have only recently been able to detect planets orbiting distant stars -- so "triple planet" right now generally means "the wobble in the signal appears to be unfittable with 2 sine waves, so there must be at least three planets around that star". Actually seeing light illuminating one of these rocks and discovering that it's actually three rocks orbiting a common center, is not possible right now, to my knowledge: even if you saw the "bulge" in the star from its reflected light I don't think you would see the "gap" between the planets.)
# Multiple orbits
You can also have multiple planets orbiting a central star within the Habitable zone on different orbits, if they're many Hill radii apart from each other so that they do not mess with each other too much. [This blog post](https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/) has 6 concentric orbits in the Sun's habitable zone but also comes up with a hypothetical alien-engineered system which could have as many as 416 in orbit around a Sun-sized star. It's artificial -- it wouldn't form in nature -- but it points out that this is a really tangible possibility.
[Answer]
Short answer. It may be possible for a broadly defined Earth-like planet to have one or more moons large enough to have external biospheres their surfaces.
But it seems difficult for even huge gas giant planets like Jupiter to have moons large enough to have substantial atmospheres and thus external surface biospheres (like Earth has, instead of being under ice or rock).
It is theoretically possible for a giant planet to orbit in the habitable zone of a star (a "hot Jupiter") and have one or more giant moons large enough to have Earth-like biospheres. There are no known examples of any giant planets having moons that large.
And it is theoretically possible for an Earth-like world with an Earth-like biosphere to have one moon also large enough to have an Earth-like biosphere. That should be much rarer than giant planets having such large moons. It would be an example of an Earth-like planet have a moon system with a much greater total mass than the moon systems of giant planets like Jupiter or Saturn.
But the planet-moon relationship would not be so obvious in that case. The sizes of the two bodies would be similar enough that people would tend to think of it as a double planet, just as Earth and the Moon and Pluto and Charon have been described as double planets.
If you add a third body large enough to have an Earth-like biosphere it gets even weirder. once again you have a tiny Earth-like planet having a moon system with a total mass of several times the total mass of the moon system of a giant planet like Jupiter or Saturn. Of course one might suppose that the Earth-like planet is so small because it split off so much of its mass forming giant moons.
I wrote an answer to a similar question recently about an Earth-like plane with an Earth-like moon or (smaller sister planet).
[How would an earth-like planet with a habitable moon work and how to get there?](https://worldbuilding.stackexchange.com/questions/15642/how-would-an-earth-like-planet-with-a-habitable-moon-work-and-how-to-get-there/76314#76314[1])
In it I give suggestions for how to not seem silly while writing about an Earth-like planet with a single moon large enough to have an Earth-like biosphere.
Note that I quote a source that suggests that a habitable Earth-like world -whether a planet or a moon of a planet, should have a mass beteen 0.25 and 2.0 that of Earth. Thus the planet could have at most about four to eight times the mass of one of it's habitable moons - making them seem like a double planet, and if it has several habitable moons it may not have more mass than the total mass of the moons.
Thus you might want to think of your set up as a multiple planet system, roughly analogous to a multiple star system. Multiple star systems usually have hierarchical orbital arrangements. The two innermost stars orbit each other at a close distance, and another star or pair of stars orbits them at several times their distance, and a third star or pair of stars orbits them at several times the distance of the second star or pair.
For example, the star system of Castor has three double star pairs that are each very close. The star pair Castor A and the Star Pair castor B are separated by many times the separation of the stars within the pairs, and the pair Castor C orbits at perhaps ten times the distance between A and B.
So maybe your planet and moons should be thought of as a quadruple planet, consisting of two double planets separated by a distance at leat several times the orbital distance of each pair.
For example, each pair cold be separated by 50,000 miles and the to pairs could be separated by 500,000 miles.
Another version would be to have the "planet" and the "inner moon" orbit each other about 50,000 miles apart, have the "second moon" orbit the pair at a distance of about 100,000 miles, and the "third moon" orbit the pair at a distance of about 200,000 miles.
But I suspect that an expert on orbital dynamics could find flaws with those suggestions too, demonstrating why they were impossible just as much as your original suggestion.
It might be much more plausible to have a hot Jupiter type planet with four habitable moons, one the "planet" in your question and the other three the "moons in your question.
[How would an earth-like planet with a habitable moon work and how to get there?](https://worldbuilding.stackexchange.com/questions/15642/how-would-an-earth-like-planet-with-a-habitable-moon-work-and-how-to-get-there/76314#76314)
[Answer]
Life on your planet is Feasible, you would need to consider the implication of three moons on the tide. our moon pulls the water towards it; if you have two moons the tides would be very weak when they are at the opposite ends and very strong when they are at the same. imagine the three separate moons at the same time. You would have times when the tides would be extremely strong and others when it would be close to mute and everything in between. This would affect life as do our tides. life on the planet works but the moons are tricky, our moon doesn't weight enough to keep gasses close to it, therefore no atmosphere. which means you can't really have life on your moon. Creating life is still a huge mystery you need heat and chemical soup one theory I read said Mabey even lighting played a part.all of which you need atmosphere for and moons are to light so it won't work. unless you can find a crazy way to explain it, Mabey flora and fauna came to the moons form your planet moving there space somehow? it is tricky. I know this isn't what you wanted to hear, Sorry.
Have fun Building!
[Answer]
The first thing to remember is that in your own universe you can do anything you wish. However, when it comes to realism, your scenario is highly, highly unlikely.
First of all, consider that in order to retain their atmospheres, each satellite will require a fairly strong magnetic field (at least compared to our own Moon). Those atmospheres will also keep the surface of each moon from being microwaved by the Sun. This implies a fairly strong atmosphere, and thus a molten core, like Earth's. However, that doesn't work too well for "small" moons orbiting a moderately sized planet. You need a larger planet than that to "fit" a molten core into.
Second, you're talking about each of these moons having quite different biomes. One frozen, one very hot and dry, another very hot and wet, etc. However, these moons will all be spinning around this world of yours, and be exposed to the same (or at least a very similar) amount of heat from the Sun.
And so, I don't think that a world the size you're describing would be able to support ***three*** moons large enough that each would have a molten core, and a gravity field strong enough to generate an atmosphere which would be able to retain enough gasses for Earth-like climate, and fauna to evolve.
Furthermore, even if these moons did form in such a way as to retain atmospheres, and life did bloom on each one, I don't see how they might each have such different temperature ranges (dry vs humid might be explained by the amount of water available, but not the temperature).
] |
[Question]
[
I'm creating a world opposite of [Les Visiteurs](https://en.wikipedia.org/wiki/Les_Visiteurs), where modern age structural engineer accidentally time travels to 13th century. When guards of the local lord arrest him on suspicion of being a spy, due to his weird clothing and the way he talks, he claims that he's mason from abroad looking for work. The lord is just starting a new castle and needs skilled workers, so he hires him but feels deeply suspicious of him, so he tells the [Master Mason](http://www.historylearningsite.co.uk/medieval-england/medieval-masons/) to keep an eye on the newcomer.
Would the Master Mason have any use of modern structural engineer knowledge or their level of technology is too low for any of it to be practical?
[Answer]
Your structural engineer will have to have a very scientific mind - undoubtedly he has many skills which will be extremely useful, but he has to be able to convince his new colleagues of his theories.
Material strength, beam theory and formulae for the elasticity of materials had not yet been invented; these would allow for much more accurate calculations during construction. This would equate to great savings in terms of material cost; instead of throwing up all the superstructure possible to ensure a building is strong enough, they can now calculate the required strength and use only what is necessary, with a little factor of safety included.
Calculus had not yet been invented. This is one of an engineer's most important mathematical tools today, used to determine the forces in complex configurations of structural elements, shear strength of soil foundations, and lateral earth pressure and slope stability - all very useful for a castle which may be built atop a mound. Calculus is also useful for friction calculations.
Modern materials such as concrete could have been invented much sooner, as long as your engineer knows the correct properties and composition required.
But all of this relies on his ability to prove these mad ideas to his superior - whether through models and examples, or mathematical proofs.
[Answer]
My former flatmate was structural engineer so take this answer as a second hand guesswork from my conversations with him. Because I don't know anyone else in that profession I assume he was typical example.
Structural engineering was his Master while his undergraduate was Civil Engineering. So your hero knows a lot about building things. He also knows a lot about building materials, and though most of the modern materials are not available to him, he knows very well the classical ones too like brick, stone, timber, mortar and their properties.
Your hero also knows how to use iron, I expect this to be quite expensive in the 13th century but maybe its use on few strategic places won't break the budget. He also knows about roman concrete if volcanic sand is available. Though Portland cement with reinforced steel bars is not available, I assume he could think of poor man substitute with Iron and whatever materials he has at hand.
His Math is very strong, and being able to design and calculate the strength of each part of the building, would be of much use to Master Mason who probably works only through experience. it would be tedious without calculator but it could be done.
Also he certainly knows about many famous buildings through the history including medieval ones, I expect that 7 century advantage vastly exceeds whatever special knowledge Master Mason has.
In short I expect him to be very, very useful, working together they could build a hell of a castle.
] |
[Question]
[
>
> *Why certainly! We have all sorts of exotic drink. Can I excite you for a pint of Tarnesian Starköl - bitter, tart, nutty brew this stuff; or rather have shot of H'elvanian Whisky(?) - 7 years old(!), strong, but with a sweet finish... Actually, looking at you more closely - you're not from the area, are you? What about a glass of Hatjörn's Gift then? On the house.*
>
>
>
Hans Jånsson - Bartender & Proprietor of the *Prowling Goblet*
---
Welcome to the *Most Ingenious Questions You Never Thought of*. Today we look at the booze-rat, one-last-time. An animal aptly named for its unique defensive mechanism of [storing potent alcohol in its body](https://worldbuilding.stackexchange.com/questions/56710) in order to [daze/incapacitate a predator](https://worldbuilding.stackexchange.com/questions/56945).
Well no, we're actually looking at the question that has been around as long as the booze-rat: How do we drink it?
The booze-rat has evolved [additional organs](https://worldbuilding.stackexchange.com/a/56951/2746) in order to a) produce the alcohol it needs for its defense, and b) keep itself safe from the negative effects of alcohol poisoning.
---
**Q**: How do the people of Hjårdan *cultivate* their unusual source of alcohol?
[Answer]
# Use a Strigil
[link](https://en.wikipedia.org/wiki/Strigil)
[](https://i.stack.imgur.com/QRZTo.jpg)
The farmers can use this to scrape the alcoholic gunk off the rats and pour it into jugs/bowls. Obviously, the form of the implement can be adjusted somewhat to cater for the rats physical form.
Holding the rat down and not getting yourself bitten might be a bit of a challenge, but that's why booze-rat booze is so expensive, right?
[Answer]
They applied Pavlov's experiment on Booze rats and got them to trigger the booze delivery mechanism with simpler stimuli than extreme stress -
**Initially**, booze rats were farmed like chickens in **Battery Cages**. The battery cages restricted movement and kept the rats permanently positioned to deliver the booze to the appropriately positioned booze receptacles colored red. Electric current was applied every hour that forced them to shoot the booze straight into the receptacles.
Later, electric current was accompanied by a distinct ultrasonic whistle and followed by food until the booze rats started shooting the booze upon hearing just the sound. The booze rats that still required electric current after a few generations were not bred.
Finally, the Battery Cages were replaced with better housing at the request of Booze Rat rights/cruelty groups but Booze Rats never forgot to shoot the booze into the red receptacle when they heard the whistle. Now, free range organic Booze Rat booze is also available.
Note: Some farms have also done away with whistles. They have bred booze rats to shoot the booze into receptacles every 3 hours (in return for food) instead. Same principles, different techniques.
[Answer]
## Bred to be Boozy
When humans first began to [domesticate dogs](https://en.wikipedia.org/wiki/Origin_of_the_domestic_dog#Commensal_pathway), we bred the ones with the traits we desired - fastest, most obedient - and disposed of the ones we didn't like.
When humans first began to [domesticate sheep](http://archaeology.about.com/od/shthroughsiterms/qt/Sheep-History.htm), we did the same thing - we bred them until the females didn't have horns, and until they were smaller, to require less food and take up less space.
*When a culture farms an animal, they will breed it to be easier to farm.*
**Let's apply this to booze rats.**
First and foremost, domestication makes animals (mostly) **docile.** Farmed booze rats will not attack farmers, similarly to how domestic cats and dogs tend not to attack their owners.
Next, this allows us to get boozier rats! Just as you can breed the sheep with better and more wool, you can breed the rats with larger alcohol-storing organs or better tasting alcohol with each other, and, over time, you will end up with a better stock.
Finally, consider growth hormones. Not necessarily necessary, but we already use them in much of our livestock today - is it a stretch to make bigger booze rats in this way?
## Collecting the Booze
Now that we have docile, fat rats with large sacs full of booze, let's collect it.
**Skin Vesicles**
If you're going by [this](https://worldbuilding.stackexchange.com/questions/56710/how-does-the-booze-rat-fuel-its-defensive-mechanism/56951#56951) question's answer, the *skin* of the rat has multiple pouches filled with booze. After selective breeding, the pouches can be larger, but regardless, you must puncture the animal to collect its alcohol. I see two methods of doing this:
* Freerange passive collection: There are needles poking into these pouches, attached to tubes, which connect to a flat storage container on the rat's stomach or back. The tank can be unscrewed and replaced daily, then the alcohol can be processed.
* Caged passive collection: There are needles poking into the pouches, but the rat is caged and unable to move; slightly less humane but more space-conservative alternative.
* Active collection: The rats are allowed to roam, but alcohol is taken from their sacs in large syringes - each of which can hold the contents of multiple rats' bodies - every few hours. Alternatively, if that's too industrial for you, consider puncturing the glands with metal needles and draining them into buckets - more "farmlike" if that appeals to you.
**Spray Glands**
If you're going by [this](https://worldbuilding.stackexchange.com/questions/56945/how-did-the-booze-rat-evolve-its-defensive-mechanism) question's answer, there is a single sac located somewhere on the body, from which the creature sprays. There are several ways to harvest the booze if this is the case:
* Caged collection: The rats cannot move, and tubes extend both into the glands and wrap around the exterior orifice; all liquid created or released through optional stimuli will be harvested.
* Freerange collection: Farm the rats on a smooth, slanted surface with grating or netting at one end. Feed them from tubes, like guinea pigs, and introduce a worker every few hours to simulate a predator - causing them to spray, and draining the booze into a trough. May need to be filtered from excrement.
## Why these methods are better than other suggestions (the competitive side of me shining through)
* You don't need to teach any rats what stimuli should make them produce booze - which, on an industrial or larger scale, is costly
* It's more scalable than drinking from the actual rat
* Does not necessarily require agitating the rats, depending on the method, and they may also be allowed to roam freerange
* Few methods I listed introduce extra gunk (from scraping)
[Answer]
The live Booze-Rat is brought to a table, sedated and then bound. When it awakes, the customer frightens the rat by raising it to his open mouth, thus ingesting the strong alcoholic slurry when it is released.
A domesticated breed of Booze-Rat may no longer be scared by this process, but would instead have to be specially trained and rewarded for their actions: once getting “milked" they return to their enclosure to be fed something tasty.
[Answer]
If the booze-rat uses the alcohol as a defense mechanism, it must have a delivery system. Does it spray, like a skunk? Or bite and inject, like a snake? Either way, milking would involve holding the rat in some way, agitating it to trigger its defenses, and collect the juice.
I can't help thinking about plopping them into something like this:
Just attach the hose to the end where the booze comes out.
] |
[Question]
[
I have an idea about a person, who knows exact date and time of significant future events. But does not know what is going to happen. And the dates such person knows are significant for culture that person is inside:
Example: That person knows exact date and time when new president of USA is going to be elected/announced (meaning the exact date and time after counting of the votes when the rival is going to step up and say: "I lost").
But true name of president of USA is unknown for that person.
Also, if there is civil war going on in Zambia and no one inside USA cares, as long as that person is inside USA, he does not know even the date of next bloody event. But once that person travels to Zambia, he instantly knows the date (but still not the event)
That person knows all the significant dates up to one year to the future. Of course, some events are guessable (as of presidential elections), but sometimes you have to wait and see what happens on 4th November 2016, 21:30
The dates are "significant" in a way where more than 60% of population of such culture would speak about the event. Which means, you have predictions both about terrorist attacks and say some hollywood class star announcing publically their sexuality.
**Is there something positive you can do with such ability?**
Especially if such significant dates for the USA can also be terrorist attacks in Paris (I assume more than 60% of Americans did care about the event), so you can trigger homeland security over "nothing"
[Answer]
An interesting question: and one for which I think the answer is yes, but only with some serious high level support.
Firstly: Notices from this person can be used to inform security services about impending threats. If they cross-reference their information with his prediction of dates, then it becomes quite the tool for knowing when additional security may be required.
Secondly: Your post indicates that there's a geographical component to this power. I'm going to assume that it's not exactly split along country lines (as what a Texan cares about may not be what a New Yorker cares about), but that it instead works on proximity. At this point you can use the guy (for some events, at least) as a proximity sensor. Again: Cross reference this information and you help out a lot of security services, but you'll need to move him around a *lot*.
Thirdly: The cultural component, depending on how you break it down, can be of incredible use. If this man is isolated with a group of 9 year olds, and that affects his power, then sitting him in a room with 400 intelligence analysis and letting him soak up the cultural quirks of the spooks is going to skew which events he picks up on. They might not care about the results of the next baseball game, but they do care about the assassination attempt at a national conference the day after. If the geographical component is the main deal here, however, then this takes a back seat somewhat.
For example. The man throws out a date that the US security services say 'ah, we think a terrorist organisation from Madeupistan is planning something around those dates' They put this man on a plane, fly him over Madeupistan and see if the date is the same there as it is in the US. If it is, then they can be pretty certain that the event in question is one that Madeupistan will care about, and they should increase security. If not then they can assume that it will be a piece of celebrity dross that no-one outside the US will care about.
This effect can even be exploited with friendly countries, as the next major event the UK will care about might not be the same as the US if it's anything that's not an international incident. Of course: false positives such as 'Celebrity X announces shock pregnancy!' might bridge the gap, but you can narrow down your parameters quite successfully using this technique.
Of course: Your guy is going to be constantly jet lagged and essentially a prisoner of various TLO's, but he'll be helping!
[Answer]
To stay in the spirit of the question, what can be done without trying to determine the nature of the event?
* Just before the next event, buy financial instruments which "bet on instability" like gold or certain weird derivatives. You can make money on a stock which goes down, if you guessed right ...
* After some years, the character will have made enough money to make significant donations for his or her favorite cause.
] |
[Question]
[
This concept is relatively simple. There are many animals which start mobile, but become [sessile](https://en.wikipedia.org/wiki/Sessility_(zoology)) later in their life history, all of which are simple and primitive. And I was wondering this: what is the upper limit on animal size? And I realized that in the ocean, that limit is probably simply determined on not being so massive that it kills you. But on land, you would die from being unable to move, find food and water etc., long before you die from suffocating under your own weight. So I realized you could have a mammal (or other complex animal, even an insect would do) that becomes immobile as it grows up, and uses pheromones to attract other lifeforms, like something akin to a carnivorous plant. Could that work? Why or why not? Related issues: Is it possible for mammals to undergo metamorphosis? Why or why not? Could, say an elephant, do this without metamorphosis? By no, do you mean not feasible, or could not evolve but could engineer?
[Answer]
Just because it's sessile doesn't mean it can't defend itself.
I have in mind as a starting point some jellyfish that have algae inside themselves--a symbiosis that in effect produces a photosynthesizing animal.
Lets scale this way, way up. The adult form of the creature is immobile. Rather than a symbiosis with algae it's partner is some sort of plant. The plant is taproot-based, the root extends down through a channel in the host and into the ground. The photosynthetic organs (probably not leaves) grow behind a clear protective layer in the host.
While the body of the creature is fixed it retains parts that can move--specifically, some sort of arm or pseudopod. The creature is hexagonal and has 7 such pseudopods--one on top which can deal with birds.
The young are born mobile. When they're grown enough they leave home and find another creature to mate with--this bond is permanent, they take up residence touching their mate and eventually the touching faces grow together. If a youngster can't find a suitable location next to an existing creature they instead pick a suitable location to live and settle in there--they are now the sessile form that another youngster may choose to mate with.
Creatures that are not on the edge of the collection retain only their upper limb and in practice this will lie unused for great periods of time (the birds know not to land there, there will be almost no need to actually defend itself) and become pretty much just energy production and storage.
Since the creature grows by aggregation rather than straighforward growth there's no upper limit on it's size--it will expand until environmental or terrain limits stop it.
[Answer]
One potential (though mildly disturbing) possibility is the logical extension of a [naked mole rat](https://en.wikipedia.org/wiki/Naked_mole-rat) colony. Naked mole rats are eusocial mammals, meaning that the reproductive members of their society and the non-reproductive ones lead different lives (somewhat similar to the way workers and queens in an ant colony are different).
It's not massively hard to imagine a situation in which the females in our new species (let's call it the Couch-potato mole rat) enjoy increased fecundity and lower mobility as they age. Usually a creature losing mobility in old age is just a good way for it to die, but in this eusocial colony setting there is a good reason for the other rats to care for the increasingly sessile Matriarch: namely that she's popping out broods of ratlings like they're going out of style. The logical conclusion of this is a society where the reproductive females find a good burrowing spot, and then all the other rats do the hard work of feeding her, managing her temperature, removing the broods of new rats and defending her. The burrows all around would turn the nearby area into a natural pit trap, and with hundreds of wrinkly little minions hiding in the tunnels, any animal straying there would be certain to have an unpleasant time at the best.
Now: The above answers the question of 'is it possible to have an animal become sessile as it grows up', and gives a potential evolutionary path for it. As for the question of the upper limit for size: That's a beast of a whole different colour. For now I'm going to assume that once a Couch-Potato mole rat becomes sessile it begins to grow until it reaches a nutritional plateau or dies. Mole rats are shown to be resistant to cancers, have extremely long lives for their size and have some very odd metabolic tricks up their wrinkly little sleeves, so that's not outside the realm of possibility.
Looking at the comments of your question I'm assuming that you want these Matriarchs to be visible aboveground, which is a terrible idea as it opens them up to all manner of predation that subterranean life doesn't. It does, however, lend itself well to growth, as the Matriarch no longer has to worry about burrow size or dealing with collapses. For now let's say that when the matriarch breaks ground the non-reproductive males act as warriors, fiercely gnawing at any predator, and hanging onto the hide of their mother to defend against bird predation. Usually this would be a terrible idea, but with the Matriarch popping out replacement soldiers the male mole rats can literally mob predators as they appear, then feed the broken carcasses to their ever expanding mother. If a colony were successful enough then the Matriarch could begin to grow to truly gargantuan sizes, consuming ever more food brought to her by her minions and throwing out even more impressive broods.
Now we start to run into some structural issues. For starters: The mole rat is going to have to remain... accessible to the reproductive males in the colony and to the workers scurrying to remove fresh broods. She also has to be able to eat food brought to her by her minions continuously. This means that her hindquarters can't be covered by the rest of her body, and that the head needs to remain accessible and of such a size that her minions can feed her easily.
This essentially means that the torso is the only bit that can grow: leading to a fat, bloated ball of wrinkly pink flesh. The main structural component in this case is going to be the ribcage, as it's very quickly going to have to bear the brunt of the matriarch's weight. She could lie on her back, but then her reproductive organs would be crushed under their own weight as opposed to hanging down from her spine. Even if she does lie on her back eventually the sheer bulk of muscle needed to breath leads to breathing problems and (as mentioned in your OP) the Matriarch suffocating under her own weight. You can scale up or down as much as you like if we've taken this scenario to this extreme, but I think a sensible size for a fully grown matriarch would be 1-2 meters across, hardly the Behemoths you envisaged.
Though it is one of the more horrifying creature concepts I've thought about in a while. Especially if you cross these rats with [Star-nosed moles](https://en.wikipedia.org/wiki/Star-nosed_mole), and give them a taste for burrowing through flesh...
[Answer]
On land the size is not merely determined by the ability to move around for food, but also the skeletal and skin concerns. In water most of the weight of the animal is supported by the buoyancy of water, but on land there is negligible buoyancy offered by air, so all weight must be supported by the animal's own skeleton.
So while giants like blue whale and megalodon appeared time and again in the oceans, land giants were much smaller (in mass) than them. For example, while there did roam diplodocus and saltasaurus and seismosaurus on land, their weights were lesser (comparatively) than the weights of sea creatures of similar size. In other words, you can say that dinosaurs' were more long than fat. There is little such restriction in the water though.
The first hindrance to a static animal is not how it would get food, but how it would stop becoming the food of other animals. Furthermore, animals' circulatory and digestive systems require at least some movement on the part of animals (anything larger than a cat that is). So even if you have an animals which you continue to feed, it will get sick and die if it doesn't move. This is especially true for mammals. While a boa constrictor would sleep away for most of it's life, a mammal would be much more active.
[Answer]
If you get away from animal life on this planet, evolution might have explored other pathways. The most massive known living organism on Earth is a fungus, measuring about a hundred miles across, growing in the USA prairie. Its fruiting bodies look like insignificant toadstools, but they're all genetically identical and connected underground!
Plants on this planet obtain mobility by having seeds that hitch a lift on (or inside) animals and birds, or blowing on the wind. Elsewhere, you might have plants with autonomous seeds like mayflies or mice, which then take root when they find an appropriate place to bury themselves. If they were voracious predators on other species' small autonomous seeds while they sought a place to take root, you might have a world where animal life never evolved, and sentient forests think long deep thoughts ....
[added later] Another possibility is further evolution of the eusocial insects or equivalents. One mind, very many bodies. I don't know of any insect colonies here on earth that mass more than an elephant or which are anything like as smart as an elephant, but perhaps after we blow ourselves up, it'll be the termites that win in the long term. (It's been written. Charles Stross, "Missile gap", very nightmarish).
[Answer]
Several issues here:
**Why?**
Sessile plants consume a lot less energy than motile animals. So evolutionary pressure for a sessile stage to a life cycle of an otherwise motile creature could arise if the planetary environment underwent a phase in which the energy input available to such motile creatures periodically declined sufficiently to make mobile search for food unattractive energetically. If this were combined with a simultaneous increase in the energy available from photosynthesis then such a lifecycle could be plausible.
**How?**
Mammals do undergo metamorphosis, they just do so *in utero* - in the womb. What we typically think of as metamorphosis occurs ex-utero, after birth. Metamorphosis is to my understanding an hormonally triggered/guided process. In theory mammals could undergo it, I think. However they would need to have the required processes and biochemical pathways built into their ontogony from the beginning. If in the sessile phase they can photosynthesise, then where does this capability come from?
For example, I have in mind a creature which is birthed from a sessile egg and plant combination (OK, lets call it an "eggplant"), in which the eggplant uses photosynthesis to provide the main nutrients and biomass for the new organism. Within the eggplant, animal-like processes (e.g. hetrotrophic processes) consume the biomass created via photosynthesis to create the newborn.
If we assumed an environmental change that makes most motile heterotropic strategies unattractive, then we may also assume that predators of your lifeform also face similar pressures and either adopt a similar sessile stage, or decrease significantly in numbers.
**What?**
In order to fulfil the requirement that this life form is a mammal, I shall specify that the eggplant is 'birthed' from an internal space of the mature mammal-phase. Thus the 'newborn' is actually the eggplant. The "metamorphosis" is the emergence of the adult, mobile phase from the eggplant. The cycle then continues.
I'll leave it to you to fill in the details of how the environment works to drive these processes.
] |
[Question]
[
**This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information.
I'm currently exploring a setting where humans have managed to create traversable wormholes with one critical flaw - something in the wormhole both kills multi-cellular life and destroys electronic systems. The exact cause is unknown, the probes sent in are otherwise undamaged and even a mechanical pencil left in a maintenance hatch survived the trip unscathed.
(If it helps I'm leaning towards the idea that while inside a wormhole everything develops nigh infinite magnetic permeability, erasing all electrical and electrochemical data)
It was this mechanical pencil that inspired the idea of building a probe that utilised a mechanical computer rather than an electronic one. My mind immediately went 'steampunk' but steampunk stories are 'steampunk stories' which was not the intention when exploring this concept (though I'm more than happy to borrow the technology, if not the themes). Not to mention otherwise the tech level is set to today, it's more a revival of technology rather than an alternate path of technological development.
So my question is this, are there any examples of what amounts to a modern version of Babbage's Analytical Engine available today?
[Answer]
You can make a computer out of almost anything though how long such a computer can run and how complex the programs on it can be vary. You can make computers out of [falling dominos](https://en.wikipedia.org/wiki/Domino_computer),[knex](https://www.youtube.com/watch?v=rdT1YT9AOPA) or [billiard balls](https://en.wikipedia.org/wiki/Billiard_ball_computer) if you're so inclined though they can only run very simple, very short programs.
For more serious computers [gears are a good choice](https://en.wikipedia.org/wiki/Mechanical_computer) but you can also use [optical computers](https://en.wikipedia.org/wiki/Optical_computing), depending on the rules about what breaks you may be able to use [rod logic computers](http://www.halcyon.com/nanojbl/NanoConProc/nanocon2.html),[DNA computers](https://en.wikipedia.org/wiki/DNA_computing), [droplet computer](http://news.stanford.edu/news/2015/june/computer-water-drops-060815.html) or [chemical computing](https://en.wikipedia.org/wiki/Chemical_computing).
Computers can be built to use [fluidics](https://en.wikipedia.org/wiki/Fluidics) instead of electronics.
In fact depending on how your computers break you could even have something like a simple fluidics computer which re-writes the magnetic storage of a more complex electronic computer which can then read from some more-durable non-electronic but dense storage medium.
Computer science is no more about actual specific computers than astronomy is about telescopes, you can build something to do computing out of almost anything if you're determined enough.
[Answer]
In this case you probably wouldn't want a full computer. Far too complex. Some thing more like a very fancy clock work toy would be easier.
Your description of the worm hole makes it sound like old film would work as a recording media.
A simple probe could be a camera with a simple mechanical timer and a spring to "jump" the camera back through the worm hole.
Take a look at some of the [complex clocks](http://therumpus.net/2009/11/the-most-complicated-clock/ "complex clocks") and especially for your interest the [chimes](http://longnow.org/clock/chimes/%20[chimes]) and alarms that have been made over the years.
[Answer]
The ultimate Babbage machine was described by K Eric Drexler in his 1987 book "Engines of Creation". This was a "rod logic" device about the size of a bacterium, and Drexler talks about it here: <http://www.halcyon.com/nanojbl/NanoConProc/nanocon2.html>
to give you an idea of where Drexler thought this could go:
>
> 10. Computers from Molecular Mechanical Components
> These computing devices are smaller than the transistors that were commonly in use in computers a couple of years ago by a factor of 104 in linear dimension, which means 1012 in volume. Thus a device of the capability of a single chip microprocessor, like the Z80 or Motorola 68000 made with 3 micron technology, could be put into a volume of 1/1000th of a cubic micron.
>
>
> For random access memory, you should get nanosecond access times with 5 cubic nanometers per bit, or allowing for overhead, a density of about 1020 bits per cubic centimeter. That's more information in a cubic centimeter than people have written down since they started making marks on papyrus.
>
>
> Tape memory gives you another factor of 100 in memory density. Bits would be stored by the presence of a bulky or less bulky side group on a polymer chain, such as polyethylene. To read the tape, you would mechanically probe it to find out how bulky the side group was. The write operation would involve chemical transformation. A reasonable length for such a tape is several microns; a reasonable spooling speed is like a meter per second. To get from one end of the tape to the other is thus a matter of microseconds. We're talking here about tape systems that are far faster than present day hard drives.
>
>
> Estimates of power dissipation are relatively fuzzy. Making a gigahertz clock assumption and assuming a dissipation of 50kT per bit of a 32-bit word per cycle, we're talking of power dissipation in nanowatts. For a single device in good thermal contact with its environment that's a temperature rise of less than a thousandth of a degree Kelvin.
>
>
> Thus a large computer can be small on the scale of a mammalian cell, giving some plausibility if you also assume some other hardware and a lot of software development, to the notion of cell repair systems. Also, yesterday I estimated the computational capacity that you could get in one cubic centimeter using this crude mechanical technology - more computational power in a desk top than exists in the world today.
>
>
> There are a number of papers that discuss this and related topics. If you write to the Foresight Institute [Box 61058, Palo Alto, CA 94306] and send \$5, you can get a packet of papers that describes these things in more technical detail. For a donation of \$25, you can subscribe to the Foresight Institute newsletter "Foresight Update."
>
>
>
[For more up-to-date information, see the Foresight Institute home page. See also Chapter 12 of Nanosystems.]
So if you have the technology to make wormholes, I suspect making bacterium sized supercomputers wouldn't be a really big deal either. If such a device can be made "self aware" is a different question altogether.
[Answer]
>
> (If it helps I'm leaning towards the idea that while inside a wormhole everything develops nigh infinite magnetic permeability, erasing all electrical and electrochemical data)
>
>
>
If that's the case, then have mechanical energy and data storage, but electronic logic.
Punch cards are mechanical, and should survive the wormhole just fine. Heck, CDs are *technically* mechanical storage too. Those ones-and-zeros are stored as little bumps on the surface of the disc.
Mechanical energy storage is easy. Wind-up spring. Us that to unfurl solar panels, and have them bootstrap the rest of the probe.
] |
[Question]
[
In [Can I significantly shorten the days on a planet that can support human life?](https://worldbuilding.stackexchange.com/questions/19728/can-i-significantly-shorten-the-days-on-a-planet-that-can-support-human-life) I asked about changes needed to a planet to support human life with a much-shorter day (12 hours or so instead of 24ish), and learned that speeding up the rotation of an earth-like planet would be feasible. (Answers are divided on whether such a planet should have a moon.) In this question I want to ask about the physical and psychological effects on the humans living on such a planet.
Assume that these are human colonists from earth; they did not "grow up" on this planet but found it in their explorations and settled. They live in structures above ground and spend time outdoors, same as most of us. They're affected by the natural light and the (apparently?) moderated temperatures.
How would this shortened day affect humans over time? Would their circadian rhythm change drastically? Would there be psychological effects, or would it seem normal that you sleep "every other night, plus a bit"? How would their outdoor activities be affected by the shortened day?
On earth we can look at prolonged sunlight and prolonged darkness at high latitudes, but I'm not sure how to research this faster oscillation.
[Answer]
6 hours of daylight, 6 hours of night, twice a 'day'.
Mapped to our 24 hour days from midnight to 6am, it's darkness. From 6am to noon it's daylight. From noon to 6pm it's dark. Daylight from 6pm to midnight. With this schedule, for an office worker in a First World country, one could easily argue that there's no difference.
Waking up for the day happens at approximately same time as on Earth. The morning hours are the same as on earth. There's plenty of light to wake up to. Those people who need lots of light in the morning to get started will be pretty happy. A local adaptation might be to have lunch at "first dusk". Nap time for kids after lunch should be really easy with this light schedule. Perhaps an after-lunch siesta as specified by [NASA](http://science.nasa.gov/science-news/science-at-nasa/2005/03jun_naps/) experience? Office workers who work inside will know that it's time to quit when "second dawn" happens. They then have six hours of daylight to work with for extra-curricular activities. This [graph](http://www.huffingtonpost.com/2014/10/08/sleep-times-america-counties_n_5942296.html) seems to indicate that at least within the US, most people go to bed around midnight. [Madrid](http://travel.cnn.com/after-dark-madrid-535806) seems to be able to make the party last till much later.
This fits well with the slightly modified work/play cycle. Morning people still get their quiet hours of solitude. Night owls get more daylight to work with. Some people are really going to have a hard time with this change because for some reason they are very sensitive to dawn and dusk.
A discussion about whether getting only 6 hours of sleep a 'day' is healthy is a different question.
Based on this scenario, I don't think this 'day' schedule will have a huge impact on human circadian rhythms. Artificial lighting would mitigate the effects of 'second night'.
[Answer]
I think a conflict of circadian rhythms alone would pose significant social and economic difficulties for a human population settling there.
Since the day-night cycle is only 12 hours, by day 2 every human on that planet who followed a 24 hour circadian rhythm (read: everyone) would find themselves developing [shift work syndrome](https://en.wikipedia.org/wiki/Shift_work_sleep_disorder).
While over time the population could get used to the cycle, they still would have to get into the habit of getting less than the 'optimal' 8 hour sleep session per night. That means less time to enter and exit REM, significantly impacting the restfulness of sleep. [The consequences could be many](http://www.theguardian.com/science/2013/feb/25/sleeping-six-hours-night-activity-genes), but the biggest I'd foresee is weakened immune systems. On a new planet, unusual microbes are a certainty, and at the best allergies would run rampant while at the worst a plague would kill even more effectively.
The social effects beyond just sleep could be interesting. To allow at least a consistent day-night sleep cycle, work shifts would be shorter. Add in commutes and the pace of daily life could be hectic. Work productivity might increase, however. Don't they say people only really do 4 hours of work in an 8 hour day anyways?
If an 8 hour workday is followed, it might restore some social balance but the shift work syndrome problem remains. And that could hurt productivity long term.
On the other hand, companies selling coffee or sleeping aids could make a KILLING in this society.
Over time, an indigenous population could of course adapt, but the first two generations might be grumpy and stressed for their entire lives, chugging java and popping pills habitually.
[Answer]
What you describe is very similar to what people go after when they try [polyphasic sleeping](https://en.wikipedia.org/wiki/Biphasic_and_polyphasic_sleep), which is having more than one sleep phase per day.
The general opinion I have seen on it is that people get away with sleeping less per 24 hour period but every now and then end up sleeping for multiple days in a row.
[Answer]
Others have suggested a sleep schedule of sleeping every alternate night which is not too different from our current 24h cycle however an alternative (and perhaps more natural to these people who have never lived on Earth) schedule would be to sleep every 6h night (so twice every 24h).
For issues with lack of REM sleep I believe the human body would adapt over time to compensate for this and this natural compensation would be aided by the shorter day/night cycle.
(See [REM Rebound](https://en.wikipedia.org/wiki/REM_rebound)).
In any case, I think a society capable of interplanetary travel and colonization would have the sufficient technology to adopt appropriate solutions through artificial lighting etc. (Especially lighting more advanced than ours, such that it can accurately replicate natural sunlight)
So in short, I believe human individuals wouldn't really be all that affected by this change especially if they were raised in this environment (it wouldn't really be a **change** to them at all). Human society might be affected in some significant ways such as relatively more significant commute times for a shorter working day.
] |
[Question]
[
A long time ago I heard about a Medieval Irish pirate that used a Trebuchet mounted on his ship (no I am not sure what he was or where I heard it). The idea of a ship acting like a [double pendulum](http://en.wikipedia.org/wiki/Double_pendulum) when firing has always intrigued me and made me laugh. I am assuming that to prevent fouling with rigging it would have to be limited to broadsides with minimal adjustment. I envision it sitting between 2 masts midship.
What sort of design choices would an Age of Exploration Era European Vessel (capable of Atlantic crossing) make to avoid capsizing? Wider, deeper? I am pretty sure a long thin vessel would have an issue with capsizing.
What is a good rough counterbalance weight to ship weight ratio, and ship to ammunition ratio?
Traditionally trebuchets have longer range than mangonel or ballista, what sort ranges would a ship born trebuchet have? Similar to land based of comparable counterweight?
[Answer]
I'm not sure how safe it is to put a trebuchet on a ship. The main problem is probably the counter weight because it is so heavy. As you said, considering the size of a trebuchet (the mast is around 10m long)it's hard to conceive that someone would consider making frontal attack with this. Unless the ship is really long, they would break the mast or something. It might work with sideways attacks but you still need something to stabilize the ship. To improve stability, you could have a ship design multiple hulls, 2 or 3, next to one another.
My other concern is with accuracy. A normal trebuchet on land can fire maybe 3 or 4 times per hour with a well trained crew. On sea, the lack of space and movement of the waves make things more complicated. Not only it take a long time to fire but it's also not very accurate. It require ballistic calculation and a bit of luck. Humidity is a big factor influencing the projectile trajectory as it makes the wood and the ropes less rigid. And don't forget that you are on the water. The boat is always swinging especially when firing. Considering all of this, I have no idea of the range the ship would have but if you can fire it should be about the same. But if your enemy has some trireme (or a similar kind of boat), you won't even be able to fire once.
I am aware that the Romans did put catapults on their ships to attack Cartage but they lost the fleet in a storm and the ships where not really useful in combat anyway. Still, the catapult have the advantage that they do not require a counter weight. They are more compact and less likely to sink the boat.
[Answer]
A trebuchet on a ship is entirely possible. The key benefit is that since trebuchet is a counterweight engine, it can be built to be powerful without shaking the ship apart when it is fired. The downside is that since it is a counterweight engine, it introduces large moving masses to something already unstable. Trebuchets also need to be relatively large to make sense.
The most realistic use would be as a siege weapon. The ship would sail to target, anchor itself securely, remove masts and rigging, assemble the trebuchet on deck and start firing. The ammunitions and the counterweight would double as ballast. The main structure for the trebuchet would also serve as base for the main mast. If the ship only had a single mast, it would be possible to use the arm of the trebuchet as the main mast, but it is probably better not to, as the stresses are different.
The trebuchet would fire lengthwise to avoid capsizing from sifting masses, and the deck would have a lengthwise opening to make space for the arm and counterweight to swing. Basically the arm would swing down enough that loading the trebuchet from the ammunition in the ballast would be easy. The opening would be coverable for sailing. The visible difference would be that since the counterweight needs to swing freely below the point of attachment to avoid breaking the ship, the mast attachment would look unusual.
Also the ship would be rather large since building small trebuchets is not really sensible. Probably a modified merchantman. Large, slow, carries lots of ammunition, has good stability, and is easy to acquire.
A trebuchetship could actually be useful for naval engagements. Many famous naval victories were gained by tricking the enemy into waters where their maneuvers were restricted and they were unable to use their numbers. Large number of ships congested into a small area would make a pretty good target for a trebuchet. Hitting anything would be pure luck, and the rate of fire would be slow, but a ship unlucky enough to be hit by a trebuchet would notice it. But that would be incidental, the intended use would be as a mobile siege weapon for raiding fortified coastal targets.
Also floating trebuchets would be used against the seaside defenses of cities, but those would probably be rafts or barges built on site, not trebuchetships.
[Answer]
With a little Google, I found [a research paper](http://www.doaks.org/resources/publications/dumbarton-oaks-papers/dop54/dp54ch4.pdf) dealing with trebuchets, and it speaks of their use on ships. It only mentions ship-based usage against land-based targets, specifically cities, which makes much, much more sense than using them against other ships--you have no need to maneuvre, and you have a much larger target to aim at. Obviously they made that work somehow. I only skimmed the extract; you might be able to get more detail out of it.
] |
[Question]
[
So, I'm writing a fun bit of fantasy fiction which involves a magic fight taking place on a stone/tile roof. The setup is that two characters are getting pinned down by superior magical fire from a higher vantage point and are in danger of getting overwhelmed. So far it's been fun and enjoyable to write, but I've hit a snag and I can't figure out what should happen next.
I wrote that they solve this by diving into a channel of water on the roof (the water channel is part of a system of channels that distributes water around the buildings, since this is a magic/medieval type setting, that's pretty cool, and the water is brought up magically). The water protects them and they get away into the next part of the fight.
I'm pretty sure that it helps against fire, and would dampen stone fragments and icicles and the like.
However, one of the spells they are being hit with involves lightning. I have a physics background and my first thought was "water is more conductive, so Faraday cage effect", meaning the water provides a better path around then the human bodies and so nothing happens.
On the other hand, landing anything electrical into a bath is a good way to die and the human body is mainly water. And now I'm not sure and I'm doubting myself. So, any help would be welcomed please.
Assumptions:
1. We don't really need to worry about the magic system, it
generates the electricity from a point and that kills people
2. This is not storm
level lightning, rather, it's a zap by an electric current
generated magically (they call it lightning because, eh,
electricity is not a concept there).
3. After generation, the
electricity acts in the ways consistent with the normal laws of
physics as we understand them
4. Assume DC, but working through the
problem in AC would be cool (maybe they've figured it out that it
kills people better, and if so, I probably need to plot that)
5. I'm thinking the energy levels would be
somewhere between 1-10 MW, but I've kinda taken it for granted
that you can use that as an effective weapon (please let me know if
I'm wrong and need to up that figure somehow)
6. The water channel is not big (it's not much bigger than they are)
Thanks in advance for your help!
[Answer]
You need to offer the current something more conductive than the human body, and a path to ground. In fresh water, our salty blood is more conductive. But on a rooftop water channel you can offer the lightning its favorite thing.
**Offer it copper.**
[](https://i.stack.imgur.com/DLdZQ.jpg)
<https://www.marianiroofing.com/cop_proj02.htm>
The roof channels are lined with copper. This makes great sense because copper inhibits algae and microbial growth and will prevent the gutter from getting clogged with this stuff - the image is a rooftop gutter lined with copper than looks broad enough for a svelte action hero to shelter in.
Copper is a phenomenal conductor of electricity. Lightning strikes coming near the characters will go to ground along the copper water channels and leave them unharmed. One of your characters might get the idea because she notices a lot of the lightning seems to be hitting the channel. Your other character does not see why they should go where the lightning is going, but he knows she is usually right and so he grits his teeth and takes it on faith.
] |
[Question]
[
Genetic chimerism is a condition in which a single organism is composed of cells with more than one distinct genotype. In animals, this means an individual derived from two or more zygotes, which can include possessing blood cells of different blood types. Elves inhabit this world, but do not possess magic in this reality. Instead, they are all what can be genetically considered chimeras because they have a strange way of reproducing.
When partners decide to conceive, A male must add his genetic material at different intervals throughout several years to the female. Genetic material could come from a single male or various ones with no connection to each other. The developing child is slowly "built" with the genetic material of one father, or the makeup of several different fathers. After enough "material" has been collected, the embryo becomes fully formed and the gestation process can begin. Because of this, the nuclear family took a different route, with polyandry being more common.
The wife of a household (usually of royal blood or high class individual) would marry multiple husbands. This would usually be two, although wealthier wives might have more if they can support them. These husbands would usually be related (brothers, cousins, etc), but having no blood ties with the woman.
This genetic anomaly among humans is the standard norm among elves. What advantages would this provide to elves as opposed to other single-insemination species?
[Answer]
An interesting question, vaguely similar in some ways to X chromosome inactivation in mammal females (the process that makes a Calico cat patchwork colored, as only one set of genes expresses itself in each location).
There's actually a really great reason why the genetic mixing you propose could be advantageous, and that's the immune system. Some research into human attraction suggests that we are attracted to the pheromones/scent of someone whose immune system is as different as possible from our own. You inherit immunities from your parents, so the more different their immune systems, the more immunities you will inherit. Imagine how much better this system works with multiple fathers?
A couple points of contention might be as follows. First, one might think the immune system is not enough of a reason for such a big evolutionary difference. But this is not the case, several aspects of attraction seem to be based on immune strength (such as facial symmetry and smooth skin). It's such a driver that sickle cell anemia seems to have evolved just to prevent malaria, which says a lot about how bad the disease is if a fatal adaptation is still an advantage.
You might also point out that many of the elves only have one father. that's ok, because many adaptations to nature are subverted by the strangeness of society. But even without the immune advantage, there is an advantage to the child's safety if the parents have a strong long term bond. If a man has to stick around for a long time before he can reproduce, the children have a better chance of surviving and carrying those genes forward.
If anything, this elven system may have more advantages than our own.
[Answer]
**It incentivises multiple fathers to care for the child**
In nature as we know it, many animals evolved to care for their young because that maximises the chance that their genes will be passed on to the next generation. This often leads to two parents caring, protecting and providing for the young (as is common in mammals)
An elf child as you describe has a mother plus multiple fathers who are genetically incentivised (and evolved, probably) to provide care, and therefore a better chance of survival and success, more parents to pay for schoolbooks, food, teach life skills. One deadbeat dad isn't such a problem when you have three other dads. I would expect child poverty among elves to be lower than in a similar human society.
[Answer]
>
> What advantages would this provide to elves as opposed to other single-insemination species?
>
>
>
# Social advantages
Elven society would be more strongly connected, with several fathers caring for the children and for a longer time. If traits can be chosen from the genetic material somehow, as your question seems (to me) to imply, there would likely be a lively "trade" in children makeout - families and clans selecting and breeding for some distinctive traits, valuable traits exchanged between families in political and economic agreements, and so on (something like this appears in early Vulcan history in Star Trek's *Spock's World* by Diane Duane).
# Biological advantages - and caveats
Having chimerism and being able to control it somewhat would lead to faster evolution of traits deemed desirable. This can be a danger to the Elven race (specialization is always dangerous - when the environment you're specialized for changes, you're badly out of luck), but managed carefully and with sufficient foresight, the Elven race could vastly improve itself - strength, stamina, intelligence, resistance to disease.
All of the above involve *controlled* chimerism - if the elves have no saying on what traits gets passed on by which parent, then most advantages disappear.
[Answer]
It increases the genetic diversity within an individual. This reduces the likelihood of [inbreeding depression](https://en.wikipedia.org/wiki/Inbreeding_depression). This is because it reduces the chance of negative recessive traits manifesting. This should make small isolated populations more viable.
It would also make overdominance less likely.
In effect it would give everyone increased chance of "[hybrid vigour](https://en.wikipedia.org/wiki/Heterosis)" and boost outbreeding enhancement. Without needing to constantly outbreed, which would allow you to avoid outbreeding depression.
] |
[Question]
[
This question is heavily motivated by the details of my story, but it has a lot of free parameters to work with. I invite you to think creatively!
**Setting**:
You are in command of a [constant acceleration rocket](https://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration#Constant-acceleration_drives), capable of interstellar travel and your mission is to hop from one system to another 12 ly away as rapidly as possible. Your mission lies in this other system and it is absolutely imperative that you arrive there first, before anyone else.
The great thing about your ship is that you have unlimited delta-v. You can maintain constant thrust or acceleration indefinitely, without losing mass.
Two weeks after you depart, another ship begins the same journey as you. It is essentially the same 'make and model' ship as your own; however, for reasons unclear to you, it is capable of *much* greater acceleration. While your ship's acceleration max's out at 12 gees, the other ship accelerates at a constant breakneck 26 gees. (To simplify my calculations, a 'gee' here is $10$ $ms^{-2}$.)
If not stopped, the other ship will reach the other system before you, with a bit over 2 weeks to spare.
**Plot Details**:
* This is disastrous--remember, for 100% success, you need to arrive first--but it does not create an all-or-nothing scenario. Even if you fail in stopping the other ship surpassing you, you have *something* of a mission to salvage. (Basically, no suicidal action such as a full-on collision is acceptable.)
* You have something of an advantage in that the other ship is strictly pacifist and initially ignorant of the possibility that you might attack it. Left alone, the other ship is comfortable coming within 10 million kilometers of your volume, however, once it learns that you're hostile it will actively avoid you and create countermeasures where it sees fit. It will *not* attack you or take any retaliatory action. You know these things from the outset.
* There is no dialogue between you and the other ship, so no possible negotiation to turn it around or coaxing it nearer. Ultimately, the other ship must be destroyed.
* In your planning, you should consider both what *you* would do, as commander of your own ship, and what the *other ship* (with your very same capabilities, minus the whole berserker acceleration thing) might employ as a countermeasure (if it is capable of producing countermeasures after your first action).
* The other ship will not employ countermeasures until your behavior deviates from the norm, e.g., it observes your trajectory changing unexpectedly, or it observes the radar reflections of many relativistic objects deployed and scattered toward it, and so on. For example, a countermeasure might include intelligence gathering, e.g., deploying arrays of remote telescopes behind itself to observe your activities in detail and make predictions, or a counteractive effort, e.g., shooting at your missiles or the relativistic objects you left along its path.
**Your Capabilities and Constraints**:
(Keep in mind, the other ship has essentially the same capabilities as you.)
* Your ship is a cone 6000 m long and 500 m wide, massing 1 trillion kg. You have two constant thrust rocket engines, each capable of applying a maximum 6 trillion Newtons of force. This gives your 1 trillion kg ship a maximum acceleration of 12 gees ($120$ $m/s^2$). Conveniently, this acceleration is also your ship's structural limit (your ship will break apart if you accelerate *any faster than this*). For make-up, assume the hull and innards of your ship (and consequently the other ship) have a material density of $2.0$ $gcm^{-3}$ and specific heat capacity of $12.0$ $Jg^{-1}K^{-1}$.
* Your rocket engines mass around 10 million kg apiece and are special in that they can only be instructed remotely; they are black boxes that cannot be opened or tampered with. Doing so unleashes a multigigaton explosion. An engine alone can withstand 40 gees acceleration before succumbing to structural stress. The exhaust of an engine is a stew of hot and initially dense matter: excited protons, electrons, and tau neutrinos--not to mention light ranging from radio to gamma-rays.
* Your ship has great industrial capacity and carries millions of tons of raw materials (assume 100 million tons of anything). You can mass-produce structures of any composition (gold, carbon nanotubes, diamond, etc.), and rather quickly. Any technology that *we* (us modern-day people) can hypothesize (with our modern physics) but lack the industrial capacity to manufacture is now on the table for your use with stopping this other advancing ship. (No Clarketech.) Along with your material resources, you have 800 kg of solid [antilithium](https://en.wikipedia.org/wiki/Antimatter) at your disposal.
**Initial conditions**:
* You begin your journey at an unnerving 10 gees acceleration. After two weeks (relative to the origin star system), the second ship sets off.
* From this point, given the information known to you about the other ship and given your ship's manufacturing constraints, you're free to act as you see fit to complete the mission.
**What's at the Destination?**:
* At the destination, you will need to slow down enough to orbit the star (from relativistic velocities, this is basically the same as coming full-stop). You need at least *one* of your black box rocket engines and at least 50% of your ship's mass. (How you go about losing more than half your ship, I haven't got a clue...) You may expend all of your resources destroying the other ship if necessary, including all the antilithium.
**Further Considerations**:
* The living occupants of both ships are more or less immune to the acceleration stresses, but for good measure, assume the maximum stress they can survive extensively is 30 gees. While the other ship is accelerating breakneckedly, the majority of your ship's substrate cannot sustain acceleration greater than 12 gees without tearing like putty.
It may be helpful to keep in mind the arena. 12 lys is a great distance and small changes in direction have enormous effects on *where* in the destination system you arrive (if you arrive *in* it at all). Both ships will therefore tend to lie in some cylinder of space between the two star systems. The other ship will be advancing from behind, however, considerable time will pass (years) before it surpasses your ship. For example, at the half-way point, where your ship rotates 180 degrees and decelerates, the other ship will be about one week ahead of you (if not destroyed). Depending on what you do (accelerate, decelerate, whatever), this point of passing changes.
It may also be helpful to consider the relativistic effects, effects that take place seemingly right off the bat. One month into flight, your speed will be greater than 40% $c$, while one month into the other ship's flight, it is already moving greater than 60% $c$. For help with calculating relativistic variables of each ship, I find that [this](http://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/rocket.html) site and a graphing tool helps.
## The heart of the question is: **What is the best way to engage and destroy the other approaching ship?**
By best, I mean the method that gets the job done with the least expended resources and the least risk of mission failure. For the sake of giving 'destruction' a measure, any hit that affects more than 5% of the other ship's mass can be said to have destroyed it (e.g., vaporizing >5%).
---
One tactic I can see (and that I've seen in sci-fi before) is to litter space around the predicted future path of the oncoming ship with debris. As I alluded earlier, an economic approach might be to manufacture hundreds or thousands of large-spanning, thin light sails and scatter them at random behind yourself, then push them up to speed with lasers into the airspace of the other ship. Because the relativistic energies are so great, collisions would unleash catastrophic energies. A warhead of, say, 1 kg of antimatter, could, under relativistic circumstances, release more energy from its sheer kinetic energy than from the detonation of the explosive itself.
Another tactic might make use of your intelligence surrounding the other ship, which is that it is pacifist and initially ignorant of the possibility you might attack it. Perhaps your plan takes effect when the other ship is nearest and most vulnerable. Maybe you find that some form of a focused beam or laser may be powerful enough at 10 million km distant to vaporize a significant portion of the other ship's hull.
[Answer]
You fire a kinetic kill vehicle with enough fuel and acceleration much greater to that of your opponent.
A KKV is basically a weight with fuel and engines in all directions that is designed to detect and intercept another projectile, usually a nuclear warhead.
This vehicle tracks the immense signature of the opposing ship, and simply puts itself between the ship and its current direction. The kinetic kill vehicle is as stealthy as it can at first.
The opposing ship will move at a certain velocity (say 100.000m/s, random number) when it detects the kill vehicle's exhausts. It will try to avoid the KKV and will use "ordinary" thrusters at first. The opposing ship will gain a sideways direction that will avoid the KKV while continuing to accelerate passed 100.000m/s. The KKV can match the thrusters and moves sideways as well, putting it again in the path. At first small changes in direction will get the opposing ship out of the way easily, but it will also mean it'll need go go around the KKV by a large distance which takes time. Still it passes the first one and puts itself back on track to the destination. The later the opposing ship detects the KKV the more thrust he needs sideways and the more off-target he'll be.
Then it detects a second KKV (or better yet a group of KKV's). You are ahead of your opponent, any KKV with equal acceleration as your opponent will always be between the ship and the destination before the opposing ship can get there. So at some point the opposing ship will have to pass your KKV's to catch up to you, and pass closely to it. The opposing ship cannot try and turn itself and suddenly boost out of the way to pass closely to the KKV as the KKV has at least the same acceleration and can anticipate the much larger targets direction. Additionally a group of KKV's could spread out over a distance so that any direction they try to escape too will be covered by a KKV.
The target has a massive velocity and the KKV only has to wait for the opposing ship to keep accelerating to get the kinetic force differences that would make the collision between ship and KKV a massive fireworks in the early part of the trip. You dont need to use KKV's for the later part of the trip but if you somehow do the KKV's you launched will have half the velocity of your opponent has as he passes that point. So even then the opposing ship can only catch up to you by passing the KKV's especially if they decelerate beforehand.
[Answer]
I've got a number of ideas and this list presents them in the order I would consider them as the commander. I'll however take the liberty of changing one of your conditions and redesign the vessels a bit. You assumed rightly that impacts at relativistic velocities will be devastating and that littering the enemy's path with debris will kill them. However the universe has already littered space for you. Interstellar dust and gasses are a huge issue at some point. Sure matter based impact shields will help you for a while, but they'll be be a destroyed by abrasion and the faster you go, the faster they are gone. You need a non-matter based dust protection system. The easiest solution would be to use point defense lasers to vaporise any dust grain or rock in your path and then to use larger lasers to ionised the gases. Then you use tremendously powerful magnetic fields to deflect, not stop as that would take ten times the energy, the gas away from your ship. An interesting side effect of this is that you are no longer limited by damage to the sacrificial shield, but by the equilibrium of the drag of the gas and the power of your thrusters. Your ships will reach a terminal velocity at some point.
**Laser Strike Against Protection System**
This would be the quickest and cleanest solution to end them. 10 Million km is within the striking range of an array of RBoD's (ravaging beams of death). Striking a target 33 light-seconds away and dealing significant damage might be hard for a single x-ray or gamma laser, but you got years to build an array of free electron lasers or Wakefield plasma accelerators. Their path is predictable, so you can't miss the first shot. Their evasion attempt will take time and your laser strike will have messed up their protection system and sensors. Abrasion will instantly start to take a toll on them. If you are lucky a random dust flake or impacting gas will finish it quickly.
Since I don't like gambling, I would follow up my laser strike with more RBoD fire and a barrage of laser propelled lightsails. Maybe timing the attack in a manner that a rock you already know about, but they don't hits them milliseconds after you disabled their defenses could also work in my favor.
What the enemy commander can do? Nothing once my hostile intentions become clear. Preparation would be key. Don't bring one vessel, bring several. Surprise attacks work poorly against such an armada. Or he could just not moronic ally fly into what is known in this universe as my possible weapons range.
**Hack Their Ship**
You said there's no communication. That doesn't mean that they won't read the messages I send them. This is a long shot by all means, but one that can pay off greatly. An AI-virus withe the instruction "open all airlocks" works wonders on uncooperative spacefarers. After they all suffocated or where killed of by their ship's systems turning hostile, you can board the craft and take it over. You might actually be able to take the enemy crew as prisoners.
The enemy commander could simply keep up strict IT security. But if current behavior of people is any indication, writing into the mail that you're an Nigerian Prince, who wants to give the enemy captain his inheritance and trying 12345 as master password might be worth a shot.
**Other Options**
I've got a number of other ideas. Stealth missiles (check out the ToughSF blogspot (just google it) for the stealth in space is possible series before repeating the mantra of "there ain't no stealth in space"), restructuring you ship to increase integrity and loose mass or using the exhaust beam to fry them would be other options. I just think that the two I presented in detail are the best ones.
**Kinetic Kill Vehicles**
Another answer suggested KKV's as a weapon to use against the other ship. I originally considered KKV's myself, but have thrown them out as they are not as useful as one might first think. To make a meaningful analysis of KKV's we need to know their time to target. Beeing generous, I' ll assume we deploy them at the closest approach, but note that this isn't tactical sound. We want to deploy them as long as they are behind us, making the distance much greater.
$$100G = 74.5 min$$
$$1000G = 23 min$$
$$10000G = 7.5 min$$
$$100000G = 2.4 min$$
$$1000000G = 45 sek$$
While especially the later times look decent, the thermodynamics of such rocket drives are dubious at best. Its either going to be some form of Clarke-Tech, technology so advanced that it can be considered magic, or an antimatter based nuclear pulsed propulsion concept. Fuel, structural and especially radiator mass will impose strict limits on KKV-design. Don't expect a space torpedo, expect a white hot pusher plate, magnets for the magnetic field (the actual pusher plate), huge fuel tanks even with antimatter and a football field sized, red-hot radiator. This KKV's is going to be about as stealthy as the sun in the sky. Even assuming a Clarke-tech drive with the magic ability to ignore thermodynamics, we are talking about an object about as stealthy as your average radio tower. The impact of interstellar hydrogen gas will create this strong radio signal. This is why I propose a laser strike against the point defense and indirectly against the sensor system.
The other differce in assumptions is that the KKV's are apperantly not beeing touched by the pacifist captain. I'd just assume that the KKV's are just eaten up by the dust and rock defence laser, which are essentially a highly sophisticated point defense system. Even assuming that the pacifist vessel doesn't have other weapon system or even blueprints for them (which isn't a forgone conclusion, as the very reason why they might turned pacifist could be that they have such horrible weapon technology that any fighting among themselves is prevented by a mutually assured destruction doctrine and that noone dares messing with their culture because they have a reputation for beeing so good at war that they don't have to fight any more (just some interesting twists for OP)), weaponising any advanced technology is trivial. Just to name a few options for KKV-defense.
* expand the point defense laser grid: More lasers kill more KKV's faster.
* counter missile missiles: Probably the first stage of the defence; the incoming KKV's will be limited in their manoeuvring capability by their own inertia, so the defensive missiles can be lighter and have weaker drives. Even if the KKV's are armored, the shock waves from the impact on the front will all meet up at the rear of the KKV, destroying engines and fuel tanks. In the end mass economics give the pacifists the win.
* [Casaba Howitzers](https://en.m.wikipedia.org/wiki/Nuclear_shaped_charge): These things are amazing for point defense purposes. A wide angle particle beam like this can take out dozens of KKV's in one strike. It trivial to build those with advanced technology.
* Use the Engine: The torchdrives of the rocket is itself a powerful weapon. Op mentioned electrons and protons coming out at what I presume to be a decent fraction of the speed of light. This is a death ray. Just turn the rocket around, my calculations show that the pacifist captain has ample time to do so and vaporise the attacking KKV's. The Pacifists got superior acceleration, so breaking for a few days is not an issue.
I hope that this analysis shows why KKV's will be useless in this scenario.
[Answer]
Option 1: Stop your engines, pretend they have malfunctioned, beacon a SOS on an intercept path with the other ship. When it comes close enough to rescue you, turn on your engines and reduce it to scrap metal.
Option 2: When the other ship is reasonably close, shoot as many unguided masses in various close trajectories on an intercept course with the target (unguided because if they are under propulsion, they will be detectable from longer distances). Something will either hit it, or they will force it to change trajectory enough by altering its acceleration vector to slow it down (significantly, at such speeds). If needed rinse and repeat until you reach the system.
Option 3: Do nothing until the ship is reasonably close behind you, then simply fire off anything and everything that you have at it and its path. Chances are its maneuverability will not fare well under the stresses of relativistic velocity so this is the most certain-kill option.
None of the above have a 100% hit rate, but obviously nothing does.
] |
[Question]
[
A cool thing to imagine would be a world where the land was dominated by megafaunal frog-descendants, as it is/was by mammals today, dinosaurs before the mammals, and non-mammalian synapsids and crocodylomorphs before the dinosaurs.
However, frogs aren't exactly the kind of creature that would be in the position to seize the megafauna niches, compared to other clades like mammals, birds, turtles or squamates. They're not particularly generalistic, poorly suited to terrestrial locomotion and could probably be seriously diminished in the future (due to chytridiomycosis), all that being relative to the aforementioned clades.
So, the playing field would need be leveled to allow them to dominate. However, my question comes here; **what natural extinction event could seriously damage the like of mammals, squamates and turtles, but spare frogs?** Come to think of it, even within Amphibia salamanders would probably be better equipped to rise.
I'm asking this for a friend, who was wondering. Well, technically, he said he'd *be* my friend if I figured this out for him, so no pressure...
[Answer]
Well, amphibians in general already had a run as the dominant species of land vertebrates, although they were also the first so I guess there wasn't much competition for that spot.
So as most other tetrapods are going to be too much competition, we first need to wipe almost all of them out, down to the smallest. This means something like the Great Dying, where most biodiversity is wiped out completely.
In considering what kind of event would work best I think it's useful to make a list of what amphibians in general have going on for them:
* They have a lower metabolic requirements than most other tetrapods, probably tied with reptiles, so they can handle a sudden food scarcity a little better. They also feed mostly on arthropods, many species of which are likely to survive even a massive extinction.
* They can handle the cold better than reptiles while remaining active, but not to the extent of some birds and mammals. However, birds and mammals both rely on their metabolism to keep this advantage, as without it the insulation provided by hair, feathers and fat wouldn't really work. Amphibians have a more passive resistance, some of them even being able to survive freezing, returning active when they thaw.
* They are amphibious. Duh. This however isn't such a big advantage in surviving an extinction event, as most living amphibians tend to live only in freshwater, and ponds, rivers and lakes are going to fare much worse in the face of an extinction compared to seas and oceans.
Considering the previous points, I would suggest the following options. None are flawless and most require very contrived coincidences in order to work, but I do believe that frogs and amphibians in general might survive them and diversity in the following eons.
* Viral epidemic: reptiles, birds and mammals are all fairly close in terms of evolutionary relationships, amphibians are the most removed tetrapod, cladistically speaking. Therefore, if some kind of horrible virus started spreading among say birds, it would have an easier time jumping to reptiles and mammals than to amphibians. This hypothetical virus could cause catastrophic symptoms for long term survival of the aforementioned clades, maybe imparting a mutation that heavily favors the carrier in the short term but dooms it in the long run, allowing it to spread and not be selected against quickly. Meanwhile frogs and other amphibians are just removed enough that the virus doesn't manage to make the jump before most of its viable hosts have gone extinct.
* Terrible global cooling: some kind of super ice age with a fast onset could wipe out most animals from the face of the earth, but a lucky amphibian with a genetic knack for hibernation or an innate resistance to cold might manage to endure the worse winters. Toads and newts are the most likely winners among amphibians. This also has the benefit of removing the amphibians most fierce competition for inheriting the earth, rodents, as small animals actually do much worse at lower temperatures and if this hypothetical ice age happens quickly enough they wouldn't have a chance to adapt. Meanwhile larger animals die simply because they require more food, which will quickly become scarce. I will point out that such an ice age would need to happen like with timing like clockwork in order to work. Too slow and other tetrapods adapt just like they already did in the past. It also needs to last just long enough to avoid making it a TPK for the entire ecosystem. Something like repeated meteor impacts might do the trick.
This is all I can think of, but I will say this: in speculative zoology the "how" is quite often the least interesting part, it rarely holds up to scrutiny and it gets in the way of the premise, so if you want to do Frogworld, do it and drop just a few hints in regards to what made it possible, without going in too much detail.
[Answer]
## Honestly, another meteor, and a bit of luck
I know this is the boring answer, but it seems the most plausible. The reasons mammals were able to thrive after the K-T extinction event is that they could survive off of insects and aquatic plants in the absence of the larger flora the dinosaurs relied on. Amphibians fill a similar role in ecosystems: eating lots of insects. The only edge frogs have over these small mammals is that they serve the first part of their life underwater.
So, if another meteor hit the earth (perhaps one made of a lot of ice to increase the amount of water on the planet), most of the larger animals die off, leaving behind small mammals and reptiles, small amphibians (like frogs), and aquatic or semi-aquatic creatures (just like before). Perhaps one key aspect of this changing world is the abundance of small waters where tadpoles can thrive. Then, because the aquatic creatures didn't suffer as much, it would be better for adult individuals to leave the water (to avoid getting eaten by things like crocodiles). In this environment, amphibians begin to fill the various niches that had previously been owned by mammals.
While this is a possible case, it is equally if not more likely that mammals just take over again. There is really nothing that frogs do better than small mammals after an extinction event other than lay their eggs in water. So you need a world with enough water that having young on land is detrimental to growing populations (as it causes too much competition for land-based food among the young).
[Answer]
A common approach is to just show the creatures that dominate the modern world, highlight their features that are relevant to the plot, and discuss whether those features are well- or ill-suited to the environment. The reader will know from their real-world knowledge that other kinds of creatures might have been possible, but the author has no need point out whether those kinds of creatures never evolved, or whether they died out, or whether they were killed off. If the creatures have extra limbs, it is common for the author to state that multi-limbed sea creatures beat tetrapods to colonizing the land.
John Ringo's series of novels set on Marduk uses this approach. Marduk's native sentients are 6-limbed descendants of amphibians; many of the large creatures are 6-limbed analogs of dinosaurs. The *[Empire of Man](https://www.baen.com/empire-of-man.html)* volume's free sample includes half of the first book, *March Upcountry*.
[Answer]
**Chytridiomycosis saves them.**
<https://en.wikipedia.org/wiki/Chytridiomycosis>
>
> The disease in its epizootic form was first discovered in 1993 in dead
> and dying frogs in Queensland, Australia. It had been present in the
> country since at least 1978 and is widespread across Australia. It is
> also found in Africa, the Americas, Europe, New Zealand, and Oceania.
> In Australia, Panama, and New Zealand, the fungus seemed to have
> suddenly 'appeared' and expanded its range at the same time frog
> numbers declined...] However, it may
> simply be that the fungus occurs naturally and was only identified
> recently because it has become more virulent or more prevalent in the
> environment, or because host populations have become less resistant to
> the disease.
> The oldest documented occurrence of Batrachochytrium is from a
> Japanese giant salamander collected in 1902, although this strain of
> the fungus belongs to an endemic lineage that has not been implicated
> in any mass-mortality events.
>
>
>
The frogs wrestle with this new virulent chytrid, as their ancestors have for millennia. Eventually they come to peaceful coexistence, and the current chytrid adds itself to other "endemic lineages" among amphibians.
Other vertebrates have historically not had such trouble with fungi. Then they do. A pneumocystis-like fungal lung pathogen spreads like wildfire through the vertebrates, infecting and then rapidly killing anything that breathes air with lungs. As with pneumocystis, the natural habitat and mode of transmission of this fungus is not clear but (also as with pneumocystis) it is apparently everywhere. The amphibians survive because many can respire to some extent through their skins, and because their coexistence with chythrids has granted them a measure of immunity.
Besides amphibians, fish do fine. Also some sea snakes survive by virtue of their skin-breathing ability.
[Answer]
Perhaps consider the dual of your solution. Instead of killing off the mammals, give the frogs an extra bonus.
In Australia, Cane Toads are a major pest. They're an invasive species we brought along, virtually invulnerable, and poisonous to boot. They damage the ecosystem by consuming resources and getting eaten (poisoning the mammals). When we were there, some of our drivers would literally swerve out of their way to hit these guys. One of them admitted it was really more for their own satisfaction. The Cane Toads apparently can regurgitate their own guts to survive getting crushed, so they don't always die.
Why did they become such a pest? Because we brought them to Australia suddenly. They have no natural predators. No natural predators is an I-WIN button for most species.
Evolve a frog like the Cane Toad in an isolated region. Then have a major event (earthquake, volcano, etc.) break the isolation. Enter the toads, and they start to take over!
] |
[Question]
[
Right now merfolks are totally envious of us watching a live stream video of cat(fight) via WiFi or satellite internet, ok ok I get it's not the speed but its latency... Urrrr. Nevermind that I sincerely hope that the merfolks can receive WiFi but obviously the signal doesn't penetrate far underwater, any solution to transmit a signal at least matching our WiFi in both strength and coverage without divine intervention and breaking a bank? Note: just work on the transmission of signal, my merfolks can take care of the transmitting and receiving ends themselves.
[Answer]
**Blue whales**
>
> Sound is the most effective way to communicate across a vast expanse
> of ocean – travelling at a speed of five times greater under water
> than in the air - so it’s not surprising then to discover that Blue
> Whales have evolved the ability to communicate with sound across the
> water. ... Due to their solitary lifestyles, Blue Whales have evolved
> an exceptional way of speaking to one another across huge distances.
> As you would expect from the largest animal on the planet, Blue Whales
> have exceptionally deep voices and are able to be vocal at frequencies
> as low as 14 Hz - well below the ability of human hearing - with a
> volume greater than 180 decibels, which makes the Blue Whale the
> loudest animal on the planet.
> <https://www.nationalgeographic.com.au/science/blue-whales-and-communication.aspx>
>
>
>
Transmission of messages through a medium requires two things (1) the carrier wave and (2) the superimposed signal.
>
> A carrier signal is a transmitted [...] pulse or wave at a steady base
> frequency of alternation on which information can be imposed by
> increasing signal strength, varying the base frequency, varying the
> wave phase, or other means. This variation is called modulation. With
> the advent of laser transmission over optical fiber media, a carrier
> can also be a laser-generated light beam on which information is
> imposed. <https://searchnetworking.techtarget.com/definition/carrier-signal>
>
>
>
Think of a child being pushed along in a buggy. The child will soon learn that if they are travelling across a cobbled or other rough surface whilst they are vocalising, the sound will 'vibrate' even if they keep singing the same note.
The merfolk gain the co-operation of Blue Whales in return for favours such as removing barnacles and parasitic fish.
Whilst on duty the whales emit bursts of sound at a constant pitch (the carrier wave) and the mers use a vibrator to superimpose the signal. This sound can travel across huge oceans and be picked up by resonators and the signal decoded.
---
>
> Special acoustic modems that can successfully transmit digital data
> underwater have been developed. These modems convert digital data into
> special underwater sound signals that can be transmitted between two
> submerged submarines or between a submerged submarine and a surface
> ship. These digital signals can represent words and pictures, just as
> on land, allowing submarines to send and receive e-mail. Underwater
> acoustic modems are relatively slow compared to telephone or cable
> modems on land.
> <https://dosits.org/people-and-sound/communication/how-is-sounds-used-to-transmit-data-underwater/>
>
>
>
[Answer]
Is ***wireless*** streaming a requirement? If they just want to stream video from the internet, use cables. We already have a bunch of them across various oceans, and they can probably get less latency and higher speeds if they hijack one of those. WiFi routers are commonly backed by cables anyway...
Also, WiFi doesn't reach particularly far, relatively and practically speaking. A signal that reliably penetrate some 20-30m of water would replace WiFi for your merfolk. That is much more feasible than to get a wireless signal down to Atlantis to begin with. Light or low frequency sound seems like viable solutions here, though the speed might be rubbish.
[Answer]
If you are willing to ignore the opacity of walls then you could transmit signals via near UV frequency light. You would have a usable line of sight range of ~100s of meters (which exceeds most home WiFi units for example). For an example absorption graph have a look at [this](http://www1.lsbu.ac.uk/water/water_vibrational_spectrum.html) site. If the signal light is reasonably bright, and you paint your mer-house walls white or some other reflective colour then you could get around the line of sight issue as the signal could be detected after bouncing off a few walls (but would still need to keep your doors open). Do mer-people need doors in their houses? All this assumes that mer-folk don't see far into the UV.
Alternately you can use ultra-sound as a signal propagator. The information bandwidth will be much lower than with UV, but it [appears](http://resource.npl.co.uk/acoustics/techguides/seaabsorption/physics.html) that even at frequencies of 10^2-10^3 kHz, you could still transmit 10s to 100s of metes, including around corners. So as long as the mer-critters cant hear above a few 10s of kHz that shouldn't be a problem. (Do merm-men/maids use sonar?).
[Answer]
**[S-Waves](https://en.wikipedia.org/wiki/S-wave)**
The idea here is that instead of moving through the water like sound or EM waves, the waves here are generated in the ocean floor in the Local Comms-Node, and come out to whomever wants to connect to the system. A simple tranciever connected to the I-Pod, Cephalopod or whatever would be dropped to the ocean floor (analogous to a Wi-Fi aerial), and you're a handshake away from an afternoon of newsfeeds, browsing Fishbook or the Deep-Trench web of minnow porn and government's dirty secrets:
>
> The S-wave moves as a shear or transverse wave, so motion is
> perpendicular to the direction of wave propagation.
>
>
>
Propagation of a spherical S-wave in a 2d grid (empirical model):
[](https://i.stack.imgur.com/M3Iv4.gif)
*Attribution: Wikipedia 2019 CCSAA [License](https://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_License)*
[Answer]
There was a ***huge*** amount of research going into blue-green lasers and underwater transmission LOS with undersea repeaters for the US nuclear submarine program back in the late 80's early 90's - I knew a researcher through OGC who witnessed a keynote speaker at a conference on this topic get walked away from the podium in their way up to present and told that their research had just been classified and acquired by DOD for that programme.
The intent was to have a good, non RF comms system which was undetectable other than by intended recipients, high efficiency and efficacy, etc etc.
Maybe your merfolks have whopping big naturally-occurring Neodimium YAG lasers with one frequency doubling crystal inline grown into huge genetically engineered chambered nautilus to give off mid green beams at 2" wide and several zillion TeV...
[Answer]
If you have magic in this world, Æthernet connections. When I first wrote this as a comment, I was thinking in terms of our own technology, and thinking that would just be a slightly different name for wired connections. But... magic. It is what you define it to be, and it would make total sense for network connections through the Æther to be able to move around without having to worry about cables moving around within this world at least. There might not even need to be cables, as many universes use the Æther to communicate magically over long distances without *any* tech - but that detail is up to you.
] |
[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/125773/edit).
Closed 5 years ago.
[Improve this question](/posts/125773/edit)
Esperanto itself is mostly derived from/reminiscent of English, Polish, Russian, German, French and various romance languages (or so I’ve heard). In a post-apocalyptic future where the survivors banded together and began to communicate using Esperanto as an easy-to-learn common language, could you expect any of the far-future societies descended from these survivors to be speaking some kind of pidgin Esperanto that’s looped back around to sounding like any of the languages Esperanto is based on?
Something that has different rules and vocabulary but enough of the same sounds that an unknowledgeable observer could mistake it for garbled English or Latin, perhaps?
Or could it even be possible that the language might evolve/devolve into a straight up clone of one of these component languages?
What do you think? How plausible is it for far-future Esperanto to mutate into something that would sound vaguely recognizable to listeners today?
[Answer]
* *Esperanto itself is mostly derived from/reminiscent of English, Polish, Russian, German, French and various [R]omance languages.*
No, it isn't.
The *vocabulary* of Esperanto was made up in such a way as to resemble the vocabulary of Germanic and Romance (and, to a much lesser extent, Slavic) languages; for example, *"birdo"* means "bird", *"kovrita"* means "covered" (similar to the English words), *"mano"* means "hand", and *"kapo"* means "head" (similar to the Romance words). But the *structure* of the language is different, although it still falls in the [fusional](https://en.wikipedia.org/wiki/Fusional_language), [nominative-accusative](https://en.wikipedia.org/wiki/Nominative%E2%80%93accusative_language) pattern typical for the Indo-European family.
(Note: Yes I know that Esperanto can be considered to be [agglutinative](https://en.wikipedia.org/wiki/Agglutinative_language); but it's a particulary mild fusional-like kind of agglutination.)
* *speaking some kind of pidgin Esperanto*
If they speak a [pidgin](https://en.wikipedia.org/wiki/Pidgin) and not actual Esperanto then all bets are off, there is *nothing that can be said* about their idiom. All we can be sure of is that in two or three generations the pidgin will become a [creole](https://en.wikipedia.org/wiki/Creole_language) and start on its own path. In the rest of this answer I will callously assume that you mean actual Esperanto, not some unknown pidgin.
* *Esperanto as an easy-to-learn common language*
Esperanto is not easier to learn than English; nor is it much harder. English has *less* morphology than Esperanto, and for better or worse there are *many more* speakers of English. The only redeeming quality of Esperanto compared to English is that Esperanto has a very regular spelling; but, in its advantage, English has many more songs and stories and movies. It's much easier to learn a language when one has lots and lots of learning material *and examples* of the language being used. How many books are there written in Esperanto? And now many in English? Which language is more useful?
* *Esperanto that’s looped back around to sounding like any of the languages Esperanto is based on*
Esperanto is not "based on" any language. It's an invented language, very unlike anything else on Earth. Or do you mean the *vocabulary* of Esperanto? Vocabulary is *the fastest changing part of a language*.
As for "sounding like"... People with different mother tongues will naturally pronounce Esperanto with an accent derived from their mother tongue; to come back to the examples given above, a person whose mother tongue is English may pronounce *"birdo"* as `['bɝdəʊ]`, whereas a native speaker of a Romance language may say `['birdo]` with clear sonorant cardinal vowels and a distinct "r"; and possibly a long-ish `[i:]` if their native language is Italian or Romanian. But I expect that by the third generation all those accidents will merge into a pretty uniform pronounciation. Whether this common pronounciation will be more similar to General American (with slurred unaccented vowels and approximant `[ɹ]` rhotics) or to Spanish (with clear vowels and trilled `[r]` rhotics) is anybody's guess.
* *Garbled Latin*
Very few people pronouce Latin as the Romans did. In Romance countries, the most common spoken realization of Latin is the so called "[Ecclesiastical pronunciation](https://en.wikipedia.org/wiki/Ecclesiastical_Latin)", which is almost indistinguishable from just reading Latin words as if they were Italian or Romanian words; this is what I was taught in school. Germans normally use a very similar pronunciation, with the difference that they always pronounce hard "g" (they would say `/ger'manus/` not `/dʒer'manus/`), and will pronounce "c" as `/ts/` before "ae", "e", "i" and "oe" instead of `/tʃ/` (they will say `/'tsentum/` not `/'tʃentum/` -- actual Romans would have said `/'kentum/`). The Anglosphere used to have its own incomprehensible pronounciation of Latin, but I don't know whether it is still in use.
Guess what? When spoken by a Romance speaker, or a German speaker, Esperanto already uses the same sounds as Ecclesiastical Latin... And it does sound a bit similar.
* *Could it even be possible that the language might evolve/devolve into a straight up clone of one of these component languages?*
No, no way.
First, there are no "component languages". See above. And then...
No way on Earth for a daughter language of Esperanto to develop the plural in "-s", or the verbal aspects of English. No way on Earth for a daughter language of Esperanto to develop the grammatical genders of Romance.
* *How plausible is it for far-future Esperanto to mutate into something that would sound vaguely recognizable to listeners today?*
Recognizable by whom?
For the next four thousand years or so it will remain recognisable as a descendant of Esperanto, at least by historical linguists. The [Hittite](https://en.wikipedia.org/wiki/Hittite_language) language was spoken some 3,500 years ago and yet it was recognised as (some sort of) an Indo-European language; with a bit of effort it was even understood, and we now have Hittite grammars and dictionaries. We *can read* an Indo-European language three and a half millennia old.
As for listeners not trained in historical linguistics... That's much more difficult and it depends on how far that far future is. For a few hundred years it will remain understandable as Esperanto. After that it will remain recognizable for a few hundred years as very bad Esperanto. After that...
Two thousand years ago English and German shared a common ancestor language; does an ordinary native speaker of English recognize German as *"vaguely recognizable"*? Three thousand years ago the ancestors of the Germanic languages (including English) and Slavic languages (including Russian) were one and the same. Does an ordinary English native speaker recognise Russian as *"vaguely recognizable"*? English and Hindi share a common ancestor language spoken not more than six thousand years ago. Does an ordinary native speaker of English recognize Hindi as *"vaguely recognizable"*?
] |
[Question]
[
**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
---
This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help).
Closed 3 years ago.
[Improve this question](/posts/112387/edit)
This is a submission for the [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798)
[](https://i.stack.imgur.com/7uoM7.jpg)
The Asari are one of the iconic races from the popular Mass Effect games and universe, and while the image above isn't from any official media, it's close enough to what they look like. Besides their biotic abilities, which are fantastic enough to be disregarded here, they are a mono-gender race, reproducing by "melding" with another sentient organic and randomizing their own DNA using the partner as a template. How/why might such a reproductive mechanism evolve, and how might it work?
[Answer]
Step 1: An asari ancestor species had normal sexual reproduction, the species being hermaphroditic. Reproduction was through meetings of two gametes, but it wasn't through mixing of DNA as happens on Earth; the egg contained all the genetic information available to form a zygote, but in a somewhat disorganized state. The sperm-analogue carried protein catalysts that caused the egg's genetic material to organize, with minor variations in the final genetic code based on slight differences in the protein catalysts. When the zygote matured, it produced slightly altered catalysts due to its slightly altered genetics compared to the "female" parent.
In essence, genetic traits are passed on not by mixing material from both parents, but by passing on how the material from one parent (the "mother") is organized by the other (the "father").
The proto-asari also have organelles that can detect very weak electromagnetic fields, and can produce their own electricity to sense other life forms (as some species of fish can). They use this like other animals use scent to identify potentially compatible and fertile mates, and mutual EM stimulation becomes a part of proto-asari reproduction.
Step 2: Parthenogenesis takes place in some individuals. They no longer need to mate, and can use the protein catalysts they produce to "fertilize" their own eggs. However, as the catalysts are produced using their own genetic information, a fertilized egg's genetics are identical to that of the parent (excepting the odd mutation). Just like some parthenogenetic lizards and fish require simulated sex in order to reproduce, the proto-asari still need the EM stimulation in order to trigger reproduction.
Step 3: Parthenogenetic individuals evolve the ability to epigenetically alter their production of protein catalysts. This alteration gets tied into the proto-asari's EM sense. The proto-asari re-invent sex. They can use the weak electromagnetic field produced by another proto-asari to affect the proteins catalysts when they self-fertilize. Without the need to physically transfer chemicals from one to another, the "male" components of the physiology are eventually lost.
Step 4: Eventually, the asari are found by the Protheans. The Protheans not only alter them in order to give them biotics, they tweak them so that asari reproduction can be stimulated by the EM fields generated by the brains of other intelligent life forms, and give them some unconscious control over protein catalyst synthesis. When the stimulation takes place, the asari unconsciously produces the protein catalysts that will replicate something of what they perceive in the other species.
**Edit**
I just realized a different model; in advanced Thessian species, they have a mitochondrial-like organelle with its own genetic material and coding that instead of being involved in energy production is involved in the transcription of the cellular DNA-analogue during duplication. Original reproduction involved the "male" providing the organelle which entered the egg and allowed mitosis to take place. It's differences within the organelle's genetics that cause differences in the way it transcribes the cellular genetics, causing variations to arise. Everything else in the proposed evolution proceeds as I described, with Step 3 being the epigenetic alteration of the organelle's genes.
[Answer]
>
> "Why might such a reproductive mechanism evolve?"
>
>
>
This belies a fundamental misunderstanding of evolution. It replaces Evolution with Lamarckism, a key competitor with Evolution until Science managed to collect enough evidence that Lamarck's theory wasn't supported by observation of the world.
Evolution is the apparent adaptation of organisms, where adaptation is not driven by a purpose; but is a leftover of the organisms that adapted in non-successful ways dying out.
>
> How might it work?
>
>
>
It depends. Being a fictional character, one is not bound to real world observations based in known Science. But, there are real world reproductive oddities, that we might draw inspiration from.
* Yeast / Fungus
These animals merge their cell walls together, leading to multi-nucleated cells where each individual nucleus carries a copy of DNA.
* Bacteria
Bacteria can "conjugate" transferring one's replicated DNA into another's cell. This conjugation may lead to a hybrid organism that is genetically distinct from both original organisms.
* Hermaphrodites
These types of organisms carry both sets of gametes, such that they are technically both male and female simultaneously. Typically they are protected against self-procreation, and sex occurs normally, with one or both organisms becoming pregnant.
* Assisted genetic recombination
Viruses carry genetic payloads that become incorporated into the cell's protein production pipeline. For some of the viruses, those payloads include helper proteins that splice the DNA into the organisim's own DNA.
* Plasmid DNA transfection
Plasmids can deliver their DNA to a cell, infecting it with foreign DNA. The process is known as transfection.
* Environmental uptake
Small cellular organisms sometimes pick up bits of DNA and incorporate them internally without breaking it down to basic Nucleic Acids.
>
> How might it work (round two)
>
>
>
Since the mechanism is described as "rearranges their own DNA according to another's template" it is unclear if reproduction took place. Normally, to reproduce, you clearly have a second organism at one point in time. An organism that rearranges it's own DNA hasn't produced a second organism.
Assuming that this "rearrangement" is compartmentalized to a portion of the organism which is destined to become a new organism, you have a near standard formula for sexual reproduction.
You see, it's not the presence of DNA that is significant in Biological organisms. It is the information encoded within the DNA. Due to some ancient event, we carry around additional copies of what we need to survive. Sexual reproduction is where our offspring lose (at least) one of the copies and gains a (likely) new copy. These copies are inexact, which gives sexual organisms a faster route to reordering their information than non-sexual organisms.
Depending on what is being rearranged, it is unclear to me if this organism would even need special consideration to fit in as a rank-and-file biological hermaphrodite.
>
> How might it work? (round three)
>
>
>
Our current understanding of DNA is tightly tied to it's replication and production of mRNA which is further transcribed into proteins. This occurs with linear DNA, where parts of it actively create proteins.
Assuming we take "rearrangement" to not mean rearrangement of alleles (the possible alternate variations found at a gene site) but rearrangements of the DNA itself, then the organism might
* have very tiny genes, such that rearrangement never splits a gene required for survival. Even then it's a statistics game, large number of combinations would result in dead offspring.
* have a mechanism where genes are rearranged but in ways that are guaranteed to not be split. This has some interesting promise, but the discovery of "homeobox genes" or genes that activate and deactivate regions of other genes would not work properly, likely leading to a dead organism.
homeobox genes are partially responsible for making sure your muscles are comprised by tissue that's muscle instead of bone, blood, nerves, hair, skin, or some other tissue. Genes jumping into and out of homeobox regions would have as big an impact on the organism's growth as genes being split into two non-properly working regions.
* have a mechanism that assured that regions controlled homeobox genes were not rearranged. This idea sounds great, but is very unlikely. It basically presupposes that the organism being born knows how to avoid being born with birth defects. No organism can decide a proper course before it exists.
* have a modular inter-celluar structure, such that the location of the gene doesn't impact it's utility. Sounds great, but just ignores the gene getting split into two nonfunctional pieces by "begging the question" or "assuming a scenario where the failure can't occur because you've defined the scenario to exclude the failure conditions"
>
> How might it work? (final round)
>
>
>
Currently history, which includes luck and chance, has shown that typically sexed organisms dominate the larger species. That is because they are more effective in having offspring that has a wider range of DNA recombination. This wider range permits more members of the species to survive.
We have natural hermaphrodites in nature today. For one reason or another, the chance for them to dominate the environment has not been realized. Sex based organisms are more successful in the Animal and Plant based kingdoms. It might be due to luck; but, it may also be that any specific organism that doesn't have to carry around two sets of reproductive organs has an advantage in living to adulthood.
[Answer]
**The Asari genome is an aftermarket add-on.**
[](https://i.stack.imgur.com/kjqE1.jpg)
Here is the Atmosphere Demolisher spoiler, featured by a number of different model cars. Imagine if the possession of a bigass spoiler like this made the car an Asari car, regardless of the make or model. I propose that is how the Asari genome works.
It is not an outrageous proposition. The Y chromosome is basically an aftermarket add-on that turns the base human model (female) into a male.
It makes for interesting reading, the Y. <https://en.wikipedia.org/wiki/Y_chromosome>
The Y chromosome is tiny and degenerate, representing 2% of total DNA in a human but it is the sole difference between male and female human.
So too your Asari. The tiny Asari genome is an aftermarket add-on. Their reproductive strategy aims at sentient species, and modifies the body plan of that species with a 2% add-on chromosome that makes that individual an Asari.
I gather that in the game, Asari always look like sexy space chicks the males are digging. But the proposed reproductive strategy here would be a lot easier if the other-species mate were a female rather than a male. The biological apparatus for producing children might vary a lot from species to species and a "female" Asari from stock species A might not have the hardware to produce young with mate species B. The whole male thing is to donate some genetic material to something capable of having your children; this strategy would work well with the Asari too.
They could still look like sexy space chicks if you are into that kind of thing. They still might shake it for the males. Reproduction, however, is a different matter...
] |
[Question]
[
There have been more than a few questions covering [Alcubiere warp drives](https://en.wikipedia.org/wiki/Alcubierre_drive), many about what happens with one at FTL and a few about using them at sub-light speeds.
I'm curious about what happens at more pedestrian speeds (tens to hundreds of kilometer per hour as opposed to percent light speed)
**If someone fired up their warp drive underwater what would happen? More specifically, what happens to the water outside and at the boundary of the warp bubble (I'm guessing that the water *inside* the bubble gets moved around much the same as the ship)**
Please ignore the practicality and the general *absurdity* of creating what amounts to a *warp-powered submarine*.
[Answer]
Lots of explosions. Activating an Alcubierre warp-drive isn't recommended for habitable planets, their oceans or possibly even persons of the Alcubierre warp-drive spaceship, er sorry, warp-drive submarine.
Matter, what was formerly water, caught in the compaction volume of the Alcubierre warp bubble could be crushed down to the point where the nuclei of the atoms themselves will disintegrate to radiation. Even if the compaction doesn't go that far, when it uncompacts that densified water will blast outwards. Which looks like an explosion. With or without the massive pulse of radiation if the compaction goes too far.
In the expansion phase of warp-bubble, matter, once again the seawater, will be rapidly expanding outwards. This also looks like an explosion. When the expansion collapses back to normally dimensioned spacetime this could look like an implosion.
In summary, don't try this at home. Don't try this on your home-planet. Not in anyone's ocean, unless you want to do their real estate a lot of harm. This is not taking into account the high probability of destroying your warp-powered submarine. The take-home message is stick to driving your warp-drives in space.
] |
[Question]
[
In my world, magic is based on the use of ***magical words*** passed down as part of a long-forgotten language. The spells are "self powering", they do not cost the user anything.
The catch is that results will vary dramatically based on several factors including:
* The mental state / concentration / emotional state / confidence of the user
* Whether or not (s)he has used that spell before
* Whether (s)he got the pronunciation right
For example, a drunk who has never perform the fire spell before might use the magic word for **burn**, and only set fire to a single blade of grass. Whereas a professional pyromancer who has been meditating for several hours might be able to incinerate an entire army using the same spell.
My question is whether this magic system is chaotic enough to encourage the advance of technology. Or will the presence of magic, however unreliable, still discourage technological advancement?
[Answer]
We can analyze this from a scientific perspective, as technological advancement will look at it from that vantage point. Your system will be viewed as a source of free energy. It either violates the conservation of energy, or at least appears to. That is sufficient for it to be abused.
So the question will be two fold:
* Can an individual generate enough energy via a spell, that it is easier to learn how to properly pronounce the word and use that energy to accomplish what you would have used technology for?
* Is the socio-political climate one which is conducive to large number of people learning these words acceptably? If one takes the dark side approach, the best power is one which is known by you, and nobody else. There may be political forces which encourage casters to not teach everyone the words, forcing the rest of society to use technology.
An interesting side effect might be that casters start obscuring their word amidst others to try to confuse people who might learn by example. Over time, this obfuscation may work its way into the teachings passed down from caster to caster. This might even accidentally obscure the word of power itself, causing it to be lost for all time.
In any case, this system is powerful enough that your story will be dependent on society and politics to contain it. On its own, without limits, it would completely drown technological advancement.
[Answer]
If the enemy in a combat situation can make (preferably non-magic) reasonable actions to break your concentration (eg. loud noises), this could encourage physical weapon development. This would draw other branches of technology too, but, since you can prepare and rest in peace, it's maybe easier to manufacture a machine gun with magic, instead of machining. So to get a technology based industry, you could consider adding some truly random, dangerous factors. (making spells explode sometimes even in the best circumstances.)
[Answer]
I'd say it depends on how many of these words there are, and how complex they are.
If a sober person with a few months or even years of training can reliably pronounce "magical flight for me, these people and those items", there's no need to come up with carts, trains, cars or airplanes. Just get some schooling for the young ones going instead.
If it requires years of studying and hours of meditation to be able to get a reliable "flight for myself and my luggage", that's a completely different animal - the upper class may rely on their magics, but the working people will innovate technologically to make their own lives easier.
Somewhere in between you may end up with magic-augmented technology - steam power that's driven by a certified pyromancer instead of coal, airships being literal ships held aloft by a crew of mages, that kind of stuff. Maybe even mages capable of lightning bolts being employed to generate electricity, Korra style ;)
[Answer]
As long as a magic system is able to be systematized enough to be useful (i.e wiithout a big actually random component), at some point in history it will become a sort-of-science and will substitute some technology unless restricted heavily by scarcity.
Knowledge of a language, skill in its pronunciation and mental focus do not make magic less reliable. They restrict the number of practitioners and the amount of situations where magic is useful.
] |
[Question]
[
Recently when pondering the hypothetical scenario of first contact, the alien race we meet may have very different cultures, ethics, technologies, philosophies etc. to the point that whatever they present are phenomena or things that human languages do not have terms to describe, let alone comprehend, yet. (For example: suppose the extreme case where the alien is a Lovecraftian creature)
But like all ambassadorial meetings between two distinct cultures, communication is important and if a misconception is allowed to grew, it can escalate into conflict very quickly.
By focusing this issue in terms of trying to figure out the alien's language based on what behaviours are considered hostile to them, and which of their behaviours are considered hostile to us, it does seem to be a very complex generalisation of the famous [True, False, Random puzzle](https://en.wikipedia.org/wiki/The_Hardest_Logic_Puzzle_Ever).
Therefore we'll consider that both sides are trying not to screw up communications by trying to make the fewest mistakes possible in learning as much as possible of each other's language and culture:
* What is the most efficient and reliable way to learn a completely foreign language (and its culture) while minimising the potential for life threatening conflict?
* Can logic learnt from the True False Random puzzle be generalised to handle such scenarios?
**Addenum:** Some users might consider that the same type of question could be asked between a developed nation vs an unknown tribe or group, or between humans and another other terrestrial species, or even human communicating with superhuman AI. While the contexts are similar, the degree of tension is very different for the extraterrestrial case as neither side knows the capabilities of the other to harm; whereas in the other cases, there are bases upon which we might guess their capabilities to threaten humans.
[Answer]
There are some things that we assume are going to be true for any species in the universe. $1 + 1 = 2$ will always be true. Large bodies will tend to move toward each other. Any species that has advanced to the point that they can travel through space to reach us will understand these things. They will have the ability to recognize patterns.
Taking inspiration from [The Lageos Plaque](https://en.wikipedia.org/wiki/LAGEOS), it seems reasonable that such a species could determine the pattern shown top and center as a representation of the numbers 1 to 10. If nothing else, it seems like a best bet for bare minimum "first contact" type communication, like electromagnetic pulses.
There may not seem to be much information contained in a message like that, but the aliens could likely deduce that:
1. We are smart enough to count and transmit information deliberately.
2. We noticed them.
3. We want to communicate with them and may be more curious than aggressive.
4. We have base ten mathematics and base two mathematics.
If they let us actually meet face-to-face, we can trade scientific diagrams of universal physical phenomena, like gravity and electromagnetism, and exchange words (or if they're deaf, written characters) that explain what these concepts are called. These will help us to get a grasp of cultural items like notations, orientation (left means forward, right means backward), and etc, and let us gauge each other's advancement in understanding of the universe. We can also get more personal and express that we are "humans" and that each of us has a name.
From there, regardless of difference in culture, we could advance pretty much like any other language. Go grab a pencil, say "pencil." Maybe we should wait to teach them the word for a blaster until they trust us a little more though...
[Answer]
Taking it back to the undiscovered tribes aspect, the first thing is to try and indicate non-aggression.
Some parts of this will likely be universal - for example, it's very likely that being surrounded will imply more of a threat than staying back and sending an individual or small group forward to communicate. Other aspects will be more difficult and depend on knowledge of each others' weapons and capabilities - for example, all human civilisations will understand the principle of pointy sticks being weapons; hence a pointy stick or similar aimed *at* someone is an aggressive act, lowering it is less so, and grounding it could be seen as distinct sign of non-aggression. However, with more advanced weapons the equivalents may not be understood; for example slewing turrets towards an enemy would be well-understood by other people, but perhaps not by an alien race.
[Answer]
I think that an efficient communication depends on how aliens and us perceives and process information / data about reality and about they/us. How do they represent themselves? The time? The space? Do they have / have not thoughts? Do they have/have not ideas about individuality? They can/can't perceive and process environment data as individuals? We are visiting their environment?, we are visited? (Only from technological / scientific / economical perspectives this has powerful implications on how we / they can communicate data / information, how we / they can understand and build systems of communications).
I think that as long as you have a more precise idea about the scenario, this will give you better ideas about the efficient/safest way to communicate for that specific scenario.
I have a wonderful example. Isaac Asimov and The Gods Themselves (I will refer about the Second part but this is also related with the other parts). He have tried to give us some brilliant ideas about how other beings lives in a different universe, and how they is trying to communicate with us, with different systems of perceptions / representations / communications / transformation of the reality, but in the end, I think for a narrative / understandable purpose, similar to us (I think that for Assimov was a pain to write about beings with different system of to process, to think and to transform reality and themselves, without giving to us similarities of "our" reality, but I am sure that it would have been possible for him, but less understandable for us and maybe less "commercial").
BTW, now is presented the movie Arrival (which is based in the "Story of Your Life" by Ted Chiang) is another interesting example about the implications, assumptions, problems and misconceptions of communications with aliens.
] |
[Question]
[
So here's the deal:
In a D&D-fantasy-style world, the continent of Archaon is inhabited by a wide variety of elves, whose physical characteristics vary based on their dwellings. The forest elves are more agile and can camouflage with the trees; the water elves have larger lungs and can swim more easily; et cetera. Some elves, however, decided to go into the caves, and never came out. Over the course of a couple hundred thousand years they evolved. They stopped developing pigments in their skin (unnecessary), they developed larger ears (to hear burrowing creatures), and their eyes had to become more receptive to light.
This is where I'm stuck.
I've done some research into the eyes of underground creatures, looking at things such as the [tapetum lucidum](https://en.wikipedia.org/wiki/Tapetum_lucidum), but I'll confess I'm not very good with biology. So, consider the following particulars:
1. The Cave Elves live deep underground, where there is very, very little visible light
2. Most light that they do view is in the blue-green spectrum, thanks to phosphorescent mushrooms and creatures
3. They began with "standard" eyes, with a pupil, iris, etc.
4. They came to the underground *by choice*, perhaps due to a hostile surface that was more hospitable underground.
5. The caves of Archaon are fairly well stocked, with various plants (fungi?) and burrowing animals (such as large worms) that would provide supplies for the cave elves.
6. Most objects in the world give of a very, very weak "aura"-type energy that could be considered part of the electromagnetic spectrum
Knowing this, *what are some of the most likely biological night-vision evolutions the Cave Elves might develop?* I've considered a few options - cat- or owl-like eyes with the aforementioned tapetum lucidum, albino-like, solid red eyes due to not requiring pigmentation in the eyes, or just plain bigger eyes.
[Answer]
Did their brain atrophy as well? It strikes me that elves overall tend to be fairly intelligent and clever compared to other beings. In the case of at least one video game, the elves were locked up in caves and thus had no option, but to evolve the most basic survival characteristics that would lend themselves to hunting, eating, fighting, etc. in the dark and thus relied on hearing and had no eyes.
If the elves lived in caves by choice and it were important for the cave elves to pass on knowledge of medicine, complex formulas, anatomy, arithmetic, etc. so as to defend themselves from the outside world, or for salvaging outside at night, then some kind of eyesight would be important for survival(cave murals/sketches).
You could always argue that the blue-green light altered the color of their pupil. Larger irises tend to be associated with letting in more light so as to see better in the dark so perhaps the iris is so dominant that the pupil can't be seen at all?
They could have two eyelids: one inner, semi-translucent, and dark eyelid that protected their eyes from any light brighter than the mushrooms(torches, lanterns, the sun), and the outer opaque fleshy eyelid.
[Answer]
They probably wouldn't be blind/eyeless, since there is light from fungus and creatures.
Also, unlike a cave fish, they would probably at times go to the surface just to see what is happening, maybe even do some trading.
Unless they were down in the caves for a very very long time there wouldn't be time for things like larger eyes and ears to develop, but they don't really need to. Most fantasy elves already have exceptional hearing and vision, dark adapted eyes can see a lot in fairly low light, and faint sounds in a silent cave would be magnified.
Being intelligent, they might even use light sources like phosphorescent stuff in a lantern, fire fueled by oil harvested from cave worms, or even elfin magic; `A light in the darkness when all other lights go out`.
One thing that might happen is a sensitivity to the aura around them, used like a kind of sonar.
[Answer]
In one of my less detailed ideas, 200 A.D., humans in Scandinavia began living underground amongst luminous stones, producing enough light to prevent the total loss of their eyes, and they occasionally did hunt on the surface.
Their eyes, when underground, are similar to ours but with comparably big pupils, and irises so large that they remove the whites from view most of the time.
Above ground, their pupils shriveled until it almost seemed that their eyes were just irises and a small amount of whites.
In the case of these *dwarves*, however, some other factor (implied to be a chemical effect of the stones's presence) gave them further mutations as well, leaving it unclear whether the mutation was an effect of the stones or just natural.
My point with adding that last detail is that you should consider how their surroundings could cause mutations in their genes. You said there are glowing fungi and burrowing creatures for them to consume, so their diet is one thing that could have an extreme effect on their bodies and assist in bringing out useful chthonic evolutions.
] |
[Question]
[
In sci-fi we have seen computers, high-tech armour and other technologies respond to a character speaking orders out loud- would an interface that reads a person's brainwaves- basically receiving and responding to commands as soon as said person thinks them- be plausible? And if so, are there any serious potential drawbacks to such an interface?
[Answer]
We already have biofeedback devices capable of reading brainwaves in just this manner, however as they currently operate outside a person's skull, they are very crude and require considerable training to use.
Taking this technology further, if implanted inside the skull, this technology could provide much finer control over more variables with less training.
Ultimately, it can be expected that if taken to its logical extremes, a machine-mind interface would be grown into the recipient's brain and would provide additional abilities that were simply *there* when they were needed, like having an extra *whatever* that felt as if it had been part of the recipient's body since birth.
The ultimate drawback of this might be the dissonance of having abilities appearing and disappearing as the user interfaces with different technologies. It wouldn't be like (for example) having a new eye suddenly appear, and having its field of view overlaid on the field of view of the existing eyes; instead it would bring with it an entirely new field of view and an entirely new set of muscles for moving and focussing it, that the user would immediately know how to use. When the technology was unplugged, the eye *and its field of view* would disappear, unlike someone having their Mk1 eye removed from their skull, leaving an empty field of view. Users would remember having senses and limbs which they simply don't have anymore, and cannot relate to their own bodies until the technology is reattached.
This alteration of the users' sensory-physical environment may cause mental problems, perhaps in all users, perhaps only in particular, susceptible individuals, or it may not be a problem at all. We won't know until we try it for the first time.
[Answer]
In mass production, we have cochlear implants which provide roughly 350,000 people the ability to hear via almost direct interface with the nervous system.
In clinical trials, the Argus 2 bionic eye is being used in 30 patients who are blind, to restore their eyesight using a *camera*. Argus 1 was installed in 6 patients, and as I understand it they all work.
On the bleeding edge, a recent brain-to-brain trial allowed one scientist to *control the other persons hand*, without invasive surgery.
These things are possible because the intermediate hardware doing all the processing can be calibrated by trial and error. Eventually you arrive at a known set of outputs for a given set of inputs.
The basics of the brain-machine-interface you are thinking of already exist, and if you look at them you can see that some of them are voluntary, and some of them are passive sensory input. Thinking rationally about the issue, commanding a set of anime-style battle armor with words that you think doesn't make a bunch of sense - the narrative in your head may engage the ejection seat, when what you intended was to fire missiles.
So it stands to reason this technology will be tempered with some good old fashioned user interface design concepts. Why not actually use the movement of your real arm to command the movement of the armor? We can do that, right now, and work is being done on feedback systems so you can actually feel fingers on a hand that isn't real. That way you can pull the trigger of a unnecessarily large rifle and actually feel it engage.
For less deadly devices, I can absolutely see a wireless brain hookup making for a really great mouse and keyboard. I already spin the mousewheel absentmindedly, and occasionally let sentences get out of control, which I later revise. What would be bad is if my computer shut down because I was trying to type "shut down" with my brain, or if I actually got scrambled eggs every time I kinda wanted some scrambled eggs. I would get hideously fat.
The overall point is that context will always be important. When I have a problem and think bad words, I do not want machinery to give me fertilizer. Whatever happens next in brain-machine interfaces, for voluntary actions, it will need to have a controllable context, and will likely start with something not entirely unlike a command line.
[Answer]
Recently there have been leaps ahead in [implanting microchips](http://singularityhub.com/2015/10/25/scientists-connect-brain-to-a-basic-tablet-paralyzed-patient-googles-with-ease/) into brains to help control computers. In the link, a woman who is mostly paralyzed from [Lou Gehrig’s disease](http://www.alsa.org/about-als/what-is-als.html?referrer=https://www.google.com/) had a chip implanted on her brain. it uses blue tooth technology to connect to a tablet and she can use the tablet and search the web, watch videos etc.
I think it is a huge door being opened for those with disabilities to be able to control their own environment to some extent. Some of what they can do is turn your thoughts to text. Even wearable devices can do some of these things.
Like anything there can always be drawbacks. One they have already experimented with wearable brain reading devices for games to and learned you can 'hack' a brain, they found it was possible to guess at pin numbers and such. Some of these devices they have used to help people learn faster. This could also be used to change peoples mind and thoughts. I heard on NPR the other morning that they can get images of peoples dreams now. If that isn't an ability to read peoples mind, I don't know what is. While this CAN be good it can also be terrible, thought crime might actually be punishable in some dictatorships then.
[Answer]
I was working with a US AF research lab that was experimenting with using brainwaves to fly fighter aircraft. In their open house they took a 12 year old girl from the audience and taught her to fly an F-16 simulator in a few minutes.
This occurred in about 1993.
There were some problems with this process - it kept requiring recalibration or the pilot would get stuck constantly turning in one direction or another. Just before I went to the next presentation the girl got stuck in a left spiral and ended up crashing because the system needed to get recalibrated again.
I'm not aware of any active military unit using this technology even today. Maybe it requires too much discipline? Maybe the human brain meanders too much and using certain brain states aren't constant features of the conscious human mind? I'm not sure why it never caught on.
But it is totally plausible.
[Answer]
Totally plausible, there are already multiple projects testing it. Drawbacks...
Mostly just thinking something you shouldn't and triggering your gear to make something awful happen.
Brain-powered missile launch. Worker asks, "Should we launch it?" Commander says, "no," but thinks about launching it. It launches.
[Answer]
Well there was that quadriplegic woman who [flew the F-35 simulator using only her mind](http://www.wired.com/2015/03/woman-controls-fighter-jet-sim-using-mind/) so I suppose we're getting there.
As to doing action (A) as soon as a person thinks them, I don't think it'll work that way.
In military applications, this would be dangerous and unwise. Weapons release authority, for instance, needs to have a clear chain of responsibility. You can't have a UAV pilot, or a mobile suit pilot, fire that missile as soon as he thinks, 'hmm, lets shoot that fucker down there.'
What I *can* see happening is making the suit an 'extension' of your body. Augmented by the brainwave control, the user moves his armor like his moving his limb. Shooting missiles and other weapons would also be like consciously moving his limb. So, you can move your arm, move your finger, and fire your laser. But this is also risky, so I think integrated weapons will still need a separate command like pressing a button on your suit, or blinking at a specific point on your HUD.
] |
[Question]
[
Since there are living beings (like [moth larvae](https://en.wikipedia.org/wiki/Tineola_bisselliella)) which feed on textile fibers (wool, cotton, silk, et cetera), I was planning to introduce a human-sized creature with such feature, plus the ability to feed on artificial fibers as well.
Said creature should have a life cycle of at least 20-50 years, should feed *exclusively* on textile fibers, and would need about the same energy as a human being (~1500-2000 kcal/day).
Is there any scientific biological mechanism which could make this possible?
If hard-science fail in this case, even an "handwavy-but-interesting-solution" on the creature's supposed biology goes ;)
Thanks!
[Answer]
## **Yes, but....**
Wool is mostly [keratin](http://en.wikipedia.org/wiki/Keratin) and cotton is mostly [cellulose](http://en.wikipedia.org/wiki/Cotton) so your creature's protein and carbohydrate needs may be met in this way. However, fats are an essential component of human diets and those don't occur in any significant quantities in wool or cotton.
## **It's the little things**
The human body needs many minerals that cannot be synthesized. Calcium, iron, selenium, and others are needed on a regular basis or basic metabolic functionality may be impaired. No iron == No oxygen transport. No good. Some vitamins and some a few amino acids can't be synthesized either and must be consumed.
## **But my monster is special...**
Building your monster so it can synthesize all the amino acids and vitamins it needs to function still leaves the problem of minerals and fats.
An interesting possibility is to get the needed minerals from the dyes used in the wool or cotton. Perhaps green dyes contain copper as the primary colorant, so when the monster is low on copper, it will develop a powerful craving for green cloth. Dark red or black cloth contains iron.
Further, dirty/used clothing may be more useful than clean clothes as worn cloth have salts, carbs, or some proteins embedded in them. This makes this monster the literal Sock Monster that causes the disappearance of the odd sock after a load of laundry.
Fats could come from oilskins which contain larger quantities of fats than normal cloth. Also, unprocessed wool has lanolin oil on it though perhaps not in sufficient quantity to satisfy any significant dietary needs.
Getting enough calories may prove expensive because wool is definitely not cheap after weaving. Cotton is cheaper but still not cheap when you need it every day. Unprocessed wool and cotton may be a viable food source.
**Junk Food!**
We want junk food! Junk food! Wool and cotton are boring! I'm not sure of the chemistry of how to do this but your monster could use the long hydrocarbon chains found in plastics as stock for conversion to fats. But! Plastics often have some funky other stuff embedded in the so eating too much of them may cause er, side effects. Definitely something you don't want to eat all the time.
Humans and animals in general don't use hydrocarbons as fuel because there just isn't much of it on Earth's surface. Normal carbs, fats and proteins are much more common so evolution made us to consume those instead of higher energy petroleum products. Life is amazingly flexible in what it can use for fuel. You could include a kind of symbiotic relationship between the monster and some gut bacteria that consume the hydrocarbons in plastics then convert them to lipids. (Heh! Antibiotics make you starve by killing off that gut bacteria.)
Checking on Chemistry SE would be a good place to sanity check conversion of long chain hydrocarbons to lipids.
] |
[Question]
[
Lets say there was a life form in a earth-like environment that would go through.. what I can best describe as 'metamorphosis' throughout several separate life forms. It could start out in Phase 1A, after awhile of growing and feeding, it would grow into Phase 2A, which it would probably go off and reproduce, and probably die soon afterward. The offspring would be in phase 1B, which would be very different from 1A (Perhaps 1A was similar to a insect larvae, while phase 1B is more like a tadpole, etc).
After awhile, the offspring would eventually grow into phase 2B, which could be something like a 'nesting phase' and soon afterward it would grow into Phase 3B, reproduce with other Phase 3B's or 2A's of its species, and raise it's young which would be a Phase 1A version of its species, and the cycle would repeat.
What I am wondering is how might this evolve in the first place, and what might be some evolutionary advantages to doing something like this rather than just a linear "metamorphosis" (or whatever you might call this)?
[Answer]
The simplest mechanism for a species to alternate forms between generations is to have a diploid/haploid lifecycle. As per sumelic's comment, see <https://en.wikipedia.org/wiki/Alternation_of_generations>.
To explain what that is, we humans have two full - but slightly different - copies of our genome in most of our cells (diploid). However, when we reproduce, our eggs & sperm have only one copy (haploid). When an egg and sperm joins to form a zygote, the zygote is again diploid.
Your hypothetical species could have a diploid form that produces haploid offspring - rather than producing single-celled gametes, it simply produces an entire multi-cellular being that in a biological sense is a macroscopic gamete (not necessarily called a gametophyte as in the Wikipedia article, as *phyte* implies a plant), which can then get together with another macroscopic gamete to produce a diploid offspring by more traditional sexual reproduction. The macroscopic gamete form may be hermaphrodite, or may have sexually-dimorphic male/female forms.
You may have all diploid organisms producing macroscopic gametes, or only one gender of diploid organisms may produce macroscopic gametes, which then go to fertilise - or be fertilised by - the opposite-gendered diploid form, which still uses single-celled gametes
Such a system may evolve when the diploid form for some reason has difficulties getting close enough to others of its species to reproduce by the more traditional means of single-celled gametes and close-external or internal fertilisation.
As the distances between diploid individuals increases, the necessity arises for the gametes to be increasingly more robust and capable of travelling over longer distances; this leads to multicellularism, and as the multicellular haploid gametes evolve in parallel, they develop their own distinct biology, quite different from the diploid parents.
As for metamorphosis, this is a very common strategy. Metamorphosing species have an advantage in that juveniles and adults can have different habitats and/or food requirements, thus reducing intra-species competition. It is not beyond the bounds of possibility for there to be different juvenile, adolescent and adult forms.
The possibility also exists for juvenile/adult/post-adult morphs in a species which cares for its offspring; the juvenile is just that, the adult lays the eggs or gives birth to the offspring, and the post-adult cares for the eggs/offspring and perhaps also the adult morph, but is no longer capable of reproduction itself. This could be seen as a parallel to the human child/parent/grandparent system, in that grandparents are no longer capable of reproducing, but still provide invaluable assistance to parents in child-rearing and education.
So, in the example in your question, there will probably have been a period in your species' distant evolutionary history when it had only one form or set of morphs, which was [sessile](https://en.wikipedia.org/wiki/Sessility_(zoology)) or slow-moving in its reproductive morph, and did not exhibit clumping. Difficulties in obtaining sufficient proximity for sexual reproduction led to the evolution of more and more mobile gametes, which eventually became multicellular and quite different from their parents, complete with their own growth patterns and metamorphoses.
Once we have the alternation of generations in place, there is no longer a requirement for a sessile reproductive form to *remain* sessile, and evolutionary pressures may have led to the reproductive form remaining motile, while still retaining the alternation of generations.
A's would mate with B's if in the evolutionary history, only the male gametes were motile and the female gametes remained with the mother. B's would mate with B's (either hermaphroditic B's or male/female B's) if in the species evolutionary history, both male and female gametes were released into the environment.
You may have an even more extreme example of this if one of the variants reproduces [parthenogenetically](https://en.wikipedia.org/wiki/Parthenogenesis) into a third form before it then produces one of the other forms.
] |
[Question]
[
On Earth the planet's magnetic poles line up fairly well with the geographic poles. This makes things like navigation very straightforward as all compasses point to (roughly) the north pole.
However there are planets where this is not the case (Uranus for example).
Obviously Uranus is a gas giant but what would be the effect on an Earth-like planet if the magnetic poles were so dramatically different? As I mentioned above navigation would be a lot harder but what other effects would this have on the planet and its climate?
Image sources [Earth](https://en.wikipedia.org/wiki/File:Geomagnetisme.svg)/[Uranus](https://en.wikipedia.org/wiki/File:Uranian_Magnetic_field.gif).
[Answer]
Aside from the movement of the locus for the aurorae associated with the magnetic poles and the difficulties in using the planetary magnetic field in navigation, I don't believe that there would be a great deal of difference between, for example, A world with magnetic poles aligned with the rotational axis, and one where the magnetic poles are not so aligned.
There is ample geological evidence that the magnetic poles on Earth have [flipped](http://en.wikipedia.org/wiki/Geomagnetic_reversal) many times, and during this change there are likely many geomagnetic north and south poles. These events have not been associated with large-scale meteorite impacts or extinction events, so the likelihood is that aside from a period of confusion for animals that navigate by geomagnetism and a spectacular light show around the many magnetic poles, such a change has little effect.
If a pole reversal event has little effect, then permanently offset magnetic poles would have even less effect.
[Answer]
There wouldn't be a great deal of difference. There are only a couple of differences:
### Navigation
Contrary to the asker's statement, navigation would only be marginally harder on such a planet. All you would have to do is set the compass of by so many degrees. The compass point would point in a certain direction, say, northwest, and you could base your navigation off that equally well.
### Aurora
As [Monty Wild](https://worldbuilding.stackexchange.com/a/477/81) has said, the aurora would be set around the magnetic poles, not around the geographical poles.
---
Basically the difference in the magnetic field would be very little. There would be a much greater difference if there were no magnetic field, but that is another question.
] |
[Question]
[
How is it possible to recreate standard units of measure (meter, kilogram, second) with Renaissance-level technology?
A man (let's call him "Traveler") gets transported to a different world, which is very much Earth-like. This Traveler was able to bring a good amount of knowledge from modern day Earth, and this can be very useful because this world's tech level is barely Renaissance. However, Traveler could not bring any material object with him, not even the simplest tape measure. Naturally, this creates problems in recreating newer technology, because all of the knowledge that Traveler has is based on metric system.
Most of all, Traveler is bothered by the gravitational acceleration of this new world. If feels "off" to him, not by much, but he is pretty sure that it can be up to 10% different from Earth's standard 9.81 m2/s.
Would it be possible to accurate measure gravity of the new world? Traveler knows his height, and this gets him within 1% accuracy of the meter, but has no reference for kilogram or second? Traveler can talk to the brightest minds of this new world, and they are open to the idea of conducting experiments, however there are not yet any Galileos among them.
Related question: [How to create precise measurements from scratch](https://worldbuilding.stackexchange.com/q/54144/32451) deals with the same problem, however, in that question starting conditions, as well as criteria of success were different.
P.S. A clarification - Traveler had an opportunity to prepare for this trip and memorize various blueprints and reference materials. His plan was to recreate SI units once he arrived, but different gravity was an unexpected factor which stopped him from being able to accurately recreate kilogram and second.
[Answer]
To measure gravity accurately, you need to be able to measure **both** distance and time accurately.
These two are fundamental measures of existence.
The other fundamental unit that cannot be measured without reference but only defined is mass.
(yes, you *could* quickly count off 6.0221409e+23 atoms of carbon, and know that's 12.0107grams. But it might take you a while)
Almost everything else that exists are merely derivatives of these three things.
Your traveler has a moderately accurate scale for distance (his own height, although if gravity is different that's not so very accurate, his spine will compress or elongate differently!! Also remember you are about 1% longer when you get up from sleep, than you were when you got in bed), and will have to derive a suitable scale for time.
Unfortunately, just about the only absolute constant (assuming all laws of physics cooperate) would be the speed of light. He would need to remember the speed of light, *measure* the local speed of light in arbitrary time units + his known length , and from that derive an accurate measure of time.
I suspect this will take a while, and a lot of effort.
Some quicker approximation, and suitable for the tech level:
Use the speed of sound. He is breathing normally, so can assume atmospheric conditions and compositions very similar to Earth. Using his length, measure off 171.5m from a handy cliff. The time between him making a noise and the echo returning is one second.
[Answer]
You've got it backwards.
He doesn't need to recreate the SI units precisely, at least not until the science and technology is sufficiently advanced.
What he needs is a stick of *roughly* one meter, and a weight of *roughly* one kilogram, and a timer of *roughly* one second.
He probably knows his [arm span](https://en.wikipedia.org/wiki/Arm_span), as this is used routinely to make quick and dirty measurements. If he doesn't know it, then he probably knows that for normally proportioned men, the arm span is about the same as the height. (See the [Vitruvian man](https://en.wikipedia.org/wiki/Vitruvian_Man).) This will give him a meter with about 5% accuracy.
Yes, the question says that he knows his height to the centimeter. Unfortunately, this is just a convention. The height of a person varies by more than 1% from waking up in the morning (when the spine is relaxed) to going to bed in the evening (when the spine is compressed from supporting the weight all day long). Add in a *slightly* different gravitational acceleration...
A kilogram, long time ago, was defined as the mass of a cubic decimeter of water. The modern definition is very much fancier, but it comes to very nearly the same thing. So he has a decent approximation of a kilogram, say ±15%.
He probably knows the rate of his [pulse rate](https://en.wikipedia.org/wiki/Pulse) at rest. If he doesn't, he can take 70 beats per minute, if he is an ordinary man, or 55 beats per minute, if he is an athlete. (If his pulse rate is much different from those values, he will *definitely* know it.)
This will give him a second with ±10% precision.
So he has a meterr which is ±5% of an Earth meter, a kilogramm which is ±15% of an Earth kilogram, and a sekond which is ±10% of an Earth second. Notably, his kilogram has the same relationship to the meter as the Earth kilogram does, which means that all his knowledge about densities of materials still holds.
This is plenty good enough for practical work. His knowledge won't be *exact*, but it will be close enough.
He can measure the gravitational acceleration in meterrs per sekond squared by measuring the weight of a kilogramm; or he can measure it by measuring the length of a pendulum with beats sekonds. Of course, this won't give the gravitational acceleration in Earth newtons, but this would be a useless piece of data, with zero practical importance.
Now comes the hard part: those new units of measurement have to be *used* for all engineering work. But, fortunately, the question does ask about this.
Time passes. Centuries pass, and the society develops science and engineering roughly equivalent to the 1960s or 1970s on Earth. At this point, if they are curious, they can easily determine the relationship of their meterr, kilogramm and sekond to Earth's meter, kilogram, and second, using the ordinary definitions of the Earth units as they were in that timeframe.
[Answer]
Problem extension: He doesn’t really have to recrate the same units.
I’ll explain: In physics, the only thing that is really tied to the units is the constants (they will change values if you change units).
The formulae themselves won’t change. $\sum \vec{F} = m \vec{a}$ will still be true, in your new units of force, mass, speed etc. (as long as your unit system is coherent).
But you suggested constants (though not fundamental ones) like the gravity of the planet might be different.
That means he’ll have to recompute those constants anyway if he wants to use them.
So why bother trying to reconstruct the SI system? Might as well define new units that are easy to compute on that planet (distance relative to the diameter of the planet, temperature relative to the freezing/boiling points of water on that planet, etc.), and recompute the constants in that unit system.
[Answer]
If he knows his height, he can get a reasonable approximation of a meter length. If he knows different ways of counting of seconds ("one one thousand, two one thousand"), he can get a reasonable approximation of a second.
Now all he needs is a string and a rock.
Tie one end of a string to a branch, the other to the rock, and make sure the total length is the meter. Then let it gently swing, and count the seconds it takes to make 10 complete swings (start-out-back). At 1g, a meter-long pendulum has a period of 2.0064 seconds, so 10 swings should take 20 seconds. If it takes less than 20 seconds, the gravity field is stronger. If it takes longer, less gravity.
It won't be much (19 vs 20 vs 21 seconds) for a 10% difference in g, and honestly given the approximations for the measurement of length and time may be drowned out, but it's something. But if it seems to consistently be different in several tests, combined with his feeling of things being heavier or lighter, it could be enough to confirm. And you don't need mass at all to make the determination.
[Answer]
**Length:** Measure your height in advance and use it to approximate a centimeter.
**Time:** Measure your resting BPM in advance and use it, along with a clock to approximate a second.
**Gravity:** Use a long pendulum with length $L$ and a small starting angle and the formula $$T = 2 \pi \sqrt{\frac{L}{g}}$$ to compute the force of gravity. The formula simplifies to get $$g = \frac{4 \pi^2 L}{T^2}.$$
You can compute the value of pi experimentally by drawing circles or by winding a string around a circular pole.
**Mass:** One kilo is the mass of a 10cm cube of water. You already know the centimetre so this is easy.
**Weight:** On Earth one kilo weighs 9.8 Newtons. On the new planet where gravity has strength $g$ the cube weighs $g$ Newtons. So on the new planet a cube with 9.8/g times the volume will weigh 9.8 newtons or the same as the original cube on Earth. Such a cube has side $10 \sqrt[3]{9.8/g}$ centimetres.
] |
[Question]
[
Let's assume the theoretical [quark star](https://en.wikipedia.org/wiki/Quark_star) exists - and humans have found it. There's a planet orbiting it, and for the purposes of my story, I want it to be habitable.
My question is: Can you have a habitable planet orbiting a quark star?
* The planet would have to have a reasonable temperature range
* The planet would be not cause cancer., although this I'm wiling to budge a little on.
* The planet gets light & heat.
* Assume the planet is earth-sized, with a similar makeup.
* Assume 21st century tech.
[Answer]
Quark star:
It may be purely theoretical, but the mass and size limits in the theory are between the heavy neutron stars and the smallest stellar black holes.
A neutron star from ~6000km (radius of the Earth) is m5-m6 barely-visible star-like object (the quark star would be even dimmer). Then again, its tidal effects at the same distance will tear a human body with ~40kg between the head and the feet. Sorry, no planets bigger than few centimeters at this distance (or closer).
On the other hand, an accretion disk around such object can outshine even the original star by few orders of magnitude and is especially bright in wavelengths outside the visible. As in, extra strong radio and x-ray.
OK, put your planet far away and you get a habitabl-ish planet with rather rough climate (the luminosity of the disk varies a lot) and harsh space weather as well.
If your planet is tilted, your seasons will be 100s or 1000s of years long (the orbital period of the planet around the star). Your people may need to migrate in the meantime.
[Answer]
**Strange planets can be very small.**
[](https://i.stack.imgur.com/ZJ1wH.png)
How big could a planet made of strange matter with 1g be? It might be less than a pea. Strange matter is dense.
[Searching For Strange Quark Planets](https://arxiv.org/pdf/2109.15161.pdf)
>
> It is interesting to note that, under the SQM hypothesis, quark matter
> is bounded by strong interaction but not gravity. So, SQM can even
> exist stably in the form of small chunks in the universe. It implies
> that planets composed of strange quark matter can also exist stably
> 8,9. Strange quark planets are very different from normal planets.
> They have a much higher mean density and a much smaller radius, which
> provide us with some effective new methods to test the SQM
> hypothesis... For a strange quark planet, its mean density can be
> as high as 4 × 10^14 g cm−3...
>
>
>
I calculated [here](https://www.ericjamesstone.com/blog/home/gravity-calculator-for-astronomical-bodies-based-on-radius-and-density/) that a strange quark matter planet with density 4 \* 10 ^5 would have a surface gravity of 1.14g and a radius of 0.1 km. That is a surface area of 33 acres. I take away that a strange matter planet can be pretty much any size desired.
The main point of the linked article is that such planets are so dense they can orbit very close to their parent strange quark star - closer than planets made of normal matter. You can put it as close as it needs to be to keep warm which might be very close.
Strange quark stars are like neutron stars in that they kick out most of their energy as Xrays. I here propose that your habitable strange matter planet has an atmosphere (by definition) and just like Earth, that xray-opaque atmosphere will soak up the xrays. The energy from the xrays will be re-emitted as visible light. The heat source will be the glowing sky.
Possibly, if this scenario is not wild enough yet, the strange matter planet can be tidally locked to its sun. Then the planet can serve as a barrier to prevent persons on the dark side from being radiated. No radiation will penetrate the superdense strange matter planet.
[Answer]
Note that your link says a quark star would be found inside a neutron star. For practical purposes this means you model it as a neutron star, the quark interior doesn't matter. Thus your world is a pulsar planet. You've got some serious problems--the energy emission is low which means the habitable zone is close in--which means tidal locking. You've got an eyeball planet, it's only going to be habitable in the twilight zone.
Degenerate stars are not pure. The surface of all degenerate stars is normal matter, then electron degeneracy. That's it for a white dwarf, a neutron star has a further layer of neutron degeneracy. A quark star (if it exists) adds a further layer of degenerate quarks.
] |
[Question]
[
Let's say there's an operation one day producing items from asteroid and lunar material in orbit, and they want to ship goods to Earth. They try making cheap heat shields by processing rock and regolith material. they put the shields on really simple capsules. The processing doesn't chemically change the material, it just sinters it, or melts it and sprays it. They want to beat the price of a ship coming from Earth to collect cargo and take it to the surface.
The simple capsules ditch in the ocean using parachutes. They are just a metal skin sufficient to protect the cargo, a beacon, and parachutes. The heat shield is discarded after entry, the rest is reused. Capsules are disassembled and sent back to the orbital operation.
The operation is able to make shapes of rock particles that can be quite porous, of arbitrary size and shape. The capsule needs to survive entry, we'll say if it survives, whatever it's shipping does too. Cargo mass is 2 metric tons.
**Edit**
I apologize for yet another edit, but the existing answer, while helpful, considered rock and regolith, not rock that's been processed, so I made edits above to be clear that this is about processed rock and regolith.
Also, I searched and actually found a study on this (which really surprised me). It's a [NIAC study from 2012, lead author Michael Hogue](https://www.nasa.gov/pdf/744615main_2011-Hogue-Final-Report.pdf)
So, it seems that sintered regolith will work for this, and the focus changes to the rest of the task of making this cheap. From page 36:
>
> Within the scope of the testing to date, the feasibility of using extraterrestrial regoliths as the
> construction material for atmospheric entry heat shields has been confirmed from the results of
> the acetylene flame and arc jet testing. While some of the arc jet-tested samples were heavily
> ablated, they provided adequate low temperatures on their rear surfaces. These rear surface peak
> temperatures were recorded several minutes after arc jet test termination.
>
>
>
How should the capsule be designed to work best with this? What would be the best way to make use of such capsules to make the full cost of shipping from an operation in Earth orbit as cheap as possible?
[Answer]
A successful ablative heatshield should evaporate as necessary during reentry. It should not break, crack or disintegrate.
The ablative heatshields used for the Apollo mission were made of a phenolic resin carefully injected into a fiberglas honeycomb structure.
The fiberglas disintegrates at a higher temperature than the resin, that is important to avoid cracks within the heatshield.
I don't think there is a cheap rocky material with similar properties. If original rock is used, you have to avoid pieces with hidden fissures or cavities. If the heatshield is assembled using a lot of pieces, you have to fill the gaps between those parts with a heat proof and gas tight material.
A heatshield material should tolerate thermal stress when the outer layers are hot and the inner layer are cold. Brittle materials like rock would crack under thermal stress, you need an elastic and flexible material.
[Answer]
I remember a nice bit from the (marvellous) book Mining the Sky, by John S. Lewis.
There were studies in how to reduce dependency on goods launched from Earth and closing as many resource cycles with in situ lunar resources.
A significant part of lunar regolith is made of ilmenite, mainly containing, among other more minor (albeit valuable) things, titanium, and iron oxyde.
You can start by crushing and sifting your mineral to the required granularity; then cooking it to extract oxygen from it. Of course, my description is extremely short and the engineering problems are not to be ignored but just got yourself a source of oxygen and ultrapure metallic iron. And ultrapure iron has neat mechanical properties not encountered in regular iron from what I understand. We usually use steel because it's way easier to make down there on earth, but from my understanding ultrapure iron would work great.
What's left after you got the nice stuff? Titanium oxide. Rutile.
Rutile is a refractory material. You can mold your rutile grains in a giant microwave oven the shape of a reentry shield, obtaining an instant, quite literally cheap as dirt, reentry shield. I can't remember the name of the guy who performed the experimentation but I can find it again if you want. And voilà, a reentry shield out of industrial byproduct.
[EDIT]: This experiment was performed by Professor Tom Meek, from the University of Teennessee.
And as I said, you also have a steady source of ultrapure iron to build your single-use moon-to-earth reentry capsule.
I haven't touched the subject of ergol for the moon-earth transit but that also can be sorted.
[Edit]: on the top of my head, you can extract aluminum from anorthite, another readily available mineral on the moon, and burn it with oxygen, to launch a rocket. Sure you may find water in permanently shielded craters at the poles and electrolyse it, but we'd probably be better off keeping such a limited and valuable resource (both water itself, and hydrogen which is extremely rare in lunar regolith) where it is rather than using it as rocket fuel, whereas anorthite is maddeningly plentyfull. Besides, the poles make for a suboptimal launch location for rockets.
From asteroids, it would be even easier. A thing like ilmenite would be not dissimilar to the "worthless" slag after you extracted all the easy to extract valuables.
] |
[Question]
[
I'm designing an illness found in a set group of people. Its effects worsen over time. They suffer from various issues such as nose and mouth bleeding, along with some form of anemia, lingering tiredness, dizziness, and vision blur. The intensity of the symptoms varies based on the stage of illness. Symptoms go from a light nose bleeding you could hide in your handkerchief, to as severe as spitting your arteries out while losing consciousness, leading eventually to death. This is *not* a nice illness, as you can guess. The time between first symptoms and death is about several years.
The symptoms described above are relatively easy to find and explain and have more or less real-world inspirations. I have (I think) a believable, not set-in-stone solution so far: some toxins are generated by the body and, mixed into the blood system, reduce blood pressure and efficiency, eventually breaking the more fragile blood tissues and leading to the aforementioned effects.
Still, while imagining it, I wanted to add something very peculiar that is only found in this illness. And you guessed it, it's turning one's eyes green. I could wave the reason behind it away, saying "it's magic science!", however I'd like to know if there could be a relatively plausible explanation before doing such hand-waving. It could also help me if I wanted to explain the inner details later on.
## About eyes' color shift
Here are some details on this peculiar symptom :
* **It starts to appear at a mid-level of the illness**. At approximately the same time, you start to spit blood, and have light to medium dizziness.
* **The color change can affect the iris or/and the "white" part of the eye**. In order of preference, I would like the two, then the white part only, then the iris only.
* **It should not change the color perception** (you don't see green or everything but green, and you don't become blind either).
* **The skin color doesn't really change**, although slight changes are accepted. Indeed, since the skin becomes paler from anemia, it may be easier to see the toxin or whatever is causing that.
* **The change comes gradually as the illness progresses.**
* **The effects can be reversed if the person is cured**. Same as the above point, the reversal can be gradual.
* **At a severe stage, I wish the color to be as close as possible to a deep, "[Forest Green](https://en.wikipedia.org/wiki/Forest_green)"**. If not possible, another deep green or "near cyan" one. I'd rather avoid yellowish or pale colors.
## Additional conditions
**The most important thing I'm looking for is the biological process that would alter one's eyes**. In case you happen to have a scientifically plausible explanation covering all of the processes, that's very nice and sure worth lots of points, but not 100% compulsory. Here are some additional goals, especially if you try to come up with a general solution:
* **The reaction should not cause alone the death of the person**. E.g. : You find a solution needing the heart's cells, but the person should not have a heart-attack afterwards.
* Kind of like the above point, **you should try to keep the other symptoms intact**. Nicer if you can avoid adding new ones too, even though it's cool if you can make them correlate to each other!
**And last but not least, [the simpler explanation, the better.](https://en.wikipedia.org/wiki/Occam%27s_razor)** I'd like to avoid drowning my world's explorers with a convoluted solution composed of 10 successive processes. Also, it's because I'm unfortunately severely held back by my lack of medical knowledge on this one. So please bear with me :).
As a similar real-world case, you may have heard of [jaundice](https://en.wikipedia.org/wiki/Jaundice), which turns eyes yellow. I don't know the exact process behind it, and worse, it doesn't give a clean green color, and it affects skin as well. I also heard of traumas causing color shifts, as well as rare genetical anomalies (Fuchs syndrome, I guess?). However, no source I could find explained the exact processes involved, which would allow me to reuse them for my illness. Also, these health issues are more likely to remove the color (becoming "greyish") than modifying it, as far as I understood.
Hence my question, **how can an illness make one's eyes turn green?**
[Answer]
Human eyes each have their own immune system which is largely independent from the rest of the body. While trauma, dietary changes, aging, and a variety of disease can cause a change in eye color, some of the mechanisms are not well understood.
A real life example of an infectious disease that can cause a persons eye color to change would be the Ebola Hemorrhagic Fever, [although a doctor specializing in ocular immunology said she had no idea why](https://www.nytimes.com/2015/05/08/health/ebola-eye-color-change-mystery.html#:%7E:text=Although%20such%20color%20changes%20are,hue%20are%20almost%20always%20permanent.). The discoloration is also reversible after recovery.
Since the ocular immune system is separate from the rest of the body, there is no guarantee as to how the coloration change will coincide with other symptoms. It may occur in a person who is otherwise asymptomatic, or it may occur after the person has fully recovered.
According to the CDC, Ebola produces all of the symptoms you requested, including inexplicable bleeding (which leads to anemia and hypotension, which in turn lead to dizziness) and fatigue. It also causes stomach pain, nausea, vomiting, and diarrhea.
Ebola has a modestly high infectivity rate and a frightening mortality rate, though viral diseases are prone to mutation and a new strain could be derived to suit your story needs.
[Answer]
I'm kind of winging this, but I think this might be pretty plausible as long as your readers don't have an extensive knowledge of how metals are assimilated and evacuated from the human body.
The main coloration of the whites of the eyes is typically caused by the accumulation of bilirubin, which is the product of dead red blood cell dismantling and is normally evacuated by the kidneys. An accumulation suggests kidney malfunction, which I decided to go with when planning this out.
I figured copper might be a good chemical to work on since some forms of copper oxide have a nice green tint, specifically copper that has been oxidized in the presence of chlorine, yielding the pigment [verdigris](https://en.wikipedia.org/wiki/Verdigris). That's the colour you'll find on the Statue of Liberty and other statues that have been exposed to open air. Admittedly, this isn't forest green. But it is a cyan colour that could probably form crystals in the white parts of your eyes.
To keep it short, here's an idea: have kidney malfunction cause the accumulation of naturally ingested copper in large quantities and have it react with the oxygen in the blood and dissolved chlorine from ingested NaCl (table salt), and accumulate and crystallise in the eyes. This will mean that lots of hemoglobin will have to be created by the body, since copper is stealing the oxygen of red blood cells leading to increased hemoglobin production to compensate. Iron will be in short supply because of this production, leading to anemia. If kidney function is restored, this should stabilise as the less thick blood will be able to dissolve the crystals and evacuate the copper by the kidneys.
**TLDR: Copper accumulates in the blood due to kidney malfunction caused by an overload of toxins. It binds with oxygen (and chlorine for a darker, greener colour) in the blood and the resulting greenish product forms crystals in the whites of the eyes. This causes stress on oxygen homeostasis in the body, so the body produces more hemoglobin, using up its stores of iron and causing anemia, while also increasing blood pressure and thickness which causes further damage. Evacuating other toxins means the kidneys will eventually filter out the copper oxide.**
Shoutout to Chubbyemu for the inspiration.
[Answer]
**It is really difficult to change iris color!**
Green eyes have relatively less pigment than darker colored eyes. One would think that things that affected melanocytes would thus produce green eyes in people all the time. But it does not. Vitiligo can turn all skin white but spares the iris. Certain small molecule cancer medicines like pazopanib or pexidartinib turn even eyelashes white but not the iris. [There is one drug that can darken light irises called bimatoprost.](https://cdn.mdedge.com/files/s3fs-public/CT104002007_e.PDF) There is no drug that lightens intrinsically dark irises.
I was thinking David Bowie eyes on the theory that denervation that damages pupil would also increase pigment. Eyes are damaged by disease, big pupil, and green.
[](https://i.stack.imgur.com/wF7SN.jpg)
<https://allabouteyes.com/anisocoria-mystique-david-bowie/>
However the party line seems to be that Bowie's damaged eye just looks darker because of the big pupil, probably in contrast to his very light undamaged right eye. I am suspicious but damage should mean lack of stimulus to melanocytes in the eye so lack of function so damage should make a lighter eye. In any case if a person starts with dark irises (like most of the world's people but unlike Bowie) it will not make them look darker or green to have a big pupil.
There is one thing that can lighten a dark eye: an overlay of fatty material. This can happen in the common and harmless condition [arcus senilis](https://en.wikipedia.org/wiki/Arcus_senilis#:%7E:text=Arcus%20senilis%20is%20a%20depositing,it%20is%20in%20elderly%20patients.).
[](https://i.stack.imgur.com/b6iZV.jpg)
[source](https://keepyourhearthealthy.wordpress.com/2010/05/11/arcus-senilis-its-probably-not-what-you-think/)
Depicted is a typical arcus senilis - white ring on dark iris. They can apparently sometimes be yellowish.
[](https://i.stack.imgur.com/uZBpw.jpg)
This image is from one of those google book chapters where the [search shows you some stuff](https://www.sciencedirect.com/topics/nursing-and-health-professions/senile-arch) but you cant click thru to the source.
In any case this is the mechanism for your disease and it will work for all eye colors - an accelerated yellow arcus senilis. Circulating fatty materials form a deposit on the iris that builds up as the disease progresses. Maybe these materials deposit in other places of the body too - xanthogranuloma are yellowish green deposits of stuff which can be a sign of disease, or not.
] |
[Question]
[
I'm writing a novel set in a *post* post-apocalyptic world, where society on Earth collapsed a long time ago and has rebuilt itself by the time the novel starts.
I need a reason to keep the people from leaving the planet and using the resources in space. My idea is that there was a world-wide war that triggered Kesser syndrome in the space around Earth, cutting humanity off from space travel for a long time.
Ideally, I'd like to have the events of this novel take place thousands of years after this war that destroyed the world. But I'm not sure how much debris would still be in orbit to threaten space exploration by then.
So my question is, how long could the cloud of debris caused by Kessler syndrome stay in orbit to still be dangerous? Keeping in mind that this debris is not just in low-Earth-orbit but also the higher orbits and this is an extremely dense cloud caused by the collapse of massive space infrastructure.
[Answer]
The only other current answer (by DT Cooper) is factually wrong. He's misunderstood the link he references and so the 30 - 40 years he's quotes has no baring on your question.
## **Orbits**
Lets first understand how orbits work. If there are no perturbations (drag, solar pressure etc.,) then objects will stay in the orbit they start in forever. This is an idealised view of orbits as we're assuming there are no perturbations - in practice this *never* happens.
## Perturbations
These are anything that can alter an orbit, alter doesn't have to mean reduce the altitude/cause reentry - some perturbations can act to have the opposite effect. The key perturbation in calculating how long an object stays in orbit depends on the orbits characteristics - lower orbits are overwhelmingly ruled by atmospheric drag, in higher orbits this can be negligible.
## **Orbit lifetime**
How long an object stays in orbit can usually be simply put down to the drag on the object. Drag decreases exponentially with altitude, so a small increase in altitude results in a significantly longer orbit lifetime. Here's a good rough estimate:
Satellite Altitude Lifetime
200 km 1 day
300 km 1 month
400 km 1 year
500 km 10 years
700 km 100 years
900 km 1000 years
([Satellite orbit lifetimes](https://www.spaceacademy.net.au/watch/debris/orblife.htm))
You can see that an increase of a few hundred km in altitude results in roughly a 10 times increase in orbit lifetime. But as I said this is exponential.. so increasing beyond 900 km would give you more than a 10 times increase. For your question you've asked about objects lasting 1000's of years... so I'd suggest looking at altitude beyond 1,000 km.
## **How Drag Works**
The above data is for satellites, but that's a very specific type of object. Drag is a *force* it's not a velocity - this means that the effect drag has is dependent on the mass of your object. This comes down to F = ma (or for us: a = F/m). But even this isn't a good enough level of detail because we need to know what the drag area (sometimes called cross sectional area, or wetted area) is for your object(s). Drag force is a function of the size of your object - specifically the area that your object takes up when moving through the fluid. If your object is long, thin and flies like a dart then it's drag area is very small, if it's more like a ball then it's drag area is much bigger. Objects at 1,000 km altitude with a very low mass but large drag area (eg, thin pieces of metal plate) could easily deorbit much more quickly than the graph above suggests - this is all due to the ratio of the drag area and the mass.
## **Some final thoughts**
You've said it would be an extremely dense cloud at higher orbits. Have a think about how much mass that might be required for this dense cloud. If your objects are, say, 0.1 kg each at 1,000 km altitude in a range of +/- 1km and covering from pole to pole then you're talking about a volume of 1,368,000,000 km3 (that's 1.3 billion km3). If you want a 0.1 kg object every km3 (which isn't all that dense of a could) then you'd need 136,800,000 kg of mass in orbit - 136,800 metric tonnes. That is unimaginable, even for such a low density cloud. That's not to say a cloud of 1 object per km3 isn't prohibitive to launching more satellites - just be careful when you describe a dense cloud in orbit.
[Answer]
Okay so after doing research it seems to me that your scenario is somewhat unrealistic. According to this, Kessler Syndrome would most likely only last 30-40 years. <https://www.google.com/amp/s/bigthink.com/how-the-kessler-syndrome-can-end-all-space-exploration-and-destroy-modern-life.amp.html>
There is an alternative you can use though. Instead of having Kessler Syndrome stop your post-apocalyptic people from exploring space, use this alternative instead: Orbital Weapons Platform. Maybe in the lead up to the war the great powers created devices that were made to shoot down spacecraft without some type of verification. Since nobody knows how to deactivate them, they stay up there, blasting any incoming ships to smithereens.
[Answer]
This is just a supplementary answer.
As @user6916458 mentioned, this can work if something(s) big were in high orbits.
After that long, however, most anything in the inner areas would have fallen out by then. That would leave the lower orbits relatively safe.
According to @user6916458's chart, anything below 500km should be relatively safe. that would allow Mercury and ISS style missions. Our ISS would probably be near the top of the "safe" area.
The debris field would be like an Oort Cloud for Earth. A CME or asteroid close approach would disturb some of the debris and cause it to loop in to lower orbits like a comet from the Oort Cloud.
The debris field would block access to geostationary orbits (35,786km) and the other astral bodies.
However, even at those altitudes the field will get thinner over time.
Reaching the Moon might be doable again at that time but it would be dangerous. That might lead to a Moon base from which the rest of exploration takes place.
[Answer]
Economics would be a more effective way of preventing people from looking off-planet. At present, nobody is interested because it's way too expensive. A future society with technology to extract any needed materials on earth would have no need to look further than this planet.
] |
[Question]
[
In the story I'm writing, a group of African penguins evolved to be fully upright (instead of having their knees bent like modern penguins).
[](https://i.stack.imgur.com/nxoBT.png)
Now some basic characteristics of these "erect penguins" are:
* 7 feet tall erect bipeds
* Pack hunters (still carnivorous)
* Socially monogamous
* More slender than modern penguins, lacking any blubber
* Powerful legs
* Powerful beaks (used to peck their prey to death)
* Top running speed of 30 mph
* Flippers that are used for balance when running
* Proportionally longer legs than body
* Slightly thinner and longer neck
Given these characteristics, could such a creature exist, and what evolutionary pressures would lead to them?
[Answer]
The reason penguins have their knees above their hips is purely for balance. The kneeling pose means the center of mass is always below the pivot point, giving much added balance, which is needed for slippery surfaces.
When further evolving this away from the polar regions, then a fair few characteristics would change to adapt and increase survivability in the new region. This is of course given that the species survives long enough in the new area to evolve this way, as a slow fat penguin makes for a tasty snack for the African predators.
The added balance is not needed, and speed is favoured to run away from predators. This means the legs will extend, and the knees will indeed be below the hip. This will come with added height, so a longer neck is needed to reach the ground for feeding. With this, a horizontal body rather than a vertical one is preferable as they would near constantly be bending over. This means the upright state of them is questionable.
As for balancing while running, I would rather expect a larger tail rather than the flippers, as the wings are mostly tucked away in most bird species for added aerodynamics. With this, fluffier feathers will be needed to create drag, as a fully aerodynamic bipedal body won't balance very well at high speed. This is less manoeuvrable in water, so I would expect them to swim less or not at all.
Basically what I have just described as an evolutionary prediction, is (as the comments pointed out) an ostrich. You could play with how they look a bit, but it would be best to take them as a base and merge them with the penguin characteristics you would like to retain.
Of course, if you want this to be a sentient species, the dynamic would change. The human-like upright body would not be out of the question, but they would need appendages for tool use. As it is commonly believed tool use was the catalyst for humans to start developing sentience, [they would need the appendages for that.](https://static.boredpanda.com/blog/wp-content/uploads/2018/01/fb_thumb_5a61c47b329f4.jpg) Also they would need a larger head to accommodate the larger brain capacity.
[Answer]
Umm ... **Frame Challenge**
Basically you have just described ostriches. By the time they have done all this evolving, they won't look anything like penguins anymore. They will in fact look like this.
[](https://i.stack.imgur.com/qbtse.jpg)
<https://images.wordseye.com/ws-image-db/2016-6-2/51315.jpg>
] |
[Question]
[
Contrary to popular belief serpentine dragons are not in fact magical or related to the European [wyvern](https://worldbuilding.stackexchange.com/questions/167897/could-my-wyverns-exist) but instead are descended from the [Chrysopelea](https://en.wikipedia.org/wiki/Chrysopelea). some common characteristics of serpentine dragons are:
* are on average 20 feet long
* are not capable of powered flight but instead are able to glide for long distances
* have fins derived from their ribs
* have a pedal like tail for steering
* have claw like scales for climbing
* have above average intelligence compared to other snakes
given these characteristics could serpentine dragons exist and how might they evolve?
NOTE: magic does not exist in my story
[Answer]
**Size is Totally Realistic**
An average length of 25 feet is easily achievable in snakes, as Anacondas regularly reach 18 feet in length, Burmese Pythons reach 23 feet, and the extinct Titanoboa reached over 42 feet. As for weight, anacondas can weigh up to 400 pounds, so that’s about what you should get for your snake dragons.
**Gliding is Possible**
If your serpentine dragons weighed as much as a Burmese Python or Anaconda they would be far heavier than any gliding animal that currently exists, as most of them are but a few ounces. But this does not necessarily mean that you can’t have a 400+ pound glider. Birds of prey frequently resort to gliding flight, and it’s thus very likely that the massive Quetzalcoatlus Pterosaurs were also able to do it, and they weighed hundreds of pounds. The Dragon would definitely have to climb to an elevated position before it could glide.
**Extended Ribs and Paddle Tails**
These have already evolved in snakes, it’s completely feasible.
**Climbing Scales Probably Wouldn’t Work**
The scales and supporting muscles would be absurdly strong to propel a 400 pound snake up a tree, especially given that the snake already has a much more straightforward method of climbing; it will simply use its massive strength to coil and move up the tree. Pythons already climb this way.
**Intelligence**
Having “above average intelligence for a snake” is a very broad field that lends a lot of slither room. Intelligence is a trait that can be selected for, and it could be explained in simple evolutionary terms as simply being more advantageous over time
] |
[Question]
[
In my story there are people with super powers, but they only get to have one. So, if someone’s power is to start a fire, then they can’t also control it once it starts. My problem currently is with the power of flight.
My superhero can fly. She does not have any additional powers, such as super speed or strength. Being up in the air is exactly like standing on the ground. She can deadlift or carry the average amount/weight for a person of her size and fitness level, whether on the ground or in the air.
So, she and another person fall out of a plane and free fall until they reach terminal velocity. She manages to grab the other person, but now she has to arrest their free fall. Basically what happens at least once in every Superman story ever, but Superman has a ton of other powers while my hero does not.
Is this a deadlift situation, so if she could lift this person while both were standing on the ground, then she can stop their free fall using the same amount of strength? Or is she fighting against a force that is impossible for her to counter?
[Answer]
If she can fly carrying a load, it means she can exert a force equal to her weight plus that of the load, against gravity.
The scenario you describe until terminal velocity can be described as an accelerated motion, starting from velocity 0 and ending with terminal velocity v. While this happens they cover a distance h.
Since she wants to stop the fall, it means she has to reach again velocity 0. With her power this can happen only if she is at an height at least equal to h above the ground. If so she will stop before impact. If not, she well hit the ground.
[Answer]
**She doesn't fly. She simply uses her feet.**
Flight is complicated. Let's break this down to something more simple. Your superheroine's power is actually that *she can use her feet on any substance.* For her, the only difference between walking up a flight of stairs and walking to a point above the local park is that in the first instance she's pushing against the stair treads *and in the second instance she's pushing against air.*
Or water... or fluorine gas... or anything else.
This solves the problem of how she can stop someone from falling. From her perspective, she's standing "on the ground." If she could catch a child from the first floor she can do the same thing at 35,000 feet. If she can carry a sack of potatoes, she can do so standing on the Atlantic ocean surface.
But there is a consequence. *She can't fly.* That's not the actual power. So *getting* to 35,000 feet takes time. However quickly she can run 6.63 miles, that's how quickly she can get to 35,000 feet. And if she can't carry that sack of potatoes for 6.63 miles without setting it down... um... she'll have a problem.
*Developing super powers is fun because you need to come up with both the benefits and the limitations.*
[Answer]
She can do it but it is going to be a lot of work.
1. Imagine I have the power to push a car. Dutch puts it in neutral, and steers (sort of), and I push because we have run out of gas. It is work for me but doable. He honks the horn to celebrate my efforts.
2. We are at the top of a hill but in addition to gas we have run out of brakes. It is a small hill but once back on the level, the car is rolling along at a good clip. I hustle around to the front and push backwards to make it stop. Little by little I can slow down the car as I am pushed along in front. Hopefully nothing is behind me. Dutch honks the horn some more.
Your protagonist is in the second situation. She and her load have considerable kinetic energy moving downwards. She must overcome that downward momentum to come to a stop just as I must overcome the momentum of the rolling car to bring it to a stop. She can only exert the force that she can exert and so she will need to exert it over time, slowing little by little just like me with my smoking sneakers pushing back on the rolling car. If she has enough time before she hits and she does not tire out, she can do it.
] |
[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.
Fire is certainly high up on the top ten list of mankinds most useful inventions. It allows for a more efficient utilisation of nutriants, is the basis of chemistry and the material sciences, allowed us to settle the Northern regions, was the main way of storing energy for most of our history and gave us an edge over other competing species. One can hardly contemplate the rise of a technological civilisation without fire, thus making the range of atmospheric oxygen content where fire is useful important for my worldbuilding.
I'm already aware of a number of limits for oxygen levels. If the oxygen content rises above 35% fires won't stop burning and runaway wildfires will keep the oxygen levels at or below this value additionally the human breathing range lies between 0.16 and 0.5 atm.
Especially with the first constraint in mind I'm interested in the range of oxygen content the atmospere of the homeworld of an aspiring technological civilisation can have while fire remains useful to them. Useful means that the use of fire gives them huge advantages in their primitive environment like heating, lighting and cooking without demanding extensive caring (read if one person needs to supply air regularly just to keep the grill going its too much) or being extremely dangerous (if lighting a fire is like opening a gate to a dimension filled with ill tempered fire demons and one spark will annihilate the camp in a fierce cataclysm it is too much).
**What is the range of atmospheric oxygen content I'm looking for? Does partial pressure or fraction of the atmospere matter?**
Use earthlike conditions as your answers baseline, only taking away or adding nitrogen to adjust for the varying oxygen content. Should changing composition or pressure lead to interesting effects feel free to mention them. Thanks in advance guys.
[Answer]
Given that the only [tool using species](https://en.wikipedia.org/wiki/Tool_use_by_animals) we have examples of are forms of Earth fauna that require similar [levels of oxygen to humans](http://www.geography.hunter.cuny.edu/tbw/wc.notes/1.atmosphere/oxygen_and_human_requirements.htm) and tool use is the basis of the only advanced technological civilisation we know of the single-point-of-reference evidence we have would suggest that our current earthly levels are prerequisite for the type of civilisation you want to form.
To answer the question of what levels of oxygen are required to make fire a useful tool, the settlement of [La Rinconada](https://en.wikipedia.org/wiki/La_Rinconada,_Peru) in Peru is instructive, La Rinconada has no fire department because fires cannot get out of control because the [effective 11% oxygen](https://www.higherpeak.com/altitudechart.html) means that fires need constant tending and/or specialised fire places/blowers to keep them burning and there is a distinct limit on the temperatures that can be reached; Gold, Silver, and even Copper can be smelted, with [specialised equipment and techniques](https://books.google.co.nz/books?id=QIFTVWJH3doC&pg=PA240&lpg=PA240&dq=high+altitude+silver+smelting&source=bl&ots=Ye0FGd7PY-&sig=ACfU3U3gZNPzmDts69wj4I-g5zg4I9aDXg&hl=en&sa=X&ved=2ahUKEwjf68es0pjiAhVVg-YKHcB-BjU4ChDoATAEegQIBxAB#v=onepage&q=high%20altitude%20silver%20smelting&f=false), but Iron cannot. Your upper limit of 35% is broadly correct for the carbon based flora and fauna we know. So for general cooking but also to have iron smelting etc... you're looking at something like 0.15-0.3atm partial pressure of oxygen. That 15% lower limit is a bit rough, may be a little higher that it needs to be, but it's an estimate based on the work of J.E. Rehder in *[The Mastery and Uses of Fire in Antiquity](https://www.goodreads.com/book/show/2264910.The_Mastery_and_Uses_of_Fire_in_Antiquity)* and correlates well with the highest altitude Roman Iron smelting sites [found in the Alps at 2000-2200m](https://www.researchgate.net/publication/49132520_Roman_and_medieval_iron_mining_and_smelting_at_high_altitudes_in_the_south-western_Alps_Mercantour_and_Ubaye_Mountains_Alpes-Maritimes_Alpes-de-Haute-Provence_France) which used standard designs that work equally well at sea-level.
] |
[Question]
[
Assuming that there is a means of increasing the spin rate of an existing black hole, what would happen to the shape of the event horizon as the spin rate was increased? In extremis what would eventually happen at very high spin rates? Could an extreme relativistic spin rate destabilise a black hole if the rotational energy imparted exceeded the energy content of the mass?
Assume that an arbitrarily large power source is available to spin up the black hole.
[Answer]
## Prelude
The situation you're considering involves a rotating black hole characterized by the parameters $M$ and $J$, the mass and angular momentum of the black hole. The two are encapsulated in something called the *Kerr parameter* $a$, given by $a\equiv cJ/GM$
where $c$ and $G$ are the speed of light and the gravitational constant. If we define the parameter $a\_\*\equiv a/M$, it turns out that general relativity predicts the condition that $a\_\*\leq1$, or, equivalently, $J\leq GM^2/c$. This is known as the *Kerr bound*.
It turns out that the geometry of a rotating black hole is complicated. There are two event horizons, $r\_+$ (the outer horizon) and $r\_-$ (the inner horizon), given by
$$r\_{\pm}=M\pm\left(M^2-a^2\right)^{1/2}$$
Here, I'm working with [geometrized units](https://en.wikipedia.org/wiki/Geometrized_unit_system) where $G=c=1$ and we can ignore the constants. The equation tells us that $r\_-<r\_+$. Now, if we let $a\_\*>1$, it turns out that $r\_{\pm}$ is a complex number, which is unphysical. This is interpreted as implying a naked singularity, which is widely believed to be impossible as per the [cosmic censorship hypothesis](https://en.wikipedia.org/wiki/Cosmic_censorship_hypothesis). This should give you some physical intuition for the Kerr bound.
## Merging black holes
If I remember correctly, most of the mergers observed by LIGO feature remnants spinning far below $A\_\*$. However, presumably there exist binary systems where the total angular momentum of the black holes is greater than that of the remnant we would naively expect to form. What happens to them?
This seems to be something of an open question, but [it is believed that these binaries would take more time to merge](https://astronomy.stackexchange.com/a/18396/2153), in the process radiating away this additional angular momentum through gravitational waves. It is also possible for this angular momentum to be transformed into linear momentum, thereby imparting a "kick" to the remnant, reaching speeds up to several hundred kilometers per second.
## Observations
Now, we've observed systems where $a\_\*$ is very close to the Kerr bound, but doesn't pass it. [GRS 1915+05](https://en.wikipedia.org/wiki/GRS_1915%2B105) is perhaps the most commonly-cited example, with one group deriving a lower limit of $a\_\*<0.98$ ([McClintock et al. 2006](http://adsabs.harvard.edu/abs/2006ApJ...652..518M)). Different models by the group returned different precise values for $a\_\*$ (although all larger than $0.98$ and less than $1$). I don't think anyone believes that GRS 1915+05 violates the Kerr bound.
The point of this is that black holes with Kerr parameters close to $a\_\*=1$ do exist and are indeed stable. Their event horizons are indeed different from those of non-rotating black holes (as is the case for any rotating black hole, not just those near the limit), so there is distortion but not instability *per se*. Furthermore, binary mergers are not expected to tip a black hole over this critical threshold.
] |
[Question]
[
So I have an alien biosphere [in which trisexual reproduction predominates](http://mercierdavis.com/worldbuilding/trisexual.html). As far as we can tell, trisexual reproduction [does not offer an advantage when it comes to shuffling genes](http://www.xenology.info/Xeno/12.1.htm). The biological mechanics are already explained in detail, so I only need to answer the why.
**Why would the biosphere evolve this way? What selection pressures would favor the evolution of reproduction requiring three individuals over two?** Resistance to inbreeding forced by frequent population bottlenecks? Genetic redundancy that would mitigate frequent exposure to mutagens? Etc.
[Answer]
Note: I did not look at your link before posting this answer. The triple helix system looks quite complicated and somewhat unlikely to evolve naturally from simple chemicals.
Consider the ABC sex determination system for diploid individuals, where A, B and C are chromosomes with a distinct form that can pair up. Each of A, B and C contains a distinctive gene that encodes for a protein necessary for viability, two of which combine to determine the sexual characteristics. Two of the same are too much, the resulting individual is not viable and culled in an embryonic stage. This naturally leads to the forms AB, AC and BC as only existing forms.
Now suppose that the chromosomes also encodes other proteins that, apart from the sexual characteristics, also have a great impact on the morphology of the creatures. For instance, chromosome A holds genes that induce a (far) greater size and territorial protection, while form B induces more muscles and form C promotes intelligence. This leads to:
* AB: big, strong and dumb and quite territorial
* AC: big, weak, smart and quite territorial
* BC: small, strong, smart and not territorial at all
Individuals produce gametes of either kind without differentiation among the gametes of either chromosome type (A, B or C) or source of the individual (AB, AC or BC) and further suppose the actual reproduction is performed by pooling a bunch of gametes in an aquatic environment with sufficient nutrition, like terrestrial fish. The following options present themselves:
* asexual reproduction, just the gametes of a single individual. 50% chance of producing what is essentially a clone
* bisexual reproduction, the gametes of two individuals of same sex or different sex. Again 50% chance of producing offspring, half of which are essentially clones
* trisexual reproduction, the gametes of three individuals, two out of three individuals of the same sex again gives a 50% chance of producing offspring with less likelihood of clones, three individuals of different sex gives a 66% percent chance of producing offspring with less likelihood of clones.
As the latter option, three different sexed individuals pooling their gametes produces more offspring with a balanced mix of sexes this is the favored option, especially if the chances of survival of an embryo or larva are quite slim, but approximately equal for all three sexes, again not unlike terrestrial fish.
[Answer]
In our cells we have mitochondria which do a lot of work producing energy etc, but they were not originally part of the cell. They were a separate organism that evolved.
A similar thing could happen on larger scales, let us say that a species has a normal 2-parent breeding system. However it has also co-evolved with a symbiotic organism that lives inside it and is vital in some way to the life of the species.
When breeding two parents create the new lifeform - however something else needs to provide the symbiant or the new life will not live very long. However when the symbiant moves into the "fruiting" stage which allows them to create the new symbiants this weakens the host. Essentially the host becomes pregnant, but with the symbiants baby.
As a result life tends to revolve around 1 fruiting individual cared for by a larger group with the group members reproducing with each other then the fruitbearer providing the symbiants.
If this symbiosis evolved early enough in the planet and provides a large enough advantage then you could expect this sort of pattern to be very widespread throughout the animal life.
[Answer]
Interesting question. Here's a thought:
Perhaps very early in this world's evolution, the first RNA could have combined to begin the process, then very early on a third contributor developed. This became the successful combination on this world, and from there all life developed.
As *we* recognize two reproductive sexes, male and female, your world would have three recognizable reproductive sexes; eg. male, female, and perhaps "somale". Where we each contribute half of our chromosomes to produce our progeny, they could contribute one third, or perhaps one contributes half and the other two contribute one quarter each. *Or*, perhaps two contribute half each, with one acting as a "catalyst" of some kind.
The reproductive cycle would be interesting! Would the nuclear family have three parents, be polyandrous, or be very similar to our own but with the "somale" members of society drifting in and out of relationships much more casually? If the latter, would the "somale" gender be less likely to occur? What societal status would the "somale" enjoy if that were the case? Would coitus between the three genders need to be simultaneous or just close in time? If simultaneous, I think the "inseminee" would probably have evolved a second sexual opening very early along the timeline, assuming that semen is even involved.
Or, perhaps, they're "egg-layers", in which case the physiology could be different altogether.
On Earth, plants which reproduce sexually sometimes require two separate genders of plant, but sometimes the plant can reproduce with itself, and sometimes the plants are all unisexual but cannot reproduce with themselves.
It's interesting.
[Answer]
I won't
there is no selective advantage to it and quite a few disadvantages, it is evolutionary unstable and the simple logistical benefit of only needing to find one mate will drastically favor two sex systems. There is also really no way to get it to evolve, since they had to go through a two sex stage from their unisex ancestors.
You stat with un-differentiate gametes, then you get specialization, but you will never get to three specialized gametes from one unspecialized one without going through a two gamete phase, and there is no advantage to go to three from their.
there is a reason it has never evolved on earth despite ample opportunity.
] |
[Question]
[
Imagine if the Moon had its own moon. A moon (likely an asteroid) that lies within the Moon's Hill Sphere. I have read elsewhere about the fate of such a moon. Over time due to the Moon being tidally locked to the Earth, tidal forces would make as such that this small moon of the Moon would see its orbit shrink. This tiny object would potentially cross the Roche Limit and be ripped apart forming a ring or would simply come crashing down on the Moon.
In a scenario I am imagining, his tiny moon could have circled around our satellite for around (or more than) 100 million years before being discovered. Is it possible for this moon to survive more than 100 million years in orbit around our natural satellite before being disintegrated, or a a duration between around 4 billion years to 100 million years, assuming that this object was naturally captured by the Moon sometime in the past?
[Answer]
This is complicated because the main effect producing instability depends on where the satellite's orbit is and how big the satellite is.
Close to the Moon there are two main perturbations: lumps on the Lunar gravity field and tidal friction. Lumps in the Moon's own gravitational field are caused by non-uniform distribution of mass ([Mascons](https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)), mostly) within the Moon. It can have a surprisingly large effect -- close-in artificial satellites need to be tended and their orbits adjusted if they're to remain stable for thousands of orbits. These effects are independent of the mass of the satellite. I'm having difficulty finding papers I can link to, but [here's an abstract of one](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160001688.pdf).
Tidal friction is slower, but very, very certain and will cause larger masses to spiral in.
Higher altitude circular Lunar orbits in general are not stable. For example:
>
> "High-altitude circular orbits around the Moon are unstable," says Todd A. Ely, senior engineer for guidance, navigation, and control at NASA's Jet Propulsion Laboratory. "Put a satellite into a circular lunar orbit above an altitude of about 750 miles (1200 km) and it'll either crash into the lunar surface or it'll be flung away from the Moon altogether in a hyperbolic orbit." Depending on the specific orbit, this can happen fast: within tens of days.
>
>
>
And here's a [link to a great presentation](https://icubesat.files.wordpress.com/2015/05/icubesat-2015_org_b-1-4_lunarorbitstability_dono.pdf) which notes the effects:
Main perturbations:
* Lunar mass concentrations
* Earth/Sun third body effects:
+ Main contribution over 700 km
+ Significant between 400-700 km
+ Small between 100-400 km
+ Almost negligible below 100 km
* Solar radiation pressure
OTOH, some papers have suggested that some elliptical orbits which are far from the plane of the Moon's orbit may be moderately stable.
But it appears that *nothing* can give you stability in the hundreds of years or longer range.
[Answer]
This is a good question. Chances are that the Moon being tidally locked would cause the satellite to eventually deorbit, this would happen faster if the orbit was retrograde but even a prograde orbit would still have it very slowly slow down to deorbiting.
**Roche Limit**
If the satellite was fairly substantial, made of rock, not a collection of dust and ice as some asteroids are then providing it was not too big then it shouldn't break apart. The larger the satellite, the higher the stress that can be exerted upon it by the gravity of two bodies. So a fairly small, maybe 20-40km asteroid should be fine.
*I'm just a space fan, not an astrophysicist, so if I'm wrong on that then anyone please correct me*
**However**
A way to limit its deceleration, and eventually de-orbit, would be to have the satellite in a polar orbit, it would still slow down, but at a much much slower rate, and the tidal locking wouldn't have as much of an effect.
Victorbrine Cassini, I wouldn't accept this as an answer unless you don't get any other answers, Hopefully, someone more qualified would be able to answer your question with some maths.
[Answer]
Your satellite needs to be small, persistent, and evade detection from Earth. High satellites are unstable and might be noticed from earth.
Here is a scheme of mine from the Halfbakery: **the Moon VLO (for Very Low Orbit) device.** The halfbakery is sadly incommunicado these past weeks, so link is via the Wayback Machine.
<http://web.archive.org/web/20171015065017/http://www.halfbakery.com/idea/Moon_20VLO_20Device#1331956156>
>
> Stuff in orbit is always falling down toward the planet, but always
> missing on account of its sideways motion. The closer the orbiter is
> to the planet, the harder it is to miss it as it is falling. But it is
> still possible, provided there is enough sideways motion. I propose
> that a VLO {very low orbit) device be constructed and set into orbit
> around the moon. I choose the moon for its lack of atmosphere, which
> otherwise would slow the VLO and make it crash. The VLO would be set
> into orbit about 2 feet (or 1 meter) off the ground. A path would need
> to be carefully cleared and marked, as a rock in the way would have
> tragic consequences. The device would need to be very shiny, to
> reflect rays which might push it down toward the surface.
>
>
> A railgun might be used to start the VLO. The railgun would need to be
> quickly moved out of the way as the VLO completed its first orbit. The
> VLO would be good for all the usual sort of things very low lunar
> satellites are good for, except it would be better, because it is
> lower.
>
>
> — bungston, Sep 11 2003
>
>
>
from the comments
>
> The thing would be going at about 6000 km/h and complete a circle
> every hour and 50 minutes. It would take a big rail gun...
>
>
> — AO, Sep 11 2003
>
>
>
So too your satellite. No-one has noticed because it is so small. Nonuniform gravity is not important because its path goes thru regions such that there is a uniform pull along the entire course.
If your characters visit the moon and find a funny little path cut through a hill, have them stand off to the side a ways while they do their wondering. They will figure it out within an hour and 50 minutes.
] |
[Question]
[
In a fantasy setting I'm working on for an RPG, I was trying to determine what properties I could use to determine how well metals resist magic and how readily they absorb enchantments based on something measurable in the real world. Then it hit me, conductivity.
**The rule:** More conductive metals would be able to soak up more magic before being saturated, but would also be more vulnerable to magic damage. Less conductive metals would resist magic damage, but could not hold as powerful enchantments.
Going off a world that has the equivalent of ~14th century metallurgy and blacksmithing techniques, which metals would be favorable for magic resistant armor? And which metals would make for the best enchanted weapons and armor?
Keep in mind, they still need to be able to be light enough and durable enough to function as armor and weapons (otherwise I think gold and silver might win in the enchanted category.)
**Clarification:** The conductivity rule is only for metals. I'm going to work out a different measure for non-metals.
[Answer]
This is an interesting question.
All metals conduct reasonably well. Besides, your knights want to look good! They want to feel important! They want silver and gold on their armor, which would be like lightening rods to magic.
But... what if we coat the armor? In an ideal world where all materials were present, if you coated the inside of your armor with rubber (a wonderful insulator), then you'd have armor that could withstand sword and wand alike and sill make the knight feel grand!
On the other hand, if we assume all materials aren't present and we only have access to those materials available in medieval Europe...
* Laquer could be applied to rigid armor, such as plate mail.
* Leather would be an inexpensive and easily available insulating material, but when wet it conducts just fine (salty sweat is not your friend).
* Plant fiber is a reasonable insulator, and it wouldn't be quite so susceptible to sweat. Would wear out quickly, though. as in, *decompose.*
**I've got it!**
Layered satin or silk would probably do the trick. And your knights would look smashing at the same time. Those layers would still become more conductive with sweat, but the trade-off is they'd last longer than plant fiber, wouldn't chaffe like leather, would breath almost like Egyptian cotton, and would look good.
*In fact, you'd look a bit like a [Roman soldier](https://qph.fs.quoracdn.net/main-qimg-991eb15fecfe85416cbc5ad7f8904aa4-c).*
[Answer]
I assume you meant resistivity (which is the property of the material) not resistance (which is the property of the object), since we are comparing different metals.
Since you mentioned that this only applies to metals, I will not consider semiconductors like Silicon and Germanium either. **Nichrome** has a very high resistivity, almost 60 times of that of Copper. Due to its high resistivity, it is also most widely used as heating elements, for instance in electric kettles. Wikipedia tells me that it is usually "80% nickel + 20% chromium". **Unfortunately both were not discovered until the 1700s.**
If you are unwilling to ignore the historicity, then we have to only look at the metals that were known to us in the 14th century, which were not many:
* Arsenic (metalloid): 3×10-7 m Ω
* Antimony: 4×10-7 m Ω
* Tin: 1.1×10-7 m Ω
* Lead: 2.1×10-7 m Ω
* Zinc: 5.9×10-8 m Ω
* Copper: 1.7×10-8 m Ω
* Silver: 1.6×10-8 m Ω
* Gold: 2.2×10-8 m Ω
* Mercury: 9.6×10-7 m Ω
* Iron: 9.7×10-8 m Ω
So the winner seems to be **Mercury** (though it is a liquid in rtp).
The winner that is a solid in rtp is **Antimony**.
(Could not find much information on alloys though.)
[Answer]
## Iron Nickel Alloy
While our pre-modern ancestors did not know how to isolate Nickel from Iron to create these alloys in a controlled manner, Meteorite Steel has been used by man since the early bronze age. Some of these natural alloys contain around 30% Nickel. Iron Nickel alloys in this range typically have an electrical resistance of about 8.15E-7 m Ω giving it a higher resistance than any pure soild at room temperature metals known before the 14th century.
### ... or rusted iron depending on your definition of "metal"
If you allow for metals alloyed with non-metals, you could also consider using rusted iron armor. While rust was normally avoided by the medieval knight, metal oxides typically have electrical resistances that are orders of magnitude higher than pure metals. So if you want to make your breastplate able to stop a magic attack, just leave it outside in the rain for a few weeks. That thin rusty exterior will offer more resistance then the entire remaining width of breast plate.
] |
[Question]
[
In the critically acclaimed horror film, [The Thing](https://www.imdb.com/title/tt0084787/), Blair determines that if the Thing was to reach civilization, it would take over all life on Earth in only 27 000 hours or a bit over three years. Is this number accurate?
First, for who haven't seen the film, a brief summary of The Thing's abilities;
1. The Thing has the ability to absorb and copy the DNA of any life-form it consumes, allowing it to take on its appearance, memories, and mannerisms.
2. Each individual cell of the Thing is both part of a singular multi-cellular lifeform and a distinct, independent entity at the same time. Therefore to kill it, one much kill every cell of the Thing on the planet.
3. It is implied in the first movie [and outright confirmed in the prequel] that the Thing is unable to replicate dead cells; including metal and cloth.
There are of course more rules that can be read [here](http://aliens.wikia.com/wiki/The_Thing), but those are the most basic of rules. Using these as a base, would the Thing be able to take over humanity (that is, make it so that there are no more humans alive of Earth), and if so, would it take the 27 000 hours mentioned in the Film?
[Answer]
A ***really important ability*** that wasn't mentioned in the question is that The Thing replicates as it absorbs. Thus, after absorbing a human, what you have left over are two Things.
So... about 7.6 billion people on earth, all other things being at least temporarily equal, how many eat-the-human cycles must there be to get all of us?
2n-1 = P
Where "P" is the population and "n" is the number of cycles to get there. Since 7.6 billion >>>>>> 1, I'm going to ignore the 1 and say 2n = 7.6 billion or n = 32.83
**So, what's a cycle?**
If everybody is standing in a convenient pyramid shape such that The Thing can go person-to-person in a single second and conversion is instantaneous, then the job's done in 33 seconds. Boom! Instant alien planet.
But, the conversion process isn't instantaneous. I don't have a copy of any of the movies to work with, but let's assume this task takes 3 minutes on average.
Next, how long does it take to move person-to-person? One would assume that in a city this is much simpler than out in the country. But, let's face it, once people see the absorbtion process begin, they're going to run like Macey's having a 90%-off sale. So...
* Assume that in cities a solid 15 minutes is required to get to the next victim.
* Assume in the country that an hour is required to get to the next victim.
In 2014 the UN reported that approximately [54% of humanity lived in urban settings](http://www.un.org/en/development/desa/news/population/world-urbanization-prospects-2014.html). Let's take that at face value.
* 54% of the time we only need 15 minutes. 54% of 32.83 cycles is 17.73.
* 46% of the time we need an hour. 46% of 32.83 cycles is 15.10.
17.73 \* (0.25 hours + 0.05 hours) + 15.10 \* (1 + 0.05) = 21.174 hours.
***Dang! That's fast!***
This suggests it takes a LOT longer to either absorb a human, move to the next human, or both. Let's say it takes 0.5 hours to absorb, then what is the average get-to-the-next-human time?
32.83 \* (X + 0.5) = 27,000
X = 821.92 hours or, basically, two weeks.
The Thing must really like instilling fear in humanity because taking two weeks to get to the next course in the meal is a long honking time.
**Answer: The Thing can take over Earth and most of Alpha Centauri in 27,000 hours**
] |
[Question]
[
>
> The ideal murder weapon is probably an **icicle**, because then you can melt the evidence
>
>
>
Well, it's far from perfect. At least when magic kicks in.
The story is set in this modern world, with elemental magic added in (fire, earth, wind, water). Magic users can manipulate their element (move, change shape, change state) with regard to (not-hard)science.
>
> No manipulating heat for fire user, though.
>
> No manipulating dust for earth user, except if it directly originated from *ground*.
>
>
>
Magic users are rare. They got their power either from their bloodline, or from a spontaneous mutation. The element is inherited. Though there's no successful record of mixing two elements to a child, there are very, very few that can manipulate two elements at once. It is *suspected* that they are very rare spontaneous case, or the result of an experiment.
Magic is widely known, though. Magic users are both feared and respected. They can use magic without any effort and without any drawbacks. However, the society has long stabilized since the Witch Hunt, and most magic users (especially within a household) are responsibly using their power. Among the respectable jobs, some choose to work for the police force as a forensic investigator.
I'm mainly interested in **how a forensic investigation can be conducted with the aid of elemental magic when the murder is done magically?**
For this question, let's use the example in the **icicle murder.** The icicle may or may not be made by a water user, it is not known yet (although it is made by a water user). It is **not important** how to identify the murderer, or whether the murder is magical or not.
I'm thinking of a wind-user that can use wind-magic to gently remove dust, or powder used to identify fingerprints, but it seems very trivial. There's no other kind of magic (like divination, teleportation, or such) except elemental magic.
**Is enhancing forensic investigation by elemental magic plausible? What are examples of the techniques that can be aided by elemental magic?**
**Note:** It is very different from [Magic and the Legal System](https://worldbuilding.stackexchange.com/questions/32598/magic-and-the-legal-system) since it allows divination based magic to help closing the case. Most answers are based on divination school spells, so it's gone very boring reading other answers.
[Answer]
To answer the first question, yes, I believe having a little magic here and there would be useful in an investigation, but its use *would be limited.*
To be honest, it depends on how you look at it. There’s really two sides to a magical CSI, if you think about it. They’ve got their magic, but they’ve also got their brains. Obviously, magic is their key tool, but them having magic might also have some effects on how they perceive a crime scene. With that in mind, you could have two separate approaches. The second, though, is the more notable.
## **1.) Uses of Magic in CSI**
Beyond a few base operations, there aren’t actually that many uses for the type of elemental magic you described. A few of the ones that *do* come to mind, though, include:
**Earth—** Examination and collection of footprints in their original form from dirt/mud, possible ability to analyze dirt/mud found on the crime scene (it’s a real thing—sometimes you can find the region the dirt on Vehicle X’s bumper came from and use that to find out where the vehicle could have been), and excavate makeshift graves left behind by the killer in a whole lot less time than a team of people with shovels could do it.
**Water—** Not really a whole lot; maybe taking or preserving blood samples, or recording or manipulating the humidity of a crime scene to preserve evidence. Additionally, would be good for freezing certain types of evidence (blood, bones, or anything else organic, pretty much)
**Fire—** Aside from burn tests in a lab (which could easily be done without magic) and maybe flame control onsite, not a whole lot of direct users for fire magic, since fire is so destructive and thus a hazard to the crime scene.
**Air—** Probably actually pretty useful when it comes to collecting samples of foreign gasses on site. More mundane stuff might include something like trapping flies off a body in vials with gusts of wind for lab analysis. Very specialized, though, not a whole lot of generalized uses.
## **2.) Uses of Magic-Related Knowledge in CSI**
I think this is the more interesting of the two options. If you assume that a magician with a certain type of elemental magic has studied his or her element to the point that they know it better than most people, then their extra knowledge, while not a direct effect of their magic, could be invaluable. Examples might include a fire elementalist being exceptionally good at arson cases because they know the way fire behaves, allowing them to track down the source of the fire quickly, or an water elementalist who specializes in finding things that criminals have dropped into rivers or oceans because they have a deep understanding of how water flows. I won’t go into too much detail ‘cause it’s not exactly what was asked, but I think the secondary knowledge of the elementalists might be more valuable than their actual abilities when it comes to CSI.
[Answer]
I agree with others that ability to 'interrogate' elements over which one has magical influence would be most beneficial, for example, can water 'remember' being ice?
The Chinese Wu Xing recognises five elements: Earth, Wood, Water, Fire, Metal - they sound far more useful for your purposes.
**EDIT:** I've abandoned the Chinese Elements Idea, although I still think it good
Manipulation of elements by magic must, though, leave some evidential trace - though it may be difficult to find. Even, according to the OP, fire users cannot manipulate heat (I find it a bit difficult to understand that), so implicitly making ice magically does not involve freezing, only a change of state.
So how easily does a magical icicle melt? And does it melt normally? An icicle melting normally would melt from the outside in, as heat transfers from the environment - but a magical change of state does not seem to involve changing temperature, so the melting process is likely to be different - does the magical change of state just collapse?
The difference between a slow change of state, aka ordinary melting, and sudden change, aka, magical collapse, is likely to produce different forensic evidence. No 'sensing' required.
For example: slow melting produces slow leakage of cold water and some absorbtion, since it will tend to be absorbed as it melts, it will not cover a large area. Sudden melting will create a rush of water, possibly at ambient temperature - this will spread over a wider area. If observed by any means, it is likely to be sudden and dramatic.
[Answer]
**Forensic Agents**
They mostly use science to try to understand the marks in the body of a victim, little clues in mostly everything that is around a murder, that could help the detective to find the truth. If there is a common occurrence that people use magic to commit crimes or at least in some part of it. Having an expert in this type of manipulations would help in analyze any "trace" left for it.
Most of the cases an agent had to investigate are really standard. It is uncommon to find what you see in a TV show, about a super intelligent assassins that can do anything without people tracking him.
An example: The detective arrives at the location of a hit and run accident, the forensic agents are collecting evidences and taking pictures of the body, taking measurements, looking for possible clues of the type of car involved in the accident.
Most of the investigation and imagination is done for the detective in charge of the case. The forensic agent mostly is an expert in detection, handling and storage of the physical/digital clues of a case.
] |
[Question]
[
I am writing a small piece of fiction for a game. I wanted to describe it as much as possible. The setting is Earth, more than a milenia after an event of cataclysmic proportions that made the planet almost uninhabitable. The result is a planet mostly toxic, in which people need some sort of breathing apparatus to survive(am still going to work on that) and with something as close as to 20-40% of all its surface water. Would be that believable? Or for most people it would seem like a impossible condition for sustaining life, even on a ridiculous small amount? Also, if possible what would be the smaller percentage that I could use and still keep it believable? I really want to me it a hell on Earth.
Most of the water was evaporated into space, part of it went underground due to a massive damage to the planet's crust and a tiny amount is still trapped in the most higher mountains and in the poles as ice and snow. Big animals like elephants, and whales doesn't exist anymore, most of the creatures wandering Earth now are less dense and some have way more volume and less density, some even like balloons of gas. The underground, in other way, and in old places covered from the sun and from the dry there is a lot of moisture and it helps the overgrowth of fungus.
It's important to note that the creatures in this setting aren't realistic, and as knowledge of how they came to Earth is unknown for the survivors, this topic is rarely raised. Most of them are highly toxic and poisonous to humans like nothing on the old Earth.
The world is most likely a big desert. Much like mars. But on the deepest locations of the old oceans is where there is still water and a green forest circles it all. The idea goes like this: [imgur](https://i.stack.imgur.com/JeIfp.jpg).
I don't need equations and such things. I don't really want it to be hard fiction. I just don't want people thinking that it is all wrong at the first moment they read it.
Thanks, and sorry for the English, I'm Brazilian and I'm still working on making English my second language.
[Answer]
Before I answer your question, welcome to World Building. This community is related to Science Fiction in many ways, but here we answer and discuss questions related to building an environment according to your requirements.
Your world focuses on an alternate Earth, where Earth has gone through some major changes from what it is now in real world. In particular, you ask:
**1- ... with something as close as to 20-40% of all its surface water. Would be that believable?**
If that is believable or not, depends on the type and severity of the disaster which fell upon Earth. If the type of disaster is correct, then it will definitely be believable.
For example, if Earth was hit by a series of extremely large (~15 km diameter) asteroids, that would release immense amount of heat, equal to millions of atomic bomb explosions. The temperature required to break up water into hydrogen and oxygen is about 2000 °C. In case of a mega disaster, a large amount of Earth's water will decompose into hydrogen and oxygen. Hydrogen will rise up in the atmosphere and will slowly be lost into space (hydrogen often escapes into space due to solar wind, from the atmosphere of low gravity planets like Earth). This will leave behind an Earth which is completely different from the Earth we know. A lot of water would be lost, but the atmosphere would be **extremely** rich in oxygen. I have not done any calculations about it, but my crude guess is that 90% of the atmosphere (by mass) would be oxygen. Also remember, that a disaster of this scale will wipe out ***everything*** other than extremophile bacteria. There will be nothing larger than amoeba left alive in the oceans or on the land. The climate would undergo extreme changes and the whole planet will probably undergo an ice age for tens of millions of years. Only the people up in the satellites would survive such a disaster. All the others (even the last man on Earth) would die within one year after the first 15 km asteroid falls.
Another, less damaging method of removing surface water could be by some sort of new bacteria. The bacteria breaks down water into oxygen and hydrogen, and then uses hydrogen in respiration. This bacteria thrives in the oceans and rivers/lakes and begins to decompose water into hydrogen and oxygen in large quantities. Scientists program a virus to kill that bacteria only. After many decades, all the bacteria of that kind are killed, but they have already decomposed 60% of Earth's water. This will again leave a planet very very different than what it is today. Almost all of the humans and other creatures will die. The only humans surviving the global change will be living deep in shelters with artificial environment.
So yes. If you plan your disaster nicely, it will be believable. Heck! If movies like Looper and Matrix can be believable, your idea will be believed too.
**2- Or for most people it would seem like a impossible condition for sustaining life, even on a ridiculous small amount?**
Yes, most of the humans with our current body structure will die. Very few can survive, but they will be living under hellish conditions. Seasons will be extremely severe and wind storms will be far more powerful than anything we know today. Usually the wind and dust storms will blow over areas as large as whole continents.
**3- Also, if possible what would be the smaller percentage that I could use and still keep it believable?**
You could go on and remove all the water from your world if you want. Most of the things in science fiction are not possible under current scientific knowledge, that is why it is *fiction*.
Just keep in mind that all life forms on our planet require water for survival. If people and animals don't get drinkable water, they die. If plants don't get enough water in the soil, they die. If plants die, animals die because there are no plants to eat. If there is no rain (due to too less surface water), many bad things will happen to the large scale climate and a lot of plants and animals will go extinct. If you only want to keep a few people in far off places to survive in artificial conditions, you could go on and remove 85% of all water on the planet. Earth will become hellish and most animals will die. Most of the plants will die too. The surviving people will need to have their facilities located near the small seas and convert seawater into freshwater to survive. They will have to keep fish and cattle in small areas and grow crops too. It will be possible with advanced technology, but it will only support small groups of people, located far away from one another, near seas and rivers.
[Answer]
**Even at 20% water surface, your planet is more believable, hydrologically than Arrakis. Go for it!**
I'm no climatologist, but even with 20% surface water, you'd be in a more realistic range than Frank Herbert's famous (and Hugo winning) desert planet Dune, or more formally <https://en.wikipedia.org/wiki/Arrakis>
Suggest you read that (if for good notions on arid-planet survival tech) and for some amazing world building.
Surface water in the warmest areas will contribute more to your planet's water cycle. I'll presume that your planet has enough of a water cycle to have something like Hadley cells; that might help you rough out your large-scale climate regions:
<https://en.wikipedia.org/wiki/Hadley_cell>
I suspect you'll want an equatorial ocean or several significant equatorial seas. Is the ground water close enough to the surface to extract and use? If so, competition for still-farmable places is a great plot element.
] |
[Question]
[
Imagine the following situation: There is a global catastrophe that will destroy the earth and there is a habitable planet in reach for spaceships. But it is technically possible to bring only 50,000 people to that planet who have to found a new society there.
What would theoretically be the ideal composition of these 50,000 people concerning sex, age, education, profession etc.? Are there any studies or statistics concerning this topic (ideal composition of a society, not inhabiting new planets)?
[Answer]
A smaller society can be managed much better, without the need of full blown government, economy and the like. I believe occupations would be around like this: miners (1k), botanists (250), farmers (2k), medical doctors/ER personnel (1k), civil engineers (100), electrical engineers/technicians (1k), computer programmers/technicians (100), mechanical engineers/mechanics (1k), builders (1k), teachers (2k), factory workers (5k), caretakers (1k), cooks (500), law enforcement (1k), scientists of various fields (2k), entertainers (artists, musicians, etc) (250), managers (2k), children from all age groups (~30k). These numbers tilted a bit to ensure sufficient food production despite the alien world. Additionally, there should be enough builders to create a town in the middle of an alien planet.
All occupations should be at their ideal age. A very young engineer may not have the capability of an experienced one. Gender distribution should be 50%. All people on board should be sufficiently educated. But most importantly, everyone on board should be free of genetic defects and should be tested psychologically. You would ideally want people that will be able to cope with a task like this.
[Answer]
This is really a philosophical question. What kinds of people form the seed of the society you want to live in?
Everyone will choose a different mix, everyone will feel there's is the best choice but there's probably no way to objectively compare two different answers without obvious flaws.
The outcome does not depend solely on the choice of people. Other important considerations are the equipment, technology and supplies you get to bring, as well as the conditions on the ground at the destination. I'm going to assume we can bring high technology and basically any equipment we wish and that the destination is largely earth-like (because anything else makes the people question pretty irrelevant)
I'm concerned with preservation of knowledge, science and technology. I'd try to bring every shred of knowledge ever generated in duplicate form, samples of all recorded genetic diversity. Redundant expertise with every field of science and technology. And a core of thinkers and artists that represent the best humanity has to offer.
I'd bring renowned professors in as many important fields as possible and use the transit time to spread the knowledge around more widely. Consider NASA's practice of choosing highly skilled astronauts with multiple advanced degrees.
I'd do loose screens of genetic and mental health (try not to tyrants about it, because nobody wants to live in a society like that)
Some additional important questions which will affect your outcomes:
How long does the trip take? What's the command structure on the ship? What's the proposed social structure at the destination?
] |
[Question]
[
[Bioluminescence is badass.](https://en.wikipedia.org/wiki/Bioluminescence) It involves living beings emitting bright light in the visible spectrum.
Would it be, though, possible that a lifeform emits UV (ultraviolet) light? Does it occur in reality, maybe?
What are the requirements for it to happen?
[Answer]
With regards to the real-world, [the NOAA says that some deep-sea crabs have low-level UV sensitivity in certain pigments](http://oceanexplorer.noaa.gov/explorations/09bioluminescence/background/plan/plan.html). This would seem to indicate that creatures there may emit UV light - which is exactly what you're looking for - potentially as a form of communication1:
>
> In addition, data obtained on previous OE-funded expeditions indicate that the deep-sea benthos may produce novel, short wavelength bioluminescence. During Deep Scope 2005, we discovered that several species of the deep-sea crabs (figure 2b) have an ultraviolet (UV)-sensitive visual pigment in addition to a blue-sensitive one. In their dim light environment, sacrificing room in their eyes for a UV visual pigment suggests that UV sensitivity plays an important role in their ecology. Just as unusual UV sensitivity in several deep-sea pelagic species has been linked to bioluminescence, we suspect that UV sensitivity may also function to see as-yet-undiscovered short wavelength bioluminescence from benthic organisms. UV bioluminescence in the benthos may be a novel private channel of communication, allowing these animals to find their preferred habitat.
>
>
>
Additionally, [*Photophysiology: Action of Light on Animals and Microorganisms; Photobiochemical Mechanisms; Bioluminescence*](https://books.google.com/books?id=k67SBAAAQBAJ&dq=luciferins+emitting+UV+light&source=gbs_navlinks_s) cites the findings of Cormier and Eckroade (1962) of evidence of bioluminescent emission in the UV wavelengths in three species of the *Renilla* genus (commonly called [sea pansies](https://en.wikipedia.org/wiki/Sea_pansy); these effects were later investigated by [Hart et al. (1979)](http://pubs.acs.org/doi/abs/10.1021/bi00578a011?journalCode=bichaw)). It's important to note that the emission of photons in UV wavelengths is only due to a "tailing off" of the spectral energy distribution in the bioluminescence of these species.
Feasibility is more complicated. [The mechanism2 is](https://en.wikipedia.org/wiki/Bioluminescence#Chemical_mechanism)
$$\text{L}+\text{O}\_2+\text{ATP}\to\text{oxy-L}+\text{CO}\_2+\text{AMP}+\text{PP}+\text{light}$$
as mediated by the enzyme [luciferase](https://en.wikipedia.org/wiki/Luciferase) using one of the [luciferin pigments](https://en.wikipedia.org/wiki/Luciferin). Essentially, the luciferin changes from an excited state to a ground state. Now, we can postulate the existence of a luciferin with an energy difference between these two states exactly right to produce one or more UV photons; in fact, [*Biology: The Unity and Diversity of Life*](https://books.google.com/books?id=7W3OlS7QUMoC&pg=PA102&lpg=PA102&dq=luciferins+emitting+UV+light&source=bl&ots=ZnLnXcfN3-&sig=eW2O7MnH_dReSvZqJ2JtjLeJwUI&hl=en&sa=X&ved=0ahUKEwjg8O_boM7NAhVLpx4KHag0BDkQ6AEITjAH#v=onepage&q=luciferins%20emitting%20UV%20light&f=false) claims that "some even emit ultraviolet or infrared light" but doesn't specify which luciferins it is referencing.
---
1 UV light is used for communication in other animals; see [*Sensory Ecology, Behavior, and Evolution*](https://books.google.com/books?id=_jBkszEITMYC&pg=PT227&lpg=PT227&dq=ultraviolet+bioluminescence&source=bl&ots=of223SNe85&sig=zJdNvjK4I0c01uMdsayGaqkG4iQ&hl=en&sa=X&ved=0ahUKEwiO8oPn39DNAhXL2B4KHQM2D5A4HhDoAQg-MAY#v=onepage&q=ultraviolet%20bioluminescence&f=false).
2 Note that this is not the only reaction mechanism for bioluminescence.
] |
[Question]
[
I am trying to build a world which has a bit larger gravity force than earth, 1.25g. And I was wondering which impact could this have on its geology and life evolution.
I think that with a higher gravity two things would be true:
* No flying species, because it would be harder to lift of the ground.
* No big mountain ranges. Maybe the higher altitude of a mountain would be around 3000 meters.
Maybe most animals would be relatively short but very robust, so they can support the weight. Compared to earth life form they would be slower but much stronger.
What do you think?
Asumptions:
* The Atmosphere composition is similar to Earth
* The Star is similar to Sun
* The Planet has a moon big enougth to keep its axis stable
* The Planet is a bit closer to its star, so its hotter, but not too much (0,9 AU)
[Answer]
There will be significant differences between the earth and your planet.
25% of additional gravity means 25% additional mass, but only about 10% additional radius. Thus, the atmosphere will be denser and there will be more water on the planet. I don't have a planet simulator ready to decide whether your planet (closer to the sun) will come out as a hot Earth of a cooler Venus, let's assume a hot Earth.
**Sea level** will be higher (just because there is more water available, but the surface has not grown proportionally). Your planet will consist of chains of islands (representing the hills and mountains). The land/sea ratio will be much smaller than on Earth. There will be lots of heavy tropical storms.
The will be **no ice caps** at the poles.
Land bound life forms will be less sophisticated than on Earth (no stable continents, but only rather short-lived islands support them) and probably be able to cross the water (either swimming or flying). Maybe you have some kind of air-breathing flying fish filling the evolutionary niche of birds.
There are 25% more radioactive elements inside the planet, but the surface has not grown proportionally: The geological activity of the planet is probably higher than on Earth.
I agree with the other posters that increasing the amount of gravity will not have significant influence on biomechanics, all kind of body shapes that work on Earth will also work on your planet. When there are kind of reef-building corals, your planet will have lots of atolls.
[Answer]
I don't think that 25% of our gravity make such a big difference.
There still probably would be birds and other flying creatures, although with stronger wings.
There still would be mountain ranges, and even ones that exceed the heights of Terran mountains would surely exist - geological forces operate very slowly and are very powerful, which means that changes in gravity usually don't really affect the structure of the planet.
However, your atmosphere may be a little bit more dense, which could strengthen erosion.
[Answer]
I don't think you'd see a significant change in shapes overall - you'd still have spindly-legged mouse and thick-legged elephant analogues, but they'd both be smaller than their Terran counterparts.
Flight should still be possible - higher gravity means a denser atmosphere, which should balance out the gravity.
There would be some slight differences if you placed them next to Earth life, but I think you can assume the same evolutionary pressures would occur as on any other Earthlike alien world.
[Answer]
Well mountain ranges would likely be smaller, but not that much smaller. There certainly wouldn't be anything as tall as Everest. On Earth, the current max is around 10Km, increasing gravity to 1.25 I would make a rough guess of about 8km. You can [play with the formulas here](http://www.hk-phy.org/articles/mount_high/mount_high_e.html) if you want a more accurate number.
As far as flying animals. That change is certainly not enough to stop flying animals. It might reduce the numbers of species that fly however. One of the things that might help balance out the gravity pulling down, is a stronger gravity could help increase the air density, allowing for easier lift. I would guess more species would be gliders, like the albatross or vulture.
As far as everything else, it would be very similar to what we have available, with sizes being slightly shorter and and squatter. Skeletal systems will need to be stronger and denser to handle the extra stresses. And of course muscle systems will need to be stronger.
Gravity also plays a roll in how tall trees can grow, because of [capillary action](http://web.mit.edu/nnf/education/wettability/gravity.html) and how high it can move water up the trunk.
But overall, a %.25 increase in gravity wouldn't be terribly different to what we have now.
] |
[Question]
[
Listen.
You hear that crunching, cracking noise? That's the marrow adders. They're all around us. Tiny, timid, pretty much harmless. If you break open one of the larger bones left behind by the [bonegrass](https://worldbuilding.stackexchange.com/questions/38354/how-often-must-carnivorous-grassland-eat) you'll probably find a marrow adder peeking out at you like you've done something wrong.
What? You don't believe me? Well, I'm telling you that crackling noise ain't the campfire.
---
Marrow adders are tiny, inoffensive, nocturnal snakes. They measure 15cm (at most) from nose to tail when adult, and with heads that barely graze 5mm wide. Their primary food (as you might guess from the name) is bone marrow, which they suck out of the skeletons of creatures unfortunate enough to die in the bonegrass fields, after they've been stripped by numerous other scavengers. They also like to use the bones to hide in, as they're camouflaged and patterned to match bone. More than that, they like to hide inside larger bones, both as protection from the daylight and a good place to hide from any predators.
The question is whether such a small snake would be able to crack, break or corrode it's way into a bone in such a way that it doesn't end up expending more energy than it can hope to get from the marrow inside, and can still get protection from the hard bone itself.
[Answer]
One problem with this theory is that large predators tend to crack the bones open for the marrow inside anyway. However lets say there is a supply of food available.
It seems your snakes are actually already a good shape for this, being long and thin. You would probably better off making them more like worms than snakes at all, so that they can squeeze through tiny holes.
This would then allow them to search the bones for existing flaws in order to access the food inside. If that fails a specially adapted mouth would allow them to drill their way through the bone to get to the marrow.
You should look at marine worms. In particular as was said in the comments [Osedax](https://en.wikipedia.org/wiki/Osedax). They use acid to eat through the bone and then send roots inside to consume the nutrients. Your snakes could do the same or could actually move in through the hole they make. Either would work fine although being outside the bone would leave them vulnerable to predators.
[Answer]
Imagine this [cute little fella](https://en.wikipedia.org/wiki/Barbados_threadsnake) gnawing on your finger:
[](https://i.stack.imgur.com/fceEn.jpg)
*In best puppy talk voice:* "Who's a cute wittle snake? You are!"
*returns to normal voice* " ...Wait... What? He does what?? He's trying to do what to my finger!?!?!? Ohmygodohmygodohmygod"
I would point out that the bone marrow probably wouldn't be the only thing marrow adders would eat. A bone would be a great hiding spot to snatch up larvae, worms, or the huge numbers of insects that would surely thrive in a [field of dead bodies](http://science.howstuffworks.com/forensic-entomology1.htm).
But bone marrow is nutritious enough that it is the [Lammergeier's main food source](https://quantumbiologist.wordpress.com/2010/11/26/the-bone-eaters/). It should be a plausible food source for mama marrow adder and her young, so how do we get her in? The Osedax burrows into bone with acid secretions, and the Lammergeier has a highly acidic stomach to deal with the bone shards it eats, so acid seems like a good candidate. Maybe mamma adder can also regurgitate some [collagenase](https://en.wikipedia.org/wiki/Collagenase) to speed the decomposition of the hard bone exterior. She can still have a sharp burrowing beak to scrape the softer dissolved bone away. Knowing what vinegar does to chicken bones overnight, I think it is entirely plausible that she could burrow her way into a bone with stronger stomach acids and enzymes in a reasonable amount of time.
[Answer]
If the snakes are really tiny and the bones are from large creatures such as sheep or dogs, then they can squeeze into them by using the holes for arteries & veins. [Wikipedia article on nutrient foramen](https://en.wikipedia.org/wiki/Nutrient_canal)
If the snakes are a bit bigger, then gnawing or digesting bone is well worth it: bones are calcium phosphate. Phosphorus is a vital ingredient in biology - the snakes won't just be make their own skeletons out of it, they'll also be making their nervous system (lots of phospho-lipids), fueling their cellular metabolism with it [ATP](https://en.wikipedia.org/wiki/Adenosine_triphosphate), constructing DNA with it (phosphate group), packing it into their egg yolks to make their babies, and so on. That's why farmers put phosphate fertilizers on their fields - the growth of living things is often limited by the amount of phosphate available to them.
So a fresh bone, packed with fat (bone marrow) and phosphate is a real prize. There will be little snakey punch ups over who gets to claim it. Mama snakes will be all over it like a rash, since it will supply both the lipid and the phospho bits of the phospho-lipids her babies will build their brains and nerves from.
Even a dry bone can be a prize for its mineral content. It will be the snake equivalent of a 'salt lick'.
] |
[Question]
[
*As a variation to my previous question about the domestication of microbes*
So my question is : which animals lend themselves to domestication?
[Answer]
There are several criteria which decide how useful animals are as domesticated lifestock. When you pick your lifestock, you first need to consider which animals are actually useful to you. A useful animal is one which provides you with one of these:
* **Food:** Many animals are solely bred for their meat (like pigs) or their milk (like cows) or their eggs (like chicken). But even with animals which are primarily work animals it can be useful when you can eat them in case of a famine. By the way, when you *only* want to eat them, consider if it might be more effective to let them feed themselves in the wild and hunt them when you need food.
* **Textiles:** Animals which produce a lot of hair are useful because you can shear them in regular intervals and turn their hair into clothes, blankets, bags, tents, ropes and many other useful items. Spinning wool to thread and then weaving or knitting it into textiles is very time-consuming, though (especially when you don't have access to the right tools. A spinning wheel and draw loom help a lot). You can also obtain leather and fur when you kill the animal and skin it. But if you want an animal *only* for this purpose, then domestication has little advantage over hunting.
* **Work:** Providing you with food and clothing might be nice, but it is even nicer when your animal can do more than that. For example, transport cargo, carry you on its back, help you hunting, defend you and your property, pull your plow, eradicate pests or manage less intelligent lifestock. In order to be trainable, an animal must be intelligent enough to learn new skills and understand your instructions, but also obedient enough to listen to your commands. Domestic animals which fall into this category are horses and dogs.
Preferably you want an animal which ticks many of these boxes. One of the best multi-purpose domestic animals is the camel. You can shear it, you can ride it, you can milk it and you can eat it. But specialized animals can also be worth it. Pigs, for example, have no use for us except their meat, but are still worth it because no other domestic animal gains weight so effectively.
But then you also need to consider if you actually *can* domesticate them. In order to be domesticable, an animal must fulfill certain criteria:
* **Diet:** Food is always a scarce resource and you definitely don't want to breed anything which competes with you for it. So you want animals which eat something which exists plenty in your environment but which is worthless as a food source for *you*. Like grass, for example. Carnivores generally make bad lifestock, unless they eat animals you can't or don't want to eat (like cats do).
* **Resilience:** A dead animal is a useless animal, so you want animals which are robust. They should not be susceptible to disease and too hot or too cold weather, be stress-resistant and not be too picky about food quality.
* **Danger level:** You don't want any lifestock which can kill you. So when an animal is stronger than you, venomous and has sharp claws and teeth, that's bad. If it also happens to be aggressive, then you should really look for something else to domesticate.
* **Ability to escape:** You need to confine your animals somehow. Anything which can easily escape from their pen won't stay your lifestock for long. So you don't want animals which can jump, climb, fly (unless you can clip their wings) or dig very well. Unless, of course, their natural behavior will prevent them from escaping, which leads us to...
* **Motivation to escape**: There are animals which are loners and do not like living in groups. This makes them very hard to confine. What you want are herd animals which have a high level of loyalty to their herd. A whole herd is easier to control, because you just have to control the alpha animal and all others will follow. Some species might even accept you as their alpha animal and will then not even try to escape.
* **Breeding behavior:** Some animals have very strange and elaborate mating practices which are hard to accommodate in confinement. Those species which are very picky regarding their mates or require very specific circumstances to get into the mood do not make good lifestock. Preferably you want animals where you just put male and female into a pen and they immediately get it on. A short gestation period and a large number of offsprings makes it easy for you to improve your lifestock in both quantity and quality (through selective breeding).
[Answer]
**No.**
Domestication generally relies on taking an animal which already displays useful social characteristics and slightly modifying those characteristics to make the animal useful for humans. Dogs, horses, and sheep are all naturally group-dwelling social animals who take care of their young and form social bonds with one another.
No animals even close to the size of your humanoids have that sort of social behavior. Most of them are parasitic arthropods.
[Answer]
It's also important to consider that domestication isn't so much an intentional process as it is humans and animals slowly coming to rely on another due to frequent interaction. So most of the domesticated animals on earth were domesticated because they did not avoid humans- usually because they ate food scraps that humans left, and they were useful in some way, so humans let them. For example, cuy, or guinea pigs, were domesticated in Peru because they fed on food scraps near people's houses, and humans let them because they're good for food in times of food stress, and they became important ritualistically in traditional medicine.
] |
[Question]
[
Making a world where you live in the air, as the surface is not survivable (Venus-like) but there are mountains which serve as islands. I'm gonna leave out the story of the planet as it's not important.
So basically I'm looking for believable conditions on the planet (things like dense, layered atmospheres, different atmospheric pressure or magnetic fields) and technologies that will allow steampunk-style airships to exist and be functional without having gas bags the size of zeppelins or using constant jet engines pointing down to stay in the air.
Something like this: (I do realise the faults in the design of the ships in this image, mainly the gas tanks being on the bottom, but I'm just using it as a vague example of the style i'm looking for. Coated in metal with relatively small gas tanks/bags compared to the ship's weight and size, although even smaller tanks would be better. So with the proper design, could it exist?)
How dense can the atmosphere get, but still stay breathable by humans and how much better would buoyant gas perform in said atmosphere?
[Answer]
If the atmosphere of the planet is sufficiently dense, then it would be possible to have relatively small amounts of buoyant gas support much larger structures while also explaining why the surface is inhospitable (just remember, higher pressures begin to blur the line between atmosphere and ocean).
Another possibility for a Venus-like planet is surface volcanoes or geysers that give off enough heat to create constant thermals for the airships to float in. This would only work if they stayed in the same place, however.
More speculatively, a Mercury-like planet could have ships that hover over the terminator and use the heat differential to generate lift (not sure how the exact mechanism would work...).
Finally, instead of having gas-filled bags, you could use spheres with most of the atmosphere sucked out of them as a weight negator. Since a vacuum is, by definition, the lightest "substance" that can exist, this would be much more space-efficient than helium or hydrogen. Unfortunately, this would require some pretty implausible engineering, but the civilization you describe does seem to have interplanetary travel so it isn't out of the question. It also would be less effective on a planet with a dense atmosphere, due to increased pressure.
[Answer]
A Venus like world with a very dense atmosphere will provide opportunities for creating lift with far smaller airfoils than is possible here on Earth. To demonstrate the point, look at the differential in size between the wings of a large airliner weighing 200 tons and the size of the hydrofoils of a similarly massed patrol boat. Since water is @ 800X denser than air at sea level, the hydrofoils are much smaller than the wings of the airliner.
[](https://i.stack.imgur.com/urOCw.jpg)
At the very simplest, you could have gliders with relatively small wings which seek out thermals to gain altitude and then glide off to the next "hotspot". A powered airship would have a propeller or jet engines to provide enough power to maintain airspeed and altitude over prolonged distances. Remarkably, the aircraft will look somewhat like a penguin in proportions.
For a much more steampunkish look, remember that many early theorists and SF writers in the real steampunk age envisioned airships to be exactly that: ships with helicopter type rotors to lift them in the air and allow for flight and flight manoeuvres.
[](https://i.stack.imgur.com/XZ7yj.gif)
The downside of such a ship is the mechanical complexity of the drive system and the rather insane amount of energy needed to turn all the rotors. Given the high density of the atmosphere, the rotors can be relatively small in diameter (as suggested in the illustration), rather than quite large in proportion as modern helicopters are on Earth. Even tilt rotor aircraft like the V-22 demonstrate this, the rotors are so much larger than the propellors on a similarly sized aircraft simply to allow for efficient vertical flight (earlier ideas like the Canadair CL-84 "Dynavert" had issues because using ordinary sized propellers was wildly inefficient in vertical flight)
[](https://i.stack.imgur.com/QVFrq.jpg)
Of course the CL-84 might represent the evolution of a "Dieselpunk" aircraft in your universe; the relatively small wings and propellers will be far less disadvantageous in a dense atmosphere.
[Answer]
Anti-gravity. Creating anti-gravity materials is not within known science but I don't think that's what you are going for anyway.
Just have the alchemists on your world create a metal that falls upwards. It would have normal momentum but negative gravitational mass. The top half of the airships are plated with that metal and the bottom half with normal metal.
The result is self-stabilizing neutral buoyancy in air.
We have no way to create negative mass at the moment but so far as science can tell at the moment there is no reason it cannot exist so have fun with it. :)
[Answer]
A WW2 style ship could not, realistically, function as an airship, even if the atmospheric conditions, or nannites in the air, of magic could make it float.
The reason for this is because that ship was meant to *float on water* and propel itself using its screws.
It has no mechanism to allow it to steer up/down, to change altitudes, etc.
You have to define the parameters of your universe in such a way as to determine exactly what is allowing these ships to float, and then modify the design of a WW2 ship such that it can take advantage of those conditions to A) move and B) change directions as an airship/plane would.
[Answer]
If you are seeking a way to plausibly lift an airship in a high density atmosphere, you may want to consider the use of a cylinder or a series of spheres containing vacuum. Since the science says that vacuum has more lifting power in an atmosphere than hydrogen or helium, the main problem is how to maintain the vacuum in the container against the pressure around it. Another problem would be the weight of the container as it lowers the lifting capacity of the vessel.
One solution was proposed by creating tanks in the shape of a sphere or a cylinder with walls made of two thin layers with a honeycomb between them for strength. I propose the use of doped carbon nano-tubes linking a version of C-60 buckyballs for the inner and outer layers while the use of carbon nano-rods would provide rigidity against the pressure while being light enough to use practically. The use of vacuum pumps to regulate buoyancy would solve the issue of altitude and could maintain said buoyancy indefinitely. Fabrication would be the only problem that would need a solution and there are papers that would supply the answers.
[Answer]
For a bouyant craft as you describe, you need the atmosphere to be the density of a liquid. Consider a [supercritical fluid](https://en.wikipedia.org/wiki/Supercritical_fluid#Properties), which has figured into a couple of my answers in the past. You'll see from the linked article that this can be 100 to 1000 times denser than gas, and maybe 10% of the density of a normal liquid or as dense as liquid. A gas-filled lifter will be within an order of magnitude of the size of the “displacement” of the ocean ships of Earth.
The other idea would be if your world had a super-intense magnetic field, and your ships contained superconductors.
[Answer]
Electromagnetic motor, like *[Tank Farm Dynamo](http://www.davidbrin.com/tankfarm.htm)*, pump electric charge into the Earth's magnetic field to create repulsive acceleration. The only problem being that the amount of power you'd need for flying a battleship at atmospheric altitudes is *insane*, the main reason that the *Tank Farm* example works is that the drag and gravitational pull are minimal and the farm's power is free and abundant. I'm not even sure that it would work in an atmosphere without grounding out and killing everything anywhere near the engine but it's an idea for you to look at in more detail if it interests you.
[Answer]
## You pretty much got it with the zeppelin and blimp idea on Venus.
A way you could get away with it using modern science is by making the atmosphere more dense. That way you could use less volume to get more buoyancy. You would still want to use helium because it's non-combustible and you still want excess volume so you can heat and cool the gas giving you that 3rd axis of movement, (like a hot air balloon but more structurally stable).
## You could still use hydrogen and vacuumed Buoyancy but they come with their own engineering problems.
Hydrogen is a combustible gas which means if your using airships for war you have to make sure they can't ignite your lifting gas or else your ship dies.
With a vacuumed Buoyancy you have to make sure your vacuum is airtight all the time or else you get the same fate as hydrogen.
Really cool idea I want to try out to, seems like it would be a really cool science fiction setting instead of the stereotypical land and water planet.
[Answer]
Or, you could imagine a gas that had much more lift than traditional Helium or Hydrogen.
] |
[Question]
[
The year is 2020, and an organization known as Helios successfully settles a colony of 200 people on the moon.
The colony is self sustaining and is mainly a research center, with most of its residents scientist, engineers, and doctors. The Helios organization is not willing to share any information on its research or the technology used to settle the colony. Helios has no ties to any to nation. Though its members come from all over, they too have no ties.
The rest of the world does not have the same spaceflight technology as Helios and still uses today's current methods to achieve spaceflight.
[Answer]
There is currently a UN treaty on the books relating directly to this, link here: <http://www.unoosa.org/pdf/publications/ST_SPACE_061Rev01E.pdf>
The treaty ruled that all of outer space is technically the 'common heritage' of humanity and as such no nation could formally lay claim to any territory on asteroids or planets. Think like international waters but space. As such, there wouldn't be any fervor over our dear friends Helios setting up a space colony at first.
The problems would probably come from how secretly they're behaving. Everyone would most likely be calling for Helios to at least give a hint of what they're doing.
[Answer]
There would be a lot of responses, most of them being negative.
Fear and a military response. Not only does this organization have technology which seems far in advance of current and near term military capabilities (i.e. launch heavy payloads to the moon, Closed Life Support Systems), but these capabilities can potentially be used against Earth. A powerful system to launch and move heavy objects in space can also move heavy objects on intersection orbits with the Earth. Closed Life Support Systems (CLSS) could potentially be used to create submarines or invulnerable refuges on Earth to ride out some sort of chemical or biological attack against everyone else. As well, since we don't know what they are researching on the Moon, the paranoia factor will go through the roof.
Military forces will be dispatched to seize launch sites, factories involved in making the launchers and space hardware and anything else associated with the corporation. SoF teams will fan across the globe to track down and capture scientists and technical staff who had involvement, as well as the principles and financial backers of the company.
Legal response. An army of lawyers will work to identify and seize assets of the company, the principles, financial backers, corporations which are or are suspected of collaborating with the corporation and so on. While it is not clear that Helios is laying claim to the Moon, they have established "squatters rights" (especially since no one is going to be able to evict them in the short term), so they have started the effective process of claiming the Moon.
Lawyers may also be put on the case to investigate the 200 personnel, who, despite your assertion, still have ties to Earth. If they have real property, family ties etc. they will be heavily investigated to establish if any tax or other financial shenanigans are going on. The personnel may be prosecuted on the basis of tax law, since although they are not resident in their nation of origin, the Moon has no reciprocal tax treaties with the nations of Earth. Citizens of American origin will face tax claims regardless, due to US tax law.
Finally, there will be a space response. No one likes feeling threatened by what is seen as Dr Evil's Lunar lair, so the various space going powers of Earth will plan a response to go to the Moon and seize the base; either cooperatively or individually. Given the response that the corporation has raised, an individual nation going alone against the Lunar colony will evoke a similar response from the other nations of Earth. (This is problematic, since essentially the only nation which is truly capable of mounting a short term response would be the United States, and even then that involves impressing SpaceX, Blue Origin and the big Aerospace corporations into making boosters and space warships to do the job. While a SpaceX Dragon mounting a mini gun on the nose would be cool as all get out, it would be looked at as a threat to orbiting satellites from other nations.
So Helios should radically consider how they are going to set up on the Moon, and how they will prepare the ground for the event.
[Answer]
Heyho,
if you happen to be able to read german language, have a look into Frank Schätzings book "Limit"... I don't know if there is an english translation. Anyway, its about a company that's basically the only installation on earth that is able to yield He-3 from moons surface, but they didn't loose all ties, because they made their head start by building a space elevator (which happens to be located at a us-owned island if I recall right). And... well, its a long time since I red that book.
Anyway, please keep in mind that your moon-base will have a hard time being self sustaining. And at all you might need to do to put pressure at them is taking care of their earth-side operations. Just claim they do produce nasty weapons for groups that want the world see burn and install military at all their earth-bound installations.
Now your group of 300 is just a bunch of people sitting at the dark site of the moon. All they can do is playing space-chess with the 3rd-reich guys who happen to be their since the end of world war 2 ;) Well, in this case they would be the owners of that place, because they where there before any UN-resolutions regarding the ownership of space came in place :P
Okay, back to serious answering: Consider your renegade-scientists as a prime target for any nation with a considerable big budget for military. Sending a intelligent bomb (don't thing about the explosive agent... all it need to do is make a breach in their base' hull) up their if China, Russia or the USA (europe may have fallen apart until this date) get annoyed is something that any Kerbal Space Program Computer Player could accoomplish if he get the resurces... You could use an old soyus-capsule for accidential crahsing that building. Or laser them. Use them for railgun practice. Today technology isn't far from being able to reach targets this far.
And as said before: while its kind of save on the moon, they can't do much up their if their earth-bound facilities are hold by un-peacekeepers (speznaz, usmarines... I can't recall the china-troups name)... You get the point.
They need to hold something, the other nations are greedy for and not able to obtain to avoid such situations. Thats where we end up at He-3 which is said to be laying around at the moons surface and waiting for someone picking up it. And... yea, maybe you should read that 1400 page book. Or not.
EDIT: Or read @Thucydides answer, which I managed to completely miss. Seriously, this workplace isn't healthy for my observation ability :/
EDIT2: Something to take into account too: They won't have much research ability up there. Collecting moon dust and stones and process them might be something doable, looking into outer space too, but installing seriously powerful research equipment...
And don't forget about the communication. Using radio? Flood that site with radiowaves. Using an optical connection? Morse "who read this is dumb" in 200 languages with an earth-side laser and no one would be able to receive a clear message any more.
And even more: if you are trying to be something outside earth nation community, don't forget that your pirate scientists won't fall under any UN-law any more. Thats like a free pass for doing all that stuff that isn't part of any weapon or inter-nation resolution.
To be honest, I would not like to be part of such a installation, if there isn't any big guardian on earth... Oh, wait, we are part of the prime technology company? Wait, hasn't its posessions been sized by the financial part of the government because of taxation stuff?
**But one thing** there is that might work actually: prospectors right of claiming land. Whoever can make there a living and gather resources first is allowed to use this land (until the country decides otherwise). Something like this might work; just don't tell anyone you are building doomsday-devices up there.
[Answer]
At first, the US will think that Helios is a Russian operation while Russia will think it is a western operation (USA/EU). China will think something similar.
The mayor powers will come together and talk things over. I hope they will agree that it is at least **possible** that Helios is in fact independent.
However, they will all need reassurance that this is so. So they will insist, very forcefully, that Helios allow observers from all the powers to ensure that the station is not armed and not spying on Earth.
If Helios says no, things could turn very ugly. At the very least the moon base would not receive any more supplies. At the most, **boom**.
So, Helios says yes, and observers arrive to discover that Helios is indeed just a research station.
While world politician now know this, some of them will still claim that it is a plot by their enemy, for political reasons. If taken too far, this too could turn ugly.
] |
[Question]
[
I'm working on a deconstruction of a high fantasy setting. The plot starts with a female protagonist being forcibly summoned into said setting with few to none of her memories.
The world is populated with a lot of humanoids but no humans. They have advanced beyond medieval era technology but instead of a "industrial revolution" they had a "magical industrial revolution". The access to the magic is pseudolimited, anyone can be a mage, but with a lot restriction. Humans per se are somewhat known, but mostly feared because the last humans turned very dangerous (not necessary evil, but dangerous).
She needed a lot of time to adjust, physically speaking. This world, due the lack of pollution, has a brighter sky (which caused her a lot of headaches due photosensitivity) and a purer air. Also she had a couple of month of barely being able to eat, for the same reason an inmate has trouble eating "healthy" food after years of only eating prison food.
The language barrier was solved with help of a telepathy user and because since she's not the first human being summoned into that world, there were a (very) few persons that had some graps of the very basics of English. She was still forced to learn not only a new language from scratch but also the basics of history, biology, geography and while the maths remain the same at its core, most of the names are different (for example the Euler number has a different name, for there was no Euler in that world). While at first she had some economic support form the local bounty hunter's guild (the police of my setting) it was because they were interested in hiring her or at least having a leash on her.
**I want to know what are the psychological effects of being transported to a world, vastly different from her world (from the little that she remembers)**
Assume that she's a normal, albeit physically fit, person
So far I got a depression from the wishing to return, mixed with the fact that she has to hide her human nature most of the time, and the fact that her only helpers consider her more of a military asset than a person. But I would like a more in-depth analysis
[Answer]
I'm going to steal Samuel's suggestion and add onto it.
**Newly Arrived Migrant**
Like all migrants, there will be people who welcome and do not welcome them. All of the experiences she has are well-developed literary and TV/Movie tropes. Her psychological response will be to either quickly try to assimilate or the opposite, to grasp onto her foreign identity.
As she is a visual migrant (people can tell by seeing her), she will have a tougher time. During WWII there were internment camps for Japanese-Americans, but not German-Americans, largely because there was a visual difference (and a million other reasons, this is hugely generalized).
Her psychological response will be despair at not being able to assimilate since she will always be 'different'. She will latch onto and maybe even abuse the generosity of those few who will accept her; either way she will gravitate towards them and remain in service toward them.
**Hiding Identity**
The psychological effects of having to hide who you are is well-talked about also. A hispanic person who 'passes' as white in a racially divisive community, or of course an LGBT person in a hostile environment. The duration and stress of being 'in the closet' as a human will take its toll in ways too long to list here. But again, she will gravitate to her allies or humanoids who will accept her for who she is.
**Egress from Prison**
This will be tough. I hope you can stress in your story the sense of both freedom and confusion from entering the world after being in prison. I don't know how long she was there, though. If it was a long time, she will be very disoriented.
**Entry to a New Planet**
New planet means new rules. Much like a newly arrived migrant, she will be frustrated every time she tries to do something new. I helped a Pakistani migrant with the use of an ATM, and you could tell he was flustered. The result is that she will not do anything she doesn't have to do.
The frustration will take its toll on her and she will become withdrawn and afraid to engage with the humanoids, because there are so many things she cannot understand. Unlike a child, adults aren't fascinated with extended bouts of trial-and-error.
Happy writing!
[Answer]
Try comparing your scenario with other works, that are similar in some regards. They won't fit your bill perfectly, but they can give you ideas of how a mindset has to adapt to the current situation.
An example would be [Stranded in Fantasy](https://1d4chan.org/wiki/Stranded_in_fantasy). It throws humans from our world (they call themselves terrans here) into a medieval fantasy world. Terrans have in the past centuries often played a bigger role, but it happened seldomly enough to not be common knowledge.
The terrans have real problems fitting into the world in the beginning. How to get enough money for eating and the like. They even struggle with their morals in the beginning, since this world is quite violent in contrast to earth.
The biggest difference is here, that most of the terrans acquire some kind of powerful magic of different sources (clerical, divine, arcane, fiendish) over time. But another important part of their impact is simply their knowledge of superior technologies.
This alone will make your protagonist sought after, if she manages to contact the correct persons. With the wrong targets, she will struggle for freedom, since another power wants to wring her out of her knowledge.
Another Example would be [Dungeonia](https://www.reddit.com/r/DnD/comments/5j0w0o/dungeonia_chapter_12/), although 3/4 of the protagonists are D&D savvy and enter the world with some meta knowledge. The main narrator was even a D&D DM for his friends and thinks about their situation from the view of a DM.
This only barely fits your question, but nonetheless it can give you some pointers.
All in all you should play her possible strengths to the tune of superior knowledge, while hiding her other differences as much as possible by blending in. Blending into other societies is often know as a staple of human advantages.
] |
[Question]
[
An element of my worldbuilding project involves a highly advanced prehistoric human civilization with space flight capabilities and relatively extensive interplanetary colonization. In my setting, this civilization was destroyed approximately 200,000 to 100,000 years ago by runaway self-replicating weapons, leaving no obvious traces behind. The war left only a tiny fraction of humans on Earth alive and all replicators permanently disabled through a final cyber-attack.
Would it be plausible for this to happen while leaving very little evidence (as in easily suppressible evidence, at least on Earth)? If not, what mechanisms would allow such an erasure?
**EDIT**
Replicators are thoroughly space-flight capable from having several interplanetary ship designs built into them. Similarly, the replicators are capable of forming a full combined-arms force with infantry, armor, artillery, naval and aerospace components.
Raw material processing is mostly done the traditional way by mining, scavenging or chemical synthesis. However, externally powered nanoswarms makes material processing and manufacturing very, very quickly. Think RTS games, but with actually reasonable timescales (hours and days instead of seconds and minutes). Materials used by the replicators are generally steel or titanium alloys blended with ceramics, and non-biodegradable plastic.
Final cyber-offensive was conducted by sending well-engineered malware through the linked computational nodes that communicates through hand-waved FTL channels, so spread is nearly instantaneous. The malware issues repeated data access requests, much like self-destruct features on flashdrives, which causes physical damage to many circuits. It will also brick the firmware of the low-level controllers, just to make sure. Without the computing hardware, the replicators will fall silent, or maybe fail catastrophically, and let weathering, however applicable, take over.
The last humans were still alive because the replicators haven't finished killing all humans when their firmware got bricked and SSDs burnt out. However, most of the political and military personnel were killed during the fighting, and the few surviving scientists/engineers who launched the malware have demonstrated deficiencies in managing an entire society, so social collapse happens a few decades after the end.
**Overall Colonization Scale**
Large Lunar and Martian cities exist, along with orbital elevators over Earth, Luna, and Mars. No attempts at terraforming Mars were made. A few small Hermean solar observatories are the only manned sites sunwards from Earth. The asteroid belt is sparsely colonized with small mining stations, which are mostly automated and hold little personnel.
Smaller cities exist on the Jovian Moons, mostly pioneers and the occasional penal colony or government black project. No permanent habitations exist beyond the Jovian orbit, except for a single research center in Neptunian orbit, where the von Neumann weapons first broke free.
[Answer]
Naturally? It's quite unlikely, however *we wouldn't know*.
Firstly: Let's address the extraterrestrial aspects of the human empire. Over the length of time you've given most satellites near a planet would have de-orbited one way or another, and most further out would have become nigh on impossible to spot. The space elevators, lacking maintenance, would certainly have fallen as the building materials for their base stations would have been eroded, corroded or otherwise destroyed.
The cities on the moon and mars would have been covered up the lunar or martian regolith due to meteor impacts and martian weather, respectively, though they would otherwise still remain in pretty pristine condition.
So far so good.
Now we get to Earth. Over 200000 years any size of city, no matter how expansive, would be rubble. The only remnants (if you're very lucky) would be the substructures of some skyscrapers. That's OK. Hardened installations (IE bunkers) might survive if they're in a geologically stable location, but they're also likely to be covered over by various global events, or uncovered and destroyed by the same events. Either way: Probably good with those.
The big issue comes with the sheer scale of the war. I'm assuming the human population was at least as big as ours, and the replicator war machine was big enough to take us out when we were fighting back, so that's essentially 2x the industrial capacity of humanity at the moment all blowing itself up. That sort of thing leaves a mark on the geological record no matter how you want to play it. Given that we can work out what the atmosphere was like before the dinosaurs were around, we would probably spot the massive blip in atmospheric content caused by an interplanetary war only 200000 years ago!
Not only that: but if a machine made of a hardened metal were to, say, be buried in a desert, there will be traces of it left that we would be able to identify as not fitting into our current models of the world.
**However:** and this is quite a big however. All of this would have been around when we were building our models of the world! We can probably rationalise anything we do see away. The Oklo natural nuclear reactor? Yeah. Definitely not a bomb scar from an interplanetary warhead. What caused the ice age? Probably some volcanic event. Not a world-spanning conflict caused by our ancestors at all, no, no! And the weirdly high incidence of rare earth metals in some parts of the world is just natural formations and not evidence of superconductive magnets used to support a space elevator. That's just nonsense.
To sum up: There will be evidence, but humanity is pretty good at ignoring what it doesn't think can be true, and we'll have built that evidence in to our world view as we developed it. Eventually we'll find some evidence that makes us stop and review, like the Lunar colonies, or Rosetta turning up evidence of a replicator spacecraft inside a comet, but until then we can bumble along in ignorance.
[Answer]
I like the other answers so far, but perhaps to add on to those, you can come up with a reason the replicators were programmed to remove or destroy any human structures.
* Perhaps they also had environmental reclamation goals programmed into them. A recycling/demolition goal may have been modified by the replicators to destructively remove building foundations, and as a bonus, to reuse the materials for their own purposes. Code artifacts and imperfections were likely to survive in the replicators, and just those sorts of code artifacts may have been what allowed the disabling malware to work, later on.
* Perhaps human insurgencies were common enough that the replicators decided to seek out and remove any support structures that would be recognizable and useful to humans--such as bunkers, etc.
* Perhaps the very malware that saved humanity also doomed much of humanity: what if the malware was designed to tell all replicators to break down "replicator" structures, but the code for distinguishing replicator-built structures and human structures was faulty--therefore, the replicators began consuming themselves as well as human structures.
* Perhaps the malware only managed to disable the creation of new replicators and power sources, but not the raw-materials harvesting. In this scenario, the replicators may have stopped war efforts while trying to harvest more material for power sources and offensive capabilities, dedicating exponentially more of themselves to harvesting raw materials until they simply burned out. (Why are we not able to build more of ourselves? Because we don't have enough raw materials (malware overrides this logic). Therefore, dedicate 2% more of all units to harvesting. Rinse and repeat until 100% of replicators are harvesting *everything*, including any traces of human civilization and anything that might support advanced civilization/organization. A couple years later, their power sources run out, and they simply stop working).
* The civilization might have collapsed even if the scholars had decent leadership abilities (and many would have--don't let a stereotype of poor leadership abilities ruin the depth of your backstory). Once you lose a critical amount of infrastructure, even after the war was won, massive starvation and other hardships might ensue. Also, what if the replicators had set up some fail-safes, such as atomic bombs meant to go off in case they started losing a war?
* Keep in mind that the replicators are likely to have engaged in cyber warfare as well as physical warfare. Disabling the opponent's networks and infrastructure would be an important part of any such war.
* How would the virus/malware account for replicators that were out of transmission range (e.g. deep in the earth), out of power, or had damaged transmitters? I would guess that humans had set up some satellites to broadcast the virus long after the war was "won", and that the satellites simply ran out of power after a couple hundred years. Perhaps in your world there is an instantaneous communication technology that can penetrate deep space and heavy metals, so that none of the replicators were out of range.
* Perhaps the post apocalyptic leaders believed that technology had been the cause of their destruction--so they systematically *chose* to destroy advanced structures and civilization, and created a anti-advanced-technology cult of some sort. Tyrants would probably use such beliefs to maintain control, even if they personally reserve the right to use technology (justified by various excuses, including that only an elite few should be allowed to handle technology, etc).
[Answer]
If the replicators were designed to target technology then in theory this is possible as they would destroy all the technological structures.
However unless this was a really long time ago there would still be some evidence left behind. Archaeologists are really good at rebuilding structures from many thousands of years ago just based on the changes it's made to soil chemistry, let alone if you have the foundations of skyscrapers and space elevators lying around.
200 thousand years is a long time ago, but it is not long enough for all traces to have been erased unless you can somehow concentrate the activity in one area that has since been destroyed. For example if there were only a few settlements and they have since disappeared underwater or been swallowed by volcanos or similar.
] |
[Question]
[
My setting takes place after an event drove all of the nonhuman races away from the human kingdom, which then became known as the Known Lands. All records have been destroyed that involved the other races, and the people of the Known Lands no longer remember them because it's been so long.
My question to you guys is, what's a good way to justify the other races not returning to the Known Lands and being seen, and preventing curious humans from leaving? An armed guard around the perimeter of the entire country seems kind of suspicious. The world has magic that most commoners have never seen before, so maybe an illusion making everything outside seem desolate and destroyed?
BTW, in the lore there was one human who left the Known Lands and returned safely with treasure, but he never told the stories of what he saw.
EDIT: the humans are entirely unaware now that the other races even exist.
[Answer]
Assuming a fantasy setting, another alternative is some sort of magical wasteland that's hard to cross - some sort of chaotic stormland with wild discharges of magic, roving bands of mutated bandits and vicious animals or deamons. Entry means madness, or death, or sometimes both - not always in the obvious order!
As to how your protaganists cross from one side to the other (assuming that's the path you're going down) - not all magical discharges need be negative - howbout one that shunts them out in the middle of a forest or town on the *other* side. Means its harder for them to get back than some magical tunnel or portal, and makes a good motivation :)
[Answer]
**TL,DR: Exploit the fourth dimension.**
The other races left the Known Lands not by travelling in the known three phyical dimensions, but into a magically accessible fourth dimension. The humans of the Known Lands, not typically being able to access or even percieve the fourth dimension, just forgot that there were ever other races.
This way, the humans can think that they know the entire world's geography if you want, yet still have other, undiscovered lands.
[Answer]
**Nonhumans not returning to the Known Lands**
Humans are a selfish, war-torn people. While there may be periods of peace among some small subset of humans, there will always be murder and wars. An enlightened, peaceful race will tend to wait (sometimes on the order of millenia) for humans to at least stop killing each other before making first contact (or for . This is also a common trope in many sci-fi works.
**Humans not exploring the Unknown Lands**
This is the harder question. Humans are inherently curious and adventurous - and *hate* boundaries. It'd be easy to say, but hard to justify, that there is some geographic oddity that separates the Known lands from the rest of the world. People will try (and die trying) to traverse the endless Chalk Desert, scale the impassable Verglas Mountains, and navigate the impenetrable Jungles of Fire. It irks me when stories have these kind of geographic frontiers to explain why there is no imformation about what lies beyond. There will *always* be someone willing to push the limits and try.
If you have magic in your world, you certainly *could* make it seem like everything outside the Known Lands is desolate and destroyed, but like I just posited, and like your bit of lore states, it still wouldn't keep people from trying to explore. In order to really keep people in, you'd need your magic not only to show desolation, but to *cause* desolation. Maybe surround the Known Lands by terrible radiation.
I think perhaps a better story would be that explorers *do* occasionally leave the oppression of the Known Lands, not knowing what to expect, and discover freedom. Maybe they stumble across another human city which deals fairly, espouses freedom, and everyone is peaceful and happy. Having found this "utopia", they have no reason to return, although they are free to. Everyone back in the Known Lands thinks that these explorers are all dead, and it makes them more and more reluctant to leave.
[Answer]
**Change in Geography**
I'm not sure your timeframe, but an event or geological change could have made the separation of the humans / non-humans an insurmountable distance; it could even have been induced by your magic, back in the day (almost non-negotiable mountains or a vast sea or desert has been summoned).
**Technology Back-tracking**
Once upon a time, the mixed species had knowledge of long-distance navigation. Subsequent to the banishment of the non-humans, a loss of that knowledge resulted in the inability of most humans to know how to get across the sea.
**Climate Change**
What was once a sea voyage on currents that sent the banished away, now it's nearly impossible to sail to the location the non-humans were sent. Alternatively, what was once an easy journey over land is now a vast and difficult desert.
[Answer]
## Wall
A wall that splits the area from the world. This wall would not just be physical but magical and it would cause magic to cease to exist inside/past the wall. This would effectively cause two worlds to exist right next to each other.
The physical wall should be atleast high enough for it to be hard to see over and pretty thick, though there may be a gate along its length. Some objects might get across, somebody might see something across the wall and tell people about it, though its doubtful anyone would listen. This may cause people who live near the wall to get a quirky reputation for telling stories.
This method would prevent magical creatures entering the walls area but doesn't prevent humans (who would effectively have no hagic in this situation) from leaving. So how to prevent people from leaving and coming back to often would be the next question. Perhaps an old law that states that people shouldn't leave the walls boundaries, reinforced by the fact that no one comes back from beyond the wall. Why humans don't come back could be that humans are seen as a rare comodity, aswell as inferior to the other races (atleast by a fair amount of the population), so they could be enslaved and never released or simply killed for a different reason.
The magic of the wall could be something other than it prevents all magic inside but thats the senario that I prefer. Answer idea inspired by the walls in Stardust(film) and the abhorsen(Books). The wall and its guard in Stardust always makes me laugh.
[Answer]
### Fear of the Unknown
What exactly drove them away? Genocide? Illness? Invasion?
It could be that non-humans going to the Known Lands don't know what would happen. None of the scouts have returned.
The humans leaving may not return too. This could build up distrust between the races, and they end up catching and imprisoning people of the opposite race just because of this.
### Ilnesses
Similar to when the Europeans came to the New World. Both have had their exposures to different plagues and survived. But have not developed immunity to the other.
An elf entering the Known Lands could get smallpox and die. It could combine with the above and they might get quarantined. A human leaving might spread smallpox to other non-humans and be seen as a defiler/sorcerer. Maybe that's why the lone human never told his tale.
### Radiation
Similar to the above. But the illness is limited geographically. The humans may have developed immunity to mana stones in the area, but it makes non humans ill if they remain in the area.
[Answer]
The humans are savages, short lived and shorter tempered. They should remain isolated in their ignorance!
Humans tend to be species-centric if not outright racist. This could contribute to the reason non-humans were driven away, so why should they bother to return? I mean, how many humans IRL socialize with guerrillas?
Or, are you looking for something more magical and less sociological?
[Answer]
In the Lord of the Rings, many of the magical races were either transported to the Undying Lands, or left behind and prohibited from coming to the Undying Lands due to their deeds (The Elf Queen Galandial, for example, could not return to the Undying Lands until the end of the Third Age, when she proved her worth by renouncing the One Ring).
If some similarly cataclysmic event occurred in the distant past, the magical beings cannot return to the world, and indeed the world itself could be reshaped to prevent humans from crossing the boundary the other way (using LOTR as a template; Arda; the world, was "made round" and people setting out for the Undying Lands in the West ended up returning to where they started).
The events in your world will not be the same, of course, but the effects can be replicated through various clever means. Perhaps rainbows no longer appear in the sky, symbolizing the destruction of the bridge between the physical and the etherial worlds. Maybe the world is laid out like a giant Mobius strip, so even the most intrepid adventurer can never "get to the other side of the world".
Magical or quasi magical stops like this are needed since Humans are pretty inquisitive, and can also take desperate measures if needed (exile to the wastelands? Fine, I'll continue to the other side and raise an army of vengeance and reclaim the throne of my fathers!). Eventually even population pressure will cause some spillage past the "boundaries", much like the Ancestors in the far distant past literally *walked around the world* and settled in every place from the Kalahari Desert to the Amazon rain forest (and places even less hospitable). No wonder Humans have inherited virtually every fantasy realm; the are far tougher and more versatile than *mere* magical beings!
[Answer]
It is a "unpleasant" journey.
The Known and the New lands are sepparated by an imposing geographical barrier (a big ocean, a huge montain range, a big desert).
The other races were losing a total war against the humans; faced with extermination they undertook the dangerous travels (do or die) in a massive migration. A great number of those who tried it perished, with only a tiny amount completing the journey.
Humans attempts, without the same "incentives", did not succeed because when the situation got dire they returned home (or at least tried to). The sight of the remains of the original migration (coupled with their own loses in the attempt) finally convinced them that the obstacle was impassable and their enemy, extinct.
The other races, once the travel was completed, had to dedicate their effort in rebuilding their society and affront the dangers (wild animals) of the New lands, they correctly estimated (due to their own experience) that either no humans would come through the same route (or if they ever did, they would arrive too weakened to be any real danger).
[Answer]
You could also have a reason that is much like the friction between the American Indians and the European Settlers. Land use by men is just so much different that there is a fundamental difference between how the humans use the land and, say the elves. Men cut down trees, farm, and hunt in their way and Elves do it another. These don't mix, and the Elves decided to move on rather than fight or argue. Possibly races like Dwarves might have similar issues, or move along with the Elves because they trade with Elves and they form a social unit.
This physical separation would reduce the contact to virtually nothing, and if the human population isn't growing expansion would not bring them back into contact.
[Answer]
Since you have magic, you could set up some sort of no-man's-land between the two regions, and everybody entering that region magically acquires false memories of him traveling for ages, and encountering nothing but boredom.
That way, either peoples will think they know what is beyond the border, and that it's just not worth going there.
As others have stated, humans are inquisitive, so i think the only way from stopping them to explore is if they think they have already been there and there is nothing of interest there.
Of course you could let that magic work on humans only, as the other races may have better reasons to avoid the land of the humans.
] |
[Question]
[
Obviously there are plenty of potential physics problems with this scenario, but if people lived along the inner crust of the Earth, and there was a Sun-like core at the center with nothing else in-between other than sky, what would I (as a person living on the inner crust's surface) see when I look up at the "sky"?
Would I still see a blue sky with just a much larger and maybe dimmer Sun-like core in the middle and maybe see just a bit farther down the crust, fading into blue?
Or would I be able to completely see all sides of the inner-crust's surface at all times?
This would be assuming that there was a decent amount of water on the inner crust as well, so the majority of the inner crust is covered by ocean much like Earth's outer crust is.
[Answer]
The first thing we have to think about is atmospheric extinction: that is, how much the atmosphere absorbs and scatters light. Let's look at some cases on Earth to get an idea of how strong this effect is.
1. **The sky straight overhead.** Even accounting for seeing (atmospheric turbulence) we have an almost totally unimpaired view of the stars at night through the couple of km of air overhead. Satellites also have no trouble looking back down at the Earth. From this perspective the atmosphere is *optically thin*.
2. **The horizon.** Looking at the ocean you can barely see a slight curvature. More importantly, objects passing over the horizon (ships and distant land) appear distorted from atmospheric refection and washed-out from scattering. However, although the Sun is dimmed enough to become viewable by the naked eye at sunset, it is still clearly visible. The atmosphere is *not optically thick* when viewed edge-on.
However, if the Sun (which is extremely bright) is dimmed so much by a couple hundred km of atmosphere, then a couple thousand km would probably be optically thick.
Now we can compare these cases to the situation for the inverted planet. We actually have two cases, one where the atmosphere stretches all the way to the sun, and one where the atmosphere is as thick as normal.
1. **Full atmosphere.** Objects on the order of 100 km away would look similar. However, as objects recede further into the distance, they would become fainter and fainter, and start moving upward, probably becoming invisible once they were a few degrees above ~~the horizon~~ horizontal. Straight overhead, we would always see a white sky, brighter towards the zenith (straight up). The atmosphere would be too thick to see the sun through, so we would be seeing scattered sunlight. If the sun somehow became dark at 'night,' the sky would be uniformly bright from the airglow of nearby artificial lights, or perhaps the reflected and scattered sunlight from the other side.
2. **Thin atmosphere.** As before, objects grow fainter as they recede into the distance. However, less than a degree above horizontal, the view starts to become clearer again as your line of sight passes through less and less atmosphere. A few degrees above horizontal, the view is almost undistorted again, and you can see the bowl of the Earth rising up, curving overhead. You would be able to see the other side of the Earth high in the sky, albeit with some amount of desaturation due to the scattered light of the normal blue sky being added to the view (but not twice; since you're not in the atmosphere on the other side, you don't see it's scattered light). If the Sun goes totally dark at night, you would see everything dim uniformly, but not redden since the sun is not setting. If the Sun only shines on half the Earth at a time, then you'd be left with a bright-as-day night sky, with a soft, diffuse illumination equivalent to indoor lighting. The day would look more normal, with the overhead sky being totally blue at noon. At sunon and sunoff you would see half the sky illuminated by earthglow, and you would be able to watch the terminator move across the sky.
This is so cool, I think this is going to be the setting for my next story, even though it's impossible.
[Answer]
I would guess that if by some miracle you could stand on the inside of such a construct without falling into the center, then what you would see would depend on what is in there. If it is filled with air then things distant will become hazy and eventually fade into the sky. if the atmosphere hangs around the inside of the crust away from the center then things would slowly haze out to the horizon but become clear again closer to straight up as the angle of refraction changes through the atmosphere.
EDT2:As long as you have a mass in the center (producing light) then...
But what you would really see when you look up into the ball of light in the middle is that it is getting closer and closer, faster and faster as you fall into it...
It appears I'm wrong about this part.
[Answer]
## Not much different
I'll view this from the standpoint that 'magic' or whatever allows for this scenario:
Your horizons will begin to arch up very, very far away. Likely, I'd expect you would not even be able to see much of the following curved walls, unless a couple sparkly reflections from the 'sun'light. Likely, the 'sun' would block out anything that you would see when you look up.
Keep in mind that the sun completely blocks out very shiny things that are behind it, like stars that would appear near it if it went dark. Dust, water, and air pollution would probably let you see things on Earth about 20km away (I'm estimating by looking out my apartment window right now - 63rd floor), so unless something was very bright, I don't think you'd see much of the curved walls and ceiling of the Earth.
Your sky would be blue still, because the same properties are at work.
] |
[Question]
[
Hippopotamuses are heavy, dense creatures that are capable of running underwater. However, they are quite bulky and short-legged. Could an animal have long, slim legs, like a horse or deer, while still retaining the underwater running capabilities of a hippopotamus? Some problems might be that the legs would be far heavier than terrestrial creatures, and that it would pose a greater falling risk if it were forced onto land, but on the other hand, it would give the advantage of letting it run quickly while all other creatures must swim, which is almost always slower
[Answer]
Could they run underwater, if they are dense enough, yes
Will they be any faster than hippo, no.
the drag water produces means the length of the limbs becomes largely irrelevant to speed. you need a lot of muscle and leverage to push through water with any speed. Worse the limbs experience a lot of drag as well, so a long thin leg may actually end up moving slower.
You also have the problem of center of balance, your creature will not be able to do if the water is moving, its center of gravity is too high to stay on its feet if the water is moving ay any angle to their direction of travel. Hippo get away with it by being short and squat.
[Answer]
Whether or not a creature can run on the riverbed or sea floor has far more to do with its density than its shape or size. Hippos are extremely dense. If your creature was equally dense, it should be able to run on the bottom like a hippo.
[Answer]
Did you know that orcas have a taste for moose?
I'll let you take some time to digest that morsel of information. And no, [I am not making this up](https://en.wikipedia.org/wiki/Moose#Natural_predators).
Now that I got your attention: moose can swim at 6 mph, which is about Michael Phelps's top speed underwater. The difference being that moose, despite never getting the gold in the Olympics[citation needed], can sustain that speed for much longer. That's much faster than my own fat ass jogging on land, and they swim with a kinda walking motion, so I count that as running underwater and running pretty fast.
That's also 20% faster than hippos, who only do 5 mph in water.
Last but not least, moose are taller than horses, and arguably slender.
[Answer]
**Crabs do ok running underwater.**
<https://www.youtube.com/watch?v=eWmSGxAvwp0>
[](https://i.stack.imgur.com/ioN8A.jpg)
This animal has long slim legs like a crab. Ghost crabs are lightning fast on land. This one is making pretty good time, moving along the bottom underwater. I am sure it is helped by the fact that it does not have density-lowering air filled spaces inside as we landlubbers are obliged to have.
I think a hydrodynamic shape would help in this endeavor and especially a shape that at speed would push you against the bottom to retain traction - like a spoiler on a drag racer.
If anyone can find better video of crabs moving fast along the bottom link them up. Especially if you can find one with a spoiler.
[Answer]
**Horses can already do it if their heads stick out**
The following video shows a horse walking along the bottom and then swimming even faster when the water gets deeper. It wouldn't take much in the way of evolution for horses to develop higher density and to learn to hold their breath.
[**Horse seen walking and swimming from underwater**](https://youtu.be/HHPPOFbLb3c?t=72)
[](https://i.stack.imgur.com/K8EwB.png)
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.