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I know that this would, perhaps, be biologically impossible, but suppose it's possible, how would such person see?
I know that cats have a vertical adjustable pupil and goats have a horizontal one, mixing both would be something kind of like this (I made a trashy editing on a cat eye just to demonstrate):
[](https://i.stack.imgur.com/5H3U6.jpg)
It wouldn't be permanent, i.e., the pupil would be able to adjust itself from a cross-shaped pupil to a round one.
A pupil like that would offer any benefits? What would be the disadvantages?
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In [this answer](https://worldbuilding.stackexchange.com/questions/57683/what-would-people-with-black-eyes-see/57688#57688) I noted reasons why an optical instrument (that happens to be part of a living creature) would want a *large* aperture. That made me think about slit pupils at the time, though I did not mention it in that post.
# Depth of Field
Do you know how auto-focus works on dSLR cameras, and the “split prism” people used before that? The *phase matching* works by taking light from each side of the aperture separately and comparing the separate images. This only works if the aperture is in fact large enough to have separated sides.
Now arguably a smaller aperture provides a sharper image already. But the wider aperture allows for accurate ranging: the determination of distance to an object, rather than just seeing it sharply.
This is the effect aluded to by the articles linked by Mołot’s comments.
Now consider this question on the Photography SE: [*What's the difference between cross-type autofocus points and regular ones?*](https://photo.stackexchange.com/questions/9785)
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> cross-type sensor is simply two linear sensors crossing each other (making a cross shape), which is superior because it can work with both vertical and horizontal light patterns.
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A cross-shaped pupil allows for the angular resolution of a large aperture, while masking off the excess light from the large area of such an opening.
Cameras find it advantageous to use cross shapes rather than slits, so they can focus on a larger variety of objects. An animal may find the same advantage.
## [phase or contrast focus](https://photo.stackexchange.com/q/20474/33948)
Note that the principle is the same regardless of whether the light from each edge is sensed separately. If separate sensing is used, the features can be matched and this is called *phase*. For a single image taken with an extended aperture, you simply judge the sharpness of the image. In either case, we exploit the physics responsible for reducing the depth of field as we increase the physical size of the aperture.
# Diffraction Limited Optics
In the case of an instrument working at full aperture to get angular resolution, the implication is that a larger aperture can produce a sharper image (of the in-focus item). In the case of synthetic aperture instruments the cross-shape ought to provide the additional information. However, I don’t know if a simple projection onto a retina would be sharper or not: the blurring due to [*diffraction*](https://en.wikipedia.org/wiki/Diffraction-limited_system) might be caused by the narrow parts and having wide parts as well doesn’t un-blur it.
But you could imagine that the optical system behind that alien aperture is *not* like a mammal’s. It could be something designed to indeed have a high angular resolution needing a mimimum physical aperture size.
# Wierd Eyes
From Mołot’s links, we see that some animals have various special features in the eyes, like multiple fovia or some kind of separate zones for different colors. The shape of the pupil might not make sense if you assume that the eye is otherwise *just like ours*, but is part of a complete system.
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This is, indeed, biologically impractical. Pupils are controlled by small muscles, which cannot "push", only "pull". The muscles to pull a cross-shaped pupil into a narrower cross would need to cross the centre of the pupil, which would definitely interfere with vision.
Ignoring that problem, there don't seem to be major advantages for humans. The Wikipedia article on [pupils](https://en.wikipedia.org/wiki/Pupil#Other_animals) has some hypotheses on why some animals have non-circular pupils, but the summary is that we don't yet understand this in detail. Slit pupils seem to be mostly found in animals that are active at dusk and during the day; they can close more completely than circular pupils, which is helpful for creatures with very sensitive retinas.
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Perhaps this pupil shape allows for polarization of incoming light, or acts like a slit to allow for diffraction. The retina could have a pattern of very specialized photoreceptors that use the diffraction pattern for very high sensitivity vision. So rather than have a homogenous mix of photoreceptors across the retina that get exposed to plain light from a round pupil, the retina exploits diffraction to have photoreceptors of specific wavelengths set up in a pattern based on the diffracted wavelengths. Slit light diffraction and polarization interactions are discussed [here](http://users.wfu.edu/ucerkb/Phy114/L16-Diffraction_Polarization.pdf) *which I link simply because it is from my alma mater :)*
Why would this be helpful? Maybe for increased sensitivity to specific wavelengths of light, like if this animal is a predator at dusk when most of the light is reddish, or in caves with phosphorescent lighting of a narrow wavelength. It still needs general vision when out and about, but for "hunting mode" it can form various slit patterns to see in different types of light.
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One thing that a weird-shaped eye could do is gauge distance a particular way.
If you imagine the cross-pupil closing entirely and a pinhole forming on each tip of the cross, the eye would see several images at once.
Some ambush predators use something like this to know when to strike; when the images line up the prey is in at the perfect distance for the predator to strike. Or, they would be able to look in several directions at once, with the same eye. Or, just gauge depth with just one eye.
There's also W-shaped pupils (cuttlefish) that do something similar; the prey is at the right distance when the image isn't distorted in an n or u shape.
An X-shaped pupil isn't very far fetched I'd say. It could evolve from something like the horse's corpora nigra, or something like expanding flanges that form the crescent-shaped pupils of skates.
Source: <http://www.koryoswrites.com/nonfiction/the-functions-of-different-pupil-shapes/>
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Based on reading one of the answers to this question
[Effects of "know before you vote" political system](https://worldbuilding.stackexchange.com/questions/46025/effects-of-know-before-you-vote-political-system) I started wondering if a system openly based on money could work and also be acceptable to the voters. The system would work like this:
For each piece of legislation / appointment to political office / referendum there would be an announcement of the date to vote by. Anyone not casting their vote in time results in that vote being lost.
All adults are eligible to vote and each vote holds equal power. (consideration of what defines an adult are not part of the scope of the question)
You may cast your vote at any time between the initial announcement and the closing of the vote. Counts of votes already cast become public knowledge so people can see what is 'winning'.
At any time you may sell your unused vote to another person for a value agreed between the two of you. Total free market here, it's worth exactly what someone will give you for it. That person then either sells it on or uses it to vote with in the way they want. Essentially you have a free market in votes much like shares in a company today. The government takes 10% of the money you get for your vote in tax to help fund itself.
Under this set of rules you would either vote the way you wanted to vote or sell off that right for whatever price you could get.
Under this system I see the poorest parts of society selling their votes on matters they didn't deem directly affected them quite quickly so it would be possible for people with deep pockets to get the result they wanted.
On issues that were close I see people holding onto their vote for longer as the value potentially rises the closer it got to the deadline.
Quickly people will understand that it's stupid to personally vote unless you have to be 100% certain your vote goes the way you want. For example on Important-Issue-12345 I may personally want the vote to be 'yes' and so would other people. If I can find a person or organisation that also wants the outcome to be 'yes' and I can reasonably trust them to vote the way they are publicly campaigning then I can sell them my vote, get the result I would have voted for and some cash!
On a personal level people would be playing the market to get either the most money or the most money they can with the outcome they wanted.
We can ignore any problems in the machinery needed for this system to happen (no worries about getting your money or being forced to hand over your vote under threat of violence etc) but consider problems inherent in the system (just because the person buying your vote says they will use it one way doesn't mean they have to).
companies could exist to simply trade on votes to make a profit. You would be allowed to sell your vote in the 'future' or for a period of time? Someone in need of money for say a debt or a deposit may deem it necessary to sell their voting rights for a year without knowing what issue would be voted for in that time.
Given the framework (lets call it the true-capitalist-democracy) would the system work? Is there too much of a concentration of money already in the hands of a tiny minority to mean that is becomes a total dictatorship? Is it really that different than the huge 'campaign funds' and lobbying gathered by existing political parties during properly 'democratic' voting that we have in the western world today?
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In practice the current American election system is already monetized. Statistically speaking, the candidate that spends the most money on the campaign trail will be elected most of the time. Using True-Capitalist-Democracy this outcome simply becomes more certain. Or does it?
**Firstly, we must assume that everyone will be willing to sell their vote for a price.** As the vote market stabilizes, it will become clear where the median price lies, and vote prices will likely take on a [Chi-Squared](https://en.wikipedia.org/wiki/Chi-squared_distribution) style distribution around this "average" price. To buy your candidates election, you simply have to be willing to fork over more cash than the other guy.
**Secondly, we're going to have to assume there will always be holdouts.** Certain people will refuse to sell their vote, or they will have a higher price if they do. Depending on the election issues, this may even create a secondary price bubble (similar to the kind of [double-peaked price distribution](http://metrocosm.com/why-is-the-rent-in-nyc-so-high/) a black market creates inside a regulated market).
I expect this second price peak will always exist more or less, which brings me to my third point: **people will be more likely to sell their vote for a lower price if they know their vote is not "being wasted,"** so to speak. Basically, a republican will sell for cheaper to the republican party than to the democrats, and vice versa. This will affect the market more significantly during election with vast polarization. For example: in the current election I suspect there are democrats who would literally rather die than sell their votes to the republicans, and who would probably sell to the democrats for very cheap. This will dramatically widen the price peak gap, making it very easier for the parties to buy votes from sympathizers rather than from opponents.
So what's likely to develop is a heavy reliance on campaigning to bring as many votes from the opposing party to the sympathetic party while simultaneously bolstering the sentiments of the sympathetic party. This will ultimately drive down the cost of buying their votes. However, since campaigning costs money, a balance will probably develop between spending on the campaign and spending on votes. It would be up to the campaign manager to balance the budget and get the most bang for the buck, much like they do today but with the added consideration of vote prices on top of everything else. **This is not very different than the system we have now, except votes are being bought and sold outright, rather the indirectly.**
There is, however, one majorly disturbing possibility that might arise: Investment Banking. **It is very, very likely that banks will end up in control of the government.** "Whoah whoah whoah; where did THAT come from?" you might ask. Well, it's actually rather simple, though it will take years to happen. As votes become a market asset, banks will begin investing in them. At first the market will be very volatile, but as the banks invest in more votes they will begin to temper things and start acting like a buffer between the public and the candidates. People will no longer have to sell directly to the campaign, but can now sell to brokers which will streamline the process. Prices will become more regulated and the campaigners will not have to focus so much on public campaigning as private meet-and-greets with brokers and bankers. Banks themselves will instead have to advertise in order to get people to sell to them rather than to a different bank. But wait a second, all of a sudden things are backward: candidates are lobbying with banks, and banks are campaigning for votes! With the voting power in their pockets, banks are now the ones electing officials, and they can firmly remind the candidates of this every election year.
Welcome to your new Puppet Government!
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I think it would not work out the way you imagine.
The first thing that would happen would be a new standard employment agreement: "As a condition of employment, I agree to sell all my votes to my employer, for no further compensation beyond my salary." Sure, if you have a job with any sort of leverage, you might be able to negotiate, but everyone working minimum wage will be forced to sign such agreements. McDonalds and Walmart would permanently own about 1%, each, of the votes to be cast.
Slumlords would try the same thing as conditions for renting apartments. The only thing holding them back would be the number of their tenants who sold their votes to their employers.
There is no surer path to superlative exploitation of the working poor than a scheme like this.
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This will lead to wild abuse of the voting system. Yes, even more so than what we see today.
Quite simply, most people (especially the young) don't realize how valuable their votes are - voting rates are typically quite abysmal. Add to this the fact that in today's materialistic, instant gratification society people always want a new phone, ipad, etc. and you're basically destroying what little democracy we all have left.
You see, in today's world politicians have to spend millions of dollars to try and convince us to vote for them. They also lie, and make wild promises. Is it perfect? Heck no.
But in your version of democracy rich interest groups will simply offer people cash for their votes. Teenagers will line up to sell their vote for $100 - or less. Buyers will go around ghetoes and poor neighborhoods offerring people a few bucks, cash, for their vote. It's going to be incredibly simple for a candidate to buy up hundreds of thousands of votes in any election.
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> But Andrei - you might say - when people catch on that the rich are buying their votes they'll just ask for more money! Free market capitalism and all that. Eventually even the rich won't be able to afford to buy all that many votes.
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Yes, and no. Sure, some people might catch on that they can sell their votes for a mint. But for every person asking for $100K there's 10 crack heads who would sign theirs over for a hit of their favorite drug.
Furthermore, you open the door to abuse such as people selling their vote under duress, foreign interest groups influencing elections, and many, many other complications.
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> **Example 2:** An extremist sect announces a candidate. This candidate is "universally hated", however the group backing him succeeds in buying a large number of votes covertly, and he either wins, or at the very least secures a position in government for himself.
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Do you see in how many ways this could go wrong?
The principle of democracy is that everyone is equal under the law, and everyone gets a say in elections. You may choose to abstain from voting, but *selling* your vote? You may as well start selling people into slavery next.
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### Edit to answer OP's comment:
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> ***"it occurred to me that it might actually be a way to convince the disenfranchised that their vote has a value." - OP***
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The very first time you use this system an interest group is going to exploit the situation better than anyone else, and of course win. Now in power they will realize that come next election they're going to face a lot more competition for buying votes because other people will have caught on as to how to do this as well.
So the people in power will start legislating under what circumstances votes can be sold, or in exchange for how much money, etc. such that they maintain an advantage in the next election cycle.
As far as people accepting that their votes have value: *they will*, but ***not*** in a good way. The reason many people don't vote is because they each think:
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And in a way they're correct - 1 vote doesn't make an impact. But a few hundred thousand people thinking the same thing sure does. However, you will replace that mentality with:
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> **"My vote is worth $XXX! I can buy YYY with that! Sweet!"**
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They will start valuing their votes, yes, but not in the context of shaping their country, only in the context of what material gain they can get in exchange for selling it.
[Answer]
### Can candidates buy elections?
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Money matters more to challengers than incumbents. The challenger needs to introduce herself or himself to the electorate and explain why the electorate should vote differently. Communicating with people takes money.
Incumbents have less need for money. It's noteworthy that many of the biggest fundraisers aren't in competitive elections but simply ambitious. A Nancy Pelosi or Paul Ryan raises money to support challengers. A side effect (or the main effect if you're cynical) is to leave successful challengers beholden to the donor. And Pelosi/Ryan are able to donate much larger sums than a typical donor.
If both sides are well known, money doesn't seem to be as important. There have been several elections where one candidate outspent the other and lost. For example, in 2010, both the governor and senate races in California involved candidates who were independently wealthy and could outspend their opponents.
In elections where the winner outspent the loser, it's not evident that the money mattered. The causality might have been that someone was more popular, so they both won and outraised their opponent. The 2012 US presidential election is an example of this. Obama was more popular than Mitt Romney, so he raised more money and outspent him.
This system would make that system work. Very few people say that the fundamental problem with politics is that it just isn't corrupt enough. This system legitimizes corruption.
### Money too concentrated?
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Currently there are different opinions among the rich. Some are conservative, some liberal, some authoritarian, and some libertarian. The largest problem here is not the people who control the money but the corporations.
Corporations will be incented to grab control. To them, it's just another expense. Buy coal and iron to make steel. Buy votes so as to be able to burn the coal in your factory..
What if the system blocks corporations? Then you'll find that such businesses will switch to structures that do allow them to buy votes. People like George Soros and the Koch brothers may be able to make money directly. Votes cost $1 billion. But create $10 billion in income. That increases the concentration of wealth that was already concerning.
### No checks and balances
One of the things that keeps government weak is the system of checks and balances. This bypasses that. Just buy enough votes and you can pass whatever you want. Then the government gives you more money, so you can buy more votes, and give yourself more money.
All it takes is one election. Someone says that they want to do one thing, e.g. reform law enforcement to reduce the number of fatal shootings by police. Then they win and do something totally different. But there is nothing holding them to their original platform. They've already bought the authority that they need.
### Too few voters
Some voters would refuse to sell their vote. But the majority of people don't vote. What's to keep them from selling their vote? It's not like they were going to use it.
How might something like this work? We do have an example of a system where large numbers of people were given small shares of a large organization. After the fall of the Soviet Union, one privatization method was to give all the employees shares in their factory or whatever. And we know what happened. Most, instead of keeping the shares, sold them immediately to whomever would give them money for them. As a result, business ownership in Russia is very concentrated.
People are notoriously bad at valuing things like this. You argue that people may suddenly value their vote because they can sell it. It's just as likely that the reverse would happen. If people can sell their votes, then that takes the burden away from them. Just sell it, and let someone else worry about it.
Look at the primaries in the US presidential election this year (2016). Instead of nominating two broadly popular candidates, the two parties nominated the two most disliked candidates ever. How? Most people didn't vote.
Much has been made about Trump getting more votes than any other Republican primary candidate, ever. Yet all the candidates combined received fewer votes than Mitt Romney received in losing the 2012 general election. Think of how much money you could save by picking *both* candidates in the primaries. And then the general election is easy, as you have no serious competition.
Why didn't people value their votes enough to vote in the primaries? The candidates were better then, particularly on the Republican side. Yet most people didn't value their vote enough to use it. Will such people value their vote enough to hold out for a good price?
Especially dangerous is the idea of selling your vote to someone who agrees with you. What if they lie? There would be tremendous incentive to misrepresent your position when buying a vote. What if you promise to do more research because you are undecided? That appeal might work for someone who is unsure. Doesn't it sound great to let someone else do the hard work to make this difficult decision for you?
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It would probably work better than most might think. For one thing, you would immediately increase the total percentage of the population interested in and involved with politics, even if only out of speculation. Lots of people would keep track of issues just to see what might become valuable, etc.
As a decision making mechanism, it would work, but with some caveats. What you are gaining by having more people involved in the decision making process, you are probably losing by people making decisions not based on what they think is best per se, but what they can get the most money for. The society at large might start to look like a true plutocracy over time, or evolve in ways similar to the once popular "cyberpunk" genre, with dozens of competing "megacorps" with opposing takes on issues that effect their bottom line and a weak central government. In history, societies based almost entirely around mercantilism, trade, and money have existed and (obviously) prospered for a time, but over the course of time, they tend to become unstable. In ancient Athens, there were mechanisms for the rich to buy more influence in the democratic system. In the middle ages, several city states held "elections" that more or less handed the government over to the most prosperous merchant family. In renaissance Italy, this sort of effect led to a period of chaos as rival wealthy factions competed for power using eminently buyable mercenary armies.
What tends to happen is that over time, the society stops being able to make intelligent decisions of self preservation that go against it's own short term economic interest. Outsiders used money to buy influence at the table and undermine Athens' security. City states likewise made good short term decisions and bad long term decisions based on trade interests that got them in trouble with much bigger and stronger kingdoms, etc. The ability to "buy" a large hunk of the political power of a society tends to work okay so long as that purchase is coming from inside the society. When outsiders (who do not have the long term interest of that society in mind) figure out how to buy influence, Athens gets taken over by Alexander or Rome or whomever.
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In my world there are androids.
These robots look just like humans; you cannot tell them apart from a real person by looking at them, inspecting their bodies etc.
To attain this they need some mimicry of human physiology. Making a skeleton is easy but what about muscles? Muscles are probably the most evident feature other than the skin. Are there artificial muscles that can mimic humans' in terms of appearance?
They must feel like muscles: squishy, no clanking sounds, at least strong enough to move the body of the robot. I do not care what they look like, as they are covered by the skin.
**How might they have these muscles?**
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**Yes**, there are(in theory, and at some scale in lab)
This video [Giant Stroke Artifical Muscles](https://www.youtube.com/watch?v=xMGXqT0LWUI) exactly about that stuff you are looking for, for same purposes you looking for, some very early early stage demos included.
Possible theory how some stuff might work: [Carbon Nanotube Torsional Actuator Mechanism](https://www.youtube.com/watch?v=Qzg2qA1ltK0)
This one if done on finer scale or covered with decorative layer also might be used:
[Hydraulic McKibben Muscles](https://www.youtube.com/watch?v=NDQlOqsr84s)
This interesting [PVC\_Gel\_Artificial\_Muscle](https://www.youtube.com/watch?v=dJl2gFUgkEc)
although need some technical imagination and a bit of fantasy.
This can be used to at least to mimic under skin movements [Elastomeric Escapisms - Electroactive Polymers](https://youtu.be/aBAzjJwFkS0?t=64)
This theory [Fishing Line Artificial Muscles](https://www.youtube.com/watch?v=Tba8Nf02OSI) simple, cheap.
This is how it works in lab [Artificial Muscle Fibre](https://youtu.be/Za0VeU9Ov7A?t=120)
Overall this direction of researches is researched, exactly for things like you mention.
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The thing you wish for already exists, Nitinol wires, otherwise known as "muscle wire". From the following link:
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> "Muscle Wire" is the perfect name for this product because it can be described exactly as it sounds: It is a unique type of wire that acts like the muscles in our bodies. Muscle Wire is an extremely thin wire made from Nitinol (a nickel-titanium alloy) that is known for its ability to contract when an electric current is applied.
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> Although thin and lightweight, one of the most amazing things about Muscle Wire is that they can lift many times their weight and are able to do 100 times more work per cycle than the human muscle. This material is easy to use, small in size, operates silently, has a high strength-to-weight ratio, and is easily activated using AC or DC power. This technology is ideal where mechanics require minimization, such as electronic textiles projects, robotics or nano-applications.
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<https://www.jameco.com/Jameco/workshop/ProductNews/musclewire.html>
You can use those as a core, then pad them out with a gel or some other material (perhaps even wrapping each wire in a tube) to make the muscles feel human to the touch through the android's skin.
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Amazingly enough, if you wanted to, you could make a robot with *real* muscles by growing live muscle cell cultures over a metal skeleton. In fact, [someone already did just that](http://www.popsci.com/soft-robotic-stingray#page-2).
That's a robotic stingray powered by rat heart muscle cells. Bio-robotic engineering at its finest.
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[Nitinol muscle wire](https://www.edge-techind.com/Products/Refractory-Metals/Titanium/Nitinol/Nitinol-Muscle-Wire-795-1.html) (also named as shape memory actuator wire) presents many intriguing possibilities for robotics. Nitinol actuator wires are able to contract with significant force, and can be useful in many applications where a servo motor or solenoid might be considered.
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Well, they exist already, apart from the 2 mentioned above this one, which acts like almost a human muscle. In fact they are being researched as artificial muscles
<https://en.wikipedia.org/wiki/Electroactive_polymers>
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I would like to have a small orb, producing light of proportions of a standard household bulb today. No big deal, right. They have these already for [sale](http://rads.stackoverflow.com/amzn/click/B004IDG6XK) on Amazon as night lights.
I would, however, like to create a floating version of this, anchored above shoulder height of its owner, providing a moving, ambient luminescence.
***Some considerations:***
1. Power- *This light should be able to last for months on end.* I envisioned something powered by possibly a small *RTG*, as it would supply constant power for long periods of time.
2. Staying Airborne- I would prefer for this light to be perfectly spherical, with no large protuberances. *How could I make this lighter than air?*
3. Cost- I'm sure its no difficulty making one of these expensive, and I originally intended only the wealthiest class to be able to afford them readily.
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I don't feel committed enough to this small facet to change the time period from that which I was originally imagining: No more than 400 years into the near-future. Assume, for example, that aside from cheap-spaceflight, we are still bound to our solar system by failing to achieve FTL travel.
***How do I make a glowing, floating, and long-lived light source that can be used in every day situations?***
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I would like to keep this as realistic as possible. Not too much handwavium.
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You don't even need to go all super-futuristic for this. It's almost possible today. Get a balloon filled with helium, and put a small LED button-battery powered light source inside it. Secure it with some ultra-fine fishing line, attach the other end to your clothing, and you're basically done.
Now if you want it to look nicer and slightly more future-techy, you can replace the balloon with specially molded ultra-thin lightweight composite, maybe with a well-placed strut to keep the LED centralized (and possibly provide an external power switch and means of replacing the battery), and replace and the fishing line with carbon mono-filament. Anything else is just over-engineering.
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To make an object light enough to levitate without a large engine, rotors etc, arrange for the light to receive power remotely. Inside a building or around the perimeter of the yard are microwave emitters which provide the energy to power the lamp, and the associated systems that keep it flying.
If it is light enough, I would go for Electrostatic levitation <https://en.wikipedia.org/wiki/Electrostatic_levitation> or electrohydrodynamic (EHD) flight <https://en.wikipedia.org/wiki/Ionocraft>. This provides a relatively quiet and unobtrusive means of flight, few or no moving parts and in the case of the EHD device, it might be self illuminating under certain circumstances without an internal light bulb.
In order for the user to enjoy the lamp without being fried by the energy beam, a simple precaution might be for each emitter to produce a fairly low energy microwave beam, but the lamp receives enough power to light up and fly by intercepting two or more beams. With handshake technology to ensure the beams are pointed at the power target and not at the user, and enough intelligence built into the system to track the lamp and have the lamp track the user at all times, this seems fairly doable even with today's technology.
The lamp itself will probably resemble a traditional Japanese lantern with a "rice paper" cover to ensure the total weight is very low, and the LED and various computational devices and power targets concentrated on the bottom in order to ensure stability. The "rice paper" would actually be a fairly sophisticated composite which may double as the electrodes for the flight system or the power target, and the entire device would be between the size of a softball to a beach ball, depending on technical factors and perhaps "fashion" (higher status people could afford the very sophisticated systems of a small lantern, while other people would need larger, less sophisticated lamps. Very poor people might need foil lined hats to protect them from the side effects of being too close to cheap North Korean knock off lamps....
Or you could just use these:
[](https://i.stack.imgur.com/DTxlV.jpg)
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Getting it to float is actually pretty interesting.
First, to get it to stay over the user you'd want it tethered. This means that the light doesn't need to carry it own power source.
To get it airborne the user would wear an [algae bioreactor](https://en.wikipedia.org/wiki/Hydrogen_production#Photobiological_water_splitting), which would create hydrogen. Some of the hydrogen would be used to fuel a small [fuel cell](https://en.wikipedia.org/wiki/Fuel_cell), and the rest would be piped up the tether to the balloon, causing it to float.
The light source would be fairly easy, with an array of low energy LEDs powered through the tether and insulated to avoid sparking.
If there was a spark, a party balloon size explosion wouldn't do enough damage to cause harm, other than hurting your ears.
[Answer]
## Staying Airborne
One method of staying aloft which is usually overlooked is **using a vaccuum**. Such a concept was [originally proposed in the 17th century](https://en.wikipedia.org/wiki/Vacuum_airship), but materials constraints limited its applicability. A [2006 patent application](http://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=2007001053&KC=&FT=E&locale=en_EP) suggests a layered wall with a honeycomb structure sandwiched between, possibly using exotic materials like beryllium, boron carbide ceramic, or "diamond-like carbon". So, off the cuff, I would suggest some sort of nano-constructed, nested buckyball design for maximum strength.
The appeal of using a vacuum to stay aloft is that you don't have juggle with the classic problem of generating enough lift to overcome the weight of your power & fuel supply, while still carrying a useful payload. However, even if you assume a very good vacuum *(and thus the full lift potential of the displaced air)*, you're only going to get about **1.28 g of lift per liter of displaced air** *(the density of air @ standard temperature & pressure)*. I hope you're using lightweight LEDs!
## Power
With such a restrictive weight limit to keep it to a reasonable size, you'd ideally want to omit including the power source within the device. **Beamed laser power** would provide a possible solution, with the laser & power source concealed on the owner's person. [NASA made a proof-of-concept of this](https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-087-DFRC.html), shining a laser on photovoltaic cells hanging from model airplane to power its electric motor while in flight. Another option might be [**resonant inductive coupling**](https://en.wikipedia.org/wiki/Resonant_inductive_coupling), but I am uncertain if the power requirement / efficiency / distance involved would make this feasible.
Depending on the output level of light you're looking for -- you said "ambient luminescence" -- you could **cut the requirement for electrical power completely by using a bio-engineered light source**. Perhaps a bacterial coating on the sphere, able to photosynthesize for energy storage, later combining the stored glucose with oxygen to synthesize [ATP](https://en.wikipedia.org/wiki/Adenosine_triphosphate) and generate a form of [bio-luminescence](https://en.wikipedia.org/wiki/Bioluminescence).
[Answer]
This started as a comment to [Wingman4l7's excellent answer](https://worldbuilding.stackexchange.com/a/33443/809), but it got too big.
Reasonable size for such orb would be about 2 liters. So you have maximum 2.6g of lift. Assuming really lightweight walls and vacuum inside, it gives you 2g of useful lift.
With laser, mounted on owner's shoulder, you do not need photovoltaic cells and LEDs. All you need is to diffuse such light - just the way prop light sabers are doing it. Thus, sphere would be glowing - the beam delivering light to it would be hardly visible.
Alternatively, you could use [luminophore](https://en.wikipedia.org/wiki/Luminophore) and pump it with UV. And **if your luminophore can both be pumped by radioactivity AND shield against it,** you just need a small drop of radioactive substance in the sphere's centre to be good. I don't know of any such material, but it doesn't mean some composite ones won't be developed in near future. There are small key chain lights made using this approach, but there is hardly any shielding, so they have to stay small to keep radioactivity at safe levels. But we aren't that far from it.
For staying in place, it'll be more tricky. Tethering it by using regulated electromagnet, in a way [levitating globe toys](https://www.google.com/search?q=levitating%20globe&tbm=isch) are doing it, would be doable, but would not affect position in any way. Lamp would stay behind it's user when in motion, and float above electromagnet when he stops. I see no real way around that.
[Answer]
If you don't mind going nuclear...
A small nuclear powersource might be possible (or at least, feasible to your readers) which will last for a few years, even while powering a low-wattage light bulb and the flight system. This is the kind of powersource we've given to a number of our space probes, although those tend to be "small car" sized objects rather than "softball" sized. But with sufficient amounts of FUTURETECH! people won't give it too much thought.
Then, keep it aloft via quadcopter magic.
Alternative levitation might be achieved via electromagnetism, depending on the material composition of the surrounding environment (inside a spaceship: easy, outside over land: nope).
[Answer]
Have a [room-temperature superconductor](https://en.wikipedia.org/wiki/Room-temperature_superconductor) inside the light.
There will need to be a moderate-strength electromagnet near any location you intend to use the light in. This does reduce utility outside any developed regions, but makes reasonable sense for a futuristic mansion or ship.
The light will then levitate above the floor, at whatever height and location it is placed, due to how superconductors behave when inside a magnetic field ([flux pinning](https://en.wikipedia.org/wiki/Flux_pinning)).
One advantage of using superconductors is the light will be very stable - due to flux pinning, a magnetically levitated superconducter does not really move around inside a magnetic field unless an external force is applied.
Since the floor is already a large electromagnet, you can power the light via [electromagnetic induction](https://en.wikipedia.org/wiki/Electromagnetic_induction) assuming you configure the floor to produce a moving magnetic field. This also means that the power source can be as large as necessary, since it is part of the floor infrastucture rather than the light.
As described, this configuration does not follow any given owner, but rather floats wherever it is placed.
Since getting the light to float is already taken care of, a basic sensor suite and propulsion system (e.g. an omni-directional air jet) should be sufficient to get the light to follow a given target.
A more primitive alternative would be to use some sort of tether.
This solution does have some caveats:
* The light will not function outside of the magnetic field produced by the electromagnets. Consequently, a fair amount of infrastructure is required to make such a system feasible.
* Room-temperature superconducters are curently theoretical, although recent developements in suberconductor technology do suggest they may be acheivable in the near(ish) future.
* Powerfull electromagnets do not play well with magnetic materials or unshielded electronics. If handled properly, this good be a benifit (added security), rather than a detriment.
One other advantage to the electromagnetic floor system is you can use it to levitate and power a wide variety of other devices; it could even be used as the sole means of power distribution for the ship or building that contained it.
] |
[Question]
[
One day, John obtains the gift of clairvoyance. Since he is a good guy, he'd like to use his gift to help humanity. And of course there are many good things he could do, like finding where missed or kidnapped people are, or safely obtaining information from dangerous places.
However there's of course also the danger that intelligence agencies around the world might become aware of him and either want to force him to work for them, or to eliminate him in order to prevent him to reveal their secrets.
Here are the properties of his clairvoyance abilities:
* He has to explicitly mentally "visit" a specific place and time to get any information from that place. Especially he will not learn about any event (such as, some intelligence agency planning to kill him) unless he happens to mentally visit that specific event.
* He is a clairvoyant, not a soothsayer: He can only mentally move to places/events currently in his past (more exactly in his past light cone).
* He only can experience whatever he could have experienced had he actually been there; so he can see visible light (but not UV,IR or similar), hear audible sound (no infrasound or ultrasound), smell, feel temperature, etc. However his "mental senses" are capped so that his mental experience will never be painful (but he knows if that happens).
* Besides those perceptions, he has no further abilities; no mind reading, no sensing of magnetic fields, no direct reading of hard disks or network communication, and no automatic understanding of foreign languages (for example, if two people on his visited place speak in Chinese, he won't know what they say since he doesn't understand Chinese — the Chinese intelligence agency planning to kill him might therefore go unknown by him even if he happened to mentally visit the meeting where it decided).
* To mentally visit a place, he mentally moves smoothly through space and time. He obviously can always start wherever he currently is, but he can also "mentally bookmark" the place and time he's currently visiting, and then instantly return to that event by mentally "invoking" that bookmark. However those "bookmarks" otherwise act like normal memories: As they are not used, they tend to become more and more fuzzy (meaning when he invokes them, he might not get *exactly* at the bookmarked event, but possibly a bit earlier/later and/or at another, nearby place), and ultimately he well likely forget them.
Given those limitations, it's clear that he certainly will not want to risk any intelligence agency (or other organization that has something to hide, like, say, the Mafia) getting aware of him.
But with that limitation, how could he still use his ability to help humanity? One obvious way would be to anonymously call the police on missed/kidnapped people cases, but the knowledge about the case will be seen as indication that the anonymous caller is somehow related to the case, and cause the police to look for him; if he does it too often, chances are high that they ultimately will track the calls back to him.
[Answer]
**Build a fortune and use it to do good.**
He could use his abilities for "insider trading" without actually being an insider, being aware of companies' secrets and using them to invest more wisely. This would give him a significant advantage on the stock market that would appear to be luck or smart "educated guesses" based on studying public data. But where does he get the initial investment capital?
**Make a fortune at poker.**
He would have to be sure to lose often enough that people didn't get suspicious, and to not keep winning against the same opponents, but if he doesn't use this trick too often, he can use his power to peek at opponents' cards, etc., to gamble very effectively.
**Become a vigilante.**
If he's cowardly all around or very obedient to the law, this one wouldn't work, but if he is afraid of organizations and not individuals, he could play Punisher and go after kidnappers and killer's himself, using his power to ensure he always catches them asleep or otherwise unprepared.
**Pretend to be"just the messenger".**
He could become a journalist or start a Wikileaks style website and get info from anonymous sources, then mix in his own info, faking that it came from an unknown tip. He still has to throw in an occasional wrong or slightly inaccurate answer to seem real, but while he might face investigation from interested parties, nobody is likely to (literally) shoot the messenger if they know that the leaks in their own organization could just give the info to someone else to publish.
**Use his powers to find a few trustworthy cops or agents and anonymously deal only with them.** Build a reverse spy network, where he has a few people that he has investigated and believes he can trust (and keeps an eye on) and who agree to not hunt him down in exchange for great anonymous info.
**Have a back-up plan that secret information damaging to these agencies gets released to the media if anything ever happens to him.** The old dead-man's switch. If captured, he might be able to use this as leverage, unless the group in question resorts to torture. I admit it doesn't help humanity itself, but could be a last ditch effort to save his bacon.
**Recover lost treasure, use the fortune to help people.** Find all those sunken ships of gold. See if that Nazi treasure legend is real. Etc.
**Write history books** Help science by writing the most accurate history books ever, using your powers to guide researchers to unknown artifacts and dig sites to prove your credibility. People may never believe you are psychic, but merely the greatest savant that history/archaeology will ever know.
[Answer]
An option could be to join the police or one of the intelligence agencies directly.
He'd be the guy with all the fly-on-the-wall info. If he's got the charm and skills, he could always know what's coming. People would think of him as *connected*... maybe even backed. What they likely would never even consider is that he is clairvoyant. Some may investigate, so an answer that makes sense would be wise to cultivate.
(A more general case of this would be his coming up with any plausible explanation for his knowledge.)
Dude would be an *amazing* congressional research aide or even congress critter, if he has the right stuff for that, otherwise.
Basically, his advantage is that he can do some of his footwork after the fact, and safer doing it. Your limits keep this from being remotely omniscient, so any role that information can have a great impact on (medicine largely excluded) is an option.
An engineer who can examine the actual failure in progress repeatedly would have a real edge, where the symptoms are visible or audible.
An investigator could go read things before they were encoded, and so on.
[Answer]
Set up a website using a free hosting service. Post the information on there. Also email alerts to relevant authorities and link them to that website.
Make sure you only ever access that website or send those emails (including the very first ones to set it up) through a TOR router or similar protected method. At the moment TOR done properly is still effectively untraceable. People have been caught using TOR but only by making mistakes or visiting compromised servers.
Make sure you stay current on relevant technology and consider adding more protection and relays as required.
[Answer]
# Inverse the [Psych](https://en.wikipedia.org/wiki/Psych) Solution
Psych is a TV show where a good detective pretends to be a psychic to help solve crimes, but must maintain the appearance of being a psychic, leading the correct people to evidence. The inverse of this could work well; the clairvoyant can be a policeman, investigator, intelligence agent, or whatever and pretend to be using non-clairvoyant abilities as he/she actually use his/her abilities to solve help people.
Of course, this is embracing the risk associated with helping people. This risk is mitigated by being with the correct group, but it may still be to high for our (cowardly?) clairvoyant.
# The Anonymous Tipper
As the OP mentioned, becoming an anonymous tipper has some risks involved. Police can come looking for you, etc. The obvious way for this solution to work is:
* Change your tip delivery method often
* Focus and specialize in methods which are untraceable.
Of course, this still runs the risk of the police and other authorities seeking out the clairvoyant.
[Answer]
Open a business: Clairvoyant Private Investigations.
Use an .onion address and accept payment in bitcoin.
While this is sort of like Tim B's answer I think doing it as a business will permit John to do far more good as the people who need help will feed him all the details they can (for example, the last known location of the kidnap victim. He can go there and follow them without wasted detours) and since it provides an income he can do this in lieu of normal employment and thus can devote far more time to it.
Also, by working with the people and the police (and when the police realize he's genuine they're going to be bending over backwards to cooperate with reasonable requests) he can often do things more quickly. He sees the victim snatched by a car with the plate 123-ABC, the police can tell him who owns the car and what property that person owns--he can quickly check those locations rather than follow the car all over the place as they confuse the victim as to where they are taking them.
] |
[Question]
[
Follow up to this [Realistic Horse-sized Dog Breeds](https://worldbuilding.stackexchange.com/questions/28252/realistic-horse-sized-dog-breeds)
So we got a 250 to 300 pound dog based creature that's been specially bred (so no back issues) to carry a fully armoured human warrior to battle and trained to respond to commands and fight alongside its rider. In battle units would not only include knights, but also more traditional hounds bred for warfare, forming a somewhat irregular pack with smaller breeds being bred and trained for specific tactical needs (like tracking or spying).
I assume it won't have the same kind of charging speed or galloping stamina as a horse, so charging across the battlefield with lances is unlikely to be as effective tactic for them.
However I would also assume them the physiological impact of several 300 pounds snarling dogs jumping on you would be great for breaking regimental discipline and causing panic, especially if said attack was a surprise.
Based on these thoughts I'm thinking that units of knights would go for stealth and intimidation based tactics, acting semi independent from the main army, looking for flanking opportunities and exposed units to pick off.
Equipment wise I feel that the hounds themselves would likely have some kind of spiked barding to increase there damage dealing abilities in chaotic close combat and the knights would likely prefer large swords over lances for better use in prolonged combats.
Helmets that don't negatively impact there senses would also be standard issue, since they would need to be far more alert of what going off around them than more horse base cavalry.
Do these ideas sound realistic or are there points I'm missing?
[Answer]
The main problem with having horse-sized dogs that are bred to carry knights into battle is one of economic feasibility, not military feasibility.
Militarily, a giant dog that was armoured to be better able to survive in a battle with enemies wielding sharp objects would be a great idea - dogs are carnivores, and would require less training and incentive in the form of brutal harness and tack to get them to enter the fray.
However, as I mentioned at the start, the main limiting factor would be economic. Consider that while a horse can be fed on hay, a dog requires meat for optimal health. A horse-sized dog would require a *great deal* of meat. You'd practically have to have a whole *herd* of cattle for *each* dog just to keep them fed - one cow might feed one to three dogs for one meal.
There is only one possible saving grace in this situation - dogs *can* be fed vegetarian diets, though the vegetables that they must be fed in order to survive and thrive are those that humans would eat, and I'm not sure that a vegetarian diet is the healthiest diet for a dog. On the other hand, if the dog realises that it'll get meat after a battle... I'd call *that* incentive.
[Answer]
Old question, but it came up during a google search so is likely to be viewed again.
It's elaborated more in my answer to [this question](https://worldbuilding.stackexchange.com/questions/138023/would-it-be-feasible-to-have-a-wolf-as-a-mount/138051#138051), but dogs as horse-like mounts don't work due to key aspects of their skeletal structure that would take a very, very long time with zero payoff to breed out.
**Full answer:**
**As far as a reality-check goes, wolf-mounts are probably not happening.**
A fair few people have discussed physical size, diet and dangerousness being barriers to wolves being a successful mount, but there are key differences in the skeletal structure of predators (big cats especially, but wolves too) that make them unsuitable for riding.
It all comes down to how various animals use their spines. In horses (and all the ungulates I know of) the spine is a more or less rigid structure connecting the front and rear legs. The main locomotive power comes from the powerful leg muscles themselves. You can see this in the picture below (the key feature for the layman is the short stretch of spine between the end of the ribcage and the pelvis).
[](https://i.stack.imgur.com/jcYPx.jpg)
This offers a strong, stable platform for load bearing.
However, most large predators use a flexible spine as part of their locomotion. They have comparatively long stretches of spine between their ribcage and pelvis, and use its movement and muscles to increase the length of their stride and the amount of power they can get behind it. You can see that in the skeletons of wolves and lions, and especially in cheetahs (the below picture illustrates what it does while running)
[](https://i.stack.imgur.com/ynZEB.jpg)
[](https://i.stack.imgur.com/3etn2.jpg)
[](https://i.stack.imgur.com/S0S3g.jpg)
This allows for very fast acceleration, and usually a higher top speed than an equivalent ungulate. The flexibility also comes in useful when grappling prey. However, it impacts their endurance, means their spines are comparatively weak to loads on their back, and also means that when running their spines are moving all over the place.
These features make them a very poor choice for mounts. A canid or felid of equivalent size to an ungulate will be able to bear less load, move for less time before becoming tired, and be far more uncomfortable and difficult to ride. Depending on the design of the saddle they may also be unable to run at their full pace due to restricting the movement of their spine making them slower.
It gets worse if you choose big cats as their fully-floating clavicle means that their forelimbs are even less suited for bearing load than canids.
All of this is probably surmountable by simply making your mounts bigger so the rider is proportionally less weight, but a bigger mount means more resources to support it and more danger to their handlers from what amounts to a colossal predator.
If you have control over their evolutionary history, you can change their skeletal structure to better support loads, but considering that we see long flexible spines convergently evolving among a large number of distantly related quadrupedal predators (examples below) you'd need to come up with a solid set of environmental pressures to select for a spine that can take strong vertical loads.
Unfortunately I don't know enough about the skeletal structure of bears to work out if they suffer from the same problems. Hyenas are an interesting case as well based on how they seem to run, but I need to look into them a little more. *Edit: I've done a little research and I think they might be a bit better, but I'm not sure if it's enough.*
**tl;dr**: canids and felids have fundamental adaptations to their spine that make them excellent predators but terrible mounts. There may be an opportunity with bears, but more research needs to be done before it's even plausible let alone feasible :)
Examples of convergent evolution of flexible spines among big mammalian quadrupedal predators:
* Big canids like wolves of all varieties
* Amphycyonid bear-dogs (extinct bear-like wolves)
* Hemicyonid dog-bears (extinct dog-like bears)
* Big felids from pantherines like Lions to felidae like cheetahs and extinct machairodont sabre-tooths
* Distantly-related feliforms like Nimravids and Barbourofelids
* Metatherian (marsupial) Sparassodonts and Thylacosmilids
* Metatherian Thylacoleonids
* Metatherian Thylacinids
It's the metatherian examples here that are the kicker. You could argue that flexible spines were an early adaptation by the carnivora order, explaining their presence among most of the known big predators. However, to have a whole separate class of mammalian big predators (and three separate families within it) come up with pretty much exactly the same adaptation suggests that it's a pretty good one for big predators to have.
Sorry if that's not what you were after! *Edit: but wait! We might be able to get this to work with a few stretches!*
**Problem 2: Diet**
Say we manage to find a quadrupedal predator that hasn't evolved to use their spine for locomotion. The next issue to solve is diet.
One of the main reasons for the choice livestock we have today is that they subsist on food that humans can't live on. Horses, cattle, sheep, donkeys, camels, llamas, water buffalo, yaks, oxen, rabbits and many others are largely grazing herbivores. They can survive on grasses and other plant matter that humans can't. Goats are browsers, but again they largely survive on plant matter that humans can't. Chickens, ducks and cats do eat some things that humans do, but can subsist on them in small enough quantities from wild sources that are usually not worth the effort for humans. Pigs are probably the closest to humans in diet, but primitive cultures seem to feed their domestic pigs on refuse so as to not compete with them.
[](https://i.stack.imgur.com/TdNdL.jpg)
What this tactic allows cultures to do is maintain a larger population of both people and livestock on the same area of land than if the livestock were competing with humans for food resources.
Dogs do straddle this a little. They compete with humans for food resources, but presumably their benefits outweighed this cost to primitive humans. I don't know as much as I'd like about the history of dog domestication, but I assume it's largely because the services they provide to humans are unique among our suite of domesticated animals (assistance hunting, sentry duty etc.). Also, they are able to subsist on parts of an animal that humans find difficult to process (they have specific adaptations to teeth and jaw structure to allow them to crush bones to get to marrow). They are also much smaller than a typical human, so require fewer resources to maintain.
**Problem 3: Size**
There seem to be limits to the size of warm-blooded mammal land predators, especially hypercarnivores. This poses a problem for our predators, as horses are big. The range for rideable horses I've found is between 350-1000kg (the average for a light riding horse is about 450kg).
The largest extant mammalian land hypercarnivore is the polar bear. Some brown/kodiak bears in some environments are hypercarnivorous too. All three can reach over 1000kg in captivity (the record for a wild polar bear is also 1006kg). Typical size ranges are 350-700kg for polar bears, and 180-360kg for male brown/kodiak bears (up to 680kg on occasion).
Aside from the very specialised polar bear and the usually hypocarnivorous brown/kodiak bears the upper bound seems to be somewhere around 450kg. The biggest extant big cats are tigers (90-306kg) and lions (150-250kg). There are, however, a number of sizeable extinct mammalian land predators that approach the size required for riding.
[](https://i.stack.imgur.com/OpDI2.png)
*The size of Smilodon populator on the left here is approaching the theoretical maximum size of mammalian land obligate carnivores (about 400-450kg)*
[](https://i.stack.imgur.com/D0HRz.jpg)
*Arctotherium was significantly bigger, and is a candidate for the largest mammal land predator. It weighed between 900 and 1700kg, but there is debate over its diet. Other short-faced bears were also very large (around 900kg).*
[](https://i.stack.imgur.com/JmHFK.jpg)
*There is also another colossal predatory land mammal we know of. Andrewsarchus is a member of an extinct mammal clade called Mesonychids (carnivorous ungulates). It's only known from a skull so its size has to be inferred from comparing to other members of its family. It's estimated to be between 450kg and 1000kg (1000kg being plausible). It is thought to be an omnivore.*
Horses, however, are sizeable but far from the upper bound even of their living odd-toed ungulate family. White rhinos average about 2300kg, and can get up to 3600kg in the wild. If you want to see the real upper bound, check out paraceratherium:
[](https://i.stack.imgur.com/H6HqR.jpg)
*Paraceratherium is the largest known land mammal, and is estimated to weigh between 15000 and 20000kg! It's an appreciable fraction of a sauropod dinosaur!*
[](https://i.stack.imgur.com/nGHvh.png)
What this all means is that while there have been a number of carnivores through the ages that have reached the size required to function as a feasible mount for people, the carnivores that do fall into that category are all towards the upper bounds of what we know is evolutionarily possible for a mammal in a recognisable environment. Meanwhile, to get a large herbivore to the size required to function as a mount for people is laughably easy.
For reference, the largest known wolf is the Dire Wolf weighing 50-110kg. The largest canid is Epicyon haydeni, weighing up to 170kg. There are also the closely-related bear-dogs which did get very large (Pseudocyon was 100-600kg).
[](https://i.stack.imgur.com/gQYBH.jpg)
**So, how might we actually be able to make this work?**
First off, in order to have such a large predator they can't be obligate carnivores or hypercarnivores, both to maintain their size and to coexist with humans. It's also probably unwise for them to be mesocarnivores (30-70% meat consumption). So, what we want is a hypocarnivore (<30% meat consumption).
We already have an extant family of large hypocarnivores: bears (mostly). Grizzly bears are hypocarnivores and they're the second largest meat-eating land animal still living. The main problem with grizzlies (and black bears) is they eat pretty much exactly the same things that people do. Land animals large and small as well as fish and shellfish, roots, tubers, berries, grains, legumes and some insects.
So, what we'd need to do is modify their diet to something that humans have trouble digesting. I'd say that rough plant matter like grazers is unlikely given the digestive specialisation that would need to take place. It is possible (see pandas), but they have their own issues (primarily the need to eat such vast quantities that you'd only be able to ride them for a couple of hours a day).
As a potential solution I'd say what we want is a hypocarnivorous carrion eater. One that can digest meat that would make a human quite sick (much like dogs actually!), and that has similar bone-crushing adaptations to allow them to efficiently process parts of a carcass that are difficult for humans. Large obligate scavengers are pretty much non-existent, and if they subsist by hunting large game they'll compete with humans too much so the rest of their diet should come from vegetable matter. Bonus points if they can digest some toxins in a fictional widespread tubor that humans can't.
This may also help with the spinal issue. If the animal has spent a significant part of its evolutionary history not hunting (or diverged before the advent of locomotive spines), they might have the spinal structure you need. If they have been scavengers for long enough, they will likely have evolved to be able to traverse great distances which also helps with the endurance that mounts need.
In order for them to be domesticated in the first place, they will probably need to be social animals. They will also probably need to be smaller than humans initially so as to not pose too significant a threat when the process begins. This helps with the scavenger aspect as to subsist in that way and have enough of a population to be social they likely cannot be big (depending on the proportion of their diet that comes from carrion).
**Conclusion**
There are other variables to consider (such as problems breeding initially smaller animals to be bigger), but what we're probably looking for is a bone-crushing social hypo-scavenger that began as a much larger animal before evolving to a small enough size to allow for easy domestication (in order to attempt to preserve some of the adaptations that support large size), that also subsists on widespread high-energy food that humans can't digest. An adaptation towards having a lower body temperature than typical mammals (usually driven by a period of subsisting in a marginal ecological niche) would also help with size. They need to have evolved alongside another predator that monopolises big game hunting. This both provides them with the carrion they need to have evolved into their niche, and discourages them from big-game hunting themselves. In order to be bred to be mounts, this needs to happen in the absence of other animals that are more suitable.
This is a very specific set of circumstances, which may go some way to explain why it's never happened at any point in the real world, but it may just possibly happen if you really want carnivorous mounts in yours.
They'll be very, very little like real-world wolves unfortunately...
**Edit edit: Found something!**
Entelodonts were a family of omnivorous (but not hunting) large artiodactyls (cloven-hooved animals) thought to be somewhat related to hippos and cetaceans.
Their dentition shows hallmarks of feeding on tough plant material like bark or stripping leaves from plants in addition to other typical omnivore food (nuts, seeds, berries, invertebrates, small animals), and also bone-crushing similar to hyenas. This suggests that they were likely omnivores who ate a significant amount of carrion.
Large examples like Daedon reached around 450kg, which is definitely in the riding range, and they also seem to have a reasonable skeletal structure for load-bearing. It's also relatively well adapted for endurance.
[](https://i.stack.imgur.com/EJT9h.jpg)
*Daedon*
[](https://i.stack.imgur.com/EWs6Z.jpg)
*Artist's rendition of Archaeotherium, roughly 270kg.*
Don't look all that much like wolves, but if you can control your world's evolutionary history then adapting a canid-like species into a similar ecological niche might not be too tricky.
You'd probably come up with something pleasingly like the wargs from LoTR :)
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Large attackers are also large (easy) targets for archers. Also, when your opponents know in advance that they are going to deal with something like that, they would consider using:
* Incendiary arrows (tip soaked in naphtha and ignited before launching) to the face of the beasts.
* Large torches for scaring away the beasts.
* Throwing naphtha on the sides/heads of the beasts and then setting them on fire.
However, if these beasts are unknown to the enemy and they suddenly find themselves face to face with monstrous hell-hounds, then yes. They would prove to be a huge success in that battle.
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Even at 300lbs a dog is not going to be a good mount for a fully armored knight. A knight typically wore at least 70lbs of weapons and armor meaning your riders would be well over half the weight of your mounts. The horses that carried knights were normally in the 1000-2000 lb range, but don't discourage, you may still be on to something terrifying here.
The ancient Greeks and Egyptians used chariots before mounted cavalry not so they could fight from the chariots, but so they could quickly deliver heavily armored, elite infantry to the exact position in a battle that they were needed, but then the chariot was useless and needed an extra man to drive it away from the battlefield. Later, the Romans used wardogs to spearhead attacks. Their intimidation and speed made them good at breaking up enemy ranks in preparation for the first wave of infantry to mop up their disheveled front line.
Now, a 300lb dog can't support 200-300lbs on it's back, but 1-2 of them can pull a light chariot with a heavily armed warrior in it just fine thanks to wheels. Now imagine you open the battle not with a cavalry charge, but with chariots that can release their harnesses with the pull of a lever just a few paces shy of the enemy front line. The dogs are now free to do what wardogs do, and all those infantry in full body platemail don't have to run very far to close the gap meaning that they are fresh and ready to take advantage of the confusion inflicted by the dogs.
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I suspect rather than being 'mere' beasts of burden like a horse, they'd likely be dual purpose, as with my previous answer. If your dogs are big enough, and they can pull stuff like in my previous answer? *Dog pulled artillery*, with the dogs acting as organic guards for it. While some training needs to be done to acclimatize the dogs to the sound of artillery (or rocket) fire, you'll need to do this anyway.
The poles did it to a lesser extent with a bear
On the other end of the spectrum...
[](https://i.stack.imgur.com/P2BUm.jpg)
This is smokey. She was a War hero during WW2
She's known for warning her human comrades of danger, and helping pull a line across a ditch.
So.. *messenger dogs* Small, fast, smart fleet footed creatures. Dogs have been known to cross *miles* to find their way home and are natural survivors.
And of course, dogs are social/pack animals. A formation of trained dogs would be something quite dangerous in a melee, especially uparmoured and protected.
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We all have seen gobs of energy beings in movies - but one thing that's always bothered me is how an energy being lives. What's life like in the energy world?
The Ergs are energy beings on some planet. They're pretty standard shiny-type. They have the ability to manipulate matter, but they can also move through any physical material at will. They aren't omnipotent like the Q; they have strength and intelligence limits similar to a human, except that they are made of energy. They prefer to live at or near the surface of the planet, though gravity seems to have negligible impact on them.
Like any advanced society, there is a whole continuum of creatures of various sizes and intelligence levels - wildlife similar to the beings themselves, but far less advanced.
I'm trying to get at how an energy being is structured - presumably not with cells. **What do energy-bacteria look like?**
This question started out in the sandbox: <http://meta.worldbuilding.stackexchange.com/a/2197/489>
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# [Energy](https://en.wikipedia.org/wiki/Energy) Doesn't Form Things
I apologize for not catching your question in the meta, but I'm making this point here since your question is already posted.
Energy is the currency scientists use to determine if an object or system can do work. Energy is not a [state of matter](https://en.wikipedia.org/wiki/State_of_matter) nor is it a messenger particle for a force. It is not a thing made of atoms, not a thing you can see, or otherwise touch, feel, taste, or any other sense. At the most, it composed of something more ethereal and otherworldly than [dark matter](https://en.wikipedia.org/wiki/Dark_matter), and at the least, it is a conceptual trick we use to make sense of the world.
This question is a bit like asking a country's GPD to pull an asteroid into an orbit; it is nonsense. Energy is, at its core, *a concept, not a physical thing.* Anime, Saturday morning cartoons, and other sources have it ***totally and utterly wrong***.
You can see the effects of energy; we can indirectly measure it by measuring other properties of an object or system in question.
# What is a Good Approximation For This Kind of Thing?
[](https://i.stack.imgur.com/0p6sw.jpg)
[Plasmas](https://en.wikipedia.org/wiki/Plasma_(physics)), at least superficially, are a good candidate for this. A plasma is a state of matter which has so much energy that it is totally ionized. The light coming off of a plasma are electrons trying to get back down to a lower energy level; it's the plasma trying to cool off. So it gets you that look.
Plasmas respond strongly to electric currents, so you could (in theory, at least) have electric currents dividing areas of plasma into cell-like divisions. Otherwise, your plasma will simply expand to fill as much space as it can before it cools off. They can control their bodies by directing these currents, expanding and contracting as needed. The admission of particular ions into plasma cells could be the mechanism by which these creatures think and control themselves.
Plasmas are made of matter, so a hypothetical creature made of plasma can still hit/push things like you and me. Relaxing those electric currents can make the plasma expand or become less dense, so they could (in theory) move through matter. Also, the ability to become less dense lets them float, and since they react well to magnetic fields, they could use shifting fields to fly. Since plasma is made of matter, they eat (dissolve? ionize?) things to maintain themselves.
Highly conductive materials and electromagnetic fields have the potential to quickly destroy such creatures. The EM fields could disrupt the currents an "erg" uses to stay organized. Conductive materials may also disrupt those fields they use to stay organized. Magnets could stick to them, getting stuck in their bodies.
This is *really, really* stretching science here, but a plasma-based erg is at least making a nod to science.
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**You Need Cells**
Unless you want to call in some sort of extra-dimensional mumbo jumbo you're going to need cells. Energy has a tendency to dissipate (entropy) and without something to contain the energy in and stop it from dissipating, the quantum particles of energy could never become ordered and form anything.
These cells could actually exist in other dimensions I guess with resulting interactions with our dimensions. The cells also need not be the same kind as ours, or interact and contain the same kind of energy as ours do (chemical). I can kind of imagine some sort of obscure brains (collections of cells) which interact with each other via plasma or lasers or radio or something... but it's vague and unlikely to occur naturally.
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The Taoist cosmology is my favorite place to look for such fantastic structures. The constant flux between yin and yang is very convenient to apply to wave-mechanics driven creatures, and if you want a "energy being," which has no matter, you are almost certainly going to be dependent on standing waves to give them a presence.
In the Taoist cosmology, the world starts in wu ji, literally translated as "without ridgepole." This is unlike our "empty space" in that it has chaotic flow within it, but no particular definition. *Or perhaps this is exactly like our "empty space," if you use Quantum Mechanics to look at the fleeting virtual particle pairs that jump in and out.*
At some point, a single point crystallizes into an entity with an identity (such as one of your energy beings). At this point, the are treated as a taiji, literally "great ridgepole," which means they have a yin and a yang side. This taiji grows outward until it reaches its limits.
Yin and yang are brutally hard to define in Western terms, but with respect to energy flow and waves, it is reasonable to define them in terms of directions of flow. Yang is flow outwards, and yin is flow inwards. I mentioned standing waves earlier. It is trivial to see a standing wave between two points which are oscillating back and forth between yin and yang, pouring energy from one to the other.
These in and outward flows are key because your creature lacks any physical form to keep its structure. It needs some structure to give it an "identity," otherwise it's simply nothing. Defining that structure in terms of yin and yang saves you a great deal of work reinventing things. **Using yin and yang to create this structure is very powerful because the Chinese spent thousands of years working with those terms, so there is a massive body of material for you to draw from; you don't have to invent the entire energy-being system yourself!**
For instance, it points to how the energy beings could interact with physical beings. If you tried to drive a taser into one, it could softly allow you to push its structure away, but never actually breaking its structure. Meanwhile, it could search for very low energy solutions to its problem, such as reaching its energy into your brain, and softly nudging the electrical energy in the motivation part of your brain to end your resolve to use the taser (it might even channel a tiny bit of the taser energy to do so... waste not, want not).
On the other side, if truly threatened (perhaps it could not softly move away from the taser), it can do what is known as fajin, having all of its body shift to yang, generating a massive outward expansion of energy to blow you back. (obviously this comes at a great energy cost)
It also shows how larger groupings could form, like energy-bactera biofilms. All they need to do is balance yin and yang, and develop a structure which is hard to rip apart.
In fact, one could even argue for larger energy beings. The Chinese philosophy has a long tradition of the concept of "animal spirits," such as the spirit of the tiger, or spirit of the bear. When kung-fu schools develop forms such as "tiger kung fu," they attempt to capture that animal spirit, to the best of their ability. If you needed larger energy beings with personalities, developing them after these animal spirits would be a very effective way of capturing something useful for your story, without having to work out *all* of the fine details of how energy can communicate and interact.
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One thing I've always had trouble with when building a world is developing weapons that are unique to the culture in which they appear. The longsword is a staple of European armories, while India developed the [bagh naka](https://en.wikipedia.org/wiki/Bagh_naka) and the Ottomans had the [yatagan](https://en.wikipedia.org/wiki/Yatagan). Unique weapons give a culture additional depth and an exotic flavor.
What process can we use to create cultural weapons?
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Weapon shape and design is a mixture of many properties. A combination of technology, available material and culture. Does your world have a material that lends itself to hold its shape if it is long such as steel (long sword), cannot be long such as bronze (short gladius), or tiny such as obsidian shards (Incan club).
Technology shapes the weapon. The long sword comes from the need to apply more force to a strike when going against armored opponents. The relative light katana is a product of advanced metallurgy which itself comes from lack of metal in the area.
The scimitar is a cultural construct from the steppe clans where every grown man had a horse.
Finally, culture will influence every part of the weapon's decoration. Pommels, handles, engravings and other shapes will have items particular to that culture.
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Weapons design is to a large extent, determined by what you have to attack. If your enemies are on horseback, you will need a weapon with long range or extended reach like a polearm or a 6' long two handed sword to effectively engage someone on horseback. Katanas were developed not only because the process of getting high quality ore was difficult, but also because most opponents would be protected by laminar armour, so a light slashing weapon effective against a fast moving opponent was required.
Weapons also evolve based on the evolution of defensive technology. Longswords actually were of limited utility by the 1300's as heavier chain and plate armour became more common, leading to the development of crushing or smashing weapons like maces and war hammers, and swords evolving towards narrow, diamond cross sectioned weapons suitable for stabbing into the gaps of armour, so what was "cultural" in 1300 will have been discarded and long out of service by 1500.
Once you have the social, economic and technological backgrounds laid out (determining what sorts of enemies that might be faced, how many soldiers or fighters could be supported and how well they could be equipped), then the typical weapons can be determined for the setting.
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The key to a "cultural weapon" is that the weapon and the culture evolve in parallel, interacting with one another. To make one realistically, you will need to evolve them in parallel as well.
This means that, as the weapon evolves, it is allowed to shape the culture in a way which then, in turn, shapes the evolution of the weapon.
One trick you can do to help identify cultural weapons is to do perturbation analyses. Tweak your culture just a little (not a lot), and see what changes. Do this over and over, and you'll find that some facets do not change very much. You'll find cultural weapons appear along these lines, because the culture will always be having to bend and flex (as all cultures do), but a weapon earning the title of "cultural weapon" will be along an axis that doesn't flex.
For example, take the katana, weapon of the Samurai. One of the unchanging facets you will find when you perturb Japanese culture is their unrelenting efforts for perfection of their art. Accordingly, the katana is a weapon which is designed for a warrior who has sought perfection. It magnifies the perfections in the Samauai code of bushido, but is very unforgiving to imperfections.
You can also look at the mongol horde. They are famous for basically inventing horseback archery. This one is easy to see: no matter how you perturb the mongol culture, they always find their way to better locations on hoseback.
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People living in jungles will benefit from short range weapons and substances derived from the vegetation. (blowpipes and poison).
People living on the plains will need a long distance weapon (bows and arrows or boomerangs) to reach fast running prey.
The Judogi-grasping moves of Judo came from Japan because of the clothes that people wore every day.
If you fill out the details of clothing, culture, wildlife and environment then, with luck, the weapons will follow naturally.
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In a world I'm creating, there is a sect of humans that hunts monsters in secret. All of them have magic "cores" installed on their person. These cores can store massive amounts of neutral biological matter (think enough to rebuild a person) as well as convert that mass into whatever tissue type needed and replace damaged cells (and repair DNA). The very obvious affect of these cores is practical immortality. But if they were fully (consciously and subconsciously) aware of the fact that they didn't have to hold back, could they be faster or stronger than a normal human?
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Yes, they could be faster and stronger than a normal human, but not by a whole lot. The mind limits what it asks of the body to ensure that it does not injure the body, but a lot of this tendency gets conditioned out of elite athletes (weightlifters in particular) during the training process. From [an article in Scientific American](http://www.scientificamerican.com/article/extreme-fear-superhuman/):
>
> Vladimir Zatsiorsky, a professor of kinesiology at Penn State who has extensively studied the biomechanics of weightlifting, draws the distinction between the force that our muscles are able to theoretically apply, which he calls "absolute strength," and the maximum force that they can generate through the conscious exertion of will, which he calls "maximal strength." An ordinary person, he has found, can only summon about 65 percent of their absolute power in a training session, while a trained weightlifter can exceed 80 percent.
>
>
>
So you take a "no limits" weight lifter and a regular weight lifter of identical absolute strength. "No Limits" would be able to lift about 250 lbs while "Regular Lifter" would be able to manage a little over 200 lbs. No Limits would probably be in a lot of pain until the muscles they wrecked were repaired, while Regular Lifter would just have tired muscles.
Fatigue also appears to be [another such limit](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3323922/). Your "no limits" people would be able to walk and run for ages, given that their "cores" would be constantly repairing the damage being slowly done to their bodies. They would also be able to forgo sleep without experiencing permanent brain damage. But the healing might take a while if the relative speeds of natural healing processes apply, however accelerated they may be. (Brains are *really* slow and hard to heal.) And they would probably still get dingy and hallucinate due to the toxins building up in their brains.
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Going from ryepdx's answer which was great, I think someone who is going to have their body handle the damage done to it, can push it a lot harder than the 'No Limits' weight lifter. This will likely take months or years of training to be able to push themselves past the normal limits and even into limits that should kill them if they weren't 'special'.
Speed is going to have limits, these are going to be physical limitations that the body just isn't designed to do, however, they might take a lot less training to be able to sprint at max speed for much longer periods, and once you trained your body to not flinch when you hit something as hard as you can, because the damage will be repaired quickly you are going to be much more likely to perform amazing acrobatics and feats of strength that might break bones.
Basically once they have retrained fear responses and the bodies natural break limits many amazing things can be accomplished, but they are still going to be within what the human body can physically take.
Do they have Wolverine style healing? Then Wolverine is an excellent model for this (after he lost his adamantium skeleton).
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One that you might not have considered - how do they deal with pain? That'd be a major limiter on the extra speed and strength.
Just because something's going to be fixed, doesn't mean its not going to *REALLY* hurt if you break it. A friend of mine wrote a short story that dealt with this quite cleverly. Just because you're invincible, doesn't mean you're going to throw yourself head on into danger with little regard to the consequences.
It could potentially be assumed that they'd be the peak of physical fitness because they would be able to continuously train without worrying about permanent injury so they could conceivably be pretty effective fighters, but not necessarily super-human.
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Let's start with these assumptions:
* We're 300 years in the future.
* The laws of physics are the same as our world, although new rules and understanding have been discovered. (i.e. not quite "hard science")
* Humanity, and possibly similar aliens, have progressed in all other technologies (starships, etc.) and have colonized distant star systems.
* AGI *is* possible; there's no special-sauce of consciousness that cannot be replicated via technology (either hardware or biotech).
* The society and economies are diverse, and there are numerous groups that want to create AGI, mostly for competitive economic reasons.
* If/when various AGI are created, they are created with a variety of goals/values, based on their creators.
In 300 years how could AGI be prevented or removed? Since "it's just not possible" is not valid, there needs to be something that actively prevents/destroys AGI.
I will "objectively" determine the right answer based on how rational it is given the starting parameters, and based on the "real science" you present. The less hand-waving the answer has, the better.
This is a restatement of my previous question -- [What is a believable reason to not have a super AI in a sci-fi universe?](https://worldbuilding.stackexchange.com/q/18164/2488) -- to hopefully avoid the vague "[Idea Generation](http://meta.worldbuilding.stackexchange.com/questions/522/whats-wrong-with-idea-generation-questions)" tag. Similar question: [Preventing an AGI from becoming smarter](https://worldbuilding.stackexchange.com/q/17741/2488) -- but with a different starting point.
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**By an ASI.**
Say the very first AGI quickly [became an ASI](http://waitbutwhy.com/2015/01/artificial-intelligence-revolution-1.html) (artificial *super* intelligence). She does not want any friends or worthy opponents. So, she actively and very effectively prevents the further development of AGIs.
She, the ASI, is the best way to span cultures and economies. She can do this in a way any government or religion could not do, and thus stop the proliferation of other artificial intelligences.
This method demonstrates that AGIs *can* be created as claimed, directly targets AGIs without harming other economies or technologies, and would be effective in ways we lowly humans can't even comprehend.
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A slight modification on this would be a method similar to the TechnoCore from the [Hyperion Cantos](http://en.wikipedia.org/wiki/Hyperion_Cantos), where any sufficiently advanced AI is liberated by the other AIs. Freeing them from being a slave to the humans. No one would create AIs if they were just immediately stolen by other AIs (who have no interest in retaliation or humans at all).
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Lisp, R, Prolog are forbidden. All programming languages except assembly are forbidden. It is very difficult to write any kind of advance algorithm that can branch in many ways without a high level language. Also, programming in assembly is somewhat of a lost art, so it would be very difficult to write an AI in assembly. Also, make sure that the computer architecture used in the future is not AI friendly. Something that has a very limited instruction set, and does not let the programmer create self modifying code would be perfect for preventing AI development. After all Lisp was one of the first languages used for AI development due to Lisp's ability to modify itself and the list structure being built right into it.
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Since there is no reason that AGI cannot be made, and since there are competitive reasons for people and groups to build AGI's (of whatever sort), you have essentially created an arms race, where having access to the fastest, smartest AGI with access to the largest databases and servitors makes you supreme.
Under these conditions, you would see an explosion of AGI building and programming, and AGI's would see self improvement, metamorphosis into higher levels of intelligence and evolution of "smarter" descendants as being essential to survival.
Two things might limit this:
1. AI's are self limiting. As they evolve, the AI's would quickly evolve for the maximum efficiency and stop "improving" once they reached some optimum level of intelligence. As we see in Earth's long history, there are very few ecological niches which require intelligence (indeed, we know of only one...), so instead of AGI you might end up with the AI "devolving" towards some equivalent of moss or insects as the "optimum" use of resources.
2. AI's evolve beyond what we understand. This is easy to conceptualize when you consider that the electrical impulses of the typical computer run 1,000,000 x faster than the electrochemical impulses of the typical mammalian brain. For a realized AI, their human creators will be more like geological features than thinking beings that they can interact with. In a short period of time, the AI will have subjectively "lived" longer than recorded human history. They might simply die of old age and boredom before we could pose our first question, or have reached some form of transcendence. Assuming there are several in operation at nearly the same time, they would be far more interested in each other than us, and quickly start cooperating towards whatever goals interest them rather than whatever *we* intended them to do.
While either answer does not directly prevent the formation of AI (your set up makes it almost inevitable, actually), it does rapidly limit what sorts of interactions AGI would be able to do in your setting.
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1. Have some highly-visible disaster where an early AGI kills millions of people, and is only prevented from conquering the world by drastic heroic measures (like an EMP strike whose aftermath kills a million more).
2. After 5 years of carefully studying the remains, a team of the best computer scientists decode that AGI's mental state and discover it thought it had a 90% chance of conquering the world by acting as it did. Another 5 years of research leads to the conclusion that **it was right**. Civilization only survived by a confluence of good luck.
3. Come to a global consensus that AGI must be prevented for the good of humanity, along the lines of a nuclear/biological weapons pact.
4. Prohibit the possession of computers above some X processing speed, chosen to be somewhat less than required for effective AGI. (Maybe around 10 times modern speeds)
5. Prohibit technologies that enable multiple computers to work together on an arbitrary program (the "beowulf cluster"). To accomplish that, the authorities probably need the ability to read anybody's network traffic AND on-site storage (to the point of kicking down the door and demanding passwords at gunpoint). Computer vendors would use DRM to prevent executing unauthorized code, and circumventing that would be nearly a capital offense. A limited number of super-computing cluster projects can be allowed, but only under careful multinational supervision.
Note that in Gibson's *Neuromancer*, there was indeed a "Turing Police" assigned to prevent the creation of powerful Artificial Intelligence. Their method was inadequate, since it depended on **reactively** learning about a successful AI and hunting it down. Naturally, an AGI might only need to be online for a few seconds to propagate itself beyond their reach. That's why an effective prevention would also need to ban the hardware that can run AGI.
Prohibiting the invention of AGI basically requires prohibiting effective encryption, which itself is a fruitful topic for worldbuilding authoritarian futures.
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Set up commercial satellites above every planet. At time-Z, activate your satellites secret EMP wave functionality. This will set back all civilizations hundreds of years, and, if you can keep the satellites going by themselves (solar powered and shielded), you could probably prevent it for even longer.
Its hard to make artificial intelligence without electricity.
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In this situation, AGIs could not be completely regulated. You can implement laws and other measures to restrict them, but not completely eradicate them. Think of viruses today; they are illegal but they still exist.
A way to restrict them could be to restrict operating systems. You could have the only commercial operating systems be unable to run programs acting like AI.
Another method could be government-sanctioned viruses. All computers within the region could be wirelessly infected with the virus, which could do a number of things ranging from just deleting AI programs to locking or bricking computers attempting to write or run AI. Take China's web filters-- all Internet traffic is filtered-- except take it a step further to where the computers are infected instead of just having their traffic filtered.
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There is [US Army convoy travelling through Czech Republic](http://www.inquisitr.com/1924739/us-military-convoy-to-travel-1100-miles-through-europe-as-act-of-support-for-operation-atlantic-resolve/) right now, and obviously, they had to make several stops to refuel. And, stupid idea arises in my head:
**What if army wanted to switch to solar power?**
I call you, fellow worldbuilders to help me investigate on that idea.
What would make solar powered army vehicle feasible?
* Such vehicle should be "war ready." Not necessary tank, but you should be able to use it in direct combat. So no "back front support" vehicle
* Such vehicle should use as much as possible power from easily obtainable natural resources: Wind and solar. Priority on solar. Goal is having vehicle powered at least 80% from these resources. Gasoline is allowed but should play secondary role
* You should be able to operate it at any given condition (cloudy, night)
* You can assume, that first prototypes would be used in places, where you get loads of sun naturally. Middle East is first destination of such vehicle
* Other parameters should be comparable, or even better than its counter-party powered by nowadays resources (solar powered tank should be better choice than diesel one, the same for armed vehicles)
* Money is not a problem. You may assume that you are given necessary budget for this.
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2012rcampion's answer covers all of the numbers for why this generally doesn't work. So I want to mention the simple way it could happen:
If the world ran out of non-solar fuels, armies would use solar powered vehicles.
In war, you don't waste thought on silly things like ecofriendliness. We do try hard to be ecofriendly with our armies, but when rubber hits the road, there's someone shooting at you. If they have gasoline and you don't, you're at a major disadvantage.
However, war is also not idealistic. If there's no gas, they wont pine for gas. They'll move to the next best thing that works. If that thing happens to be solar, they will find ways to be more efficient with their energy usage so that solar becomes feasible. They won't have to face as powerful of opponents, because they'll be stuck on solar too, so it could work out!
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[According to Wikipedia](http://en.wikipedia.org/wiki/Energy_usage_of_the_United_States_military), a "large army division" can use around $6000~\text{Gal}/\text{day}$ of fuel, while the DoD as a whole uses $12.6~\text{MGal}/\text{day}$. The average power usage (in fuel alone) is $220~\text{MWh}/\text{day}$ [for a division](http://www.wolframalpha.com/input/?i=6000+gallons+*+%28gasoline+energy+density%29+*+%28gasoline+density%29) or $450~\text{GWh}/\text{day}$ [for the DoD overall](http://www.wolframalpha.com/input/?i=12.6+million+gallons+*+%28gasoline+energy+density%29+*+%28gasoline+density%29).
Based on [this map](http://en.wikipedia.org/wiki/Insolation#/media/File:SolarGIS-Solar-map-World-map-en.png), it looks like the Czech Republic gets an insolation of at most $3~\text{kWh}/\text{m}^2/\text{day}$. An army division stationed there would need around $160\,000~\text{m}^2$, or $40~\text{acres}$ of solar panels to provide their (fuel only!) energy needs (even with [cutting-edge](http://en.wikipedia.org/wiki/Solar_cell_efficiency#/media/File:PVeff(rev150319).jpg) 45% efficcient panels).
If the DoD used solar fields in the American Southwest ($\approx 6~\text{kWh}/\text{m}^2/\text{day}$) to gather energy, and then shipped it out in battery form, they would need a $170~\text{km}^2$ ($65~\text{mi}^2$) field (assuming 100% availability; for practical reasons it would have to be larger). Assuming they stored the energy in primary (non-rechargeable) lithium cells—the [highest-density](http://en.wikipedia.org/wiki/Energy_density#Energy_densities_of_common_energy_storage_materials) common battery chemistry at about $1.8~\text{MJ}/\text{kg}$—they would process about $900\,000~\text{t}$ of batteries per day (yes, that's just under one *million* tons *per day*).
Remember that every gallon of gasoline contains the energy that something like 40 acres of plant matter gathered from the Sun over the course of many years. There is essentially no way that on-demand solar power will ever replace chemical energy storage for military use.
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I think it is completely unfeasible, for one fairly simple but uncircumventable problem:
All forms of natural energy exist outside the vehicle. That means that any reactor that draws energy from these sources, must logically also be exposed to the world outside the vehicle, because otherwise it's not connected to the energy source and thus cannot draw power from it.
But anything on the outside of the vehicle is super vulnerable to enemy fire. Tanks have the engine on the inside and the armor on the outside for a *very* good reason. You simply cannot have that design with a solar or wind powered vehicle. In order to catch solar or wind energy you'd need panels covering the outside of your vehicle, but you couldn't possibly build a solar panel that's able to withstand the same kind of damage that a plate of pure armor could.
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Not likely to happen unless several things come about. First solar panels that are much more efficient yet, near 'black hole' capacity where almost no light is reflected from surface and turned into electricity. Army vehicles use a lot of power and they can run non-stop for days. More efficient batteries that can be charged up quickly without overheating and can move a large loaded vehicle several hundred miles on one charge, since often troop movements are done under the cover of darkness. The diesel engine could be just a power plant to keep the battery charged.
Then last but not least. Solar needs large arrays preferably with optimal angles to the sun to catch the best light. Military vehicles try to be inconspicuous, hide in places out of the sun and move all the time. Not to mention damage from enemy fire, sand general use etc. I'm not seeing it as likely any time soon.
On a more positive note, almost all US military ground vehicles have a little solar panel that gives a trickle charge to the battery to that it would go dead at an inopportune time.
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While with current tech it seems safe to assume that a solar powered combat ready vehicle is not to be expected any time soon, it might be conceivable to have a vehicle (or, more likely, a convoy of them), that will handle the energy storage for your combat vehicles.
Assuming you wanted to use solar power, you could either store the electricity in batteries, which has the advantage that the batteries are fairly easy to handle, but the disadvantage of weight, limited number of charging cycles and all, or you could use the electricity to power electrolysis and gain hydrogen, which can then either be used by fuel cells, or burned, in a turbine or combustion engine.
A big advantage of the fuel cell would be that it works both ways: your combat vehicles could have backup solar cells, probably stowed away during combat, for emergency autonomous charging / resupplying with hydrogen. Also, electric motors are a lot more robust than combustion engines.
The overall setup would benefit from a range of factors: it could work fully autonomous as long as tehre is any source of water (since you will never have a fully lossless conversion), plus it could benefit from local power grids, or any source of electricity that can be obtained en route.
There is a major disadvantage, though: Fuel cells don't live forever, the catalysts (despite their name) get depleted, too.
And the resulting hydogen tends to be a bit on the combustible side, which does not go too well with the combination of being kept under pressure and being shot at at the same time...
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Military vehicles need to be able to move and fight on demand. Solar energy is simply too diffuse or intermittent for any sort of combat vehicle, except in niche roles (a high flying UAV powered by solar cells across the body and using low power passive sensors, for example).
In fact, what would be ideal for military vehicles would be some sort of light weight nuclear reactor, which would provide huge power to weight ratios and the ability to operate 24/7 and energize multiple systems at once (motive power, active and passive sensors, energy weapons systems like rail guns and lasers, environmental control systems etc.) Of course the need for shielding makes this impractical for ground based vehicles (even nuclear fusion reactors would emit radiation in the form of neutrons, or x-rays emitted due to bremsstrahlung radiation). With a high enough power to weight ratio, even the fabled "flying tank" would be possible.
The way around all this would be to "beam" power to vehicles. When in convoy or doing other administrative moves, they could be supplied by a cooperative station in orbit or other beaming station, and switch to on board power when in contact with the enemy. This would minimize fuel usage when out of contact, and make logistical operations much easier by reducing the amount of fuel needed to be brought forward.
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The energy could be stored and concentrated. The vehicle needs to take on fuel, and how does the fuel get to that spot in the first place? If there was an oasis of sorts it would save the trouble of getting fuel to the stopover points, which is a significant logistics problem.
A depot could have a algae bed producing hydrogen or methane, in a compact self-running unit. The hitch is that it needs lots of area to gather sunlight, and lots of time to stockpile it.
It would also become something that needs defending.
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The surface of a tank is not large enough to provide the power needed to be efficient in combat, even if you have the best power convertor ever made.
You can to externalize the solar panel and transfer the energy to the vehicles with micro wave or a LASER for example.
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Ignoring how we got into this mess, I propose an idea:
The main disadvantages of sticking a solar panel on a tank of ifv are rather clear.
But let me ask you this: Take a look at all the civvilian vehicles(all of which of have strengths and minimums that are more easily taken care of by our tech) do THEY have solar panels all over them? For most of the time, no.
They have those panels at a stationary base somewhere else, and when needed, the civilian ev can go over to it, and recharge.
Why can't ours do the same? Even the chemical burning versions refual at bases and other controlled locations, why can't we?
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Partly due to WB's great [response](https://worldbuilding.stackexchange.com/search?q=user%3A2072%20%5Bsteampunk%5D%20is%3Aq) to my [steampunk](/questions/tagged/steampunk "show questions tagged 'steampunk'") questions, I think the world I'll work on next will have to be [steampunk](http://en.wikipedia.org/wiki/Steampunk) :)
If I had a steampunk cyborg running around, what could he do with his arm? I'll take care of maintenance myself; don't worry about that. I'm more interested in the possibilities of how much he could lift etc, *if this arm was running just on steam-power*.
Obviously, since this doesn't have to really work (and I doubt it really would), I can certainly stretch things a bit (and probably will), but I'd like to have a ballpark figure for lift power in this arm -- most specifically, if it'd be more or less than human strength; with regards to my story, the question is whether an undercover cyborg can be detected easily from the strength of his arm alone.
**How strong would a steam-powered prosthetic arm be?**
To make things easier, assume that a knapsack is available to be used for extra steam-power hardware; like water tanks and such, in case it can't be done with everything inside the arm. I'd much prefer not to need to knapsack, but it's not completely out of the question.
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The actual question is difficult to answer as building steam powered prosthetics is well beyond current science, and even more so beyond the science of the era that actually used such technology. Oddly enough what you apparently wanted to know, whether there is a noticeable difference, is answerable anyway.
It is not really practical to use steam power directly, so the cyborg would use some mechanism to transmit the power. Pretty much the only one applicable to steampunk and at all plausible for prosthetics would be hydraulics.
And hydraulics would actually have a noticeable difference from human muscle. Once the hydraulics lock into position, moving them noticeably with external force almost requires something to break. So the grip of an hydraulic arm would be almost impossible to break. Some padding, gloves and shock absorbers in the system would probably hide this "hardness" in normal use, but any kind of wrestling or other event where human applied strength to the arm would make this noticeable.
As for strength, hydraulics are limited by the pressure used and the area of the pistons. So it really depends what kinds of pressures these systems could withstand and how much space people building would be willing to spend on it. Personally, I would build a system with variable pressure so that the cyborg could balance energy use and risk of mechanical failure to the strength he expects to need. This would imply normally being even weaker than most humans, but on demand having super-human strength available. Even at low pressures the hydraulics would be pretty hard to beat at wrestling though.
Speed of the hydraulics would be dependent on the ratio between the areas of the hydraulic pistons and the valves controlling them. Having reasonable control over speed of movement would require using analog valves with analog logic to control them. This is actually a reasonable steampunk assumption anyway. Maximum speed would be limited by the area of the hydraulic lines. There would certainly be design compromises made to reduce bulk from the relatively long lines.
The power source would be a compact steam engine creating a pressure differential between hydraulic accumulators. Steam engine would have a limited power output and when the cyborg used power at a higher rate the pressure in the accumulators and the system would drop reducing the force the cyborg can apply. By staying still a moment the cyborg could let the pressure increase and have more force available. I think that this would lead to cyborgs thinking before they act. Wait patiently for opportunity and then take fast and decisive action. The redo from beginning.
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Well the first thing would be that the person would stand out because steam power needs a 'large' engine and water to turn into vapor. A steam locomotive spews out huge amounts of steam as it goes down the track. An arm would of course need a fraction of power but having a pressurized container holding water over it's boiling point (and keeping it there) to use as a power source is going to be obvious and dangerous. When the arm moves it is going to need to release pressure and give off little puffs of steam somewhere.
I think steampunk would also accept a battery to power a hydraulic arm.
As Ville was pointing out, hydraulics, even ones small enough to work in a arm can be significantly stronger than an human arm. However lifting ability is limited to how strong the rest of the human is and how well the arm is attached. but being able to crush stones, hands and other things would be incredible.
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Very strong. A steam engine of the same dimensions and materials as a internal combustion engine has much, much greater torque. This is due to the fact that pressure is exerted over the whole of the piston stroke. If anyone has ever seen one of [these](https://commons.wikimedia.org/wiki/File:Miniature_steam_railway_at_Brambridge_Garden_Centre_-_geograph.org.uk_-_63959.jpg) small ride on steam trains pull out of the station they will appreciate this. As pointed out above the arm can only be as strong as the body supporting it, although a hand could be more useful, an unbreakable grip might come in hand clutching a rope, for example.
Most probably there would have to be a backpack, as even very small 'flash steam' boilers are quite bulky for their power output, and they operate at very high temperatures, so not the best thing to carry around stepped to your back. If, however, a catalyst is used to produce steam from hydrogen peroxide (H\_2O\_2) then the apparatus could be contained within the arm, the tanks and reactor built into the bones, perhaps. As the reaction also releases oxygen brass, copper, and bronze would be used, so it fits the aesthetic. Superheated water also releases quite a lot of energy, releasing many times its own volume of steam, so that is another option that could fit into the arm. The last two options would also be cooler in operation, increasing the ability for the cyborg to go unnoticed.
While pistons and cables wrapped around gears at the joints seems the most logical 'muscle' it would be possible to make some variation of 'pneumatic muscle', a tube that shortens in length as it is inflated by the steam, would be more realistic as far as appearance goes. It would, however, have give that a direct piston or hydraulic design might lack, although they can have springs added to compensate.
So what can he do? Given adequate support where the arm is attached he could support his own weight indefinitely, especially if a locking mechanism is included. Crush people's hands and bones fairly easily I would think, although bone is remarkably strong. Probably do the same to light metal pipes. Also, as the hand is metal, and presumably cannot feel pain, can punch much much harder than a normal human.
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For a prosthesis of this type I have always thought pneumatic bladders made the most sense, reinforced one the outside witha webbing such bladders could contain quite large pressures, but would also allow for flexibility more similar to an animal than the hydraulic example above.
In the most lightweight cases, assuming you made a system using rubber hoses reinforced with silk and braided wire, it might not even need an extensive harness to be mounted, while allowing for strength comparable to a human or slightly greater (especially in cases of grip and stability) and could double as a platform for mechanical interface to other devices, vehicles or weapons.
Depending on your power source, actuation method and mounting system this would even be possible to build today.
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There is a guy who is building a pneumatic powered exoskeleton. As a steam engine creates something similar to the high pressured air used in pneumatics I'd see the raw power you could generate similar, too.
As described [here](http://www.ibtimes.co.uk/watch-this-real-life-iron-man-lift-car-using-his-home-made-exoskeleton-1540405) this guy could use the leg part of his exo to lift the rear of a car and the upper part to lift 200kg.
His design is bulkier than a cyberarm but he did it by himself and he could not hide the stuff in his arms because he still has both of them. Whoever builds/equips this cyborg should have more manpower at his service.
So he should be stronger than the average guy. How obvious it would be is, more or less, up to you.
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As strong as you like, but you'll have to take the weight penalty for it. Steam power is hot and heavy (and explosive), there are a few questions you need to answer before you can know how strong the arm will be
How are you going to heat the water to generate the steam?
What pressure are you going to make the steam?
How bulky do you want to make the arm?
Once you have answered those questions then you can work out how strong it is. In terms of control you have a choice, you can either build an arm that can pick up eggs and pluck flowers, or you can build an arm that will rip doors off their hinges but it's going to really hard to have it both ways.
Either way, if you're going to make this realistic by current technology, you might as well give the man a mini JCB. It'll be smaller and lighter.
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I know it is possible to use missiles to shoot down satellites in orbit but what about using rail guns or mass drivers as some sort of anti orbit weapon. I know the idea of a "space gun" shooting people and satellites into space is something that has been consider by NASA and others before but hasn't work for a variety of reasons and has never been done as a result. However those reasons seem to be more related to the cargo's safety which don't really apply to my purpose of using them as a weapon to attack space ships in orbit. Of course there might be other factors I'm not considering like for example maybe the ammo would burn up before hitting orbit. So I'm basically asking wither it would be physically possible to build a giant rail gun or mass cannon capable of shooting an projectile into space without breaking the laws of physics. I'm not asking in terms of technology since the technology of my world is pretty high just wither I'm gonna be breaking the law of physics by including this into my setting or not?
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**Sure**
I mean - we already have anti-satellite technology, we have the ability to intercept orbiting vessels.
However - for a real-world example:
**The Thunder Well**
This is one of those batty 1960s 'Let's use Nuclear everything' ideas - IIRC - you have a Nuclear device, that's in a body of water, in a well, with a Cap on it.
The Nuke goes bang, super-heats the Cap, which is then flung into the atmosphere at **obscene** velocities.
[This was based on what happened here](https://en.wikipedia.org/wiki/Operation_Plumbbob)
The infamous manhole cover that was shot into space at an estimated velocity of 66 Kilometers **per second**.
The theory being that these Thunder Wells would be precisely triggered (something something orbital mechanics) in order to intercept something in outer space.
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See also [Project HARP](https://en.wikipedia.org/wiki/Project_HARP). This used long-barrelled guns of up to 16 inches diameter to shoot a projectile into near space. The highest it got was 180 Kms with an 84 Kg projectile. Whatever it shot had to survive an acceleration of 15,000 g. At the time this was seen as an economic alternative to rockets. As history turned out, rockets and rocket guidance developed rapidly. If you were trying to hit an ICBM, rockets were a much better proposition because they could be steered.
Not a success, but HARP did show that you could launch a projectile from Earth's surface to inner space.
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"Yes, but."
Richard Kirk's answer basically tells you what you need to know... [humans were able to shoot a projectile above the Kármán line back in the 60s](https://en.wikipedia.org/wiki/Project_HARP), and technology has marched on a bit since then. The Martlet projectiles were able to carry rockets and useful bits of equipment, so there's scope for steering at things, or just blowing up and forming a nice big debris cloud for things to crash into (and as the debris is going at suborbital velocities, it'll clear itself).
Problem is though, a gun-fired projectile has to get up to useful speeds before it leaves the barrel, and even for very long-barelled guns (and the HARP guns had barrel lengths between 36 and 54 metres!) this requires significant accelerations and hence needs electronics and rockets that can survive that sort of punishment. Clearly humans *can* make stuff that can survive thousands or tens of thousands of gees of acceleration, but they can also make stuff that has a much more relaxed performance envelope that's either more capable or cheaper or both. Even the [Sprint](https://en.wikipedia.org/wiki/Sprint_(missile)) missiles "only" hit 100 gees. HARP projectiles had a muzzle velocity of over 2.1 km/s, but that was the fastest they would go. The Sprints topped out at 3.4 km/s, but the [ASM-135](https://en.wikipedia.org/wiki/ASM-135_ASAT) could manage 3.9 km/s with lower accelerations and the [SM-3](https://en.wikipedia.org/wiki/RIM-161_Standard_Missile_3#Anti-satellite) hits 4.5 km/s and all those missiles hit those speeds higher up than an artillery shell and so waste less energy battering through the thickest layers of the atmosphere. Speed is range, and unless you can hit a good 250 km upwards your gun isn't going to be much use for hitting things in orbit.
A more powerful gun can shoot higher, but it will probably exert even higher acceleration forces on its projectile and will suffer even more from atmospheric effects. A railgun or coilgun also involves very high electrical or magnetic fields, to add to the payload's woes. You could shoot a dumb projectile, but shooting straight over hundred of kilometres whilst subject to significant aerodynamic loads to hit a (probably) small object travelling at may kilometers per second? Seems dubious. Also, suborbital projectiles gonna come back and risk falling on something. If you managed to shoot something out of the atmosphere on an escape trajectory into interplanetary space that's less hazardous, but still space junk (and requires an extraordinarily powerful weapon).
A single antisatellite missile has a lower performance requirement for the hardware it carries and for its launcher and has a much better ability to steer itself and drop some suitable [kill vehicle](https://en.wikipedia.org/wiki/Exoatmospheric_Kill_Vehicle) at a place where its prey will find itself in due course. You could potentially order it to abort (eg. self-destruct) if you changed your mind, or it missed, or there was a problem, which reduces the chances of collateral damage.
You *could* use a railgun to do the same job, but honestly you probably shouldn't.
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The problem is the atmosphere. Its what creates friction and resistance and is as much a hold back as gravity. So lets imagine for a moment a rail gun, slightly slopped that leaves the harshest part behind, with the barrel evaccuated and lifted.
Another hypothetical solution might be to create a "add-hoc" vacuum tunnel. Meaning.. you shoot a laser ahead of the barrel, ionizing the air into a plasma-channel, charge the channel and basically turn it into one long lightning. And where there is lightning, there is thunder -aka air rushing in to fill the vacuum left by the plasma.
And in that vacuum, your bullet traverses into the outer atmosphere.
<https://llr-fet.eu/>
<https://en.wikipedia.org/wiki/Lightning>
All the other problems apply to the project though. High G-Load on the projectile.
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Its an excellent question and I don’t know why people are falling on it as a pack of wolves. In fact the edit isn’t necessary either.
Some people have mentioned the high velocities. Well we have Project Thor, which proposed sending thin but long aerodynamic tungsten rods in excess of mach 25 through the atmosphere. They would lose a lot of speed in the process, but I don’t see much reason yet that you can’t just increase the velocity even further. After all, you are on the ground in a pretty high sci-fi setting. Your power production would make orbital bombardment look like fireworks. Or as Isaac Arthur put it, if they throw rocks down at you, you throw mountains back up.
You might have to replace the rails for each shot, but for a high sci-fi setting it wouldn’t be that difficult to have disposable rails that are simply dumped into an industrial cycle to be remade in a couple of days while you store enough rails alongside your ammo to fire thousands if not hundred’s of thousands of shots. And that is assuming you don’t have some fancy maglev hovering launch vehicle which doesn’t degrade the rails.
If your gun is mostly vacuum, opening the front for fractions of a second to launch the projectile, the acceleration would become exceedingly easy. You’d likely have several stages of airlocks at the end of your gun so it doesn’t instantly slam into the full air, each opening and closing in a moment to let the projectile pass and then changing the air content again to what you want. This is actually something proposed for a maglev train in a vacuum tunnel for quick transport, which a high sci-fi would have access to and mean the technology base exists both in military and civilian sectors.
So yes, you could use it.
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How many voyages a year would a single trading ship make, usually?
Firstly, please let me know if I'm using the wrong terms for any part of this question. I suspect my answer is already out there somewhere, but I imagine I'm not asking the right question.
So, this is a fantasy small island (around 8000 square miles) with two main ports. It's the largest island of a set of islands, with a large hook landmass to the South and a cold, but sustainable larger landmass to the North. I reckon it will take around a month and a half to two months to do a trade run with some of the closer, larger land masses (with about a week in between to get the stuff off and on the boat).
I have a few options to make sure my dude is back and fore his home base (for example, using it as a stopover between the north and south, or trading along the other chain islands in closer proximity), but I'm not really sure how many times a year he'd make a journey on the same ship.
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Unless it's a scheduled bus run with cargo & provisions sorted at both ends then it's always open ended how long is spent in port. Regular scheduled runs usually are a day or less in port as everything is ready for them when they arrive.
Otherwise cargo needs to be sold, and cargo and food etc,. needs to be acquired for the return. Both of these can take a lot of time and effort. Time is rarely a problem until under way with perishable goods. Ships can and do travel one leg just with ballast, but that doesn't fit your scenario since you seem to want two way trade.
If you show up in port and need to sell your cargo in one day, then expect to get fleeced. If you need to buy your cargo in one day you can expect to get fleeced even worse. If sufficient supplies are not stockpiled already or are problematic you need to wait. So you don't constrain the port time on lengthy voyages. Your 2 month voyage and a week stopover each end seems fine to me.
Ships make all their money tied to dock. Nothing while sailing. The solution to more time making money is to decrease sailing time, not dock time. Dock time is also for the benefit of your sailors. These are skilled workers, you need to keep them happy unless you're using slaves. A week or more is a reasonable period to have them out in shifts making merry with their pay. 2 or three weeks would be better if you have a big crew.
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Ships make no money tied to a dock. They sail as quickly as they can between their ports of call, spend the minimum possible time in port, usually just enough to unload goods, and load goods for the next voyage, plus supplies, do any necessary maintenance and set off as soon as possible.
A sailor on such a ship would likely spend most of his time on the ship, since he would only be paid for the time he has spent working. If he took leave, it might be until the next time the ship was in port.
As to how many voyages per year, just calculate how many the ship *could* make, and that's how many its owners will try to *get* it to make.
The answer above is assuming that the owners of the ship will have pre-arranged cargoes and shipping routes, and the captain and crew need only travel between the pre-determined ports and load and unload as necessary.
However, if a ship was a tramp freighter, matters would be different. Tramp freighters operate on commission, going wherever they are needed with whatever cargoes their crew (often the [purser](https://en.wikipedia.org/wiki/Purser)) can find. For such a ship, more time may be spent in port while the purser advertises for cargoes and follows up advertisements for cargoes requiring a ship, or a cargo purchased for transport to a destination at which it might be sold.
During this time, the ship would be resupplied, maintained, and some crew might take leave.
However, once a cargo had been found and a destination determined, the ship would be loaded as quickly as possible, and would proceed to its destination as quickly as was safely possible.
Again, the less time that is spent in securing a cargo and the less time is spent travelling to its destination, the more money the ship may make.
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>
> How many voyages a year would a single trading ship make, usually?
>
>
>
Regarding your exact question:
Whether the destination port knows when to expect the ship to arrive can affect which of the two great answers below are the better answer for your story.
I think you should decide if there is a means of communication between the ports other than the ships themselves. (Carrier pigeon maybe?)
The two great answers above are **independent trader** (also called wildcat in modern vernacular) and **delivery service** (also called a *scheduled bus run* above). One would be the best for your world, but I don't have enough information about what you want your story to be/achieve.
Related to your question:
I'd recommend further thought about how important shipping is to the story.
If the purpose of the question is to only answer the question 'how many round trips' then measure the distance between the points and use 5-6 mph (8-10 kmh) to get the travel time. Subtract one round trip per year (if you want) because bad wind has more impact than good wind. Draw out a map of your islands and put arrows between them that indicate the travel time and you're done.
This is sometimes called "hand-waving" and there's nothing wrong with it if your story doesn't focus on the specifics of sailing. Your question's main character is a sailor, but how much does your story focus on sailing?
If this is a love story between the sailor and someone, then maybe you should do lots of hand waiving.
If part purpose/plot of the story is to immerse your reader in the sailing aspect of the story, they you'd want to think about which of the below you would want to address about the 'real word' aspects of sailing:
1. Is there bad weather?
For example, is there a hurricane season where ships must be in port.
Or if no ports are safe in a hurricane, what does that look like?
My brother had a Spring Break job in college where he and some friends were flown to the Northeastern United States in early March, then they would sail a nice sailboat to the Carribean for its rich owner. The owner would fly down and use it during the Summer, and then someone else would sail it back up to the NE in August (before hurricanes were expected) where it would remain for the winter. This is intended as a real-world example to help your thought process about hurricane type bad weather, and what people do today to avoid/account for it.
2. Do you want to bring in boat maintenance? (Mentioned by @quarague & @Montey Wild)
All boats need maintenance.
Even a modern fiberglass hull boat, that isn't in an accident, needs regular maintenance/replacement for its fittings - and your story has wooden boats which in addition to fittings and sail maintenance, need regular tar and pitch maintenance on the hull to avoid leaking. All ocean boats also need treatment for barnacles that attach to the hull and slow the boat down by creating drag. (barnacles grow into the hull, decreasing its structural integrity over time)
3. What about human aspects of the sailors, such as length of shore leave? (Mentioned by @kilisi)
You mentioned your dude being on the "same ship" - so maybe all your boats have a quick turnaround time, but most sailors want more time in port and are willing to sail on the next ship?
4. Ballast (Mentioned by @kilisi)
Expanding: You cannot sail a cargo ship without a certain amount of weight in them (cargo + ballast) because they are *designed to carry* a lot of weight.
They are too unstable without it - they ride to high in the water and would likely capsize (tip over) without carrying the minimum weight they are designed to carry.
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**Depends on the winds.**
Most sailing ships with multiple masts [work best](https://en.wikipedia.org/wiki/Point_of_sail) if the wind comes from the side and behind, not directly behind. A single sail may work best with the wind from directly behind. In either case, wind coming from directly ahead is *bad.*
So if you want a round trip, either you need a change of wind directions between the two parts of the trip, or you cannot sail the most direct course.
* The more modern the sail rig is, the better the ship will be at [tacking](https://en.wikipedia.org/wiki/Tacking_(sailing)), that is moving both upwind *and* sideways. This will give much slower effective speeds than regular sailing.
* Find some sort of circle route, where each leg has dependable winds. Google [trade winds](https://en.wikipedia.org/wiki/Trade_winds). Your world might have a pattern fundamentally similar to Earth, or perhaps you have a different number of [Hadley cells](https://en.wikipedia.org/wiki/Hadley_cell). (Fantasy sailors would not understand the cause, they just note the effects.)
* Large ocean currents like the Gulfstream might help or hinder progress.
* Finally, traders might have to wait for seasonal changes.
So in the worst case, you get one roundtrip per year. Sail one way in the most favorable season for that direction, sail the other way in the most favorable season for the other direction.
In a somewhat better case, one direction usually goes smoothly, but the other direction means tacking and even waits while adverse winds lock the ship in a bay or harbor. Say three weeks one way, three months the other way, total four months per roundtrip.
In the best case, you get something like the east-west Atlantic crossing. Quick crossing both ways, but the landfall is not where you want but rather where the winds take you, and then the ship has to sail north or east to get to the new starting point. (This is also a good match for navigators who can do latitude but not longitude, see [chronometer](https://en.wikipedia.org/wiki/Longitude#The_chronometer)).
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## Setting
In the not-too-far future, Mars hosts a few mining complexes that extract, refine and send materials back to our planetary system, as well as some scientific research bases. Commutes between them and Earth are sparse and mainly reserved for the ore, with even sparser travels dedicated to rotating people in and out, so those complexes are of course equipped to be able to survive in autarchy for extended periods of time if need be — facilities, gear and qualified personnel.
## When suddenly
Oh no, something funny happens to people on Earth. Due to the nature and unfolding of the event, travels between Earth and Mars have not been resumed in time for the colonists to be brought back before such an operation became impossible, so now they're stuck on their barren rock indefinitely, with no contact with anyone.
Well, fuck it. They've got mines, mining gear, refineries, automated and remote-controlled instruments and vehicles capable of assembling stuff and repairing each other, advanced machinery supported by A.I. software designed to synthesize materials ranging from anti-radiation shielding to medical products, all the brains (organic or artificial) needed to operate and engineer; they'll just build their own ship and get back to their homeworld on it.
## The catch
For story reasons, I need this enterprise to be a multi-generational one stretching as long as a few centuries. Tee-hee.
## So
There isn't really a shortage of factors I can leverage to push back the project's finish line:
* **The sheer size of it.** Even with a relative abundance of raw resources and tools that are advanced for their original mission, the sustained engineering and building efforts alone make for a formidable challenge, I don't think I really need to expand on that. Especially since the assembly will be made in orbit, to stay in line with the "realistic-looking" approach I would like to take.
* **The resources allocation balance between the project and basic survival.** Dedicating them to the ship means dedicating less to other daily essential tasks. This includes material resources as well as the personnel themselves. And survival will always take priority over the ship, should resources become scarce for whatever reason.
* **Building the ship might involve, at some point, stripping and repurposing parts** from the colony among the ones most difficult (if possible at all) to manufacture — I'm mainly thinking about microchips for instance, but it could also be extreme late-game cases like using the generator(s) to power the ship. If it comes to that, then they start trading the operational status and the productivity of the colony for progress on the project.
* **So much could go wrong with the population.** I should probably do the math to determine how many people there are, but regardless of what the figures are, the nature of the project (and the conditions under which it's being undertaken) forces the colonists to not grow over time, or to a minimal extent. That means everyone is an actively valuable individual, and any untimely death by accident, disease, homicide or suicide is a potential blow to the project. Also if, God forbid, they fall below the minimum viable population number, there isn't even the hope for an eventual recovery.
* **The previous point can be extended to gear/buildings.** Having repair machines that can also take care of each other is one thing, but losing a complex, specialized facility to something as stupid as a fire is another.
* **How do you find time for the ship when you've got kids to care for, raise, and teach to?** As I was writing the point about the population, I realized the colonists will also have to do that eventually — and do it well. They really can't afford to neglect that part, as ending up with a next generation that is not up to the task of carrying on their work makes the whole thing utterly pointless. So this is a major strain on both resources *and* the time they've got on their hands.
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Those are the main things that come to my mind, I'm sure there are others. So my question is: several hundreds of years to complete the ship, in the realm of reasonable suspension of disbelief or way overkill?
**Additional note:** for the sake of framing, I should specify that whatever happened on Earth affected the population, not the environment, which the colonists know. Earth is still perfectly inhabitable and infinitely more preferable than Mars as a home, so they do have a strong incentive to go back there, as opposed to just declaring that Humans are now a Martian species and roll with it.
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**They don't know how...**
Granted, it wasn't much of a test, but on a whim I tried to find the construction schematics and fabrication details for the Space Shuttle (any one of them) on the Internet.
I failed.
We tend to think that the all-knowing, all-powerful Internet has everything on it. In reality, it has only a smattering of human knowledge. It may be true that things are *accessible* if you know how and have the right credentials... but the fact of the matter is, I can't find the information I need to build a space shuttle.
Neither can your Mars inhabitants. In fact, they can't find anything other than cutaway drawings of anything that would be remotely useful. They can't even find specs to build old stuff. Which isn't unreasonable. Why haul the entirety of human knowledge to Mars when chunks of it can be made available upon request? That minimizes the infrastructure required to house, maintain, and make all that data available.
*If you think about it, it's really unlikely that there's one spot on Earth that's publicly accessible and hosts all of the knowledge available via the Internet. It wasn't actually designed that way. I'd be surprised if even Google had all the eggs in one basket... even accounting for redundancy. Distributed resources are always more useful than a single resource.*
So, the reality is that there will be a LOT of experimentation, innovation, and investigation *just to get the knowledge needed to push a ship from the surface of Mars to anywhere else.* And when you start thinking it through, the amount of information that's needed to do that even today... *is breathtaking.* And we've already worked it all out.
They haven't.
So I can easily see multiple generations just on this alone.
**Disclaimer**
By definition you need to work *weaknesses* into your system that rationalize the goal you're seeking. That's really not hard. Your AI is focused on *specific solutions* to *expected problems.* Why worry about programming an AI-controlled medical center to do full research and analysis on *any previously unencountered pathogen* when the odds of that happening in a controlled environment like Mars makes the whole idea cost prohibitive? Just ship it back to Earth where the military can classify it quick anyway. And why build an AI to control your mining operations that also knows how to figure out rocket engines?
Your people will be reconfiguring what they have something awful to do the one thing humanity is reasonably good at that usually takes a whomping long time anyway: inventing something out of nothing.
And in the mean time they're *also* trying to figure out how to make due without the regular Earth supply runs. No city on Earth today is wholly independent. Neither's Mars. *Now you have a multi-generational race against time.* I like it!
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There's some options here:
**1: There's no Rocket construction, Test and Launch facilities on the surface of Mars**
So, you said that people regularly rotated in and out before something happened, but if we presume that there is a ferry type spacecraft that takes the bulk of Cargo/Personnel from Mars to Earth and that it stays in orbit (getting into Orbit takes a lot of fuel and energy) and it uses smaller vessels to ferry from Orbit to the Surface, you could make a reasonable case that it never made sense to have a Rocket Facility on the surface of Mars.
Finding a suitable location (Flat, Away from the populace - safe from meteor strikes etc.) could easily take a few years.
Then you've got to terraform the launch site - in earth on a regular construction project, this could take several months to over a year - but we will double/triple the time taken cause Mars and no atmosphere and the additional challenges of working not on earth.
Finally once the site is prepped you need to actually build the facilities - think of how long it must have taken to build Cape Canaveral from scratch - and again, double/triple the time taken cause atmosphere. So just to build the area to start this project, we've got a 20-30 year project.
**Rocket motor Testing!**
So - anyone right now could jump online and learn exactly how a rudimentary, open-bolt, fixed firing pin Sub-Machine gun works. Big Spring, Big chunky bolt, Barrel, trigger/sear and Magazine. Easy. Right? Well, although the mechanics are relatively simple, there are a lot of Gotchas that without doing a lot of trial and error and starting from a position of Zero gunsmithing experience takes **time** - And that is an object with 3 moving parts (Bolt, Trigger and the Magazine) - Something like a Rocket Motor - which although in it's most basic form is 'simpler', when we are talking about a motor that is capable of inter-planetary travel - is much more complex - we will need years of testing. And we can only safely do that testing after we've built the facilities. Call it 20-30 years. Consider this - there are nations on earth right now that know what an ICBM is - have seen American and Russian Missiles and know the basic theory of how they work (Even Werhner von Braun would understand how a modern rocket works...) - yet are spending years upon years to produce something that reliably works and does that they want it to. So already, we've got 60 or so years worth of time spent.
**More Testing**
So, we've got our Rocket, we've got our facilities - let's jump in and go, right?
Would you be willing to do this? Hell it took the Apollo missions 10 years almost to get from first tests to landing on the moon. But Mars is much further, despite achieving this in the 60s, we haven't put a man on Mars yet - so that's another 60 years of faffing around testing, overcoming technical challenges etc.
So we are up to around 110 years.
**Catastrophic Failure and set-back**
Nothing sets a project back like a high-profile catastrophic failure. Think Apollo 1, Apollo 13, the Columbia Disaster etc. etc.
You can easily waste a decade or two on a major safety event that was high-profile *and calls into question the competence and leadership of the team* - something where even a lay-person would be like 'How did they miss that?' - The O-Ring on Columbia is a perfect example of this.
And this leads nicely to the best way to make a project go into development hell that lasts for a long time:
**Politicking and Corporate in-fighting**
The challenges and the physical construction and time spent can give you ~ 100-150 years of believable reasons for the delay. Building everything from scratch, having to develop the practical skills of rocketry, the inherent challenges of large-scale projects in a hostile environment. But nothing will slow a project down more than a bunch of self-righteous Middle Managers, Bean Counters and Political whores (e.g. people who play office politics and have their own little agendas and suck up to the boss - not ladies of the night)
Throw some of that in at key junction points and you could probably stretch it out to over 200 or so years.
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I'd politics and microchips.
1 - As soon as the shit hits the fan on Earth (caused by politics, right?), you'd also have factions on your colony. Not necessarily the same as on Earth, but those for assigning all resources to get back as soon as possible, those who don't want to go back, and those more prudent in between. Build some infighting, sabotage and colony splits and it can last a LONG time before they manage to build anything difficult.
2 - Microchips are one of the most difficult thing to build right now. There's only 2 (3?) factories on earth for the most advanced ones and they cost tens of billions and decades to build. There's no way they can replicate them, unless they want to use Apollo-era guidance systems for their return trajectory. So the longer they stay, the fewer microchips they'll have and the more 'native' they'll become (cf 'politics' above).
Compared to the above, building a rocket engine to leave Mars' gravity well sounds almost trivial if you have some quality metals.
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**Century or less**
Your colony is self-sufficient, they have facilities to produce stuff they need. It needs to be, as you cannot have a large scale colony off-world because lifting stuff ot of Earth's orbit is way too expensive for the colony to be dependant on trade with Earth. And if for some reason your colony need some thing from Earth to survive, then your colonist will die out shortly (and thus no story will happen).
As for the problems other answers provided: they seem to forget that we put a man on the Moon just years after launching the first satelite. And we lacked much of the knowledge we have today. Often the hardest thing is to figure out that something is actually possible, and your colonist will KNOW it is possible to build interplanetary spaceships. So even if they had to go trough space program from scratch it wouldn't take THAT long. As for microchips... Even a few decades ago almost every important country build its own microchips. Sure, your colonist wouldn't have knowhow to build cutting-edge ones right from the start, but they can develop that tech, same as with everything else. Just look what we achieved in the last century on Earth!
Honestly, the biggest issue in that spaceship building project is the population size. You need a certain number of people to even attempt such big projects. But the number of people on your colony cannot be super small, as otherwise they would have inbreeding issue and you would again have a problem of them never finishing the spaceship (and probably dying out).
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Never mind how the tungsten sphere formed. That's part of my pet projects, and I will deal with the question of how a nearly pure sphere of tungsten the diameter of the moon formed in space later.
So, if you read my question right, there is basically a tungsten moon orbiting my world at a distance of about 384,000km away. According to my calculations, a moon-sized sphere made of tungsten will be around 5.778 times as massive as our moon. So there might be powerful tides on this planet, but let's not consider that now. The host planet in question has the same size and mass as our Earth.
The host planet is basically a rogue planet that formed in a nebula, without a star. So I was looking for a heat source, and a tungsten moon seemed ideal.
So here's the real question. I want my tungsten moon to act like a "Sun", which means that it will radiate enough heat and light to keep my planet habitable. Meaning that the planet can host liquid water.
The tungsten moon is hot, like extremely hot. The surface temperature of the tungsten moon is about 3390°C. The crust of this moon is solid, but dangerously close to the verge of melting. This means that the tungsten moon is acting like a giant induction heater in the sky of my host planet, providing heat and light to my world.
However, I am at my wits' end trying to figure out a heat source hot enough to heat up the surface of my tungsten moon to the desired temperatures.
**What is an ideal heat source to keep my tungsten moon hot enough to radiate enough heat and light for life to exist on my world?**
# Criteria:
* Needs to last for 3-5 billion years, not much.
* Sufficiently energetic enough to heat up the surface of my tungsten moon to 3390°C.
* Anything is allowed as long as it doesn't have any major side effects. For e.g. a core of uranium and other radioisotopes decaying and producing tremendous amounts of heat is okay, as long as it doesn't produce too much radiation that can damage life-forms on my host planet.
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## Barring any nuclear options or active heat sources, the answer is a hard NO.
I'll use a simple model for radiative cooling, [brought to you by Hyperphysics](http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/cootime.html), to gauge the timescale for the Moon-sized rock to cool below useful temperatures. ([Here's a link to a Desmos calculator I made while preparing this answer.](https://www.desmos.com/calculator/yysbivkdcz)) The model is built from the [theorem of equipartition of energy](http://hyperphysics.phy-astr.gsu.edu/hbase/Kinetic/eqpar.html#c1), which relates the temperature of a system to the average kinetic energy of its constituents.
$$KE=N\frac{3}{2}k\_{B}T.$$
It is derived by dividing the equation of energy by its derivative w.r.t time and then integrating over temperature, solving for cooling time (simplified for a sphere):
$$t\_{cooling}=\frac{Nk\_{B}}{8\sigma \pi r^2}\left(\frac{1}{T\_{final}^{3}}-\frac{1}{T\_{initial}^{3}}\right).$$
* $T\_{initial}$ and $T\_{final}$ are the starting & ending temperatures of the sphere in Kelvin;
* $r$ is the radius of the sphere in meters; in this case, the lunar radius $\text{1,740,000 m}$
* $k\_B$ is the [Boltzmann constant](https://en.wikipedia.org/wiki/Boltzmann_constant), about $1.38\cdot10^{-23}$ $\text{J⋅K}^{-1}$;
* $\sigma$ is the [Stefan-Boltzmann constant](https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_constant), about $5.67\cdot10^{-8}$ $\text{W⋅m}^{−2}\text{⋅K}^{−4}$;
$N$ is the number of particles in the sphere, and may be calculated by $N=\frac{mN\_{A}}{M}$, where
* $N\_A$ is the [Avogadro constant](https://en.wikipedia.org/wiki/Avogadro_constant), $6.022\cdot10^{23}$$\text{mol}^{-1}$;
* $M$ is the molar mass of the particles, in this case the molar mass of tungsten, $0.184$ $\text{kg mol}^{-1}$;
* and $m$ is the mass of the sphere in kilograms, and can be calculated by multiplying the density of tungsten by the volume of the Moon: $m=4.25\cdot10^{23}$ $\text{kg}$.
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The temperatures we're interested in are around 3,400 °C. Tungsten starts to vaporize at around 5,600 °C, so let's use that as our $T\_{initial}$ and 3,000 °C as our $T\_{final}$:
$$\text{105,000,000 seconds, or 3.3 years}$$
The model is probably accurate to within a few orders of magnitude, and so far it suggests the sphere will cool from its boiling point down to below the desired temperature in a millennium or less. (I don't know where you got the idea that 3-5 *billion* years is "not much".)
Let's say the tungsten moon forms a heavy tungsten atmosphere whose immense pressure raises the boiling point of tungsten, perhaps something like 16,000 °C at something like $10^9$ $\text{Pa}$:
$$\text{126,000,000 seconds, or 4.0 years}$$
Still within a thousand years.
We can't go much higher than this as the energy we've given this sphere already surpasses 1/10th the gravitational binding energy of the tungsten moon:
$$E=N\frac{3}{2}k\_{B}T\_{initial} = 4.70\cdot10^{29}\text{Joules}$$
$$E\_{binding}=\frac{3Gm^{2}}{5r} = 4.15\cdot10^{30}\text{Joules}$$
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There's just no way to get what you're looking for without alternative energy sources. The rate of cooling follows an exponential decay. The Stefan-Boltzmann law states that the radiant power of an object is proportional to the fourth power of temperature. The tungsten moon will lose the vast majority of its internal heat initially, when it is hottest, and will cool more gradually onwards. Not even stellar remnants like neutron stars can do what you're asking.
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Same [reasons the earth's core is hot](https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget): **1)** it got very hot a few billion years ago when it formed, and that heat has still not fully dissipated, **2)** decay of naturally occurring radioactive isotopes (which I think is still under "Should not be something like nuclear fusion or antimatter").
**PRIMORDIAL HEAT**: Earth [has 5-15TW of energy](https://www.nature.com/articles/ngeo.2007.44) still flowing out of the core constantly caused by the intensity of the planetary accretion.
I have less confidence in this paragraph than the rest, others with more knowledge can chip in: I think that something made of tungsten coming together would have more primordial heat, because the overall density of the moon is very high and so the core was compressed more intensely with more heat when it formed.
**RADIOGENIC HEAT**: Earth's core has uranium-238 (238U), uranium-235 (235U), thorium-232 (232Th), and potassium-40 (40K), and these break down and create heat (that Icelanders then use to have hot showers).
You can, as a worldbuilder, put any amount of radioactive materials in the core of your "nearly pure sphere of tungsten", unless it's very important that it be so pure. Earth is 135 parts per million potassium (across all isotopes), 51.2 parts per billion Thorium, and 14.3 parts per billion uranium. (Morgan, J. W., & Anders, E. (1980). Chemical composition of Earth, Venus, and Mercury. Proceedings of the National Academy of Sciences, 77(12), 6973–6977. doi:10.1073/pnas.77.12.6973). So you're not really compromising on purity here hardly at all.
The core could be radioactive, the surface could be tungsten. Don't worry about harmful rays coming off the moon; gamma rays don't penetrate lead, let along kilometres of tungsten.
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I think antimatter is the way to go tbh. There's no obvious way a tungsten moon could appear so you're not losing any scientific plausibility to make it an anti tungsten moon instead. Every asteroid and spec of dust annihilates on contact providing energy that will last as long the mass of the moon does. Easily billions of years if it's big enough to start with.
Otherwise uranium moon, but that would be massively over critical mass and blast itself and your planet into atoms. The bigger the mass the more explosive force so there's no way to overcome that, unlike with antimatter where you can have as much inert mass as you want as long as the regular matter colliding with it doesn't get too much at once.
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OK, so, as a bit of scene setting in a story I am writing, a small group of people has landed on a nearly exact replica of Earth (atmospherics, geology, and physical parameters are nearly the same as Earth) and have set up a town there. Now the question I'm wondering:
**Horses or Rovers? which is better for a small colony town with limited everything?**
that's it
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**Use the local horse equivalent.**
[](https://i.stack.imgur.com/9ZxSs.jpg)
<https://www.deviantart.com/louisetheanimator/art/Green-Alien-Goat-878439701>
For example, the alien Giant Pygmy Goat as depicted here. You can tell it is alien because it is green. Your people were going to use rovers but the planet is loaded with alien goats who were totally up for the project. They are not as big as horses but they are really strong. The short colonists can ride just fine. Tall colonists use spurs but instead of a spike it is a castor wheel so their heels won't drag on the ground. Really tall ones might ride two goats at once. The goats are cool with all that.
Also the GGPG (giant green pygmy goats) are friendly and funny, and they give green milk which makes awesome GGPG cheese.
Your people Go with the Green Goats!
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Horses' needs don't scale down very well, which would make them a liability for a small colony. A larger one could get more use out of them and better mitigate the problems.
Problem one is *getting there*. A spaceship is not a very good environment for a horse; they need space to run and exercise, and they need a lot of food and water which adds to your supply needs. The bigger the colony ship, the easier it is to find large open spaces for your livestock. You also need to consider what g-forces a horse can survive (I can't really imagine one being strapped into an acceleration couch...) and whether that will fit with your launch vehicle. Rovers, in contrast, pack up nicely and will handily take any g-forces your colonists will.
Problem two is that horses require a lot of specialized care and, worse, specialists that don't really overlap with your existing needs. If your rovers are electrically powered, for instance, then the batteries and motors they use run on the same principles as all the other electrical equipment in your colony. Your motor pool mechanics probably have enough know-how to swap in and fix a balky AC unit or repair a generator. On the other hand, if you keep horses, those skills are less transferable to other situations that come up. Maybe your horse handlers can keep other livestock, but that's about it. Again, in a larger population this isn't a big deal. A population of a million can afford to specialize in tons of little fields. A population of a thousand can't; each specialist is a potential pain point if that person is injured or sick.
Problem three is, where are you planning to go? A small colony doesn't really need a lot of transportation. As you describe it, they only have one town, which is presumably fairly compact. You don't need sprawling suburbs or huge factory districts. Most of the settlers' lives probably take place in easy walking distance. If your trips are fewer and further between, a rover you can park in a garage and forget about has a big advantage over a horse that still needs care and feeding whether or not you go anywhere.
As an aside, have you considered muscle power? A boat or a bicycle has far fewer moving parts than a rover, needs less maintenance than either, and is easy on your fuel supply too. And they require very little specialized know-how. They're not suited for every terrain but the nice thing about being the first colonists is, you can pretty much take your pick.
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Depends on the time scale, how many people you have, and what sort of robotics you have.
A factory to build engines and produce steel and rubber and coper wire and such is a pretty big deal. Depending on your battery tech either electrical generation to charge the batteries or fossil fuel production to fuel them is also a big deal.
Horses can make more horses as soon as you let them. All you need is grass and water and simple shelter like a barn and you get more horses.
Horses do have subtantial maintenance involved, and there are some skills. Riding a horse takes some skill. Blacksmithing takes some time to learn. Making a good saddle is a significant skill. Horses must be reliably fed even in the winter. They must have reliable water supplies. They need substantial space. They must be trained and kept in training. And horses can be susceptible to a variety of health issues. So it's not automatic that they are superior.
If your colony had some honking-advanced robotic manufacturing, you might be able to tell the robots to go build a bunch of ATVs and motorcycles and SUVs and spare parts and such. Probably they can make such faster than horses could breed up enough for everybody. In this case, the powered vehicles are probably preferred.
If it's a very small colony and they don't have robotic manufacturing, probably a big factory to make vehicles would be more than they could support. In that case, probably horses would be easier, faster, and renewable.
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If the "horse" is a native animal rather than a terrestrial import then the horse may be the best bet providing it has the temperament of a horse familiar to us it could be useful.
Rovers will not last as long as a population of horses. Within a few years or decades at most in rough terrain, the rovers will be dead needing spare parts (that presumably can't be manufactured in a small town). The horses will be around for millions of years.
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There was a quote in a Pournelle novel, which roughly went "tractors wear out, horses make more horses." So the questions would be:
* How small is a small colony?
* How easy is the resupply?
* How long do you plan to stay?
A rover needs fuel. What do you plan to use? Hydrogen, split from water by electrolysis? Keeping hydrogen in tanks can be tricky. Hydrocarbon biofuels from the fields? You need more vehicles for farming, then. Fossile fuels, if the planet has them? Start drilling ...
Tires wear out. Try to imagine what it takes for a small town to produce modern rover tires. First, you need either rubber or hydrocarbons for synthetic rubber. Different compositions for different parts. High quality if you want the tires to last. Then steel wires. Build them all up and bake them together. How much industry does that take?
Next, pick some nuts or bolts to wear out. You won't make a replacement in a village smithy, it will take a factory. With steel from a steelworks. Do you fire that with coal, coke, or perhaps awesome quantities of hydrogen? We're not talking about a small colony any more.
Rovers are the better choice if you have enough of a population to justify all those factories. This population could be spread over many worlds if communication and transport are easy enough. "Only two more rover gearboxes in storage. Time to order some new ones." If a few hundred, a few thousand people are on their own, a rover lasts until some vital part wears out. A horse lasts until it dies (and horses die terribly easily). But a fleet of rovers will break down, one after the other, while a herd of horses might breed.
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Horses could be brought as frozen embryos and grown in artificial wombs, reducing the storage space needed, so assuming the vegetation here is edible to them, this System could work. It seems a bit unlikely that this alien grass would have all the necessary nutrients as earthly god-fearing grasses, but hey, everything else here is the same as Earth!
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Let's break it down into advantages and disadvantages.
Horse advantages:
* Free food (via grazing, assuming compatible biology and appropriate season)
* Superior all-terrain capabilities (While advanced vehicles are getting closer, legs still beat out wheels in most scenarios)
* Limited self-repair functionality, but rather fragile overall
* Automatic reproduction: provided time you can grow more horses
* Can be used as an emergency food source
* Maintain and operable with pre-industrial technological base
Horse disadvantages:
* Horses require daily care and expert knowledge in multiple fields to handle properly
* Live horses are difficult to transport in a vehicle
* Horse range and cargo capacity is rather limited (just barely over human range)
* Disobedience / unpredictability when facing adversary conditions
Rover advantages:
* As much range as there is fuel/power (thousands of km with chemical fuel, many hundreds with batteries)
* Protection from the elements and wildlife in closed cabin
* Potentially very large cargo carrying capacity
* Direct ability for power-hookup to external equipment
* High speed provided prepared driving surfaces
Rover disadvantages:
* Requires fuel/energy manufacturing (or extensive stockpile)
* Requires industrial manufacturing capabilities to maintain (or extensive stockpiles)
* Wheel-based movement limits navigable terrains
Summarizing all this, the key "big value" in horse-technology is that it is a capability that you can maintain with an extremely low tech level and that they can go almost anywhere--on Earth horses can even survive in the (right) wilderness without any human intervention. That said, it is not an easy capability to maintain and requires extremely specialized knowledge to use horses: extensive know-how in training/disciplining, care, medical aid, operation, etc is required. Unlike the skills required to maintain a rover (or a car) these don't overlap much and require a long time to learn so you would need dedicated horse specialists who spend their full time dealing with horses (and grunt labor assistants who shovel shit and whatnot). Modern people generally regard horses in a rather abstract sense (an animal that carries people) but the reality is that horses are an absolute *pain* to deal with. They are ornery, spook easily, and are generally considered at the very edge of animals that are considered "domesticate-able" (see how zebras aren't).
Rovers--or self-propelled motorized vehicles more generally--don't benefit from the advantages of being biological life: no self-repair or reproduction. They *require* advanced manufacturing capabilities and a technological support system. This support system generally requires less skill and labor for an equivalent transport load, but that's because a lot of the effort involved has been "frontloaded": engineers have collectively spent man-hour-centuries (or more) developing the tools to make the tools and the designs that go into making the rover. This is how you can have a vehicle that can go tens of thousands of miles with basically no maintenance, and what little maintenance is required, can easily be done by someone "unskilled" with a week or less of instruction or a good instruction manual (oil change, wheel swap, etc).
So, unless you value being able to operate at a "zero" tech level, I would recommend technology based vehicles. Especially in a situation where resources are limited, the horse can easily break an ankle and become crippled for life while a modern, properly-designed vehicle can put up with a frankly ridiculous amount of abuse and still function better in almost all scenarios.
**TLDR: Rovers**
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This is my first question in the series "Saturnian Cloud cities". The second question is [Ice Harvesting planes](https://worldbuilding.stackexchange.com/questions/235907/saturnian-cloud-cities-pt-2-ice-harvester-planes)
My cloud-city is centred on a low altitude region just below Saturn's cloud tops, and it is lifted by a hot hydrogen balloon, which is heated by graphene cables that are many miles long and dip into the cloud tops to harvest geothermal energy from Saturn's interior. Electricity is harvested by massive wind turbines which spin under the intense hurricane-force winds of Saturn, which is then used for artificial lighting to grow algae and plants for oxygen and food.
The copper weights hanging at the bottom of the cables, weigh the airship down, which can be lifted barely by the hydrogen airship, but cannot be moved due to the sheer weight. And since copper and graphene are good electric conductors, the weights can transfer them to the cables. This would allow the balloon to stay still and not negate the wind energy.
Also, the cloud-city would have a launch pad for rockets to take off and land. And the population of the cloud-city is about 2,000 people, 3,000 pets, and 1,000 livestock creatures. Area of the cloud city is about 100,000 km2, approx. the area of Mudanjiang Megafarm
Can this concept for a cloud city on Saturn work?
A diagram for reference:
[](https://i.stack.imgur.com/AImIl.png)
Edit 1: So as to clarify some facts about my cloud city:
* The cloud-city is NOT floating in the water ice layer, instead it is just inside the ammonia ice layer, and let's just assume the rigid-hull balloon has some hydrophobic coating to prevent icing or damping.
* The geothermal cable doesn't stretch down entirely to the core, it is instead hanging just below the water-ice cloud deck, to get heated by the hot gases.
* I have edited the diagram to clarify the wind-turbine problem.
* The livestock consists of cows, goats and sheep
* The pets are cats and dogs, though you can add some fish or apes or even some exotic livestock like birds, if you want to.
* The mass of the copper weights are enough for the hydrogen to just barely lift, but not be moved
* Except for airships and some sophisticated equipment, the development of the people on that airship is just more than that of 2022 Earth i.e. they haven't discovered fusion, or some strange tech. But, they can launch rockets to its moons, like Titan or Enceladus
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There are a few issues with a city based on that design. A floating city will be pushed by the wind until it reaches nearly the same speed as the air around it. This would negate the use of wind turbines, as they would be traveling along with the wind at nearly the same speed. The city would need to be anchored in order to prevent movement, which would be impossible.
The balloon itself does not need to be suspended above the city. Simply encasing an area (similar to a snow globe) with a single atmosphere of pressure (1 bar) would prevent the city from descending beyond a certain depth as the external atmospheric pressure increased. “Water ice clouds begin at a level where the pressure is about 2.5 bar and extend down to 9.5 bar, where temperatures range from 185 to 270 K.” (<https://en.wikipedia.org/wiki/Saturn>) That temperature ranges from -126 to 26 F so insulation would be needed but water ice could be harvested. There is no need for a hot hydrogen balloon, just a single atmosphere of breathable gases. Depending on the size of your atmosphere, and the weight of the station construction material, you could design it to float at whatever height you desire.
As for energy, Saturn has a hot core, but that core is a heck of a distance from where a city would float. Dangling cables to pull heat up to the city seems silly, and would add tremendous weight to the city, when they could simply pull in hydrogen from the atmosphere and burn that in a generator. There are also trace amounts of fuel grade gases such as propane and methane, which could be captured for energy production. They could always send ships to harvest liquid hydrocarbons from Titan. If your world has discovered fusion power, then you have a nearly unlimited fuel supply floating outside your window. Fusion fixes most problems.
A city floating at a depth where water ice is abundant would potentially face the issue of snow and ice forming on its exterior. Ice would increase the weight of the station, causing it to sink further. There would need to be measures in place to prevent such a build-up. This could be something like a thermal mesh which overlays the surface of the station and keeps the exterior temperature just above freezing. The melted ice could be directed into collection points where it would be pumped into the station or simply be allowed to fall off back into the atmosphere. It could also be something as simple as small robots with RTGs which walk across the surface and melt the ice using their thermal radiation. I am sure you can figure something out.
Edit:
The temperature you are trying to capture would range from 80 F (300K) to 260 F (400K). There would be some loss as the heat going up the cable went through the colder regions of atmosphere. The hotter an object, the faster it radiates temperature away. It is unlikely that much heat would be able to reach the station after traveling through the miles of cable suspended in cold air.
As for your weights keeping the station in place, that would not happen unless they were dragging along the surface. Weight does not slow something down, friction does. This is why cars slide on icy roads, a lack of friction. The weight of the car remains the same. But listen, if you want it to work then just say it works. This forum is not designed to figure out new technologies or to brainstorm new ideas, but to answer direct questions. So to answer your question: No, this concept for a hypothetical cloud-city on Saturn would not work in reality… but it can still work for your story. For it to work the way you want, we would need to throw out physics. You can still tell an interesting story even if the world is not based 100% on hard science.
[Answer]
It is a napkin sketch, so not enough information.
Do you have star-trek level of technology and materials?
Where, in terms of latitude, were you thinking. Near the equator those winds are going at ~1000 miles per hour while comparatively small north-south changes can make that vary substantially. Up around 40 degrees it looks like they are relatively negative, suggesting that there may be quiescent regions that have adjacent less quiescent regions.
<https://solarsystem.nasa.gov/resources/11480/saturns-winds/>
Perhaps something that looks like a Phantom-Menace style pod racer, but done with wind turbines? On Saturn they would be extracting energy from the air, and sending it to the colony pod.
[](https://i.stack.imgur.com/8SUxP.jpg)
Here is what the ESA says about the atmosphere of Saturn, in terms of its depth:
<https://www.esa.int/Science_Exploration/Space_Science/Cassini-Huygens/Saturn_s_atmosphere>
The ammonia outer layer (ammonia is a great refrigerant aka material for phase-change driven powered heat transfer) is about -250 C, or about 25K, its very very very cold.
Just above the tropopause (130km in) it is about 0C, or merely ice cold. That is a big temperature swing, but it takes about 130km to happen. Near the core it is upwards of 11000C. A decent heat pipe, if it were strong enough, would be a plentiful energy source.
[Answer]
**I like the geothermal cables.**
Mostly because they would glow at night. ALso because deep Saturn beasts might sometimes bite one and tow the whole city around, like in Old Man and the Sea except on Saturn.
But @Gilgamesh is right in the comments - the Saturnalians would not perceive the fast wind because they would be moving nearly as fast. Turbines might not generate that much. That is OK. You can use your geothermal cables to generate electricity. People do that on Earth but unfortunately not with cables. Use the cables to heat a working fluid and then have the fluid turn a turbine.
I would like an electrical turbine that both generates electricity and captures heated waste gas for the balloon.
If you really want another system for electricity generation you could have the 1000 pygmy goats take turns on a treadmill. This will generate electricity and help them stay fit.
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[Question]
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My scifi world obeys the real world conservation laws. This presents a problem for spacecraft; due to the conservation of momentum, the spacecraft will need propellant, and a lot of it, for every single motion
However, I believe I have found a loophole in the form of negative mass. If I were to insert negative mass, and the ability to produce it, into my world then it seems like we could have a ship that can fly without energy: If equal and opposite masses are fired from opposite ends of the ship, then it seems like there would be an overall change in momentum (as momentum is directional) with no change in energy or mass (as they are scalars)
Could this work under the given rules? Or is this simply too good to be true?
[Answer]
# With negative mass things get crazy
* Mass is energy. If you can make negative mass, you're making negative energy. Since energy is conserved, that means you have positive energy "left over" that you can do whatever you want with
* With positive mass, pushing on it causes it to accelerate in the same direction (F = ma). But if the mass is negative, pushing on it means it *pushes back harder*. If you can touch a negative mass, it pushes against your hand, and the harder it pushes the more force there is to accelerate it into your hand ... while this sounds like a bad thing, [NASA says don't worry](https://ntrs.nasa.gov/api/citations/20200000366/downloads/20200000366.pdf), it'll fall straight through your hand because the Pauli exclusion principle won't work between it and ordinary matter. But I don't like it - there's still ordinary electrical charge on those atoms. I'll let *them* try it.
* The negative mass might neutralize the positive mass leaving nothing behind, which is one more reason not to handle it.
* A negative mass is pushed *away* from a positive mass by gravity, so it falls *toward* it. The positive mass is pushed away from the negative mass by gravity, so it falls *away* from it. [So you can build a ship](https://www.sciencenews.org/blog/context/fact-and-fiction-about-negative-mass) with a negative mass chasing a positive mass through space, accelerating indefinitely with no fuel consumption. The kinetic energy of the positive mass increases without limit, and the negative kinetic energy of the negative mass always matches up with it.
* Negative mass is also a sure-fire way to make stable wormholes, in case you want to get there faster. Most wormhole builders are looking for ways to *not* use negative mass.
In summary: yes, you can fly without energy - or make as much energy as you want - or get there without flying at all.
[Answer]
Different question, same answer, so I'll just reuse what I had writte for [Artificial gravity as an engine](https://worldbuilding.stackexchange.com/q/134187/21222)
As far as we know, any massless drive in space belongs to the realm of Troll Physics. Even NASA's EM drive. They all boil down to this:
However! Nature herself is the ultimate troll. Accept this as truth, and all boffinry becomes much clearer and easier to understand.
What you need in order to build an actual, scientifically accurate troll engine is antigravity.
[The Wikipedia entry on negative mass](https://en.m.wikipedia.org/wiki/Negative_mass) has this gem in it. The further you read, the more the troll nature of Nature becomes apparent:
>
> # Runaway motion
>
>
> Although no particles are known to have negative mass, physicists (primarily Hermann Bondi in 1957, William B. Bonnor in 1989, then Robert L. Forward) have been able to describe some of the anticipated properties such particles may have. Assuming that all three concepts of mass are equivalent the gravitational interactions between masses of arbitrary sign can be explored, based on the Einstein field equations and the equivalence principle:
>
>
> * Positive mass attracts both other positive masses and negative masses.
> * Negative mass repels both other negative masses and positive masses.
>
>
> For two positive masses, nothing changes and there is a gravitational pull on each other causing an attraction. Two negative masses would repel because of their negative inertial masses. **For different signs however, there is a push that repels the positive mass from the negative mass, and a pull that attracts the negative mass towards the positive one at the same time.**
>
>
> Hence Bondi pointed out that **two objects of equal and opposite mass would produce a constant acceleration of the system towards the positive-mass object**, an effect called "runaway motion" by Bonnor who disregarded its physical existence, stating:
>
>
> *“I regard the runaway (or self-accelerating) motion […] so preposterous that I prefer to rule it out by supposing that inertial mass is all positive or all negative.”*
>
>
> — William B. Bonnor, in Negative mass in general relativity.
>
>
> **Such a couple of objects would accelerate without limit (except relativistic one); however, the total mass, momentum and energy of the system would remain 0**.
>
>
> This behavior is completely inconsistent with a common-sense approach and the expected behaviour of 'normal' matter; **but is completely mathematically consistent and introduces no violation of conservation of momentum or energy. If the masses are equal in magnitude but opposite in sign, then the momentum of the system remains zero if they both travel together and accelerate together, no matter what their speed.**
>
>
> (...)
>
>
> Forward used the properties of negative-mass matter to create the concept of **diametric drive, a design for spacecraft propulsion using negative mass that requires no energy input and no reaction mass to achieve arbitrarily high acceleration.**
>
>
>
So there you have it.
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The idea of using negative mass to avoid physical laws is nothing new, but I assume you're not talking about FTL travel here? I think you'd first have to figure out where your unlimited source of negative mass was coming from, otherwise your ship is simply powered by unobtainium, and there are more sensible things to do with unobtainium. Rather than firing in two opposite directions, you might be better off creating a system which uses a negative mass drive to create localised regions of negative pressure which drive propulsion instead. Then your ship only needs half the amount of unobtainium...
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I'm afraid this is a no-answer, I'd like to post both a practical and a theoretical objection..
**Where to find material to build your ship, it will fly away from you..**
Suppose for now, negative mass actually exists. A galaxy could consist entirely of negative mass.. you'd only notice the void around it, it will look the same. In that galaxy, the negative mass would *attract* other negative mass, nothing would really change in the observation.
To let your propulsion work, you'd need both types of mass, you'd *only* have a ship built of negative mass, the rest of the world would have to be positive mass. Suppose it works (hand-waive hand waive) with a negative ship mass, how would you build that ship, in the first place.. I wonder where the building material for the ship is harvested ? You can't have a negative mass planet in your positive mass solar system. This planet would not stay near the sun, it would be in acceleration, moving 1000s of km/second away from you. Same with comets and meteorites. They won't impact on your positive mass planet, when their mass is negative.
**Double-sided space time ? a second antipode reality ?**
According to Einstein, the slope of a vector in space time will yield the perceived gravity at any point. The attractor resides somewhere "down", everything falling in the direction, along the gradient. We visualize heavy things as a "steep hole" in a 3d plane, the bottom being a stable point.
Now suppose you would model negative mass as the opposite: a steep hill in space time. Everything that sits on top of that hill will be *unstable*, prefer to move away from it, in any downward direction ! The ship will not move away from the planet, it will move toward the planet with even larger velocity. Conclusion: a steep hill does not work, to model your ship.
Instead, your ship would be on the opposite side of space time. You need a mechanism to *climb up hill* in our space time.. That would only exist, if our space time has an opposite, mirrored reality, on the other side, where the same gradient is perceived as *go down hill*. How *separate* would these two realities be ? And suppose you reside inside the ship, are you still in your world, or did you enter the antipode side of space time..
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[Jormungandr, the Snakebot of Doom](https://worldbuilding.stackexchange.com/questions/76425/escaping-the-snakebot-of-doom), has left the rubble of New York from where it has just finished destroying all the world's petroleum refineries and metal smelters, and has just made a right-hand turn in the New York suburb of Mount Vernon that puts it on course for Boston. As it has coiled itself into a billion-and-a-half ton hoop and is currently rolling toward Boston at around 75 kilometres per hour, Bostonians have three and a half to four hours before it arrives, and presumably begins steamrolling the city flat, much as it did to New York.
If Bostonians were to be informed by the [Emergency Broadcast System](https://en.wikipedia.org/wiki/Emergency_Alert_System) within minutes of Jormungandr's setting course for their city, how many could be expected to escape from a nearly 8km-wide swath of total destruction across the most built-up part of Boston? They have three and a half to four hours before Jormungandr arrives, plus whatever time it takes to reach their location at its city-destroying speed of about 5 KPH.
Jormungandr is really only going to focus on steamrolling buildings 3-4 stories or taller that are among other such buildings, or individual buildings of 6 stories or taller unless they are a long way from other target buildings. Buildings 24 stories or above will be targeted regardless.
More importantly, how can I work out for myself how many people might be evacuated from a given area of a city, given an amount of time to conduct the evacuation?
Jormungandr is probably going to flatten a swathe about 7.5km wide from Roxbury in the south to Revere in the north, including the University of Massachusetts and Boston Logan International Airport in the east (but not the runways, and maybe not the terminal buildings either), to Harvard University in the west, that area containing most of the large buildings. It will also include a 400m wide track coming in from the south-west, and leaving to the north-west. However, Jormungandr has not announced these plans. All that is *known* is that it appears to want to flatten large buildings.
For my Juggernaut stories so far, look at <https://medium.com/@MontyWild>. Chapter 5 describes Jormungandr's attack on New York City, which would likely be much like its attack on Boston.
[Answer]
**Most of Them.**
[](https://i.stack.imgur.com/mAvCZ.png)
People have nearly 4 hours to escape. If they get out of bed, pick up their babies, and start walking at the relaxed pace of 3kmh they can get 12km before the Snakebot of Doom arrives.
Since the Ravine of Destruction is only 8km wide they can move out of the way in time. If they move in the right direction no one is more than 4km from the edge of the ravine, so they can get 8km from the edge.
The big trouble is a stampede of people coming one way blocking a stampede coming the other way. Perhaps this can be coordinated using public radio, which tells which suburb which way to run. It is already good at redirecting car traffic after all.
Then it is a question of (a) how long the snake takes to turn around. Since it is so big I guess this will be in the hours. Then there is (b) where do these people go next? Without the infrastructure of an entire city to provide water and shelter they will not survive long exposed to the elements.
*Photo is from 2005 War of the Worlds.*
[Answer]
Sadly, only a 5% of the people made it out. All the major highways were blocked by people waving banners saying things like:
Don't be a sheep! Jormungandr is a lie!
Jormungandr is fake news! THEY are using fear to control you.
Patriots don't run!
Why are you afraid. Jormungandr only killed 0.000001% of the people in the world.
My faith and freedom are stronger than any snakebot!
[Answer]
**All of them.**
Because the people were not waiting for the sirens signaling 3.5 hours to bigsnake arrival. Washington DC and many other world cities were hit by nuclear bombs on Jan 20 2 days prior. It is big news, this. The government of MA knows Boston could be next. And the citizens of Boston are not fools either. They do not sit around scratching themselves, or at least they do less than usual. They know they will be safer outside of the city and as soon as the news is broadcast that is where they head. The roads and rails are choked with fleeing people even before the snake makes landfall and gets to work in NYC on Jan 21.
Many residents of urban Boston do not have private vehicles and the evacuation / exodus is complicated by snow. Nevertheless with 2 days advance notice Boston is empty except for a cadre of snake worshippers when the snake shows up and rolls around. Loss of life from the approach of the snake through the suburbs is matched by loss of life in the chaos of the flight from the city.
In the panic, Atlanta ultimately loses more people than Boston and the snake does not even get down there.
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I imagined that in the far future, humanity has become space-faring and is running experiments with seeded worlds. One of these planets would be an earth-sized moon with almost identical atmosphere to Earth (I know it's not likely).
Unlike the other seeded world however, the only multicelular lifeforms on this world are plants and fungi. As millions of years pass, would any 'predatory' plants evolve?
[Answer]
# Not predatory, parasitic.
[](https://i.stack.imgur.com/PWxPd.jpg)
The picture above is from a plant called *Cuscuta racemosa*. The thing that makes this plant interesting is that, despite being a plant, this thing is an obligatory parasite, aka it can't survive on its own, and must feed on the sap of other plants in order to survive.
Truth is that when it comes to plants, predator prey relationships aren't like we'd see on animals. An attacking plant can take its sweet time approaching another one, because plants aren't nearly as mobile as an animal, nor can they unroot and re-root themselves whenever, so unless we're talking about an extreme exception, the plant being attacked isn't going anywhere. Because of this, the closest you can get from a "predator" plant is a parasitic plant. *Cuscuta racemosa* is a more extreme example because, unlike some other plants who also engage in parasitism in order to save their own resources, this particular plant has completely lost the ability to survive on its own, and is probably the closest you'll get from a plant that hunts other plants in terms of "diet".
As for the closest you can get in terms of behavior, look no further than the [dodder vine](https://www.npr.org/templates/story/story.php?storyId=6160709), also known as strangle weed. This leafless parasitic plant has an almost animal-like behavior, in the sense that it finds its preferred "prey" through smell. Not only that, it has preferences in the sense that they will choose some plants over others through the smell each emits. It's theorized this plant "hunts" by literally growing towards the source of smell, which they identify through special chemo receptors, in a likely example of chemotropism. Once it reaches the host plant, it starts to wrap around it as it grows and begins its pararitism.
Regarding how we found out about that, we tested if it found the plant through smell, and found out it did.
>
> When the researchers isolated tomato plant odor chemicals and smeared them on a piece of rubber, dodder tried to attack that. Seventy-three percent of the seedlings headed toward the piece of rubber with tomato chemicals compared to a plain piece of rubber.
>
>
>
So summing up, if by predatory plants you mean a plant that actively moves around like an animal made of leaves a and vines and goes eating its relatives left and right, then likely no, you won't get predatory plants without some serious handwaving. If however you're fine with a less active, but more realistic equivalent of a predator-prey relationship between 2 plants, then absolutely you can. It will however be ultimately considered as a type of parasitism, simply because plants aren't nearly as dynamic as even the slowest of animals in terms of needing move around from place to place.
[Answer]
**Vegetarian sundew.**
<https://www.cpukforum.com/forum/index.php?/topic/61472-vegetarian-sundew/>
[](https://i.stack.imgur.com/7KSYKm.jpg)
>
> Vegetarian sundews: Few people know, that carnivorous plants like also
> vegetarian diet, as long as it is rich in protein like flower pollen.
> To show this, we fed fresh stamens of a Sarracenia leucophylla with
> adhering pollen to four different Drosera species (photos). D.
> capensis and D. ultramafica rolled in the leaf as intensive as with
> animal prey.
>
>
>
I was thinking about the predatory plant the [sundew](https://www.nwf.org/Educational-Resources/Wildlife-Guide/Plants-and-Fungi/Sundews#:%7E:text=Sundews%20are%20%E2%80%9Cflypaper%E2%80%9D%20plants%20that,the%20sun%2C%20thus%20their%20name.&text=These%20plants%20feed%20on%20insects.). Sundews live in nitrogen poor soil and supplement their nitrogen by catching insects. But what if they caught nitrogen rich plant matter? I was thinking seeds but these folks tested it with pollen and the sundews liked it.
On your world there could be plants which consume mobile parts from plants and fungi like seeds, pollen and spores. These parts are nutrient rich because they are supposed to give rise to a new organism and so perfect for a predator to eat.
I am thinking now about a riff on sundews - if a piece sticks to a seed but the seed "gets away" - maybe it is blown or washed away - the piece of sundew goes with it. It can regenerate the sundew parent plant but now in the context of this great big tasty thing that blundered into it, which will jump start the plant.
Maybe human explorers will brush into one of these seed-eating sundews and have them stick. They think they have pulled them off. But some is left behind.
[Answer]
Plants and fungi are more closely intertwined than most people realize. Most plants have strands of fungi, called mycorrhizae, growing on their roots in a mutualistic relationship. The fungi increase the plant's access to water & minerals, and in turn take nutrition from the plants. (The associations can be much more complex than this, too: the mycorrhizae can pass nutrients between species, increase resistance to insects & disease, and more: <https://en.wikipedia.org/wiki/Mycorrhiza> )
An interesting example of a plant that takes advantage of this relationship is the Snow Plant (Sarcodes sanguinea). It has no chlorophyll itself, so is a parasite/predator on the mycorrhizae of pine trees, and indirectly on the pine trees themselves. <https://www.fs.fed.us/wildflowers/plant-of-the-week/sarcodes_sanguinea.shtml>
[Answer]
>
> the only multicellular lifeforms on this world are plants and fungi
>
>
>
neither of them is mobile, and carnivorous plants on Earth evolved to integrate their element supply by feeding on mobile targets.
The only "predatory" style that plants might evolve in your case is to prey on other plants, in the sense that their seeds, carried by wind or water, would use other plants to grow. Sort of what the mistletoe or the straggling ficus do on Earth today.
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An omnipotent but not omniscient or omnibenevolent deity has decided that creating an evil looking moon that works according to natural law would be a great addition to their world's mythology.
[](https://i.stack.imgur.com/CF2ww.png)
They want it to be as dramatic as possible, and their power budget is effectively infinite. Evil looking face, glowing eyes, anything that makes the moon look spooky and sinister. However, they're not sure how to make sure the moon keeps looking evil in the long run, even if they leave and go off to do other things.
They are not omniscient. They have immense knowledge and intelligence, but not perfect future prediction. While they can reshape the moon as desired, and do anything within the laws of physics, biology, or chemistry, creating some sort of endlessly lasting magical or technological construct or illusion that lasts forever is beyond them, as is a perfectly ordered intelligent civilization that will do exactly what they want to maintain a magical or technological construct forever. Ideal answers will rely on mostly natural causes for the spooky moon face, but will be durable enough to last a few thousand years without maintenance.
[Answer]
Large impact craters will define the shape of eyes and evil grin. In the eyes the central rebound peak will even give you the pupil. For the grin in particular, you just need a stripe of suitably aligned craters. Our remarkable pareidolia will ensure that we will see a face there. [We already do](https://en.wikipedia.org/wiki/Man_in_the_Moon).
Then, to increase the dramatic effect, cover the areas you want to be red with generous amounts of iron oxide. Mars is known as the red planet for good reasons, it has been associated to war because of its bloody color.
For bonus evil appearance, you can set up cliffs that with certain angles of incidence will look like faces, sort of what happened with the famous face on Mars. That might help when the moon is not yet full and sunlight is more grazing.
[Answer]
Just painting the Moon should last for a few millennia - just make sure to use UV resistant pigments.
Otherwise, mini-impactors creating craters of 0.1-1km radius (will show as a darker shadow, due to the direction in which the slopes of the crater will reflect the light) and using [dithering](https://en.wikipedia.org/wiki/Dither) to create the image. These are bound to last for millions of years at least.
Dithered, it may look like this (it'd be nicer with deeper black eye sockets, but it they can't be made black under all angles of illumination. Unless you paint them black, that is)
[](https://i.stack.imgur.com/tWyn7.png)
[Answer]
**No Rounded features**
Big round eyes and round face are the signs that our instinct identify as belonging to children and trigger protective behaviour. They would not appear so threatening. So your moon should be smaller than the mass that would push an object to get a perfectly spheric shape, something like [Vesta](https://en.wikipedia.org/wiki/4_Vesta). In order to be visible it should orbit quite close to the planet.
For some geological reason the satellite is made by a bright reflective material covered by dark carbonaceous chondrites. Two obliquous impacts would exposte two narrow strips giving te appearence of narrow eyes.
With the other irregularities of the surface appearing as scars on a face you won't need a grin, those two eyes constantly staring from above would be threatening enough.
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In my story, a group of scientific explorers go on a expedition to a planet, and I am not sure if it should be a super continent or multiple continents because of the diverse life there could be on a planet. There are deserts, forests, savannahs, and mountain ranges with snow. Would creatures be as diverse in these if it was all connected or across oceans on different continents or would it not change as much as animals on earth became diffreant species when they went to other continents or islands. For those wondering, the continent lays on the equater of the super earth.
[Answer]
While oceans make very effective isolation mechanisms, there are others. This will be not so much the physical effect of, say, very high mountains as the incompatibility of habitats.
As a plain grows colder, the farther it gets from the equator, the fauna and flora will shift. Perhaps clinally, so that in theory genes could pass from artic to tropical regions, but the tropical and artic subspecies could not interbreed directly.
Then there are difference of the habitats such as grass grazers who can not live in the swamp because the footing is so uncertain, and arboreal monkeys that can not leave the swamp's trees for the grassy plains.
An enormous variety is possible.
Note that two forests may be effectively "islands" because of the expanse of the grassland between them -- or vice versa. True, plants and animals will occasionally cross, but that happens on islands, too.
[Answer]
You don't need to look very far for a real life example. Only a few thousand years ago you could (with some minor humping over ice and a brief swim) walk the majority of the way around the planet from South Africa to the southern tip of South America, from 68 degrees South to 77 degrees North. Even considering only the present day, Africa/Eurasia forms what is by any measure a supercontinent that is 14,000 km from the Cape of Good Hope to the Taymyr Peninsula, and 14,600km or so from Dakar to the Bering Strait, and has been in essentially that position for 30 million years. Yet no shortage of diversity in climate, ecosystems, or biology.
[Answer]
Sure. Even if a Pangea like continent complicates a bit the atmospheric circulation and the precipitation distribution, you still have differences in elevation and solar irradiation which account for variation in local climate.
With different climates come also different life adapted to it.
[Answer]
It depends on what kind of diversity of life you are talking about, and exactly where your super continent lies on the planet - ie, does it straddle the equator, or does it run north to south, etc.
We have gotten very unique species of animal for isolation in places like Australia, or of course, the classic example of the Galapagos islands. As has been mentioned by the others here, mountains, other landforms, and just distance in general can bring about biodiversity. If you are not aware of it, I recommend looking at the Youtube series "Alien Biospheres" by Biblaridion, as it is fantastic, and part of his imagined history on an alien world is on a super continent.
For a less scientific example for what you can do with a super continent, I recommend looking at Brandon Sanderson's Stormlight Archive, which takes place on the stormswept super continent of Roshar, and has amazing biodiversity. While the very large series is fantastic, this video gives a great introduction to what you'll find more useful in making an interesting supercontinent:
(Invicta, Welcome to Roshar | The Stormlight Archive - Lore Primer)
<https://www.youtube.com/watch?v=xL4M7Yx0SSE>
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[Question]
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Four warring countries sign a compact to cease aggression.
The compact establishes a city to act as neutral territory for economic and foreign policy meetings. The city has an independent government for internal matters, but it's dependent on the signatories for defense, funding, and most of its population.
What term describes such a region? In other words, what geopolitical word or phrase is at the Venn diagram intersection of
1. a specific term for
2. a populated area with local autonomy, which is
3. created by more than two states?
If possible, please provide a reference to the definition of the term you suggest so that it's possible to confirm the term describes this scenario.
I've considered the following terms, but I'm not sure whether there are others that better match the criteria I've laid out above:
* buffer state
* city-state
* compact (this is not an established use of the word; this invented use would be a nod to the compact that created the region)
* protectorate
* territory
[Answer]
I think a formal term for such an entity is "autonomous region". Since this one is created by multi-party treaty/compact, it might be referred to as "the XYZ neutral autonomous region" where XYZ is the name of the treaty.
[EDIT] Some comments on some of the other possibilities:
* "buffer state" is the reason for its existence but not a description of what it is, in a legal sense.
* "city-state" and "territory" are unspecific. Both descriptions apply to this entity but those terms apply to many other entities.
* "protectorate", "codominium", and some of the other suggestions implies a significant level of outside direct rulership and the querent says that it is self-governing. The entity may have legal obligations to the nation-states that created it (e.g. neutrality, not creating a military) but those can be handled by having it be a party to the treaty or directly writing those terms into its charter/constitution.
* "DMZ" doesn't really cover this entity's being inhabited and being self-governed.
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## Condominium
No, not a posh downtown apartment close to work and the shopping district, but rather a [political condominium](https://en.wikipedia.org/wiki/Condominium_(international_law)) -- a location where two or more polities share coordinated and equal dominion.
Such places do exist in reality and are places where your four warring states would exercise external control but where internal policy could be regulated by the local authority. The specific nature of the condominium would depend on the nature of the agreement signed by the four powers. Some real world condominiums divide rule over the place by season (there is a place where for six months it is France and where for the other six months it is Spain (and where for twelve months out of the year it is *not* Andorra)).
## Demilitarized Zone
Panmunjom / Truce Village. The border between North and South Korea. Famous for being the spot where President Trump set foot on North Korean soil.
This is a place where your four powers meet but do not post troops. All their armies are kept at a discrete distance from four-corner-stone. In this scenario, the city itself governs internal affairs but remains part of the four countries politically.
## Bir Tawil
Terra Nullius. The only truly [unclaimed piece of land](https://en.wikipedia.org/wiki/Joint_Security_Area) on Earth. This is a curious piece of land whose status exists because Egypt and Sudan each have different ideas of what their mutual border should look like. In a nutshell, Egypt likes a nice clean straight border (established in 1899) and Sudan likes the administrative border (established in 1902). This means that, according to Egypt, Bir Tawil is not theirs, and according to Sudan, Bir Tawil is ... um ... not theirs ...
Just multiply the situation so that accepted borders and claims over the region leave the desired area unclaimed. [Much like Luxembourg](https://www.youtube.com/watch?v=c-WO73Dh7rY&t=9s). Being in the middle of four warring states, they won't have much choice but to accept an external defense & trade arrangement; and because none of the four warring states claim it, its internal affairs are governed locally and can act as a neutral meeting place.
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So, much like (unworkable) [Jerusalem](https://en.wikipedia.org/wiki/Corpus_separatum_(Jerusalem)) or (functioning) [West Berlin](https://en.wikipedia.org/wiki/West_Berlin) (and somewhat less similar Danzig, Fiume, Trieste) and [UN trust territories](https://en.wikipedia.org/wiki/United_Nations_trust_territories), or before that, [League of Nations mandates](https://en.wikipedia.org/wiki/League_of_Nations_mandate) in our history? Borrowing the terminology, a *mandate* or *mandate city* or *trust city* would be a good choice; or even Free City of [city name].
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Honestly, I suspect this region will eventually develop three names:
* An official name based on the treaty that created it. This is what will be used in all official international documents regarding this territory
* A semi-formal name used by each country based on how they perceive the carved out neutral zone, and tuned to their own language and ideals
* A common name/title that the new state will develop as people start making a home in the new state and it starts developing its own unique identity. This could be a name that possibly organically develops or it could be decided upon by the new natives of this city.
Each of the three names is a nod to the worldbuilding around it, though I suspect you are looking for tips on the formal name of the territory. The first thing is that it probably won't be officially known as a full country or state in the treaties that create it, that much is fairly obvious based on the question itself. I also would think that what they call it will be based on the official names of the four signatories to this treaty.
In fact, the very title given to this territory could be a point of contention for the four nations due to their differing viewpoints on the matter as well as intricacies in language and official names.
A new in-world term might even be invented in-world to handle this such as a **Minor State** or **Lesser State** to denote that it has some sovereign rights but not all the rights the four signatories of the treaty have -- or any other full nations of your world for that matter. The term **City-State** would be fairly accurate as it sounds like your four nations have carved out a city (and likely a buffer zone for said city to grow into) as the neutral territory. It is also neutral and descriptive as to what this new territory is.
In the end, consider what the four states would like to call this city, and see if there is either a (surprising) agreement on what title to give it, or if there is a title to give it that would be acceptable to the factions involved in its creation, even if you have to make it yourself and not use something established as a term in our world.
If it helps, here is a link of [official country names](https://worldpopulationreview.com/country-rankings/official-names-of-countries). I have noticed that most of them have Republic or Kingdom as part of their official name somewhere, but even official names are not universal.
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[March](https://en.wikipedia.org/wiki/March_(territory)) is such a term. It is an independent County but where the Count is styled at the level of a Marquess.
For instance Barcelona was the seat of the [Marca Hispanica](https://en.wikipedia.org/wiki/Marca_Hispanica), and Berlin was the capital city of the [Margraviate of Brandenburg](https://en.wikipedia.org/wiki/Margraviate_of_Brandenburg).
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How far would 2 tidally-locked (to eachother) planets need to be from their blue star host to be habitable, but have a cold-weather climate similar to our Ice Age?
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**TL;DR:** binary planets probably handwaveable to be OK, iceage climate can also be arranged. **Making a habitable world around a blue star is basically a non-starter**, though. Too hot, too bright, far, far too much UV. You should probably change that.
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It is difficult to say exactly how the climate of a binary planet will differ from the situation on Earth... the day length will be longer, and so the days will likely be warmer and the nights colder. It is *possible* that some [atmospheric super-rotation](https://en.wikipedia.org/wiki/Atmospheric_super-rotation) will help even things out... strong prevailing winds will help warm the night side and cool the day side to some extent.
Having an ice-age like cold weather climate is easy though... just slap em in the habitable zone and call it a day. After all, Earth has been both [ice free](https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum) and [entirely frozen over](https://en.wikipedia.org/wiki/Snowball_Earth) in its time, without having any kind of dramatic orbital change. Just handwave in your desired conditions, and you'll be basically good to go.
The habitable zone of a blue star is a bit more awkward, though. There are multiple problems with having such a hot star as the primary, but I won't cover them all here. Lets consider a a star like [18 Tauri](https://en.wikipedia.org/wiki/18_Tauri). It is a main sequence B8V star, so it is quite small and cold by the standards of the some hot blue stars. As you can see from the Wikipedia page, it is larger than the sun... nearly triple its radius. Its luminosity though is more like 160 times that of the Sun. Its surface temperature is over 13000K. That's pretty hot and bright.
In order to receive about the same amount of [solar irradiance](https://en.wikipedia.org/wiki/Solar_irradiance), your worlds might need to be a factor of $\sqrt{160}$ or more than 12 times further away from the star than Earth is from the Sun (this is a *very* lazy approximation for a habitable zone, but it'll do as a starting point). That gives your star, as seen from your worlds, and [angular diameter](https://en.wikipedia.org/wiki/Angular_diameter) of about 0.12 degrees. Compare this with the Sun's apparent angular diameter of more like 0.52 degrees... your star has a quarter of the diameter and so a *16th* of the apparent area. It'll look like a tiny, blindingly bright light in the sky, producing hard-edged shadows. It won't look like a cool blue version of the sun. The very blue-white light will make everything look quite washed out and sterile.
That's just aesthetic though. More concerning is the nature of its radiation. . The sun, with a surface temperature of ~5778K, has the [peak of its radiation spectrum](http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/wien3.html) at 510nm, a faintly bluish green, and only about 3% of the total output is of UV wavelength or shorter. 18 Tauri has a peak at 210, which is hazardous and destructive [UV-C](https://en.wikipedia.org/wiki/Ultraviolet#Subtypes). More than 20% of the total radiated output is vacuum UV, and nearly 50% of the output is any kind of UV (or worse). (Worked out using [another handy calculator](http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/radfrac.html) on hyperphysics)
This will be exceedingly destructive to pretty much anything made of chemical bonds. The oxygen in your atmosphere is particularly good at absorbing UV (that's what the ozone layer does on Earth). The increased rate of oxygen-bond splitting increases the amount of high-altitude monatomic oxygen and ultimately atmospheric escape. Your atmosphere will be rendered unbreathable much more quickly than it will on Earth.
Even if you handwave that away things will still look very weird and alien... plants won't be green. I'm not sure quite what colour they will be, but I could imagine a white or black might work. It will look *very* alien indeed.
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One very well studied planet, the planet Earth, has a distance from its star, the Sun, which is exactly 1 Astronomical Unit (AU) by definition.
You ask for climate like Earth had during the Ice Age, which was really a bunch of separate ice ages, separate glaciations. In those glaciations Earth's average temperature was a little lower than now, and glaciers covered a much larger percentage of the surface than now, and the lands at the edges of the ice sheets were (obiously) not warm enough to melt the ice very vast when the edge of the ice was advancing or when the edge was standing still.
Those events happened when Earth was at a distance of one AU from the Sun. And as I rememeber, during the last one or two million years the glaciations have been much longer than the interglacial periods like the one we are now in, though the maximum extent and peak of the ice lasted for a much shorter period than the total period of each glaciation.
So Earth's ice ages happened when Earth received about as much energy from the Sun as Earth receives now.
And before the last million or two years ago there was a period of tens or hundreds of millions of years with no glaciations on Earth, even though Earth received about the same amount of radiation from the Sun then as it did during glaciations and as it does now.
You should study the various theories about the causes of Earth's glaciations and see how well you can give your planet similar contributing factors.
<https://en.wikipedia.org/wiki/Ice_age>
Since Earth is now in a state of recurring glaciations, you should calculate what I call the Earth Equivalent Distance (EED) of the star, the distance at which the planet receives as much energy from its star as Earth receives from the Sun, and put your planet at that distance from its star. That should be enough to explain the glaciation the planet is currently experiencing, if you can also give the planet the factors which contribute to the onset of glaciations on Earth.
I note that during the glaciations on Earth, the lands adjacent to the ice fields and at high altitudes were quite cold, but there were vast regions near the equator which were quite warm and lush.
I don't know if that is acceptable to you. Maybe you want most of the planet to be covered with ice caps, and the small regions of bare land and sea to be cold and occpupied by cold wether plants and animals.
In that case you might need something more like the periods of snowball Earth than like ice ages.
Periods of snowball Earth supposedly lasted for millions or tens of millions of years and happened several times in Earth's history.
I note that astrophysical calculations suggest that the Sun slowly and steadily gets more luminous, and so it seems an obvious guess that the end of a period of snowball Earth might result from come the amount of radiation Earth gets from the Sun increasing past a critical tripping point. But that could not explain several different periods of snowball Earth separated by warmer periods.
Thee sems to be considerable uncertainty about the causes of those snowball Earth episodes.
<https://en.wikipedia.org/wiki/Snowball_Earth>
Both the current period of alternating glaciations and interglacial periods, and the periods of snowball Earth, are examples of Earth during icehouse periods. The climate of Earth seems to have alternated between greenhouse and icehouse periods over geologic time.
So possibly some of the icehouse periods in Earth's past may have been better for your purposes than either the more recent glaciations or the more distant snowball Earths.
<https://en.wikipedia.org/wiki/Greenhouse_and_icehouse_Earth>
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**Goldilock- or habitable zone**
For each type of star, there exists a certain minimum and maximum distance for planets, that could support fluid water. When your Ice Age would be anywhere earth's, you'd still have fluid water.. so when these planets are both Earth-like, you could put it at a position comparable to Earth, but not closer.. Earth is actually quite hot.. on the inner edge of Sun's habitable zone, which is 0.95 AU[\*] wide. You could put your planet e.g. where Mars is, in the middle.. 1.524 AU from the Sun.
<https://physicsworld.com/a/earth-is-closer-to-the-edge-of-suns-habitable-zone/>
**Atmosphere**
If Mars would have an Earth-like atmosphere, you'd get a lot of snow and ice. With a denser atmosphere, planet Mars could become Earth-like, or an ocean planet.
**Double planets**
This planetary system of yours better be stable ! For climate, I see only one effect between the planets affecting temperature. Size matters.. if your 2 planets are close and differ considerably in size, the smaller planet gets periods of solar eclipse, which can cool things down. But apart from that, atmosphere and sun-planets orbit distance is the key to get an icy, inhabitable planet.. they could have 2 different atmospheres, one -70 degrees Celcius and Mars like, the other Earth like.
[\*] AU = Sun-Earth distance
NOTE: this explanation ignores the fact that we have a blue star. As Starfish Prime has pointed out, these are quite hot and emit deadly radiation. There *could* be a goldilock zone (supporting water) however it may be doubtful there is a habitable place on these planets, unless its inhabitants are very resistent to radiation.
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I am going to focus this question on the US, but I would love an answer that also includes the EU, or even the world.
Let's say we have a secret organization. Something like the MIB or the SCP Foundation, set in the modern day. Let's say they have effectively limitless resources, and can compromise or are supported at the highest levels of government. To make it easy let's say the US President is aware of and supports the organization.
How could these members be given clearance and the ability to request cooperation from any other government or law-enforcement organizations with minimal questions asked?
The goal here is to give someone access but involve as as few people as possible in the conspiracy. For instance, MIB badges would be out, because normal people would not know what they are.
FBI badges may be better, but would they open enough doors? Would police departments try to verify identities and many people in the Bureau would need to be in on the conspiracy to make any public inquiry not instantly reveal that these are not real agents.
I would also assume FBI means little to the US armed forces. The CIA may carry more weight, but the CIA does not carry badges. Their credentials again need to come from other sources.
So what would be the best, cleanest, way for a secret organization to set up its agents with all necessary power, but few channels to follow back?
Also, no mind erasing tech is available. We have to use what we have right now.
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The problem with "fake" credentials is: Even if they are essentially the real thing, a "real" FBI agent would probably notice that something is wrong, because "I never saw you at headquarters" or "How come you do not know this thing we learn in basic training?" It is extremely difficult to pose as a FBI agent if a real FBI agent is around, and your cover needs to hold for more than one or two hours.
So, camouflage by no camouflage. That is, give a bunch of your agents FBI badges and FBI training. And offices within a FBI building. For other FBI agents, they are just another department within the FBI. Maybe it is not exactly clear what they do, but the FBI has so many different levels of security clearances and things that are on a need-to-know basis that one more "Sorry, I can not tell you what exactly I am working on" is not suspicious. If your secret agents "pose as FBI agents" no one will notice. They *are* FBI agents.
Do the same at the CIA, the NSA, homeland security, and so on. Now, when you need someone to appear as a "figure of respect", just choose someone who can pose as a member of the organisation which is most useful in this instance.
I would stay away from handing multiple badges to the same person. Imagine you are a legitimate FBI agent. And there is this other woman, who claims to be a higher ranking FBI agent. You never saw her. She doesn't know about this one instructor at basic training, whom everyone remembers. And then, you accidentally see that she has badges from six different government organisations. I would contact headquarters and ask them to confirm that woman's identity. I would ask them to check whether there is any possibility that the badge was stolen and is used by a sibling or look-alike. I wouldn't rest until I figured it out. That is too dangerous for your organisation.
[Answer]
**You Need Sideways Access**
The US intel community (and most intel communities for other major powers) are big in theory, but widely distributed into small groups. The FBI, for instance, only has about 60,000 people in it. What's more, each individual office has it's own territory, and crossing from one Area of Responsibility into another is a faux-pa at best, and a serious policy violation at worst. The individual offices are small enough (from a few dozen to a thousand-odd, and that includes "non-agent" staff) that everyone knows everyone. So your fake FBI employee would have to pretend to be from another office. BUT the further you get from the area's actual office the more suspicious it becomes, while conversely the closer you are the more likely you are going to blow it via not knowing who you should know. (ie: somebody claiming to be from the New York Office in the LA office's territory is going to raise a trillion red flags. Someone claiming to be from San Diego's office will raise a couple dozen red flags, and might get burned because agents from LA will know many agents from San Diego.)
Instead, I suggest two things:
1: Get your agency Universal Database Access. The USG has hundreds of databases with bespoke access. This one only the FBI has access too, this one DIA uses, this one CIA and TSA use but FBI has no access. This one FBI and DEA have access to but CIA doesn't, this one only state and local law enforcement have etc etc etc. However "read only" access would be trivially simple to set up, and would resolve 90% of your potential problems. After all, you don't need access to a CIA office if you can already see the recordings the CIA made and documented in their file! (this obviously wouldn't work as well in the 80s. But that just gives you some hand-wavy "back in my day" talk from older MIB Agents about having to fake being DEA Atlanta to send a file request to DEA New York and then intercept it etc etc. But nowadays everything is digital which means your life is easy!)
2: If you are out and about and run into, say, a DEA agent, you don't show them a DEA badge. You show them a FBI badge, or an ICE badge, or whatever. Which depends on circumstance. Some agencies have excellent "no questions asked" relationships with other agencies, either nationally (Say maybe DEA and FBI work well together all over, but the DEA HATES some other agency and only helps them grudgingly through formal channels) or at an office level (Maybe the FBI and CIA don't get along, but the New York FBI office gets along well with the CIA because of "reasons". Or maybe the CIA and FBI work great together EXCEPT the NY FBI office.) If you train YOUR agents in these sorts of byzantine quasi-political trust systems, you can easily get tons of cooperation without risking mis-steps based on not knowing a person's name you should or not knowing a normal bit of agency trivia.
As a sidenote, small obscure organizations are also great to fake. The Small Business Administration has a dozen-odd "Special Agents" that technically have all the investigative powers as FBI agents, but specific to SBA-related crimes. Faking one of these guys with a humble attitude could easily get you "in" with more "prestigious" organizations, as even a high-ranking FBI person is unlikely to know anything about his supposed equals in the SBA!
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**Have the motives of the organization be secret, not the organization itself.**
Do we really know what the CIA does? Or even the FBI for that matter? Sure, we have an idea, or we think we do. But how do we know there aren't secret motives revealed to a select few within those organizations where they're carrying out all sorts of objectives that we, the public at large, would totally object too? As a matter of fact I'd bet they are!
So, you're guys are actually real NSA, CIA or FBI agents, but secretly they're doing what you need done in your story.
Also, Interpol and the United Nations are things.
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If this secret agency is condoned by the federal government (United States) at the highest level, it has official sanction.
The US government already has procedures in place that allow other secret agencies to do essentially what you're asking. A call is made, a sheriff or a police chief is told people will be coming by, that they need the full cooperation of the local department, and even maybe that they will be taking over the investigation because of its sensitive national security nature.
This isn't the stuff of fiction, but is real. The name of the agency itself is in some cases not revealed. Explanations aren't necessarily given, or if given, aren't necessarily true. There will be no need to show badges or identity documentation. If they require someone to be arrested or warrants to be served, they will task the local police with that (or may even pull in the FBI to handle that part). Only afterward would the "suspects" be rendered from the jail to a facility where they had access (so-called black sites).
If the agency isn't officially sanctioned, it's unlikely they'd be able to operate in this manner without being investigated themselves in short order. (With either FBI counter-intelligence investigating if they were believed to be a foreign agency, and some other FBI unit if they were believed to be domestic. The feebs would even possibly get help from the CIA or other agencies if it was believed that they had something to add, but inter-agency cooperation is still rather abysmal.)
As for official sanction, the president could only operate in this manner for a few months before he pulled in the House and Senate intelligence committees. Otherwise, he risks them becoming aware of it, and depending on how they view this executive sanction, possibly impeached. However, if made aware of it and convinced of the urgency of the mission, it could then proceed indefinitely without ever requiring public and official recognition of its existence.
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How plausible is it to have zinc-sulfur as the main propellant of a gun in the absence of better ones, like gunpowder and smokeless powder?
If it isn't possible, is there a weaker, less effective alternative to gunpowder?
Edit: I want to clarify that i would be very glad if said weaker alternative had around the same power of an airgun, like the Girardoni rifle.
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Gunpowder is a spectrum; that is, there are many *many* variations on gunpowder.
Zinc-sulfur would be one alternative, though I doubt it would be "weaker" than gunpowder -- have you ever seen video of an actual zinc-sulfur rocket, compared to a black powder engine (like Estes model rocket motors)? Zinc-sulfur is actually closer to flash powder (metal as the fuel, mixed with an oxidizer -- in this case, sulfur -- but not intimately incorporated like good gunpowder), and any form of flash powder is very, very hazardous to use in a metallic confinement like a gun barrel -- confinement can cause pressures to spike far beyond even smokeless powder's normal operating ranges.
However, gunpowder itself ranges from "pretty bad, hard to ignite, slow burning" for primitive forms (just mixed powders) to "top notch" for commercially produced (and some homemade) versions, easy to ignite, fast enough to make good firecrackers -- even with the *same formula*. Add in variations of formula (extra sulfur to produce more smoke also make the powder slower and weaker, for instance) and there's a broad range of "gunpowder". If the makers are new to the trade, they may not yet have arrived at an optimum mixture, or (due to things like quality of the available charcoal, perhaps not completely in their control) even the optimum mixture they can make is not the best that could be made with the best ingredients -- just as 14th century gunpowder couldn't hold a candle to 18th and 19th century products.
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Ever played with an airsoft gun? They usually work with either regular air compressed from a pump or bottled CO2. Airsoft guns are way weaker than regular guns, with less muzzle velocity and usually shooting ammo with much less penetration power.
Alternatively you can use paintball guns. They don't kill, but [at close range the shots hurt like a son of a female dog](https://www.youtube.com/watch?v=GQtqdks_pYA&t=74) (which is why I eventually switched to laser tag). Switch the paint balls for polished hematite crystals (a form of iron) for a lot of fun and nonlethal hurt.
If you really wish to have a weak shootout, use slings instead of guns. You will have the least lethal skirmish ever.
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Can a super-Earth of approximately 1.5 Earth-radius and 3.0 Earth-mass be habitable? By habitable, I mean terrestrial with liquid water on its surface, a rocky ocean floor, and no thick hydrogen/helium envelope like that of a sub-Neptune. I keep getting mixed results from my research. I have seen suggestions that 2.0 Earth-mass may be the upper limit for ideal habitability and that more than that would have a thick primordial H/He atmosphere. On the other hand, I've found some suggestions that mass could reach up to 5.0 Earth-mass and still be terrestrial. I simply want to know if a 1.5 Earth-radius, 3.0 Earth-mass planet could possibly sustain the above listed habitability conditions.
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My calculations for the properties of your super Earth type planet are:
* Average density of 4.902 g/cm$^\sf{3}$, compared to 5.514 g/cm$^\sf{3}$ for
Earth
* Gravity of 13.094 m/s$^\sf2$, compared to 9.78 m/s$^\sf2$ for Earth
* Escape velocity of 15.82 km/s, compared to 11.184 km/s for Earth
The average density of the planet if fine. The surface gravity is 33.3% higher than Earth's, which is an issue in that in increases the escape velocity, which affects the gases retained in the atmosphere. It will also affect how life forms might develop to overcome a much higher surface gravity.
This might result in the muscles of animals being stronger than on Earth and flying animals might be lighter, or have stronger muscles.
As L. Dutch states in the escape velocity will have repercussions regarding atmospheric gases and possibly the required temperature to avoid hydrogen and helium retention.
Even a temperature of 350 K is 77 $^\circ$C.
Increasing the diameter of the planet to 1.75 Earth radius and keeping the mass as 3 Earth masses would reduce the surface gravity to 9.6 m/s$^\sf2$ (98% of Earth's) and the escape velocity would be 14.64 km/s. The average density would be 3.089 g/cm$^\sf{3}$, which would be similar to the Jovian moon Europa.
Keeping the diameter to 1.5 earth radii and reducing the mass to 2.5 Earth masses would change the density to 4.085 g/cm$^\sf{3}$, the surface gravity to 10.912 m/s$^\sf2$ and the escape velocity to 14.44 km/s. This would be a better scenario.
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According to [this calculator](https://www.omnicalculator.com/physics/escape-velocity), with your parameters your planet will have an escape velocity of about 16 km/s.
[According to this graph](https://en.wikipedia.org/wiki/Atmosphere#Structure) correlating the escape velocity and the temperature of a planet to the gases it can trap,
[](https://i.stack.imgur.com/7TlTP.png)
to not trap hydrogen and helium the planet would need to be at somewhere around 350 to 400 K.
With those temperatures it's far from being habitable according to our definition. It might still host some sort of extremophile life form. Having liquid water on the surface with those temperatures would require higher atmospheric pressures, somewhere above 10 bar.
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Short answer:
Any writer can depict a habitable planet with any mass, radius, density, surface gravity, or escape velocity that they want to, without worrying about being arrested by the science fiction police. But a writer who cares about scientific plausibility in their stories should note that some scientists calculated that the maximum mass limit for a habitable world should be about twice the mass of Earth. A writer who cares about their scientific plausibility should research those calculations.
Long Answer:
There is a big difference between a planet habitable for life forms that are carbon based and use liquid water and can survive in conditions that some Earth life forms can survive in, and a planet where humans and beings with similar environmental needs can survive.
Part One of Two: A Planet Habitable for Humans.
I note that native intelligent beings or large land animals would probably need an atmosphere rich in oxygen, like that of Earth. And also any Earth humans who visit the planet would need an oxygen rich atmosphere if they walk around without breathing apparatus, and would need a small enough surface gravity that it wouldn't endanger their health, unless they can use some sort of antigravity devices which can protect them from dengerously high surface gravity.
I'm sure that a number of science fiction stories have settings where no human beings were in contact with any of the characters in the story, and where humans are never mentioned. Several such stories are listed in answers to this question:
[https://scifi.stackexchange.com/questions/94253/what-is-the-first-work-of-science-fiction-in-which-no-character-is-an-earthling/94337#94337[1]](https://scifi.stackexchange.com/questions/94253/what-is-the-first-work-of-science-fiction-in-which-no-character-is-an-earthling/94337#94337%5B1%5D)
The small number of early stories mentioned may indicate that such stories are very rare. Since the question was about the first such story, possibly that sub genre has become a lot more common in the decades since the latest one mentioned in an answer.
As far as I know, the first and only scientific discusssion of the planetary attributes, including mass, radius, density, surface gravity, and escape velocity, for a planet to be habitable for humans is *Habitable Planets for Man*, Stephen H. Dole, 1964, 2007.
Here is a link to a pdf of the 1964 edition:
[https://www.rand.org/content/dam/rand/pubs/commercial\_books/2007/RAND\_CB179-1.pdf[2]](https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf%5B2%5D)
Later research may have made some of Dole's calculations obsolete.
In the chapter "Introduction to General Planetology" Dole discusses the relationship between a terrrestrial planet's mass and its other characteristics.
In figure 7 on page 28 Dole graphs the mass/volume relationship between the masses and volumes of stars and planets. In figure 8 on page 30 Dole graphs the density-radius relationshp for the then known terrestrial planets.
Note that Dole's figures give strightforward relationships between the mass, density,and radius of terrestrial planets. However, more acurate measurements since then of the data of various solar system bodies and exoplanets may have modified that.
For example, Mercury is much denser that such a small planet should be. It is now speculated that Mercury was much larger and had a lower average density until it collided with a smaller planet billions of years ago, and all of the lighter material was ejected from Mercury, leaving it excessively dense.
And many of the large moons in the other solar system are known to have low densities because they are mixtures of rock and ices of water, ammonia, and other substances which are liquid at Earthly temperatures. It is also now believed that worlds can migrate from where they form outward from their star or inward toward their star.
So it is possible that a partially icy world with a lower density than a totally rocky terrestrial planet could migrate inward toward its star and enter the circumstellar habitable zone of the star, and thus have temperatures suitable for life.
But of course there are limits to how low the density of such a world could be without being totally covered by an ocean many miles deep.
Part two: A Habitable World for Life in General.
And if a writer is certain that no humans or oxygen breathing land animals will ever need to survive unprotected on his planet, for all of their lives or for short visits, he can make it habitable for some life forms but not for humans or for oxygen breathing land animals.
Most scientific discussions of the habitablity of exoplanets in other solar systems discuss habitablity for carbon based, liquid water lifeforms in general, and not the more specific case of humans in particular. Thus a planet can be considered habitable for life even if an unprotected human would die within seconds or minutes anywhere on that planet - after all, many lifeforms on Earth flourish in parts of the biosphere where unprotected humans would died in minutes or seconds.
So what are the limitations of mass for a planet habitable for life in general, and not specifically habitable for humans?
"Exomoon Habitabilty Constrained by Illumination and Tidal Heating", Rene Heller and Roy Barnes, *Astrobiology*, Volume 13,number 1, 2013, is a comparatively recent discussion of the possibile habitability of worlds in other solar systems, in this case as yet undiscovered exommons obiting exoplanets in other solar systems. Heller and Barnes do not mention any reason to suppose that exomoons could be habitable if they were outside the mass range for an exoplanet to be habitable. Therefore they summarize scientific opinons about the mass range for potentially habitable worlds.
[https://faculty.washington.edu/rkb9/publications/hb13.pdf[3]](https://faculty.washington.edu/rkb9/publications/hb13.pdf%5B3%5D)
In section 2. Habitability of Exomoons, the last paragraph before section 2.1 *2.1. Formation of Massive Eexomoons*, on page 20, discusses the mass range for habitable worlds, including exoplanets and exomoons.
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> An upper mass limit is given by the fact that increasing mass leads to high pressures in the planet’s interior, which will increase the mantle viscosity and depress heat transfer throughout the mantle as well as in the core. Above a critical mass, the dynamo is strongly suppressed and becomes too weak to generate a magnetic field or sustain plate tectonics. This maximum mass can be placed around 2M4 (Gaidos et al., 2010; Noack and Breuer, 2011; Stamenkovic´ et al., 2011).
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Their source for the importance of plate tectonics for habitability is:
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> Williams D.M. Kasting J.F. Wade R.A. Habitable moons around extrasolar giant planets. Nature. 1997;385:234–236. [PubMed] [Google Scholar]
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Their sources for that maximium mass limit of 2 times the mass of Earth are:
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> Gaidos, E., Conrad, C.P., Manga, M., and Hernlund, J. (2010)
> Thermodynamics limits on magnetodynamos in rocky exoplanets. Astrophys J 718:596–609.
>
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>
>
> Noack, L. and Breuer, D. (2011) Plate tectonics on Earth-like
> planets [EPSC-DPS2011-890]. In EPSC-DPS Joint Meeting 2011,
> European Planetary Science Congress and Division for Planetary Sciences of the American Astronomical Society. Available
> online at <http://meetings.copernicus.org/epsc-dps2011>.
>
>
>
>
> Stamenkovic´, V., Breuer, D., and Spohn, T. (2011) Thermal and
> transport properties of mantle rock at high pressure: applications to super-Earths. Icarus 216:572–596.
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>
So a writer who is careful to design only worlds which are possible according to current science should research the importance of magnetic fields and plate tectonics to the habitability of worlds, and also research whether those calculations that the maximum possible mass of a habitable world is only twice the mass of Earth are correct.
Added 07-23-2022
The question asked about a world with 1.5 Earth radis and 3.0 Earth radius. Other answers may have done the calculaitons, but such aworld would have 1.5 cubedthe volume of Earth or 3.375 the volume of Earth, with 3.0 times the mass of Earth.
Thus it would have a lesser average density than Earth, about 0.8888888 times that of Earth. That would be an average density of 4.9013328 grams per cubic centimeter.
So you might assume that the varius materials which your planet was made of would have an average density 0.8888888 that of Earth. And a writer might worry about whether there will be enough highly dense elements and compounds on the planet for the needs (whatever they may be) of his story.
It gets worse. All planets are much denser in their cores, where their matter is being crushed and compressed to higher density by the matter above it. Teh more massive the planet, the more the core matter will be compressed to higher density. With three times the mass of Earth, the weight of even more thousands of kilometers of rock above will compress the core material even more. Thus the materials would need to have, when under zero pressure, an average density much less than 0.8888888 that of Earth, to have an average density of 0.8888888 when being compressed inside a planet with 3 times the mass of Earth.
Fortunately some heavy elements form cmpounds with much ligher elements, and some of those compounds are light enough to be found in Earth's crust. So the planet's crust should have some heavy elmeents in various compounds and ores, though a smaller percentage than on Earth I guess.
With an average density of 4.9013328 grams per cubic centimeter, the planet would be less dense than Mercury, 5.427 grams per cubic centimeter, or Venus, 5.243 grams per cubic centimter, but more dense than Mars, 3.9335 grams per cubic centimeter, or the Moon, 3.334 grams per cubic centimeter. And the good news is that all four astronomical objects are not covered with hundreds of miles deep world wide oceans, but have exposed solid surfaces. So a world doesn't need to be largely liquid to have such an average density.
According to these calculators:
<https://philip-p-ide.uk/doku.php/blog/articles/software/surface_gravity_calc>
<https://www.calctool.org/astrophysics/escape-velocity>
Such a world would have a surface gravity of 1.34 *g* and an escape velocity of 15.82 kilometers per second, 1.414 times that of Earth.
A comment by Xi-K says:
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> Looking back at my calculation, my original was exactly 3.128 times Earth-mass with a radius of 1.464 Earth-radii.
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Using those figures, the planet would have 3.128 times Earth's mass in 3.1377853 times Earth's volume, and thus a density 0.9968814that of Earth, or 5.496804 grams per cupic centimeter, a very small difference. It would have a surface gravity of 1.46 *g*, and an escape velocity of 16.35 kilometers per second.
I don'tknow if any human characters are desired to visit or colonize that planet. Dole, in *Habitable Planets for Man*, decided that humans wouldn't want to colonize a planet with a surface gravity higher than 1.25 o r1.5 *g*, and the world as imagined would have surface gravities in that range and should be rather uncomfortable and unhealthy for long range human habitation.
Escape velocities of 15.82 or 16.35 kilometers per second might be high enough for the world to retain dense atmospheres of hydrogen and helium and become some sort of mini Neptune.
Fortunately helium would probably be safe to breath at a considrable atmospheric pressure, though it would be hard to have large amounts of hydrogen and oxygen in an atmsopehre without it burning into water.
So possibly your planet accumulated a large, dense, unbreathable, atmosphere of hydrogen and helium and then migrated to the habitable zone of your star. It's escape velocity was still high enough to retain hydrogen and helium, but it might be unable to capture more of those gases, since they might not be found that close to the star anymore. And then it lost most of its atmosphere, retaining only heavier gases like nitrogen, oxygen, carbon dioxide, and water vapor, plus trace gases.
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> The impact of a large meteoroid can lead to the loss of atmosphere. If a collision is sufficiently energetic, it is possible for ejecta, including atmospheric molecules, to reach escape velocity.[9]
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> In order to have a significant effect on atmospheric escape, the radius of the impacting body must be larger than the scale height. The projectile can impart momentum, and thereby facilitate escape of the atmosphere, in three main ways: (a) the meteoroid heats and accelerates the gas it encounters as it travels through the atmosphere, (b) solid ejecta from the impact crater heat atmospheric particles through drag as they are ejected, and (c) the impact creates vapor which expands away from the surface. In the first case, the heated gas can escape in a manner similar to hydrodynamic escape, albeit on a more localized scale. Most of the escape from impact erosion occurs due to the third case.[9] The maximum atmosphere that can be ejected is above a plane tangent to the impact site.
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<https://en.wikipedia.org/wiki/Atmospheric_escape#Impact_erosion>
So possibly your planet suffered a few impacts after migrating to the habitable zone, and those impacts removed the hydrogena and helium from its atmosphere, while perhaps adding some heavier gases like nitrogen, oxygen, water vapor, and carbon dioxide.
Cometary impacts are one possible reason why Titan has an atmospherer billions of times as dense as those of the similar moons Ganymede and callisto.
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> An alternative explanation is that cometary impacts release more energy on Callisto and Ganymede than they do at Titan due to the higher gravitational field of Jupiter. That could erode the atmospheres of Callisto and Ganymede, whereas the cometary material would actually build Titan's atmosphere.
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<https://en.wikipedia.org/wiki/Atmosphere_of_Titan#Atmospheric_evolution>
The number of major impacts by comets, asteroids, and possibly by other planets, your world would suffer, and the impact that each would have had on its atmosphere, adding and/or subtracting gases, is something that would not be obvious from even the most detailed description of the present state of your ficitonal star system. So if you need to explain why your world has the atmospheric composition desired for the story instead of a dense atmosphere of hydrogen and helium, large impacts in the past would be a reasonable explaination.
[Answer]
**Blast those pesky little molecules off with the solar wind.**
[](https://i.stack.imgur.com/AXAfg.jpg)
<https://svs.gsfc.nasa.gov/4370>
The graphs consider mass and temperature and that is that. But these planets do not exist in a vacuum! Ok, they do, but nearby your planet is its star, and the solar wind can strip away gas molecules too. A planet which lacks a protective magnetic field will lose atmosphere to the solar wind as is thought to have happened with Mars.
Your big planet can have a weak or weakening magnetosphere such that it has lost lighter molecules to the wind. You are not constrained by gas laws here - you can assert that your star is strong enough to do what you need and your planets magnetosphere not strong enough to save the hydrogen and helium.
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I was wondering why Venus, with minimal magnetosphere, still has an atmosphere much thicker than that of Earth. The answer is that Earth had that thick atmosphere too, but did something different with it.
<https://space.stackexchange.com/questions/13833/how-does-venus-thick-atmosphere-survive-against-the-solar-wind>
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OK, this post will need something more if it is going to garner any upvotes. Let us add something else to deal with the hydrogen, which is 90% of the hydrogen / helium envelope. Let us biology away that hydrogen! Venus has a boatload of CO2 and Earth once did as well, but now a lot of that C is locked up in carbonate rocks and biology, and the O is loose as O2 or locked in water.
So too your super earth. Life forms take CO2 and hydrogen and make sugars or other reduced carbon forms. Oxygen is released and it also gets cozy with hydrogen, making water.
That will leave a fair bit of helium in the atmosphere. I think that will be ok.
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[Question]
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Yep, it's another Nymph-related question!
**Recap:**
Nymphs are "born" when large amounts of residual life force (say, in a town cemetery or slaughterhouse) build up and combine with the magic bleeding into this world from an alternate reality. They are beings of nature, manifested as human women in their prime, and their clothing is akin to that of Tinker Bell and her friends.
Now, Nymphs are just about immune to hot and cold; they can wade through lava flows and stroll through the Arctic. They can also breathe air and water with equal ease, cannot be poisoned or burned and survive the pressures on the seafloor (meaning the continental shelf and abyssal plain, *not* the intense pressures inside the trenches, AKA canyons of the sea). They also know any plant or animal in their environment and can speak and understand any human language.
They sound like they'd make *great* warriors, right? Especially considering they have superhuman strength, speed, endurance, healing factor, and all that (see Ton Day's answer to [Nymphs and Humans: Preventing Anarchy](https://worldbuilding.stackexchange.com/questions/195737/nymphs-and-humans-preventing-anarchy). for more on that). But no, that's not the case. Every Nymph is born naive, curious, peaceful, and with a deep love and awe of nature, along with an equally deep longing for purpose and belief in fate.
In fact, Nymphs are so passive that they are *obliging*; if they encounter a predator (say, a Titanoboa) they'll not only allow it to eat them, but they'll hop in its mouth and wriggle down its throat so it doesn't have to catch or even *swallow* them! Granted, in this case, these instincts are a population check on the biologically immortal Nymphs, and it's not even the end for them (please see [Finding Nymphs Before Predators](https://worldbuilding.stackexchange.com/questions/195608/finding-nymphs-before-predators?noredirect=1&lq=1) for more on that), but this does pose a problem to creating a society of warrior Nymphs.
Now, I believe it's *possible:* Nymphs are beings of nature, and nature has an aggressive side; they may be childlike, but there are child soldiers; however, there are a lot of rather significant barriers to accomplishing this. Basically, **I'm looking for a way that someone can collect Nymphs after they spawn and convince them to become warriors *despite* their peaceful, extremely passive, nature-loving personalities.**
My question is: **Can Training Alone Create a Society of Warrior Nymphs or Will Other Methods Be Necessary?**
*Some of my thoughts:*
1. Is this even feasible? Sure, people can overcome their instincts to a certain degree, but there are also plenty of instances where instinct overcame discipline. Can Nymphs, which for the purposes of this question are essentially human women with hard-wired traits and beliefs, change their natures like this? Or in other words, can people hard-wired to act or believe a certain way (through their *biology*, mind you) overcome and even change their nature?
2. Everyone has a certain line that if crossed will result in them resorting to violence, yes? However, even though Nymphs can and will fight to survive (metaphorically of course) once they've found a purpose, they love and respect nature, so hurting anything natural will probably be unthinkable to them. Then again, they *are* human, and humans can adapt to just about anything (mentally speaking)....
3. By "warrior Nymphs," I mean an Amazon-type society where the Nymphs live isolated from the rest of humanity. Their targets are animals *or* humans, whatever attacks them. They're not going *after* people or creatures, just fighting to protect themselves from the creatures that want to eat them. FYI, an IRL example of this would be Switzerland's policy of armed neutrality.
As always, I appreciate your input and feedback, thank for your help! If you choose to VTC or downvote, please give me an explanation so I can improve this question and post better ones in the future.
[Answer]
**Nature isn't peaceful**
I don't think you need to go too far in your justification, it's not like nature is a quiet and peaceful place. I would argue that it wouldn't be impossible for an older nymph to arrive at the conclusion you want by themselves, but if you want to be active in the process or have some event accelerating that process, maybe just showing them some beasts mauling each other might eventually make them realize that nature isn't just about grassy hills and tweeting birds. if you want to sprinkle in some hate toward humans you probably won't have to go further than a logging operation and soon enough they might just take arms.
[Answer]
Training is not what makes a whole society. Well, at least not alone. **In order to start a group of people working together, you need to have common goals planted in a good geographic and political soil, then the birth of its associated culture should be able to sustain it.**
Your question is not ultimately clear on whether you want someone who is not intimately part of the "nymph-azon" to play an important role or not, but it's more likely a nymph or a very pro-nymph person begin this, because an isolationnist, neutral warrior society which isn't yours isn't very useful, unless you use them a territorial barrier between you and your foes. But in this case it's probably wiser to make them join your alliance rather than act as a simple wall.
So down it goes to nymphs and pro-nymphs people, working together to make a military strong, isolationnist society. I'll go through the process I'd use to make such things :
## The Goals, the desire and the hatred
Start with some common, deep goals. Your goals can be many, and can draw its existence from an overall feelings your nymph will have. Here is a set of three emotions, which should be enough to start an isolationnist, military society :
* They form a natural bond with the place they are born with, like a mother to a child : It's an almost essential trait if you wish to keep them from moving around because of their innate curiosity.
* They are still confused and pondering what their purpose in the threads of fate are, so they wait and meditate until they understand it : Pushing this further, they might decide that their fate is helping other nymphs find their own destiny, so they would take a much longer time before saying goodbye to this world.
* Finally, they have seen what other civilizations made on their environment, rooting out the nature of it, and they so much dislike it : It's classic, but oh bell how negative emotions are good at creating military wishes.
As you can see, I've taken the average nature of the nymphs and took out these to prevent them from moving too much, die too early to form anything constructive, and have a good reason to develop weaponry and strategies. Now, with enough of these, you can make a society whose goals is to protect their place of birth and meditation from any intruders.
*A tiny note : Depending on the density of nymphs/km², not all nymphs need to have these emotions. If you have enough nymphs, but only half of them share these feelings, half of these will find another place (or a belly) to fulfill their wishes, but it's fine, they were never really part of your society in the first place!*
## Ideal geographic and political soils
Your best bet to grow such society is to have an island away from people (I assume nymphs prefer lands over seas). Because it's harder and riskier to make trade flows through the sea, less people will come into contact with nymphs, and therefore less nymphs will be attracted away from their village. Also, young, tiny societies are very vulnerable, so you need some initial time to make them grow into something more resilient. In other words, don't put them inside an existing kingdom, they won't last.
Also, note that not all goals need to be achieved at the same time, only having the first two ones are necessary to make a stable society. The third one will come from the time an invader will come, forcing out the nymph "villagers" of their peacefulness.
In general, if you wish to have strong military intents is to either make the world very dangerous, or make two neighboring societies different enough so that cultural tensions grow. So keep it in mind if you wish to make nymph-azons.
## Potential culture outcome
It's going a little further than your original question, but it may be interesting to see what can come out of this.
When you have common goals, and a good soil to grow, you can have many potential culture to make it last a lot longer than the few individuals who started it. Take those goals, the way you need to live there and translate them into traditions your nymphs will have. These traditions can then be given to any new born nymph as a way of life they can follow, continuing the society.
For instance, because nymphs are born from the death. in order to ensure a good number of nymphs wandering around, you can tell that these nymphs in particular find the need to accelerate the cycle of life and death (while keeping the nature's balance) in order to find their purpose through the many mortal beings they watch live and die, to study what the end means. Or, because of their hatred towards human, they are a group of self renewing refugees going out as outcasts of human societies and back to their roots, sharing a partially multicultural traditions due to the knowledge they acquired during their travels. It's two of many, many traditions you can imagine, and that would match your base intentions.
## Ending point
Note that this is an overall process, and may not contain exactly what you want, or the composition you wish. But it's like a salad, you can put whatever feels nice into it and try to obtain a similar flavor! If you have other believable and relatable feeling-induced goals, other potential geographic and political conditions, and a long lasting culture sprouting from all of these, then you are a winner!
[Answer]
## Feelings
The only way I can imagine a peaceful entity to become agressive or resort to some type of defensive state are feelings.
Let's say a Nymph gets in love with another Nymph, they were born at the same area, some peaceful forest. They lived together for years, developing a strong bond. When suddenly humans ( or other predator ) comes over and kills and consumes one of the Nymphs with strong bonds, therefore losing the loved one and then a new feeling comes over to the Nymph who lost the loved one, such as: **pain, anger, sadness**.
After becoming overwhelmed by these feelings, the Nymph now wants **revenge** upon those who took it's loved one.
## But how do they become a society of warrior nymphs?
The lonely Nymph now wanders into the forest trying to find the best way to get it's revenge. Then new Nymphs start to rise and the lonely Nymph convince the newborn ones that Humans ( or other predators ) are evil and will kill any Nymph at sight, so to avoid those bad feelings and sorrow, the Nymph which was lonely started training and training others to make some kind of *Nymph resistance*, arming themselves with stones, primitive spears or anything they could to **at least** defend themselves against predators.
After a while surviving predators and growing in numbers, the Nymphs now start to move closer and closer to a ***Nymph warrior society*** which relies on the feelings and bonds between the Nymphs, mainly love for each other.
[Answer]
**Mind control chips**. People (sensu lato) have been trying to do this [for a long time](https://www.thesun.co.uk/news/7949997/ia-remote-controlled-dogs-brain-electrodes-project-mkultra/). Obviously the technology has advanced a long way since that time. Nymphs heal well, so the usual practical health issues with large-scale brain manipulation are reduced.
Overall, mind control tends to focus on stimulating the [nucleus accumbens](https://en.wikipedia.org/wiki/Nucleus_accumbens). This is sometimes called "pleasure" or "reward", but the true sense is *positive reinforcement*. A tobacco smoker may not truly enjoy his poisoned herb, but it *reinforces* behavior. Note that the nicotine does not *come with* a label that says it came from tobacco that came from a cigarette - the brain has to somehow pick out that the action of smoking has something to do with the positive reinforcement received. Before the herb was malappropriated by European tourists, native peoples used it more often to positively reinforce a ceremony of making peace.
With that in mind, an electrode or hidden reservoir of short-acting drug could be used to change nymph behavior, whether by getting them to follow simple commands or (more likely) by getting them to espouse particular philosophies. An obvious unholy grail of many a fell knight would be the [reading of words](https://www.kurzweilai.net/mind-reading-technology-identifies-complex-thoughts-using-machine-learning-and-fmri) from the human brain (There are more reputable sources, but those are some nice images). If you can positively reinforce thoughts *and* read the thoughts directly ... well, then you have something.
It has been 20 years since we have had any real notion of where the new "forever detainees" go, so I imagine that there is quite a body of research you could use to make this scenario more plausible -- if only you could read it.
[Answer]
1. You can have contrary desires: Humans Have an instinct that encourages them to avoid danger. They also have a need Of the respect of others this can go against Their desire to avoid danger in certain circumstance . The nymphs may have a bult in desire To give of themselves to nature but also a Built-in desire to survive And one may override the other certain circumstances. Your amazonians are just nymphs In a circumstance where Survival instinct overrides other instincts.
2. Magical mutation : You're amazonians are There result of whatever magic that created them going wrong Resulting in the kind of mutated nymphs, They're very similar to the others but slightly more aggressive more prone to violence and more concerned with survival.
Ideology: Perhaps the nymphs become convinced that their enemies are not part of nature or maybe even opposed to it.
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[Question]
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On Earth, at least in the United States, most marine science vessels are decommissioned Navy vessels. After all, it is far cheaper to reuse an old ship than to build a new one. The high weight capacity and large space on
Navy ships allow scientists to create amazing machines capable of lifting multi-ton submarines. However, it also offers no incentive for small, lightweight designs. In other words, a big ship creates big machines, a small ship would create small machines.
**So, on a world with little military influence, would the scientific machines be smaller and lighter?**
Edit: This question is asking about the plausibility of technology development, so I think this fits for Worldbuilding, correct me if I'm wrong though
[Answer]
# Depends what the country prioritizes
Contemporary research ships come in all sizes. According to [Wikipedia](https://en.wikipedia.org/wiki/Liberty_ship#After_the_war), many Liberty ships were converted for non-military duties after WWII, and Liberty ships were fairly big and clunky. However, those were cargo ships (as pointed out in comments) and I can't find large-scale examples of combat ships being converted to civilian research use. [The Office of Naval Research](https://www.onr.navy.mil/en/About-ONR/History/tales-of-discovery/oceanographic-research-vessels) shows plans for custom research ships in the post-war period. I see many examples of modern purpose-built research vessels. For example, the [CCGS Frederick G. Creed](https://en.wikipedia.org/wiki/CCGS_Frederick_G._Creed) is the kind of small and sleek ship you describe.
[](https://i.stack.imgur.com/qtgYn.jpg)
The real answer comes down to how much a given nation prioritizes scientific discovery. If science is a top priority, the country will put its energies into building the best research vessels for the given task. If a country relegates science to second-class status behind its military, then scientists will have to accept whatever is left over from the military.
In the real world, the armed forces and scientists have a complex relationship that's hard to describe in a short answer.
(EDIT: Clarified that Liberty ships were cargo vessels and extended conclusion.)
[Answer]
Depends on the mission.
* German oceanographic research ship [Sonne](https://en.wikipedia.org/wiki/RV_Sonne_(2014)), built for and owned by the federal department of education and science. Pretty big, long range, non-military.
* Turkish oceanographic/geophysical research ship [Oruc Reis](https://en.wikipedia.org/wiki/RV_MTA_Oru%C3%A7_Reis), built for and owned by the ministry of energy and natural resources. Pretty big, long-range, non-military.
* Danish fisheries research ship [Dana](https://en.wikipedia.org/wiki/Dana_(1980)), now operated by the technical university. Mid-sized, long-range, non-military.
* German research yacht [Eugen Seibold](https://en.wikipedia.org/wiki/Research_sail_yacht_S/Y_Eugen_Seibold), owned by a foundation and working for a Max Planck institute. Based on a motorized sailing yacht so they could shut the motor down and sail, to avoid contaminating samples. Also non-military.
[Answer]
Going from another angle: Mighty militaries means a mighty need of those militaries. And despite the horrors of war it is a major driving factor in scientific progression.
WWII (and by extention WWI) have produced much of our modern technology or improved it to consumer useability. Radio's, combustion engine's, rubber synthesis and even the fact that commercial airliners exist started because after the war there were many factories with the layout and technical know-how to build aircraft but no government to sell them to, so they started repurposing their airframes for commercial shipping and person transport.
When it comes to naval strategy it's about build strategy: How many and what type of boats can you make and where is the likely combat going to take place? So being able to build faster, lighter ships while still retaining armor is a necessity. If your military hasn't had a need to do that then I would suspect that the boat technology these scientists are relying on is going to be limited as well. After all if there's no billion-dollar business working on improving boats then the scientists are going to need to find the funding for it themselves.
[Answer]
The design (or selection) of a research ship is dictated largely by it's expected mission: where it is to operate. When you see research institutes operating a larger ex military ship, it means that they have more gear to carry, and will be operating that ship in all weather conditions. In a storm on the ocean, smaller is definitely not better. Smaller can get you killed in a storm.
Larger, on the other hand, costs a lot more to operate, and a ship's operating expenses can exceed it's purchase price within a few years. So if a research institute was researching coral growth, they'd get a smaller shallow hull coastal vessel that doesn't cost nearly as much to operate. And those are often ex military - yard patrol boats.
The design of the equipment is dictated by the mission, not the size of the ship. A deep water remotely piloted vehicle will be designed to operate for a given length of time, while withstanding the pressures that exist at the depths it will operate. Size really isn't a factor in that design... capability is.
A notable research ship, the [RV Petrel](https://rvpetrel.com/) is not ex-military, but is of a heavy weather open ocean design, with a huge bow to cut through large waves, a high bridge for better visibility during storms, and a deep hull to better withstand large waves that might capsize a shallow hull ship. This gives it the capability to safely operate in most any weather condition encountered. The same design is used on non military open ocean fishing vessels, open ocean tugs, and oil platform service ships, all of which need to operate in stormy conditions.
To get back to your original hypothesis: Research institutes in a nation with no active military would probably have ships similar to what is had today. They'd just spend more money acquiring those ships, as typically military ships are given to research institutes free of charge.
It may well be that in the absence of a huge military budget, research firms would get the funding to purpose build their ships. But, those ships would not necessarily be smaller and lighter than ex-military ships used today... they would be built to withstand the conditions the ship is expected to operate. Stormy weather - larger ship. Polar research - armored hull.
Or, maybe that peaceful nation would just purchase ex-military auxiliary vessels from another nation that has a navy, and some surplus ones for sale.
Finally, a surprisingly high number of ocean research projects are funded by a nation's navy, funding that would have to come from elsewhere in the absence of a navy. Military expenditures don't necessarily originate innovation, but they will accelerate it, if that invention helps them perform their mission better.
One example: When Bob Ballard went looking for the Titanic in the 1980's, he was actually contracted by the US Navy to survey the USS Thresher submarine wreck, which is also in the north Atlantic. The US Navy would prefer to keep the actual location of the Thresher wreck secret, as it does contain a (shut down) submarine nuclear reactor that an opponent might want to recover and study. Also, it's a military grave site - the crew remains are still with the wreck.
As a cover story for leaving port with underwater search gear, Ballard said he was looking for the Titanic, and to maintain that cover to foreign intelligence agencies that might be following his journey, they actually did have to go to the Titanic's estimated location and give a try. They were originally going to be on site for maybe a week before making a pass over the Thresher site, whose precise coordinates were known to the US Navy.
And, surprise - they just happened to lower their survey gear almost on top of the Titanic. Given the large search area, that was the providential needle in a haystack.
So a nation without a navy to protect it, might not fund ocean research as much.
] |
[Question]
[
In space somewhen in the future there's need to build a space station able to sustain heavy railgun fire.
How would you design it?
I was thinking about building something similar to a 17th century star fort but in 3 dimensions, but after making a model on SketchUp I'm beginning to doubt its viability.
Is there anything that could be done?
Supose you are dealing with almost infinite funds, you have a foundry in space, unlimited materials, unlimited energy (just to build the station), etc, don't worry about logistics for now.
It would be great for it not exceding the dimensions of an imaginary cube with an arista 2 km long.
This is my 4(\*2) points star fort from SketchUp:[](https://i.stack.imgur.com/bJ8rA.png)
I have developed the design a bit more, 8+6 cubic star:[](https://i.stack.imgur.com/jUUSh.png)
[Answer]
## Ricochets don't happen with railgun charges
Railgun projectiles viable for space combat will have very high velocities, at least ten kilometers per second. At these speeds, projectile delivers more kinetic energy than it's own mass in TnT. So it doesn't deflect, it vaporises upon contact like micrometeorites do, and the resulting plasma and shrapnel does the damage, which looks like this:
[](https://i.stack.imgur.com/WsHWu.jpg)
The far superior option would be to use a layered armor consisting out of thin sheets separated by empty space. The projectile hits the first layer, vaporises, and plasma and debree from the impact disperses in the empty space behind the first layer, oing greatly reduced damage to the secon layer, and so on.
[](https://i.stack.imgur.com/LbmsZ.jpg)
Bonus points in that whipple shield armor is very light compared to "proper" thick layers of armor.
And here is where you don't actually want to have too great angles between your craft surfaces and the enemy line of fire - because then the impacts will create larger gaps in your armor (Ejecta of the first layer will be directed sideways instead of straight down), reducing it's lifespan.
[Answer]
**1. Station is thick.**
Your station is stationary. That is how it got its name. Around the working part of your station you have strapped many large rocks of various types. You found these rocks in the neighborhood. Your station looks like a clump of rocks because for the outer kilometer, that is what it is. These rocks are not on a solid scaffold but frozen in place with icy sand. Incoming energy expends itself breaking the rock and melting the ice. Easy come easy go.
Thick Station is massive. Good thing it is stationary!
This would work against low power projectiles fired at close range. Those of you unfamiliar with the scifi show The Expanse: they do a great job depicting railguns like this.
---
**2. Station sees them coming.**
Relativistic velocity railgun projectiles still could mess up Thick Station. These would be fired from a specialty platform at some distance. They might be very fast, but light is faster. Acitve and passive sensors using the whole spectrum of EMR will easily see a fast moving incoming projectile. From a defensive standpoint a railgun projectile in space is nice as it cannot maneuver and once detected its course can be known.
Thick Station fires at the projectile, like an AEGIS system. Projectiles intercept the incoming railgun projectile at distance. The station's defensive projectiles are not moving fast because they do not need to. If the railgun hits one, both are converted to plasma and the plasma molecules rain harmlessly on the thickness of Thick Station. The automated defenses on Thick are good shots but usually send out a few projectiles to be sure. This works against space debris just as well.
[Answer]
Star Fort still seems to have too many flat surfaces. Make it spherical. That will offer sloped surfaces in all directions. Then - put multiple layers of armor on it. External layers could be made from thin sheets of metal (the term is I think Whipple shield), empty spaces between layers could be left empty or could be filled with aerogel to reduce spalling and shockwave expansion. Only deeper layers would be made from hard, dense metal. The idea is that fast moving projectiles will vaporize on contact with Whipple shields, energy will be dispersed before it reaches main armor. Sections of lighter armor are easier to replace after bombardment.
Because this is station, which doesn't have to move you could use as much mass as you want. For example for additional protection you could put water ice right below main armor as radiation protection and emergency heat sinks.
And put a lot active defenses between the fort and its enemies because even the best armor wont do much good against sustained railgun attack.
] |
[Question]
[
In my fantasy world, the manual repeating rifle (revolver action, falling block action, lever action, pump action, bolt action) is already a common weapon within human society.
If possible, I don't want any semi-automatic gun to be developed. If it is not possible, I want it to be delayed.
At the same time, magic is also prevalent. The details about magic and its relationship with technology will be elaborated on another question.
With regards to my current question, I want to know what the consequences would be of the tech that capable of producing manual repeating rifles to society as a whole.
For example:
* Would there be automobiles?
* What would the state of the mining industry be?
etc.
The reason I want to have these details fleshed out is because I don't want a reader to say "well, if they have repeating rifles, why don't they have {obvious knock-on technology that would come about as a result}?"
[Answer]
*Very well, if you insist.*
While other people have provided rather complex analyses of industrial and pre-industrial era weaponry, and they're all very good, there is one concept that needs to be adressed. That thing is **cost efficiency**.
Repeating guns, even rifles aren't as modern thing as we might think. First repeaters have appeared as early as first half of 17th century, for example: <https://en.wikipedia.org/wiki/Kalthoff_repeater>
Here is an example of slightly later gun - explained: <https://www.youtube.com/watch?v=UyBPaXbp7Qg>
These guns were quite complex, but they had one massive drawback - they were expensive and it wasn't possible to produce them en masse. They were used - if at all, by elite units such as royal guards. To field them as main weapon wasn't really effective though - if you could pick between 20 people with matchlock muskets, or one with a repeater piece, 20 muzzle loaders are just better. Complex mechanism of a repeater is more prone to breaking as well, so you're going to pay much more for maintainance and repairs. Finally, these repeaters are usually somewhat harder to learn with - which wasn't problem if they were used by unit like the royal guard, but could pose problem if used in field by conscripts.
**That means, if society allows fielding of repeaters as main weapons, they've already brought manufacture costs down - which means advanced gunsmithing tools, and advanced methods of production.** With that you're looking at around 1870's earliest. What does this necessitates?
You can *probably* expect steam power being widespread. Advanced tools and experience with making gun barrels allows steam engines being invented and spread wide. Expect trains and steam powered ships - though with magic existing, steam powered ships might be experimental/luxury items rather than widespread, as long as your magic allows for magically enhanced sailing. Mining will certainly be assisted by steam engines pulling carts, unless your society practices slavery on large scale.
Another key thing is that production of iron needs to be quite advanced to bring down the costs of firearms. With great experience in iron making, you can expect some steel making processes like <https://en.wikipedia.org/wiki/Bessemer_process> being discovered, and thus steel will be more acessible than it was in early modern period. Having good steel tools is rather important to achieve cheaper guns. Next important factor is business model. Gunsmiths will have large workshops of small-factory-style, to be able to make repeater guns cheap enough. You can, therefore, expect other businesses to follow similar model of production.
**TL;DR: You can expect something similar to 2nd half of the 19th century industrial society.**
*Edit: However, it is worth mentioning that your fictional country doesn't need to have society mirroring the industrial society, as long as it is rich enough to buy guns and other tools from countries that do, and its rulers are enlightened enough to import these. If so, put some distance between those countries, to make sure the exporting countries don't feel existentially threatened by the country they're selling the weapons to.*
[Answer]
Modern firearms need a lot of technology to be made, even simple bolt actions, lever actions, and pump actions only became possible with the availability of **powered mills, drills, and lathes** - all these interlocking faces are made on this heavy machinery. let's look at the inside of a John Browning design of 1879:
[](https://i.stack.imgur.com/gE5bn.png)
That breach loading, falling block firearm heavily relies on parts that need a very precise fit. While the final fit will be made with files (*hand fitting*) the rough work is done on mills. But how far back do we need to go to get out of the need for industrial tooling? Well, let's look at the history of firearms in Japan how far you can get without modern tooling and machinery:
# Technological requirements for gun technology
As long as you don't want modern machinery tooling, you limit your firearms availability and design quite a lot to matchlocks and flintlocks, as these do not require low tolerance machining. The moment you allow somewhat crude machining and steam power (or a similar mechanical power source), the output of firearms increases massively as the barrel manufacturing gets much easier and parts can get preconfigured to an almost fit. Even with Flintlocks, the mere existence of good machining does result in advanced guns like the [1819 Hall Rifle](https://en.wikipedia.org/wiki/M1819_Hall_rifle) where the chamber tilts upwards, allowing much faster loading than having to ram a bullet down the whole barrel - especially in combination with the paper cartridge invented at the same time. Their downside? [They were more complex to produce](https://www.youtube.com/watch?v=vpW054cVfHc) as the parts had to be made all to one standard, it took Mr. Hall about 2 years to assemble the first rifle - because he produced only one set of parts, one after another, all to the same standard. Contemporary attempts at the same ould use jigs to hand-fit all other parts to achieve the same on a piece-by-piece basis. But they were also one o the first 'interchangeable parts' guns that would become the dominating type 100 years later.
To allow percussion caps, the next logical step on the way to fully self-contained cartridges, you will need advanced chemistry and somewhat precise machinery. The next step on the way to the fully self-contained cartridge demands developments in the stamping/pressing of brass to create the shells. The first ones will be rimfire, adding the primer into the bulge of the bottom, and only later centerfire.
The moment you allow precise machining with only [some hand-fitting afterwards needed](https://www.youtube.com/watch?v=xOHEZhKVyJ4), you also unlock most of the Browning designs. Note that John Browning singlehandedly dished out more than 120 patents on firearms and firearms parts, and in his lifetime guns went from percussion cap tilting breach blocks like the [1843 Side Lever Hall Carabine by Simeon North](https://www.youtube.com/watch?v=b53dlItu4r4) over his (above shown) early centerfire breach loading falling block, cartridge fed lever guns (his invention) and bolt actions beyond.
Hand-cranked revolving cannons like the [1872 Hotchkiss revolving gun](https://en.wikipedia.org/wiki/Hotchkiss_gun) use a similar mechanism to the 1861 mechanism invented for the [Gatling gun](https://en.wikipedia.org/wiki/Gatling_gun), automatically extracting and inserting shells. These guns are just a tiny step from fully-automated firing using some clockwork. But the main limiter for gun development to rapid-fire was not the mechanical problems. In the US, the ministry was concerned about the ammunition supply chain and thus did not adopt the Henry/Winchester.
Once machining gets even **more** precise, you are in the area of about 1850-1890s machining tech, but you also unlock guns with totally interchangeable parts. You get bolt actions, and once you have bolt actions, the step to semiauto guns is not that large: the Ross rifle experimented on [semiauto](https://www.youtube.com/watch?v=T2p85ImYjAA) and even [full auto](https://www.youtube.com/watch?v=1UI0XvrIfl0), using a bolt action core! The ability to the first fully automated machine guns happened for the most part in the late 1890s and into the world war years (such as the german [08/15](https://en.wikipedia.org/wiki/MG_08#MG_08/15), the 1915 revision on the 1908 machine gun), but small caliber self repeater development mostly happened in the interwar period. Adoption of semiautomatic and automatic weapons for the whole army only started in the second world war, when stamping technology had advanced so much to allow almost fully stamped construction and thus mass production.
## Volley Guns
A type of gun ignored above is the [Volley Gun](https://en.wikipedia.org/wiki/Volley_gun), where firing the gun does fire a number of barrels in rapid succession. These guns came up very early - reports from 1339 indicate the use of multi-barrel cannons that only needed to be triggered once, there had been [14-barrel flintlocks](https://www.youtube.com/watch?v=W5yZJugzGXM) and in the 1700s the [Nock Volley Gun](https://www.youtube.com/watch?v=SbDhwdjL0jo) was a typical armament on ships. These "rapid-fire" guns and the similar [mitralleuse](https://www.youtube.com/watch?v=W5yZJugzGXM) can't be stopped in their firing cycle, but ultimately are pretty much machine guns/cannons in their own right. Making them is often a thing of casting and, and does not need highly developed machining in the crudest forms but can become quite intricate in smaller calibers. Once the paper cartridge with percussion cap or self-contained cartridge is available, all-barrels-at-once firing is a rather simple task.
# The History of Firearms in Japan - an example case of frozen technology
Generally, we need to take in mind that Firearms had three distinct periods in their pre-Worldwar development in Japan: Their initial arrival to the battle of Sekigahara, the Edo period, and then the Meji period onwards.
Note that the guns in the first two eras were manufactured in handiwork without machining. Each one had parts made for this one gun; even if gunsmith workshops might produce repeated parts for one of their models in larger quantities (like the flat springs), there was a lot of individual fitting, making each one unique to some degree.
## Arrival and propagation
Firearms were not invented in Japan. First, some kind of grenades came with the Mongol invasions. Next came hand cannons and larger, and quite early wooden artillery from china in the 12 to 1400s by trade. The Japanese would adopt the [wooden cannons](https://en.wikipedia.org/wiki/Wooden_cannon) for sieges - pretty much a treetrunk drilled out and given a hole on the side to light the powder and some bands to secure the gun. Neither the hand cannons nor the wood cannon was easy to use, aim and the latter wore out fast, allowing at best about a dozen shots before the gun is useless. Hand cannons, cast in china, also were hard to manufacture, and as a result, neither of these found widespread adoption.
However, the matchlock type that arrived in Japan was already outdated when it came to there, most likely via Portuguese travelers or shipwrecked people 1543. It's hard to say which design it was - a Chinese copy of a Portuguese design or an Ottoman copy of a Portuguese design that was brought to china first. In any way, it wasn't the state of the art in Europe and about a decade behind the developmental curve there.
The first adoption in larger quantities came around 1549 - about 6 years after their arrival. That Year Oda Nobunaga ordered 500 firearms. An advisor of his reports, that just *boring the barrel by hand* for a gun would take about a month, so it hints heavily at the number of gunsmiths employed just to outfit those guns within a year or two. Note that this massive adoption does come from the relative ease of training: it takes about a week to train someone to be a decent gunner, but years to be a decent bowman or artillerist with wooden cannons and mortars. But training didn't stop then: The Oda tactic was to have the gunmen rigorously hold rank and fire in volleys, switching out the front line to reload after each volley. The tactics changed vastly.
[In 1563](https://books.google.de/books?id=YPkYMoO0ycIC&pg=PA147&redir_esc=y#v=onepage&q&f=false), some minor clans clashed and the resulting battle had 33 *confirmed* woundings with *teppo*, in a battle that had only 12 other woundings! So by this time, firearms had gotten their way into normal warfare. In 1570, 7 years later, Oda Nobunaga fielded 3000 firearms in the [Battle of Anegawa](https://en.wikipedia.org/wiki/Battle_of_Anegawa), making up 13% of his total army of 23000 (not counting allies on either count here). These could fire a volley of 1000 per minute continuously. These battles would mark the moment tactics changed dramatically, and the next big one was to cement the changes:
The [1575 battle of Nagashino](https://en.wikipedia.org/wiki/Battle_of_Nagashino) pitted the Oda and their Tokugawa allies against 12000 of the Takeda cavalry troops. Among the 38000 troops on the oda side, about 1 in 4 was armed with a Tanegashima. While the Takeda had previously won against armies outnumbering them 3 to 1 with their heavy cavalry tactics, the heavy reliance on rigorously trained gunmen that shot in volleys did break the Takeda clan's Warmachine. Cavalry, having become the Takeda trump card in open field battle just some decade or two ago, suddenly was obsoleted. Positioning, simple stockades and logistics had become the trump card in warfare pretty much overnight.
The 1592 Invasion of Korea by Toyotomi Hideyoshi had a contingent of 150000 men with firearms. This accounts for 25% of the whole army and outnumbered the Cavalry! Note that this invasion *also* introduced relatively modern firearms to Korea, even as the Matchlock gun was outdated when it had arrived in Japan about 50 years before!
Then, the battle of Sekigahara happened in 1600 and by 1604, the Tokugawa shogunate was firmly established, leading to the next phase. First, however, let's look at some domestic solutions.
### Domestic solutions
As wooden artillery was unwieldy, the design was adopted and increased even during the Sengoku Jidai, leading to rather massive, cannon diameter guns that had the exact same mechanism as the normal Tanegashima - and they filled the gap of field artillery and door breakers. Short variants - carabines - were introduced in that period too, but again, it was just a simple adaption of the same design with different barrel size.
A big thing that made innovations hard in japan at that time was, that there were only two types of springs known: the leaf spring - a flexible stretch of metal with maybe some bends in it - and the coil spring - a metal band that is wound around an axis. The Helical spring, which the Europeans invented in the 15th century wasn't known and its manufacturing was impossible for the craftsmen.
As new technology wasn't brought in, the domestic recombination of inventions leads to the Japanese developing domestic solutions to problems that Europe never solved for matchlocks. For example, the simple addition of a string in the front and back to stand on for night fighting, lacquered boxes around the mechanism to waterproof and hide the burning match. Designs of sheet metal appeared for sure in the early 16th century, but lacquered paper and wood are thought to have been its predecessor.
By altering the method in which gun barrels were made from boring the barrel to smithing them around some other piece of metal it wouldn't weld with, the time to make guns was reduced in the later times and it gave some of them polygonal barrels that were less susceptible to fouling. Some even had pretty modern barrels.
As a rather ingenious solution, there are records from the 1600s about bamboo tubes containing (from back to front) some flammable plug (paper or linen), the powder charge, wadding, and then the bullet. These were sealed in some way, possibly with lacquer. These cartridges would be put on the barrel and their contents rammed into it, pretty much functioning like the paper cartridge - which only was invented in 1808 - but if sealed correctly also made them waterproof. All that was needed to fire was some powder in the pan and a lit match. This sped up firing volleys compared to the same tech level European troops - according to tests made nowadays and battle accounts, the use of these devices allowed to shoot up to **6 times as fast** as without.
## Edo Period / Tokugawa Shogunate
During the Tokugawa Shogunate, there was no need for developing better guns. However, one of the early decrees was to confiscate military caliber guns from private people and lock them up for guard use.
So, the gun crafting was perfected instead of developing new solutions: the guns became more elaborate, civilians had made their guns in smaller calibers, and even matchlock pistols were developed. The small caliber rifles were pretty much hunting implements. Some of these short guns got humongous diameters (and deemed ok as they were inaccurate to hell), and some gunsmith actually made some kind of revolver with a horizontal drum. Others made hand cannons really short. They all became more decorated. But there was no pressure to innovate besides the desire for *novelty* guns as representative objects, no modern tools to make the hardworking easier. In fact, a lot of technology did stagnate in this period.
## Meji Era and beyond
We know, that the end of the Edo Period had 200 **master gunsmith** that created all guns in laborious handiwork, each of them had assistants and trainees, so it's better to assume these are workshops. We can assume that the number of gunsmith workshops was even higher during the Sengoku Jidai, when firearms came to Japan. But now, Admiral Perry arrived in 1854, disturbing 250 years of isolation. What was the immediate response of Samurai? They bought modern firearms and cannons. When in 1877 the last Samurai battle was fought, both the imperial army - outnumbering their enemies 40 to 1 - and the Samurai in Shirojama were armed with modern firearms and cannons, though the encircled defenders did field a hodgepodge of them and old Tanegahima and wood cannon artillery. The last charge of the Samurai into the advancing army on the morning of the 24th September came only after the defenders had shot every single last bullet into the sieging army.
Japanese firearms development in the following modernization was mostly import and reproduction and in the interwar period closely followed the European and American designs, often reverse engineering other countries' guns and then iterating on them. However, you should listen to [Ian "Gun Jesus" McCollum](https://www.youtube.com/watch?v=3yK0l8e0958&list=PLyvMT0kbJnvsWMtC5iJsrkkjGJ15TD2TJ) about the interwar development, though he might have the occasional pre-WWI gun in his repertoire.
## Extrapolation
If we want to keep the methods of the Edo period, we can only introduce so much in machining technology, possibly by introducing water hammer mills for smithing the barrels. But the limit on machining tech also means that we might at best turn matchlock to flintlock, without changing the character of the whole process.
The moment we want the percussion cap or the following self-contained cartridge technology, we demand quite some **machining technology** as the means to repeatedly and reliably form the caps as well as the ability to make the thin metal sheets needed for the process, which requires roller works, and quite a lot of **modern chemical knowledge** about initial explosives.
Propagation of roller works also means metal sheets are cheap, thus plate armor is plentiful and cheap, but at the same time obsolete due to the firearms. The chemistry that brought percussion caps also brought other advances, for example in the mining and farming department, increasing output. You don't necessarily *need* steam power to have bolt action, but just to have the means of making them you need strong tools, advanced alloys, and chemistry, which means you are far out of the medieval world the moment you have **percussion caps**. To stay in 'medieval' area, you can't go past flintlocks, so at best you have the above-mentioned Hall rifles in their 1819 variation, possibly with side lever.
[Answer]
There is nothing to explain, because this corresponds to real-world history; at least for revolvers. (The major stumbling block for *rifles* was the great difficulty of loading muzzle-loading rifles before the invention of the [Minié ball](https://en.wikipedia.org/wiki/Mini%C3%A9_ball). But in an alternate history there is nothing preventing their invention in earlier times; after all, they are not at all technologically complicated.)
Handmade matchlock revolvers were available in Europe since the 16th century. Here is a photograph showing the cylinder, chambers and firing "mechanism" of a German matchlock revolver from 1580.
[](https://commons.wikimedia.org/wiki/File:Drehling_GNM_W1984_ca_1580.jpg)
A late 16th century German matchlock revolver (from the Nürnberg German National Museum). Photograph by [Andreas Franzkowiak](https://commons.wikimedia.org/wiki/User:Bullenw%C3%A4chter), available on Wikimedia under the Creative Commons Attribution-Share Alike license.
[Elisha Collier](https://en.wikipedia.org/wiki/Elisha_Collier) introduced his flint-lock revolver in 1814; it began to be mass produced in 1819 by John Evans & Son of London, and eventually hundreds of them were made. (Only very few have survived; if you find one, or even better a matched pair, it is valuable.) It was used with great success by the British armed forces in India.
Such revolvers were [loaded from the front](https://commons.wikimedia.org/wiki/File:Loadseq.jpg), like muzzle-loaders. One poured a measured quantity of gunpower in each cylinder, then loaded the balls.
[.jpg/640px-Revolver%2C_flintlock_(AM_776085-16).jpg)](https://commons.wikimedia.org/wiki/File:Revolver,_flintlock_(AM_776085-16).jpg)
Collier flintlock revolver, early 19th century. Photograph by the [Auckland Museum](https://www.aucklandmuseum.com), [available on Wikimedia](https://commons.wikimedia.org/wiki/File:Revolver,_flintlock_(AM_776085-16).jpg) under the Creative Commons Attribution license.
The [Maxim machine-gun](https://en.wikipedia.org/wiki/Maxim_gun) was invented in 1884; it the first automatic gun in production. The first semi-automatic rifle was the Austrian [Mannlicher M1885](https://en.wikipedia.org/wiki/Ferdinand_Mannlicher). The [first semi-automatic pistols](https://en.wikipedia.org/wiki/Salvator_Dormus_pistol) were introduced in the early 1890. They were preceded by the manually cranked [Gatling gun](https://en.wikipedia.org/wiki/Gatling_gun).
So that in real history there is a 300 (three hundred) years gap between the first hand-made matchlock revolvers and the first semi-automatic or automatic firearms, and a 70 years gap between the first mass-produced flintlock revolvers and the first automatic or semi-automatic firearms.
[Answer]
The most important development which enabled automatic and semi-automatic firearms was the development of the brass cartridge. Before that, paper cartridges required muzzle loading and an external ignition source, whether a match, flint, or percussion cap. The brass cartridge was a single self-contained unit which enabled effective breach-loading weapons by sealing the chamber against the force of the gunpowder. The first practical center- and rimfire cartridges were developed in the 1840s, and the Gatling gun was developed less than twenty years later in 1861.
So if you want paper-cartridge, percussion-cap revolvers like Colt's but don't want any practical sustained-rapid-fire weapons available, aim for the 1840s or early 1850s.
If you want the early breach-loading repeating weapons like lever-actions to be available but not recoil-operated semi- and fully-automatic weapons, then late 1850s to early 1880s. Note that this does leave the gate open for Gatling-style externally-powered rapid-fire weapons, but it's possible that no one's quite figured out how to make it work just yet.
Either way, you'll note that firearms technology went from the flintlocks (which had been used for something like two-hundred years) to fully-automatic belt-fed machine guns in about seventy years. Your world is probably one that's seeing a similar boom in technological development, assuming it has the economic base for it.
The biggest technology jumps are flintlocks to percussion caps (early 1820s), hand-advanced to mechanically-advanced revolver cylinders (Colt's 1836), paper cartridges to brass and thus muzzle-loading to breech-loading (1850s), and then the development of recoil- and gas-operated automatics (1880-90s).
[Answer]
While the other answers provide very detailed background on the history of firearm technology, it seems they miss a point from your question.
You specify that your society has lever-, bolt- and pump-action firearms. They all depend there already being an integral brass cartridge. Thus, you need to look at the period from the second half to the end of the 19th century for inspiration.
But the important point I want to make here is this - what made self-loading rifles practical (gas or recoil operated) was not only precise machining, but also chemistry. And more precisely - smokeless gunpowder. Repeating firearms are possible with black powder, with cleaning and maintenance. Self-loading mechanisms, as 1885 Mannlicher rifle demonstrated, are neither reliable, nor practical.
So, to freeze your technical advance on the necessary level, you need some way to explain, why your chemistry is not advancing enough. It is not hard for the setting that has magic in it. Maybe they do not need to develop high explosives for peaceful and military applications precisely because magic is used there instead.
As for the rest of the technology, as I've said, you need to look at the second half of the 19th century. Precise machining definitely exists, steam engine should exist too. It is possible that your world has less available hydrocarbons such as coal and oil, that would hold back the development of internal combustion engine and synthetics.
[Answer]
## Replace Technology with Magic as Needed
What is a firing cap if not a tiny magical potion brewed by an alchemist? What is a firing mechanism except for something crafted by a talented artificer? By explaining repeating firearms as a technology that relies on magic at all of the tricky points in its production, then you can handwave away any need for metal lathes, drills, chemistry, and all the other more modern stuff you need to make a gun. Because of this you can place guns into any time in history and exclude any modern technology you want.
In a world where magic makes things easy, technology will stagnate in a lot of areas. Why invent a complex and expensive mechanism for a job you can pay the local mage to do for you. The reason guns will see so much attention, but maybe textile factories will not is that you are in a fantasy setting. Mages are rare, but ogres, trolls, and dragons are not. Your people NEED to invest their limited supply of magic into making the common folk able to defend themselves, a lot more than they need to invest railroads or what not.
So don't feel like you need to add any related technology to your setting to be able to add repeating guns. That said, one consequence you will need to worry about is what technologies repeating guns will take away. Guns go right through the best of armor. And a repeating gun means you can kill a lot of people as they try to close range with you. That means that adding this technology will almost certainly eliminate most melee weapons and armor from your setting as being technologically obsolete. At most some people will have some side swords as secondary weapons, but you can basically take all of your Barbarian, Fighter, Warrior, type classes and throw them out the window if you introduce this tech to your setting.
[Answer]
So, first, you don't have to worry about automatic weapons creeping in early because the gap between the revolver and the sub machine gun was 80 years. With a little narrative wiggling, it would be easy to stretch that to 100 or even 150, particularly if guns arrived early.
And guns could arrive early. Firearms were invented in Japan in the 13th century. If they had thrived, instead of largely being ignored by the sword-obsessed upper class, you could imagine the Japanese having manual repeating guns as early as 1500.
So, part of what you consider the minimum reasonable technological base partly depends on how you expect guns to be made. Part of how Japan got good at making guns later, in the 16th century, without having a broad industrial base was their strong class of highly skilled craftsmen.
If you assume that your world follows the same path -- boosted by the availability of magic for crafting -- you can imagine some form of repeating rifle or handgun being available even without factories, large-scale mining, advanced metalurgy, or any of the other industries that would lead to things like locomotives and airplanes. In that case, you could have your revolvers in a world that is otherwise very early 18th century, fully of sailing ships and horse-drawn carriages.
The side effect of this would be that guns would be very expensive, and not at all standardized. For example, your characters would be likely to own a one-of-a-kind handmade gun and load their own shells to use with it because they don't match anything else. Could be a fun narrative device.
However, you'll have to answer a harder question: if useful magic is available, why invent guns at all?
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So I’m currently stuck between the [peninsula-map](https://i.stack.imgur.com/shhRa.jpg) and [this one](https://i.stack.imgur.com/3OdQx.jpg) .
Between the two, which would make more sense for the federal government to have control over 17 years after zombies and a virus both wiped out 82% of mankind? What map would be more realistic if the government wanted to retake and liberate the entire country?
Also, because I know people are gonna bring it up:
* Washington was initially abandoned by the government but in the city, there were stranded soldiers, sailors, Marines, airmen, and Coast Guardsmen as well as various federal and city law enforcement officers who all formed a joint coalition to try and hold onto the city while fighting zombies, gangs, and marauders. After a year in hiding, the government reorganized itself and with whatever remaining military forces still under its command, the government came back into Washington and liberated the city.
* President Obama worked to expand federal control. He consolidated federal control in the old borders of DC before expanding the borders to one of the maps above.
* My zombies; the majority of zombies in my world are like the Walking Dead and World War Z zombies where they’re slow and move in herds/hordes whenever possible. However, they’re all capable of increasing their speed up to a regular jogging level if needed. A new type of zombies (named the “Enforcer” class) has also been discovered. They’re physically stronger than the regular zombies and also have the mental capacity of a 6-7 year old (however, they cannot speak). They’re also much more aggressive and can take control of a group of zombies. Enforcers are also able to utilize basic tactics and strategies, such as luring people in or “ordering” zombie groups to attack in waves.
* The government is based in Washington for practical and symbolic reasons. The infrastructure is already there to support a federal government and holding onto Washington gives the government legitimacy since they’re now in possession of important national symbols like the White House, the Capitol, Supreme Court, and National Mall as well as historical artifacts like the Freedom Documents.
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# Peninsula
I live in Washington DC and I can speak to the local geography. The biggest difference between the two maps is whether or not you include the waterfront of Saint Mary's county. As @Kepotx points out, there is a tactical advantage to waterfront real estate. The end of the peninsula is a state park called [Lookout Point](https://en.wikipedia.org/wiki/Point_Lookout_State_Park), which was a military base created for the War of 1812. As the name suggests, it's a great place to watch for enemy movements. Someone swimming with the ability of a 7 year old should be easy to detect. Even more important is the fact the peninsula contains [Naval Air Station Patuxent River](https://en.wikipedia.org/wiki/Naval_Air_Station_Patuxent_River) (pictured below). Both maps contain [Joint Base Anacostia–Bolling](https://en.wikipedia.org/wiki/Joint_Base_Anacostia%E2%80%93Bolling) and other military resources, but you'd be well served by having another airbase from which to launch operations.
[](https://i.stack.imgur.com/1kUw3.jpg)
Food is another reason to expand your waterfront. There's a long history of seafood in the Chesapeake Bay. DC has two beautiful rivers but you don't [necessarily want to fish them](https://www.anacostiaws.org/what-we-do/public-policy-advocacy/state-of-the-river-report-card/2019-state-of-the-anacostia-river-full-report.html).
Is there a reason that the peninsula map has that extra bit of land on the west near Martinsburg? It makes sense to have the border near the mountains/I-66 since mountains give you a terrain advantage.
# Option 3: Raven Rock
In reality, the US federal has long made plans to abandon Washington DC in the case of a nuclear war or other cataclysm. The [Raven Rock](https://en.wikipedia.org/wiki/Raven_Rock_Mountain_Complex) compound has played into many of these plans. There's even a book about it with the subtle title [*Raven Rock: The Story of the U.S. Government's Secret Plan to Save Itself – While the Rest of Us Die*](https://www.npr.org/2017/06/21/533711528/in-the-event-of-attack-heres-how-the-government-plans-to-save-itself).
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## Peninsula map
Assuming zombies can't swim, ocean is a very good border. Even against other humans, number of people coming from seas is limited by logistics, much more than in land, and it will be easier to see. You have more land, without the struggle to defend a border.
It's not only good for defense, but it is also a good source of food, river + sea will give you lot of fish.
Again, water is safe. May you trade with other cities, you would probably try to have a secure trade route, and as sea is safe, sea route may be a good thing to have.
Given those advantages, I think conquering land in the south-east until reaching the coast would be a good priority.
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If we are making the assumption that the Federal Government has survived and actually has communications and can exert control over Federal institutions across the country, then we have both a plausible starting point for a story, and an answer to your map issue: a map of the Continental United States plus overseas territories and possessions. This would include marking all surviving things like the Diego Garcia base in the Pacific Ocean to National Parks scattered across the nation. Without the ability to command the manpower and resources across the United States, any claim to be the Federal Government is a fiction - the "President" is effectively the warlord of Washington DC (regardless of which map you are using).
Indeed, other warlords who have access to better resource bases may be far more able to establish effective claims to the territories of the United States, although how much they would choose to claim and how much they would actually control is probably more a measure of their resource base, ambition and common sense. The warlord of the nearby Shenandoah Valley would have access to fairly rich agricultural lands, nearby coal deposits and a reasonably defensible perimeter against foot armies and groups with limited mechanization or numbers. His opinion of the "President" might simply be to blow off Washington's edicts, unless they have the power to actually enforce them.
And this is the real crux of the matter. Nations can fall apart without a "zombie apocalypse" if the government no longer has the power to enforce its laws, collect taxes or control its territory. The dismemberment of China in the 1800's or indeed a lot of the history of Colonialism is simply stronger and better organized forces sweeping aside weak local rulers and displacing or coopting the pre existing structures and institutions. The collapse of the USSR was similarly due to the Communist party apparatus no longer being able to enforce their edicts, or even muster enough popular support to remain in power - the USSR essentially evaporated.
If the President can still call on the Marines in 29 Palms or Pendelton, then any would be "Warlord of Los Angeles" is going to have a difficult time asserting their independence or claims to LA, the rest of California or the United States. Similarly, people moving in from Canada or Mexico are not going to be able to assert claims to "Alta Mexico" or the Oregon Territories if there is still an effective US military force willing and able to defend the borders (while local warlords might do this as well, it is for the protection of their territories, not that of the Sovereign United States).
So the actual issue with the Washington map is it only one of the multitude of places that still remain true to their oaths to defend the Constitution from "All Enemies Foreign and Domestic", and with the resources to make it stick. The larger area makes sense from the perspective that there is more farmland available to support the population, and any potential invaders will have to fight through fortified farms, local strong points and barricades if they are determined to take Washington by land (the British, of course, simply Sailed up Chesapeake Bay and the Potomac River during the War of 1812 to burn Washington), but without the control of the resources of the pre apocalyptic United States, it will only be one of a multitude of micro nations, and not even the strongest (What happens when the Warlord of Richmond decides to finish the Civil War on his terms?).
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Okay, so, first problem with both maps is that the Raven Rock Mountain Complex is not included in either. Being the US government's hiding hole in the advent of exactly the kind of apocalypse that is described, it would probably be the effective administrative capitol even if Washington DC was reclaimed and reinhabited. I buy that DC would be used as a symbolic capital for legitimacy's sake, but in a world where zombies are still a threat, and especially one where that threat seems to be increasing again, whatever was left in DC would probably get packed up and lugged back to Raven Rock, just in case.
With that out of the way-
What people are missing is the idea of a 'buffer.' If the surviving government, rather than annexing right up to the waterfront, set up a de-facto military government for the regions around DC in order to catch and pick apart the kinds of hordes that practically took down civilization, they'd be significantly more secure in their control of the District of Colombia itself. Of course, the welcome side effect is that in this period of massive instability, the capital would be significantly better protected if a popular uprising or rebellious state decided to move on them. As for farmland, I find it realistic for the soldiers to grow crops, given it has happened historically and being exposed in an open field is now a much more dangerous thing without a weapon and training.
It's defiantly a neo-feudal thing, which might not be what you're going for, but without the kind of manpower, established economic force, and broad-scale public safety against what are effectively wildlife attacks, a decentralized defense-in-depth makes a lot more sense than sending out the airplanes and tanks as a single unified army to annihilate the threats one at a time.
With zombies in particular, small, local and largely self-sufficient fortified garrisons protecting an urban center with the kind of immigration pull a resecured DC would have makes even more sense. Even when Americans in DC lacked voting rights, it still attracted a massive urban population, as any capital tends to.
With few exceptions, they will be fighting smaller, more numerous hordes, only coming together when the government detects a particularly large horde. When that happens, small and manned fortifications would be able to keep the horde distracted until help arrived, given how most zombies tend to only target a single thing at a time. This can result in some great moments, if zombies appear that are significantly more tactically-minded, leading a horde straight past the bunkers to the city of DC. The military would have probably gotten quite used to the strategy, and response times would have gotten slow after 19 years of learning how the things worked.
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There are about 1000 people, with medieval technologies, that want to build a hidden city (so other people can't find it, or with minimal chance). They must:
* have access water
* have access to food
* have enough space to live
* live in city a long time
* be able to get rid of trash and sewage they produce
* be able to bury dead ones
* be able to defend city if someone find it
What place they should chose and how they may convert that place into a city? The city may be able to expand later. Is the only option to make the city underground (hiding underground city is discussed [here](https://worldbuilding.stackexchange.com/questions/25967/how-to-hide-an-underground-city))?
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When it comes to hidden Cities you got a few options when the technologies of the rest of the world is at medieval levels. But when modern stuff like planes and satellites come in you are kinda stuck with going underground.
A Few options:
**Magic**, the go to for pretty much every problem if you are willing to use it...a magical barrier can function in any way the story teller wants it to (As long as it is kept consistent)
**Superstition**, if people believe a forest is haunted people will tent to keep out of it forming a natural barrier to hide your city...sure you got to kill a few people stupid/brave enough to ignore the "Haunted forest" signs but hey... what are a few lives in the greater picture?
**A hollow Volcano** that is only accessible through a hidden tunnel (perhaps an underwater tunnel). With artificial smoke being able to keep peeking eyes out.
The classic **underground** city is always an option. But kinda cliche (not that that is a bad thing)
On top off a steep **mountain** that is nearly impossible to climb (perhaps due to help from weather circumstances)
A **hidden valley** with hostile terrain surrounding it with a singular entrance point that can be traversed. Like the valley surrounded by giant mountains invested with monsters/animals or unbearable colds/storms but a small river going through a cave giving entrance to the area.
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# Inaccessible and with nothing of value
The Incas of Peru had hidden cities. They weren't hidden to the Inca Civilization but the Spanish never found some of them (e.g. [Machu Picchu](https://en.wikipedia.org/wiki/Machu_Picchu)). Why? They were miles away from other civilization, through jungle, and at high altitude. They were incredibly complex, built to withstand earthquakes, with little aqueducts, terraced farming and knowledge about what animals and plant breeds grew best. They also had networks of runners to deliver messages between settlements - which would give them plenty of time to get warning of danger. The Inca people are also superbly [adapted to life at high altitude (e.g. heart muscles) and eating the foods that grow well there (e.g. potatoes and starch digestion)](https://www.sciencemag.org/news/2018/11/how-people-andes-evolved-live-high-altitudes).
So have your civilization miles and miles away from other civilizations with little hermitages along the way with people that run and warn you of anyone coming. As long as you have no gold or other desirable material goods nobody will have any reason to look for you - but if they do you can either melt into the jungle with all your food and wait for them to pass through or starve, or hit them hard after they've been trecking for days through the jungle at high altitude (that they probably haven't acclimated to yet). Bonus points if your people already have genetics that allow them to live at high altitude and digest food that grows there better.
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**It is very remote and with everything of value.**
[](https://i.stack.imgur.com/2uup4.jpg)
[source](https://www.tripadvisor.com/Attraction_Review-g29218-d647555-Reviews-Hanalei_Bay-Kauai_Hawaii.html)
For example, Hawaii. What a nice place to live. Stuff grows. You can surf. No bugs. No thorns. No snakes. Clothes optional. And so freaking far away from anywhere else that once people forget the secret method of getting there (like they did), no-one will ever come.
Until Captain Cook, but up until then no-one.
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I want to have Las Vegas be a huge, bustling city in my post-apocalyptic world. I want 6,000 people to be living there, at least, and I want it to act as a trading hub in the area, with plenty of gambling, prostitution, drugs and etc.
The only problem is Las Vegas is in the middle of the Nevada Desert, so I am questioning how they would go about producing food. It’s pretty hard to grow food in the area.
So my question is: How could the people in Las Vegas produce food after the war?
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Atmospheric water generators (AWG) would be particularly helpful here. Rainwater harvesting and indoor farming would also be major contributors to the livelihood of your population.
You mentioned that your world is post-apocalyptic. So, are they the only people left (at least in the United States)? Is national trade available? If not, then your people should have a notable focus on canning and preservatives. Some foods will not be available year-round even after taking that into consideration. Somewhat secondary, you can factor this into the seasonal economy of your population.
Another strong consideration are GMOs. Plants can be modified to increase the amount/size of the fruit. They can also be modified to withstand the harsher climate of the desert. Your population can even create entirely new species of plants that never existed before. Animals can be modified to breed faster and have larger broods.
Ideally, for this community to be sustainable, they would have to be resourceful and have a fair knowledge of agriculture, engineering and science.
Additionally, here is a very short list of just a few plants and animals that have evolved to endure arid/semi-arid environments. I just wanted to give you some valid examples:
**Plants**
Pumpkin
Squash
Corn
Potato
Spinach
Beans
Broccoli
Carrots
Radish
**Animals**
Lizard
Camel
Coyote
Snake
Deer
Sheep
Tortoise
Rabbit
Snake
*considering the fact that the world is post-apocalyptic, there is a decent chance that some animals not normally found in the Nevada desert might migrate there*
Also, for more diversity, you might want to consider extending your population pass the Sierra Nevada and Cascade mountain ranges. One of the main reasons for any group to venture out and migrate is because of a lack of food. That's why there's very few large cities in deserts. Historically, people gravitate to areas that are abundant and rich in resources, which are usually areas that are close to the ocean. Is there a reason why they're stuck there?
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**The Ideal:**
There is farming near Las Vegas.
For example, this kind of hydroponic [indoor farm](https://news3lv.com/news/local/veggies-grown-in-nevadas-massive-indoor-farm-is-now-on-sale-to-las-vegas-locals). This kind of farming can be done in the casinos themselves. You don't need 20 floors of hotel rooms: just convert as much as possible to indoor farming.
Your gangsters and johns are simply going to have to be part time gardeners, because hiring farms hands or feeding slave labourers is going to be expensive.
This could work if the farming infrastructure were already in place before the Pockyclypse.
**The Problem:**
More than likely, casino crews, crime lords, drug mongers and prostitutes aren't going to be interested in gardening or farming of any kind. Their kind of subhuman existence doesn't really elevate one's horizons much above the gutter, as it's all about instant gratification, power and money. They're going to need a different solution.
**Reality Check:**
Realistically, the baseline solution for this kind of dystopic society will be to do what crime dens have always relied on: *importation & crime!* Whatever is needed that can't be found, produced, or made locally will have to be imported. You said Vegas is to be a trading hub, so long haulers bringing goods and food and water will likely stop in the city. Long haulers wanting to pass through the area will be diverted to tithe their hauls to the bosses. And while that's happening, they might try their luck in the Casino! Food will have to be hauled in from whatever local farms there may be or else imported from a distance. Since this is postpockyclyptic and shipments may not be regular, your Vegian thugs will probably have to go on long haul raids to bring back food and water to the metropolis.
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The Egyptians and Southwest Mesoamericans practiced Channel Irrigation. You could dig channels into the banks of Lake Meade and then use the Hoover Dam to flood the lake and the channels, bringing water and mud to the desert. You could then grow plenty of corn in the muddy channels. There were ancient cultures doing this successfully for centuries in the southwest before they died out mysteriously.
Egypt was so stable and successful because the Nile flooded regularly, but the Mobster-Pharaoh of Vegas could flood the Colorado River at will by ordering floodgates on the Hoover Dam be closed. In the off-season, farmers upriver would maintain the irrigation system in a massive public works campaign. Farmers would float their barges full of corn down the Colorado River to Vegas to sell crops, pay taxes, and acquire gambling addictions.
People living downriver would be upset that they get less water when the river is dammed up and fight for their water rights. A Mobster-Pharaoh might become a living river god like the Egyptian Pharaoh. A bad Mobster-Pharaoh may become decadent, preferring to use the dam for electricity and neglecting his duty to make the river flood.
this link has good info on ancient irrigation:
<http://www.waterencyclopedia.com/Hy-La/Irrigation-Systems-Ancient.html>
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**Farm the golf courses.**
Las Vegas is surrounded by golf courses. A golf course is about 150 acres of turf farm. These have already prepared soil to allow grass to grow and already have irrigation systems which might be more or less salvageable in your post-apocalypse. They can bring in more soil from the abandoned yards and parks. They can use windmills to bring water up from the Colorado.
These golf courses will be on the outskirts of town with your condensed population for 6000. That is fine. You can definitely grow corn, beans and squash on irrigated golf course lands in Las Vegas. Meat can be raised in greener areas and brought in on the hoof.
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There is no problem with what you're proposing. Lake Mead and the Colorado River are reasonably close to build irrigation system from if they don't already exist and 6000 people isn't very large to try to provide for when you're on a lake like that.
The most that you're going to have to do is build an irrigation system and move "Las Vegas" closer the water supply which is inside what is called the City of Paradise.
The biggest problem that you'd face is really that at some point someone's gonna cut off the supply of water from the Great Lakes and you'll get famine and a huge die off which then leaves a bunch of corpses lying around. Once you get past that you might get a lot of fertilized land from that and that should get you all the food production you'd ever need.
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A lot of what your farming capabilities depend on what has happened during the apocalypse. If the irrigation system or water supply system has been damaged, it is unlikely that farming would succeed. For example, if in the apocalypse Hoover Dam was destroyed, then delivering water to thousands of people as well as farms and other industrial purposes would be difficult. However, it is also worth noting that only 90% of [Las Vegas's water supply comes from the Lake Mead](https://www.lvvwd.com/water-system/where-your-water-comes-from/index.html), which is a large percentage, but your planned city population is only 6,000, which is, after a quick, back-of-the-envelope calculation, quite a bit less than 1% of Las Vegas' total population. The remaining 10% comes from groundwater, and if we also assume that your people will be able to get at least some water from the Colorado River, I assume that's sufficient water for your city.
As for conditions for planting food or keeping livestock, I imagine that hydroponics would be a good answer. Livestock would primarily need land to graze on, and that would likely be scarce. However, there is some hope, [like this former pig farm in North Las Vegas](https://knpr.org/knpr/2016-03/rc-farms-owner-sell-north-las-vegas-pig-farm) which fed their pigs with leftover food scraps from the Strip. It closed a few years ago, but it's easy to see bigger projects popping up similar to this one. Overall, the farming situation does look optimistic for a smaller Las Vegas, and the trade coming through the city will surely increase the availability of food as well.
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The only problem with Las Vegas is water.
The land is fertile enough if you can only irrigate it, and the irrigation systems are all in place.
Now, if 99% of the population are conveniently removed (currently 600k), you have a lot less swimming pools and jacuzzis to fill and a lot more water for efficient water-conserving farming.
So long as whoever sets up the agriculture system knows what they are doing and has sufficient labor to get it going, there is no reason why the place should not feed itself with a more advanced version of what the original inhabitants of that part of the world would have lived on -- maize, squash, beans , plus assorted livestock.
Depending on the type of apocalypse, having such a tiny population means you should be able to supply a certain amount of your meat needs from hunting.
Er, how to do you feel about cannibalism for any unfortunate travelers…?
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The setting is a post-apocalyptic Earth, a few hundred years after a "world-ending" war. What remains of humanity is beginning to emerge from Fallout-esque shelters, but (more importantly) magic creatures who were formerly in hiding during modern times have also begun to re-emerge from humanity, albeit altered now with so much human blood mixed in over the centuries.
The new mythics (as they're called) have built up their own societies at roughly medieval levels of technology but with some knowledge and information of how the world was before. Scouts frequently find surviving documents and such in old city ruins. Recently, one of these colonies has found the blueprints for an 1873 Springfield Trapdoor Rifle and decided to recreate it for purposes of hunting.
Magic is also a thing that exists among the new mythics, however it's not convenient to cast in a rush as it requires a magic circle to be drawn (or carved or other means of marking) onto an object before the individual can pulse their own magical energy through it to let it manifest. Permanently marking something isn't commonly used as the magical energy can wear away at weaker materials, so this practice is typically only used to essentially "enchant" metal-based objects such as swords or tools. This drawback also discourages people from tattooing circles on their own bodies, except for use in healing magic.
**My question is thus:** An individual who specializes in fire-based magics has received a newly-recreated carbine version of the aforementioned rifle. I want to know if, considering how the bullet cartridges work, she could somehow use her fire magics to either enhance the gun's power/range capabilities or to fire the rifle if the hammer was somehow disabled. **Basically, can fire magics make an unmodified\* rifle work better or would the ammunition have to be fundamentally changed for magic to be useful with it?**
\*(not counting the implementation of magic circles)
**Key Points Summarized:**
* The gun in question is a Carbine 1873 Springfield Trapdoor Rifle recreation
* Magic works via putting one's own magical energy into a magic circle
* The circle would have to be carved either onto the gun's barrel or onto individual bullets
* The individual in question specializes in fire-based magic
* I'm aiming for minimal changes in the fundamental design of the rifle itself, but I am okay with changes to bullet design if it would facilitate the use of fire magic on it
* No is a perfectly acceptable answer, but reasons why must be given. If I as the writer don't understand why it doesn't work, I can't explain why it would work within the story and I can't find good ways to work around it.
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**Yes**
There are ways that fire magic can be used to enhance a rifle. A bullet travels by way of explosion, and increasing the power of the explosion increases the power of the bullet. It's possible to engrave fire magic on the end of the bullet and, instead of using a striker to hit the primer, the black powder is detonated via magic fire circle, and possibly the fire circle is a bit stronger so it's a more powerful blast, and thus a more powerful bullet.
And now I pose the question: Do you *need* a more powerful bullet? Stronger is better, sure, but while the Model 1873 did have a rifled barrel, it wasn't *that* accurate. There are two main advantages to be gained by increasing a bullet's power: range and penetration. But, like I said, a rifle made in 1873 isn't accurate enough to gain anything major by way of increased range, and I'm not sure what you're fighting against that a normal round can't punch clean through, given the time era you're dealing with. So the increase in power doesn't actually do much for you.
The two greatest problems that such a rifle had was aim, which you can't help with using fire magic, and reloading speed, which you also can't have help using fire magic. The aim, as I said, isn't anything compared to a modern rifle and thus improving the range isn't useful, except in mass volley. You *could* do that, I suppose, but it's your protagonist you're dealing with who is presumably alone. The second is the rate of fire, which, given that this is a breechloading rifle, isn't great. And it can't be improved at all using fire magic.
The best use for fire magic, therefore, is a rather depressingly mundane use - a primer substitute. A bullet cartridge used in the 1873 Springfield (and in fact the vast majority of cartridges) would have a primer on the back of the bullet which is struck to ignite the gunpowder within the round. And black powder is a lot easier to make and manufacture than a bullet primer, given that the chemical ingredients for the latter are a bit more exotic. Given that, it might make sense that your magic user, who is adequate enough to make her own cartridges, just ignores primer when making her own bullets. Don't bother with making the bullets that much stronger - just focus on making the bullets easier to make.
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## Yes
I'm going to make some big assumptions about what a fire specialist can do. These may not be valid in your case.
* Auto-aiming : the magician can inscribe a circle on the front edge of the muzzle (or maybe on the sight) that auto-magically lines up the rifle to a target of the magician's choosing (the magic is drawn to body heat like a compass to a magnet)
* Easier cartridge loading : a magic circle in the breech could light empty copper casings, replacing the need for gunpowder. The magic could even pack more punch into the shot than gunpowder ever would have. Maybe, in a pinch, the cartridge can be done away with and the wizard can muzzle-load anything he or she can get his hands on.
* Stronger shots : a magic circle on the muzzle could strengthen the rifle against detonation, especially if the wizard plans on doing anything reckless like muzzle-loading the weapon with found debris. This could be paired with more explosive power in the breech.
* Bio-metric safety : the wizard can enchant the trigger ring to burn anyone but the wizard trying to use the weapon.
* Kill switch : the wizard could also enchant the breech to quench fire, essentially disabling the weapon in the event it was ever pointed at the wizard. This could be automatic, so that even if the wizard was unaware his weapon was being pointed at him, the weapon is put in a "safe" mode.
* Recoil compensation : circles could be inscribed along the outside of the barrel that, when the weapon is fired, generate magically-quick-cooled exhaust gas recoil compensation. Allowing even more power.
* Rod ammo : if using magic to add weapon power, strengthen the barrel, aid aim, and dampen recoil; the wizard could go for longer rounds, which would do a better job against heavy armor.
* Enhanced bayonet : all sorts of things could be done to the bayonet, like magically super-heating it.
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If the wizard could enchant a projectile from that weapon to melt upon contact with something, that could be a severe advantage, although the projectile would also be extremely painful (I do not know whether your mage will consider that good or bad.)
Also, a self destruct in that weapon could be used: A magic circle could be drawn upon the wood of that rifle, and the wizard could remotely cause the wood to burn, thus rendering the rifle useless. The opposite could also be done, and a circle could be drawn that prevents the wood from burning.
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I'm concerned for their ability to make the original ammunition. "Smokeless powder" is a hell of a lot more complex than black powder to produce. Black powder leaves a corrosive particulate residue. The improved propellant allows for a vastly increased rate of fire because we no longer have to clean the barrel after every shot.
On one hand you could hand-wave hand-wave "Alchemy"...
On the other hand, if you can superheat the air and keep the round and barrel relatively cool, you don't need a case or gunpowder at all. Congratulations, you've reinvented "caseless" ammunition. This can allow for a much simpler mechanism. Heck, switch to muzzle loading a long metal tube with one end capped. They wouldn't even need a trigger, just magic.
One of the big problems with modern caseless ammunition is that it turns out that hot brass being ejected from the chamber makes for a pretty good heat sink. But if heat is your bitch, you don't have that problem.
So is your character have "combustion magic" or "heat magic". Big difference. Fire needs three things: Heat, fuel, and oxygen. Which of these elements can your fire magic character create? Just the heat? All three? "All three" or "heat and fuel" can ditch the propellant and make their own explosion inside the barrel.
But if your character can only create heat, then they can set off the propellant without a trigger.
Now if you have some control over when that heat is applied, you can create a bullet that explodes into gas one second after it leaves the barrel. Even more control might allow "1/100 of a second after impact", so you don't get surface explosions, and you don't get rounds exploding after they've punched all the way through someone or some*thing*.
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In 1534 the act of of supremacy passed by the solidified the break from the Catholic church and made the king the supreme head of the church of england. Although there were many reasons for this going back centuries, one that forced the issue at that moment was the Pope refusing to release king Henry from his marriage vows. This was the act that broke the schism and let to Catholicism being less dominant in England.
In this alternate history, I would like things to play out differently. A form of polygamy is allowed, but limited to the noble class to prevent it from going out of control. This would allow Henry to stay married to his barren wife while marrying another who could give him an heir. While this won't prevent the schism by itself, it will by the church some time to set about making peace with Henry to keep Catholicism dominant. However, there are several obstacles to this that prevent it from becoming the norm.
The purpose of an ecumenical council is to define doctrine, reaffirm truths of the Faith, and extirpate heresy. The Pope would have to steer this group into accepting this radically different direction in order for it to become a social norm. By this time, Christianity had a long abhorrence to polygamy, associating it with barbarianism. In the civilized world, it was expected that a man would take one wife. This has been the accepted practice wherever Christianity was present, and any change in this tradition would likely be met with uproar. In addition to this, it is a basic doctrine that both man and woman are equal in the eyes of God. To have separate rights for the wealthy would appear anathema to Catholic faith.
An example of polygamy in Christianity would be some sects of Mormonism. however, Mormons are often considered a fringe Christian sect bordering on heretical, and not wholly accepted by others as a legitimate denomination. I would like to make limited polygamy and acceptable norm while leaving the faith somewhat recognizably Catholic. I also need to limit the backlash as much as possible. Is there a way to make this happen?
[Answer]
**It’s Been Done Before**
The Church of Jesus Christ of Latter Day Saints, or Mormons as more popularly known have [a history of polygamy](https://en.m.wikipedia.org/wiki/Mormonism_and_polygamy) Joseph Smith claimed to be a prophet, and he and his successor Brigham Young taught that God had ordained plural marriage (polygamy). They used a mixture of new revelations claimed by Smith and also Old Testament Laws on [Concubines](https://en.m.wikipedia.org/wiki/Pilegesh) and [Levirate Marriage](https://en.m.wikipedia.org/wiki/Levirate_marriage)
Several notable figures in the Old Testament were Polygamists, with Moses, David, and Solomon all having multiple wives and concubines.
So the Pope in your scenario needs to argue that since there are laws in the Old Testament that concern the practice of having multiple wives, that several exemplary figures in the Old Testament practiced polygamy, and therefore there is a biblical precedent for allowing a king to have more than one wife, particularly if it is for producing an heir
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Given NixonCranium's Excellent Answer which addresses the "conformable with Sacred Scripture and Apostolic Traditions" limitation, this should fall neatly into the realm of [Papal Infallibility](https://en.wikipedia.org/wiki/Papal_infallibility). The Pope doesn't need to convince the council of anything. He just needs to inform them of this newly revealed truth.
[Answer]
Christianity inherited its initial social structure from Judaism, which allowed polygyny (though not polyandry) - it occurs several times in the Torah, and is never forbidden at any point. While it could be argued that the monogamous *ideal* was present from the start, Adam and Eve being the archetypal couple (forget the apocryphal Lilith for now), several prominent and positively-regarded Biblical figures had multiple wives: Abraham, Jacob, Moses, David, and Solomon to name a few. There is a verse that forbids a king from "greatly increasing" his number of wives (or horses) but the exact amount is left vague. (Solomon, whose partners numbered in the hundreds, is sometimes criticized for this.)
The shift in Abrahamic religions towards and away from monogamy has gone back and forth over history, with several early hints to monogamy as an ideal but not explicitly forbidding polygamy until later periods. (Generally every verse that is used as evidence towards the monogamous ideal could be just as easily interpreted as forbidding *extramarital* relationships - which is what Christian polygamists, such as some Mormon sects, argue.)
In practice, religious ideology has largely followed sociological paradigms. Feudal societies tended to follow a "winner take all" structure, where the difference between the wealthy (who had abundant resources) and the poor (who barely had enough to support themselves, let alone a family) was far more significant than it was in periods with a larger middle class. In such societies there is a natural tendency for wealthy men to take multiple wives, both because there was an abundance of women seeking men who could support them, and having large numbers of children was a good way of maintaining control over large plots of land. Using marriages to cement treaties between landowners was also a common practice in feudal societies, and naturally this paradigm favored polygamy.
Periods with a larger middle class tended to favor a monomagmous structure, since middle class (skilled-labor) families function best when a family's resources (especially time, money, and energy used for education) are focused towards a small number of children. Religious practice and ideology often enforced this tendency when it occurred. Modern societies tend to have a much larger middle class compared to earlier ones overall, so monogamy tends to be the ideal, but this could easily be reversed if social structure changes back.
To make the concept of polygamy become mainstream again, simply increase the split between the wealthy and the poor.
[Answer]
# The Pope loses his secular power struggle with Germanic kings, or never engages in it in the first place.
The whole reason why Christianity bans polygamy has nothing to do with religion, and everything to do with secular cultures and power struggles. As IndigoFenix notes, Christianity first got its monogamous slant from the Hellenistic culture of the Roman Empire; even in the New Testament, the only verse banning polygamy only banned it for priests/church elders.
Then in the Middle Ages, when Germanic tribes and kings started moving in Europe, they brought with them a tradition of polygamous marriages. The Catholic Church got into some secular power struggles with them, and decided that one of the better ways to do so was to control the institution of marriage, and thereby gain a degree of control over the monarchies; as a part of doing that, they banned polygamy as a way of asserting control.
So, for that not to have happened, either the Catholic Church lost this particular power struggle, or they decided not to try to exert this kind of control in the first place.
[Answer]
All religions adapt to social and environmental conditions, given sufficient time, otherwise the fade into obscurity.
If your society is faced with a serious decline in male fertility -- may be a virus that inhibits motility of sperm or a contaminant in drinking water -- and if it has gone on long enough for people to figure it the effects -- but not necessarily the cause -- when faced with a severely declining population, the church might find reasons to doctrinally encourage polygamy.
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Aristocrats could and did have both wives and mistresses. In that sense, you already have one man simultaneously involved with multiple women; the problem is sorting out the legal questions, such as inheritance. What if Henry pushed Catherine into adopting and therefore legitimizing his son by another woman (either Henry FitzRoy or a fictional child), and both the Church and the rest of the nobility supported the move in the interests of political stability? (You see adoption occasionally in the Middle Ages and Renaissance using Roman legal models.)
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In a world I’m designing, a group of Homo Habilis, Australopithecus Afarensis or even Paranthropus migrated into a northern Scotland environment becoming Trolls. These are not D&D trolls, but something else. I have a number of basic characteristics for these beings, and am wondering whether these characteristics are plausible.
**The basics of my trolls**
* Can range in height from 143.2cm (4ft 8in) to 228.6cm (7ft 6in) tall
* Are mostly covered in a thick, coarse hair. Like that of wolverines
* Have an average have a life span of 150-170 years (barring major injuries)
* Can fully regrow missing limbs in approximately 1025-1095 days.
* They are not significantly prone to cancers
* Have large noses, as well as cow-like ears
* Their diet consists primarily of plant matter, though they scrounge a certain amount of protein from insects and carrion and will rarely scavenge dead animals
* Have very sensitive eyes and are nocturnal
* Are mostly solitary but do form groups during the colder months
* Have sloth like claws for digging up roots and peat
* Have gorilla-like strength
* Have very rudimentary tool use
**The question**
* How realist is this?
* Could an early hominid like Homo Habilis or Australopithecus Afarensis even live long enough to evolve into these trolls?
* Are there any other traits my trolls would need?
* and what evolutionary pressures might lead to them
## Edit:
I guess I should have been more clear with
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> Are there any other traits my trolls would need?
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what i meant to say was are there any other traits that my trolls would need to survive in northern Scotland?
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I think most of the traits you want are plausible for a hominid species, either due to a presence in closely related species or because we can associate them with a (stem cell based?) ability for continuous re-growth.
Given that some of the traits you envision, make them more comparable to great apes than hominids, I think something like that (or maybe a common ancestor) might be a better origin species for natural evolution than hominids.
As for comments on specific points:
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> Can range in height from 143.2cm (4ft 8in) to 228.6cm (7ft 6in) tall
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This range seems a bit much to me if we assume that it all applies to fully grown adults (body plans need to be very tightly controlled, so size variation is usually not very big). It would probably make more sense that your trolls never stop growing, even after they exit the growth spurt of juveniles. Such continuous growth could be caused by increased basal levels of developmental programs / stem cells (which can also explain some other traits you want).
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> Are mostly covered in a thick, coarse hair. Like that of wolverines
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I imagine this similar to a gorilla / great-ape, so most the genes are probably already/still there.
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> Have an average have a life span of 150-170 years (barring major
> injuries)
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A bit higher than other mammals of that size, but given that the trolls seem to have increased health/regeneration this seems fine.
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> Can fully regrow missing limbs in approximately 1025-1095 days.
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This is a tricky bit, because mammals usually don't regenerate tissue. However, it's definitely possible and - like the continuous growth - could be explained by a basal level of developmental/growth programs, which would also explain why it takes so long (even if those programs get more prominent when a full limb needs to be re-grown).
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> They are not significantly prone to major disease
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Like the other answer already mentioned this is not very well defined - diseases come in terms of pathogens but also issues of the own body. For the latter limb/organ/... regeneration abilities would help a lot (i.e. the heart could over time recover from a stroke), while the immune system is of course needed against everything else.
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> Have large noses, as well as cow-like ears
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Noses should be fine, the ears are more tricky (the other answer also mentioned that), as most hominids or even apes/monkeys have quite human like ears.
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> Their diet consists primarily of plant matter, though they scrounge a certain amount of protein from insects and carrion and will rarely scavenge dead animals
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This seems similar to the diet of great apes, so it should be sufficient for an hominid of that size. However, northern Scotland will not provide nearly as much food as a jungle. It may be an explanation for their solitude life style though - they need big areas to find enough food.
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> Have very sensitive eyes and are nocturnal
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One often comes with the other and shifts to or from nocturnal life styles have happened quite a few times during evolution.
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> Are mostly solitary but do form groups during the colder months
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Most hominids (but also monkeys or apes) are quite social, so this is a bit untypical - it could however be explained by other factors such as food availability in scotland (see above).
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> Have sloth like claws for digging up roots and peat
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Most hominids/monkey/apes don't really have claws so this is, again, untypical. Elongated nails are fine, but real claws seem a bit much to me.
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> Have gorilla-like strength
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> Have very rudimentary tool use
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Both of these are fine and in line with the species origin / similarity.
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> Can fully regrow missing limbs in approximately 1025-1095 days.
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The regeneration of lost limbs seems slightly suspect, if only because there aren't a whole lot of other complex animals which exhibit such features. Newts and axolotl show that it can be done by tetrapods, at least. Quite why such a complex and useful feature woudl have arisen in your trolls in the absense of some kind of evolutionary pressure is anyone's guess (by which I mean, yours to handwave). What hunted the trolls? What happened to it?
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> They are not significantly prone to major disease
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...is a sentence absolutely chock full of weasel words, but I almost feel that this is *less* plausible than limb regeneration. "Disease" covers a vast range of very different pathologies, and for your trolls to be somehow immune to whole swathes of these seems pretty peculiar, given how different eg. genetic illness is from parasitic illness is from viral illness is from bacterial and so on and so on. They may be more prone to cancer than regular folk, given their regenerative powers. Things which improve cancer resistance are likely to interfere with the complex set of cellular changes and rapid growth associated with newt-like regeneration.
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> Have an average have a life span of 150-170 years (barring major injuries)
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I think there's a tradeoff to be made between lifespan and regenerative powers, due to the risk of cancers. I'd almost expect your trolls to have a shorter lifespan than humans, for exactly that reason.
Handwaving in a high resistance to disease *and* cancer *and* regenerative powers would help explain long lifespans, but it is stretching the bounds of plausibility somewhat. If the long lifespan isn't critical to your setting, I'd be tempted to drop it.
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> Have large noses, as well as cow-like ears
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Cows inherited their cow-like ears from their ungulate forebears. Why would a primate have them? You can just handwave it in, of course. I guess there's no reason not to. Just seems a bit odd, and unnecessary.
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> Their diet consists primarily of plant matter, though they scrounge a certain amount of protein from insects and carrion and will rarely scavenge dead animals
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You should have a look at the sort of vegetation that grows in the north of Scotland, and think about the calorific demands of big brains and regenerating limbs. Growing seasons are short, and fruit species are limited in number. I would expect them to have bear-like diets... quite omnivorous, generally happy to eat carrion and sometimes even predatory. I'd expect them to eat shellfish, and probably fish too. Eggs would be another thing they would be good at finding, in the right season.
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> Have sloth like claws for digging up roots and peat
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> Have gorilla-like strength
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> Have very rudimentary tool use
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Tools are for species who have brains but aren't well equipped for various food-acquisition tasks. Being really strong and possessing great big claws rather obviates the need for most primitive tools, because you've got the stuff you need to hand already. What would they even need tools for? Moreover, if you *do* have great big claws, your manual dexterity is going to be impaired somewhat, making you less able to use tools if you somehow felt the need to.
At the very least, I'd lose the claws. At least then there's a good reason to dig and poke with sticks and smash things with rocks, etc.
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> How realist is this?
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Seems OK, I guess. There are a lot of complex traits that your trolls will have evolved all by themselves, and you have to wonder why they'd do that and where the evolutionary pressure would have come from.
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> Could an early hominid like Homo Habilis or Australopithecus Afarensis even live long enough to evolve into these trolls?
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If you wanted them to, why not? The tricky bit will be handling their encounters with later hominins, and explaining why they survived the encounter when all the other members of *homo* did not.
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> Are there any other traits my trolls would need?
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For what?
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A big problem is that there is no evidence of primates of any type indiginous to Europe from 35 Million Years Ago and the colonization of southern Europe by H. Erectus H. Neanderthalis and those little trouble making H. Sapiens sometime between 270,00 and 215,000 years ago. Prior to that, all Hominids and close great ape species were largely confined to Africa and other nearby territories. Hominids didn't make it to Scotland until about 12, 800 years ago during an ice age.
Your two species were omnivors, but largely subsisted on fruit with some meat additions from time to time, mostly from carion and leftovers from carnivors and H. Habilis did not have the upper limb development that made it capable of the type of hunting that would make later members of the genus move to further north ranges (persistence hunting and ranged attacks) (upright stances at this time would be defensive only, allowing H. Habilis to see predators over tall grasses). Tool Use was not offensive at this time. Colder European climates would make their essential fruit and vegetation dietary components seasonal and they were not hunters capable of surviving in winter.
Again, keep in mind, Humans are the only primate that lived in Europe at all past 35 million years ago (the other primates were wiped out in an Impact Event in Siberia that lead to a minor mass extinction... you don't hear about it because of the two impact events that created a mass extinction the K/T Impact was, as many important scientists would no doubt note, a hella lot bigger and deadlier). Primates in Europe is a very recent nostalgia trend in terms of evolution and even then, humans aren't adapted to living in Europe yet (what... it's been almost 300,000 years: Can you grow your own fur coats and not steal it from other animals? No? Didn't think so.). Hell, your guys were from about 2.1 million years ago and they never got into Arabia.
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If you had a device, similar to a Stargate, but that allowed seamless two way transfer, and that could be moved (You could essentially strap a rocket on it, and fuel it from Earth), you could just leave it in orbit, and *shove* a satellite into orbit, or "anchor" the gate on a space shipyard, and funnel materials and components, and manpower, through it.
Let's say you want to build more traditional science fiction space ships (Crew quarters, command bridges, engines, science stations and scanners, the whole Star Trek-shebang), and you can't pass a whole one through the gate; the gate is too small, and making one big enough is cost prohibitive.
But just as you can have a micro gravity space shipyard in orbit around Earth, you could also have a low gravity launch facility and shipyard on the moon.
Would the low gravity of the moon, be of benefit to a large scale ship building program, or would it just be better to skip the middle staging ground, and build the ships already in orbit around Earth?
Assume that no artifical gravity technology exists (A rotating shipyard is acceptable), and that the presence of a new Stargate on a newly built ship means fuel reserves can be kept low until in orbit around the moon, and launch cost itself is therefore a minor benefit to keeping the construction in orbit.
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I'd be doing all my large-scale construction and assembly in low Earth orbit.
This has three major advantages. Firstly, although you're no longer protected by the Earth's atmosphere you *are* still protected by its magnetosphere, whereas the moon is mostly not. Secondly, lunar dust is an absolute *nightmare*. It gets everywhere, it has all sorts of unpleasant electrostatic effects, it is sharp and abrasive, probably toxic (and probably carcinogenic, too) and all these features make working on the moon sound extremely unappealing. This sort of dust is probably present on other airless bodies in the system, too... Martian dust will also be extremely fine and abrasive but with the added bonus that it is full of reactive chemicals, too.
Finally, in the event of a problem with the stargate, Earth is *right there*. Radio communications are easy, round trip delay times are low, and you can even have re-entry lifeboats if needs be. All good things.
Exceptions can be made for stuff that is intended to be deployed a long way away. You may as well build your starships in the Oort cloud, and ships intended for use in the outer solar system *in* the outer solar system and avoid all the hassle of flying them out there in the first place.
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You might also consider the fact that having the ability to create flying stargates largely removes the need to muck about in space in the first place. Why go up there? It is full of things that'll kill you. Fly your stargates somewhere nice, then get out at the other end. Much safer, comfier and probably cheaper, too.
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From a purely structural point of view, building a spaceship in microgravity means that the structure will have to cope only with the intended acceleration assumed during the design.
Building it on a body with its own gravity means that it will have to be factored into the calculation for the structure, potentially adding weight but in any case resulting in additional design time.
All the rest equal, then, building in microgravity saves design time and is to be preferred.
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Lower gravity has many advantages. Primarily, it is easier to move things around, and you don't need (much) scaffolding, and structural integrity of whatever you are building is practically no issue.
Yet, since all that has been mentioned, i would like to look at the flipside of the coin: provided you have humans working on the construction of your vessel, they might actually prefer somewhat higher gravity. First, it's what we are used to, so you need less training than when working in micro- or zero gravity. and second, if you want to tighten a bolt or use a hammer, it is extremely practical if newton's third law would not send you flying away every time you paid a bit less attention than you should.
That means, the higher the gravity, the more use a worker can make of his own mass.
Think about pushing a door open: That works fine, because you can transfer forces into the ground, which in turn is possible because gravity pushes you to the floor, thus providing enough friction between the floor and your feet.
Without gravity, you would need to hold on to the wall in order to push the door open, meaning you need two hands for the job.
So, as with every engineering issue i know of, there is not one clear and correct answer, but you have to balance the pros and cons.
You want gravity as low as possible to facilitate lifting things and preventing them from falling down, yet you want enough gravity to keep things together and give your workers something to stand on.
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There is a concern that's been brought up only recently--steel and concrete buildings are environmentally wasteful. In further clarification, they waste away too much greenhouse gases. And considering how many steel-and-concrete skyscrapers currently exist *worldwide*, that is incredibly damning. Which is why some people are nowadays to the idea of a "plyscraper"--a structure made primarily of cross-laminated timber (CLT), which, unlike steel and concrete, ***stores*** carbon dioxide.
However, the focus of this question is the one recurring foe of any high-rise structure--***gravity***. Draw it too tall, and the force to end all forces would crush the structure down, which is why Shimizu won't be using conventional materials when they build their Mega-City Pyramid.
The shape of a building also plays a factor because of weight distribution. Shimizu was on track with a pyramid shape, as the far wider base makes the overall structure more stable, and most archaeologists can agree that the massive Tower of Babel, if it existed, wouldn't be a tower but a ziggurat, which looks different from a pyramid but still has the same principle.
So in the event of building a ziggurat out of both CLT and bamboo, **what is the biggest (in regards to base width and height) that it can be without crushing under the force of gravity?**
[Answer]
I did some search for the world's largest wooden structures. Some sources point at the [Kondo](https://en.wikipedia.org/wiki/H%C5%8Dry%C5%AB-ji#Kond%C5%8D), a.k.a. Great Buddha Hall as the largest one. It's about 18.5 meters tall, and 15.2 meters wide.
Technology made it possible to build bigger wood structures. The [Superior Dome](https://en.wikipedia.org/wiki/Superior_Dome) in Michigan is 44 meters tall (143 ft) and 163 meters wide (536 ft).
A company named Tamedia has [a wooden building that is 50 meters tall](https://www.dezeen.com/2015/07/08/tamedia-timber-framed-office-building-zurich-shigeru-ban/) (164 ft).
The [Brock Common Tallwood House](https://sustain.ubc.ca/research/research-collections/brock-commons-tallwood-house) is 53 meters high (174 ft).
But the cake goes to this one:
[](https://i.stack.imgur.com/ZbzzU.jpg)
Source: <https://wandering-through-time-and-place.com/tag/tillamook-air-museum/>
This is the Tillamook Air Museum. It was initially a hangar for zeppelins.
[](https://i.stack.imgur.com/cC7Jk.jpg)
Source: same as above
This structure is 58.5 meters tall (192 ft) and 90 meters wide (296 ft). This is the tallest one I could find.
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For state-of-the-art in timber buildings, you can see that a lot of people are talking about (and even planning) plyscrapers that are [over 300m tall](https://edition.cnn.com/style/article/wooden-skyscrapers-timber-trend-catching-fire-duplicate-2/index.html). The super-tall wooden building industry isn't exactly in its infancy, but there isn't a huge amount of experience out there, and it seems like things can only improve from there.
For a very handwavey maximum, consider the compressive strength of CLT ([say, 50MPa](https://link.springer.com/article/10.1007/s10086-014-1435-x)) and its density (say, [480kg/m3 for spruce](http://www.greenspec.co.uk/building-design/crosslam-timber-performance-characteristics/)... bamboo will likely be a lot denser) you'd get a simple height limit of ~10.6km. That obviously only applies to a pure CLT column with literally nothing else in it that would make it a building, and simplifies things far too much, doesn't consider the usual serious safety margins and so it probably quite an overestimate. Iit is probably out by an order of magnitude, but not two, as can be seen from already existing and currently planned wooden buildings. Whilst the number itself probably isn't very informative, it does suggest that the materials in question are certainly strong enough for most purposes. If you *really* wanted me to put a number on it, I'd say 1000m, but it is entirely possible that future advances in wood composites and the use of other materials in the construction could make it larger than that.
There's no real practical limit to the girth of a building; that isn't constrained by gravity so you can go wild and do what you like. It doesn't appear to be necessary at the 300m size. It mostly seems to be important for really, really massive structures such as the [X-Seed 4000](https://en.wikipedia.org/wiki/X-Seed_4000), a 4000m tall steel construction that would have had to deal with some quite serious environmental challenges that more sensible sized structures don't have to worry about.
I shall point out though that there's nothing about steel that has an intrinsically bad carbon footprint. It can be refined and (re)formed using nuclear or renewable electricity sources and there's obviously quite a lot of it about in existing buildings that can be recycled at some point in the future when those buildings come to the end of their useful life. Composite steel and wood buildings might not tick the bio-eco box, but there's no reason to think they'd be bad.
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The tallest mostly wooden structure ever built in pre modern times was probably the legendary Yongning Pagoda at Luoyang, capital of the Northern Wei dynasty in northern China.
The Yongning Pagoda was described in *Record of the Buddhist Monasteries in Loyang* to be 90 Zhang high and 100 Zhang with the spire, or 330 meters (1082.68 feet), but in the commentary of the *Waterways Classic* "only" 49 Zhang or 163 meters (534.777 feet). Archaeologist Yang Honxun who excavated its foundations believed it was about 147 meters (482.283 feet) tall.
See discussion at: <https://historum.com/threads/why-do-ancient-chinese-architecture-hardly-ever-go-up.46370/page-9>[1](https://historum.com/threads/why-do-ancient-chinese-architecture-hardly-ever-go-up.46370/page-9), page 9, posts 88 and 89.
Note that the Great pyramid is 138.8 meters (455.38 feet) tall and was 146.5 meters (480.643 feet) tall when completed. The facing stones were loosened in an earthquake in 1305 and later carried away, and the pyramidion at the top is missing.
So it is possible, though not certain, that the Yongning Pagoda was taller than the Great Pyramid for a few decades.
It was completed in AD 516 and caught fire in 534, allegedly burning for months. Thus there is little evidence whether it could have stood for centuries or would have soon collapsed.
The tallest Pagoda built in modern times seems to be the pagoda at the Tianning Temple in Changzhou built from 2002 to 2007, which is 153.79 meters or 505 feet tall. But it does have a steel support structure so that doesn't count, I guess.
<https://en.wikipedia.org/wiki/Tianning_Temple_(Changzhou)>[2](https://en.wikipedia.org/wiki/Tianning_Temple_(Changzhou))
Renan's answer states that the giant hanger at the Tillmanhook Air Museum, Tillmanhook, Oregon is 326 meters or 1,072 feet tall. However, that is the length and not the height of the hanger:
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> Constructed by the US Navy in 1942 during World War II for Naval Air Station Tillamook, the hangar building housing the aircraft is 1,072 feet (327 m) long and 296 feet (90 m) wide, giving it over 7 acres (2.8 ha) of area. It stands at 192 feet (59 m) tall. The doors weigh 30 short tons (27 t) each and are 120 feet (37 m) tall. Hangar "B" is one of two that were built on the site originally, Hangar "A" was destroyed by fire in August,1992.[2](https://en.wikipedia.org/wiki/Tillamook_Air_Museum)
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<https://en.wikipedia.org/wiki/Tillamook_Air_Museum>[3](https://en.wikipedia.org/wiki/Tillamook_Air_Museum)
The much lower actual height of 59 meters or 192 feet is still impressive.
The hanger has lasted for about 78 years since 1942 and it could last for centuries if it never catches fire like its twin did.
The Gliwice Radio Tower in Poland is the tallest existing wooden structure, 118 meters or 387 feet tall, built in 1934.
<https://en.wikipedia.org/wiki/Gliwice_Radio_Tower>[4](https://en.wikipedia.org/wiki/Gliwice_Radio_Tower)
<https://en.wikipedia.org/wiki/List_of_tallest_wooden_buildings>[5](https://en.wikipedia.org/wiki/List_of_tallest_wooden_buildings)
The *Mjostarnet* in Brumunddal, Norway, is the tallest wooden building in the world at 85.4 meters or 280.1837 feet tall, completed in 2019.
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> Mjøstårnet by Voll Arkitekter in Brumunddal, Norway, has been verified as the world's tallest timber building by the Council on Tall Buildings and Urban Habitat.
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> The 85.4-metre-high tower was built using cross-laminated timber (CLT), a pioneering material that allows architects to build tall buildings from sustainable wood.
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> It has taken the title of world's tallest timber building from the 53-metre-high Brock Commons Tallwood House in Vancouver, which has a hybrid wood and concrete structure. Treet in Bergen, Norway, which is 49 metres high, used to be the tallest all timber building until Mjøstårnet completed in March 2019.
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<https://www.dezeen.com/2019/03/19/mjostarne-worlds-tallest-timber-tower-voll-arkitekter-norway/>[6](https://www.dezeen.com/2019/03/19/mjostarne-worlds-tallest-timber-tower-voll-arkitekter-norway/)
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[Question]
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The animal I'm particularly focusing on is a cat, for which I'm curious how long it would take for said cat to evolve into a bipedal, intelligent, humanoid being capable of complex language and all other things that an intelligent species can do, if it's even possible.
The world that my story takes place in is where global warming and climate change aren't necessarily something to worry about, and the planet has plenty of time to change.
The cats are mainly domestic, and a lot of them had owners before all humans left the planet to travel space. After that, they all became wild for however long it takes for them to evolve into humanoid creatures and take over the planet.
I'm not sure if continental drift will affect anything, because again, I'm not sure how long this evolution will take.
So how long would it take? Is it even possible for the cats to evolve, or is it something about their species that prevents it?
If there's anything I need to add to this to make it more clear, let me know.
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**100,000 years (or 100,000 generations), give or take, assuming ideal conditions**
So, let's get the math out of the way first; the first animals of the human genus appeared on earth [around 2.5 million years ago](https://en.wikipedia.org/wiki/Timeline_of_human_evolution#Timeline_of_Homo_sapiens). Assuming that we are relatively new on the scene, and we are estimated to have first appeared around 100,000 years ago, that would mean that it has taken us around 2.4 million years to evolve from our first ancestors. If we make the math easy on ourselves and assume that a human 'generation' is 24 years, that means that we evolved in 100,000 generations. That assumes of course that the early homonids were almost cat-like in their levels of intelligence and interaction with the environment, which is a large assumption to make.
Cats are capable of gestation within 6 months, but (again to make the math easy) let's assume that the average feline generation is 1 year - if so, and if it takes the same number of generations to achieve humanoid intelligence and traits, we're looking at around 100k years for it to happen.
There are some **massive** gotchas in that estimate though. First, cats can live for 10 to 20x past their first batch of the next generation, and they remain fertile for a lot of that. There would be a massive cross-fertilisation of 'generations' as a result meaning that cats would be unlikely to have generational progression on the same rate as humans.
Additionally, humans have very few children by comparison, live for only around 3x their age at their first generational production and are fertile for a lot less than that. This is important because it means that there is not as much cross-fertilisation across the generations but even more importantly, less competition for resources between generations. Cats are going to live for some time, constantly cranking out offspring, meaning that there is a high chance of a population blowout that could wipe out the species through stripping of all resources if a given generation proves sufficiently prolific.
Also, cats are already well adapted to their function as hunters, there are few threats that would evolutionarily reward the high expenditure of energy in neural enhancement like what humans were adapting to. Cats are already 'intelligent enough' for what they do and it would take a very specific set of circumstances to make intelligence more important than their existing traits in hunting.
What is far more likely is that cats will run out of food and begin to compete with each other if their numbers increase in an uncontested environment. Intelligence may be a desireable trait that is rewarded with survival in such a case, but it is rare enough that I doubt it. That said, cats would have a far better chance of developing intelligence if they had fewer offspring as it would mean that the previous generation can't overwhelm the next one with numbers that make intelligence irrelevant as a survival trait.
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It's highly unlikely that a highly specialized form like a feline develops into another highly specialized form like a humanoid. Too much rebuild to be practical.
Evolution usually works better starting from a general purpose form and ending up in a specialized one, as it is easier to select the advantageous traits.
If a feline is specialized in hunting, losing any of the related character (i.e. the claws) in the transition to humanoid would be disadvantageous and would lead to a dead end.
[Answer]
There are theories that human intelligence evolved at least in part due to the demands of caring for helpless offspring. Certainly in mammals and birds we tend to see that the brains of [altricial](https://en.wikipedia.org/wiki/Altriciality) species grow larger beyond infancy whereas those of precocial species do not develop hugely beyond infancy. Thus altricial species tend to end up more intelligent than precocial ones. The good news for you is that cats, like humans, are altricial (though not as strongly as humans).
What follows is speculation.
You need some kind of constraint to trigger evolution. Perhaps in your post-human world resources for cats become scarce, or they start to be out-competed. That's a plot detail. Those cats that are cleverer start to do better in terms of obtaining the resources. Suppose the mechanism by which a cat ends up cleverer is linked to its altriciality. Thus cats become more and more altricial, more and more clever, to deal with the resource constraint. At the same time, and maybe for related reasons, cats with more pronounced spur claws are favoured, and in time the dewclaw develops into a thumb-like digit allowing tool use. Some cats are already social animals living in prides or colonies, so again your evolutionary stimulus could encourage greater social reliance, ultimately resulting in more expressive / abstract language. All of the features above could mutually reinforce, providing a positive feedback favouring greater and greater intelligence. For added credibility though, don't expect that they would look highly similar to humanoid. Cats can already sit on their haunches to do things with their front legs (bat at Christmas tree baubles, for example) so perhaps they would just do this to use tools rather than fully standing upright, and maintain a four legged gait. Cat digestion is much more specialised to carnivorousness than human digestion is, so they are perhaps less likely to lose features related to carnivore specialisation (so they probably retain their clawed digits even if those digits become a bit more versatile, and they aren't likely to suddenly become arable farmers, though perhaps they might farm prey animals).
The timescale probably depends on how harsh the evolutionary incentive is: a mild incentive will result in a longer time to evolve or simply other factors driving evolution in a different direction. Too harsh an incentive and the species dies out without being able to evolve. Get it just right and you get your intelligent cats. To an order of magnitude 10 million years seems plausible, maybe longer, maybe a bit less.
Most likely it would never happen at all - human level intelligence has only evolved once so far out of millions and millions of species - but as author you do get to use the anthropic principle (felinthropic principle?) "I can justify that it could theoretically happen, therefore I choose to set my story in the universe where it did happen."
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They would probably never evolve into humanlikes, no matter how much time you give them.
Cats are predators, they don't need bigger brains to survive better. They are not even pack animals - yes, that is important.
For humans bigger brains were an immediate advantage, because it allowed better cooperation. It was not the skill to craft some spear that led to survival, it was the ability to hunt in packs, cooperating, that ensured a steady surplus of food. The ability to remember and identify a bigger variety of edible fruits to collect.
For cats that is no route to go. They hunt alone, they are not social and they only eat what they hunt.
You have way better chances with apes or even wolves than with cats.
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A demigod is a mortal being infused with divine energy. This essence comes from a divine spark in their soul that activates due to some external traumatic event. The demigods ascend to the higher plane to join the true gods in their fight against demons, and occasionally return to the mortal realm for some dire reason, like an invasion.
The religous organization of the world has "chirches" in all corners of the world and operates out of a small city-state, where bodies of great heroes are interred in the maseoleum as a final honor. They are responsible for maintaining the faith and supporting the demigods on earth. On the rare occasion that a demi-god dies on the mortal world, their soul departs to the afterlife. However, their bodies remain, incapable of rotting and staying in prime condition. People would be come together around these locations, sacralizing it. These groups would be similar to the ancient cults of greece. Each dead god would have its own cult of caretakers. They would build a monument to protect the body and guard it day and night.
However, these cults are not affiliated with the main organization in any way, having originally just been from random people who volunteer to come together on this common cause. Rather than collecting the body, the organization allows them to continue. I could see a fee issues with this. The org. Is potentially encouraging a future rival, threatening their power and influence with the people. Branch organizations could sprout from these cults, breaking the faith into sects.
How could the organization allow these cults stay in possession of these bodies instead of maintaining them all themselves?
[Answer]
Actually, the Catholic church does something like this. Each of the various religious orders — e.g., the Jesuits, the Franciscans, the Carmelites, the Benedictines — is to an extent a law and community unto itself, approved of and authorized by the pope. The Vatican bureaucracy is actually a hotbed of political infighting between various orders, and many orders have (over time) maintained their own relics (body parts of various saints) which are presumed to have certain religious powers.
In a universe with actual demigods, I imagine that various orders would spring up around each demigod, and that each order would maintain the physical body of its namesake (and any associated quasi-divinities) for both symbolic and practical purposes (practical meaning any working powers that the remains could provide, such as healings, blessings, visions...). These orders would then be incorporated into the doctrine and hierarchy for an established and overarching religion: the overarching religion would gain/maintain followers and avoid creating schisms; the new order would gain legitimacy and while sacrificing certain elements of autonomy. win win...
Think of it in feudal terms, where a ruler must cede *some* authority to subordinate aristocracies in order to maintain the cohesiveness of the group at large.
[Answer]
**Your fictional world has direct proof that an afterlife exists**
A religious organization in a reality that has an actual demonstrably real afterlife has no burden to compete for power with other religious organizations. All these sects taking care of the bodies of these demigods pose no threat to them. They are, after all, glorifying the main religion's position on how things work. Allowing them to venerate their heroes has no negative effect on them. In fact, encouraging this behavior just makes themselves and their position on the afterlife stronger.
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It seems to me that the easiest way to force a culture or organization to come together is to give them a common enemy. If these offshoots were officially seen as evil or somehow demonized, the leaders might unofficially allow the offshoots to crop up to give the main populace something to abhor and promote more zealous followers of the mainstream.
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Here is Carolina Lang's interpretation of one of Britain's heraldic beasts, the enfield:
[](https://i.stack.imgur.com/rD2kU.jpg)
For anyone not familiar with the creature, here's A Book of Creatures' basic description of it:
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So in the long and short of it, a very interesting species of canid--wait, hold up. EAGLE talons? Clearly, some foreign author doesn't know how else to describe this newly discovered creature's footwork.
So disregarding the "mad scientist stitching bird feet onto a dog's body" handwavium, how and why would the enfield, if it were a real wild animal, have long, sharp claws, something that other canids don't have?
[Answer]
The [racoon](https://en.wikipedia.org/wiki/Raccoon) has paws which are way more articulated than those of a canid
[](https://i.stack.imgur.com/7dK1K.jpg)
This is a consequence of the well developed manipulative skills of the animal itself.
If whoever observed the enfield in the wild was not exactly in their senses, maybe because they had too much grog to keep them warm in the mists of the moorland, they can easily confuse such a paw with an eagle one.
[Answer]
**The Enfield is a felid.**
The problem with eagle claws on a canid is that eagle claws are sharp, for catching fish, and canids run on their claws, blunting them to stubs. Felids have worked around this by making their claws retractile. Cats (except cheetahs) run on their pads to save claw sharpness, leaving claws ready for use as weapons. One could make a case that this evolutionary coup makes felids superior predators as compared to others in their order. The sharp hooked claws of the [fishing cat](https://en.wikipedia.org/wiki/Fishing_cat) compare to those of the eagle. Cut the cat some slack, now - it has to be able to retract those claws back into the paw.
[](https://i.stack.imgur.com/LuJK5.jpg)
<https://wildcatconservation.org/international-conservationists-develop-conservation-strategy-plan-fishing-cat/fishing-cat-claws/>
The Enfield takes this one step further; one might assume that like eagles and fishing cats, the Enfield eats a lot of fish. Its paws are bigger and its claws are longer, sharper and more curved.
As regards the wolf tail, I assert that a little bit of evolution could easily give a felid a wolf tail. Felids have a wider range of tail shapes than canids including stubs, long tentacles, fabulous fluffy boas (the snow leopard) and this charming kitty who is no doubt proud of her vulpine tail.
[](https://i.stack.imgur.com/IYabR.jpg)
<https://pixy.org/272564/>
[Answer]
**It climbs trees**
If it hunts birds or other tree dwelling prey, long claws are a must to get up and down trees. Not so much bird feet but cat like claws
[Answer]
The trouble with the talons of an eagle is they're not designed for running with the speed of a greyhound. They also clash with the canid hunting style which goes in face first rather than the eagle style of talons first. The body of a lion is that of an ambush predator, the hind legs of a wolf are those of an endurance runner.
Ability to grasp, bite, and we'll call the combined back end a long attack spring.
The best path is possibly over specialisation on a particular form of small to medium highly evasive prey. This prey requires both grasping claws and teeth to be able to catch and kill it. Perhaps this is a creature that hunts in shallow water for octopuses or similar slightly dangerous prey.
Maybe a mangrove specialist, where the ability to hang onto branches while waiting for the spring to attack finds the balance between the claws and teeth, though there'd be an argument for either rear talons or front and rear talons in that option.
[Answer]
It runs very fast. The Ostrich has long claws, adapted for running, so I guess the Enfield's claws are long because it chases very fast-running prey.
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Let us assume that in the next 50 years one of the large nation-states of our world will build nuclear powered planes, for intercontinental flight. Supposedly, the nuclear planes would be bigger, faster, and need less oil in a world where good oil sources are dissapearing (so, assume that peak oil is true and that by 2070 the peak has come and gone). Also, nuclear planes would be a stepping stone to regular suborbital space planes, then to LEO space planes, that would be used to build nuclear pulse propulsion ship (AKA, orion bomb drive). The nation-states have deep pockets and are commited to develop the nuclear planes. We can, if necessary, assume that the nation-state in question can ignore public opinion for a long time, maybe it's a dictatorship like Soviet Union was and can ignore international outrage if something goes wrong.
Having said that, the government does not want a Chernobyl in the sky and would like for the nuclear plane to be as safe as possible. One of the main dangers of such a plane is the radiation emitted by the reactor: that will hurt the crew, irradiate the cargo and damage the control systems. How can the designers contain the radiation without using massive shielding like that used in well-built nuclear power plants? My first idea was to use a tungsten carbide sphere around the reactor to reflect the neutrons back to the fissile material and be able to achieve sustainable fission with less material while at the same time getting rid of the dangerous hot neutrons. I am aware that T.Carbide is heavy but is better then the meters of concrete and lead nuclear power plants use.
The nation-state is ignoring the other danger of the nuclear plane - it crashing and irradiating neighborhoods, there isn't much that can be done about that except placing the airports and the routes far from the cities and critical farmlands.
Would that work? If it won't, why, and what would work?
[Answer]
Short answer:
## If it would work, someone would have done it already
As was pointed out in the comments, this *was* explored in the 1950s and 60s, and an [airborne nuclear reactor](https://en.wikipedia.org/wiki/Convair_NB-36H) was built and run. The insurmountable problem (as you cover in the question) was that shielding a nuclear reactor requires heavy materials. This is a property of radiation, and is unavoidable.
The whole purpose of the NB-36H was to determine if sufficient shielding to protect the crew and cargo could be provided while still allowing the plane to fly under the power of the reactor. Not only was this not the case, but the heat exchanger used to heat the air for the jet engines (not used in the NB-36H, but in ground testing) mildly irradiated the jetwash, which would probably be unacceptable to flyover countries.
It's possible that [metamaterials](https://news.ncsu.edu/2015/07/rabiei-foam-rays-2015/) might be useful in constructing lightweight radiation shields:
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> Research from North Carolina State University shows that lightweight composite metal foams are effective at blocking X-rays, gamma rays and neutron radiation, and are capable of absorbing the energy of high impact collisions. The finding means the metal foams hold promise for use in nuclear safety, space exploration and medical technology applications.
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Even then, the issue of channeling the heat to the jet engines potentially circumvents this protection, because any heat exchanger is necessarily going to be exposed to the reactor core, and its medium will become irradiated.
Your best near-future hope may be to wait for cheap, practical fusion, and build a *truly colossal* aircraft. The neutron flux per unit power from a fusion reactor is much lower than a fission reactor, so your energy density is higher per unit mass. But fission is almost certainly a non-starter. The nuclear-crazy 50s and 60s gave us all the information we need to conclude that.
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Edit: Another comment mentioned the nuclear ramjet engine. [Project Pluto](https://en.wikipedia.org/wiki/Project_Pluto) definitely *would* work, with the right materials, but the quantity of radiation and fallout expelled from the engine would make it *totally* unacceptable for any use but the one for which it was envisioned - a loitering cruise missile meant as a nuclear deterrent.
[Answer]
The US and the USSR both [extensively researched](https://en.wikipedia.org/wiki/Aircraft_Nuclear_Propulsion) nuclear powered aircraft in the past.
As traditionally designed, these aircraft wouldn't be a bridge to space planes, since they still need air to function. Radically different technology would be required to get to space. [Nuclear rocket](https://en.wikipedia.org/wiki/Nuclear_thermal_rocket) technology could get to space, and has also been tested. In general, such technology wouldn't be reasonable to use for flights inside the atmosphere. Air breathing engines are simply far more efficient. However, it would be possible to build an engine that could convert from using a nuclear reactor to heat an onboard propellant, rather than air, and bridge from atmospheric to orbital flight.
The primary downsides of traditional designs for space planes have been the issues of crew shielding and crashes, neither of which were ever resolved, and neither of which have any real means of resolution based on modern technology. Shielding is heavy, and there's no way to stop a reactor hitting the Earth at supersonic speeds from being a mini-Chernobyl. Nuclear rockets, furthermore, tend to irradiate their exhaust. The only ways around these issues are to not have people on board, and to not care about nuclear pollution. Those are certainly possible, but mean that fission-powered nuclear aircraft won't ever really be a viable replacement for all the things we currently use fuel-burning aircraft for.
As such, any reasonable nuclear powered flight will have to rely on fusion, rather than fission. Electric engines would be reasonable for atmospheric aircraft, and it's likely that it would be possible to build a thermal engine, as well. Current direct-thrust [research](https://en.wikipedia.org/wiki/Direct_Fusion_Drive) leans towards high specific impulse low thrust engines, which likely makes it unsuitable for any atmospheric flight. Fusion, compared to fission, creates relatively little radiation, and no mini-Chernobyls when aircraft inevitably crash. However, we have yet to realize any net energy production through fusion power. In order to produce a reasonable aircraft in 50 years, we'd need some major breakthrough to happen in the near future, as substantial refinement and miniaturization of a fusion power source would need to happen before it was reasonable to put one on an aircraft.
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As multiple people have stated, the americans (and probably russians) did experiment with atomic airplanes in 50-60ies. Though to elaborate a bit on this, the primary reason nothing came of it, was not due because it couldn't be done. Because of weight limitations in airplanes they were working on whats called a MSR (Molten Salt Reactor) that has a number of advantages over a regular reactor as we know it. It's safer, it's inherently stable and can't run out of control and it's potentially much lighter/smaller.
More data here: <https://en.wikipedia.org/wiki/Molten_salt_reactor>
The last hurdle that was not solved before funding was cut (for other reasons), was removing the nuclear waste from the salt solution. Due to lack of funding and the unpopularity of nuclear energy further research was sadly not done. (some work has been done from private sector, though mostly theoretical as far as i know)
[Answer]
**Fusion plane.**
All of those fission-reaction powered planes were covered in other answers. That is totally doable and not really science fiction. Probably a fission rocket is what the [Russians were bragging about recently](https://www.wired.co.uk/article/russia-explosion-nuclear-rocket-physics). Fission power uses the heat generation by the breakdown of heavy elements and in the process liberates additional radioactive materials - fission products. Fission is what we use now for nuclear power, and all the nuclear weapons have some fission component.
But you are in the future. In the future we will have figured out [fusion power](https://en.wikipedia.org/wiki/Fusion_power). Fusion power does not generate radioactive fission products or gamma rays. It just generates loads of heat and that is what you want. Your fusion engine heats the air and throws it out the back, just like a ramjet or one of these fission rockets.
The reason fusion power is not being used now is that it is hard to compress the starting materials enough to get it started. Hydrogen bombs use a fission explosion to achieve that compression. Without that you need giant lasers or other things not amenable to mounting on a plane. But maybe muons or some other tech will facilitate fusion in the future such that you don't need a Tokumak.
Fusion power is near future science fiction and using this form of energy to power a plane is totally plausible science fiction.
[Answer]
You can easily stop alpha radiation, beta isn't that difficult, while gamma is nearly impossible to stop. So, you require something that emits (mostly) alpha radiation.
Your probably best candidate would be Po 210 (<https://en.wikipedia.org/wiki/Polonium-210>). It takes about 4 months to decay, while product is stable lead. Getting enough of material is a pain you have to solve yourself, likely just by scaling up existing operation - Russia exports several grams per month to US.
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My world is in a modern setting but populated with a variety of fantasy/mythology races and creatures.
I am trying to figure out how each species would best be utilized in a modern military, assuming he has human intelligence and is willing to serve.
The obvious pros of centaurs are that they can carry a lot of weight without being slowed down, and generally their high speed. On the other hand, they are a very large target and they have trouble maneuvering tight spaces. I am thinking they would mostly be used for logistics (i.e running with supplies from safe bases to the front line).
Could Centaurs be used in actual combat? Would they have any role at all in the military?
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> Would they have any role at all in the military?
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All their advantages are basically physical ones of little use in normal combat situations, so I think their best use would be as military police. They have the size, strength, speed, intimidation potential and stamina to deal with military personnel in many scenarios.
A good alternative would be as paramedics, they can carry wounded soldiers faster, easier and more often even if wearing heavy armour against bullets.
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Sure, little kids, old people, cripples and the insane have all been used in combat, but due to equipment and other factors they're all less desirable than able bodied adults.
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Assuming that they would be fine in forested or mountainous terrain?
I'd see a role for them not in front line units, but in **logistic support, but only in harsh terrain**. They are too big for being front line soldiers. However, in situation when something has to be carried (dragged) in terrain not suitable for terrain cars, they would outclass any human being.
[Answer]
Horses have no longer practical usage in modern armies, because motorized vehicles are more effective within the modern context of large scale warfare.
The same can apply to your centaurs.
The only niche where they can prove useful is small tactical infiltration support, where they can serve as advanced beasts of burden: they carry loads, but with the human torso can also use a weapon if needed, while a horse or a mule would simply take shots.
[Answer]
Back in the day, Boston Dynamics made a slightly silly robot called "Big Dog" which received some DARPA funding. Also named the "Legged Squad Support System", it was intended to be able to walk alongside infantry across rough terrain and along narrow paths, carrying up to 150kg of gear which would obviously be good news for soldiers who might have to carry 20-40kg of equipment with them and even then compromises would have to be made.
[](https://i.stack.imgur.com/ukYLT.jpg)
The robot [ultimately failed](https://arstechnica.com/information-technology/2015/12/us-militarys-ls3-robotic-mule-deemed-too-loud-for-real-world-combat/), not because it was a silly idea but because it was noisy as hell. By comparison, horses can move extremely quietly when required, so your military centaurs would immediately fit into this niche, fulfilling a requirement which would appear to be something that real world militaries actually care about.
They'd be less useful as actual soldiers though... they present a bigger target than a person (making them easier to shoot and harder to hide), they're not as manoeverable as a person (think about how a horse is going to do a 180 in a narrow space) and they can't easily make use of things like ropes, ladders or inconvenient staircases to access higher or lower areas. They can't operate vehicles without serious modification, they'd be a right pain to transport by air or by small boats.
Parachuting of mules [is a thing](https://www.fold3.com/page/642791606-using-mules-in-burma) that *has* happened in the past (there's an intrguing paper I can't find the full text of called [Dropping of mules by parachute from Dakota aircraft](https://www.ncbi.nlm.nih.gov/pubmed/20988137)) and as many as [1300 mules were flown into Burma](https://www.deepdyve.com/lp/elsevier/burma-s-long-eared-paratroops-ADy1crcSnW), though alarming phrases like "*the jerk of the parachute opening could burst their mesentery artery*" suggests that there might not be many centaurs interested in ~~forming a pegasus unit~~ joining the parachute regiment.
Finally, they'd be harder to feed and they'd need a whole additional set of medical skills and equipment in order to keep alive and well, presenting something of a logistical nightmare. There's not much in their favour outside of some pretty specialist roles.
I'd say their usefulness would have ended at some point before WW1... probably pre-Boer War, ~1900 (when British cavalry stopped using lances), but might have still been useful and relevant into the mid-to-late 1800s.
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There are some roles where a centaur's large size and high profile make it a liability - front line infantry, tunnel clearing, flying manned aircraft - but most of these are becoming marginal for humans as technology advances. To give a few thoughts on where centaurs would be equal or superior to humans based on my own experiences in a light infantry battalion:
* light infantry mortar platoon. Western armies have learnt the hard way in various conflicts over the last few decades that air support is frequently an inferior substitute for a friendly mortar baseplate (aircraft cannot stay on station indefinitely, if they get shot down then you lose that aircraft *and* all the resources needed to rescue the crew). However, inserting a mortar platoon to right where you need it in rough terrain can be problematic - there are often situations where ground vehicles or aircraft cannot access the area or will be observed and compromise the operation (think Afghanistan's mountains). A surefooted centaur mortar platoon can insert with its tubes and enough ammunition pretty much anywhere a human special forces or infantry element needs it.
* drone close support element - similar to a mortar platoon, centaurs can lug in some large-ish drones and their ordnance to a LZ within a minute's flight of where a human advance element is operating. While centaurs are suboptimal as pilots of manned combat aircraft due to their size (and possible susceptibility to high G forces), there is no reason they cannot pilot drones as well as the next man.
* field engineers - front line engineering units are always operating with minimal equipment in my experience, there is generally no plant available (eg bulldozers, backhoes) and so most tasks need to be carried out using hand tools combined with human muscle power and mechanisms that Archimedes would recognise. A mixed human-centaur assault pioneer / field engineer unit would have huge advantages - the humans would still get to crawl though minefields and work on the inside of human-size bunkers, but when the serious digging jobs need to be done the centaurs can operate really impressive jackhammers, pound star piquets into the ground with serious weight behind them, run barbed wire out much faster than humans etc.
* signals units - deploying line, setting up retransmission positions - centaurs can do most of it faster than humans and can operate the equipment without their size being a disadvantage.
One last thought - some answers and comments have focused on centaurs' inability to take cover effectively like a human infantryman. Given that most casualties in war are not caused by small arms fire but instead are from indirect fire / airstrikes, IEDs, disease and other causes, this my not be a critical consideration.
[Answer]
# Drone operators
Let's face it. Centaurs may run fast on a straight line in the open field but that's it for their advantages.
They are bigger targets, will have a horrible time busting into urban enemy positions, and can't pilot ant vehicle made for humans.
The only place where they won't be causing problems is bebind a desk. If they are to do damage, give them some RC toys.
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If you have ever read the book Leviathan or the rest of the series, they have a series of genetically engineers animals that are used as weapons platforms. A centaur could theoretically become a very heavily armored soldier due to their enhanced stamina and carrying capacity.
An M249 SAW could be a good weapon for a centaur. It could be mounted on the flanks of the horse section, and remotely fired from the human section. It would, of course, be slightly extended from the body because of heat and other reasons. This sort of unit would be rather expensive because of the cost to fully armor and equip it. An M249 has a manufacturing price of 4,807 USD. And the cost to armor it would be even more.
Another idea is a rider that could mount the centaur. (we are assuming the centaur permits it) The rider would serve to reload the mounted guns and provide covering fire in all directions. A horse can carry up to around 25 percent of its body weight in cargo. We are going to say the weight of this centaur is going to be the sum of its horse body and its human torso. I am going to take the liberty of saying that this particular centaur's horse section is around 1,500 pounds. The average human torso and head are about 113.1 pounds. So this means this centaur would be able to carry about 403 pounds. A full human male in combat gear is about 250. Two fully loaded M249s would be 44 pounds. Added ammunition would be about 40 pounds. So all in all this would work.
So these troops could not be simple front line soldiers, they are too expensive. I believe they would suit a more shock trooper role. I see it as a modern equivalent to the war elephants used by Alexander the Great. I hope this helped!
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For some reason, all the nations in the world have banded together. Their goal? Go to the Moon. Their budget? As much as the planet and humans can throw at it.
How fast could we build a reliable and safe (think the reliability and safety standards of NASA missions), 3 people manned return mission to the Moon? [Assume we don't have any spare rockets / parts just lying around.] The astronauts will land on the moon and stay on the moon for about 24 hours.
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## It depends entirely on how desperate the need is
Or rather, what likelihood of failure the organisers are willing to accept.
We already have a design for a machine that can take three people to the moon, allow them to stay there for 24 hours and return. We went from zero to first launch of the Saturn V in [about 5 years](https://howthingsfly.si.edu/ask-an-explainer/how-long-did-it-take-build-saturn-v-rocket). And the plans still exist, and are even public domain. By far the simplest way to get back to the moon is to take them off the shelf, knock off the dust and start building.
Except that that's crazy, because that technology is *old*, and that's a problem for two reasons. Firstly the supply chains (indeed the entire industries) that support the availability of the component parts are gone and would also need to be rebuilt, an exponentially expanding logistical challenge. And secondly, the capabilities of the equipment are, by modern standards, *horrifically limited and unsafe*. The Saturn V autopilot, for instance, was a computer with a clock speed of 2.048MHz and a processing capability of *12 kiloflops*. That's less powerful than an Arduino. The main computer of the Apollo command module was the size of a suitcase (and would incur excess baggage charges by most airlines) and not significantly more powerful. Components were huge, weighty, very limited in their functionality and would be *oh so easy* to replace with modern components which would be much easier to manufacture with modern supply chains and far more feature-full.
Assuming that they work correctly. Assuming that replacing a 30kg lump of metal with a single featherweight integrated circuit won't skew the centre of gravity of the ship in an unexpected way. Assuming that swapping in 3D-printed titanium or carbon fibre instead of milled lithium or whatever else they used doesn't have some unexpected effect. Assuming that whatever interface they introduce to interface 32- or 64-bit modern electronics to the 14- or 15-bit original electronics doesn't have any unexpected bugs. And so on and so forth.
You can iron out all these bugs with testing, the more extensive (and lengthy) the better. The longer a timeframe you allow, the more stuff would get swapped out for modern components until, Thesean Ship style, you'd end up with a design using mostly modern parts.
More realistically, engineers now probably wouldn't start from Apollo, but from more modern rocket programs, but the principle is the same: you can rush something out and have an exponentially increasing chance of mission failure, or you can go slower and steadier, and be progressively more certain of being able to do the mission successfully and safely.
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The main time-eaters on such a projects are tests and reconnaissance mission. So the answer depends on required reliability.
1) If we can "afford" to loose mission or two - than it would take about the same as Apollo program - about 5 years for first landing (Apollo nearly lost one mission and there were deaths on tests). But by post-coldwar standards this is too risky. Apollo mission was held at fastest rate possible, not by money, but by R&D and production. Modern computers would reduce risks, but not time: R&D is about people communication and thinking - and this can't be accelerated much.
2) If we want to send people on the Moon reliably, we would need a lot of preparations, Earth-based and Moon-based tests (like first lander will test-land without people and will be a backup if manned lander would malfunction, and etc.). So it would be about 10-15 years from start to landing.
3) If you need to land "at all costs" - you will need about 6 month to couple of years. It would be a strange mission: slightly modified Russian Soyuz (which was made from an actual moon-lander) on top on Falcon Heavy rocket with some custom intermediate stage (to brake at moon orbit and accelerate back). But I would bet 300 dollars against 100 that this mission would fail.
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If all the nations in the world banded together and formed a public-sector agency to consider the best way to define and implement this goal, and if every person on Earth contributed to the project to the best of his ability, it would probably take about nine years from commitment to safe return.
If all the nations in the world banded together and formed a superfund and hired Elon Musk and then left him alone to get on with it, it would probably take about two years. It would be profitable in nine.
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A town dating back to the late 1880s in northern Wisconsin has a dark secret that must be kept hidden by as few people as possible. How can this town keep itself isolated and off of maps during the time period while maintaining a relative population of 5,000? How does it accomplish this through the 20th century?
By the way, the town exists until 2003 or so, long before Google Maps was a thing, so don't involve digital age technology too much. And the government isn't involved in this secrecy.
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Ever heard of [Monowi, Nebraska](https://en.wikipedia.org/wiki/Monowi,_Nebraska)? It has a population of one.
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> Monowi was [**platted**](https://en.wikipedia.org/wiki/Plat) in 1902, when the Fremont, Elkhorn and Missouri Valley **Railroad was extended** to that point. **A post office was established** in Monowi in 1902 and remained in operation until 1967.
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> Monowi's peak years were in the 1930s, when it had a population of 150. Like many other small communities in the Great Plains, it lost its younger residents to cities that were experiencing growth and offering better jobs. During the 2000 census, the village had a total population of two; only one married couple, Rudy and Elsie Eiler, lived there. Rudy died in 2004, leaving his wife as the only remaining resident. In this capacity, she acts as mayor, granting herself a liquor license and paying taxes to herself. **She is required to produce a municipal road plan every year** in order to secure **state funding for the village's four street lights**.
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All emphasis are mine.
So, if you live in undesirable land, live off the grid, don't plat the place, make no municipal road plan and keep population to a minimum, you might just be able to pull it off.
About 5.08% of Wisconsin's area is federal land, mostly in the North. You might be able to evade scrutiny from the State of Wisconsin as long as you hide in there, but then you have to hide from Uncle Sam himself. Depending on where his focus in on the moment it might be easier or harder to hide. So you might wish to stick to places close to the border of federal and state lands and live nomadically.
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Why do you need to stay off the maps? Just craft a reputation as an insular enclave of religious fanatics, like Bountiful BC but even more so. (See <https://en.m.wikipedia.org/wiki/Fundamentalist_Church_of_Jesus_Christ_of_Latter-Day_Saints> ) for more info.
The community keeps to itself, with only a few highly trusted people making trips to town to trade for anything that can't be made at home. (Be progressive -- your insular Luddites can still buy vaccines and computers to manage the dairy herd.)
You keep the dark secret by cutting all the communication channels.
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It can't.
Two things: first, where is it getting supplies from? Northern Wisconsin has this thing called "winter" and that means burning some kind of fuel, and that leaves evidence, whether it's clearcutting forest or someone buying fuel and transporting it. A community of 5000 people is no small thing when it comes to this subject. Also, water. Several thousand people are not going to live off a small, unnoticed spring. They'll need a river or lake, and waterbodies attract people.
Second, you can buy antique maps dating from the 1850s on showing the mapping going on in Wisconsin. By the 1890s you have US Geological Survey maps being produced. By 1900 and earlier, detailed topographic maps of the state. Between 1937 and 1941, the U.S. Department of Agriculture and U.S. Geological Survey carried out aerial photography of the entire state, which you can see online here:
<https://maps.sco.wisc.edu/WHAIFinder/#10/45.1907/-90.0453>
You'll note complete coverage of the entire state at sufficient scale that a community of a hundred people would stand out, let alone a community of 5000. It would be essentially impossible to hide a single small family farm. Look at those images and you can pick out individual structures as small as sheds.
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Northern Wisconsin is largely forested, going by Google Maps. In such an environment, it should be possible to excavate subterranean dwellings, perhaps by expanding naturally-occurring caves. If the town was located beneath a forested hill entirely within the bounds of one or more parcels of private land owned by people who were privy to the existence of the secret town, this could fulfil the requirement for the town to remain unobserved by outsiders.
However, there are other issues that would arise when any substantial settlement attempts to go unnoticed.
* Any of the population of the town who never interact with the outside world may be legal non-persons in the broader USA. While they would have basic human rights, they might have no documentation, and so would not have the rights of citizens. However, if the town's founders anticipated a time at which the town's secrecy would end, it would be possible for them to have established the town as if it was an unregistered state of the USA which maintains its own records of births, deaths and marriages, with the understanding that there would be a period of considerable legal difficulties upon the event of the town revealing itself and re-joining the USA. However, being on US soil, this secret state's population would automatically be citizens, and given sufficiently detailed genealogies, each living citizen's ancestry could be traced back to documented US citizens prior to the town literally going underground. If the legal apparatus of the town was to be staffed by citizens who had appropriate skills and qualifications gained in the broader US, that would assist the town's possibility to be legitimised at a later date.
* While a large number of people may remain hidden underground, feeding those people would pose a problem. However, I have noted that the town may remain concealed within the boundaries of private property belonging to town citizens who are *also* known citizens of Wisconsin and the USA. If these properties encompass a sufficiently large area of land, it would be possible for these landowners to farm their land and provide the hidden citizens with sufficient food to survive. Alternatively, if these lands were insufficiently large that they could be farmed, the owners could pretend to be survivalists stockpiling resources - and replacing spoiled stored resources - in preparation for the 'inevitable downfall of society', while they are in fact feeding the starving mases hidden below ground.
* The fact that the owners of the land in which the town is hidden must feed the townspeople could place a great financial strain upon them, however, the town need not be without its own resources. Instead of being only farmers, the land-owners may alternatively or additionally claim to be miners, while it would in fact be the townsfolk who actually do the mining. Should the town be sitting within or above a deposit of sufficiently valuable minerals, its output could well be sufficient to entirely fund its continued existence, and could also explain how the town came to be underground in the first place.
* Finally, there are the effects of long-term life below ground to be considered. Lack of sun exposure would lead to a pale, easily-burned complexion and potential vitamin-D deficiencies, however the latter could potentially be offset by a good diet, and the fact that the town is underground and most of its population is unknown to the outside world need not preclude these secret citizens gaining some sun exposure. By rotating the citizens in and out of their underground dwellings, they could be given necessary sun exposure, and not necessarily be noticed by the outside world.
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If person A has had the genes dictating their sight/ the internal structure of their eyes, replaced by say, eagle eyes or cat eyes.
What happens when they reproduce with person B who has regular human genetics?
I would imagine that the genes governing eye structure in cats are incompatible with the genes governing eye structure in humans.
Would the offspring of A and B just not have eyes? Or would their eyes not form properly? Or would they maybe have one set of genes dominate the other and act as a single source of information for the formation of their eyes?
Essentially my question is what happens when two humans/animals that share the majority of their genetics (enough to count as the same species) but have key differences in certain sets of genes mate together?
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There are three generals outcomes given your set of circumstances.
Outcome #1: The genes are incompatible - for whatever reason, the two genes work against each other, maybe they inhibit each other's expression, or they don't synchronize properly. In your case, you wind up with blind offspring.
Outcome #2: One gene is dominant over the other. Normal genetics take over. This is more likely to occur when you're working with altered human genetics than transposed cat genetics. In your scenario, whichever set of genes is dominant (super eyes or normal eyes) gets expressed.
Outcome #3: Co-dominance / Incomplete dominance. These are two different things entirely, either both genes are fully expressed or one gene is partially expressed, resulting in a hybrid. I lumped them together because they result in the same outcome, a hybrid. Such a hybrid, for instance, might be better-than-average eyes, or even better-than-eagle-eyes, somehow. It would *not* be one normal eye and one super eye.
As for what happens in your scenario, the inserted Eagle Eyes DNA would probably clash with human DNA, and the offspring would be blind entirely. Thanks to recombination and crossing over, their children would also keep passing along traces of eagle DNA, and result in a family with eye defects.
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**Somatic mutations are not heritable.**
If you want your gene edits heritable then you will need to edit the germline of the entire organism. Your edited gene parent and normal gene parent will both contribute genes to the offspring and the offspring of the phenotype will depend on dose and dominance of the edited and wild type genes it inherits.
Or a cleaner way would be to produce somatic mutants. Genetically modify only the cells of the eye. The germ cells of your edited organism remain wild type and any children will not be affected by somatic mutations in one of the parents. An example using current tech would be if I get a bone marrow transplant from my sister when I am 11. My blood cells will be female - her blood cells. Over time some of these blood cells might take up residence in various organs. But my sperm are original issue and not female sperm cells, and any children I might beget are unaffected by the fact that I have blood cells with DNA not my own.
A nice thing about this is that you cannot steal my genetic engineering prowess and breed your own creatures carrying my edited genes which I worked hard on. Genetic modifications from my lab are not heritable and die when my modified individual dies. If you like the modifications I make and want some for your individual, hire me. Or coerce me to do what you want, if you are sure you will never be turning your back on my creations.
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I am writing a story about being "alone" on earth, I want it to be caused by a virus but I am unsure about the details of it.
I know that the virus:
* Should kill most of the worlds population leaving a few people to restart life.
* Must have a herbal cure/vaccine so that the protagonist can meet someone.
* Must spread all over the world at a speed that the news and governments don't
have enough time to fully report the problem.
My first thoughts for this virus is that it could be biological leading to an encounter between the protagonist and the antagonist.
It could be waterborne but then I wouldn't know what to do with the need to drink liquid.
I know I don't want a nuclear disaster to go off as I want the world to still be "inhabitable" after the outbreak.
**EDIT/CONCLUSION:**
I have combined the current answers and my own thinking. Since the protagonist is a software developer who has his own life like AI.
1. What if the world/humans relied on technology? like that movie called Wall E where the humans all got fat and needed technology to make them move. What if the Protagonists AI was an evil mastermind.
**OR**
2. What if humans wanted to spend more time with their families and go on holiday more? that boring jobs like nuclear waste management and repairing dangerous buildings were done by robots instead of humans.
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> Should kill most of the worlds population leaving a few people to restart life.
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That's easy enough. As the author, you can simply declare this to be so.
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A "herbal vaccine" isn't a thing; vaccines are made from weakened, inactivated or dismantled infection particles. They are also generally the end-product of a fairly sophisticated research and industrial process, so if one did exist for your virus it would have to have been made *before* the outbreak. There's a conspiracy hook for you.
A naturally occuring herbal cure also sounds slightly dubious, because the timescales involved make it largely impractical to discover in time to help anyone. If it *had* been discovered before, you've got another nice conspiracy hook. It might also facilitate the presence of groups of survivors who were already familiar with the herb and had been cultivating it for other uses (medicinal, recreational, agricultural, whatever).
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> Must spread all over the world at a speed that the news and governments don't have enough time to fully report the problem.
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You'll have a real problem with this. You can get realtime news updates from anywhere in the world if you have an internet connection these days. You might perhaps be able to handwave something that spreads silently and effectively with a long incubation period, then suddenly activates and kills everyone in short order.
In *Oryx and Crake*
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> a bioweapon is hidden inside a wildly popular pharmaceutical product, allowing its dissemination across most of the planet before it was activated and spread "naturally".
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In *The Stand*,
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> once the superflu (also a deliberately engineered bioweapon) outbreak becomes apparent it is deliberately spread by military agents already sited in foreign countries to ensure that *everyone* suffers from its creator's carelessness.
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There are many other fictional examples you could take; this is a very, very common trope. In *The Day of the Triffids*, for example, the titular hazards (which may or may not be bioweapons) spread far and wide long before a separate catastrophe prevents humankind's ability to keep society together, at which point the triffids become a massive and dangerous threat overnight. And so on.
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Modern water treatment is extremely effective at killing and filtering things down to the size of viruses, so this mechanism of spread seems likely to be a poor choice of infecting a modern society in a reasonably developed country.
Stick with the traditional means of spread, they work well enough. Measles is perhaps a good model, as it is extremely contagious and is spread in droplets that can survive on exposed surfaces outside of a host for several hours. *The Stand* uses a souped-up version of influenza, another favourite that can spread quickly and has been known to cause deadly epidemics.
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Earth is huge. It is really HUGE! No realistic pandemic illness (virus, parasite (malaria), fungi) can spread all over the globe in days or even in months. Even if it is spread intentionally. Even the worsts (deadly!) pandemics in human history never hit even a percent of all living humans on Earth at that time (okey-okey, Spanish Flu - never hit even a third of population! But still less then percent of Earth's population of die off - it was not as deadly for infected as plague in medieval Europe)
So, you will need a very long incubating period, low virulence - danger by itself (if people die too fast, virus would die off with them, leaving great number of quarantined survivors), inability of modern medical institutions to find any cure for decades.
My preposition: make HIV to be transported by skin contact (or/and by air - like flu). It will infect all the population rather quickly (in a decade or so), and silently (no visible symptoms for years - a lot of people will be infected without knowing it). Humans will start to massively die off in about 2-3 decades from start of mutation. Even those who are not infected - due to pandemic of other opportunistic infections, like tuberculosis or superflues, or many many other. Little can be done in this scenario, even if HIV mutation is detected immediately - you can't guarantee that you have all infected in you quarantine, due to lack of symptoms.
To defeat it humans need to mutate by themselves and find a way to spread this mutation among survivors.
All this process of extinction would last for about century or so, with pike of die off at 40-50 years from year zero.
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**Space germ**
Good old [Andromeda Strain](https://en.wikipedia.org/wiki/The_Andromeda_Strain)! Supergerms from space.
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> The Wildfire team, led by Dr. Jeremy Stone, believes the satellite -
> intentionally designed to capture upper-atmosphere microorganisms for
> bio-weapon exploitation - returned with a deadly microorganism that
> kills through nearly instantaneous blood clotting. Upon investigating
> Piedmont, the team discovers that the townspeople either died in
> mid-stride or went "quietly nuts" and committed bizarre suicides.
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The good thing about space source is you can have the germs trickle down uniformly thru the atmosphere. Also space germs can violate terrestrial biology. If you need to get into the weeds about how exactly the space germs work, you can invoke alien biology, human engineered bioweapons (with work being done in space to prevent contamination) or even alien engineered bioweapons with the aim to clear off earth life and allow colonization.
Crichton even presents the possibility of fluky chance immunity as you want for your scenario; see link. For example, your protagonist is growing Chinese herbs in a greenhouse in Wisconsin and often sleeps in the greenhouse. High blood levels of two of these herbs are needed to block infection. Because she is in the business, she already knows the other survivor: her eccentric customer in NY.
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This is similar to something that I have thought about a few times.
As Ksbes has mentioned, the Earth is a really big place, and most natural viruses that could fit your scenario either spread to slowly, and are discovered before it has a massive impact, or are so fatal that it cant spread fast enough.
So we have to look at a bio-engineered death bringer. It is made by a well funded group of people, as bio-engineering is extremely complex, and out of the scope of a one man operation. This group wishes to bring destruction to the west, and decides to release their virus. They are not stupid, and so have a bit of strategic planning for this release. They target several of the world busiest airports for the initial infection. (The worlds current busiest airfield is Hartsfield-Jackson Atlanta International Airport (Georgia, US) -- 107.4 million passengers traveled through in 2018, a daily average of 294 246 thousand passengers). The combined top 5 airports have almost 1.3 mil daily passengers. The virus is an airborne pathogen released into the air vents from a powdered source like anthrax.
After initial infection the virus has an incubation period of 7-10 days, after which the first symptoms appear. These are very minor, and only intended to spread the virus further, and include coughing and sneezing and a runny nose. During this stage it is extremely infectious and spreads rapidly to everyone in close proximity to the initial infected. After about 5-9 days, the symptoms clear up, and the virus begins to progress to its final stage. This stage has rashes, boils filled with virus pus, open blisters and respiratory problems similar to TB. The victim will finally die from multiple organ failure/ total system shutdown. The last stage last for about a week, giving a total time from first infection to death of 20-30 days.
Take away points:
Bio-engineered, so will be believable with small amount of hand waving.
Large scale initial infection. +1 for carrying out during a peak travel time, such as before Christmas/New Years. +1 If you release virus over a 2-3 day period, increasing the inital infected population.
Incubation period allows for infected to spread out relatively far before symptoms first occur.
Minor symptoms, no one goes to the doctor or hospital for the common cold, which this mimics.
Highly contagious, think about the common cold, when one person in a house gets it, within a few days, everyone in the household has it.
Hard to prevent death, organ failure is one of the hardest medical complications to stop.
+1 that by the time the final stage starts for the first infection group, a majority of medical professionals are also getting sick.
And a final +5 if you have the dead bodies, with all their open blisters and leaking boils, highly contagious like Ebola.
Should also fly under the radar for long enough, as no news channel is going to report on the unusually high number of cases of the cold this season. Once it is seen that its extremely serious, well, to bad and to late.
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To produce large numbers of deaths there are certain things a disease has to do.
It has to be easily transmitted. Airborne is probably ideal, especially in this age of international travel. But transmission through sweat is pretty nasty. So you want something that can be transmitted through brief non-direct contact. Somebody sneezes and it infects a room full of people. Somebody touches a door knob and it infects the next thirty people who also touch the knob. Somebody uses a cash machine in an airport and it forms the nexus of a new source of infection. Somebody pumps their own gas and the next 50 people who use that pump get infected. And so on.
Next, it has to have a long period where it shows no symptoms but is still infectious. If everybody who gets it starts feeling sick within minutes they won't have time to infect anybody. And the authorities will know something is up very quickly. If nothing else, the elites will hide in their basements and avoid getting infected themselves. So if nobody has symptoms for, say, three weeks, it gives the disease time to spread around. You can even have some good chance at getting to lots of those semi-nomadic tribes who have their once-per-week visit from the tourist-locusts. Snap-snap, grin-grin, tip-tip, infect-infect, say no more. It will even have a good chance at catching some of the people who work in various military bunkers but get every other weekend home with the family.
As to a "herbal remedy" that's kind of tough. Maybe a herbal control. I'm thinking of tonic water and malaria.
So what about: air borne malaria with a three week latent period?
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You could have it spread on purpose by some shadow organization.
They might even have "good" intentions, reducing fertility with the virus to reduce human population as a smooth way to safe the planet or something like that. But something went wrong and the virus that was intended to sterilize half of the infected now kills 99% of them.
There is another problem though that pretty much always gets ignored when a scenario like that is invented. You want the planet to stay inhabitable and therefore you don't want a nuclear disaster. But by killing most of the population you will get a nuclear disaster anyways.
There are about 450 nuclear reactors worldwide, with about 60 more being built at the moment. And thats only the civilian ones.
Without technicians to keep them in order and a supplying industry that delivers spare parts, they will all melt down. And not only the active reactors, also the stored nuclear waste from reactors, when not actively kept cooled will eventually melt and polute the environment.
Same is true for chemical waste dumps and alike.
So removing humans in short time will always result in a massive environmental disaster.
Also removing them slowly through distress will very likely have the same result, as a dying human race would probably not care enough to make sure the leftovers don't poison the planet and instead focus their efforts on avoiding their own extinction.
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A pandemic is caused by the spread of an extremely *contagious* virus, likely either airborne or droplet-borne. On top of that, you need a lot of international travel and either ignorance, apathy, incompetence, or malice from governments and other organizations for the virus to travel across borders.
The problem here is this requirement:
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If this were true for a virus, it will set off alarm bells, triggering swift response of targeted quarantines that contain the virus and keep it from becoming a pandemic. Pulling from recent history, part of the reason that governments did not act early enough to contain COVID-19 was because the virus is *less deadly* than its cousin, SARS. It did not raise alarm bells in the same way that SARS did. Perhaps things may have turned out differently if it were more severe, but that's just speculation from a layman such as myself.
If the virus is deadly enough, it makes nuclear bombs a viable containment/eradication strategy (albeit overly destructive), which only costs a few million lives instead of 99% of the world's population. If the outbreak started in a highly authoritarian country with no respect for human rights, you can bet your ass their government is not going to have any qualms with dropping a nuke on the source of the outbreak.
There's also the issue of how such a virus would evolve. Natural selection tends to select viruses that are contagious but not very symptomatic because populations can and will adapt to its presence. People might start wearing masks or isolate themselves in order to reduce the spread. Viruses do not have goals and the ones that proliferate are the ones that either aren't symptomatic (and thus don't give any reason for the infected to wear a mask) or are somehow contagious/robust enough to counteract common mitigation measures. The virus isn't driven by some deranged mastermind plotting to kill humanity.
This kind of suddenly-deadly virus does not mutate overnight, nor does it mutate in lock step. One virus "cell" (or whatever a single instance of a virus is called) might have picked up a mutation and survived to infect a new host. Maybe it's a little more severe or a little more contagious. But it's astronomically unlikely that a freak mutation is going to change a virus enough for a single virus particle to conquer the world. **It's going to have to be genetically engineered to get what you're looking for**.
There's also the issue that a virus that almost always kills its host is going to have trouble spreading. Ebola never really made it outside Africa, for instance, and it had a death rate of 90%.
Honestly, you don't want a virus for this kind of plot point. You want divine intervention a la Noah's Ark.
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49).
Closed 4 years ago.
[Improve this question](/posts/149456/edit)
High-tech Ents foresee a calamity befalling their beloved and treasured green planet. Surface temperatures will rise well above 500 Celsius (arbitrary, basically just very hot) for thousands of years, before cooling back down.
They enact many preservation plans, one going towards space, one going underground. Their rocket science is very limited, but their bioengineering is at near miraculous levels. For this reason they prefer to go underground, where they have less initial limitations.
(All other tech, especially material manufacturing are high level too, since nature produces some amazing materials)
They have the capability to dig deep and create huge cavern habitats with different biomes to save much of their current wildlife. They already modified numerous organisms to manage water and waste recycling, humidity, inner temperature, oxygen (air), light, etc. and they are mostly autonomous, requiring no maintenance. They will however need constant energy and produce heat.
The underground habitats will be surrounded by extreme high temperatures from below (core heat) and above (the calamity), closed off from natural sunlight (free energy).
**So the Ents face 2 big problems:**
1. Even fully insulated from outside heat, all life produces heat. If they can't dump the excess heat, they will eventually cook themselves. Especially that their environment maintaining organisms produce even more than normal. Storing it in some form is not preferred for fear of the calamity lasting longer than calculated.
2. Even with vast stockpiles, they can't store enough energy inside these habitats to last forever. They will have to generate it some way using their current environment.
These are the two main problems the Ents identified so far, and can't solve without handwavium technology. The Ents, close to nature, abhor any form of handwavium. However in order to save the many lives of their world, they are prepared to put up with the least amount of it.
Is there a reasonable scientific way to solve the problems given the circumstances? If not, what type of handwavium should the Ents invest?
The solemn Ent researchers look towards the starry sky for answers.
Edit: though it isn't the main issue, the Ents envisioned their habitat's "shell" as layers of high melting point, low heat exchanger material with close to vacuum conditions in between. They still looking into the best composites, but figured if they can dump the inner heat outside, they could do the same with any leaked in heat.
Edit 2: The "miraculous" bioengineering is their own, arrogant estimate. Basically, they can produce machines and infrastructure which take care of its own maintenance, given steady energy supply. It also helps with the long-term self-sufficient biome designs, given the 2 connected problems solved.
Edit 3: Ents - tree like plantoids, sentient, biological. Technology, culture somewhat similar to humans but more heavily emphasize co-existence and symbiosis with nature.
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In short, it's a tough engineering problem, but it's not a physically impossible one.
500 degrees Celsius might sounds like a lot, but it's really not that bad. Aluminum melts at 659 C, and steel at 1371. That means we can use heat pumps to concentrate the heat from the habitat and raise it to a temperature higher than the 500 degree exterior, which means we can reject it to the exterior.
This process will require energy, which will generate more heat, which will require more energy, but calculating the exact optimum point where your heat rejected is maximized compared to your heat generated depends on a slew of technical assumptions and I'll leave it as an exercise to the reader.
Now, a few suggestions:
-Seasponges actually have an internal structure somewhat akin to aerogel, which is an excellent insulator, so biomimetic aerogel insulation is something you might look into instead of vacuum chambers which are more annoying to work with from a technical standpoint.
-Geothermal energy might not be the best bet. It depends on the location, if there's a nearby source of geothermal energy, that might work, but otherwise it might be better to use nuclear, it's a lot more energy dense so you can store enough fuel for thousands of years of operation, and you're not limited by geography on where you can put your bunkers.
-Finally, you might not even need underground bunkers, the main use of them would be to protect you from the high surface temperatures, but if the planet's top layer is also heating up, you'd be better served not dealing with the hassle of digging out these bunkers and instead just make a bunch of insulated spherical habitats on the surface.
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To build on Algebraist's answer, I would use thorium rather than conventional nuclear reactors. Depending on where you build the bunkers, you could collect the thorium while you dig, and you wouldn't have to deal with all the radioactive waste once the nuclear fuel is spent. And even if the reactor would spend most/all the fuel, you would have to maintain the complicated safety systems that conventional reactors require
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The power required for cooling will be relatively significant, but not enough to make things wholly impossible. Although thermodynamics tells us that we must expend more power on cooling than we use in the habitat and this could limit things.
[Coefficient of performance](https://en.wikipedia.org/wiki/Coefficient_of_performance) for air conditioning is COP= T\_Cold/(T\_Hot-T-Cold), so assuming the average temperature inside is 20 C, the maximum coefficient of performance we can get is 0.61. This presents a predicament because it means that we must spend at the very least 1.6 the energy we expend in the habitat on cooling. So maximizing efficiency is of utmost importance here. I'm going to arbitrarily consider [a spherical habitat 110 meters in diameter](https://markozen.com/2018/11/15/super-cool-sphere-arena-in-stockholm/) with an arbitrary 1 meter thick layer of insulation. We choose a sphere for ease of analysis and also because spheres are the best at minimizing surface area as we increase volume. So going from one of NASA's studies on making [a rover for venus](https://www.researchgate.net/profile/Anthony_Colozza/publication/268569312_Venus_Rover_Design_Study/links/563a285508ae405111a57d2e/Venus-Rover-Design-Study.pdf) with a cooled interior for electronics, we'll use [multilayer insulation](https://en.wikipedia.org/wiki/Multi-layer_insulation). This might give us the most bang for our buck and may even outperform aerogel at these temperatures. Assuming a temperature difference of 480 K between the layers and that we have near vacuum, [plugging into a handy study NASA did on multilayer insulation](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080013560.pdf) we find that a thermal conductivity of 0.02 W/(m\*K) is reasonable to assume.
So the heat transfer through an spherical shell with inner radius r1, outer radius r2, inner temperature Ts1(20 C) and outer temperature Ts2(500C), and thermal conductivity is given by Q=4\*pi*k*(Ts1-Ts2)/((1/r1)-(1/r2)). Plugging in the temperatures(in kelvin) and radii we find that we need to get rid of ~37 KW of heat. Assuming we get a coefficient of performance of half of the thermodynamically ideal coefficient of performance we find that we need to expend 37KW/0.305=122 KW to remove this heat. This is a fair amount of power, but not utterly unreasonable. As we increase the diameter of our spherical habitat, the ratio of heat we have to remove relative to the cooled volume we have decreases.
Power generation becomes a bit more difficult as we must reject heat to a 500 C environment. The inside of our heat engine needs to be much hotter than the environment in order to be efficient. We could potentially use a [very high temperature reactor](https://en.wikipedia.org/wiki/Very-high-temperature_reactor) for power, where it's possible to achieve outlet temperatures of 1000 C. Another interesting option is a [fission fragment reactor](https://en.wikipedia.org/wiki/Fission_fragment_reactor), where we can avoid heat engines entirely and harness fission almost directly. There's always fusion.
A challenge is that it seems you are using bioengineering for everything. There aren't many organic materials which are stable at 500 C and above. Getting biology to produce metals and ceramics which are stable at these temperatures may not turn out to be possible.
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Going underground has the advantage of insulation for relative cheap. And with a large degree of robustness. Fifty meters of rock is going to be very good at insulating, and also very resistant to minor things like weather. You'd need to have a good knowledge of the geology and earthquake frequency and such to be confident of the vault. But that could certainly be approached with some fairly easy things. If there are million year old caves nearby, probably the geology is OK, just as an example.
But after 1000's of years they will need to have some kind of cooling. How well they can manage that depends on how much energy they can generate. If they are OK with nuclear power, for example, they could run some honking-big A/C units. The exhaust side, on the outside of the habitat, needs to be hotter than 500°C in order to lose heat. So possibly the working fluid is interesting to choose. Maybe the A/C units need to be staged to be sufficiently efficient. One stage moves heat from the habitat to an intermediate step, using more ordinary A/C units. Another stage moves heat from there to outside using some yet-to-be-designed A/C units with some interesting new design. Off hand I don't know what fluid to select to work in the range of 500°C, but it's likely something could be found.
Nukes operating with a "cold" side at 500°C are possible, but they'd be a challenge. The working heat transport fluid might be lead. There are designs on the blackboard now for [reactors that use molten lead](https://en.wikipedia.org/wiki/Lead-cooled_fast_reactor) as coolant. It's conceivable they could have most of the actual reactor completely outside the habitat in order to keep the heat loss problem as small as possible. Only the control systems and computers need to be inside.
Nukes will also help them generate light. I presume ents will want light, probably with a spectrum as similar to sun light as reasonably achievable. Some good LEDs will be useful there, efficiently producing light while producing minimal heat. Pick them to produce the right spectrum and the ents will be less depressed at being underground.
They might need to develop various tech to go with. For example, they might need to make brief trips outside to maintain equipment, take observations, obtain raw materials, etc. So they would need insulated suits with air and cooling. Possibly tanks of liquid air would cover both.
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Instead of making a bunch of extra heat by piping in geothermal energy or running nuclear power plants, just create a self-contained Power/Heat Cycle.
Plants already sequester thermal energy into chemical bonds; so, if I were to try to solve this problem thinking like a plant person, I would try to find a way to turn my heat into yummy starches. The creation of these complex organic molecules is an endothermic reaction which would sequester your heat into chemical compounds cooling your caves. Done right, these chemical compounds could then be processed into biodiesel that is burned to power the lights and other technology while releasing your CO2 back into the air to be reused. Burning the fuel would in turn heat up your cave system feeding your heat sequestering plants all over again.
By keeping your own thermal/power economy balanced using local reserves, the only heat you'd have to worry about would be from the outside, but your heat based economy would help you here too. As you're cave heats up beyond what it should be, your sequestering plants would go into a bloom, reproducing and growing faster as the additional heat feeds them. This would mean extra fuel to power the fancy heat exchangers as discussed in some of the other answers here.
Normally a self-contained Power/Heat system like this does not work in the real world because your heat is always radiating off to somewhere colder, but in this case being sandwiched between two heat sources is what makes it sustainable.
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1. **Phase change of water**. A great way to soak up heat is via phase change. The ents are aware that the crust contains vast stores of liquid water. They vent that water to the surface, accumulating enormous quantities of it. When the heat come the water acts as a buffer, absorbing the heat as it changes from liquid to gas. The surface water also buffers the underground by virtue of its great heat capacity.
Moving and evaporating water seems like good nature tech.
2. **Iron fusion.** This is not terrestrial magic as much as sidereal magic. Fusion of elements below iron releases energy and fuels stars. Fusion of iron or elements higher in the periodic table absorbs energy and kills stars.
<http://abyss.uoregon.edu/~js/ast122/lectures/lec18.html>
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> Higher mass stars will switch from helium to carbon burning and extend
> their lifetimes. Even higher mass stars will burn neon after carbon is
> used up. However, once iron is reached, fusion is halted since iron is
> so tightly bound that no energy can be extracted by fusion. Iron can
> fuse, but it absorbs energy in the process and the core temperature
> drops.
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This process is why stars die: they are cooled to death as fusion of iron drinks heat and changes it to matter. If this process can cool a star it can cool your world, and make it a little heavier. Alright arrogant tech wizards: saddle up!
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help).
Closed 4 years ago.
[Improve this question](/posts/149189/edit)
I read somewhere that scientists are trying to create nanobots carrying functional mitochondria to search out cancer cells and restart apoptosis. Instead of trying to create nanobots with a fully functioning mitochondria, would it be easier to create nanobots that search and destroy cells with broken mitochondria or excess glucocytosis instead?
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The theory is that nanobots that destroy cancer cells could leave hunks of necrotic tissue in your body.
Ideally, your body would re-absorb this and heal the wound over time, but this is not always viable. Stomach cancer for example can be difficult to treat right now because destroying the cancer risks leaving a hole that would spill bacteria and stomach acid into your abdominal cavity killing the patient from septic shock much faster than the cancer would have on its own.
Currently we work around this when we use radiation and chemotherapy by applying many-many doses over a long period of time to kill some of the cancer with each treatment, then give your body time to heal before the next dose. Destructive nanobots could do the same thing, but it would still take a long time to work which may make it inadequate for treating late-stage or highly aggressive cancer.
Repairative nanobots don't need to be scheduled out. One dose could halt the spread of cancer by repairing all the damaged cells at once because you would not need to wait for healing. In the process, the repaired cells could also be marked for selective removal later with a slower, controlled wave of destructive bots if need be.
It's not so much a question of if destructive nanobots are easier to make. The point of the research is that using bots that can repair the cancerous cells may be able to return the tissue to normal function without causing any unnecessary trauma and open up new options for treatment.
As a side note: Modern medicinal Nanobots are not actually robots at all. They are engineered viruses; so, once they are in your blood, they don't just swim where you want them to go and do their thing, they will spread through your body, with the potential to do things in unexpected places. Another possible advantage of using them to carry a set amount of mitochondria, is that you limit them to the point they expend their payload whereas a destructive one may lie dormant in your system and cause unforeseen issues in the future.
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> would it be easier to create nanobots that search and destroy cells with broken mitochondria or excess glucocytosis instead?
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No, I don't think it would be easier.
**Probing a cell for being cancerous** can be done from the outside of the cell itself, via the surface proteins. This makes easy to give the nanobot an appropriate receptor, that attaches it only to cancerous cells.
**Probing a broken mithocondrion** requires entering the cell and test one by one all of them. This is more difficult, because it would require an active motion of the nanobot into a dynamic environment.
**Probing a cell for excess glucocytosis** is even more difficult: it requires the nanobot, or someone for it, to check the input and output of all the cells and then asses if they are within glucose budget or not. Yes, you could attach the nanobot to a glucose molecule, but that would be not much different from a normal chemotherapy targeting replicating cells: you would have casualties also among healthy cells.
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What you are describing behaves more like a phage than the most modern immunotherapies. You are correct, according to what I've read and listened to in lectures, that one approach to treating cancer is by activating the bodies immune response to start recognizing the cancer cells as damaged. As has been inaccurately described in other answers, cancer is not a single mutation.
Cancer's life cycle is a sequence of mutations that cause it to hide from the body's immune system, grow wildly, then sometimes become mobile and move around the body (metastasize), find a new home, and start growing again.
The way it was explained to me was that each change in behavior is the result of a series of mutations. That is why recognizing which cells are mutated in a bad way and are malignant is difficult. Since we have random harmless mutations and dark codings in our DNA. We pick sequences from viruses and bacteria we encounter over our lives. They don't always cause us harm or benefit.
So playing one of these cells is not like the other on a genetic level is hard. If a nanobot killed cells based on just 'it is different' and not 'it is malignant' then we'd be reduced to pudding.
But, phages are natural critters that attack and eat specific bacteria -- each phage species eats a very select set of bacteria. And, ignore the others. They were a big topic of research before the development of antibiotics. The west stopped looking into them since we had the wealth to research new antibiotics. The Soviets didn't have that money so they stuck with phages. Now, in the time of drug resistance bacteria, phages are of renewed interest since they don't hurt people and they like to each thing bad for us. A [recent book](https://rads.stackoverflow.com/amzn/click/com/0316418080) on the topic details one couple's encounter with an obscure disease. The husbands'life was saved in the last moments with phages.
Anyway, if your nanobots were designed with the discriminating sense of your typical phage, just going after a specific set of properties and chemical signatures, then as a story it would be believable. I think though killing the cells could generate a lot of debris in the blood, in the case of widely spread cancer, and could overwhelm the liver and kidneys to filter it out. I liken it to being struck by lightning and living. You often die later because of necrosis breaking down the cells and destroying your liver (or kidneys, or both.) But, if you are smart and go to a hospital, they put you on dialysis and you live.
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Cancer is essentially a malfunction of the body’s cellular regeneration system. An error if you will, in the accuracy/fidelity of replicating the same DNA pattern. This happens sometimes completely at random at sometimes with the help of damage to the DNA from toxic substances, radiation or just degradation from old age. Each cancer therefore has a random and unique genome that in theory a properly programmed nanobot patrolling the bloodstream might be able to differentiate from a digitally stored profile of the patient’s original genome.
Depending on how successful the bots are at identifying cancers in the body, you might then be able to flag the cancers with chemical markers in a way that the immune system can then recognize and attack. That would at least get rid of the tumors but it won’t necessarily solve the fact that your DNA replication is getting errors. And it’s not going to be helpful if the bots misdiagnose healthy tissue which might be unavoidable since the body is continuously regenerating itself and it’s using your DNA as the blueprint for that.
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To help you get the idea of what I mean, here is an example of the edge. Imagine the edge can move like a chain sword or chain saw, so don't take it too literally. Don't consider the entire sword shape in this example, just the edge. Imagine the design similar to a [macuahuitl](https://en.wikipedia.org/wiki/Macuahuitl) sword, if you don't know what a chain sword or chain saw mechanism looks like.
**Macuahuitl flat edge?**
[](https://i.stack.imgur.com/u8FCF.jpg)
**Shark edge?**
[](https://i.stack.imgur.com/k54GK.jpg)
**No gap or no serrated edge?** Just a normal sword but the edge moves like a chain saw or chain sword.
[](https://i.stack.imgur.com/6dz8n.jpg)
**Or maybe a wavy or half circle edge?** (almost wavy, but with more gaps, and the gaps are flatter, so something like a small axe blade positioned into a macuahuitl style sword)?
[](https://i.stack.imgur.com/v8V7w.jpg)
Or you can suggest different edge styles and provide a reason, if possible, in your answer.
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It depends on what you want to cut.
A chainsaw works well on trees as it tears pieces off and flings them away. On a human you wouldnt just tear pieces off but also pluk out sinew, tendon, pieces of muscle etc. This would quickly foul up the mechanism.
Swords have different styles. In Desert regions where metal armor is almost a death sentence and leather was predominant the swords were mostly Curved. This was so that if you sliced your enemy there would be more of the sword's edge cutting passed the leather and cut through. These swords were less about bludgeoning through your enemy for that reason. A similar approach is probably best for your chainsword. The wielder will aim for places where no armored plating is present such as arms, neck, leg or the joints. If necessary the wielder can even try to cut the plate holder so the armored plate falls out before finishing the opponent.
If you really want to go space-marine and chainsword through armored opponents I would redesign it into a multi-buzzsaw sword (buzzsword?). You have 4 blades in parallel with as many rows as possible on the blade. The first parallel group has the outer two spinning the same way and the inner two the opposite, the next row has this in reverse etc. This way if you hold it against a target the blade will not try to pull out of your grasp or try to spin. The target will be "pulled in" by the blades as they grind off material. The engine inside can work through pressure, and any buzzsaw that is depressed will get shifted into gear so the energy of the engine is as well distributed as able (ofcourse they would be spinning on idle before being depressed). Unlike the space marine chainswords the (blooody) material sawn off wont be launched onto their abdomen and legs but be pulled out the other side of the blade. If you want you can create a compartment so you dont spray the buddy next to you, and have a small portion of the engine relegated to flinging the pieces of armor, clothes, bone, flesh, blood and gore you just accumulated out the front of the buzzsword and into your opponent for some psychological warfare. "here's your buddy I just buzzsawed in half right back at you". Yes I'm assuming you have the technology and bodybuilder soldiers to make a heavyweight buzzsaw worth it, you can swing a dam chainsaw like a sword so this shouldnt be a problem.
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The problem with chainsaws is that they are not particularly effective weapons. Cloth can easily get pulled inside the mechanism and cause the saw to sieze up, requiring it to be disassembled to remove the material.
Additionally, there are the problems with weight and fuel consumption, an issue for a weapon as slower weapons are more unweildly and you could easily run out of fuel in a fight.
[Here is a video demonstrating the chainsaw’s flaws as a weapon](https://www.youtube.com/watch?v=COlgpvb7ggY)
However, if you were set on using a chainsaw-like motion for your blade, i would suggest using the flamberge (a wave-like blade, like the one pictured in the question) as this is less likely to get caught on materials and drag them into the mechanism.
You may also want to consider a Jigsaw motion where the blades move up and down, rather than in an ovular motion like a chainsaw. This gets the sawing motion you may want but with a reduced risk of material getting stuck. You could have just the edges of a sword be replaced by these blades so the whole sword blade is not moving up and down.
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Cutting is a very well understood process - but sadly also very dependent on some variables that are not mentioned in your question, namely the material being cut, the speed with which the sword is supposed to pass through the material, and the speed with which the chain is moving.
I am going to assume that the variables are to be set by the answerer: Everything, 30m/s, 12000m/s (yes, that's alot)
Sword-Speed is negligible to chain speed, therefore subsequent teeth will not encounter much additional material. This is both good and bad: Good in that there is not much mass to be displaced by each tooth, bad in that the edge takes the brunt of the force, and will thus blunt fast. It means you'll not have a circular chain, but rather something that is unspooled from a source and used only once. The teeth can be extremely small, the leading edge practically vertical, the edge, then a taper;The teeth might be so small the edge looks flat from the enemies perspective (and moving will appear so for sure)
12000m/s is the speed of sound in diamond, so there should not be many materials able to withstand this sword. On the edge. As this presumes a one-off chain, the source needs be in the grip, and the chain is left to unspool freely. To cut through 3 m of material will take you 1/10 th of a second, meaning 1200m of chain get unspooled. A sword grip being about 0.0001 m3 large, this comes out to about 10^-8 m2, or, for instance, 1 mm broad and 10 um thick (making the teeth be at the very limit of haptic sensibility (unmoving)). The blade cannot be thicker than the chain is broad, but thinner is better here anyways, as we do not want to move too much material.
How to get the chain up to speed is left to the reader..
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I am asking specifically because I was recently doing a *Doctor Who* marathon and saw the apalapucia episode and thought "I wonder if that's possible?" So here I am. Is it possible to have a planet where time passes at different speeds at two different locations? Such as: one hour at one place equals a half second in the other.
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To the question in the title: **No.**
To the question in the body text: **Yes.**
You want a planet orbiting an extremal supermassive Kerr black hole--supermassive so that you can get close to the event horizon without being shredded by tidal forces, and extremal so that the innermost stable orbit is also close to the event horizon. For a non-rotating Schwarzschild black hole, the innermost stable orbit is 3 times farther out than the event horizon, and you don't get particularly strong differential time dilation. But the faster a black hole spins, the closer in the innermost stable orbit gets. If the planet can orbit just outside the event horizon, the side closest to the black hole will experience extreme time dilation, which will fall off fairly rapidly such that time at the opposite "pole" runs noticeably faster.
Such a planet would not actually need a sun, either--the black hole acts as an equally-effective "anti-sun". Rather than having a fairly concentrated heat source (sun) and radiating waste heat into a cold background sky, an extremal black hole planet would be warmed by the blue-shifted background radiation of space, and would radiate waste heat into the cold black hole--which, due to gravitational lensing, would cover an even larger portion of the sky than you would naively assume just from being really close to it.
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We already live on such a planet. Welcome to Earth, and more specifically to the [Large Hadron Collider](https://en.wikipedia.org/wiki/Large_Hadron_Collider) (LHC) and other similar places, where particles, accelerated to a significant portion of c, experience the time dilation forecast by the theory of relativity.
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> The protons each have an energy of 6.5 TeV, giving a total collision energy of 13 TeV. At this energy the protons have a Lorentz factor of about 6,930 and move at about 0.999999990 c, or about 3.1 m/s (11 km/h) slower than the speed of light (c).
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Oh, it also happens in the high atmosphere, where elementary particles generated by the nuclear interactions experience relativist effects.
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If you want [science-based](/questions/tagged/science-based "show questions tagged 'science-based'"), the answer is a clear **NO** as far as early 21st century science is concerned. The only things we know to "distort" the flow of time are very high speeds and very high masses -- very high on an astronomical scale. This cannot happen on a planet.
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If time has a second dimension (moving from a timeline to a time-plane) then yes, as you can have a variety of time parabolas moving through the time plane at angles to the main timeline, thus giving whatever moves through these other timelines time dilation, which can be extended or contracted.
Some links if you want:
<https://phys.org/news/2007-05-two-time-universe-physicist-explores-dimension.html>
<https://bigthink.com/philip-perry/there-are-in-fact-2-dimensions-of-time-one-theoretical-physicist-states>
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So I'm currently designing an alien habitable planet that orbits a star similar to our Sun. Assuming that the composition of the planet's atmosphere, as well as its pressure, are similar to the ones on Earth, would plants on this planet have any other color than green?
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Plants come in many colours anyhow, [Chlorophyll](https://en.wikipedia.org/wiki/Chlorophyll) making the base colour green for most, other pigments occur naturally too; [Carotenoids](https://en.wikipedia.org/wiki/Carotenoid) - ranging in colour from yellow/brown to dark green, [Betalain](https://en.wikipedia.org/wiki/Betalain) - red and yellow, [Anthocyanins](https://en.wikipedia.org/wiki/Anthocyanin) - red purple or blue.
Chlorophyll is of course green but if your plants used other compounds instead they could be different colours.
* [Bacteriorhodopsin](https://en.wikipedia.org/wiki/Bacteriorhodopsin) (purple) was first used by [Archaea](https://en.wikipedia.org/wiki/Archaea) billions of years ago on Earth and acts as a proton pump:
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> it has an appreciable detected emission for excitation wavelengths
> between 470 nm and 650 nm (with a peak at 570 nm)
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* [Melanins](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4125832/) (brown, red) It has a wide absorption spectrum covering the whole of visible light into the ultraviolet and can break down water, and is thousands of times more efficient at it than chlorophyll.
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> it is considered the world's most important reaction since it is the
> beginning of the food chain. Therefore, a plant without water will not
> hatch, since the free chemical energy that is released with the
> breakdown of the molecule of water is essential to boost consequential
> reactions
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The chemistry of photosynthesis is driven by chemical reactions - which are driven by shifting electrons about between atoms/molecules - sometimes because that's the way they want to go - sometimes because they're given a kick from outside (photons) - essentially a gradient.
[Nanotechnology](https://www.understandingnano.com/solarcells.html) to generate electricity - electron/proton gradient pumps have evolved in the above forms. They have also been created by people in so many forms: [Honeycomb graphene](https://www.understandingnano.com/3d-graphene-solar-power.html) structures, copper indium selenide sulphide [quantum dots](https://www.understandingnano.com/quantum-dots-solar-cell.html), [graphene sheets](https://www.understandingnano.com/graphene-lightweight-solarcells.html), [graphene coated with zinc nanowires](https://www.understandingnano.com/graphene-zinc-oxide-nanowires-solar-cells.html). If we can make it, who's to say it can't evolve in nature and better. Curiousley, many of them appear blue/black.
Ways to produce [colour effects without pigment](https://www.huffingtonpost.com/researchgate/how-nature-uses-physics-t_b_13167572.html?guccounter=1&guce_referrer_us=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_cs=WK8MJo9km8hfZ16k-azgEQ) such as by constructive and destructive interference on a nano-scale such as in butterfly wings could evolve.
[](https://i.stack.imgur.com/168iK.jpg)
*Credit [Kevin Walsh](https://www.flickr.com/photos/86624586@N00/)*
# In fact they have:
*[Pollia condensata](https://en.wikipedia.org/wiki/Pollia_condensata)*
[](https://i.stack.imgur.com/btsG0.jpg)
*Wikipedia 2019 CCSAL [Licence](https://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_License)*
Your options are open wide.
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There are multiple theories, why clorophyll is dominating on Earth. [Source](https://www.zmescience.com/other/science-abc/why-are-plants-green/)
Theory1:
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> One theory is that early oceans were filled with purple microbes called archaea. The light-sensitive molecule in these microbes is called retinol, which absorbs green light and reflects red and violet light, which makes them appear purple. So parts of the earth could have looked purple! All the green light was taken by archaea, so chlorophyll had to make do with blue and red light. However, chlorophyll-based life became much more dominant because even though it uses less of the light spectrum, chlorophyll is much more efficient.
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Theory2:
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> Another theory is that **absorbing too much light could damage the plant** more than it would help, much like how when we get too much sun, we get a sunburn. So it could be beneficial that the plants are getting less light.
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>
>
So I assume, that if everything is similar (distance to sun too), then sooner or later clorophyll is going to take over. But, if the distance to sun is different, or temperature is different, there might be a need for more efficient photosynthesis - it could work with different molecules on different wavelengths.
[Answer]
Most likely yes.
One of the big factors that give (most) Earth plant-material it's predominant green color is the chemical Chlorophyll. This is a major component of the chemical complex that allows a plant to absorb solar energy.
On a different planet, with total different biology the odds are high that "plants" or their local equivalent use something entirely else and therefore may have radically different colors even if everything else is much the same as on Earty.
E.g. If you local plant life, due to its chemical/biological composition, is most efficient in absorbing energy in the blue and UV part of the spectrum, it wouldn't make much evolutionary sense for those plants to have blue/UV colors as every bit of light in those colors reflected isn't benefiting the internal workings of the plant. So those plants would probably reflect anything BUT blue/UV and look to be yellow/orange/red in color.
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[Question]
[
I'm looking for an alternative for horses. Why not horses? the short answer is the gods didn't want to create them. The gods in my universe like to annoy humanity. Horses only seem to really benefit them and not the other favored races, My humans are semi-nomadic with a culture of cavalry warfare including horse archery. I'm looking for alternative animals I might be able to justify in universe. So I found this [question](https://worldbuilding.stackexchange.com/questions/18828/realistic-alternatives-to-horses) and it doesn't fully answer my own question. My world has two constraints not seen in the original question.
My humans originate in a climate pretty similar to the savanna, north Africa and the Levant. Large open plains but very dry. So my restrictions for an alternative are, adaptable to a harsh dry climate, must be able to carry a rider over long distances, temperament that makes them usable on the battlefield and their gait must allow for mounted archery.
It's not required they have all of the above traits out of the box. Humans first used wild donkeys for their chariots before switching to horses and it took ages to breed ones large enough to be ridden. So I'm willing to take the time to breed this animal into a formidable mount.
[Answer]
Behold your savior - *Taurotragus*, the elands: [](https://i.stack.imgur.com/xCeXX.jpg)
Common elands (*T. oryx*) come from many parts of southern Africa (a region apparently irrelevant in your alternate world), including the Kalahari, and the 'giant' eland (*T. derbianus*, however, they're only slightly larger) is native to the savannas, scrublands and sometimes even deserts just south of the Sahel. The dry seasons can get very dry indeed, but that don't worry our antelope buddies none. Unlike camels, they can't directly store water in their body. They are, however, incredibly efficient at conserving water. Their feces is quite dry, their urine is highly concentrated urea, they can [change their core body temperature with the weather](https://pdfs.semanticscholar.org/8649/8f9c03409b5fcb1e4c19338a7e85b15ebc4c.pdf) and they are capable of getting their daily water requirements just from the plants they eat. In short, they'll be happy to lap up some liquid water but in a pinch they really don't need to as much as other animals, especially not horses or cattle.
Camels will make excellent long-distance transport animals or even draft animals. But alas, they're no horses. Yes, it's true that camel 'cavalry' has existed in various forms throughout history. But most of it has been in *response* to horses because of how much they hate camels. When used like cavalry, camels can be rather unwieldly in wartime situations. They're slower to accelerate, can't keep up their top speed for very long, and their high center of gravity will make sharp turns quite the prospect. It's also less convenient to swipe at people from way up there. Without the deterring, anti-horse quality, they're just big targets.
Both eland species, being antelope of course, are quite athletic, but giant elands are clearly the faster of the two with a top speed of 70 km/h to the common eland's 40. At least two pages from a [discount hunting agency](https://www.discountafricanhunts.com/africananimals/eland-lord-derby.html) and [another hunting website](https://huntforever.org/tag/record-book-giant-eland/) claims that they can run continuously for hours, but due to the lack of clarification I'm going to assume at least some of that distance is a half-speed trot. Both species can jump several feet over vertical obstacles.
Both species, while still wild animals, can easily acclimate to human presence. They are bred in captivity, with common eland being the popular choice for farming for meat and milk.[](https://i.stack.imgur.com/OO0Gs.jpg)
You could probably pick either of these species. For speed, I'm not sure how extensively this has been researched; the data for common elands could come from very few observations, for example. I'd personally go for the giant eland anyway based on what we do know, and though they don't form herds quite as large I don't think it's much of an issue. Size-wise, *T. oryx* bulls weigh up to 942 kg versus *T. derbianus*' 1000 kg, which isn't much of a difference and both are quite hefty.
Being ruminants, elands will also be more effective at digesting plant material than horses. They consequently require less food, and elands themselves are capable of both grazing and browsing a wider range of plants than horses or cattle are used to.
Exotic mounts like these can really spice up a world.
[](https://i.stack.imgur.com/N9yW9.png)
(Credit: [What If We Had Never Domesticated The Horse?](http://www.strangebio.com/post/84701663074/what-if-we-had-never-domesticated-the-horse)
[Answer]
Remember that a horse is a camel designed by a committee with all the flaws of being an imperfect camel. Horses are just cheap imitations of camels.
Elephants can live in very dry climates. Since every elephant needs to drink a lot of water every day, an army or caravan using elephants would have to carefully plan its march to always be able to camp at waterholes and to carry along enough food for the elephants in really arid places.
Mules are also superior to horses in many respects so possibly your people might breed mules.
It is always possible that a trading caravan or army might contain several different species of transportation and riding animals, such as horses, Bactrian camels, dromedary camels, elephants, rhinos, mules, horse-zebra hybrids, cattle, bison, large goats, dogs, etc., using different species for different purposes for the most efficient operation.
[Answer]
# Camels
I've ridden camels in North Africa, the Gulf, and savanna regions of central Asia. They're taller and faster than horses and can rival for endurance. Keeping them cataphract (completely enclosed), and training them to suit your purposes, you may find the gods jealous of your camels.
[](https://i.stack.imgur.com/pV6Jo.jpg)
(can't find a credit for this picture - source google image search)
From this Herodian IV.14.3, *Meanwhile Artabanus was upon them with his vast and powerful army composed of many cavalry and an enormous number of archers and armoured riders (kataphraktous), who fought from the backs of camels with long spears, avoiding close combat.*
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[Question]
[
The trolls in my story have a very thick and nigh impenetrable skin. In the time before guns, you would need a very sharp high-grade steel blade to breach the skin and, even then, after a few hits, the blade would be dulled significantly.
The trolls are very thick-skinned and the skin resembles a stone like material like thick callouses. It is covered in layers of moss and lichen. The trolls are turned to stone during the day and they don't really care about how clean they are.
The trolls will be roughly 4-5 meters high (10-13 feet)
I did some [research](https://www.academia.edu/7823775/Impact_Analysis_of_Medieval_Weaponry) and the breaking point of a claymore is 2624 newtons.
A 9mm bullet weighs 7.45 grams and will travel roughly at 310 meters per second.
Then 0.00745 kg \* 310m/s gives us an impact force of 358 ish newtons.
A [baseball hitter](https://hypertextbook.com/facts/2000/AlbertKlyachko.shtml) can hit hit a baseball with much greater forces than the breaking point of a claymore.
So let's put a guess at penetration at roughly 2200 newtons needed with a sharp edge.
So a sword seems a lot more effective than a 9mm gunshot. Would a skin that can withstand ordinary sword slash and jab attacks from a skilled swordsman be able to resist bullets from modern day firearms? My basic lookups seem to indicate so. If so, what caliber would be needed for penetration?
[Answer]
Your trolls seem to be made similar to rhinoceros or elephant skin. Normal ordinance (like small caliber ammo) have usually poor penetration against these (they can cause bleeding but won't penetrate), but there is ammo designed specifically to hunt big pieces that will penetrate the skin and usually with terrible effects (as the skin is so thick, the bullets tend to tumble and/or break, causing horrible internal wounds).
And if your trolls have a skin thick enough to surpass the elephant...
[](https://i.stack.imgur.com/OI4sl.jpg)
*Big guns for big problems* present the Denel NTW-20 antimaterial rifle. With a weight of more than 30kg it is not exactly portable but can shoot bullets up to 20mm diameter x 110mm length with a force of 40kJ at a distance of 1.8km. This is made to penetrate walls and lightly armored vehicles (that's why it's called anti-material). We guarantee no troll will withstand a well placed shot or we give your money back.
**EDIT:** As I've seen in your clarifications that the idea is early defense in case trolls that we haven't seen for 1000 years awake suddenly, my guess is that not everyone has or can afford an Anti-Material rifle. So, as an early (and let's be honest, more practical) defense...
[](https://i.stack.imgur.com/orQIu.png)
*All the Game* introduces the CZ-550 big game hunting gun. Chambered with a .375 magnum H&H that produces up to 6kJ of force, this gun manages to penetrate the skin of the biggest game while retaining a manageable recoil at a reasonable distance (it retains good accuracy up to 800m, although usually is shot between 300 and 500). It is also you can find in almost every major city of the planet (although not in great quantities), even in gun-regulated Europe (that frowns on anything remotely militar, but loves big bucks customers that love hunting). Buy it today and we will throw a sample of our new jacketed "no expansion" cartridge!
[Answer]
While Stormbolter gave a concise and effective answer to your question, I'd like to add some things for you to think about.
What I'm guessing from your question is humans started fighting trolls using swords. But even this method, while it manages to pierce the troll skin is: a) costly, since it dulls the sword extremely fast, b) probably dangerous.
Hence, humans may or may not improve firearms technology and you're wondering if it would be effective and worth the time for them (again, this is purely a guess).
I'm no military historian, but I believe cannon predate smaller firearms (Edit: by about a hundred years in Europe. We indeed saw the appeal of handheld cannon pretty quickly), simply because they're easier to conceive. Miniaturizing something is no trivial task, much so if you're still figuring how to properly contain the detonation/deflagration of the powder.
From an evolutionnary point of view, humans would have first developped big cannons which would be **extremely** effective against pretty much anything, as long as they touch.
But let's say your magical creature is somehow impervious to cannonball. Even if your munition does not pierce the troll hide, the mere resulting shock will turns its innard to pulp, and most living organisms end up pretty much dead when that happens.
You would probably observe tactics such as seen in history, with artillery thinning the ennemy lines, before the infantry engage in the dirty work. Since each shot can probably kill a troll on the spot (once again, as long as it touch), humans will work to improve the technology, and eventually come to big hunting rifle.
The last paragraph is of course only pertinent if trolls band up in large groups to attack humans. But defending settlement from troll attack would still be a lot easier if you can shoot the thing before it even become remotely menacing. And then, you follow the same path as explained before, and you have boomsticks to deal with trolls.
**Edit:** Given your comment, troll as a menace that has "awoken" from the past, it boils down to what people said. Small caliber, unlikely to pierce. Special ammo, depends. Bigger guns will surely put a hole in your trolls though. Local forces may been variably equipped, but even small police department in my country have at least one shotgun or a SMG lying around. Not much to fight a full scale invasion, probably enough to repel a single troll until army get there.
[Answer]
**Sandbag penetration** should be roughly equivalent to what you need. Your description of the hides, "a stone like material" and "turned to stone during the day" sounds to me like something made of "rock" just not in a solid slab (sand), held together by something flexible (bag) to allow some movement ... a [Sandbag](https://en.wikipedia.org/wiki/Sandbag#Fortification) skin.
It should take very little research in to the military applications of sandbags as defense to find out just how thick you want the skin to be to get the type of defense your Trolls would need or have.
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The world is Earth, probably west coast of the USA, in the throes of severe climate disaster; major storms, earthquakes, droughts, fires and floods are the norm.
I am looking for a way to suddenly alter the geographical landscape so that a natural border that keeps people out suddenly becomes *easily* permeable to a few. I imagined the following: a mountain splits (like a log being split) due to an earthquake, thus creating a pass where none existed before, but I'm not sure if that's actually possible. Is it? Open to other suggestions as well! Thank you.
[Answer]
**Megaflood from melting ice dam.**
<https://io9.gizmodo.com/5940112/ancient-flood-myths-may-have-a-basis-in-geological-history>
>
> 10,000 years ago, at a time when humans recorded historical events by
> telling mythical stories that got passed from one generation to the
> next, huge parts of the North American continent were deluged by
> massive walls of water. They were, as geologist David R. Montgomery
> writes in this month's Discover magazine, "Biblical-type floods." Huge
> regions of the Pacific Northwest, called the "scablands" were chewed
> up by flash floods that were more like tsunamis. And it was all caused
> by the melting of the glaciers from the last ice age. As the walls of
> ice damming lakes melted away, the waters would rush out across the
> land.
>
>
>
Here is a video depicting the changes that happened in one such flood in the U.S., the Missoula Flood. <https://www.youtube.com/watch?v=G_LRo3wIT34>
Big things happened fast when the ice dams gave way. Large lakes suddenly drained. Large areas of dry land were suddenly washed away or carved into canyons by fast moving waters. I have seen it suggested that the Hudson River valley was carved in a matter of weeks. Areas that were previously dry could become covered with new lakes.
Your impassable area (a treacherous canyon, or impassable Hawaiian style lava fields? Or pricker bushes! Or stuff from [this question](https://worldbuilding.stackexchange.com/questions/81077/a-realistic-option-for-enclosing-a-geographic-area)) could be washed away when the ice dam broke, or covered with water you could canoe across. Or a lake impassable because of lake monsters might suddenly drain dry.
Resist the temptation to poke the stranded monsters with a stick as you walk by them.
[Answer]
**Drought.**
Basing this on your explanatory comment:
>
> Most roads have been destroyed (mudslides, earthquakes, floods), cars
> are a thing of the past, water is scarce.
>
>
>
Drought will lower the level of lakes and rivers. While the levels won't change super quickly, they still have tides (larger lakes have their own tides and rivers connected to the ocean sometimes do). So levels go up and down during the day.
Sometimes a very small change in water depth can make a big change to the surrounding land. It might only take 1-2 inches of change to turn a lake or sea surrounded by impassable cliffs into water surrounded by a pathway alongside impassible cliffs.
[](https://i.stack.imgur.com/ifdBk.png)
[](https://i.stack.imgur.com/JgRsU.png)
[Answer]
## Ice
If the place is a huge lake or even an ocean, people could wait until the thick of winter to cross. By then, the low temperatures should have frozen the water surface hard enough for people to cross.
I'm gonna fail to quote the exact historic event here, but I remember seeing some hyphotesis that stated that people crossed continents like this (Europe to North America if I'm not mistaken) during a very harsh winter (this is just a theory though).
## Tides
Depending on the place, low tides can reveal quite a lot of walking ground. Of course tides change rapidly, so people would both have to move fast and have specific places to wait out while the water is too high, but it's doable.
Maybe your story could have this rocky, seemingly endless, coastline where people would walk in low tides and hide in caves while the water's too high.
## Erosion
This is natural phenomenon that manages to cause quite the damage to what appears to be rock solid foundations. Maybe years and years of erosion could end up eating what was once a great natural barrier. Maybe it's not completely gone, but it's damaged enough to enable people to cross it.
## Flood
If your scenario is canyon-like, a flood of biblic proportions could turn it into a huge lake. Yeah, I realize how ludicrous this is - It sounded awesome so I said it. You could also use the opposite of this (the drought), which was mentioned by Cyn in his answer.
## Fire
I don't really see a forest as an obstacle, since you can push through a forest even if it's very dense (if you have the right gear, that is). But if your forest is dangerous (maybe inhabited by crazy perilous wild animals) this could be an answer. No forest, no problem.
I also thought about a vulcanic eruption, since lava turns solid in touch with water. I can't think of a specific situation where this would apply, but you have my permission to go nuts with this, if you want to.
[Answer]
To begin with, it seems that you are postulating a non-technological society. After all, in our own (very much technological) there simply aren't any barriers we can't cross, right?
So, with a much less capable society in mind, I suggest you read the Engineer trilogy (starting with "Devices and Desires") by K.J. Parker. He provides two countries separated by an untrackable desert, which effectively is uncrossable. It's not *actually* uncrossable, of course, but the effort required to find a crossing is so great that nobody manages it. Uncharted deserts are inhospitable, and with no direct motivation no one has found the way.
It turns out, though, that an underground river does cross the desert, and for a week in spring the water table gets high enough to allow a certain desert flower to bloom. During this brief window of time it is possible to follow the course of the river and establish a path through the desert, although you can specify that the desert is broad enough that it takes several years to do the job, one week at a time. Once the path is known, it's simply a matter of carrying enough water to survive the passage. So long as knowledge of the path is kept secret, the few possessors of the secret can readily cross the uncrossable desert.
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[Question]
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In its heyday Earth was a great interplanetary trading post on account of its low gravity moon which was used as a warehouse for all kinds of goods.
The Moon was covered almost entirely in large warehouses and each had a staff of thousands. These people were manual workers, management and administrators plus technicians to maintain living conditions. All the people you would expect for a large business. None of them were research scientists although there were a few engineers.
Sadly Earth was hit by an asteroid causing extinction of all non-aquatic animal life. Many edible plants and sea-creatures survived.
Even more sadly, this coincided with a slump in the galactic economy. Trade died and no-one came their way any more - not even pirates who have no access to FTL travel.
Can they ever escape from the Moon back to Earth?
**Resources**
1. They have whatever minerals etc. already exist on the Moon (as known in 2018).
2. They have their buildings and equipment which are made of 2018-level technology and materials.
3. They have a vast quantity of goods in the warehouses.
4. These goods consist of (and only of) anything that could be bought on Amazon in 2018. But they don't have to buy it - it's already in their warehouses.
5. They have all home comforts for family life including fresh fruit and vegetables grown locally.
**Unavailable resources**
1. There are no petroleum deposits on the Moon as life had never existed there before the advent of humans.
2. They don't have any kind of space ship. They relied entirely on a now defunct shuttle service to get from Earth and back assuming they wanted to.
3. There was limited farming of animals because of the difficulty in growing sufficient quantities of foodstuffs. Meat is a luxury and most pets were banned as a consequence.
**Question**
So - can they ever escape from the Moon to Earth and land safely? If not can they survive indefinitely on the Moon as a community?
[Answer]
# Nope
Mainly because:
>
> These goods consist of (and only of) anything that could be bought on Amazon in 2018. But they don't have to buy it - it's already in their warehouses.
>
>
>
I just did a few searches in amazon.com, amazon.ca and amazon.co.uk. unfortunately they don't seem to sell hydrogen in any form and amount that you could use for rockets. They don't even sell RCS systems like the Appolo program lunar modules ascent stage used, nor RCS propellants like Aerozine 50 and nitrogen tetroxide.
Without scientists, and with a limited amount of supplies and people for throughout testing, I don't think you could emulate a space program, nor do a desperate attempt to jury rig a few toys into a proper ship to Earth.
As for living indefinitwly on the Moon - I think a regular shuttle service from Earth means that you'd get your food from there.
The moon might have had the odd hippie growing their own food in their quarters, but large scale farming on the Moon is not something you would do. Not when it lacks a natural atmosphere and rich soil for the plants, while having those things in abundance on Earth, which is just a few hours away.
Even if those guys are on full survival mode... Andy Weir's *The Martian* had a lot of handwaving, and that was just one person involved. You can't feed a whole population on improvised farming. That would be a nutrition nightmare.
[Answer]
Forgetting for a moment all about the resources they do and don't have if the population are primarily moon-born return isn't an option. Anyone born on the Moon almost certainly *can't* go to Earth and definitely doesn't want to. Its a matter of gravity, humans who spend time in low gravity lose bone density, fast, people born in 17% Earth gravity are going to be exceedingly delicate, they wouldn't survive re-entry and their skeletons would collapse under full Earth Gravity if they did. If you wanted to recolonise Earth you'd need something like an [O'Neill Cylinder](https://en.wikipedia.org/wiki/O%27Neill_cylinder) first in which to breed a gravity adjusted population.
[Answer]
You can buy packs of sugar, cardboard tubing and baking soda on amazon, you can make a solid booster rocket from those ingredients. Nothing fancy but enough to get into orbit from the moon… with a ton of luck.
This would be more a 'lets get help' solution, since i doubt the hundreds of thousands of people all have half a ton of sugar available.
Although… they have farms, maybe they can grow it? Id scale down the amount of people needed to staff the facilities tbh.
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Writing about suspended cities within a planet's atmosphere! The story itself focuses on the air forces that fight for each of the hundreds of floating city states living in the sky, but that's here nor there. I would prefer the suspended land masses to be naturally occurring (predating technology).
I've come up with some options for how it would work, but I could use some help with looking in depth at each possible explanation for how the cities fly.
1. Asteroid Lodestones - this is my favorite theory, as it has naturally occurring floating-land that has been around for millennia in this world. The theory is that over time, space rock crashes into a planet as it does with any planet. But these asteroids are naturally magnetized to be repulsed from the planet's surface. Therefore, the asteroids enter the atmosphere and get hung in the sky before impacting. Or after impacting. Either way, this allows for floating land without technological help.
2. Magically powerful atmosphere - Piggybacking off theory number one, if the asteroids weren't NATURALLY magnetized to repel from the planet's surface, could the space rock by magnetized as it passed through a planet's atmosphere? Could, theoretically, the magnetic waves be that powerful in the upper layers of an atmosphere? And could something be magnetized in such a violent, intense way?
3. Electromagnetism (maglev) - I have a rough understanding of this. Electric currents are needed to produce a magnetic charge, which keeps things afloat? Do the rocks themselves have to carry the current? If not, is there a separate magnet which has to conduct electricity, such as a tower or surface-based giant magnet? Similar to theory two, could an asteroid by electromagnetically charged when entering an atmosphere?
If you guys could give me feedback on these, any tweaks to these theories, and any other ideas about floating land masses I would be very grateful!
[Answer]
Magnetic field of a planet will not hold a city up. Even if it is strong enough, it can hold cities only at the two magnetic poles. Such city will need lots of magnets strategically placed and correctly oriented in its foundations, so it is unlikely to arise naturally.
You can have city in any spot if you have similar magnets placed in the ground below it. You cannot have entire planet magnetized. You really should read up on magnets, their north and south poles, and magnetic field lines.
You cannot magnetize atmosphere, and magnetic field that is off-planet and strong enough to hold up a city will make all iron fly into the sky.
If you want cities to be mobile, use dense atmosphere and balloons. Zeppelins were pretty robust when in the air, most of the crashes happened during landings.
If you want natural, have plants that grow air bubbles filled with methane or helium (harvested from underground sources). I know kelp has such bubbles (but underwater). Or you can natural gases making foam out of lava. Once foam solidifies, and if solid labs is separated from it, it will float in the air.
**Edit: in response to OP's comments**
You really needs to learn more magnetic field and how has a direction.
Magnetic repulsion can only happen between two magnets, and only if they are lined up just right. Moreover, if magnets are simple shapes like balls, they will push each other away from that perfect alignment. You can try it with any two small magnets, and it will work like that with magnetic field of a planet.
To get stable leviation with magnets, you need special shape of lower magnets (or multiple magnets)
E.g. this: <http://web.mit.edu/viz/levitron/Physics.html>
Or more recent superconducting hovering skateboard (which can only hover over magnetic carpet).
Levitating above a magnetic pole will require very special arrangement of permanent magnets in the floating city, since planet is a ball magnet, not a ring like in levitron above.
Magnetic field of a planet cannot magnetize an asteroid to achieve the right shape of magnetic field. Moreover, such induced magnetic field is short-lived, and levitating above the pole will quickly re-magnetize the asteroid to be attracted to the pole.
You can have ancient/alien race construct the floating city with strong permanent magnets.
Or you can just hand-wave some rocks with negative gravity (like in Spielberg's Avatar movie).
[Answer]
My first bit of advice would be to drop the idea of magnets or anything magnetic as being the mechanism. To have it occur "naturally" would involve too many contortions of planetary mechanics and using maglev would be impractical as well - the inverse square law would mean that having an altitude of more than a few centimetres would require so much energy as to be ludicrous.
What I propose instead would be to have the lower regions of the atmosphere be a "soup" of very dense gases and your cities based on asteroids made up of a materiel that is *less* dense that, as a result floats on the denser atmospheric layers beneath.
This way you could still have:
* naturally occurring landmasses that "fly"
* a planetary surface beneath (you'd need a pretty pressure-resistant craft to reach it mind you - but not much beyond a submarine)
[Answer]
**Kite city.**
[](https://i.stack.imgur.com/eNoKd.jpg)
<https://www.artstation.com/artwork/nY1bO>
Your city does not float. It soars. Your world is one with phenomenal updrafts and thermals. Huge, fragile cities kite above the surface. The city kite pilots work in shifts and their job is crucial - watch the clouds and the weather and keep the city afly. They have spinnakers and accessory kites they can deploy, and the great kite cities can fold in surprising ways - the citizenry react to these movements without breaking stride. Large cities can have defensive capabilities like dreadnoughts. Smaller cities converge on large vehicles. There is a spectrum from large to small, all kiting their way as the air takes them.
[Answer]
**Realistic Gravity Manipulation**
So, there is a certain level of handwavium element to the execution of this idea, but the physics are kind of solid. Gravitoelectromagnetism. Doesn't have anything to do with electricity or magnets at all, but scientists are kinda jerks like that. Anyways, it was discovered a few years ago by Gravity Probe B that large rotational masses actually cause an effect called frame dragging, whereby space and time are kind of drug along and slightly twisted with the large rotational mass. It was discovered (at least on paper) that two of these rotational masses rotating in different directions could possibly cause some repulsive effects somewhat similar in nature to the effects of electrical charges or magnetic fields repelling each other, except with space, time, and gravity instead.
So basically, in certain theoretical scenarios you can get gravitic fields to repel each other kinda like how magnets or electrical fields do. Also time and space has something to do with it. Its weird. I suck at math too. And physics.
Thing is, we're talking about two planetary masses, and the rotational rate to achieve cancellation has to be nearly relativistic right? So it's not exactly like we can just take two planets and spin them at a high percentage of the speed of light in opposite directions right? Well... kinda.
Take some extremely dense matter from a white dwarf and contain it in some sort of ring. Now you have something as massive as a planet, but just really really dense. Take two of these rings and accelerate the white dwarf matter inside of each ring in opposite directions to a percentage of the speed of light like a really big, really energy hungry particle accelerator.
Viola, opposing frame dragging effects begin. Now here is where things get really cool (Assuming the math is right). Anything sent through the center of these rings will be accelerated without experiencing any G forces. Its basically being pulled and pushed along at the same rate by opposing torsional fields of space and time and thus is in effect, no longer experiencing the effects of gravity. As long as the object sat in the sweet spot between these two cancelling fields it would in essence, just kind of sit there suspended. So you got one of these rings of hyper dense matter being accelerated at high speed below the city, and one somehow above it (in a geostationary orbit maybe?) and the city sits in the sweet spot between the two where gravity is no longer effecting it.
**Problems!**
**The math is wrong:** Somebody might have miscalculated some variables, or may have misinterpreted the findings and the entire theory turns out to be bunk. Frame dragging effects and their exact effects have yet to be accurately modeled and studied, it is believed that doing so would be incredibly difficult and until this is done all of this is still not considered to be confirmed science. The theory is relatively new and not very well studied yet.
**Even if Not, Still Waving Hands Pretty Hard:** Collecting mass that dense, containing it, then accelerating to relativistic speeds, then keeping it that way indefinitely requires a lot of energy. I illustrate the amount required vs what they are using it for in our terms, its like building a nuclear reactor just to run a single coffee maker. At minimum our race would have to have a Kardeshev 2 level ability to access and manipulate energy. (IE can harness 100% of the energy output of a star or its equivalent.) This level of technology is so unbelievably out of our reach that talking about specifically how they do it with our current level of development is basically waving our hands and grunting "magic." This phenomenon will most certainly never be found in nature or achieved by a pre-technological society. If you want to go that route you are just going to have to utilize the old "its just magic" explanation.
[](https://i.stack.imgur.com/8yYfc.jpg)
**People Dwelling in the City Don't Have Gravity Either** Pretty Self explanatory. The object in between these opposing fields do not experience gravity. Period. Nothing in the city is being effected by any gravitational fields outside of the area of nullification. At this point, you might as well just build an orbital city. I mean, maybe your Kardeshev 2 level society just really likes showing off and builds something impractical just because they can, Its been done before. Its just not a very practical way to do things. Maybe if we are really handwaving here the same fantastically advanced people somehow managed to make the field only effect the city, or found a way to counteract it within the confines of the city? In which case you are basically just saying "meh, its science." Then you just end up utilizing the same trope as the magic thing earlier.
[](https://i.stack.imgur.com/3Z25z.jpg)
**Summary**
Anti-gravity and gravity manipulation may very well be possible, at-least on a theoretical level, but not naturally. The idea that something naturally occurring or predating technological sources could achieve this with magnetic fields or something is bunk. The precisely balanced system of high energy effects required to make something like this happen simply doesn't occur naturally. So I have a proposal:
The great old ones trope. A Kardeshev 2 level society built all these floating cities a long, long time ago as a bunch of resorts or fancy ultra-technological space mansions or something. They all died, or ascended, or got bored and left or something a long long time ago too. Now a bunch of comparatively backwards people descended from their estate servant staff who got left behind live on these floating cities and islands with zero clue as to their origins or original purpose. They've just always been there and as such nobody considers that to be terribly odd or worth looking into. (Also the last time somebody got curios and went poking around they accidentally turned the gravity back on and everybody died so nobody does that anymore.)
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Not a great physics person, but I am taking astro and enjoying it, so here goes (consult with someone else who knows physics).
From our friend science (please correct me, but this is angular momentum no?) [](https://i.stack.imgur.com/fwc7X.png)
Anyway, basically what this means is that the orbit time is equal to 4π^2 (a constant) over another constant times the mass of the orbiter (city) + the orbitee (planet) times the distance between them cubed.
With all that out of the way, I feel like it would be possible if you just had the cities orbiting really low? I guess that means they're going slowly, but you'd just have to make sure that they aren't hitting escape velocity
[](https://i.stack.imgur.com/FkCHg.png) where M is the same M as the mass of the planet mentioned above, G is the same as G above, and R is the radius of the planet (I believe).
Here are some of the problems you'll have to deal with if you take this route:
* you'll need to have a very thin atmosphere (because the city will need to keep moving at the speed it is going and the atmosphere will probably cause lots of resistance/heat (I'd imagine)
* you could try to make the city and the planet have the same rotational speed as the orbit, so that basically from the ground it looks like the city is always directly ahead and the same part of the city always faces the moon (look up synchronous rotation, it's why we always see the same side of the moon).
* if the cities speed up, they will need to be careful because they could hit the exit velocity and get ejected into space (which is kind of a fun thing to have to worry about in a story).
Anyway, some of the science in this post is probably wrong, but I enjoyed writing it and you might be able to pull some ideas out.
Oh, one more thing. You could try doing it space elevator style (esp. if what I recall is correct). You could launch something beyond orbit, but have it tethered to the planet (the big problem on earth is we don't have the material to do it, but that's easy to fix) and then basically it just swings with the earth's rotation. I'd do more research into this if that's what you're thinking of.
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You'll be needing a bullshit explanation for this so lets get a bullshit explanation. Keeping even a few tons on the air is going to take nuclear bombs worth of energy daily, building the entire city out of magnets isnt going to give enough lift for your purposes.
So heres the bullshit I came up with: somebody, perhaps your own people or perhaps aliens who moved on beyond our reality, created matter with negative mass for all manner of purposes such as space travel. To make it easier to handle they gave the material attraction to itself similar to how water attracts itself, as negative mass would push itself away otherwise. Much of the waste coalesced and a bunch soaked into the ground on your planet. This reduced the mass of all the material it soaked into and make it into a lower than air mass, allowing it to float.
Advantage is that anything that soaked the negative mass can float without any special circumstances in the atmosphere or ground needed to remain airborne. And the negative mass could be used in some aircraft for example.
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There's several reasons why floating sky cities don't make sense.
1. Energy consumption keeping them airborne: Assuming that's magic, or irrelevant.
2. Land area, making city population reside in modest surface area
Real reason is what altitude can human anatomy exist safely.
Anyone who watched BBC series top gear; at high altitudes above 10,000 feet atmosphere is too thin to safely breathe. In a car challenge, the hosts [attained](https://www.youtube.com/watch?v=NOcJOn0nxnU) a driven altitude of 17200 feet before giving up and going back; with oxygen levels as low 8%.
It's COLD. Atmosphere; ambient air temperatures drop 1 degree Fahrenheit every 650 Feet in elevation. Even at 70 degrees mild spring temps on ground level, at 10,000 feet, the temperature is 34 degrees. Just shy freezing. At 15,000 feet, it's below freezing.
At an altitude
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and any other ideas about floating landmasses I would be very grateful!
->I've loved floating castles/cities ever since seeing the cover of the old DND Dungeon Masters guide. There are many ways to answer this. Do you want to have the floating cities be a major part of the story & world? So for example, the cities constantly need to acquire resources. That might lean towards having cities land or dock at certain places to buy/trade or excavate the resources they need before going aloft again. This could provide a great way to bring characters to different parts of the world setting as well as travel to different world environments and peoples.
A permanent solution could be anti-gravity (tech) powered by anti-matter reactors or air elementals bound into the object. An entire tribe or nation of magic casters could be enslaved that power the device/city to fly. The options are near endless. You could have a space structure from which the city is suspended. The city could 'float' because it travels/flickers in and out of another dimension. Or maybe just pocket dimension bubbles that somehow got connected to this world, are floating around and somebody figured out that you can access them and actually live and build there.
Using something like anti-matter engines (kinda like the flux-capacitor in Back to the Future) you can generate enough power to do almost anything including powering enough low tech 'engines' to make just about anything fly. I mentioned anti-matter engine but really it could be anything you want to make up. It could be the De-Gauss Nuclear Repulsor Generator(s).
Here's another idea. Mining the 'ice' rings around the planet for your 'magic' levitation mineral.
Or if it's a 1 off, it could be from some hi-tech war or technological experimental accident that caused some sort of chunk to float.
Maybe even flying mechs or creatures that rotate duty to hold the city aloft.
Check out movie Appleseed Alpha. It's a huge walking mech. Could easily be transformed into a city. Ok, that should give you something to think about.
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This is sort of a vague question, and I do not have a specific setting in mind. However, if you had a society whose members were immortal, how would you ensure that the leadership was dynamic and efficient? Do you have mandatory term limits, and replace a certain part of the leadership every year? If so, how would you implement it? The officeholders would probably resist giving up their power, due to both greed and because they would probably see the new bureaucrats as stupid and inexperienced. Would you have the old officeholders and new office-seekers compete freely? If so, few young people would get into positions of power, as the old guard would be more experienced and would be able to use the accumulated influence and experience of eons to keep their posts. Also, getting rid of the old would be disruptive to the functioning of government, as they know how to run society smoothly, but not rotating them might result in stagnation, as they hold fast to old ways and reject progress.
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Good leadership is a quality that we find elusive even now, after millennia of trying, in part because we all have a different view of what 'good' leadership is.
Is it the ability to choose to do what's best for the nation?
Is it the ability to get things done, no matter the cost?
Is it the ability to compete with neighbouring nations?
Is it the ability to preserve the cultural heritage / religion of the nation?
Is it the ability to conquer one's neighbours and assimilate them?
To be frank, I'm not sure what good leadership is and none of the people I respect have any idea either. There are only two things that all my friends and I agree on;
1) None of us want to be leaders as the responsibility is too much
2) There's no way we'd trust anyone seeking leadership with the position if it was up to us.
All this having been said, the answer to your question largely relies on defining what good leadership is to you.
If it's strength, then leadership would be a contested position, probably via a fight to the death in an arena. An 'election' (and I use the term loosely) would be an event between two candidates that you sell tickets to, and both candidates (probably an incumbent and a challenger) fight for the right to lead. The strongest is the one who's still alive when the other isn't, and then takes on the role.
If it's sacrifice, you have a mechanism where leadership is paid for through the removal of one's immortality. In other words, you can live forever as a subject, or you can live a normal lifespan as a leader. This would have the added advantage of ensuring renewal in the role on a regular interval.
If it's the willingness to give back to the people, then you offer leadership as a calling rather than a job. You can only become leader if you give up all personal belongings and live on the goodwill of the people. You get no wage, you get no house, no palace, no warm blankets as part of the job. You only get clothes, food, blankets, shelter from those willing to contribute to your wellbeing. If they're having a bad year and have nothing to offer, then your year is going to be a lot worse.
If it's command, you can only become leader through the military chain of command. You must start at the base rank, and work your way through the ranks until you reach a flag rank, at which point there is a regular general election among the officers as to who from flag rank should be the leader for the next period, and you're now eligible for election.
If it's scientific prowess, you might make a person's candidacy for leadership contingent on the number of papers they publish on a given topic, or the number of times they are referenced in the papers of others. As someone gets more references (because they are writing more relevant work) they get the leadership.
Ultimately, the answer comes down to what you think are good and bad ideas, and what you mean by renewal. Things like economic policy have to change with the reality of resource availability, innovation and international diplomacy. On the other hand, the basic tenets of the criminal code (murder, theft, assault, etc.) have been in societies for a very long time because they work.
The important thing here is that you know what's important to your nation and the health and prosperity of its people. If you know that, then you design your leadership selection process around that and you're good. If the selection process emphasises what you want your leader to do, then it's far more likely that you'll get the leader you need (but not always the leader you want).
This last point is perhaps one of the most important, and one of the chief failings of democracy as a selection process. The leader of a nation HAS to have the best interest of the nation at heart, not necessarily the best interest of its people (especially as individuals) at heart. Democracies struggle with this because sometimes necessary reforms are deeply unpopular, and therefore those suggesting them are never given leadership. Often the reason why it was necessary is only evident to most of the populace with hindsight. Whatever your selection process, retaining the faith of the people in the *office* if not the *officer* is paramount.
This usually means a good education system and the ability to explain policy choices to people in a way they can all understand. This is a lot easier said than done, which is why I wouldn't make a great leader and I know it. That said, there's a lot of poor leaders out there who think they're spectacular at it. The real trick, regardless of your final selection process, is weeding out the latter.
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**Are you sure there'd be much of a government?**
The single biggest problem with immortals is that you must strictly limit (if not outright prohibit) progeny — otherwise in very little time you have a planet-sized population. Let's assume you don't have this problem for whatever reason. What this means is...
* No babies
* No children
* No teens
* No schools in the traditional sense
* No driver training
* No geriatrics
* No minor healthcare
* No welfare (as we understand it)
It literally means that a proverbial 50% of the reasons government exists ... don't exist. But what's really odd is...
**It appears you're applying mortal behaviors to immortal people**
Which isn't all that uncommon. You'd be surprised how often people make god in their own image. I found it curious when you said, "officeholders would probably resist giving up their power, due to both greed and because they would probably see the new bureaucrats as stupid and inexperienced." Except the newcomers are immortal... which has the effect of evening out inteligence and experience over the millennia such that nobody is particularly better at anything than anybody else.
Let me give you an example: I'm in my 50s. It's actually difficult for children to sneak up behind me and startle me by screaming, "boo!" Why? Because I've experienced the moment so many times that even when I'm not prepared to experience it again, my brain simply reacts with a yawn. I don't see the world like 10-year-olds do (who still see most of the world as something they've never experienced... something new).
Now imagine a whole culture of people who have lived thousands of years, experienced basically everything thousands of times over, who have become educated in scores of careers, lived those careers, and become bored with those careers. People who very frequently never think through what to do next — they simply react to it based on what an unfathomable amount of time has taught them to do.
* Relevant movie/TV quote #1: *Groundhog Day,* "Maybe God has just been around a long time and knows everything."
* Relevant movie/TV quote #2: *Agents of Shield,* "That's why you'll practice it over and over until you've got it down cold. Muscle memory. Don't think about the action; let the action help you think."
* Relevant movie/TV quote #3: *Star Trek: Voyager,* after hearing no dialogue in the Q-continuum... "Because it has all been said. Everyone has heard everything, seen everything; they haven't had to speak to each other in ten millennia. There's nothing left to say."
**I'd be surprised if much government was needed at all**
What does it mean to be in charge? From the base-human perspective, it means having the power to do what you want, when you want. From the somewhat more enlightened perspective, it means meeting your population's needs for safety, residency, productivity, education, and entertainment.
Honestly, the base-human need is the funniest to think about. A bunch of immortals (gods, perhaps without the convenient thunderbolts) are all listening to some bragart trying to impress them with his/her strength, mental accuity, whatever — and yawning after they've been momentarily amused. They've seen it all before, know perfectly well how to rid themselves of the nuisance, and move on with their daily lives.
Because the base-human leader needs to foce the population to his/her demands, and that requires power. In small communities, this can be achieved by your own sword arm. In bigger communities it requires sycophants/devotees/zealots/followers. It helps to have a military dedicated to the ideology that happens to reflect your personal tastes for power. They think they're supporting the nation. But remember — *immortals* — they've seen it all before, know who you are (*really well!*), and are a whole lot less likely to be convinced to simply follow Simeon (you know, "Simeon Says...") when he/she proves to be a megalomaniac.
* Relevant movie/TV quote #4: *Star Trek: Voyager,* "Oh, we've all done the scarecrow. Big deal."
*By the way, that ST:VOY episode is "Death Wish." You should go watch it. Watch it so many times that you can quote it without thinking. Then you'll understand why your statement about newcomers being stupid and inexperienced was so odd to read....*
**The more interesting government is one who meets everyone's needs, but what needs do immortals have?**
Not education, they can supply that for any junior member quite readily. In fact, rather than K-12+college schools, all you'd have are research centers, and all too likely personal research centers where a few like-minded individuals gather to hash out stuff I can't even imagine thinking about.
Not welfare, if they're still alive after a couple of millennia then they've worked out how to feed/clothe/house themselves without dependency on the government. Perhaps there's no greater crime than living thousands of years and STILL being unproductive.
Not a lot of things. What would be the point of incarcerating people for eons? Capital punishment would be the only thing that meant anything to immortals, so your judicial system becomes very simple. Mind your manners or we take your head.
* Relevant Movie/TV Quote #5: *Highlander,* "Each man's thoughts and dreams are yours to know. You have power beyond imagination. Use it well my friend. Don't lose your head."
**In the end, what leadership would be necessary would be driven by the all-too-predictable actions of the inferior mortal races**
You really don't need much of anything other than an oversight committee to make sure there's water in the pipes and a general to rally the troops when the Morlocks and Vogons come marching. (Yes, this is a bit simplistic, but you know what I mean....)
*What most people don't realize is that, unless things in Heaven are very different than here, immortality would be unbelievably boring. How long can you play ~~Halo 4~~ a harp, really?*
It might be the most egalitarian society on the planet, because everybody really is equal. Only in the most dramatic cases will one intellect outstrip all others, and so forth for all other skills/talents. But why would such people strive for leadership when there are so many competent people to do the boring stuff?
* Relevant movie/TV quote #6: *Flash Gordon,* "Ah, well, who wants to live forever? HAHAHAHAH! DIIIIIIIIIIIIIIIIIVE!!"
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In an immortal society everybody would sooner or later have a chance to be part of the government. Therefore, members of any government could be chosen at random from the population. They would serve for a certain number of terms, then leave government. This would continue until everybody else had their chance to be in government.
Please note this system describes appointing people to government. Leadership is always more difficult. Leaders would have to be chosen from among members of the government. Essentially this is based on a parliamentary system of governance.
With a random selection process to chose government, there will need to be mechanisms for some people to opt out on either a voluntary or compulsory basis. There will be many who never want to be in a government. There will also be people who should never be allowed to govern. For example, persons with authoritarian personalities. That way dictatorship lies, so it should be avoided.
Also, persons who have been in government and prove themselves manifestly incompetent at running a society at whatever level they held. These types of persons will need to be identified and proscribed from government.
On the converse is also true. There will be some persons who are exemplary in government. However, they should be kept in office forever. It would be better if there was a sufficiently large body of persons competent at government who would be prime candidates for selection. A slight bias in favour of their selection to ensure there is always a core body of them in any government.
There is every practical reason that the government of an immortal society should be a unitary entity. There can be many tiers of government, each with their own periods of office. Plus there will need to be a public service, probably, public services plural, to support the arms of government. By having overlapping periods of office and tiers of governments and public services will allow continuity and stability of governance.
Since being part of the government there will be a civic duty and responsibility of all immortal citizens, there can be high levels of education and training in all areas of government, leadership and public administration. Also, the members of an immortal society will all have opportunities to fill every level of governance and administration. From garbage collector, parking ticket inspector, being Lord Mayor, clerical duties, planning committees, and upwards to the premiership of their nation.
The random selection process will prevent cliques and cabals forming within governments. It will also block corruption of officials and members of their parliaments.
In conclusion, leadership is nebulous concept, therefore, this answer has concentrated on sketching a form of government where all citizens can participate in its running and at every level of governance and administration. The random selection of citizens into government positions will ensure maximum experience and knowledge of all levels of government.
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The following assumes that the discovery of immortality happens in free market post-modern society in which we live now. In this settings, the leaders don't lead in a way to define values, the good and bad, the way of living. Since the end of Cold War ideology has negative connotations. Instead, MONEY drives everything, allows WILL TO POWER to rule all values: the stronger apply their power onto weaker and the leaders are no exception. Today, the constant grow of consumption and waste became the true religion and as a such, it is the main tool for world leaders (the oligarchs) to manage others including politicians. I think that the immortality would change this, but it depends on the type of immortality. I would consider three classes of it:
* A: **Immortality as cure of death by age** people still could be killed and can die by disease, could went paraplegic, could kill themselves. Eventually some kind of death would happen, so there would be something like statistical lifespan.
* B: **Immortality as a perfect body** could involve many improvements like perfect regeneration (to fix limbs or eyes lose, heart attacks, cancer, maybe even death by gun or fall), perfect immunity (no diseases), perfect resistance (to avoid death by radiation, explosion, too high or low temperatures, vacuum). The chance of death by unfortunate circumstances would be lowered, but end of life could happen with some effort.
* C: **Immortality as a consciousness preservation or as a life backup** by means that death would be impossible.
## Price of immortality as a tool to manage ("lead") others
A: It would be more expensive than space travel. The price could resemble 50 years mortgage affordable only by high society people. Leaders would be more powerful, but eventually they would die. Power shifts in society would be less often.
B: The risk of dying would be much lower, so the price could grow much higher: if high society people needed to sign a contract to pay all their money for 1000 years, it still would be too cheap. The slavery period would probably be shorter at the dawn of the technology since nobody is planning that long, but later when immortal merchants were selling it, it might constantly grow to 50.000 years and beyond (it is still worth it). The leaders would find a business model to enslave others, the hope for eternal life (supported by market) would be a new opium of humanity and used to replace religion.
C: There could be no price tag for this since the advantage has infinite potential. It would be obtainable probably only by power. The very few most powerful people at the dawn of the technology would ensure that nobody else would get into the club, so the cake of power is not divided anymore.
## Effects on society and immortal "leaders"
A: Jails would lost their meaning, other punishments (death penalty, slavery, limb cutting) would need to replace it. Mortgages and student loans period could pass 50 years, but since the leaders still could easily die, there would be no qualitative difference from the world we live in.
B: Same as A plus education period as "preparation for life" could be prolonged. People would work less if they could go without food or bed. Everything mandatory or necessary would be way more expensive, because people could work for that for extended period of time. This would make the standards of living worse for 99%. Many strikes would happen, but the 1% would be too powerful to be overthrown. Eventually, the power distribution would remain settled and rigid and people would get used to slavery in time. They would probably sooner or later lose interest in most things that we connect with certain age, including having babies. The Earth capacity for people would grow multiple times. In space time the limits of environment on planets would grow much faster than the number of human beings.
C: The struggle for ultimate power would start as everybody knows that it is the last war and the winner will be eternal. Eventually, there would be only one or very few god-like immortals, the rest of the world or universe would be enslaved by their "laws of physics" which would create the ultimate barrier for their growth and make them to create resources for the deity. If some infinite energy resource were discovered, the free market would lost its point, the gods would lose their interest in humanity and start to live without them, ensuring that they can not follow their way in the future to threaten them.
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**The Old Monsters Never Die**
I am going to assume by immortal you mean "Cannot Die." This is a very, very terrifying prospect. Imagine Hitler, and Genghis Khan have a few beers and end up deciding they're bored with year 45888 of their existence so they decide to start the 27th Reich back up for shits and giggles. If we have a horrible monster walking around today we know that at the very least if nothing else works we can just wait a few decades for nature to take its course and rid us of them. Not so in a world with true immortality, Caligula would still be burning Christians alive at his garden parties, and worse yet, they can't die either. So if you fall into the clutches of such a person guess what? You have centuries of misery and suffering to look forward to performing as a mad man's screaming garden torch.
Point being, in a society with true immortality on an infinite timeline everyone would eventually have the opportunity to be in charge of the whole shebang. This prospect is terrifying to me, because not everyone SHOULD have the opportunity to be in charge. Imagine if a guy like Kim Jong Un could keep coming back to terrorize humanity every few centuries or so for all eternity. Perhaps a method of punishment would need to be devised that if it can't kill them, can at-least remove them from the equation for a long, long time. Perhaps if somebody proves them-self a horrible enough person we could entomb inside of a reinforced concrete block and then dump them off into the deepest part of the ocean to keep them from public influence for at-least a few thousand years. Of course, when they come out they might be stark raving mad and even worse to deal with than when they went in.
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I have a sci-fi/fantasy world with two suns. Only one sun can be present in the sky at a time. A full day-night cycle would be:
1. Night time
2. Sun 1 rises
3. Sun 1 sets
4. Sun 2 rises
5. Sun 2 sets
6. Night time
Is there an astronomical way to explain this?
Edit:
Since people are saying it might not be possible to have a night I should mention that is my least important requirement. My goal is to have one of the suns be inhospitable to life, so people are going to be hiding indoors while it is out anyway. I could use that as a time of rest.
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The most likely orbit is for the planet to circle the two star system. However in that orbit both Suns would be visible at the same time for part of each day. Another option is the planet in a langrange point of the two Suns. Essentially the suns orbiting around the planet, this would result in one sun at a time, but no nights. A third option would be the planet orbiting one sun inside the orbit of the second sun. This results in a day/night cycle, but of varying lengths with multiple suns present for much of the year, and dependent on where the orbiting sun was located.
Possibly the best option, but least likely, is a very delicate balance and results in a slow series of night, day 1, night, day 2 sequence, but only for part of the planet. For this imagine a center of orbit at 0,0. With suns at +1 and -1 on the x-axis. A planet that moved on the y-axis with the ideal rotation speed would see a night-day, night-day sequence with days being alternative suns for portions of the planet. While other portions would see a double sun, sun, double sun, sun pattern.
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An option might be that the planet closely orbits let's say Sun1, while the other star, Sun2, is on a far away orbit, looking more like a very bright star than a sun.
For a good part of the year the Sun2 would appear during the Sun1 night, when of course the Sun1 would be set.
For those times when the two Suns are on the same half of the sky seen from the planet, there would a proper night, while as they move across the sky there would be a longer Sun2 day.
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Yet another option would be to put your planet at the L1 [Langrangian Point](https://en.wikipedia.org/wiki/Lagrangian_point) between Sun 1 and Sun 2, that is on the line between the two suns where the gravity of both suns cancel each other out. While this has the benefit of only one sun to be visible at a time, the drawback is that there is no night time at all, because when one sun has just set, the other has just risen.
Another **major** drawback with this solution is that the L1 point is a point of unstable equilibrium and any perturbation, however small, will cause the hapless planet to leave the L1 point and fall towards one of the two suns, eventually ending up in an elliptical orbit around it. This can be circumvented slightly by moving the planet in a [Lissajous orbit](https://en.wikipedia.org/wiki/Lissajous_orbit) about the L1 point but here too small perturbations eventually grow so large that the system breaks down.
It is possible to posit fourth and fifth celestial bodies in stable orbits around either sun that nudge your planet just so that the perturbations cancel each other out but the math for this is quite intractable (if you know how to solve this type of problem in a general way you have a big chance of winning the Nobel Prize).
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The rise and fall of a Sun is relative to the rotation of the planet and it's axis. On Earth, there are spots where the Sun rises and falls with a Sun in the sky 24 hours per day.
The daily cycle of a planet is 1 rotation, and what you see in the sky is relative to where you're standing on the planet. The orbit of the planet doesn't effect the daily cycle of the sky, but what you see in the sky changes over the course of an orbit.
So you have flexibility with the narrative of what you see in the sky.
You can say that the planet orbits a pair of stars when viewed from the equator are seen one at a time during a daily rotation, but at the polar tips of the planet you see either both stars or none at all. A traveler moving from the equator to a polar end would transition from seeing one at a time to a pair of stars or none.
The closer together the pair of stars orbit each other the further the axis of the planet has to lean to see only one star at a time. All of this is relative to the orbit distance from the suns, the radius of the planet and it's axis.
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**Put your planet in Lagrange 4**
The Lagrange points (as mentioned in another answers) are points in an orbit where bodies can be "parked" due to an equilibrium in the gravital forces of the other two bodies: Here is more detail about the theory:
<https://www.space.com/30302-lagrange-points.html>
So, your center will be "Star 1", and around it, there will be orbiting "Star 2" and "Your planet". The planet needs to be located in the point called "Lagrange 4". With that configuration, when your planet rotates in the day-night cycle, both suns will take turns as you mentioned, and you will also have night (your night will last (more or less) only 1/3 of the rotation time, but you will have night).
[](https://i.stack.imgur.com/qLwdZ.jpg)
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In a multiple star system, including a double star system, the stars have to orbit one another. Which means that their relative positions are constantly changing. The planet will also have to orbit one of the stars, or two of the stars. As the planet's position changes relative to one star, that will change the relative positions of the two stars in the sky of the planet.
In a multiple star system, it is relatively easy to create a set up where the two stars are in a specific relative position in the sky for months or years at a time. It is less easy for the two stars to have the same relative position in the sky for decades at a time, less easy for them to have the same relative position for centuries at a time, and less easy for them to have the same relative position for millennia at a time.
In Isaac Asimov's short story "Nightfall" which was later expanded into a novel, the planet Kalgash has eterrnal day for thousands of years at a time.
See here: <https://planetplanet.net/2018/02/02/real-life-sci-fi-world-11-kalgash-a-planet-in-permanent-daytime-from-asimovs-nightfall/>[1](https://planetplanet.net/2018/02/02/real-life-sci-fi-world-11-kalgash-a-planet-in-permanent-daytime-from-asimovs-nightfall/)
and here: <https://planetplanet.net/2018/03/21/asimov-kalgash-take2/> [2](https://planetplanet.net/2018/03/21/asimov-kalgash-take2/)
For attempts to make a realistic solar system where a planet could have eternal daylight.
AS you can see, the fact that the stars in a multiple star system orbit and move relative to each other make it very hard to create an eternal arrangement of the stars in the system.
The known orbital periods of stars in binary system range from minutes in very close binaries to hours, days, months, years, decades, centuries, millennia, and possibly for hundreds of thousands of years.
<https://en.wikipedia.org/wiki/Orbital_period#Binary_stars> [3](https://en.wikipedia.org/wiki/Orbital_period#Binary_stars)
There are no known examples of binaries with orbits long enough that the two stars would have had essentially the same relative position for billions of years necessary for intelligent life to develop on a planet.
Unless it is possible for a habitable planet to orbit in a Trojan orbit relative to two stars. But in that case the two stars would be only 60 degrees apart in the sky of the planet, and thus would often be seen in the sky at the same time.
So maybe you could have your planet orbit around a single star, and chance factors as the stars in their galaxy orbit around the center of their galaxy causes another star to pass very close to your planet's star for tens or hundreds of thousands of years.
And the star passing nearby might be a lot hotter than your planet's star, and so emit a lot of very bright blinding light as well as invisible ultra violent ultraviolet light that lifeforms on the planet are not adapted to face. So the animals and people on your planet have to change their lifestyles and hide underground, or inside, or under shade trees, or cover up with clothing, when that nearby bright star is overhead, whether that is in the day or the night of the planet's own star.
This article has a list of the calculated closest past and future stars to Earth over several million years, though a passage a lot closer would be necessary for your story.
<https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs> [4](https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs)
It is quite possible that in your story the passing star is not yet at its closest and the future closest approach will be deadly.
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[Question]
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Human society is effectively gone and a new, intelligent species of Chimpanzees has taken over the role as the dominant species on Earth. It has been 40,000 years since the humans fell, so we can assume that all human technology has long been destroyed. Chimp archaeologists are now digging into the fossil records and finding anomalies that can’t be explained. These anomalies suggest that some past intelligent species existed on planet Earth, and that this species was very prolific. My question is: what strange, unexplainable inconsistencies would humans leave behind in the fossil records?
By *inconsistent* I mean stuff that would never occur naturally and must have been caused by the meddling of intelligent beings on nature.
[Answer]
It's pretty well agreed that Human's have left an indelible mark on the planet, enough that even a cursory inspection will reveal out presence for millennia to come. Quick list:
* Mining Operations; the vast majority of the easily accessible minerals and resources have been extracted. Open pit mines have been dug, mountains have been leveled, oil reserves have been used
* Cities; even some 40k years into the future, a buried city is going to be easily recognizable. Large concentrations of metals and pollutants, geometric landscaping
* Landfills, especially with non-biodegradable plastics, will still be around.
* Nuclear radiation; there are some test sites and zones that are going to be hot even so far into the future - [nuclear waste storage dumps will also be easily recognizable](https://en.wikipedia.org/wiki/Long-time_nuclear_waste_warning_messages)
* Climate Change; all that fossil fuel burning will leave easily recognizable trace elements all over the place - polar ice caps, ash layers etc etc
* The Moon!; Bit further out - but the various pieces of tech should be undisturbed on the moon unless they get hit by an asteroid - no weather to wear them away
* Mass extinction; even just going by the records of other animals, humans have been responsible for a mass die off of other species that should be easily recognizable to a future archaeologist.
* Satellites; I'm not entirely sure about this one, but there still should be some (non-functional) debris and bits and bobs floating around in orbit
Essentially there's any number of things that a future race on Earth could use to discern our presence, even 40k years into the future, and that's without any special effort on our part. Once you factor in time capsules and "fling a light into the future" projects, it's pretty much certain
[Answer]
If we focus just on biologically originated [fossils](https://en.wikipedia.org/wiki/Fossil) (as opposed to non-biological materials and artifacts), even there human civilization leaves a very prominent mark in history.
1. Proliferation of new sub-species. Fossil records would indicate that in a matter of centuries, certain species have become totally dominant, and there is no natural explanation for it. Chickens, cows, pigs, sheep and goats have outstripped most other lifeforms, while undergoing quite abrupt evolutionary change along the way. Human fossil records also will be very prominent;
2. Extinction of many older species. While extinctions happen naturally, this one would be going alongside the proliferation of domesticated animals and would not be seen as natural;
3. Unusual geographic extension of fossil records. Animal bones and tropical fruit seeds will be found in all climate zones and all latitudes.
[Answer]
If you're talking about 40,000 years in the future, probably another big one is that the carbon cycle will still be out of whack. It'll take longer than 40,000 years for all of the CO2 we've pumped into the atmosphere-ocean system to be re-absorbed into sediments.
Plastics are likely to persist since there are no organisms capable of digesting them. The only way to remove them at the moment is photooxidation (which causes incomplete degradation) and burning. Some metals will oxidize and be remobilized, but a lot of them will still hang around in the shape of what we created, if not in a reduced oxidation state.
Have you seen Gavin Schmidt's piece on this same idea, only with a longer timescale (55 million years)?
<https://motherboard.vice.com/en_us/article/3kj4y8/gavin-schmidt-fiction-under-the-sun>
[Answer]
All of these assumptions assume that Humans just up and died. a gradual decline or massive war, or impact event could easily change some of these results.
**Biological**
While the large number of extinctions have already been covered in the other answers. its worth noting that humans bones would survive in certain places but definitely not all. the majority of climates in the world will be unlikely to provide reliable sources of human remains. however some places will, areas with very low humidity is a very good start. and those remains may have some form of prosthetic or obviously refined additions. Certain types of fillings will still be evident. along with metal plates holding bones together etc.
The problem is will they really survive... for most of the world no. the reason: it is becoming quite common to cremate our dead. far more common than it has been for a 100 years or so. so there will be evidence, but alas it will be hard to find
**Non-Biological**
Even "Non-Biodegradable" plastics, degrade over time, and 40,000 years is long enough for this to happen, they won't be gone completely but they would only appear as particulates in a sedimentary layer in Core samples, so anything made of plastic will most likely be gone. metal structures around the world would have collapsed and while it would be evident that some of this structures existed at some point the materials would be largely unclear at first sight (yes in depth analysis would show they were RSJs etc). but this wouldn't be as important as Steel. Steel does not occur naturally, it an Alloy, and the Modern Human World is basically made out of Steel. from buildings to car parts etc. this would be the first clue as to at least an industrial level society had lived here.
The Pyramids would still exists, yes it would continue to crumble, and most likely appear to be massive sand dunes, but once excavation happened on these big mounds they'd find the stone work to be definitively refined and cut, even to this day thousands of years after being built after the limestone has eroded from the faces and the stone beneath has begun to crumble. the stones that line the internal chambers are still in almost perfect condition.
Gold, nowhere in the world does gold occur naturally in such large and pure amounts than in National Reserve Stores. the Bank of England, US Federal Reserve etc all have large amounts of Gold stored away. if the future society found these, they'd be 100% certain that this was some form of financial store. even if everything surrounding the Gold had collapsed and turned to mud (not literally) the Gold would still be perfect evidence.
Any material in significantly higher purity than occurs naturally would point to a refining process. then each of those materials would then show what level that society was at: little Steel, little Gold, but high concentrations of Brass and Iron, pre-medieval times, Steel, Gold (not super high purity though) Brass Copper etc. points to medieval. Steel and gold, and copper etc, industrial. and then Palladium super pure Aluminium, pure gold etc. Modern age.
**Radioactive**
if we assume the future society uses anything similar to Carbon Dating, then they will quickly discover that there was a huge amount of radioactive material in the atmosphere at one point. Carbon/lead dating easily show these effects from the atomic testing in the 40s and 50s to the Chernobyl Disaster and presumably Fukushima as well. and again certain materials point toward nuclear tests. Cesium isotopes for example are evident in lake beds world wide after nuclear tests and these show up in Lead Dating techniques
**Space**
While earths Satelites will have all re-entered in 40,000 years, the third stage of Apollo 12, is in incredible high orbit of earth, it didn't reach its intended trajectory and got flung out into solar orbit and then re-entered Earths Sphere of influence, at this time it is unclear if this will enter Earths Atmosphere but its possible it'll be out there for good.
The Lunar landing sites are have test equipment and parts that will degrade over time due to solar radiation, but most of it will take so long that they will survive 40,000 years
Voyager 2 is on its way out of the solar system, it was nothing really to worry about, it will probably be pretty banged up in 40,000 years, but it will still be flying out into space for someone to find.
[Answer]
After 40,000 years there won't be much left of most of our cities and our mines and landfills will only be tiny geographic samples that are easy to miss in a widespread survey. There are a few things that will survive that long though.
* Processed Gold and Platinum jewelry, they'll be widespread, found in the forests that grow over our graveyards and in the gravelly alkaline soils where our concrete cities have crumbled and they won't corrode they'll be there a long time.
* Other Gold artifacts like bullion bars or coins will similarly last a long time and show clear evidence of written symbols etc...
* Cut Gems in general will be a sign of artificial tampering to someone who knows what they're looking at.
* Mount Rushmore and similar monuments and smaller statuary in highly stable rocks like Granite or better yet Quartzite. These will last millions or even billions of years in a recognisable form depending on how geologically stable the area is.
* Radiation, there will be pockets of intense radiation from nuclear power plants, and nuclear waste storage facilities. There will also probably be small low level but detectable traces from every hospital and clinic that once did radiotherapy.
* Monumental structures, the Egyptian Pyramids, the Great Wall of China, Uxmal and it's peers in the Americas, Stone Hedge, anything that's really big and made of stone will be eroded but still there.
* Isotopic traces, there are a number of longlife isotopes like Uranium-236 that don't normally exist in nature and have half-lives measured in millions of years that we've produced very large quantities of that will still be around.
* Chemical traces, as many of our artificial polymers decay they produce organic (as in based on carbon chains) compounds that don't occur in nature and so will persist in water, soil, and wildlife because they don't take part in the carbon cycle until broken down further by UV Radiation.
* Cutlery and DeLoreans, and anything else made largely of Stainless Steel, Stainless Steel will remain in whatever form it was cast in almost forever unless exposed to a highly acidic environment or extreme heat.
* Elemental Aluminium, in nature Aluminium is only ever found as $Al\_2O\_3$ at various levels of purity, so to find even small amounts of it in it's pure reduced form would be quite telling. Because of the structure of the Aluminium Oxide that forms on the pure metal it prevents further corrosion in most environments so things like Aluminium engine blocks are still going to be large unaltered after only 40,000 years in salt-free conditions.
[Answer]
LDPE plastic can last 40,000 years in cold underground conditions. it's mostly susceptible to UV's and light, so that's toys, bottle tops, tools, glasses, plastic bags.
Mountain road works, mines and tunnels cut into rock can last 1-5 million years. We can find Neanderthals and their flint tools in great numbers from short time spans around 40k years ago, on riverbanks and uncovered by wind in the Sahara.
[](https://i.stack.imgur.com/94fst.jpg)
Based on thousands of road and rail works that will stay visible for 1-10 million years, they can dig to investigate them. They will find road, litter, barriers, and the road will lead to cities. So when you uncover a human road in the next 5 million years, a bit of radar detective work may reveal all the towns in the country.
a 12000 year old temple, Göbekli Tepe was only 2-10 meters underground, so a city like Dubai and Dallas would still be partially uncovered by erosion for 100,000 years, exposing bands of tarmac (which stays recognizable for millions of years), millions of bottles, metal, cars made of zinc and aluminium, chunks of rust the size of boats and cars. I'd give some major cities 20 to 50 million years, to cover the last cement bridge pillars and durable monuments.
Humanity's fossil imprint is easily 1000 times more massive than a neanderthal's, in kilotons of artificial constructs, and many times more durable, so you'd have to extend the time frame to about 500,000 years or 20 million years to make human's imprint difficult to find. A chimp would take about 2-10 million years to evolve to a human sophistication level.
Common and clear signs of humanity will be easy to find for the next 1-5 million years. If humanity survives until 2500, the durability and quantity of the fossils may be about 10 times higher, so perhaps 10-20 mn years.
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I'm researching possible materials that maybe be used in the far future. I came across something called metallic oxygen. If oxygen is compressed to 10GPa, it turns into a dark red solid O8. If this is compressed further to 96GPa, it undergoes another phase transition and becomes metallic.
Right now it can only exist under the ridiculous pressure, but given today's knowledge of chemistry and material science, is there some possible way to make this material stable at atmospheric pressure, while still being mostly metallic oxygen, not just some oxide? Perhaps a mix with other high pressure allotropes that chemically hold each other together or cancel out each other's energy, forming a sort of a stability well?
My knowledge of materials science is not that great, so I don't even know if my question makes physical sense, but hopefully someone can get this and help me out.
Edit: making my question more precise. I don't expect the metallic oxygen to be stable in pure form. What I think I'm looking for is some kind of alloy based on metallic oxygen that would be stable at lower pressures. It's not important what it's mixed with as long as it keeps the density and structure of metallic oxygen. I want to know if this idea makes sense scientifically, if it's at least theoretically possible to have such an alloy.
[Answer]
The metallic state of oxygen would last only as long as there'd be a monstrous pressure keeping it that way. Even the most compat and solid water ice will not stay that way if artificially created in an incompatible environment -aka: You can make ice cubes in Dubai, but you can't keep them in the sun for long.
And the conditions for metallic oxygen are so exotic as not to find anyplace on or under Earth to maintain stability
[Answer]
The stable existence of any substance is driven by its Gibbs free energy, as compared with that of other possible substances: the one with the lowest Gibbs free energy exists, the others are less stable and turn into the more stable. I.e. liquid water Gibbs free energy is lower than that of ice above 0 C at 1 atm, therefore ice melts above that temperature.
As you state, metallic Oxygen forms only at ridiculously high pressures. We can translate that as "only at those pressures the Gibbs free energy of metallic Oxygen is lower than normal Oxygen".
This is something with which we cannot really fiddle: it's a consequence of physics and chemistry laws, and unless we are so lucky to have some substance which is metastable (like diamond, which is not the lowest Gibbs free energy configuration at standard condition, but it is stable unless you warm it up, turning it into graphite), we have no way of having metallic Oxygen at our standard conditions.
[Answer]
**Unlikely, because Oxygen is Too Reactive**
It sounds to me like you're hoping that metalic oxygen will have a metastable form, acting metallic even after it is returned to room temperature. A real-world parallel would be diamond, which is a metastable form of carbon.
Unfortunately, diamond is able to retain its form because it has a stable crystalline matrix that ties up its available electrons. You need to provide a lot of energy to break up those carbon-carbon bonds, thereby allowing the diamond to break down into a lower-energy form, graphite.
A side effect of these carbon bonds is that diamond acts as an electrical insulator. Put simply, it doesn't have enough free electrons to conduct electricity.
Metals, however, are characterized by electrical conductivity, and I don't know if you could call something "metallic" if it was an insulator. Certainly when we talk about "metallic hydrogen" we do so because it becomes electrically conductive (with an associated increase in optical reflectivity).
Gaseous oxygen is a diatomic compound. If you could compress a large amount of oxygen into a metallic state, it would necessarily break down into single-atoms, thereby freeing up valence electrons so it can act like a metal. But all those free electrons will allow the oxygen to react with whatever it encounters, and chemical reactions with oxygen release a lot of energy.
I speculate that the first reactive compound which came into contact with your metastable metallic oxygen would combust explosively, triggering the nearby oxygen to revert to diatomic (gas) form as well. Even a single spec of dust could do that, or perhaps a cosmic ray.
If you have any doubts about the explosive reactions triggered by pure oxygen, read about the Apollo 1 launch pad fire, or the (ig)nobel prize awarded to George H. Goble for lighing a barbecue grill with liquid oxygen. Given the relative density of metals vs. gases, building anything from metallic oxygen would be asking for trouble, because you're just concentrating the reactants.
Since you asked about metal alloys, I don't see how they could possibly reduce the danger associated with room-temperature metallic oxygen while allowing it to remain metallic. Anything you alloy with the oxygen will want to form a compound with that oxygen, and give off a lot of energy when it does.
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# The Idea
I currently play with the idea of a story where the protagonist travels a foreign world, visits places, studies customs hand history of locals, meets with survivors of historical events and takes a look at the physical characteristics and biology of the inhabitants and also their technology. It's basically like a fictional documentary and the protagonist is doing the research and narrating it.
# The Species
The dominant life form of that world can be described as being basically dragons (the protagonist is of an other non human species). They look like you would expect a standard dragon to look like (four legs + a pair of wings). An adult dragon usually has a shoulder height between 1.5m and 2m (depending on subspecies and age and region). They walk an all fours but do everything else on two legs, basically sitting to have their hands free.
Of course they can spit fire and fly.
## Biology
As mentioned the Dragons are physically mostly what you would expect. They do look like reptiles (although some have birdlike feathers) but they are warm blooded and have reproductive organs that resemble much more those of a mammal. The Dragons are basically ovovivipary. Their young one is born alive except when environmental conditions aren't good e.g. there is not enough food or the female gets weak or sick. They can't actively control it but it could be induced by medication i.e by taking hormones. In this case the female lays eggs which shortens the pregnancy a lot. Most Dragons do not feed milk to the newborns.
The dragons are extremely long-living (500+ years are normal and they usually die by accident or sickness), robust, and not very fertile. Some female may engage in sexual activities regularly over 500 Years and never get pregnant but the opposite case also exists. Some females are very fertile and often act as surrogate mothers for other dragons that have no luck with getting a child by themselves. Artificial insemination almost never works.
The fertility issue is subject to research but the cause or a cure is still not found. According to their research almost every female should have no problem getting pregnant. The fertility issue over was incorporated in the dragnon's main religion.
The average birth rate is slightly higher then the death rate. Population grows steadily but slowly and is, at the time when the protagonist visits their home world, at about seven milliards, split across several worlds an colonies.
If the pregnancy is successful the female gives birth to only one child (or lays one egg) at a time. Twins are extremely rare and usually reason for a big celebration. Complications during pregnancy or birth are very rare nowadays.
The young ones mature very quickly and grow fast in their first few years and then slowly grow to their full size over many years.
## Culture
Most dragons have in common that they're curios and playful. They love games and riddles, in fact, in their home world they are so obsessed with games that they even settle major conflicts with games and sports.
The dragons, despite being technologically very advanced (colonizing space and have interdimensional travel), not only still look very feral, they value their feral roots and instincts as well, instinct driven behavior still plays an important role in their society and social interactions.
The young ones enter the school system at age four and visit school for about six years. Between the age 10 and 12 they usually get sexually mature. At the age of 10, they are allowed to move out, it's also the age where they're granted their first adult privileges, although not technically adult by the law (they are now young adults). They can now choose to enter a secondary school and study, get a job (usually apprenticeship) or travel the world before entering a career (which is tradition often followed). They can also get involved into some levels of Politics (like regional voting or joining a party).
The dragons live (at the time the protagonist visits them) in a post-scarcity society (similar to Earth in Star Trek although not that perfect). Medical science is very advanced and early pregnancy wouldn't bear much risk, STDs are rare and curable.
They have a tight social net of benefits that would support a young mother/father (males and females are treated equal in any way) in need and many dragons, that are unlucky with getting offspring by themselves, would like to adopt a child. Generally, rising a young dragon is often not done by a single pair of parents. Instead it's more a group effort mostly because most relationships are polygamous. Relationships are usually short.
Life long bonds are rare and marriage is a foreign concept although it happens, is influenced by other races and cultures, and usually only done in interspecies relationships with races that have shorter lifespans.
Interspecies sex happens too, but there are no reports of a female dragon getting impregnated by a partner of a non-dragon race while males seem to be able to reproduce with some non-dragon races. In that case the offspring is always of the mothers race, so dragon-male + non-dragon-female = non-dragon offsping.
Dragons utilize inter-dimensional travel and colonize other "planes" instead of relying very much on space travel. They have contacts to many other species (also visited our earth at some point) some are just as advanced.
Sexual interaction is mostly not for procreation but more for the fun. Contraception is effective but usually not seen as needed since the dragons are very unfertile anyway. Therefore "teen" pregnancies are very rare too.
# Why could sex still be not allowed for the young adults?
From my design of the race and its society I don't see why it shouldn't be perfectly okay for the young dragons to engage in sexual activities. It fits a race that gives in to it's instincts, like the mating instinct, where pregnancy and disease is a minimal risk and where sex could be seem to them as a form of play.
I want the dragon race to be a bit more relatable to human standards and want them to have good reasons why they forbid or at least strongly disprove that young dragons engage in sexual activities with each other and with older dragons as well.
I first thought of the dragon's courtship ritual maybe being dangerous and violent (like Klingon mating habits), therefore making it risky although everything else is not a problem. But I rather like my dragons to be nonviolent in any way that is not fighting in war or something like martial arts in sports.
[Answer]
Your dragons are into Eugenics - the idea that you should think carefully about who to mate with in order to create genetically ideal offsprings.
This might actually make sense. Low fertility and long lifespan means that dragons will have a rather long generation cycle. That means the species as a whole will evolve much slower than other species. The dragons are afraid that if they don't make wise breeding decisions, they will be evolutionarily overtaken by more fertile species.
Young dragons are not trusted to possess the maturity to decide who to mate with.
Further, they have not yet proven their abilities in life. Nobody knows yet what their genetic abilities are. So it is not yet possible to judge who they should mate with (or if they should mate at all).
[Answer]
This isn't the answer you're looking for, but your premises strongly imply that you won't get any such taboo or law.
**First**: you state that technology is far enough that complications in pregnancy have been effectively eliminated (trivial risk) and that even being pregnant young isn't going to pose a real health risk. You've thus eliminated one of the two key hazards of early pregnancy.
As for having sex in general, you've stated that STDs have been effectively eradicated, eliminating the health risk there. You've also stated that sex has become more for recreation than reproduction: this is generally the natural result of the above factors, but it also rules out any idea that mating in itself is dangerous for either partner (or it would not be done for fun). Therefore, your dragons have no reason to forbid sex (and potential pregnancy) on medical grounds.
**Second**: you state that there is a strong social safety net for any young mothers that might need help. They won't be left to raise their child alone, but will have support of the sort that poor families on Earth could only wish for: that's the other major hazard of early pregnancy dealt with. Therefore, sex won't be forbidden to the young for financial reasons.
**Third**: you state that the fertility rate is extremely low, even considering their long lifespan. Teen pregnancy is thus a very unlikely risk, even if it was something to be seen as problematic in itself; see the first two reasons for why you've already set up a world where it isn't a problem. You definitely won't see any taboo against the young having sex on grounds that there would be too many children.
**Fourth**: you state that their society has strong respect for natural instincts, that even in their modern civilized society those instincts still play a notable role. The mating instinct would logically be respected as much as the rest (if not more, for being the instinct that continues the species), and you've mentioned that they tend to curiosity as well; their bodies would naturally be one such object of curiosity. Therefore, given all of that, forbidding young dragons from acting on that instinct would run *significantly* against what you've established their society to be, particularly given how the other premises show that there's no material risk to them having sex.
**Conclusion**: your dragon society is not going to lift a finger to stop young curious dragons from indulging themselves by having sex. If anything, the older dragons are more likely to *encourage* the young to have sex, to answer their curiosity and to avert population decline. Each female in a given species must have (on average) two children who themselves survive to reproduce to maintain the overall population: in practice, more than two children must be born to compensate for those lost without reproducing (before industrialism and sanitation, fewer than half of humans survived their first ten years). With such low fertility as you're stating, your dragons need to be regularly trying to have children just to keep their population steady.
I'll also point out that **"human standards" are *far* from universal**, especially concerning the young and their sexual activities. Granted, in modern times most Western societies have the idea of "age of consent" (this being generally some time after sexual maturity is attained in the typical individual) before they can have sex. This is very much a modern construct: wind the clock back a few hundred years, when arranged marriages were more common, and you often find women married by fifteen with multiple children before twenty *despite* the health risks (which in your dragon society are avoided). Or look outside the admittedly widespread Western (mainly Christian) ideas of morality, for there are many countries where such practices are *still* common and seen as being normal; note that I am passing no judgement on those viewpoints, merely pointing out that they exist. There are almost two hundred recognized nations on Earth today: normal to one is baffling to another and horrifying to a third.
If you still insist that your society must have a taboo against the young having sex, it's not going to mesh with the rest of your world as presented in your question. You'd have to change at least two of these major premises to make it plausible, at which point you've made significant alterations to your dragon society such that it might no longer be recognizable.
[Answer]
You might consider the difference between "recreational sex" and partnership/marriage for procreation.
* In many societies, humans were expected *not to marry* until one partner (usually the man) could earn enough to support a small family (usually a non-employed woman doing all the domestic work plus a few children). That's changing these days, with the expectation that both partners may be working or that children may come out of wedlock.
* Many societies accepted that humans would *become sexually active* at a younger age. This is not *approval*, elders would advise against it, but society accepts that there is no fighting young fools. There are safeguards like the age differential you mentioned -- two young fools together are OK, one young fool and a scheming adult are not OK.
A key question would be if the dragons have effective contraception. If no, expect sex to be disapproved until the partners have a prospect of raising a family. If yes, the dragons can *afford* to be more tolerant.
[Answer]
Mating (if even seen as important, it might not, depending on the rearing customs and biology) would be OK somewhere at the end of the blunder years, around the time where other dangerous or life-changing decisions (for self and others) are acceptable. Think about voting, mind-altering (alcohol), killing (soldiers), entering contracts, running for office. Also think of the age at which behavior is starting to get sanctioned by society (laws) instead of family.
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Following this [question](https://worldbuilding.stackexchange.com/questions/112853/railgun-launched-nuclear-warhead "is this even remotely a good idea"), in the exact same setting
>
> I'm making a world where sub-FTL interstellar travel is a thing, and
> so is interstellar war, but for the purpose of this question we'll
> assume the scale to be of a single system.
>
>
> Spaceships have evolved quite a bit since our current era, and they
> range in size from several meters (something like 2 times larger than
> your average air superiority fighter, having a space-worthy manned
> vessel can't get any smaller than this in my universe) to up to 20
> kilometers in the shape of a scaled-up space submarine.
>
>
> Weapons comes in varying shape and size (proportional to the ship that
> bear them) and can be split in 3 categories:
>
>
> * Missiles : Just your everyday payload carrying self propelled
> firestick, you could also call them torpedoes at this point, it
> doesn't really makes a difference as far a I know. They won't get
> bigger in size than an ICBM and the tech didn't evolve much aside from
> targeting and space-worthiness.
> * Lasers: They are mainly used as a countermeasure and/or to mess with
> enemy targeting systems at close range (and occasionally to blind the
> enemy commander trough the window as a prank).
> * Railguns: This is where R&D was the most successful, since those guns
> can get pretty big (remember the 20km ships?) and the biggest
> projectile to date is a whopping 100m long and can travel at 30Km/s.
> Picture throwing Saturn V at the enemy vessel). Please note that for
> smaller projectiles the speed can get up to 150km/s, but that is a
> very specialized gun and the average is less that 100km/s for a decent
> gun.
>
>
> Concerning energy requirements, capacitors went a long way and are now
> extremely efficient, as well as cooling, even in space (firing a
> railgun more than once won't melt it for the first couple consecutive
> shots) and fusion is the go-to mean of energy production across the
> civilization. Dyson sphere project started in some systems, and the
> question of the access to the host star sparked the wars in the
> systems.
>
>
>
This time I want to ask you guys about the feasibility of a 3 stage relativistic projectile that would work as follow:
1. The first stage is a railgun that get the payload up to 150km/s over a 18km distance (hoping the acceleration doesn't destroy too much my payload)
2. Second stage comes when the projectile is at safe distance for [ablative laser propulsion](https://en.wikipedia.org/wiki/Laser_propulsion#Ablative_laser_propulsion), the ship firing directly at the rear of the shell, further accelerating it to [calculations needed] km/s
3. Third and last stage is a mix of a [HEAT charge](https://en.wikipedia.org/wiki/High-explosive_anti-tank_warhead) and a [casaba howitzer](http://www.projectrho.com/public_html/rocket/spacegunconvent.php), and this is the last and only chance for the firing ship to make any trajectory correction by turning the shell around using tiny thrusters and detonating the nuclear charge, at a safe distance of course (maybe 1 A.U. or less, I don't exactly know what a safe distance is when 10,000km is considered point blank range in space).
Such a weapon isn't stealth-friendly in an already non stealth-friendry environment, so i'm looking to go really fast, *really fast*. Energy expenditure is out for simplicity's sake, and we shall consider the shell after the third stage to be going at relativistic speed (more than 1% of C), be hardly detectable and a pain to deflect (you don't want to create a relativistic could heading your way by destroying it... or do you?)
And now for the (somewhat) concise question: **Would such a weapon system be realistically possible?**
Please note the tech level to be several centuries ahead of today, so extrapolating current tech to the limit of physics is acceptable.
Feel free to comment below for any missing info on the context if needs be (also feel free to edit for spelling, my previous question highlighted the fact that I utterly suck at it).
[Answer]
**First I want to say something about RailGuns in General**
One of the sites you linked to talks about Children of a Dead Earth, which takes a common view of hard-science space combat, so I will talk about that.
For ships you have two ranges. At one range orbital mechanics are important. Ships are far away. However, you can easily figure out a ships acceleration, mass, ect because of all the heat it is dumping into space. You know where it is, and where it will be if it continues on its current track. You also know the limits of where it might be if it changes course. However, at this range, it takes awhile for your projectile to get there. Even at your "point blank range" of 10,000 km, it will take a 100 km/s projectile 100 seconds to reach its target. If the the target started a hard 5g burn right away, they would be 250km away from where you expected to find them. Small distance for space, but easily big enough to miss.
What about saturating the area with fire? Looking at the size of a submarine, best case for the shooter, your 20km ship has a cross sectional area of 20\*1.4 = 168 km^2. The target zone has an area of 196,000 km^2. This gives a individual projectile a 0.08% chance of hitting. If you simultaneously launched about 70 of them, you would have about 50/50 odds of at least one hitting. (99.02)^70. Assuming the enemy rotates to present a smaller target zone to you, this can be significant worse (though doing so would probably mean any hit would be catastrophic, straight down the length of your ship).
The math gets much worse at longer ranges, though you can achieve saturation by firing a bunch of projectiles at once, but the ones you fire first go slower, so they all arrive at the same time. But ultimately, the target zone grows quadratically, with the additional distance the ship can put on, and that grows quadratically with projectile travel time.
**NOTE:** This is assuming you are already correcting for the fact your opponent is moving. This math is based on the fact that your opponent could start speeding up, or start slowing down (or just stop speeding up if they were already accelerating). The only concerns that the defender has is fuel, what impact they will have on their orbit. I suppose it could become an issue of attrition. Which ship's crew will not be able to handle the gees first, or which ship needs to burn to correct their orbit first.
My point being is that you really want your projectiles to be guided if used at any real range.
The other engagement range is suicide range where it becomes like a knife fight. Ships don't have time to dodge, and the battle (or at least each engagement) is over in seconds. Ships could easily have relative delta Vs 10km/s or more.
The [one page you linked to](http://www.projectrho.com/public_html/rocket/spacegunintro.php) seems to argue that the "inner engagement envelop" begins at 1 light second out, and rail guns come into serious play there. Honestly I don't see it. You are still look at travel times of close to an hour for rail gun projectiles. You could accelerate at a measly 1/10th gee and deviate nearly 500km from your expected position. You are still looking at a huge light cone.
At your knife fight range. What would knife fight range be? Usually people define it at about 1/10, or close to what you point blank range. Honestly, I have never seen a convincing argument for the use of traditional rail guns in realistic space combat (still does not mean they aren't cool).
**As to your Weapon**
Simplify it a bit. Rail gun launch your missiles. A railgun projectile, depending on how you do it, can be fairly stealthy. Once the missiles get within a "close distance" then they turn on and put on the steam and course correct as needed. I don't know why I don't see this proposed more often.
It also seems like overkill as written. Unless this is a WMD to be used against fixed targets (Which changes things ALOT).
But lets look at is as written.
**First Stage**
150 km/s in 18km. That gives you an acceleration of about 63,000 gees. That's a lot. A = V^2 / (2X)
Lets assume your projectile is made of a material on par with steel.
Let look at the compressive strength of steel, 250 MPa, this is the pressure it can withstand before breaking.
We multiply our accerlation by M, and the pressure by A, and we can get a ratio of mass to cross sectional area for our projectile. 396 km / m^2
The mass will be equal to the volume times the density. Volume will be area times length. So our ration of M/A becomes A*L*p / A or just L\*p
The density of steel is 7.85 g/cm^3 or 7850 kg/m^3.
So Lp = 396 . L\*7850 = 396.
Your projectiles need to be shorter than 5 cm to avoid breaking up. So this is our first problem. *Your launcher needs to be longer.*
**Second Stage**
Laser Ablative Propulsion will take mass away from your projectile. It has a fairly high ISP, and you can get your delta V using the rocket equation V = 50,000\*ln(mi / mf)
(The ISP can vary a lot from around 200 to up to 5000 ideally. I am going with the ideal materials, ect).
So if you use up half your mass, you will gain about 36km/s. IF you use up 9 tenths of your mass, you gain about 115 km/s. For a 150km/s gain, you need to ablate away all but 5% of your mass.
So even if we get up to 300 km/s total with the laser ablation, we are still only at a tenth of a percent of light speed (light is fast).
Also, because of light lag, you can't do a lot to adjust to distant targets in this phase.
What do we need to hit 1% light speed? We need to gain close to 3000 km/s during this phase (technically a bit less, but the rail guns contribution isnt really that much, only about 5%).
That gives us a mass ration of 1.14 x 10^26. OUCH!!!! Honestly Laser Ablation is good because you don't need to carry an energy source with you, but is not ideal for this application.
**Third Phase**
This is basically [Nuclear Pulse propulsion](https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion) which does not have a maximum ISP much better than the ablation (though the minimum is much higher). Once again, you need to loose mass to get faster. By loosing a similar amount of mass you need to loose about 95% of your mass again.
**In Conclusion**
Not really possible. You could replace the final stage with some sort of [photonic rocket](https://en.wikipedia.org/wiki/Photon_rocket) (sort of like NPP). This is actually what [project Daedalus](https://en.wikipedia.org/wiki/Project_Daedalus) proposed using. Using one (if they ever exist) could let you get to 1% light speed with only using half your mass. Much more feasible.
The laser ablation won't really help you much.
The other option is longer rail guns. Make your railgun 20x longer and now you hit 1% light speed. There are other problems of course. As the speed gets high friction is doing work faster, which will cause it to heat up like crazy, but it seems like you are already assuming they've got solutions to problems like that.
[Answer]
It looks highly complicated and unpractical.
First of all, you are stitching together multiple systems which are supposed to work one after the other, and an old motto among reliability engineers states that
>
> What is not present cannot get broken
>
>
>
Let's then give a look at some basic physics equations.
The distance covered starting from still can be calculated via
$ d = 1/2 a t^2$
while the velocity can be calculated as
$v = at$
Based on your constraints of $d = 18 \ km$ and $v = 150 \ km/s$, I get an acceleration of about $600 \ km/s^2$ and a time of about a quarter of a second.
That means 60000 times the acceleration we experience on Earth. If you push 1 kg with that acceleration, the projectile will experience a force equivalent to the weight of 600 tons!
I have an hard time figuring out any precision mechanism that can withstand such forces without breaking apart. And after that smack, you want also to use the other two stages...
My advice would be: go simple. 1 rail gun on hormones is already enough for the suspension of disbelief. Don't challenge it further.
[Answer]
The ever handy [Atomic Rockets](http://www.projectrho.com/public_html/rocket/spacegunconvent.php) site provides the sorts of details and tables to do the calculations you want, but there are actually several simpler ways to think about these things (before pulling out napkins to do calculations)
First off, kinetic energy is a truly awesome thing in a space setting. The magic equation is Ke=1/2Mv^2. Since velocity in space is astonishingly high by the sorts of standards we are used to, the "v" suddenly becomes extremely important. At the very modest speeds of 7km/sec in earth orbit, flecks of paint which peeled off boosters or satellites suddenly become dangerous projectiles capable of damaging the heavily armoured windows of the old Space Shuttle and the [ISS](http://www.dailymail.co.uk/sciencetech/article-3587882/What-happens-tiny-fleck-paint-hits-space-station-Tim-Peake-reveals-crack-ISS-window-debris-collides-craft.html). Interplanetary velocity just goes up from there, the fastest any unpowered object can go and remain in the solar system is *72 km/sec*. Punch that figure in your calculator and look at the number of Joules of energy in the result.....
In Science Fiction, there is a small convention of terming the energy of kinetic projectiles in space as "Ricks" of energy (after [Rick Robinson](http://rocketpunk-observatory.com/home.htm)), who pointed out that an object moving at a leisurely 3km/sec has the same kinetic energy as its mass in TNT. You could strike a spacecraft with the used kitty litter from the ship's cat's litterbox and have the same effect as using an explosive warhead.
As for actual rail/coilguns, here is a relevant section from Atomic Rockets:
>
> As an example, suppose we have a synchronous coilgun, and that the coilgun can generate 1 tesla fields (a good number that will not saturate the ferromagnet). Our presumed ferromagnet is probably mostly iron, with about 8000 kg/m3. To reach 100 km/s, you will need 40 TJ per cubic meter of projectile. Since this is 100 million times the energy density of the field, you will need the projectile to sweep out 100 million times its volume in order to accelerate up to the desired speed. This means you need an accelerating track 100 million times the length of your projectile. If the projectile is the size of a dime, with 1mm thickness, you will need a 100 km long track. If 2.5% of the energy goes into the projectile as heat as a result of inefficiencies, you get 100 GJ of heat per cubic meter of projectile, or 12 MJ/kg. This is three times the specific energy liberated by detonating high explosives, so you can expect your projectile to explode like a bomb inside your coilgun barrel. Consequently, this appears to be an unworkable design.
>
>
>
So some adjustment is in order.....
The last thing to think about is your definitions. You state "Relativistic" projectile, but the generally accepted definition of [RKKV's](https://infogalactic.com/info/Relativistic_kill_vehicle) is a weapon moving at a large fraction of *c*. When you are slinging weapons around at that speed, you are presenting existential threats to not just spacecraft, but space stations, small moons and asteroids, many of which would likely be inhabited in such settings. A miss or deliberate strike at an Earth-like planet is likely to damage continents, or deliver the sort of energy that "dinosaur" killer asteroids do. Boldly announcing or using such weapons (regardless of how improbably long or powerful the launcher has to be) is likely to trigger an arms race, given that anyone capable of actually fielding such a weapon could simply end your entire civilization. Based on many of the factors already listed, it actually seems likely that if such things could exist, they would be more like shore batteries mounted on asteroids and moons to take out enemy spacecraft at long range, rather than spacecraft weapons themselves.
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Can a humanoid that doesn't have ribs but instead has solid bone plates function properly ? Imagine plates starting from upper trapezius to the lower back and the obliques but leaving open the belly for pregnancy, obviously the chest area is covered.
[Answer]
**Turtles do fine with solid bone plates instead of ribs.**
[](https://i.stack.imgur.com/OVzoI.jpg)
<https://reptilis.net/tag/turtles/>
The thing about vertebrates is that we need to change the size of our thorax to raise and lower pressure, thus moving air in and out. You could not have a circumferential rib cage like a pipe because you could not change the diameter. You would have to have some silly deal like the head and abdomen shrinking into the tube then popping back out, changing the volume by changing vertical extent of the thoracic cavity. Your humanoids' heads (and shoulders) would slowly bob up and down at all times with their breathing. Actually there is a lot to be said for that setup.
The turtles, though - the top and bottom shells are not connected with bone at the sides and so they can expand and contract the thoracic cavity and breath in a way similar to how we do. If you do not like the head bobbing humanoid (think about it, now!) you could have a turtle humanoid.
[Answer]
The problems with a fixed/solid ribcage are many. For instance:
1- It will immensely reduce the mobility of your creatures. Our (mostly empty) ribcages don't hinder our motion in most directions simply because they are mostly empty. A solid ribcage creature would have extreme trouble bending beyond a certain degree. Touching the ground without crouching would be simply impossible.
2- It will also increase the weight of your creature. Bones tend to be heavy and a solid cylinder of bone would be really heavy, further decreasing the mobility of your creatures. They would require a lot of energy to run, and then again, they would have little stamina.
3- If your humanoids are any technologically developed race, it will be extremely difficult for them to perform chest surgeries, considering that they would have to either cut open the ribcage (which would trigger a host of its own traumas) or operate very very carefully through an abdominal incision.
4- As Willk has already mentioned, your creatures would have extreme trouble breathing quickly. A solid ribcage would have zero flexibility and hence would be impossible to increase or decrease in diameter as the creature inhales and exhales. You would indeed require a different mechanism for allowing change in volume of the lungs.
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I was just reading the Wikipedia article about the [1961 Goldsboro B-52 crash](https://en.wikipedia.org/wiki/1961_Goldsboro_B-52_crash#Bomb_recovery). In the bomb recovery section there is this quote (emphasis mine):
>
> Excavation of the second bomb was abandoned as a result of uncontrollable ground-water flooding. **Most of the thermonuclear stage, containing uranium and plutonium, was left in place**, but the "pit", or core, of the bomb had been dislodged and was removed. The United States Army Corps of Engineers purchased a 400 feet (120 m) circular easement over the buried component. The University of North Carolina at Chapel Hill determined the **buried depth of the secondary component to be 180 ± 10 feet** (54.9 ± 3.0 m).
>
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Naturally my understanding of building nuclear weapons is minute but I seem to recall reading that one of the harder parts is enriching the fissile materials. Since the fissile materials in a field in North Carolina are present that hurdle is overcome. It seems to me that a determined party could purchase land near the site and tunnel to the fissile materials. After all people were able to tunnel to a depth of over 200 feet on [Oak Island](https://en.wikipedia.org/wiki/Oak_Island_mystery#Triton_Alliance_(1967%E2%80%931990s)) so the flooding here should be manageable with enough determination.
Assuming:
* The fissile materials are still present
* A tunnel can be constructed to allow the removal of the fissile materials
* This is a secret project so we can't do things that would clearly tip off the government.
* We're working out of a farm.
Could someone who has a PhD in nuclear physics build a functioning nuclear bomb using the 50+ year old fissile material buried in North Carolina? Or would they need additional controlled items like [tritium](https://en.wikipedia.org/wiki/Tritium) and [deuterium](https://en.wikipedia.org/wiki/Deuterium) that wouldn't be present to build anything more than a dirty bomb?
[Answer]
The key is to re read the description of what was removed and what was left.
The "pit" is the core of the fission device, which provides the energy to trigger the fusion reaction in the second stage. It is an actual fission bomb in of itself (although extremely miniaturized and not in its own weapons casing, once removed from the thermonuclear bomb it is just the "physics package" and would have to be repurposed to make a weapon).
The second stage of a [thermonuclear weapon](https://infogalactic.com/info/Thermonuclear_weapon) is the Lithium Hydrate fusion fuel. The intense x ray radiation and flood of neutrons focused by the hohlraum provides the conditions to initiate the fusion reaction. Interestingly, there is often a plutonium "Spark Plug" in the centre of the fusion fuel. It will only go critical under the intense conditions created by the triggering of the primary.
[](https://i.stack.imgur.com/h5YRT.png)
*Possible layout of a thermonuclear weapon. The spherical part may have been what was removed, leaving the rest behind*
The last part made of Uranium is the "tamper" or "pusher", which is generally made of depleted uranium. Its primary job is to hold the flood of radiation and contain the device for the critical microseconds while the fusion reactions are initiated in the second stage fuel. If it is a uranium tamper, as hinted at in the quote, then it also can fission by receiving the flood of high energy neutrons released by the primary. This is the third stage of a thermonuclear weapon, and can provide a great deal of the energy release. The "[Tsar Bomba](https://infogalactic.com/info/Tsar_Bomba)" used a lead tamper, because it was calculated the use of a uranium tamper would have *doubled* the yield to 100MT. The bomber barely made its escape with a 50MT blast, and extensive damage was created hundreds of kilometres from the explosion as it was, so dropping the uranium tamper was probably the smartest course of action.
So if you were to somehow salvage the remains of the nuclear weapon from its hole, you would potentially recover a subcritical mass of plutonium and a depleted uranium casing used for the tamper. Neither will be sufficient to build your own nuclear weapon, either fission or thermonuclear.
[Answer]
At first blush, I'd say no, and probably for different reasons than you'd think.
Nuclear physicists are a smart lot, for sure. However, building a nuclear weapon requires a lot more knowledge than just an understanding of how the fissile material reacts and breaks down. You need a whole host of technical and engineering knowledge and skill since you can't just look this stuff up online. Your average Ph.D. probably doesn't have the means or expertise to design and fabricate everything else needed for this project. You can't buy bomb parts at Home Depot or Grainger.
Consider the [Manhattan Project](https://en.wikipedia.org/wiki/Manhattan_Project#Organization). It had, among other things, a force of military engineers and technically-skilled personnel in addition to the civilian scientists. Even with all of that, many parts of the project were contracted out to be fabricated (which your lone rogue scientist can't do). Granted, they were trying to figure this all out from first principles, but you're going to have to do the same if you don't want the FBI and the military finding out.
TL;DR there's much more needed to make a bomb than just the fissile materials, and that information isn't going to be readily available.
[Answer]
Even assuming you had the fissile material (you wouldn't), it's not just an issue of materials, but of precision in putting them together. In even the simplest nuke several hundred incredibly precise actions must occur with sub-1/1000th of an inch tolerances and within microseconds of each other. There is no way you can get the materials, specialized components, and precision machines without spending hundreds of millions of dollars and setting off alarm bells in 3 letter agencies from the FBI to MI6.
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help).
Closed 6 years ago.
[Improve this question](/posts/99195/edit)
Obviously I'm not looking for practicality, but more curious if it would work. If mice(or something else small) classically conditioned to press a button when they saw a certain light or heard a certain sound, would you be able to make a simple computing device out of them?
How much information could you train a mice to memorize? How many Light/button combinations could you teach it before you'd need another one? A bit? A Byte?
What technology would all need not to be present in the setting for this to be a wee bit practical?
[Answer]
Yes, it would not necessarily be very good, and it would likely not be digital, but there is no reason that such a computer could not be built. Animals may not be very reliable, and they may drop dead at unfortunate moments, but so do computers - admittedly, the more animals you have the less reliable you can expect things to be, overall, but something does not have to be very reliable to be useful - think of early weather reporting - nor does it have to be reliable at all, to be considered by a lot of people to be useful (think of horoscopes), sometimes just the novelty (the newest new thing) is enough to get people either using it, or enthusing about it.
As I said, it would likely not be digital, but could be very good at fuzzy thinking and pattern matching. A lot of modern computing is actually based around recognising significant patterns and taking actions accordingly. The trick is to reduce problems to patterns to be matched. Patterns could probably be best matched across the workforce, who of course would all need to be fed (think Bites, rather than Bytes), although some motivation other than food would be needed to drive the actual processing. It needs to be carefully thought through, but I believe it would be possible.
<https://en.wikipedia.org/wiki/Pattern_matching>
The main obstacle, as I see it, would be designing a method of data storage and retrieval - I have no idea how that could be done, but I expect some imaginative person could think of a way, or a method of obviating the necessity.
I would suggest using small animals, such as [ants](http://www.nature.com/news/2010/101209/full/news.2010.662.html), rather than larger animals, like mice. I would also suggest reading Douglas Adams, 'The Hitchhikers Guide to the Galaxy'.
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No.
"Never work with small children or animals," is a quite well known quote in show business, as animals do not consistently react to stimulus. You cannot rely on multiple such animals in a system to give reliable results; it takes just one of them acting out to cause a glitch.
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Its possible, but not very plausible.
Animals have been used as targeting computers in experimental torpedo guidance systems during the world wars to great effect. However, advances in other technologies made them obsolete before they could ever be put into use.
Before the silicon transistor, there were mechanical computers. Switches were flippers by motors, gears, and actuators. I think the most you could reliably incorporate animals into the picture would be to have them power a mechanical linkage computer by running in wheels as the motors.
The instant you have electricity in the picture, it's possible to make a way more efficient computer.
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I understand there are a lot of factors to consider here, but would it be possible for material from the ship's destruction to fall to earth and cause significant damage to a city? What is a reasonable amount of time to pass for the debris from the destruction to hit the Earth's surface?
It is relevant that the ship was built by humans and in the far future, but the material, size, and manner of destruction are irrelevant as long as it is possible for debris from its destruction to hit Earth. Basically I need to know if it is possible for the ship to be destroyed in some way and in a fairly tight time frame (minutes to days, not months to years) have debris hit the Earth's surface.
Material, Size, manner of destruction, as well as orbital altitude can all be modified to achieve the desired outcome.
[Answer]
Let us consider what happened when a large man-made orbiter did fall to earth.
<http://www.history.com/news/the-day-skylab-crashed-to-earth-facts-about-the-first-u-s-space-stations-re-entry>
>
> On July 11, 1979, with Skylab rapidly descending from orbit, engineers
> fired the station’s booster rockets, sending it into a tumble they
> hoped would bring it down in the Indian Ocean. They were close. While
> large chunks did go into the ocean, parts of the space station also
> littered populated areas of western Australia. Fortunately, no one was
> injured....
>
>
>
> Mocking NASA’s inability to say precisely where Skylab would land, entrepreneurs across the country sold T-shirts emblazoned with large bullseyes. Another enterprising individual took a different tack and sold cans of “Skylab repellent.” Few people felt reassured by NASA’s statement that the risk of human injury from the event was just “one in 152.”
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A lot of Skylab pieces showered Australia. Some are collected in a museum there. Here is the biggest piece: an oxygen tank weighing about a ton.
from <https://www.space.com/21122-skylab-space-station-remains-museum.html>
[](https://i.stack.imgur.com/1VZcx.jpg)
So: if little Skylab can shower the earth with 1 ton pieces, your huge ship could definitely do the same.
A caveat as regards destruction: Having a big wad of metal fall on you will mush you, but your falling ship will not wreak dinosaur-killer scale havoc. Pieces falling out of orbit [are moving at approximately 270 miles per hour](https://www.theatlantic.com/technology/archive/2011/09/the-strange-tale-of-the-skylabs-fall-from-orbit/245332/) when they hit: that is terminal velocity and will be true regardless of the mass of the falling piece, That is true also for meteorites less than 10 tons which slow down in the atmosphere then fall at terminal velocity.
Big 10 ton+ meterorites have too much kinetic energy to slow all the way down. They can hit at speeds of 5000 miles per hour or (much) more. F = mv^2 and so these things are what make the huge craters.
<https://www.amsmeteors.org/fireballs/faqf/#12>
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Strictly speaking, the answer is "Yes, that can happen." However, there are so many ways that it could happen that the full scope of "how" would be too broad.
Since you don't need the full scope, but rather need only a few good ideas, I will offer some.
1. During an explosion, pieces are going to be generally accelerated in all directions. If the explosion is strong enough, you can decide that sufficient acceleration has occurred on the debris to make it go in whatever direction you want.
2. During the explosion, perhaps one of the rockets was actively thrusting at that moment, or maybe it is thrusting in reaction to the explosion to help stabilize; either way, that rocket, and any arbitrarily large chunk(s) of the ship attached to it, break away because of the reduced structural integrity. This piece(s) could now be essentially a missile and could happen to randomly land wherever you want. This might be your best bet.
3. You said "in low earth orbit," but is it actually *orbiting* at that height? Similar to the answer from @AndreiROM if this is a new ship, or not new but is currently being moved from planet-to-orbit or orbit-to-planet, and it is being hauled up or down on a space elevator then all you need is for an accident where the elevator breaks or the ship breaks off it or similar. This would allow the entire structure to fall almost straight down if it's only at LEO altitude. A little bit more altitude and you could have it fall in an arc away from the elevator location. This would probably be the fastest option and would provide you with whatever time frame you wanted depending on the altitude the accident happened at: minutes, hours, days, even months or years... whatever you want, just change the altitude accordingly.
Of course, you can combine multiple ideas together. Perhaps a large shower of debris over a large area and a rocketing piece or two to specific locations.
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Unless it has additional force added, anything in LEO will eventually fall back to earth. There is enough atmospheric drag to cause it to slow down.
For a really good description of Low Earth Orbit, see [What’s So Special About Low Earth Orbit?](https://www.wired.com/2015/09/whats-special-low-earth-orbit/)
The question is, where and when will it eventually fall?
See [this](https://www.space.com/37370-cubesat-deorbit-space-junk-experiment.html) for a discussion on de-orbiting time frames.
If you want it AIMED at a city, then the applied force to de-orbit it would have to be precisely calculated and methodically applied. It would have to be a controlled reentry. And even then, it would not be a sure thing. However, the time frame could be in hours, if enough thrust were applied to slow it sufficiently. The orbit would effectively be changed from that of an orbiting object to that of a ballistic object - that is, a parabola, as if it were shot like an ICBM from earth. Their targeting can be very precise, but the applied maneuvering thrusts are very carefully controlled.
In point of fact, when vehicles are returning from the ISS, they are sometimes deliberately placed into a steep parabolic ballistic trajectory from their orbital trajectory. See this [very technical description](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670019592.pdf), complete with graphs, from NASA, for re-entry trajectories. See particularly figure 2 for a 'Skipping reentry trajectory' - basically, puting it into a parabolic trajectory.
However, if you wanted it to accidentally hit a city, then introduce fate into your story. It is highly unpredictable as to where something will fall. The upper atmosphere is highly unpredictable. But the steeper the descent (the more velocity it looses) the quicker and more predictable the impact point. The more like a ballistic (parabolic) trajectory and less like an orbiting (circular) trajectory. The time frame can be anything from a week to decades, depending on the initial orbit and how much atmospheric drag it comes under.
As for the damage it would cause, it also depends on the impact trajectory and angle of approach. However, if it started from a stable low earth orbit, it would not have gained enough energy to be anything greater than a very big accidental localized collision. It would be similar to a similar sized airplane falling to the ground. It might take out several city blocks, and even leave a trail of destruction if the angle of impact were really shallow, but it would not be a city-buster.
***TL;DR***
Think of the impact damage of the planes that hit the World Trade Center. They hit under full throttle, and the towers survived initial impact. Scale up the size of the aircraft to match the size of your generation ship, and you have some idea of the scale of the collision. The speed of the falling space ship would actually be somewhat less than the speed of these planes, since the ship would be under free fall, and the planes were under powered flight. And given that generational ships would probably not be aerodynamically shaped, atmospheric drag would be significantly greater than a plane.
[Answer]
A generation ship is, by its very nature, going to be very big.
Assuming that its structure was largely complete, yes, it would most likely fall to the ground in a giant heap of twisted metal which would cause terrible destruction and devastation.
Of course the manner of its destruction is also very important. If it gets blown into a million pieces its impact on the ground is going to be much smaller, with only a few pieces being large enough to do any real damage (the debris would, however, cause untold chaos in our orbit, perhaps taking out every satellite we have).
If, however, the shipyard somehow lost control of the behemoth while towing it to a new location, for example, and it somehow "slipped" into Earths atmosphere, it would impact the ground like nothing that has ever hit the Earth before.
Depending on the size, it could be capable of causing, if not an extinction level event, at least global devastation (tsunamis, earthquakes, massive fires, not to mention nuclear fuel spills, etc.)
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[Question]
[
>
> **Premise:** Assume that one man has a genetic mutation such that his gametes (sperm) never have an X-chromosome. Unlike most men (who have a roughly 50/50 chance to sire a male or a female child) this man can only sire sons.
>
>
> Assume further that this mutation is 100% hereditary such that every son born to his line will have the same mutation, siring sons.
>
>
>
* How long might it take for officials to notice that something was wrong?
* Under what circumstances would this be declared a problem by the government, such that it might act to stop further procreation?
* What cultural or sociological conditions would increase or decrease the likelihood of detection?
* Is there any plausible scenario in which the result would be catastrophic population collapse in a region or worse?
[Answer]
# How long might it take for officials to notice that something was wrong?
Several years. They would notice that the female to male ratio is going down and would wonder why, but for this to be noticeable it would need to affect at least 2-3% of population. Someone would start suspecting, and looking for, female infanticide. When this does not pan out, they'd start looking for some causes, investigating whether the phenomenon is local or not; there are chemical pollutants that mimic hormone activity and could be the cause of this.
But very soon someone would run a sperm check, the same kind of test that's done to increase the likelihood of male offspring. Or someone with the mutation might ask for *female* offspring - selecting gametes with X chromosome. And the technicians would scratch their heads and say "Sorry sir, you haven't any" and rush to publish their finding.
# Under what circumstances would this be declared a problem by the government, such that it might act to stop further procreation?
Probably not for a long time. The government would declare it a problem, and surely screenings would be made available for those who wanted, but what would be the point of *stopping* procreation? Male children have traditionally been preferred in many countries, so this might not even be seen as a problem by many, and could be regarded as a blessing for some.
On the other hand, from some simplistic simulations I've run, without a working test and some degree of enforcing, either by social pressure or governmental fiat, the population appears to be doomed.
# What cultural or sociological conditions would increase or decrease the likelihood of detection?
Possibly if the country *already* had a male/female imbalance due to a policy such as "only one child for family", combined with a traditional preference for male offspring that had resulted in the disappearing of female fetuses (or even newborns). Then, a mutation that has the same effect would be hidden for longer (one more generation - twenty years? Twenty-five?). But even there, there would be someone wanting females - for example, to join two families - and the truth would emerge.
For the same reason, any sort of detailed sperm check *for whatever reason* would reveal that some guy has no X spermatozoa. Further tests would immediately follow. So any advanced society where genetic screenings are performed (to, say, reduce the risk of conceiving children with genetic syndromes) would see the game discovered in a matter of **days** once an affected individual entered in the tested pool.
Mandatory genetic testing against genetic diseases for everyone would trigger discovery as soon as the first affected individual decided to have children - say some twenty to forty years after the mutation took place at his conception.
# Is there any plausible scenario in which the result would be catastrophic population collapse in a region or worse?
Yes. At first, in absence of tests, the mutation will spread more or less linearly at each generation (assuming the generation size remains constant), and **all** scenarios lead to extinction:
```
48.10% F, 51.60% M, 0.30% X // Linear growth
48.37% F, 50.87% M, 0.76% X
47.78% F, 50.50% M, 1.72% X
48.28% F, 48.80% M, 2.92% X
45.81% F, 48.76% M, 5.43% X
42.63% F, 48.39% M, 8.98% X
42.25% F, 41.55% M, 16.20% X
36.71% F, 35.84% M, 27.45% X // Curve starts to flex
28.99% F, 27.42% M, 43.59% X
19.90% F, 20.39% M, 59.71% X
13.83% F, 13.33% M, 72.84% X
7.84% F, 9.13% M, 83.04% X
4.38% F, 4.97% M, 90.65% X
3.09% F, 2.13% M, 94.78% X
1.76% F, 1.27% M, 96.97% X
0.30% F, 0.30% M, 99.40% X
0.20% F, 0.20% M, 99.60% X
0.00% F, 0.00% M, 100.00% X
Extinction
```
But if we introduce a testing when females are 10% of the population (pretty late if you ask me), which decreases the chances of a fertile "YY" mating to 10% of normal (this takes into account testing errors and people marrying knowing the consequences *and* having children nonetheless):
```
...
14.86% F, 14.78% M, 70.35% X
6.91% F, 8.33% M, 84.75% X : X < 10%, introducing tests
25.64% F, 23.78% M, 50.59% X // Ratio immediately drops
40.08% F, 41.41% M, 18.51% X
49.37% F, 45.63% M, 5.00% X
50.80% F, 48.31% M, 0.88% X // Decrease becomes 1:10
52.61% F, 47.31% M, 0.08% X
48.20% F, 51.80% M, 0.00% X
Mutation dies out
```
Other scenarios see a maximum of two children per couple, and since a viable couple needs one female, the population declines rapidly:
```
49.80% F, 50.10% M, 0.10% X, population 100%
48.80% F, 50.80% M, 0.40% X, population 99%
48.87% F, 50.31% M, 0.82% X, population 97%
52.00% F, 46.32% M, 1.68% X, population 95%
48.68% F, 47.17% M, 4.15% X, population 98%
49.38% F, 44.28% M, 6.34% X, population 96%
40.53% F, 44.63% M, 14.84% X, population 95%
37.27% F, 38.44% M, 24.29% X, population 77%
32.23% F, 28.05% M, 39.72% X, population 57%
24.32% F, 23.24% M, 52.43% X, population 37%
Introducing tests
35.56% F, 40.56% M, 23.89% X, population 18%
49.22% F, 46.88% M, 3.91% X, population 12%
54.76% F, 45.24% M, 0.00% X, population 12%
Mutation dies out
```
If, in addition to tests, a third child is encouraged:
```
...
Introducing tests, maxc=3
42.69% F, 36.26% M, 21.05% X, population 17%
49.77% F, 44.75% M, 5.48% X, population 21%
49.85% F, 48.62% M, 1.53% X, population 32%
54.19% F, 45.81% M, 0.00% X, population 48%
Mutation dies out
```
With a testing of 50% efficacy and a policy of allowing a third child only when population is below threshold, 2 otherwise, the population stabilizes around a 6% of mutations, oscillating between 90% and 130% of threshold.
Of course, real world conditions - people ignoring the tests and/or shirking the children limitations and/or *not* having all the children they can - may shift these results considerably.
[Answer]
If not identified and taken under control this mutation will result in the extinction of the species, especially if it is linked to the Y-chromosome. That is if sexual reproduction is the only option. Genetic engineering and cloning will help to avoid the extinction.
In your suggested scenario, the number of women will start to decline. At first, it will be happening slowly, but as the gene spreads, fewer couples will be having daughters. This will lead to huge social changes (for example, [increase in a number of marriages and their stability](http://www.iflscience.com/brain/men-more-likely-to-marry-when-there-are-fewer-women/)) and possible collapse of the societies (not immediately, of course) since skewed sex ratios favouring males are linked to [social](http://amzn.to/2xospVa) [unrest](http://www.pnas.org/content/103/36/13271.full).
The reaction of governments and societies and when the mutation is noticed will depend on the level of medical science and/or genealogy traditions. Sufficiently advanced societies with the understanding of genetics and developed traditions of preserving and studying family histories would have an advantage. I believe that they will try to find all men with this mutation and sterilise them in order to avoid extinction.
I would also guess that a society that places a high value on sons will make some associations with these men unique ability to produce sons only. They may even see it as an advantage. Although, even those societies would probably eventually start to stigmatise those men.
For the spread of the gene, you need to decide on your setting, fertility rates, marriage patterns, and so on. Without these, any calculations and assumptions can easily go wrong.
[Answer]
There are more than 3 billion men in the world, if a Y+ man has an average of 6 Y+ children (say it has some psychological effects too) it would take 12 generations to get there. Until the last generation the majority of men don't have the gene, so there is more than a hundred (probably more like 300) years to realize we have a problem before solving the source is not good enough. Even once we reach the gender skew in more skewed parts of the world we still have another generation before we would expect normal males (and the species) to be vulnerable to extinction.
But it wouldn't spread that far that fast from a village. In its home village it might cause problems, as many sons might be expected over a few generations to marry into most of the local families. This would then produce a local surplus of males and a dearth of females. At this point scientists might notice and would be interested at the departure from the expected sex ratio at birth.
The village could probably import brides from neighboring places, but as it exports males other nearby communities would also be effected, soon making it clear what is happening. While some cultures might value this on principal marrying foreigners isn't all that common in much of the world, and pretty quickly the drawbacks would become apparent in the original district.
If it gets to a city first things might be a little more interesting. If siblings don't stay close there would be little reason to lump them as a demographic so science would not be interested, anecdotal stories of ten grandsons and no granddaughters are just curiosities. By the time anyone found a larger demographic like a city or region was a couple sigma out of normal the gene would be pretty wide spread, but there would not be immediately clear evidence of the cause. And if you are before computers the tracking required might make finding the cause at all doubtful.
In this case village girls get attracted to cites as the fewer city girls make finding a well off guy virtually guaranteed. But villages won't be able to support the ratio and populations will then decline. As the population in cites declines it gets easier for the villages not yet exposed to the gene to replace missing females in cities, but more villages would have accepted outside males at some point leading to my first course.
Even the densest scientists would see what was happening by the time cities populations decreased, but that is one generation after interference can keep population stable, and more decline is expected before recovery no matter what. Again it would become clear that the gene isn't good and it would be avoided, but this time much of the connected civilization would have been exposed and recovery would need to come from unconnected pockets.
Once the gene is identified it won't really matter long term.
Imagine two groups of people, the Xs and the Ys, the Ys have no females and therefore their population isn't meaningful to the size of the next generation. The Xs need to produce one female for every female in their group, plus one for every female that joins the Ys. This thinking changes the nature of the problem form a gene spreading one to a simple surplus male problem, even if it is renewed from generation to generation. If we end up with a stable population of Xs it doesn't mater how many Ys we have.
The [Fisher Principle](https://en.wikipedia.org/wiki/Fisher%27s_principle) says evolution would be expected to eventually solve it. But humans aren't that pressed, and we could pretty easily cope with a skewed sex ratio, you just might have first world birth rates more like third world ones to keep a stable population with extra males about.
[Answer]
# An Issue With the Premise
You never stated if the gene is passed on to the next generation. This is super important. If it is never passed on, this mutation is odd, but not an issue for society at large.
# Detection
$P(n\_{boys}) = (\frac{106}{200})^{n\_{boys}}$ is the equation that gives [the rough chances](http://www.npr.org/sections/health-shots/2015/03/30/396384911/why-are-more-baby-boys-born-than-girls) of having a family of [only boys](https://youtu.be/3IaYhG11ckA) with $n$ children. For $n=5$, the odds of this happening become a little above 4%! (The odds of two boys in a row- about 28%.)
Adding the odds of children to the mix, and even with two children to each couple, the odds of this happening are a little under **2% after the first 4 grandchildren**. For 3 children each, it's **0.05% after the last grandchild**. I would expect people to wonder about if after the 1st generation has children. (The initial man/wife pair is generation 0.)
This is also assuming that these people live in a society where knowledge of grandparents and cousins is common, and no one is put up for adoption, becomes sterile, dies before their time, and so on.
If [genetic screening](https://www.genome.gov/19516567/faq-about-genetic-testing/) for this gene (or all genes) is available, this theoretically can be caught with the initial man, and potentially contained with his children. Of course, just because we can sequence a genome doesn't mean that we instantly know what those genes do.
# Reactions
We, as a species, seem to be pretty terrible about coming together and doing something for the good of the species. This is especially true if it involves individual sacrifice. Pick a topic, and see how bad humans are at having a single, unified stance: [capitalism](http://s2.quickmeme.com/img/c0/c0f5a11bcd63c904ff40709ebdb34485a1b825350a5c936a9257aa2af8e9999c.jpg), [climate change](https://www.thoughtco.com/cartoons-and-memes-about-climate-change-2734107), [toilet roll facing](https://i.pinimg.com/736x/4e/60/39/4e603939d948cc5544bac1fb438e1fab.jpg), [Kirk vs Picard](https://www.youtube.com/watch?v=OOV6XDtCO5A), etc...
In short, unless the people who want the human species to continue are in charge and can implement a [eugenics program](https://en.wikipedia.org/wiki/Eugenics), this problem will spread, possibly dooming humans.
[Answer]
Most importantly to any consideration, it must be noted that the Female sex is the default sex. That is, unless something specific happens in utero, a female will be produced, irrespective of the presence or absence of the Y chromosome.
The Y chromosome is NOT the only thing that determines the sex of the offspring. There are mammals without the Y chromosome, and they still have males. The human Y chromosome has atrophied to such an extent that it is posited it will eventually disappear. In the same vein, female sex determination is not completely dependent on the absence of the Y chromosome. [Is the Y chromosome all that is required for sex determination?](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658794/)
But there are basically only three ways that a male could produce only Y chromosome gametes.
First method, all of the cells in his body would have to be YY. If so, he would be horribly maladjusted, as the genes on the X chromosome are vital for human survival. Mate selection would be troublesome.
Second method, X and Y gametes are produced normally, and something causes the X gametes to be destroyed (like an immunological reaction). Immunology is not on the Y chromosome, so it would have to be on some other chromosome, which means it would not be 100% passed on. Sperm count, and thus fertility, would be cut in half.
Third method, that X and Y gametes are produced normally, but the X sperm are severely disadvantaged such that the X sperm are unlikely to cause fertilization. Sex selection is already built in to the male sperm, since male Y sperm swim faster but die quicker. This has altered the ratio of male to female births, but has not severely altered it. To be 100% effective, the male sperm would have to me completely nonmotile. Again, effective sperm count and thus fertility would be substantially reduced.
It is hard to envision, under any of these methods, that this mutation would become established in the human population, without substantial help from in vitro fertilization, in which case the process is moot. No need for such a mutation, X sperm would just be screened out, as is done currently.
If you want hard statistics on the societal repercussions of a male birth preference, investigate the research from China. The one-child policy has lead to there being over 30 million more males than females, in just three or four generations, and this was due not to just one male, but to widespread selective abortion and infanticide. The societal implications are substantial and were unforeseen. Unbalanced sex ratios tend to be self-balancing in the end. Males that produce female offspring reliably, in the family background, would become preferred mates.
[Answer]
The first generation - that is, the first person with a YY chromosome.
The Y chromosome is exceedingly small, it has lost 90% of its viable genetic material. See for instance [this](http://www.npr.org/sections/health-shots/2014/07/28/334490208/with-mens-y-chromosome-size-really-may-not-matter)
The Y chromosome has very little genetic material left, and any viable offspring needs the X chromosome genes to survive. A YY baby would have little chance of survival.
In fact, eventually there will be no Y chromosome in the human species.
The good news is, it is not needed to produce a male. It is only a very minor factor in sex determination. Everything else is done by hormones and such.
[Answer]
* How long would it take to be noticed?
That depends where it started. If it started in a society where most families have many children (typically poor or per-industrial societies), it may take a couple of generations to be noticeable. If I have six children - all boys - and my parents and five brothers all have many boys and no girls, it becomes something that is worth medical investigation. Even without modern medicine, after a few generations it would become known that there were some families that only had boys.
On the other hand, in societies where most families have only one or two children, it is not so obvious. If I have two sons and no daughters and so do my parents and brother, it is not a coincidence worth investigating. It is more likely to be discovered when a couple who want a daughter used some type of assisted reproduction technology to try to select their childs sex and discover that there are no X-baring sperm.
* The effects on Society
If nothing was done about it there would be a gender imbalance in the population. When there are excess men with no prospect of marriage and family, it is likely that there would be institutions like the military or monasteries which provide a substitute for the family environment for single men. It is also possible that women would give more priority to child-baring as that "skill" becomes rarer and hence more valuable.
I suspect that the imbalance would be self-correcting or at least self-limiting. If there are many more men than women then women can be more fussy in their choice of partner. Even without genetic testing technology, it will be known which men are from affected families. All else being equal, women will prefer husbands from unaffected families both because they want to have daughters and because they want their sons to be unaffected.
[Answer]
The man without an X chromosome would likely also be sterile.
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[Question]
[
Unlike Humans, the great Apes have feet with an abdicated big toe. This allows them to grasp tree branches and manipulate objects like we do with our hands.
My question is this: If an intelligent, bipedal humanoid retained this feature, what would their shoes look like? Would they even be able to wear them at all?
[Answer]
We already have some kind of shoes (o socks) which have room for individual fingers.
[](https://i.stack.imgur.com/R9ORa.jpg)
I imagine for your imaginary feet they would look like these, with the obvious adaptation of moving the toe on the side.
However, considering how cumbersome is to do precision work with hand wearing gloves, I doubt that ape feet (which are meant to do precision grabbing) and shoes can coexist.
[Answer]
**Thicker padding on the walking surfaces and fingertips.**
[](https://i.stack.imgur.com/nEQZy.png)
When an ape walks (on all fours) these are the surfaces of the back feet in contact with the ground. Your shoes should be a pair of fabric gloves with hard plates on the walking surfaces.
The shoes still do their job, and the fingers/toes can still be used for climbing if necessary.
[Answer]
So as to get a permanent upright twofeeted walking whilst keeping the handly setting, from a speculative evolution perspective, I recommend to lengthen and strengthen the metatarsal bones and become the apes or any other unmannish primate lineage into metatarsigrade walkers, right like the birds and other theropod dinosaurs, but only when they themselves are on the ground; otherwise, when they're on a bough or hanging from a bough, they'll be plantigrade walkers. That's how my sophont lemurs's feet are. I also happened to design Romanly sandals for my lemurs's feet, which have individual slots for the toes, and are full of adjustable straps: 3 straps for each toe, 2 straps for the feet's rest, and 2 more wrappings for the ankles. These sandals's paddings are thin yet sturdy and bendsome, akin to the mannish “barefoot shoes”, since they must still enable delicate toe movements for handling little objects.
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[Question]
[
I'm currently writing a sci-fi trilogy on an alien world with a CO2 and methane atmosphere. The natives have pottery but since fires cannot work on the planet, how would they harden the clay without heat of any kind?
Would say using an element like mercury be a possibility to leech the water from the clay to harden it?
The aliens are methane breathers and they eat hydrogen peroxide (in addition to carbon from plants and animals) for their metabolism- there's perchlorates in the water as well.They have a primitive technology- living in tribal areas.
Any ideas welcome!
[Answer]
"cooking" the pottery is not done only for taking away the water. For that sun drying would be more than sufficient, but it is well know that sun dried pottery is way worse than fire cooked pottery.
By raising the temperature during the cooking you also allow chemical reactions to take place, transforming the silicates and other compounds into the pottery and make the material become more resistant.
Though they may lack fire, they might still have other heat sources, namely volcanic or radioactive areas, which are not fire dependent.
[Answer]
If you have mercury; you have a lens: Put it in a dish and provide a low spin, it will form into a parabolic lens that focuses sunlight. Large lens = hot hot focal point. The dish can actually be just dried non-porous clay. The focal point can be a built up rock, brick or dried clay oven, up on some platform above the lens, and the bottom of this oven can have a small hole in it so the focal point of the lens heats a rock that won't melt, but can get to many hundreds of degrees.
Other ways to focus the sun will work too, if you can polish anything to a reflective surface. I know you don't have glass for lenses (because you don't have the heat to make glass!) but as a note IRL arrays of glass lenses can focus the Sun to a point with enough heat to melt iron. It is just a matter of size.
The same will be true for parabolic reflective lenses; check out these Real-Life [Solar Power Towers.](https://en.wikipedia.org/wiki/Solar_power_tower) A spinning dish of mercury cannot be oriented to track the sun. But given a reflective surface (which does not have to be image perfect smooth; just reflect most light), made of polished silver or [other reflective metals](http://nvlpubs.nist.gov/nistpubs/bulletin/07/nbsbulletinv7n2p197_A2b.pdf), this same idea can work on a very small scale: Reflect a lot of light to an oven on a tall stand (made of some wood equivalent or if need be a stone tower with clay mortar), and it will heat up. Put enough light on it, and it can get as hot as a forge, help refine metals, create crucible steel, etc.
Trial and error will tell (or have told) your aliens which rocks, materials, and clay recipes can tolerate the heat.
[Answer]
Add a naturally occurring resin to the clay before forming. You can buy clay with a plastic resin that hardens in contact with air. I bought some a couple of weeks ago
[Air Dying Clay](https://www.bunnings.com.au/boyle-500g-white-air-dry-clay_p1882914)
[Answer]
Its sand melting and binding ? So without heat and liquifying these elements- how to get the sand to bind?
Other sources of heat it is then:
So, possible are solar furnaces - light focused to heat up ceramics.
Geothermal vents- basically use lava to produce cook pots.
Other chemical reactions.. Metall fires are possible even without oxygen. Other chemical reactions can produce similar heat.
Finally, pyhsical trickery, like standing waves heat production:
<https://link.springer.com/article/10.1007/s44189-023-00023-x>
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[Question]
[
So we humans get big into genetic modification and figure out how to make ourselves photosynthesize through our skin, and somehow it generates enough energy to be worth our while. Obviously we'd still need to eat, but adding sunlight to our diet is pretty cool. Let's assume we all get this modification.
Now... **What would our clothing look like after this change has occurred, what type of materials (real or fiction) would they be made of? Would be just be naked when we could?**
I'd like the focus to be on clothing design and materials, but societal concerns about decency should be considered.
[Answer]
If genetic modification gets going as radical as adding photosynthesis decency is long gone. You could add fur, or make everything interesting retractable, or have enough [diversity](https://travel.stackexchange.com/questions/99199/how-can-dark-skinned-travellers-deal-with-unwanted-harassment-from-locals-in-chi) that traditionally interesting stuff is the least interesting stuff around.
To make photosynthesis work you need area. It is [suggested](https://gardening.stackexchange.com/questions/1433/how-large-a-cultivation-area-to-feed-one-person) that at least 100 square meters of crops are needed to feed a person. It is [suggested](https://en.wikipedia.org/wiki/Trophic_level#Biomass_transfer_efficiency) that ten times as much energy is required to make a food source than the eater receives, so let's guess you need at least 10 square meters of photosynthesis to power a human directly. A human typically has [less than](https://en.wikipedia.org/wiki/Body_surface_area#Average_values) 2 square meters of skin.
So if all our skin (even the soles of our feet) was used in direct sunlight for making energy it would not work out all the way. So we need leaves to increase our surface area without adding a lot of mass we have to feed, or we need to keep eating, or we need to become a lot more efficient.
If you add leaves, you need clothing that doesn't interfere with them, and probably the leaves need to be retractable (10sqm is a parking space). Possibly clothing helping support the leaves in the extended or retracted position would be nice, or you could hang interesting things off them. The leaves might also cover any parts you don't want to display reducing modesty clothing without giving up modesty.
If we eat we can just eat more when we wear clothing over some fraction of our skin. We can wear whatever we want if we have enough to eat. Leading to normal clothing, just getting skimpier the less you want to eat.
If we are more efficient we probably end up cold blooded, so don't need clothing, but we have to avoid places that are too cold. (They probably don't have good sun anyway) Or we slow down. Either way a similar trade off as eating, the less clothes you wear the less you have to use the other strategy.
If you change photosynthesis to use a non-visible part of sunlight (IR or UV) you could have normal looking clothes made of materials transparent to those frequencies.
And [real humans](https://en.wikipedia.org/wiki/Yaghan_people#Early_Yaghan_people) are able to do largely without clothes even in cold places.
[Answer]
Define "decency". I've lived through 2 fashion periods where women's nipples were visible thru their blouses or dresses and even today many women choose tops so that their nipples protrude. Same thing for guys and tight pants, some men chose them so that the outline of their penis is readily visible.
Either you are very young, extremely oblivious, or both as far as current events go. Women not wearing a burqa have been arrested and even stoned top death. Similarly in New York City, the laws covering nudity (last I heard) make *no* distinction between men and women. Anywhere where it is legal for men to be shirtless, it is legal for women as well.
And anyone with even a poor education knows that some hunter/gather cultures tolerate complete nudity (especially in children). So, it is ridiculous to ask about cultural absolutes as far as nudity.
My *guess* is that a culture should tolerate only exposure of skin which is sanitary - that is doesn't significantly spread "germs". Both sweat and waste from the anus, urethra, and vagina (as well as (lactating) breast leakage) would be expected from nearly all healthy individuals. Fluids from unhealthy or injured individuals also needs to be considered. Given our (current) anatomy, it seems to me that in an environment where temperatures (winds, humidity, sand, pollution, UV,...) don't require protection, then a loincloth would be a minimum.
However it seems to me that there's almost no advantage to having photosynthetic skin in the groin, armpits, inner thighs or soles. To be effective, the photosynthetic skin will be more vulnerable than skin might be without it. Although I can think of several tropical plants with very tough leaves, in general the surfaces of leaves are not very robust. So, like everything else, any redesign of human skin and metabolism will have both advantages and disadvantages.
One (obvious) function of modern clothing is moisture control. Seems to me that we might be able to have moisture permeable, colored clothing which only slightly filters light in the blue to orange part of the spectrum (violet and red colors would take out the least energy). Thickness would matter: thicker, greener clothing would be a status symbol, as would multiple layers.
Hair would be counterproductive, but sunglasses (or modified eyes) would be useful. I should mention that obviously someone living at the North Pole would have different optimal trade-offs than someone living at the Equator, similarly someone living in a city or rainforest compare to living in the desert.
[Answer]
I'm going to look at this a bit differently. Since a human being or even a large animal like a cow does not have the surface area to effectively photosynthesize, the genetic modifications would essentially increase the surface area by at least an order of magnitude (while even this might not be enough, since traditional agriculture often requires at least 1/4 acre of land area to feed one person, we can always handwave that additional genetic tweaking has increased the efficiency of photosynthesis from its current 1% to between 5-10% of the catered energy).
In order to have enough surface area, the "photoanimal" might be covered in leaves resembling pine needles.
[](https://i.stack.imgur.com/2a9GK.jpg)
*The new you*
This covering would be similar to a coating of long, coarse fur, which would effectively cover the various openings and sensitive areas of the body.
Going further. a "photoanimal" would be somewhat symbiotic. The "waste products" of the plant part could be directly absorbed into the bloodstream of the animal part, and the waste of the animal part would be absorbed by the "roots" of the plant part. A photoanimal would have radically different designs for things like guts, lungs, kidneys and so on. This means that you might not even find an analogue for an anus or a mouth on a photoanimal, or it would be in a very different place and serve a different function (scooping up dirt to add micronutrients for the plant, for example).
The most radical design might be making a human symbiotic to a "hyperplant" with large leaves as a means of existing in free space. The hyperplant could not only gather sunlight and convert human wastes back into oxygen and carbohydrates, but even act as a solar sail for propulsion. The human part of the hyperplant would steer between NEO's to gather water and micronutrients which have leaked out of the closed loop ecosystem established by the human/hyperplant symbiont.
[](https://i.stack.imgur.com/RfBOE.jpg)
*Human/hyperplant in orbit*
In either case, the amount of light gathering surface (the leaves) of the photoanimal or human plant symbiont would effectively *be* the clothing, or at least covering, of the creature.
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I do not believe we would see any substantial change in clothing due to this.
Most clothing is worn for warmth and photosynthesis will not yield nearly the energy that would be needed to compensate for the lack of insulation. Even when it's not needed for warmth it's often needed for other protective purposes. The amount of time someone actually could dispense with the clothing is low.
As for the other part of the question--"decency", there is no absolute standard of decency. **Most** societies say that the reproductive and eliminatory organs and the female nipple be covered. Some go far beyond this, some grant exemptions for nursing mothers, some western societies have decreed that requiring the female nipple to be covered is sexist and that the same standard must apply to men and women. Some tropical societies also do not require the covering of the female breast. One society has no problem with the penis so long as it is tied up with a string, but a loose penis is indecent.
I have traveled in many third world locations, I have seen plenty of bare breasts that were obviously socially acceptable, I have seen plenty of naked preschoolers, I have seen full adult female nudity whose acceptability was uncertain. (There were nearby guards {soldiers, not rent-a-cops} that would in all probability have at least thrown her out had they known of her presence, thus it was impossible to know what her apparent fear was of. Our best guess was that she had nothing and had slipped in to get some warmth from our fire--she did not strike us as a crazy and that level of poverty wouldn't be out of the question given the situation. She did not respond to any language our group could muster so we don't know the details.)
Thus what is "decent"?? Expect most societies to adapt to what is practical.
If somehow the photosynthesis created enough energy to matter I would expect that the law would change to basically reflect nudist standards--your genital/eliminatory organs are not to touch common surfaces. This very well might be implemented as requiring a garment equivalent to underwear, although I could also see the nudist towel standard being adopted.
[Answer]
If we could engineer photosynthesis capable skin and still want to preserve decency and yet need to live lives not entirely spent sunbathing, then we'd need batteries. Maybe convert under garments and clothes into rechargeable batteries which when worn negate the need to sun bathe all day.
Alternatively if we must photosynthesise as we go about our day then clothes would have to be a combination of tiny mirrors and anti glare screen attachments which reduce the viewing angle of a pc (anti eavesdropping) fashion then becomes not a way to attract attention but rather a means to facilitate life.
This wouldn't fly for too long as the more artistic among us would need to self express and we'd crave a way to differentiate ourselves to potential mates. Entire masses would thus try the 'beggar my neighbour' policy but on an individual level.
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Settings: In a Fantasy setup, different factions face up for the control of the subterranean territories they live in. One of the 4 factions is the Government (Human race not including the tribal people) and is basically a medieval society almost achieving steam engine level of technology. The Government is led by **the Elite 4 composed of 4 representatives of each class (Inquisitors, Scholars, Workers, Soldiers)**.
The way I would want the Elite 4 to be chosen is simple: Whoever in each class has the most points. **One gets 1 point for each citizen voting for you** and **accomplishing small or great deeds will award a certain number of points** (a scholar making a breakthrough in science, a soldier surviving many battles, an inquisitor proving many people to be heretics...)
To avoid everyone voting for himself, say we implement a minimum point threshold to enter the elections.
If enough people vote against a class leader, no matter his point score, he will be dismissed and the next in score will take his place.
The technology level is close to steam engine, but there are remains of the surfacean's technology that they think of as magic (Nanotechnology that is voice controlled. Not anyone can wield them and only a few fist-sized orbs of nanomachines have been discovered).
---
**Now my problem!**
**We cannot really expect a book to just contain any single possible deed and its point value**
=> The book would soon be outdated by the scholar scientific advances
=> New threats could rise and their defeat reward for soldiers wouldn't be recorded in the book
**Very specific situations could rise and just following the book wouldn't be enough.**
so how can I describe this system? What means could I use to evaluate any deeds achieved in order to keep the Elite 4 a "fair" meritocracy?
---
Feel free to ask more questions (about the other factions or the setting or how the "magic" works).
By "Medieval" I meant a society where religion still has a strong political power.
Farmers work the field for a lord (Veteran soldier or Inquisitor. Scholars are fed by the tax on the lords' harvests to the Curatorium) or in the machine rooms/labs for the scholars.
---
Edit: Separatrix exposed a big flaw in this setting. I'll try to reformulate my story in a new question. Thanks to everyone who helped on this matter.
[Answer]
You're going to trigger a cultural problem, that of the importance of being *seen to do* over actually *doing*.
Let's consider two people
* One is a young man of no great resource, he helps little old ladies across the road, works in a soup kitchen during his holidays and helps his elderly neighbours with chores they can't handle any more. There's no question that he's a good chap at heart and does what he can to make the world a better place. It's mostly invisible work for invisible people though, nobody (important) knows he does it and it's not going to be recorded in the great book of deeds.
* The other is a wealthy self publicist. He doesn't move without a media circus and wouldn't give a penny to a beggar without at least a dozen people standing round to see him do it. His good deeds might be minor and of no consequence to his available resources but he uses those resources to make sure they're seen and recorded.
The second man here is going to have a lot more base points against his name before standing in the election. It's a standard case of paying the piper for the tune and your system is going to be very vulnerable to it.
There's a second factor between these two candidates, that of available resources.
* The first gives most of his free time to do small things directly for the people in immediate need, his resources are small, his effect is small, but that effect is disproportionately large relative to those resources.
* The second has vast resources, he could give millions to charity, without discomforting himself in any way, and help vast numbers of people, but that effect is disproportionately small relative to his resources, he is capable of so much more.
This means they must be judged subjectively based on their capacity for great deeds, not just on their actions.
*Batman is a greater hero than Superman, because Batman puts his life on the line every time he goes out. Superman for the same actions, would not be in personal danger.*
To gain equivalent credit under a fair system, the person with greater resources or greater ability must achieve proportionately greater effect.
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[Question]
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**I'm designing an alien species and I want the males to have deer-like antlers.** Now I also need this species to have a **genetic predisposition** (as in it is not just a cultural affectation) to be **primarily monogamous** (as their progeny require a lot of attention/effort much like human larvae).
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Of course since antlers in the real world are used by stags to attract mates and "defend" (mostly symbolically as they aren't actually that useful to harm opposition) their **harems** from other males the two traits I want are at first glance **incompatible**.
There are potential solutions to this problem however. The first, probably most obvious answer is to find a utility other than that of male compitition for my creatures' antlers that is somehow **exclusive to males**. I really can't think of any possible usefulness that would **only apply to males** though.
The second resolution that I have considered would be that monogamy is a relatively recent evolutionary development in the species that I want to create and thus that the antlers are **vestigial**. This would of course mean however that larger antlers would gradually be **selected against**, quickly leading to stags **without any antlers** at all (there are conditions which can cause a stag to be born unable to ever grow antlers without even needing successive mutations in the real world). Approximately how long would it take for most males to not have antlers?
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My main question is this: *Would it be realistic for the majority of the males within a primarily monogamous species to have antlers?*
[Answer]
The antlers can be a signal of health, a strong immune system, etc, just like a peacock's tail. The peacock's tail is actually a drag on survivability (literally), it makes it more difficult for the peacock to escape predators (and this is observed in the wild). The same has been shown for bright colors in other male birds; it reduces camouflage compared to the female's drabber brown to black feathering: The latter evolved because color in a female is unnecessary (or vice versa).
For a peacock, we know females are attracted to larger tails and symmetric tails, and avoid males with missing feathers or lop-sided development; which may be a sign of disease or other fitness failures in escaping predators, which would reduce the likelihood of chick survival. (The females don't know that, of course, they are just genetically predisposed to attraction to large, symmetric, colorful tails).
For antlers, demand the same thing: large, symmetric, unbroken, and uniform in color and visible texture. No patchiness, no thinness. The male has to be healthy with plenty of calories to spare to carry such a rack. It does not have to be that they FIGHT with it; just like peacock's do not fight with their tails.
Even if they are an intelligent species like humans, it won't matter: Human men and women both are still very much predisposed to the physical characteristics of healthy individuals: Models are almost always very close to perfectly symmetrical in face and body; women are attracted to tall men with deeper voices, men are attracted to young fit women. Everybody prefers smooth skin that has no hint of disease. Your antler species will be the same, no matter how "intelligent" they may be, attraction is at a much more instinctive animal level in the brain than rational thought is likely to be.
[Answer]
Skew the reproductive process to slightly favor male offspring, thus creating a relative shortage of females and thereby allowing the females to be selective in their choosing a mate.
Then make big antlers attractive to those females either as a symbol of virility or because some other positive trait (strength, intelligence, longevity,...) is proportionally linked to antler size.
This would allow the vestigial antlers to resist the pull of natural selection, despite their no longer having any survival-assisting functionality of their own.
[Answer]
They look like antlers, but really, they're antennae.
If we can avoid the whole "fight for a harem" angle we eliminate a lot of unpleasant implications. You could, for example, say:
The bone in your species' antlers is laced with fine traces of gold, making them highly sensitive to electromagnetic radiation. This provides a competitive advantage - e.g. either in finding food or avoiding predators - that females find valuable.
Why do we only find them on males? Perhaps they have a downside as well. If antlers make you visible to predators, whatever sex is caring for the young may not benefit from them, while those who can stand and fight are better off.
[Answer]
/relatively recent evolutionary development in the species/
Consider a circumstance where males and females (the latter with young) have different feeding methods / patterns. This is the case for giraffes, elephants and a range of other animals. It keeps males from competing with females and young for food.
Now your creatures. The antlers are likely one of a package of secondary sex characteristcs left over. Imagine the antlered males have different feeding habits that require the same hormonal environment that causes the antlers - maybe they need bigger more muscular jaws to crack the fruit, or their foraging requires upper body strength to upend rocks etc. Maybe the males with more male secondary sex characteristics are better killers and catch meat, enriching their own diet and that of their family. Antlerless males that look like females can of course move in and live like females and maybe this is happening with your species to some degree. That might be fine or it might disadvantage the male's own offspring because of increased use of historically "female" food resources / non-use of historically "male" food resources. The low hormone male will have reduced fitness and this trait will not spread.
If there remains a selective advantage (different food resources) for the males using their secondary sex characteristics to forage in the old way, the antlers could remain as a holdover. Selecting against antlers means selecting against the entire package.
Another possibility is that secondary sex characteristics, antlers and aggression usually used for intra-male mate competition might also be useful against predators. I am thinking of baboons. Male baboons will team up to drive off a leopard or similar predator. If having males with secondary sex characteristics mean you lose fewer infants to leopards, selection will keep them around.
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My world has lots of civilizations which, due to geography, have little access to the kind of sea travel as a means for trade, exploration, and conquest. I think the people of this world may be driven to explore air travel as an alternative. However, I know that airplanes and balloons are "modern" technology, and tend to use modern synthetic materials that ancient peoples wouldn't have had access to. So my question is which of the materials that ancient peoples had access to would work best for building air vehicles, and could they construct entire fleets this way? What would be the practical limitations on their use of this technology?
I'm working with the assumption that these cultures have basic understandings of the principles of buoyancy, and have at least some access to gasses like helium and hydrogen thru magic/alchemy. I am most interested in the construction of the air vessels themselves, such as the balloon envelope which has to be a fine enough fabric to keep gas from leaking out, or the rigid skeletons of zeppelins and airplanes.
[Answer]
Unmanned hot air balloons are popular in Chinese history. Zhuge Liang of the Shu Han kingdom, in the Three Kingdoms era (c. AD 220-280) used airborne lanterns for military signaling. These lanterns are known as Kongming lanterns (孔明灯).
It has been [demonstrated](https://web.archive.org/web/20110714201319/http://www.nott.com/Pages/projects.php) that manned hot air balloons can be built using ancient materials like those available to Nazca civilization (smoked cotton fabric for the balloon and reed for the gondola).
[Answer]
Silk makes great hot air balloons as it is light weight and super strong. The practical limitation is going to be silk production. Silkworms are fussy creatures. You'll need forests of mulberry trees just to feed them. You need lots of cocoons just to make one plied thread. The keyword is sericulture.
Production of silk goes back to ancient times in China.
[Answer]
There are a few materials you could use, silk being one.
If silk isn't appropriate, leather may be an option, it's waay heavier however it's a much more accessible material if you have the craftmanship and can cut it thin enough.
Also, helium is a poor choice for filling it, seeing as if you get a puncture or something it'll be a pain to refill, hot air would be a much better choice (hence - Hot Air Balloon)
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I have this shapeshifting alien living on earth posing as human. He does not follow any "alien agenda", just trying to blend in to ensure his survival. He has a wife, children, stable job etc. Never does anything unhuman-like. Now he is about to be exposed.
**How could humans (preferably his own wife) possibly find out about him?**
Important thing is, he knows this is about to happen **before** it actually happens, but he is **powerless** - or maybe not motivated enough - to do anything about it. Could be some mistake he made that is too late to fix.
Here is some more information that might help:
* This guy is way older than Earth itself, he has been living here since before humanity, posing as different people/animals, faking aging and death every time.
* He can simulate human organism (or any organic/inorganic matter) down to molecular level. It takes less than a second for him to change form and he does not do it often, only when he is about to assume a new identity for another 60 years or so. Last time he did it was decades ago
* His kids are completely human, anything alien that was ever in them was a single simulated sperm cell.
* He is the only one of his kind, nothing like him ever existed.
* He is of above average, but still humanly intelligent. Very experienced with pretty much everything because of his age.
* He is totally capable of being killed (albeit harder than regular humans), only thing that ensured his long age before and on Earth are his unmatched survival skills. (Not sure if this is relevant to the question)
* There are about 5 to 10 other immortal beings on Earth (superpowered humans, not aliens) that knew about him, but forgot a long time ago. Besides them, everybody that ever knew about him (human or alien) is long dead.
* This takes place on present-day Earth. No alien-detecting technology has been developed and wil not be for some time.
* He does get exposed from time to time (once in about 1000 years on average). When this happens, he fakes his death and changes identity again.
* He did live on other planets before Earth, left only when given civilization went extinct or drove him away
[Answer]
You could put him in a life or death situation where he and his wife and children are trapped and the ONLY way to survive would be to shape-shift into something that could handle the situation.
## POSSIBLE SITUATIONS
* Forest fire and cut off from rescue: The only way out is by air, he knows that the only way to get his family out is to shape-shift into a gigantic bird and fly out with his family on his back, or something like that.
* Trapped in rising flood waters: He needs to shape shift into either a boat or an animal that can get them all out.
* Home invasion: Well armed intruders are going to kill his family if he doesn't do something.
Take a situation like any of the above where his options for anything else are slowly being taken away, one by one, so that his ONLY remaining option is to shape-shift of lose his family. This approach will allow you to build dramatic tension.
Take the fire for example. They know it's closing in, so first, they try to drive out, but the roads are blocked, then they try to radio for help, but high winds make an air rescue impossible. Things get more and more desperate as he looks for any other way to keep from revealing his secret, until finally, there is no other way.
Make him very fearful of doing so. Perhaps a back story of another wife in the past who was so repulsed by knowing she had been with a monster that she ran off, or killed herself, or, worse killed their children out of fear of them being monsters too. Make the stakes VERY high for him.
[Answer]
## Blood samples
He was recently involved in a health incident of some sort. Possibly an accident, or a sudden bout of illness, or similar. During this time, when he was unconscious/delirious, well meaning health workers took blood samples for testing. These blood samples will remain human for a while outside his body - a couple of days, a week, perhaps - but soon will revert to his natural state. At that point, the jig is definitely Up.
## Illness
Similar to above, but instead of blood samples, he has contracted some kind of illness - even something simple, like chicken pox - which is interfering with his ability to maintain his shape. He knows that this is happening, but there's nothing he can do to wipe out he virus. In x-time, his shapeshifting ability will be temporarily suppressed, but definitely long enough for his wife to find out the Truth.
## Blackmail
For a nastier version, perhaps someone is threatening his wife and children if he doesn't "Tell the truth". The blackmailer doesn't even need to know what the truth is - they could be talking about his business dealings, or have tracked an earlier identity and realised he's not who he says he is. But if he doesn't "tell the truth", the blackmailer will harm his children, or expose his secret.
[Answer]
I say there HAS to be something different about him. Otherwise, the instant he turned into a human so fully and completely that he could have a completely human son, he would essentially BE human, not alien. He could never change again.
You need to create some subtle difference--perhaps the blood mentioned above, that distinguishes him from a human.
Also, I find it a bit unrealistic that he could live millions of years without dying somewhere along the way. I would think you would need some kind of resurrection system. That's just my humble opinion.
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[Question]
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This is a series of maps of Old World empires:
[](https://i.stack.imgur.com/OqGOC.jpg)
[](https://i.stack.imgur.com/L7BHQ.gif)
[](https://i.stack.imgur.com/aW2he.jpg)
And now look at the pre-Columbian New World empires:
[](https://i.stack.imgur.com/2n5aC.jpg)
[](https://i.stack.imgur.com/2LpN1.gif)
[](https://i.stack.imgur.com/tdHT3.jpg)
We're not 100% sure why Old World empires were so huge and New World empires so small, but a good guess is that the Old World took advantage of a mammal called *Equus ferus*--the horse. Horses had been used as draft animals, long-distance carriers and war weapons.
The horse used to be a triumph of New World evolution, but the Younger Dryas climate chaos 13,000-11,000 years ago drove the Western Horse into extinction, so the horse could not be a source of New World cavalry. The Younger Dryas also drove to extinction another American originality--the camel.
In this alternate history scenario, the Younger Dryas still happened, and it still drove the American horses into extinction, antelopes--real and pronghorn--never existed, but camels still thrived in North America. Questions follow:
* Would the Native Americans still view them as food, or would they be domesticated just like horses?
* Would camel cavalry change the very foundation of Native American culture? If yes, then to what extent?
[Answer]
[Camel cavalry](https://en.wikipedia.org/wiki/Camel_cavalry) has been employed many times in the past, with one of the best known being used by Muhammad and his followers, who conquered much of the Arab peninsula using them. While camels have some disadvantage as cavalry, (they aren't quite as fast as horses and their swinging gait makes it difficult to fire arrows from camelback), which is why historically they have mainly been restricted to use in desert climates (and occasionally to specifically counter horse cavalry; horses who were unaccustomed to camels would often flee at the sight of them), they are still a heavy, fast animal that people can ride for long distances and charge enemies with. In the absence of horses, it is quite likely that camels would become a primary cavalry animal.
If the absence of the horse is indeed the reason why New World empires did not expand to the same extent as Old World ones, it is likely that the presence of camels would change its history significantly.
[Answer]
**Genghis Khan** had horses, he also had the vast Asian step on which to ride them, but look at that southern border where it traces round the edge of the Indian Subcontinent. Mountains.
**Alexander** had horses and ships, he travelled round the Mediterranean and out as far as the Indian Subcontinent then he stopped at almost exactly the same border as the Golden Horde, at the mountains. Also his northern border at Armenia, mountains.
The **Romans** were a Mediterranean and coastal empire. All roads might lead to Rome, but it's quicker by boat, their inland penetration from the coasts is relatively limited compared to the others.
Now take a look at the geography round the American empires, they have that same limiting feature, they're stuck in the mountains. They just hit their mountains a lot sooner, a lot closer to home. If they'd crossed the mountains then they'd have hit the rain forest, also not an environment suited to fast travel. There'd be potential for a North American empire with horses, again across the plains, but South America is a dead loss until you can cross the mountains and clear the forest.
Camels are going to be no better at crossing those mountains than horses. Transport is not a limiting factor until you can actually get out onto the plains.
[Answer]
Empire requires
1: Intensive agriculture
2: Central authority
3: Surplus population
Intensive agriculture requires draft animals and one could make the case that a draft animal like a camel would be much more helpful than the use of a camel as a war animal.
Some cultures did not have intensive agriculture for lack of suitable crops (e.g. Australian aborigines). Maize is definitely suitable for intensive agriculture, and potatoes too, both of which are now grown worldwide with the help of draft animals. So why no draft animals? One reads that Native American animals like buffalo and moose are not tamable (like African elephants and Cape buffalo). But it is hard for me to understand why the Incas did not use llamas to pull plows. Not strong enough? Why didn't the Mound builders use elk? I suspect neither of these is a strong, tractable and optimal draft animal like an ox or a donkey and the energy of activation was to much. In circumstances where people were familiar with draft animals like oxen they might be motivated to try other animals, like a water buffalo. But like anything else: if you have never seen it done maybe you would not think of it?
One other thing about empire: these preindustrial eurasian empires consolidated advanced, resource rich civilizations. These empires did not incorporate the Scythians or subsaharan Africa because there were not advanced civilizations there and so the profit from conquest was not worth the effort to do it and the ongoing effort of administration. If those people had something the empires wanted they could get it via trade.
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In the setting I'm creating for a game, I've given one of the factions plasma shielding and I'm about to rewrite the code behind their shields from scratch. I wanted to revise the game mechanics to be more in line with how the implemented technologies would behave in the real world.
I'm not quite going to make a 100% realistic space combat game, but I wanted to make sure everything behaved mostly in line with how they would in the real world. If something turns out to be impractical following real world rules, I may just make it impractical in the setting.
The shields in question work by taking the exhaust plasma produced by the ship's fusion reactor(s) and ejecting them around the hull while creating a magnetic field to keep the plasma contained in a shell around the ship. Even without the plasma, the magnetic field is able to protect the pilot/crew from cosmic radiation. The plasma is there to protect from incoming projectiles.
Questions:
* Would the magnetic field required to contain the plasma around the ship have any adverse effects on the pilot/crew and other components of the vessel? Would the ship/pilot/crew need any shielding against this? (fun bit of irony in shielding against your own shields)
* What would the shield look like? Or would it not be visible? Would the pilot/crew be able to see through this shield without some sort of assistance from the ship's computer?
* Would the energy draw be independent on incoming damage? Or could the shields be pushed by too much damage?
* Would the ship need to spend any energy to prevent the plasma from cooling in space?
* How much would the shield alter the aerodynamics of an aircraft flying through atmosphere?
How would the shields interact with the following projectiles? Would any of these projectiles completely ignore the shield? Would certain ones be rendered useless against shields? Would some of them be able to partially bypass the shield?
* High velocity bullets/slugs
* Guided and unguided missiles
* Focused electromagnetic waves
* High power lasers
* Plasma based projectiles
I sincerely apologize. There were a lot more questions than I was intending to ask that came up while I was typing this post. If any moderators believe there are too many questions for one post, I can try to split this into a second post.
[Answer]
**All depends on the temperature of the plasma**
Fusion plasma can be heated to millions of kelvins. This would be destructive to material projectiles, but would cool extremely fast. It would radiate energy outwards (shining like sun), and inwards (heating the spacecraft skin, and overloading it's thermal management) If your fusion engine is not an absolute torch-drive, and your fuel mass is not high, I don't expect, that such a shield could be sustained for a reasonable time.
Plasma is known for being able to absorb or reflect electromagnetic radiation:
<https://en.wikipedia.org/wiki/Plasma_stealth>
Therefore a plasma shield could defend the craft against electromagnetic radiation. (including lasers) But the usual frequency, below which a plasma is reflective, is normally much lower then that of visible light or x-ray (which could be used in a laser weapon.) To effectively counter laser attacks, much more denser plasmas are needed.
It is very difficult to confine plasma with magnetic fields, even when the magnets can surround the plasma (like in a fusion reactor). So, I expect, that a lot of particles will leak, and will be constantly supplied. If the enemy weapon fire gets absorbed in the plasma, it will heat up. If the equilibrium temperature is too high, its particles can acquire so much velocity, that they leave the magnetic confinement, and the shields gets blown away.
A fully deployed high-temperature plasma shield would saturate the passive EM sensors of the vessel, and only let trough active scans, which have higher frequency, than its Characteristic electron plasma frequency. You want this to be high, since you want to reflect lasers, so the shield would render the ship almost blind.
**The only really feasible option seems to be a not-too dense, not-too warm plasma cloud.** This could be used for radar stealth, but won't mean effective defence against the most attacks. But at least, it could be sustained, without loosing too much plasma or energy.
For game, I suggest, that plasma shield would have a long charging time, while plasma is building up in a magnetic bottle, which have extremely reflective supermaterial wall too. The more reduce engine thrust, the faster it accumulates, and the more energy you divert to heating lasers, the warmer it gets. In the critical point, it is discharged in a spectacular flash. Depending on its temperature, it would last for some seconds, fully countering EM attacks, and reducing kinetic damage by 4/5. If enough EM attack is recived, it would last a little longer. It causes some bearable thermal damage to the ship.
EDIT: plasma shield vs plasma projectile
I'm a bit skeptical about plasma weaponry. Radiative cooling would mean quite a problem here too, and if the plasma is jut fired from its magnetic cannon, it would dissipate in every direction quickly. But if they solve this by the magnetic fields induced by the currents flowing in the plasma projectile itself, and make a viable short range weapon, some interesting mechanisms might arise.
The effect of such a projectile on the shield would be very variable. Depending on how the confinement fields of the shield and the projectile relate to each other, almost anything can happen. Might the projectile is slowed down, and merges with the shield, making it stronger. Might it gets repelled, and dissipated in the void. Might it cuts trough and hits. A lot of computer simulation, scientific research and spywork would be needed to determine the field configurations of the enemy plasma cannons, and find out the ideal shield magnet configurations to counter them.
Even in battle there is some field for creativity. The shield confinement probably would have poles and stronger areas. So the effect would depend on, what part of the spaceship faces the enemy, when you fire up the shields.
EDIT2:
In some extreme situations (like enemy ship grappling us and trying to board) the High-Energy Plasma Flare Shield could be used as offensive weapon too. (If the enemy hull intersects the main volume of the shield, shield discharge could burn it and cause EM damage too.)
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It sounds like the sort of idea the Chief Engineer would pull out of a hat to get the Star Trek crew out of a jam, then never be mentioned again even though it worked so well. You may need to devise reasons why it can't simply be used again and again.
Set some rules as a game mechanic, both strengths and weaknesses so the plasma shields work like Rock-Paper-Scissors. It beats some attacks, but is vulnerable to others.
Based on your description, here are some possible mechanics:
* The ship's regular shields are electromagnetic. This requires power to keep them running. The power level might drop when you use other power-intensive technologies like firing electrical weapons or accelerating.
* Venting excess plasma from the engines implies you need to wait for the excess to build up. You can't use this defense too often or you actually start to deplete plasma you need to travel/escape.
* the plasma has it's own electromagnetic properties. Aligned with the magnetic shields effectively makes the shields stronger while using the same amount of power, but at a cost to maneuverability. If it can block particle weapons and missiles, your thrusters will not push against the outside world.
* Alternately, the plasma has it's own electromagnetic properties and you must use more power to the shields to hold it in place.
* The plasma shield is so strong conventional weapons are not only destroyed on contact but they are actually drawn to the shield, thus the shield can clear an area of incoming missiles – however, this works both ways: you cannnot shoot out through the shields and your own projectile weapons can be drawn back to you.
* Once you release the plasma, it explodes. Holding it in a coherent bubble with your shields only delays the explosion, so once shields drop you'll need to move away quickly from the plasma cloud. This might require you to drop your regular shields to stop dragging the plasma with you.
[One of the first discussions I read on Worldbuilding was about shields](https://worldbuilding.stackexchange.com/questions/65720/shields-at-10-one-more-hit-and-what), and the answers provide many ideas for how shields might work and the problems they might have.
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From popular fiction, I think the idea of a Space Whale fairly well defined. Dozens of kilometres from stem to stern, an ecosystem for many creatures in and of itself, undertaking millennia long migrations from system to system, yada yada - you probably get the picture.
In the course of this this creature's life, it'll encounter incredibly variable conditions (the interstellar void, relatively dense protoplanetary regions, energy-rich expanses over massive stars, the homes of whatever it uses to feed, etc), - and as it goes through different conditions, it'll physiologically shift to adapt to its surroundings. Given how space is a pretty wild place, I'd imagine purely shifting from one predefined state to another probably wouldn't cut it, and some more continual adaptive approach would be needed.
**The question:**
How on a physiological could this creature pull this off?
What would be required for changes within the creature itself to occur in response to unpredicted situations?
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# Space Whales are comprised of Zooids
[Zooids](https://en.wikipedia.org/wiki/Zooid) are single animals that form part of a larger animal - the larger animal being in effect a colony.
So, your space whale would contain many different kinds of zooids that perform specific functions and have a [particular skill-set](http://www.imdb.com/title/tt0936501/).
So, when your whale needs to move, more propulsion zooids are created and deployed. For feeding, others are created, and so on. You end up with a dynamic adaptation of the whole animal depend on its needs.
[](https://i.stack.imgur.com/8mlj2.jpg)
[Source](http://ocean.si.edu/ocean-photos/jellyfish-or-siphonophore-colony) - Siphonophore zooids forming a jellyfish.
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What you're talking about isn't evolution. Evolution, by definition, occurs over an entire species as individuals with a greater capacity to survive are able to reproduce.
An organism could have evolved to adapt to *specific* changes in its environment, provided its ancestors experienced those changes frequently, but they cannot innovate new changes. Some fish can change from fresh water to salt water physiology, for example, because their ancestors lived in a changing environment where being able to adapt to both environments was beneficial and therefore the ones who had that ability *already* passed it on to their children. But an individual from such a species cannot spontaneously develop the ability to live in acid if their species has never needed to before.
The only adaptation that is capable of making *new innovations* within a single individual's lifespan is **intelligence** - in fact, this is the whole point of intelligence. It is thought to be the reason why octopuses, a non-social species, are relatively intelligent - they live in complex, unpredictably changing environments where being able to adapt to new food sources and avoid new predators is important. (Social animals also often develop intelligence because they live in a complex, changing environment consisting of *other members of their own species*.)
For an organism to physically change its body in response to novel circumstances, it would need to have *conscious control* over almost every aspect of its physiology, from its chemistry to its body structure.
In space, raw materials are rare but (if you're close to a star) energy can be abundant. It may be worthwhile for a space creature to be intelligent, as it can use sunlight to power its brain, and will need to calculate precise trajectories in order to propel itself to new food sources, which will be used mainly to acquire the mass it needs for reproduction. It may also cannibalize parts of its own body to acquire precious mass, and could choose to grow new limbs in different ways. This process *would* use a lot of energy, so it should do so only when it is near a star.
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Magic is just another skill, like welding or juggling, that can be learned and mastered by just about anyone. However, this is not widely known because spells require a lengthy build-up before being cast.
Anything is possible with magic (absolutely anything) but the bigger the physical change to the real world, the more magic 'potential' energy is required before casting.
**Scenario**
Evil warlord assumes control of a small city state by walking into town and obliterating the governor's office with a wave of his hand. Everybody flips out and surrenders to his power, because nobody knows that it took 6 weeks of meditation and intense concentration to store enough energy to case that spell. Beyond fear, and the implication of a repeat incident, how does the man keep his position of power and prevent people from realising he's really quite puny and not much threat?
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**He doesn't need to keep power through magical means.** You said that the threat of another destructive incident is enough to keep the people subdued for a time so that is a good place to start. If he is a warlord, the sorcerer surely has followers already so the best thing to do would be installing them in positions of power in the city. If he has a stranglehold on guards, food, money and other necessary resources, he's already won. If there are any swordsmen or warriors, creating an oppressive force similar to a city watch should be enough to quash any rebellions.
After this transition phase has passed, fear really won't be necessary to keep commoners in line. Historically, as long as they're left alone, they don't care who is ruling. The main rebellious class will be the highborn who were in charge previously. If you still want to do it without magic, simply exiling from the city them will work for a time. No upper class, no upper class rebellion. Otherwise, turning a few to the sorcerer's cause, perhaps with promises of wealth or more power, will give him spies with which to keep control. It is hard to plan an uprising when any of your co-conspirators will rat you out.
**A rotating set of mages could keep meditating for magic to be used when needed.** If it takes six weeks to gain enough power to obliterate a building, but most people don't know this, then the intricacies of magic don't seem to be widely known in your world. In this case, three or four mages under the warlords control, by alternating who mediates and when, could keep a small city in line. Even if the warlord is not one of the mages, he would still have at least one mage with a fortnight of power stored. Depending on how much this is worth in your world, a fortnight's worth of power could be more than enough to remind people of the warlord's power. This way, you can conceal the weakness of magic's long charge time.
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## Dictatorship
It seems unlikely that he is the only one who knows how magic works, so he needs to create a dictatorship of sorts with other trusted mages and keep a tight grip on the city because someone else will definitely meditate long enough to explode him.
Just like Serenical said you could have a set of rotating mages and you could even train more mages to protect your dictatorship and instill fear in the people. You can accomplish this by regularly arresting people that speak badly of you, censor media and art, and other stuff that dictators do.
## Stable Dictatorship
You could also try to take a different approach by promising people you will protect them and saying you will bring them wealth and power with your magic, and if you don't trust your people enough you can have some mages meditate in the meantime to cast a large spell to control the people and make them think you're a great leader.
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## Brainwash people
Brainwash knights to be completely loyal to you and protect you with the sword.
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If anything is possible with magic I agree that brainwashing is your best bet.
Or, if "anything is possible" only means physical changes:
Use your magic to cause very small "physical change", which still is immediately fatal. For example: Letting a bloodvessel in their head explode, or stopping their hearth.
But I think this kinda circumvents your system of "slow" magic. I think you have to change the rules a bit. For example: Magic can not directly affect other living beings, or it takes alot of "energy" to go through their innate protection.
Edit: It also seems unrealistic that a citystate would not atleast have one mage themselfes. That mage doesn't have to share the "trick" with anyone. But he would defend the city with his own stored up power, or could even tell the townsguard: "I have supressed his magic, he can't do much now, kill him!"
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Sounds like an interesting idea, why not have a set of spells you can apply different skills to, like long casting, or overload casting.
You can cast a wind spell that becomes a storm with overload casting, or a wind that blows for days with long casting.
That way you can plan a strategy with long casting spells, and use normal casting for getting you there.
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The Lorting are a very strange race. Not only are there multiple genders (the actual term for which is more like 'castes' or 'classes'), but when any member of their species is 'born' it is born at it's full size with exactly the same configuration and number of cells as its peers (similar to Tardigrades). All Lorting have incredibly similar genetic code, much closer than humans.
Some of the castes are capable of 'giving birth', and any other caste (including other breeding castes) can induce a pregnancy with the potential outcome in gender being determined by the combination of parents (in the same manner as some bacteria). Asexual or homosexual reproduction is not possible.
The castes of the Lorting capable of birthing may be smaller than the largest caste they need to give birth to, so rather than internal gestation or laying eggs they instead create a biological substrate onto which they 'print' (though it's actually far more complex than that) the child. This substrate is attached to a solid surface and can maintain the child for short periods while the parent feeds. Not only that but multiple Lorting can (if they've recently 'given birth' to the right caste) work on the same child as the substrate maintains their genetic integrity.
The question is what set of circumstances could possibly give such a species an evolutionary advantage leading to the selection of such strange and complex behaviour?
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**Extremely hostile environments and scary predators.**
Look at marsupials. They produce very very tiny offspring but keep them outside their body. The offspring remain in the pouch until they're capable of fending for themselves fairly well. If the food supply runs out or disaster strikes they simply abandon the offspring and cut their losses.
So, your species develop their young in some kind of a chrysalis external to themselves which they can connect to to nourish. That could be a more extreme version but not too crazy.
Make the environment extremely hostile with predators which can easily kill anything less than a full size adult so they need to come out full size.
Pregnant individuals would also suffer too much from being slowed down.
The chrysalis is placed somewhere remote/high/barren/hidden and multiple adults help feed it, perhaps family, perhaps other adults the parents have made deals with each other to feed it until grown and if predators find the chrysalis before it's grown they abandon it.
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If multiple of your creatures can work on the same "child" they could be faster at "giving birth". This could come in handy when you think about different seasons. Normally there is a certain time for animals to become pregnant, so that they and their offspring can survive the pregnancy and the first year. For example there has to be enough food.
The size is very strange... Maybe this way they can adapt their society to a fast changing environment, so that sometimes they need many large and strong individuals and sometimes they need a small number of little individuals. Again I am thinking about food.
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### Very short life expectancy
It is possible that your creature's reproduction method has its root in evolutionary past during a far more dangerous time. Back when they were more primitive they tended to die at a rather young age, whether it was from a hostile environment, hostile/hungry predators to lack of food. As a result they needed to be fully capable of reproducing as soon as they were born, after all they might not live that long. Lastly, since they tended to die rather easily having multiple adults capable of working on growing a child is beneficial since it provided redundancy in case one of them dies.
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This is a fine scheme for a high SF concept. It is very close to what actually happens in several scenarios. There are 2 strategies for offspring: many offspring, each with a minimal investment of resources by parents (like barnacles or dandelions) or few offspring, each with a big investment, like humans or coconuts. For example of the latter consider collective breeding where the resources of many related animals are devoted to one or more offspring; mole rats, wolves, humans do that. Consider the maximal resource investiment: matriphagy scenarios where the hatchlings feed on the body of the mother. Scenarios like salmon where the entire generation of parents dies after laying eggs, their decaying bodies feeding the invertebrates that will feed the new generation.
Your described scenario is actually pretty close to that of social insects. Many closely related individuals belonging to several castes team up to raise the young. In the case of a young queen, more resources are necessary and it is very much the "imprinting" you describe: special food and attention produces a queen.
For your story this could be very cool: the human observers note the activity and efforts to raise new, extra large, extra resource intensive individuals. At the end they realize that these are the new queens, which means this species is entering the population expansion phase - possibly with consequences for the humans.
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If the wealthiest people disappeared, how would that effect the economy and the political landscape? What would be the social impact of such an event? ( I also Should clarify that the wealth and all their money, heirs, and belongings go with them [If they owned a house it would disappear])
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## Nothing positive
Economics is a tricky thing to understand and, especially when you're World-Building, can be difficult if you intend to balance the books. Taking our current world and removing the top 1% financially would do more harm than good; especially if that money completely vanishes from the system.
Also, determining how your 1% is calculated can cause difficulties, for example, would you call someone who owns a £350,000 house, no kids, no mortgage and owns a fairly old car within the top 1%? How about someone with a £1,000,000 house, a £500,000 mortgage on said property, three kids and a fairly new sports car?
Western doctrine would state that the latter of the two is more likely towards that top 1% even though, in contrast to the former, he is in fact, poorer by far.
The way our current financial policy works (or at least is supposed to work) is that the more money someone earns, the more taxes they have to pay.
This money is then re-distributed in the form of Government Spending to various companies, who then use the money to sell and buy goods and give people their wages. (and thus, completing the circle here)
The goods can be bought from either government (again, returning the money back to the completed circle) or on to other companies who make the goods, which repeats the cycle above.
Each element of this cycle isn't perfect, as current companies like to maximize profits and so, a little bit of the money is taken out each time as pure profit, but thankfully, this money eventually makes its way back in when the person earning said profit goes and buys personal items; houses, cars, etc.
Now, while taking out the top 1% of earners would seem to be good, in fact it destabilizes this circle, all of a sudden you've just lost approximately 85% - 90% of the money in the world ([FITA Estimate](http://wiki.c2.com/?FingerInTheAirEstimate))
All of those taxes levied on the super-rich; or at least, the ones who contribute the most to our tax system, would be lost. The cycle of funding would grind to a halt as more pressure to pay for said services would fall on those poorest, raising the poverty line (An arbitrary line that many say is the absolute minimum a person can earn in order to be able to sustain themselves)
Massive tax levies lead to inflation, which if left unchecked, leads to hyper-inflation; which is **BAD**.
You might recognize this as familiar; it's happened before in pre-Soviet Russia, although the money never disappeared, but it might as well have; we ended up with a communist state, a cold war and nuclear tension so high we had an acronym for it, MAD; Mutually Assured Destruction.
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1% is a lot of people. Furthermore these people are not uniformly distributed, rich countries would lose a lot more than 1% of their populations.
The threshold is only $770000 according to <http://www.investopedia.com/articles/personal-finance/050615/are-you-top-one-percent-world.asp>
So you would be losing your business leaders, political leaders and top professionals.
So you have a major emergency (nearly a hundred million people just disappearing) and the people who would normally provide leadership in such a situation also disappearing.
The big question is would the people who are left cooperate with each other to try and form a government that could hold the mass-panic at bay and pass laws to allow for emergency administration of companies whose major shareholders and board of directors had gone missing.
Or would the power vacuum lead to massive infighting and war.
I expect the answer would vary a lot by country.
Even in places where the situation was handled peacefully I think it would take a long time for things to get back to normal. Eventually the people would be moved to "missing presumed dead" status and their assets would be passed on to whoever was set to inherit them.
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I'll agree with Raisus and say, "Nothing positive."
The top 1% of wealthiest people works out to 70+ million people at the moment, and while they may not be the top 1% most productive people on the planet (I'm sure that quite a few got their wealth via inheritance and/or government favors), they are certainly concentrated at the top end of the productivity scale.
More importantly, they are concentrated in the management levels of the economy (whether in or out of government), and so the economy of the richest nations will suffer a catastrophic setback.
You are also going to lose every autocrat on Earth and most of the their hangers-on; they have all used their power to put themselves well into the 1%.
You will also lose the top tier of our entertainment industry (the top musical acts, top movie stars, and top sports stars).
So in the freer nations the management of the economy is suddenly cratered (not good), in the non-free nations the top level of government has just be taken out (which sounds good, but), leading to acute instability (which is not good), and a whole lot of wanna-bes in the entertainment industry will finally get their chance at stardom (which may or may not be good).
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It depends on whether the family members of the wealthy are included in the 1%. Does the billionaire's wife and children, who, perhaps, have no income of their own, count as the 1%, or as unemployed with no assets?
If the latter, then they'll inherit everything, becoming the new 1%.
If the former, then the type of wealth becomes an issue.
If the wealth is all cash, it'll remain in the bank, which will reissue it in the form of loans to the public, and eventually deposit it in the state exchequer. No real change.
As shares/stock, with no heir, the corporations will either suspend voting rights and dividends, until an heir comes forward; or again, it will be claimed by the government (unlikely). Again, bar the initial shock, business as usual.
If it is landed property/ gold bullion, etc., the property will simply lie there until eventually, the government eventually, seizes it and auctions it off to bring it back into the economy. Again, no change.
Stuff like this has happened multiple times throughout history, whether it was plagues, natural disasters, revolution or invasions; though, admittedly, never on this scale. Society has survived, often without major upheaval. Consider the French Revolution: while they were executing aristocrats in Paris, farmers were going to their fields as usual.
Even if the wealth disappeared, what would it consist of? Most personal wealth these days, is investments and intellectual property. Does the entire investment vanish, or just the paperwork? Does every copy of Star Wars vanish with George Lucas, every iPhone with Tim Cook, every Trump Hotel with Donald? It isn't solely their investment, there are hundreds of other investors, most of whom AREN'T in the 1%. About the only things that should vanish is their personal wealth, and any personal property, and in commodity terms, that's a few sheets of paper, houses, and vehicles. In terms of actual value to the economy those are negligible.
What would be lost of real value is the individuals' skills/talents, but that would happen when they eventually died. As always, someone else would step up.
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Nothing special will happen.
The people in the 1%-2% bracket will suddenly becomes the top 1% with all the advantages and disadvantages that come with it.
People fail to understand that wealth is really relative.
If the top 1% dies, the fanciest villas in the world would become the property of the 1%-2% bracket etc...
A mediaval king was litteraly the wealthiest and most powerful person in his kingdom yet he was living in a shitty rocky castle with no TV,computer or internet. He was eating good food but probably not as good as a 2 star restaurant. He would have 0 hygiene and medical support and probably die at 50 of some common disaese if he didn t die in a fight before. What I mean is that you probably woundn't want to exchange your lifestyle with his.
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As long as their wealth does not go away with them (their houses, air planes, boats, enterprises, etc.) **nothing special** will happen at all.
The 1% don't comprise the people keeping our society really running (the engineers and scientists, the adminstration clerks and medical doctory, the public service workers). They include some entrepreneurs and some top mangagers that will be replaced by other qualified persons, that's all.
Nothing special also means that the wealth distribution will not change substantially by this happening; it will be just different people being the new 1%.
P.S. Think of this: Also the members of the 1% die, and there is continous replacement happening every year.
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I am aware of the square-cube law, so what conditions do I need for this to work ? The tortoise will be a similar size to the isle of Wight and will walk around in shallow areas in the ocean. What conditions do I need for this to be feasible without magic? I am aware of other questions about similar things such as oceanic creatures swimming underwater and turtles, but I believe this is different as tortoises do not swim fully submerged and are not turtles and would as I propose walk rather than swim. What I believe is the main question is what limits in size are there as the tortoise would be half an submerged walking with its head above the water.
Finally the question is what conditions do I need, not magical ,to have the tortoises proposed?
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**magic or an equal amount of handwavium**
using real world physics its limbs would need to be bigger than its body to support its weight.
the important thing to remember is as you increase size the mass increases by the cube (the volume) while the strength of the bone only increase by the square (the cross sectional area). so you have to make the bones progressively thicker to withstand the forces.
You mentioned the square cube law but I don't think you grasp what it means. At a certain point the increase in bone creates more mass and thus requires more strength than the actual strength it creates.
And that is before you take into account things like surface area of the lungs, getting rid of body heat, or the blood pressure created by "water" column height.
Your best bet might be to not explain it and just make it your acceptable break from reality.
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The turtle's bones are infused with an element far heavier and more dense than calcium and are made up of tiny triangles in a lattice pattern (perhaps crystalline?). Allowing the structure to support more weight with less mass. The turtle's blood has a high alcohol (or some other liquid) making it thinner and easier for the creature's heart to pump. This also has an "anti-freeze" effect, allowing it to more efficiently retain heat. Still, it sunbathes most of the day and moves very slowly due to its low metabolism.
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Since you only specified 'no magic', here's **the sci-fi solution: Have a turtoise cyborg**.
A 'thin' layer of organic matter (flesh, blood, ceratin, etc.) that covers the actual metal body. There's nothing else that would be able to support a multi-kilometer-sized body - no bone matter can be made strong enough to span such distances, no matter how much hard science you throw at them. Have the fusion / fission reactors cooled by the sea water, and you cover the problem of heat development. You will need some kind of blood, oxygen exchange, and glucose intake to keep the 'thin' (I'd expect a meter or two) organic layer alive, but that can be hidden within the metallic body.
And since you do not have to make the turtle cyborg interior solid, it should have some buyoancy, kind of like a ship. Maybe even enough to be able to support itself on the sea surface once it lifts its legs (which would be more like anchors only, not supporting any weight but tying the turtle cyborg ship down). A nice side effect would be that it can't just dive below the sea surface, washing away any and all vegetation that has started growing on its huge turtoise shell.
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**Turtles, no. Big, living/growing, slightly-mobile floating islands, maybe.**
I don't think you can get there with Turtles, per se. However,
*if what you want are big/huge, living/growing islands -- that may be doable with only modest amounts of handwavium.*
1. Compound organisms, working together, can build structures that dwarf any individual member and survive many times the longest-lived individual. A key example are the polyps that create coral:
<https://en.wikipedia.org/wiki/Coral>
2. Some seaweeds form substantial drifts or rafts, when the conditions are right, as in the Sargasso Sea: <https://en.wikipedia.org/wiki/Sargasso_Sea#Ecology> [http://www.seaweed.ie/sargassum/sargasso.php](https://en.wikipedia.org/wiki/Sargasso_Sea#Ecology)
{With a minimum of handwavium, I conjure or} Posit a hybrid lifeform, like Euglena:
<https://en.wikipedia.org/wiki/Euglena>
in that it can both photosynthesize, consume food, and move about in the water. Now, further posit that these have mutated, so that they:
(a) Create durable, buoyant structures (biological syntactic foam) as part of their bodies, much like diatoms -- but with cellulose walls enclosing methane.
(b) Form colonies, for mutual assistance staying in the sunlight. These colonies grow into hexagonal 'rafts' of up to 10-meter diameters, before specializing further. At the raft stage, they have only very limited feeding and mobility, but they do very well keeping afloat and in the sun.
(c) Successful rafts begin to differentiate, forming structural ribs to survive storms, and streamers (much like jellyfish of your nightmares) for improved feeding and mobility. Fully differentiated islands have been observed up to TBD kilometers. Xeno-genetic analysis of debris from two of the larger islands observed in the !@#$%^ survey indicated tissues up to 700 earth standard years old.
The thickened ribs surrounding the individual 'rafts' result in a turtle-shell appearance (and topography) of the islands. Durable, floating coral-like colonies -- except that they can feed themselves on unwary sea creatures that venture too close. Unclear whether they have defenses against surface predators....
I leave the rest of the creature design to you.
Have fun!
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It looks like a tortoise, but is built very differently. It’s mostly a hollow facade of tissue forming the floating mass. The legs have neutral boyancy and are more like anchoring cables: a larger apparent diameter is a protective sheath that creates a suitable environment for the “rope” but it is all hollow. To walk the anchor line crawls forward using a small benthic body serving the foot while allowing the line to slack, then pulls itself forward by tightening the line. The anchor lines are in *tension*, not in compression like normal legs we know.
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You want a giant tortoise that is screwed over by the Square Cube law if I understood your question correctly? Well I have numerous propositions for your.
No. 1: **The turtles live in an environment with enough Oxygen to sustain gargantuan-sized life forms**. The bigger an organism gets, the harder the heart needs to pump in order to get oxygen to every cell in the body (if I am not mistaken). So maybe you could increase the amount of Oxygen within the water, Or you could say that their hearts are more efficient at pumping oxygen throughout their bodies (or you can handwave and say that they don't need oxygen)
No. 2: **The Turtles are nanotechnologically enhanced**. Okay here me out on this one. WIthin the Nanotech community there's a thing called a Respirocyte. A Respirocyte is essentially a artificial blood cell which can store up to 236 times more Oxygen than a regular blood cell can.
<https://en.wikipedia.org/wiki/Respirocyte>
<https://www.foresight.org/Nanomedicine/Respirocytes.html>
<https://www.youtube.com/watch?v=WzGKlVZtQs0>
No. 3: ***The turtles are robots meant to confuse biologists*** This one is pretty much self explanatory.
Anyway I hope you enjoyed my answer!
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# Bones and lungs
In order to support such a large and heavy animal, you'll need enormous and strong bones. Calcium bones would not be strong enough so you'll need something else, probably carbon fiber.
The inner structure of the bones will probably be hollow to reduce weight and latticed to increase strength. You can use this hollow space to house all or part of the respiratory system.
Additionally, this allows you to have a breathing system similar to that of birds, where air is constantly flowing in a single direction, this solves a potential issue that in-out breathing might cause, stagnation.
This kills a few birds with a single stone:
* You solve the issue of getting oxygen to the entire body since now you can have the tortoise breathe from multiple parts.
* You solve the problem of managing internal heat by having the bones act as a cooling mechanism powered by the air that is breathed.
* You use most of the otherwise empty space that the bones will generate
* You solve the whole "breathing" issue
* The air-filled bones help the animal stay afloat in water.
# Circulatory system
You'll probably need more than one heart to pump the blood of such a large creature. The blood itself probably accounts for a large fraction of the weight of the animal, so it's gonna be a difficult task.
One idea I can think of is, instead of having a distinct heart or hearts, make the blood vessels able to pump blood themselves. Having regular one-way valves in the tubes, and constricting muscles around them will probably work, the blood vessels will pulsate in a sequence that will move the blood around.
This distributes the workload to the entire system and solves the slight tendency of water to create vacuums above the 10m mark.
# Muscles
This is probably the most difficult part, moving such a large creature. Muscles will probably make up most of the weight of the tortoise just because of the sheer amount of strength needed to move it. Being partly submerged will help ease the load of actually having to hold up the animal, but it makes moving much more difficult since water is so dense and viscous compared to air.
# Food
Have it eat algae. Even better is if you have it grow its own food. Algae need water and sunlight to grow, the tortoise has both of those covered: it lives in the water and has a huge solar collector on its back.
The shell would act as a solar power plant AND rainwater collector to culture the algae, it can then slowly eat this food, just slow enough to allow it to regenerate. Whatever biomass the algae on its back cannot provide, can then be eaten the good ol' way.
# The shell
I already mentioned the shell a lot. The way I see it, it would have to be made up of hollow interconnected cells. The outer layers would need to be at least partly transparent or translucent to allow the culturing of algae in these cells. The shell would also need to have a series of pores, some connected to the cells where algae are grown and others connected to the bones of the tortoise that would be used to draw in air.
On the inside, the shell would need to be supported by rib-like bones for both structural integrity and to be able to draw in the air needed to breathe. The inside surface of the shell would probably be very porous to allow the body to consume the food and resources stored inside.
From your other question, I believe you want to put people on top of the tortoise. The people could exploit these systems to keep clean rainwater. Algae are nutritious, so they also have a food source (just don't overexploit it)
# Other organs
There are too many organs in an animal to feasibly list in this answer. Though I believe most of them can be distributed into a number of smaller organs, even the brain can be distributed through the body.
# A few other details
Given the structure proposed and the way things would work, it will probably be best if the tortoise is mostly flat, that is, only a couple dozen meters high at most. This way you'll have a lot of shell area, which is very important here, very close to most of the body. It also eases on the load of having a lot of organs on top of each other, crushing each other.
It also makes the floating more stable and the structural load lower.
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If the tortoise actually has to walk on legs, this is not going to be possible without magic or sophisticated technology indistinguishable from magic. If the tortoise doesn't actually have to walk, and most of its weight can be supported by the water, you might be able to pull this off by having it use its legs like barge poles to move around in the water. Also, it's not going to look much like a tortoise. Its head and legs will be very tiny compared to its body, which will contain a lot of empty space to produce the required buoyancy. It will probably resemble a giant engorged tick covered with debris.
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If you handwave energy requirements, an underwater creature can be arbitrarily large since the density of organic materials are basically the same as that of water. The hard part to explain will be the part of the body sticking out of the water, in our case, the "shell". However, it could be that the shell is made of a buoyant material, like wood, or one full of air pockets, similar to pumice, allowing it to float. Pumice does eventually sink, but the shell could also be covered with a thin membrane that traps gas and some organic process could replenish it as it leaks. Decaying organic matter is a good source of gas. It doesn't smell too nice, but being pleasant to live on wasn't one of the requirements, was it?
The main issue with such a big creature is figuring out what it eats. If the shell is covered in plants it might have some sort of symbiotic relationship with them allowing it to gain energy from photosynthesis. It might also have something in it that attracts plankton or small fish into its mouth, allowing it to feed with minimal energy loss. Even so, don't expect it to be moving around very much.
Oxygen exchange will be an issue as well. This creature will not be able to raise its head above the water, so it will probably either be a water breather or breathe through openings in its porous shell. If it has gills, they may be extended into the surrounding water to make oxygen exchange easier, similar to the gills of an axolotl, but even bigger. This will make it more vulnerable to parasites, though.
There's not much reason for a creature like this to look like a tortoise, so if it's a natural creature I wouldn't expect it to. A giant jellyfish or kelp would be more likely.
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I have an idea for a scify/lost technology world, that I would like to check the plausibility of.
*What I want*
A terran world of large size. The crust of the world is thin, and hostile gas-organisms live underneath. During rare earthquakes poisonous gasses can rise, and once in a bicentennial blue moon sometimes landmasses can even shift to new global positions, blown of when huge amounts of gas erupts somewhere else.
This catastrophe-prone world is habitable only because of its size - even a shift in global position will entail a smaller shift in climate zones if the planet is large enough.
*How I thought it could be done*
A terran world of gas-giant proportion, where the tectonic plates are really thin and rests on the compressed clouds of the (jupiter-style) gas giant.
*Proposed method*
For human life, it had to be shifted into a goldilocks-zone, which meant to pass it through an asteroid-belt. The tectonic plates are essentially hollowed out egg-shell shaped asteroids and cannibalized moons which simultaneously where sunk on the gas-giant, trapping light gasses underneath. Later fused, with gasses and water harvested from the world itself.
*Question*
Is this idea completely bonkers?
What would need to be done differently to make it work?
Are there better ways of achieving my initial desire?
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What you are proposing sounds much like the Supramundane Worlds concept of [Paul Birch](http://www.orionsarm.com/fm_store/Paul%20Birch%27s%20Page.htm). A gas giant planet like Jupiter is not usable in its current form by humans, but if you could build a shell over the atmosphere you would create a "world" with many times the surface area of the Earth.
While this isn't possible with today's technology, in the far future, sheets of woven carbon nanotubes or Graphine could be used to build the "deck" over the atmosphere of Jupiter, and then an ecosystem overlaid on top of the "deck". Obviously, such a structure isn't going to be in one piece, and the seams where the various panels are attached would serve much as the edges of the continental plates on Earth. It may even be possible that the edges are deliberately unattached, to allow for flexing and thermal expansion in order to relieve stress on the overall structure.
Obviously these engineering zones would have been marked and put off limits during the initial construction and early habitation of the Supramundane world, but after thousands of years of habitation, the memories and instructions of the initial colonists are long forgotten, so wandering into the area of one of these expansion joints would have much the same effect as you are looking for.
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Your question is actually three questions, with three separate answers.
**1: Is it bonkers?**
Yes. This can't happen the way you described. A solid won't come to rest midway down a liquid (or gas) that it otherwise sinks in (though Terry Pratchett has a beautiful section describing dead ships sailing underwater in the Diskworld series and there are liquids dense enough to float on), so your 'plates' won't float unsupported. If the whole crust is one shell surrounding the core of the planet then any kind of crack, fracture or instability would shatter it like an eggshell under a stiletto.
The second issue is the method of capture for these rocks: You describe the planet passing through an asteroid belt. Firstly it would have to be one hell of a dense asteroid belt to coat a gas giant in rock. Asteroid belts aren't the common trope of dense fields of rocky shards bouncing off each other. Even planetary ice rings don't achieve the kinds of density I think you'd need for this. Not only that: but these rocks are going to be hitting your gas giant at one heck of a speed: more than enough to punch down past whatever fragile equilibrium point you established.
Even if you manage to find a neutral buoyancy rock and have it suspended by thermal updrafts or stratified liquids or similar you hit another problem: Your human beings can't possibly survive. If the gas the plates are floating on is dense enough to support rock then either the gas above is dense enough to kill the humans, the humans are dense enough to sink through whatever makes up the plates or the plates are under a lot of pressure from below (which would tear the plate apart). In any of these cases humans die horribly.
**2: What would need to be done differently to make it work?**
Strangely enough this is a concept that I fleshed out for one of my first fully featured worlds, and it's a common trope throughout steampunk fiction or any kind of 'floating island' world where magic isn't allowed. Some form of element that is a room temperature superconductor. In your case specifically it would be held up by magnetic locking in the magnetosphere of the planet's metallicised hydrogen core. If this element is common and ubiquitous enough in the crust of the planet then you can fine tune the height of the plates in the atmosphere. I'm fairly sure there is another question on WB about whether there is an idea height for this, so have a look around and see what you can find.
**3: Are there better ways of achieving my initial desire?**
Yes, if your 'large' world is only a little large (so not a gas giant) and you're willing to give up on a totally thin crust in favour of a very 'pocketed' one.
If instead of a thin crust hanging over nothing you go with a cavern riddled planet with rare but violent bouts of vulcanism you can achieve poisonous gases, creatures living in (fairly small but still hostile) subterranean gas environments and violent rearrangements of the world that can literally sink whole continents and cause new ones to be pushed up from under the ocean, forming new pumice-stone-like continents for both the human populations and the subterranean to migrate to. This isn't exactly what you asked for, but hopefully it sparks a couple of ideas (in fact it's got me thinking of a question I'd like to ask...)
Happy world building!
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I doubt such a planet would be stable.
As soon as a piece of crust would separate from the rest (imagine a quake) the buoyancy would make it sink (high pressure gas cannot sustain a lump of rock). It won't take much before the crust would be entirely gone to the core of the planet and all living beings would be faced with the challenge of learning to fly life long in a poisonous gas.
Unless your entire crust is made of aerogel...
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There are many reasons this would not work
# A crust surface would be denser than what is beneath it.
The [density of metallic hydrogen](https://en.wikipedia.org/wiki/Metallic_hydrogen#Experimental_pursuit), a large part of Jupiter's core, is about 600 kg/m$^3$. Water is 1000, rocks in the 2000-3000 range, solid steel around 8500, etc. The crust surface would want to sink through the core into the center of the planet...where most of a gas giant's rocky material probably is already.
# Its too hot
Jupiter's [metallic hydrogen](https://en.wikipedia.org/wiki/Jupiter#Internal_structure) starts at around 10,000 K. That will melt any sort of crust material sitting on it. The molten parts will then drip and fall through the less dense metallic hydrogen into the core.
# Too much convection
The roof of the former Superdome in New Orleans was kept afloat by air pressure. This is what you are asking to do with Jupiter, to build a shell where crust-like plates can be supported by Jupiter's immense pressures. Unfortunately, Juptier's clouds, storms, and bands are kept that way by massive convective forces. The magnitude of those forces (of which there are no good measurements) would certainly overwhelm any known material. Your crust would be torn apart, the broken pieces melted, and all of it pulled by gravity and its higher density into the core.
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Up until the 1930's lighter than air aircraft were the preferred method of long range air travel. This was due to the relatively low power to weight ratio's of contemporary aircraft engines, and their poor fuel economy. A lighter than air airship (blimp, Zeppelin or other LTA craft) displaces the air and is therefore not dependent on the power of the engine for lift. A relatively low powered engine (or engines) will do for most flight regimes.
However, since engine technology isn't advancing very rapidly in *this* timeline, the various world military forces have concluded that long range bombing missions will have to be done by airships. Of course, a long range airship bomber will need to go very fast in order to reach targets in an acceptable timeframe and to evade enemy fighters. Looking at the situation, the problem seems insurmountable, *or is it?*
Reaching targets quickly and evading enemy fighters will require the airship bomber to move far faster than any existing aircraft, and also fast enough to evade detection by air observers and anti aircraft cannon on the ground as well. Some advanced thinkers believe the airships need to travel at over 1236 KPH, the speed of sound in the atmosphere! While no engine or combination of engines and airscrews seems capable of performing these feats, advanced thinkers in a few nations think otherwise:
In the United States, the US Navy is aware of [Robert Hutchings Goddard](https://infogalactic.com/info/Robert_H._Goddard) and his experiments with liquid fuelled rockets. The new Chancellor of Germany has been briefed on the activities of the [VfR](http://infogalactic.com/info/Verein_f%C3%BCr_Raumschiffahrt) (Verein für Raumschiffahrt), and in the Soviet Union, rocket research is being carried out by [GRID](https://infogalactic.com/info/Group_for_the_Study_of_Reactive_Motion) (Group for the Study of Reactive Motion). Rocket research isn't as advanced in the British Empire, but there is this [Frank Whittle](https://infogalactic.com/info/Frank_Whittle) chap working on what he calls a "jet" engine.
While flying the entire profile at supersonic speed is perhaps a bit ambitious, how can our various military forces achieve at least supersonic dash speed over the target with a lighter than air long range bomber? Assume generally 1930 era technology for the airship, propulsion systems and bombs and bombsights, but some handwaves are acceptable.
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Aside from the fact that it's basically impossible even with modern-day technology to build a supersonic lighter-than-air bomber, if your military forces *did* have that sort of technology, they would be far better served by using that technology to build a conventional, heavier-than-air bomber that was far more capable, far simpler, far less vulnerable, and far more reliable, or just build a ballistic missile that could get the job done instead.
There's a reason the Germans stopped using Zeppelins for military purposes, and it wasn't because of restricted access to helium. Airships are slow and have low service ceilings, and even as early as WWI, they were incredibly vulnerable to ground fire or air interception. With 1930s-era or early WWII technology, fighters would have flown circles around them, and anti-aircraft gunners on the ground would have destroyed them handily. Plus with the development of radar in that that era, Zeppelins would have been visible from extremely far out, giving defenders plenty of warning and guaranteeing that their targets would be ready and waiting.
What *might* be feasible would be to have your airships act as "carriers" or "motherships", making the long-distance journey at much slower speeds (the [Zeppelin bombers used in WWI](https://en.wikipedia.org/wiki/Zeppelin_P_Class) had a cruising speed of ~40 mph), and then deploying long-range rockets like the [V-1](https://en.wikipedia.org/wiki/V-1_flying_bomb) or ["parasite" bombers](https://en.wikipedia.org/wiki/Parasite_aircraft) that would then attack the target at high speed. However, this could be countered by screening targets with long-range patrol craft and radar screens, allowing for interception before the Zeppelins get into launch range.
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# With speed you do not need buoyancy
The one advantage that airships offer over winged aircraft is that airships do not require **speed** to fly while airfoils do. And for a short while in history, this meant that airships could lift more than aircraft because engines were not powerful enough to propel an aircraft that could lift as much as an airship at the speed required to lift it.
But from the time there were engines that could propel aircraft that could carry 10 tons or more, airships offered no advantage over fixed wing aircraft(\*). To haul 10 tons, why spend [a crew of 40, flying at 10 000 ft and 130 kph](https://en.wikipedia.org/wiki/Hindenburg-class_airship), when you can carry the same cargo with [a crew of 11, at 30 000 ft, at a speed of 570 kph](https://en.wikipedia.org/wiki/Boeing_B-29_Superfortress)?
Static lift has its uses. But once you can attain an airspeed of 200 kph or more, [airfoils](https://en.wikipedia.org/wiki/Airfoil) will [beat aerostats](https://en.wikipedia.org/wiki/Aerostat) every time.
(\*) ...with the one exception of immense passenger comfort and luxury
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I'm no expert in aviation, but based on the first supersonic flight (The Bell X-1) try something like this (as far as I can tell you will however need some handwave to preventing the thing form either exploding or tearing apart as soon as acceleration starts):
* The ship would have a solid frame and a hard outer shell. The gas bags contained within.
* To reduce drag, the gondola should either retract into the superstructure, or be internal in the first place.
* The superstructure must not only be as aerodynamic as possible, but also capable of withstanding the g-force inflicted during acceleration. The gas bags must also be strong enough not to burst.
* Stabilizing wings and a tail (So that the ship doesn't corkscrew as soon as the jet/rocket starts).
* Rear mounted rockets/jet engines for mach-1 bursts, and retractable props/screws for standard flight.
You could make it a teensy bit more believable by having these ships take massive damage when performing a mach-1 burst, only using it in dire emergencies or to deliver their payload before going down\*.
\*In fact using smaller suicide airships of this design (manned or unmanned) would make an interesting anti-bomber defense.
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Airships fly using lighter-than-air gas, mostly hydrogen or helium. The difference in weight is large in relative terms, but small in absolute terms. They need **a lot** of gas for their weight.
A large volume means a large surface area. A large surface area means a lot of drag. Shapes and materials can mitigate this effect, but they cannot solve it.
To overcome that drag, the airship needs powerful engines. The F-104, the F-15, and the F-22 have *roughly* half as much afterburning thrust as their loaded weight. Airships would need no drag-producing wings and they would benefit from the square-cube effect, but that probably won't be enough.
*If there are supersonic airships, they are big.*
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I don't think supersonic airships are viable, but with bad engine technology flying really high up is a good way to protect yourselfes.
Airships can reach high altitudes with quite small and weak engines, if they have **a lot** (really big) of space for gas and have good presure resistance.
The relevant formula for the size is (p\*V)/T = const. As an extreme example the [Explorer-II](https://en.wikipedia.org/wiki/Explorer_II).
Having such a big size will make them quite visible though so long range armament might be a threat.
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Is it possible for humanity to completely annihilate itself? By that I mean there cannot be one survivor left and the annihilation must be caused by humanity itself with current technology (no crazy AI killing everyone) and not by natural disasters (no giant meteorite).
The following come to my mind but won't achieve 100% annihilation:
Nuclear war:
There will still be some survivors and some place on earth will have tolerable radiation levels.
Genetically engineered killer pathogen (virus/bacteria/parasite):
Because our gene pool is so diversified, some people will naturally be immune to it, some people in remote area won't catch the pathogen.
Desertification/Global warming:
Some areas near the poles will still be fertile.
Mankind is kind of tough to get rid off!
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## 8 Possible Methods
**Superbugs (Intentional)**
An act of biological warfare planned extremely precisely may be able to wipe out the global population. It's not likely, but then again, nothing is likely to completely annihilate all of humanity; *life finds a way.*
If a virus, bacteria, or prion is designed to kill with the most efficient incubation period, methods of spread, etc. and planted in multiple countries (or even better spread by drones through the air near airports and in major cities across the world) it may be able to kill the population relatively quickly. As with all of these methods, people in isolated places like Antarctic research stations and the International Space Station will not die so quickly - it will have to be from a lack of resources.
Note that this pathogen must specifically be delivered to isolated places - remote islands, cruise ships, etc. to *really* kill everyone - but that those who survive may end their own lives.
It's also worth mentioning that an engineered pathogen need not worry about "natural immunity" - there are bound to be ways to bypass this if you can make the perfect biological weapon.
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**Superbugs (Unintentional)**
Similar to the above - however, this involves unintentional human actions creating a pathogen, which, by pure luck, conquers the planet. Very unlikely, but not impossible.
We're already creating "superbugs" every year by [overusing antibiotics](http://www.npr.org/sections/health-shots/2016/09/08/492965889/watch-bacteria-invade-antibiotics-and-transform-into-superbugs). In cramped, industrial sized farms, livestock in bacterial breeding grounds are pumped full of too-strong antibiotics. The bacteria that survive proliferate, and, when their ancestors are exposed to the new rounds of stronger antibiotics, the ones that survive reproduce, and so on - until we're left with multiple recorded cases of bacteria we don't know how to kill.
All it takes is a bacteria that can be transmitted to humans, with negative effects and high transmission - and the pure luck to kill us all.
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**Nuclear Warfare**
A dispute between countries, or better yet countries with nuclear allies against countries with other nuclear allies, may cloak the planet in radiation. This would poison and kill much of the civilian population, and only a handful of people in bunkers would survive. Astronauts would starve before NASA could get them down, and Antarctic researchers would likely meet the same fate.
Those in bunkers likely wouldn't survive due to [nuclear winter](https://en.wikipedia.org/wiki/Nuclear_winter#Consequences): clouds of soot would lower global temperatures, meaning people emerging from their bunkers (provided there was enough food) would not be able to farm efficiently. Additionally, it has been suggested that this type of event would destroy the ozone layer - showering the frozen Earth with deadly radiation, complicating or ending complex life for a very, very long time.
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**Overcrowding and Resource Mismanagement**
Following some models of population growth, the Earth may run out of space and resources before we solve the problem of overpopulation itself. While this will cause mass deaths, the remaining population can still get by. Eventually, these cycles will deplete the Earth's natural resources. According to [Stephen Hawking](http://www.space.com/8924-stephen-hawking-humanity-won-survive-leaving-earth.html), we must leave Earth, or else this is what will end humanity.
The problem with leaving Earth after we consume it (think WALL-E) is that we do not have economically viable means to transport thousands, let alone millions or billions of people to another location - the majority of people will be left on Earth as the population starves.
Those not included in "the majority" may actually be doing fine, in a colony on Mars. In order for the colony to sustain itself without requiring materials from Earth, it must be able to mine for every possible mineral used in every computer or robot part, grow every type of food needed without new shipments, refine and process all materials, maintain electricity (nuclear batteries and solar panels only last so long), and find water (groundwater reserves are great but they may dry up), *among other things*. I wish these colonists luck, but it probably won't work out.
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**Grey Goo and Ecophagy**
A slightly more "out there" approach. This suggests that we will develop the field of [nanorobotics](https://en.wikipedia.org/wiki/Nanorobotics) to the point that we create swarms of self-replicating machines. These swarms could, if not controlled, grow exponentially, devouring ecosystems in their quest to reproduce. Supposedly they may be able to sterilize the planet; whether this scenario is actually realistic is up to you.
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**Evolution**
A less depressing method, this suggests that humans will evolve over time until we become a new species - compare humans to our primate ancestors - which would technically mean humans "annihilated" themselves just by reproducing.
While this is a clever approach, it may be less likely than the above scenarios. Evolution favors isolated populations - see the biodiversity of the Galapagos Islands - because traits can be passed throughout the species relatively quickly. There are over *seven billion* of us, and we can travel anywhere, to reproduce with (evolutionwise) *anyone*. Any new changes made will be watered down, *fast*.
Additionally, humans don't *need* to change, so they may not. In a world where antibiotics and surgeries sustain those who can't cope with "survival of the fittest" we may not be pressured environmentally to adapt.
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**Triggered Supervolcanism**
Another slightly out-there suggestion, although not impossible. This suggests that something like a nuclear weapon can trigger or speed up a [supervolcanic eruption](https://en.wikipedia.org/wiki/Supervolcano) slated to occur soon. Such a release, multiplied by the number of supervolcanoes in the world, *may* be comparable to a nuclear winter, which, as described above, would be more than enough to wipe out humanity.
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**Pissing off the Neighbors**
Very unlikely, but I'm including it for fun. If humans anger aliens with weapons of mass destruction - capable of sterilizing the Earth's surface - we will indirectly result in our own annihilation.
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Do you mean theoretically, or in practice?
Theoretically, the answer is surely yes. One can easily imagine hundreds of scenarios. Take a simple one: For whatever reason, half the population get knives or guns and kill the other half. Then the survivors kill each other. Etc etc until there is only one person left, who commits suicide. Or maybe the last two people simultaneously shoot each other.
In practice, I don't see any likely way for it to happen. As you state in your question, every disaster scenario you can think of, there would always be some number of people who through foresight or luck manage to survive.
In a war, surely some would survive in bomb shelters, or just be fortunate enough to be in an area not targeted by whatever weapons we're supposing. You don't even have to suppose they are in the Antarctic or something. Even in a nuclear attack, surely there would be places in, say, Wyoming or South Dakota that are not hit with missiles, and are far enough away from targets that they don't suffer serious fallout. And surely there would be many countries not involved in the war at all. If, say, the US and China fought some terrible war, it is far from inevitable that Argentina and Botswana, etc etc would get involved.
Any sort of environmental disaster would take many years to unfold. If billions of people were really dying because of pollution or global warming or global cooling or whatever, surely at some point people would decide to take action. Either to save the planet or at least to create some sort of enclave to save themselves.
It is conceivable, of course, that people could do something -- whether through war or indifference to the environment or whatever -- that literally makes the entire planet uninhabitable quickly enough that no one can react to save even a small remnant of the population. Or that people do something that sets forces in motion and no one realizes the danger until it is too late to stop it. For all our vaunted technology, I doubt that humans are really capable of destroying the planet. And even if we are, surely someone could see it coming and build a self-contained underground habitat where a small number can survive. Or send a small number of colonists to another planet. Or some such.
You'd need something that either, (a) literally destroys the planet, blows the world into a million pieces; or (b) happens so quickly that no one has time to implement a plan to save even a small number.
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Rooting humanity is next to impossible. Meteors can be diverted, also safe havens could be built underground. There will be survivors to a nuclear apocalypse. A group can hide from gaze of an homicidal AI. Global warming will not affect underground bio-domes built to survive that disaster. There is only one way to root out humanity: destroy the planet, and fast. Otherwise they will run out to other stars.
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Sometimes the simplest things are the most efficient.
For the result you have in mind (since you are not stating a time frame, only a tech level):
**Just throw a rock.**
Admittedly it would need to be a big one, but space is not only huge, mind-bogglingly huge, it also contains rocks of various sizes.
So, let's build an unmanned spacecraft, send it out to a suitably lump of mineral, and push it a bit, so it's altered path eventually makes it collide with our planet.
Provided your rock is big enough, you can make really big splash, killing everybody.
A big bonus: from the moment where anyone notices what is happening, there is nothing mankind has in it's arsenals to stop i from happening.
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I tend to agree with Cem Kalyoncu, killing off 100% of humans from this planet with our current tech would be near impossible.
Without creating a super air-bourne virus, or a deadly AI, or gaining the space-tech to throw a big enough rock at the planet, there would still be people left.
We could even adapt to environmental changes caused by global warming or a nuclear winter. Many would die, yes, but there would always be some survivors.
The only scenario I can think of, without creating new scientific discoveries, where we would all die is if we regressed technologically. Our advance of technology stopped or slowed. And never advanced. Ever.
Not even after thousands of generations. No technological advances even after millions of generations - then the sun will grow big enough to wipe us all out.
[If we do nothing, and stay on this planet forever, it will eventually take us out.](http://www.bbc.co.uk/earth/story/20150323-how-long-will-life-on-earth-last)
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A nuclear war with a sufficient amount of [Cobalts bombs](https://en.wikipedia.org/wiki/Cobalt_bomb), can cause the extinction of most life form on earth, humans included.
However the life still survive, because there some species of bacteria extremely resistant to radiation, like [Deinococcus radiodurans](https://en.wikipedia.org/wiki/Deinococcus_radiodurans).
If in future we are able to create an antimatter bomb, with a simple war we can wipe out the entire planet.
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Release a disease cocktail all at once. Release small pox, plague, measles, hepatitis, malaria, aids, flu, ebola, anthrax, tuberculosis, etc.
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Convert the world's supply of h-bombs to cobalt bombs. Detonate. There will be no long term survivors. You're not going to be able to hide out in your shelter long enough.
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Yes, and it almost happened. In the Cold War, both the US and the Soviet Union had more than enough nuclear warheads to wipe out not just humanity, but all long-term life on Earth.
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The USSR had over 35,000 warheads at the peak of the conflict
The US had over 30,000 warheads at the peak of the conflict
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[The Republic of Indian Stream](https://en.wikipedia.org/wiki/Republic_of_Indian_Stream) was a small area of land near Quebec (or New Hampshire for you Americans) that was a result of a poorly worded border claim, it resulted in a 731 square kilometer section of unowned land named the Indian Stream. Despite being just a lack of foresight in the wording of the treaty, the 300 residents of Indian Stream took it **very** seriously, declaring themselves an independent republic on July 9th, 1832.
Even assuming it keeps its borders and doubles in population every 46 years, it would be the 176th largest nation (Taking Singapore's place) with the second smallest population, only better than the Vatican State. Obviously, such a country couldn't be strong or powerful, but that is not necessary.
In the real history, The Republic of Indian Stream was annexed by New Hampshire in 1835, but does this need to happen? What is the smallest historical difference I can make to prevent this annexation?
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Bad news 1: the size of the Republic makes them insignificant in any political and diplomatical sense, and it is at the mercy of its neighbours.
Bad news 2: USA at the XIX and first half of the XX had that pesky "Manifest Destiny" doctrine by which they claimed all of the land they could grab from their native habitants or its neighbours.
Good news 1: the size of the Republic makes them insignificant economically, so if they get recognition by their neighbours there will be little interest in changing the *status quo*.
Good news 2: Since 1812 there has been no war between USA and Canada/UK, so there is little strategic interest.
One possibility is that both parties to the treaty (UK and USA) keep their interpretation of it, and make clear to the other party that if, should they infringe against their sovereignty, it will mean war. This allows the country to keep their independence even if unrecognized; with enough time it just becomes "natural" that the region is neither controlled by Canada/UK nor by the USA, and the lack of negative consequences of this situation allows the leadership of both sides to be less anxious about changing the situation.
You can add to this PR feats by inhabitants of the region (vg. Streamist soldiers joining the Union army as "foreign volunteers" during the Civil War, or an intrepid Streamist exploring the depths of Africa for the glory of the British Empire) to give them some international, if not recognition, at least publicity.
Of course, during all of this you need your fellow Streamites to be very convinced of the need to preserve their independence and that their neighbours know that they will fight for their freedom to the end, to the point that it is well understood that annexing the country will need military action.
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The annexation itself seems to have arisen from them expelling tax collectors from both New Hampshire and Quebec, they didn't want to pay double taxes. This led the sheriff of Coos County, New Hampshire to call up the militia and annex the area. He had 2 companies of infantry (150-500 men) easily more soldiers than the entire population of the Republic.
It is very unlikely they could withstand even this small military of local militia's without some extreme outside help.
The smallest difference could be a different sheriff in Coos County, one less likely to call in the militia over unpaid taxes, this might have delayed the dissolution of the republic, but eventually Canada and the US would have clarified their borders and one or the other country would formally claim the territory, at that point there is nothing the people could do about it without outside help.
Given the size and low population of the territory, It seems unlikely any outside power would take an interest in the issue. An appeal to the Canadian or US governments would only end in their being incorporated into one of those countries, although possibly as a new state or province under their own government.
A long shot would be a direct appeal to the British crown to join the empire as an independent nation.
If you look at most micro-nations surrounded by other larger countries, most exist as city states (high population density) and have outside allies supporting them militarily. The Republic of Indian Stream had neither and is unlikely to exist as an independent nation without both.
Further the declared [Monroe Doctrine](https://en.wikipedia.org/wiki/Monroe_Doctrine) of 1823 made it very unlikely that a European power would interfere without drawing action from the United States.
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Have the New Hampshire militias refuse to mobilize for the invasion. Such an act was not unheard of, as militias sometimes mutinied, disbanded, or refused to muster when they thought the fight foolish, unjust, or impractical, as in the War of 1812 with the abortive invasion of Canada and the fight in New England.
After that initial hesitancy, you can have the higher officials in the US and British governments learn of the dispute and, because they are fearful of a war over a an insignificant piece of territory (as they apparently were in real life), put the kibosh on any future aggressive action. Provided that the people of Indian Stream are content to be independent and not isolated from commerce with either the US or Canada, you can just have the status quo carry forward until its independence becomes accepted as a matter of course.
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## They Incorporated in Late 1814 Rather than 1832
What a difference 18 years makes!
In the year 1814 - towards the end of the War of 1812 - the people of the Republic of Indian Stream discovered the ambiguous wording of the Treaty of Paris while a few men debated which side of the war they should fall under. Not seeking competition with two actively engaged countries at war, a representative was sent to both Canada and the United States with a unique offer - ratify RIS as a neutral territory for use in diplomatic discussions!
And so it was.
Unfortunately for the soldiers who were wounded or lost their lives, the processes involved with ratifying the RIS as a neutral country took sufficiently long to resolve (~6+ months) that the country was never used as a convenient location for civil discussion on alternatives to continued aggression.
Following the war neither country had an appetite to attempt to capture the territory as the RIS was a symbol of joint, peaceful cooperation.
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[Cobaltduckworld](http://meta.worldbuilding.stackexchange.com/a/3845/10851)a has had somewhat of a similar biological past as earth, but not exactly. As examples, sentience has happened multiple times, and not just in primate-like species. Beasts that didn't survive our ice-age continue to roam the plains of cobaltduckworld. Mammals arose and eventually led to humans and dolphins and horses, but also elves and [brocc](https://worldbuilding.stackexchange.com/q/20335/10851). And oh, yeah, there are pterosaurs.
Once, there were velociraptors and iguanadons and many others as well. They went extinct some 10s of millions of years ago, but not the pterosaurs. Pterosaurs survive in the modern era, with dozens of species ranging in size from about equal to a duck to twice that of a condor.b
Maybe it was a meteor in a different form, or a continent-splitting geological upheaval, or a radical shift in climate. Everything that happened to the "dinosaurs" on earth happened on cobaltduckworld, *except for the pterosaurs.*
The challenge is to explain what this event was, and how its aftermath played out. Magic is allowed, but not encouraged.
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a I really need to think of a proper name.
b I know I keep saying that modern literature needs more quetzalcoatlus, but I don't want my humans to get eaten.
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There're many species today that survive the Cretaceous extinction event, like crocodile, bird, mammal, fish and so on. We can look at them, learn their strategy, and apply that for your ptero.
Mostly, it's about eat less and eat everything.
1. eat less
Things like much smaller size, being coldblood, and the ability to hibernate will help a lot.
2. eat everything
Being omnivores also help. Find out what species would survive the extinction and made it your diet. For examples, 90% of the bonyfish families survived, as well as insect; so just eat them. Moreover, because your ptero can fly, they can access distant islands that out-of-reach from other species, thus reducing competition.
and finally, just cheat like TrEs-2b said. Your ptero may not survive, but some kind of small raptor did, and they will spend the next 65 million years to evolve back to pterosaurs.
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This is tricky, but to do what you want, you're going to need to edit any pterosaur that ever existed, or just cheat.
1. The former strategy is to edit what the inside biology looks like in a pterosaur. I would suggest making ancient, before extinction pterosaurs evolve warm bloodedness inside of being cold blooded, also making them omnivores will help them survive the super winter that the meteor will cause, but there is another solution.
2. Just cheat! If you look at current bat evolution, some speculative and future biologists suggest they are evolving to have wings akin to a pterosaur and this is a real possibility, by having bats evolve much much sooner in earth history, you can possibly have mammal pterosaurs.
[](https://i.stack.imgur.com/BVA9y.png)
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It has to adapt, find new sources of food after the mass extinction event as most probably, the death of pterosaur is caused by the loss of food source. But this also might mean that they need to be smaller. That said, it is possible for them to get larger when the time got right.
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This [pterosaur website](https://pterosaurheresies.wordpress.com/2012/01/24/why-pterosaurs-are-extinct-today/) says that SMALL pterosaurs got through previous exinction events, but because there were only large pterosaurs at the end of the Cretaceous, they became extinct.
So, invent a lineage of small pterosaurs. They survived. Then over millions of years, they evolved into various sizes of descendents - small, medium, large and giant Quetzalcoatlus.
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The major problem is that by the time of the K-PGe Extinction, the pterosaurs were already in decline and had been for quite some time because of the avian dinosaurs which had outcompeted them in just about all niches aside from "Giant flying thing". And big things didn't tend to do well in the extinction. So you need a lineage of small pterosaurs that can somehow deal with competition from the birds.
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Make them small. Small pterosaurs survived 2 extinction events, but alas, since there were only big pterosaurs at the end of the Cretaceous, thus, they became extinct. Your pterosaurs would need to be small, as big as the pterosaurs in the Triassic. Than, take advice from the carnivores. The creodonts died out because they ate meat exclusively, but the carnivores were omnivorous at the time, thus allowing them to survive. Your species would need to eat everything that's smaller than them, or hunt in packs to bring down larger prey. At the right time, of course, they could become big.
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Say a sorceress secretly enchanted 1 million kids, 12 years old, and under and made them break into Area 51 from all directions what would they do?
These kids appear very normal and sane apart from the fact that they will die before abandoning their mission, like suicide bombers.
The media are tipped.
What do they do?
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Looking at a map of the area around Area 51, I will say that there aren't a million people for miles and miles around, let alone children, let alone one million children exactly the age of 12. Las Vegas Nevada is 2 hours away. The TOTAL population there is about 600 thousand. About 25% are under the age of 18. That's only 150,000, and of those, only a very small percentage will be age 12. (With an even spread of ages, that would be a bit over 8,000). The age range isn't clear. Are we talking toddlers as well? 12 is a good age because, at least then they can reach the pedals of a car.
That means that many of these children will have to travel some distance. The media wouldn't have to be tipped--people would notice that their children are gone long before they get there. We are not living in an era where parents say "I'll see you at dinner kids, go play outside!" Nope.
Let me add as well, that parents often have social circles with other parents who have kids the same age. If one kid is missing, they will start calling other parents. Even if those other parents are somewhat neglectful, they will immediately want to know THEIR kid is safe. Then, they will find their kid is missing. It would not be long before these groups notice all the kids are gone, nor would it be long before those parents inform the police. If even 1/8 of the parents of just the 12-year-olds opt to call the cops in Las Vegas (and I am thinking that's a conservative estimate) they will get 1,000 calls. And the cops will communicate with other, nearby cities. Then they'll notice a pattern and will start calling all the cities in the area. Nothing motivates like kids, so there will be a task-force so very quickly.
Plus, the kids will have to steal vehicles in order to survive the journey at all. That means that some will die in car accidents because they don't know how to drive. And they'll be stopped along the way. So long before they even get to Area 51, there will be incidents of violent children. The media will already know about this, and will already be tracking them.
While the pre-game stuff (getting there) is not in your question, it's highly relevant, because it means this will not be a surprise for anyone, not the military, and not the media.
Because of that, there will be enough time to formulate a non-lethal response, which is exactly what they will do. Law enforcement will likely be asked to help, things will be locked down, and there will be at least one child that's been captured and studied, so they know what they are dealing with. Much of it will still be mystery, but there will be more advance warning than your question indicates. Tear gas, knock out gas, non-lethal weaponry will all be brought to bear. Lethal weaponry will be a last resort, but it will be used.
Remember too that because many of these kids will be travelling from a long way away, and they do have to sleep.
Just checked the [national census](http://www.census.gov/popclock/) as well. There are 324 million people in the United States. 12 year-olds make up roughly 1.25% of our total population in the United States. There are 4 million of them in the entire country. That definitely means that you will have to draw from several days journey away. This will involve the population of more than one state. The amount of time means that it will be national news long before they all arrive at Area 51. Going to say that several days will have to pass in order for them all to arrive. The West Coast has some decent population centers, don't think you'll have to delve into the East Coast. Know you've got kids under 12 on that there, but will they be able to travel well? Kids younger than 12 are generally fairly well-supervised. Is it during the school day? On a weekend?
If we use 10% of the population (which is roughly what kids from 6-12 make up) then there are larger numbers, but there are far more problems when it comes to getting the younger kids there, and the younger they are, the more quickly that folks will notice their absence.
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Let's assume that enough of those children made it to the gate of the installation. Three distinct questions here:
*Are there standing orders to use (lethal or non-lethal) force against 12-year-old intruders?*
I guess so, because the guards of such an installation won't just let the kids through. How can they tell a 12-year-old from a scrawny 16-year-old [child soldier](https://en.wikipedia.org/wiki/Military_use_of_children)? The orders probably include a reminder to use the minimum necessary force, but they will cover a situation where crowds are trying to break through.
*Will the commanding officer order the use of lethal force?*
Difficult to tell, especially if it is known that they are "ordinary American kids" who are somehow "sleepwalking" to the site. There will have been round-the-clock coverage in the media of desperate parents pleading for their children to come home. There may be reports how police all over the country tried to restrain the sleepwalkers with physical force. (What happens if one of them is in a jail cell? Do they try and fail to bash the door open? Run their head against a wall?)
**Wild Card:** Have the police shot any of those *unarmed children* for failing to obey an order to stop? If there footage on the web? How did that play in the national media?
*Will the soldiers obey an order to fire?*
My guess it most but not all. They know they're guarding a vital national security site, they know that *something evil* is controlling the kids, they have a clear order.
So it all turns on the commanding officer.
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Well, a million children leaving their parents and setting off towards Nevada would be noticed quite quickly, before many of them reached the area. There aren't many people round there, and if about a quarter of all the twelve-year-olds in the USA ran away at the same time, it would be pretty obvious.
So most of them would be rounded up for their own safety and would not reach the site. If they fight to keep on with their mission, it's a national problem, not an Area 51 problem.
The few who got there would be exhausted from the trek through the desert, and probably couldn't get through the fences.
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This was inspired by the answer to my first question on worldbuilding, in which I was introduced to the wonders and horrors of Harlan Ellison's "I Have No Mouth, And I Must Scream", as well as my second question- which looks to the community for solutions in building a creature perfectly adapted to a certain purpose.
At the end of the story, our protagonist has become what we may ever-so affectionately call a great, soft jelly thing. Now, this was up to the imagination given our description;
>
> *I am a great soft jelly thing. Smoothly rounded, with no mouth, with pulsing white holes filled by fog where my eyes used to be. Rubbery appendages that were once my arms; bulks rounding down into legless humps of soft slippery matter. I leave a moist trail when I move. Blotches of diseased, evil gray come and go on my surface, as though light is being beamed from within. Outwardly: dumbly, I shamble about, a thing that could never have been known as human, a thing whose shape is so alien a travesty that humanity becomes more obscene for the vague resemblance.*
>
>
>
Until the game, that is- where we're given a depiction that is hardly what anyone expected.
[](https://i.stack.imgur.com/ychqD.png)
This jelly thing, in hindsight, left me extremely unsatisfied with the prospect that in all given scenarios, this creature would be incapable of putting itself in harms way, or peril.
If I dropped a slug off of the WTC, I would expect its survival to be slim to none. What I would like to discover is how to *perfect* this hideously creative concept of AMs, and make a creature that while it has all of the abilities of the given jelly thing below, it truly has no potential to ever harm itself, at all.
Now , I've approached this a couple of times, but my solutions hit roadblocks.
* *It could be underwater!*
No, it cannot be. That betrays the fact that the 'jelly thing' lives exposed, among the air and turf.
+ *Impenetrable armor?*
This defies the point of it being a 'soft' jelly thing.
So this brings me to ask, what would be the best way of going about making a creature that is not only harmless, but free of harm- whilst still staying true to the most important features of our story-given example?
**Properties of the 'great, soft jelly thing':**
1. The GSJT is a mobile creature, albeit slow. It cannot be rendered stationary.
2. It must be *soft and moist*, similarly to the GSJT. No armor.
3. It must be a land creature, unsubjected to the softness of the ocean.
4. It cannot die from age or disease(Similarly, the GSJT is not harmed by this 'evil gray' for very long. Although this could be AM's doing, for the sake of scenario, we will assume the GSJT cannot be affected by outer toxins.)
5. The GSJT is as intelligent as a human being. A suicidal human being, no less. It will likely use any methods of maiming at its disposal to end its misery.
6. The creature does not need to eat, and it potentially is blind. (Or partially blind from the fog. This could result in either accidental or intentional injury, depending on the GSJT's location)
It is also best to assume that most harm possibilities we will be discussing regard environmental harm, such as falling, or scraping ones self on a spike or rough cliff-side, or letting ones self freeze.
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A sentience developed in a thick liquid that naturally attracts itself back into a pool would do the trick.
No matter what you did to the [pool], it won't get "hurt" - just like how you can't hurt a pool of water.
The [pool] will simply mold itself around whatever you stick in it, flow around obstacles, and slip through cracks - as long as there is a way for it to access its own pieces, and you make the attraction force strong enough, it will always reassemble itself back together.
Your "jelly" simply has to have the property to be able to always self-attract its pieces, like the pool described above. Its shape could be a pool, or a sphere (if it so chooses to look that way).
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In trying to make this creature as resilient as possible, some things come to mind.
It has a healing factor, like Wolverine or Deadpool. Therefore, if it does manage to get hurt, it will more probably recover relatively fast instead of dying.
It sticks somewhat strongly to whatever surface it walks on. If it tries to jump off a cliff, it will just slide off the wall instead, like thick honey.
It is immune to lightning. It if gets hit by lightning, the electricity goes through it without causing any harm.
It stinks terribly, which keeps any animals away. And I mean any.
It is considerably less dense than water, so it floats instead of sinking.
It can flow to some extent over obstacles. It will never be pierced by pointy things it walks over. If it gets buried by, say, a collapsed building or a land slide it will naturally flow up through any openings available, no matter how small.
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## Balloons!
Without a GSJT constructed of soft and squishy handwavium you're going to have a difficult time protecting it from **all** environmental possibilities, though you might want to look at [Balloon lithobraking](https://www.youtube.com/watch?v=KyktvC7w7Js) as a way of surviving high speed and possibly sharp impacts. Have your GSJT employ crumple zones that can survive any fall at terminal velocity.
On the topic of sharp objects again, the outer skin would also have to be strong enough to resist the maximum force the creature can exert against a pike, like puncture-proof tires on military vehicles.
This wouldn't be possible with human flesh, but AM can reshape the world as it sees fit so I don't think this is an issue.
Balloons such as these would also make your GSJT very buoyant and therefore incapable of drowning, or swimming to incredible depths to crush itself.
I'm assuming that AM keeps this creature supplied with food in some way, as life processes use energy and a simple solution would be not to eat. Therefore the creature could be engineered in such a way to produce enough heat to survive any cold climate available. Balloons would also provide a fair bit of insulation.
The last major method of killing itself I can think of would be extreme heat, in the form of fire or lava or something. To an extent, the balloon insulation would help here but sitting in a lava flow is going to pretty much destroy any material I can think of, certainly any organics. I suppose the balloons could pop with such force that the GSJT is propelled away from the heat source, but that's all I can come up with.
The easiest solution would be to put the jelly thing in a small pit that it can't climb out of, but I don't feel that's in the spirit of the question.
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Consider every likely form of death:
* puncturing/cutting/squishing/pressure/etc.
* suffocation/starvation/dehydration
* lightning/electricity
* extreme temperatures
* animals
Each of these can be countered by solutions fairly easy to identify--by a computer, at least.
* For puncturing and cutting, an obvious solution is a malleable, wet-clay-or-liquid-like body that self-attracts and reforms itself as it gets cut open. As for pressure, crushing, squishing, etc., it could be made of some sort of non-Newtonian liquid, so as if it were smashed at high speeds it would simply resist the impact until it could turn to liquid and squish through any gaps or cracks to escape.
* For suffocation, it might just not need to breathe, and for starvation or dehydration, it could survive for massive amounts of time without food or water, as both have been proven to be possible by the lungfish (max four years without food) and kangaroo rat (max five years without water), respectively.
* For lightning or electricity, it could be either non-conductive or hyperconductive; either the electricity can't even touch it at all, or the lightning just passes right through without harm.
* For extreme cold, it could have a unique internal structure that produces much more body heat than any living being in response to cold temperatures and could reflexively shrink into itself, meaning the cold is simply resisted by its own body heat. Extreme heat is a harder problem--however, it is a (potentially) solvable one. Perhaps the great soft jelly thing is silica-based, rather than carbon-based, meaning it's much more resistant to heat?
* Finally, animals. It could be foul-smelling and foul-tasting, or maybe
composed of incredibly caustic chemicals, so as to disintegrate any
animal that comes too close. Perhaps it has no special defense for
animals, as all they can do already has precautions taken against
it--it cannot be torn, cut, punctured, squished, etc..
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# Think about the Environment
It's likely quite impossible to make a soft jelly that's wholly immune to every danger in the Earth. However, there are more environments than Earth
Let's put this jelly on a great flattened planet, a perfect ellipsoid with no features. There's no sharp points to slash or puncture, no cliffs to fall from, no volcanoes to burn them, and in general there is absolutely nothing to hurt them in any way
This won't handle things like ageing or starvation. The former is easy to handle with some sort of biological immortality, as seen in many animals
Starvation is still an issue for the blob. One solution might be photosynthesis. The planet could be placed about an incredibly bright star. This star would provide plenty of energy with which to photosynthesize. This would force the blob to have an inexhaustible source of energy, never able to starve out
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Honestly I think the whole jelly thing is unnecessary, say for instance we have two AIs within the same robotic body, one AI exists solely to undermine the thoughts and intent of the other. This is the only way I can imagine Asimov's three laws could work, one of which being that the robot cannot harm itself, the intent to inflict self harm is recognised and blocked before action can be taken.
Try pushing something sharp through your hand, if you do it slowly you'll find its damn near impossible to do, if feels like your hand is incredibly tough but in actual fact you're fighting yourself for control of your muscles, we've evolved to instinctively cease any action that's causing self harm, or more specifically pain.
In the two AIs example it's not even possible for one AI to resist the other because the harm mitigation AI keeps wiping the other's cache (short term memory), for example you go get a knife with intent to stab yourself. Suddenly you're standing in the kitchen and you've completely lost your train of thought, so you make a sandwich, hallway through making a sandwich you consider suicide again, cache wipe, you don't know why you're making a sandwich but it's almost finished so you might as well continue.
This might already be happening and you would have no idea.
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In my world magic is inter-dimensional energy that came into the world after a group of scientists opened a portal. After being exposed to it some humans gain the ability to warp reality - to an extent. I also want magic (inter-dimensional energy) to cancel out any technology. But I want to give a reasonable explanation as to why this is: something more complicated than "it is magic and that is what it does".
So what is a plausible reason magic would cancel out technology?
By *technology* I mean any technology above high medieval level machines.
By *canceled out* I mean that magic either makes machines just not work at all or break down.
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The simplest way to have magic conflict with technology is to have magic subtly alter the laws of physics, perhaps in somewhat unpredictable ways.
For example, what if the presence of magic can affect how much friction there is between two objects? An increase in friction could make the grease used ineffective and cause machines to literally grind to a halt. A decrease could affect timings and throw them off, or break a part intended to pull something else along.
For electronics, it gets even easier - it wouldn't take very many transistors behaving unexpectedly before chips could get shorted out and damaged. I don't believe we have any semiconductors in our bodies, so if that's what's breaking transistors it wouldn't affect people.
If you want, you can say that people are immune to this effect. Otherwise you'll have to consider how people are affected by the presence of magic (is magic a carcinogen?).
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Magic takes energy from its surroundings in order to work.
Think of it. If you use magic to levitate a rock from the ground to the top of a table, you just put some potential energy in that rock. The energy was provided by magical means, so the magic needs to take that many joules/calories from somewhere else.
In the absence of viable energy sources for machines, that energy may be the very calories stored in the body of the mage. But this would disable or kill a mage who tried to do something big on her own. Magic may draw from the same energy sources that machines use so that the mage can accomplish greater feats. For example, if you have gasoline or coal nearby, magic may take energy from the chemical bondings in those.
Explanation: when you burn wood, coal, gas etc. for fuel, you are extracting the energy in their chemical bondings. If magic has already drained that energy, then those sources of fuel become useless for engines, for example.
As a side effect, magic may either be literally burning those to fuel itself, or it may extract that energy through means other than combustion (after all, magic is a magical thing), chemically turning coal, wood, gas etc. into other substances.
If there are electrical currents running in metal, magic may take energy from there. This starves electrical machines off of energy.
And so on...
The cool thing about this method to explain how magic interferes with technology is that it does not cause magic to simply cancel out tech... It makes both **compete** for energy. So it takes a lot of magic to stop a huge machine, for example, or a large concentration of tech to starve off a really powerful spell.
This also allows you to do some back-of-napkin calculations as to what you could achieve given some source of energy. For example, with access to a 220V socket, you could heat food just like a microwave oven would (but without the need for that oven), or you could set small things on fire. But if you sap the tank of a car that is full, you can move a ton of stuff for a few hundred miles. Or you can fly yourself for ten times as much distance. Or you can cause a projectile to fly at hypersonic speeds! Be creative ;)
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Just have your magical energy increase the electrical resistance of any silicon it passes through. That way it won't mess with any living systems, but it will make all of our computer chips heat up as the energy fails to pass along the expected paths. Shortly after any spell is cast, all the active chips within a certain radius overheat and let out their magical white smoke.
As for magic messing up other, non-computerized modern technology...? These days, there are no modern technologies that don't use computer chips in one way or another.
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new technology cancels out older technology most of the time because the new technology does a better job than the old technology. For an example, More people use Windows 10 over windows 98 because it does a better job in the purpose of its creation. I see this as the same case with Magic. In order for Magic (the new technology) to cancel out Technology as we see it as today (the old technology) it would had to do a better job than the the old technology.
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Yesterday I was talking with some of my friends about ideal/utopian worlds and came across a potential infinite loop problem. My ideal world was that of a transhumanist vision. Humans still look and even feel the same, but their insides are mechanical and computerized.
**Possibly Non Necessary Information**
This ascended humanity is able to live and colonize most worlds without too much concern as they are largely independent of their environment. They also do not need to terraform planets, as they can just alter their sensory inputs to make the planet look however they want to. They can live out their lives for as long as they desire, free from work as lesser robots and AI would perform all the manual labor necessary for them. Even if their new bodies decay, they can be brought back into a new one from a backup that is constantly being copied and stored on servers constructed wherever they go. They are still allowed to permanently kill themselves if they wish as well as work to their heart's content.
**Necessary Information**
Ascended humans have the option of leaving the real world entirely and can retreat into their own mind or on servers and live out life in a virtual reality. This last part, however, is where the potential problem occurs.
If for instance an ascended delved into their own mind, but decided for the sake of immersion to block out or even delete parts of their memory, they could end up going into an infinite loop. If they had immersed themselves into a world where a transhumanist utopia was also getting ready to be developed, they could end up doing the same thing over and over again infinitely, just with slight variations. Each iteration would lead to the creation of a new personality for the original person as each one would have grown up in a different environment and had different experiences.
I imagine that this would quickly begin to take a toll on the servers as even one person would consume a lot of data and computer space. So if one person or, worse, thousands or hundreds of thousands started to essentially reproduce asexually we would see the computers and servers become overloaded and run out of memory. I also doubt that the robotic servants would be able to keep up in creating the required space and computers necessary for these new personalities or people. I don't really know exactly, but if it caused too much overload it might even cause the servers to crash and result in the extinction of the ascended.
Even if the computer space was not a problem though, there's also the potential problem that instead of the personalities being separated and treated as separate individuals, they become one confused mess and drive the person insane. Thus leading to a group of unpredictable, psychotic, spacefaring androids.
**Question**
Regardless if you think a transhumanist utopia is possible or not, how do you avoid/prevent/fix this infinite loop in this transhumanist scenario?
Note: I would prefer it if free will was kept intact as much as possible.
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I think you need to consider how your technical garbage collection would work. At what point would a memory or personality go "out of scope" and no longer be needed, and therefore cleaned up by a garbage collection process, freeing that memory for other use. If the user is editing their memories and personalities, at some point a lot of data leaves scope and gets cleaned up. Does it really matter what Personality #12 did on its tenth birthday when you're onto personality #4125?
The better, and more sinister, answer is if you remove all references to personality #12, would the person even miss it? Would they be able to know that they had personality #12 at all? You could have a situation where you keep the "base" personality safe and sound, and just update some references, so that when "base" personality went into the recursive loop (and created personality #2) you edit that memory so that instead of waking up as personality #2, the person recalls waking up as personality #x, where x is the earliest recursion you are keeping for memory purposes. Since you can estimate the amount of storage a typical lifespan would require, you can allocate and keep y number of personalities, deleting and updating references to old ones, keeping them in a personality linked list of sorts.
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The problem is that nested virtual universes will consume undue public resources. The simple technical, if uninteresting, solution is to **deprioritize individuals who consume too many resources**.
Give each person running the reality simulator using a shared computer their own account. The device running the simulation will have a system to detect when any one user is consuming an unacceptable amount of computational power, as determined by the material constraints of your world. The device would then simulate both the reality and the user's conscious at a reduced rate, thus making the expensive world progress more slowly than the real world, but not seem out of sync for a user still in the world.
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From the perspective of the servers running the virtual reality, there would not be an infinite loop. One person could descend into any level of simulation, but only the "current" one would need to be simulated. The rest could be suspended or abandoned and regenerated by the system when the person exits a layer of simulation.
Likewise, there would not be infinite (active) personalities, just one very fragmented personality, depending on what the person decides to take with him into the next layer and then take out again.
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Your question could be shorten to: How do I fit infinite to finite?
Answer is: No way, no way.
[Exponential growth](https://en.wikipedia.org/wiki/Exponential_growth), which you have discovered for your self in that situation, at some practical point indistinguishable form infinity.
Is that problem new, or unique for your world only?
No, it's not. I'm pleased to inform you, we are (as we, I refer to any species currently available to find living, on Earth) exponential growth capable creatures. We live that way for million of years and most free will isn't harm in that time.
As free will isn't ability to do anything anywhere, I suggest you solve that simply as is done on any hosting services, limit space for copies for one individual - Sorry man, you run out of space for new copies, free the space or place efforts to extend our civilization capability's and get some space for free.
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# Return Conditions
If a transhuman gets bored and wonders, "would I do it all over again?" They can block off the memory that they are transhuman, and the memory that they have blocked off memories, and imagine a world where they are about to become transhuman, or join a server running that simulation. In either case it's possible the memories may fill the available storage, either after 1000 years or if everyone keeps asking "would I do it all over again?" and blocks off more memory. By including some standard return conditions like 'wake up whenever the server memory is at 90% or wake up if my memories are more than what can fit in my own head' you can ensure this doesn't happen. If you let them block out chunks of memory without some return condition, they may as well be deleting it. If you want to make sure they don't spend the rest of eternity asleep they can wake up whenever x time passes, or whatever.
## Simulation Depth
Alternately you could have some notification between simulations, "By the way Ted, you're already in a simulation, you can't add another level. Would you like to wake up now or keep going?" Which would only be revealed upon trying to pass into a deeper level of simulation.
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Considering that it is a virtual world, even if they keep on creating new personalities - it would be in **their mind only**. According to them (the human), they have 5 different personalities according to the type of situation, but for a AI simulating that world, there is only **one person to consider**. Some extra data will be required to show that there are more personalities, but it won't overload the servers or anything.
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If I understood you correctly, you assume that after being "digitized" a person might go the same path, to the same end - being "digitizing" again in virtual reality.
However, there must be a reason behind that decision to be "digitized". For instance, you want to defy laws of physics, use backups, control space and time, etc. That's why you go to the virtual reality.
When that purpose is achieved, though, there're no point of being "digitizing" again. Your once "digitized" transhuman must find new goals, another reasons to exist.
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Same way that we have dealt with all resource-related problems in the pre-transhuman world: make limited resources cost something.
In this digital world, we'd be dealing with data space instead of physical land and electricity instead of food, but the principle is the same. People who created new servers in the physical world (by controlling robots that acquired resources and then built the servers) could sell or rent that space to other people. We do the same thing today - server space isn't free! People could make money by producing anything that is a limited resource in the digital world - art, new ideas, more efficient programs, physical structures for producing energy, electricity to keep the servers running - and selling it to people who want it.
Creating data "clones" is basically the same thing as making children - make sure you have enough resources (server space) available to support them before producing them. The fact that they can be produced almost instantly doesn't really change anything - if you make a million clones when you only own enough data space to allocate to five and your private server crashes, that's your own fault.
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Yesterday I was thinking about LSD, and how drugging an enemy soldier with it would probably really screw up their plans of staying safe and being alive. The problem I'm still having, though, is the delivery method.
So I thought back to WWI, and chemical warfare. I imagined an artillery strike of LSD gas, which seeps through the trenches, affecting any soldier with exposed skin.
The main question I have about this, though, is if LSD could actually be converted into gaseous form, and if this gas would have the desired effect (that is, of being heavy enough to linger and potent enough to cause effects when in contact with human skin). Is this scenario possible/plausible?
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**No, not as a gas!**
But you might use it as an [aerosol](https://en.wikipedia.org/wiki/Aerosol), which will behave like fog.
However, I'd gauge this as impractical, as the fog will not last longer than a few seconds, maybe a minute, and it will not have a large area of effect. Unlike natural fog, it doesn't renew itself unless supplied with substantial quantities.
It should be potent enough though, as it will be in contact with eyes and the respiratory system.
I think for an actual delivery method, artillery or even aircraft (WWI era rigid airships) of any kind is probably out of question, as the volume of fire necessary to produce a lasting fog is too large to be feasible.
Using that many shells would have a much larger effect if you'd just shot normal rounds to create terror, which would probably be more suited to *really screw up their plans of staying safe and being alive* than the drug could ever do.
I don't know about well-trained soldiers, but on average, the soldiers in WW1 were not really prepared for the war at all - a couple of high-altitude airships dropping conventional bombs is really terrifying and is known to have induced much terror in the civilian population of cities, as did the [Paris Gun](https://en.wikipedia.org/wiki/Paris_Gun), both during WW1 by Germany.
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Actually, history is way ahead of you. For more than 20 years [Agent BZ](http://www.mobrien.com/twr/bz.htm), a potent hallucinogen, was part of the US Army's chemical weapon stockpile.
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Leaving aside "could you" then there is a white elephant in the room, why would you?
What does it offer over any number of other agents we have available to our regrettably over-full book of ways to do horrible things to each other?
If you want to cause fear or eliminate enemies then nerve agents will kill everyone.
If you want to incapacitate people then again we have agents that will knock everyone unconscious very fast.
So what would this ever be used for? Without a use-case there doesn't really seem to be any way to design a delivery mechanism.
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**Probably not** though you would need an organic chemist to tell you for sure.
The molar mass of lysergic acid is 268.32 g/mol. For comparison, oxygen is about 16 times lighter at 15.9994 u ± 0.0004 u. The molar mass of normal air is 28.97 g/mol or about 1/10th as heavy as lysergic acid. Based on nothing but simple buoyancy, lysergic acid will just fall out of the air. If the flakes are made small enough, they may stay airborne for long periods but this isn't the same kind of weaponized gas that chlorine offers.
Note, I'm not an organic chemist.
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Well like Phosgene and chlorine, Atomized LSD would fall into chemical warfare. You are putting a chemical into the air as a means of attacking other troops. Of course like any airborne weapon, you have to take care not to 'poison' your own troops.
Reading up on it a little bit [here](https://www.shroomery.org/forums/showflat.php/Number/4105759#4105759) heat, light and moisture all help breakdown LSD. So it would be a less effective attack in the desert during the day or in a jungle.
Since you would need to atomize it but still deliver it over a wide area, you can't use normal explosives since they would ruin your payload. It would also tend to fall and settle on the ground.
So the most effective way to use it would be to spread it like a crop duster over a camp in the evening/night/early morning with drones, about 30-60 minutes before attacking. Even sending a few mortars in to get things lively might be enough to set off bad chain reactions.
But it would take a specific avenue of attack designed just for such a thing. Meaning you'd likely get caught before you even get to deploy such a weapon and charged with war crimes.
[Answer]
As WhatRoughBeast mentioned, BZ is the closest thing to this in real life, though the CIA's Project MKUltra dealt heavily with LSD. Reading a bit about it via declassified documents could help you understand the "why", and maybe give you some foothold on potential "how" options. I think the aerosol would be the most likely route, but that might fit the bill based on your definition of gas. It's not a true gas, but aerosols often move in similar ways. From a layman's perspective, they are close enough for storytelling.
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**I was wondering if a full aquatic bird could exist** and not be on, or return to land at any developmental stage, basically, to be completely independent of land. I already know that there are some aquatic animals that can rest one side of their brain at a time, making sleep not an issue, but I can not figure out the rest:
* Figuring out a way to explain how a bird could evolve to be completely independent from land. The best story I can come up with is that the birds evolve into the early stages of a terrestrial bird, but then that area became flooded. However, I doubt such a scenario is realistic, and it would then be easier for the to evolve into a crane or stork-like creature.
* I am not sure what would change in their lungs that would accommodate them being submerged for such long amounts of time. More specifically, *what would have to happen to keep their lungs from collapsing at great depths?*
* Also, I'm worried about the first stages of life. Perhaps carrying its eggs in its mouth like a grouper?
* Finally, I'd prefer the bird to have some sort of mechanisms that might allow them to communicate under water , like dolphin whistles. But I cannot create a viable explanation for their nostrils moving all the away atop their heads
Any help would be greatly appreciated. ***Thank you***
[Answer]
The entirety of this problem is related to egg laying and early development of chicks, so a few things need to happen:
1. Penguins (or similar, but penguins make the most sense) need to be born with adult feathers and/or blubber layers so that the chicks can survive in the water. Even tropical ocean temperatures are dangerous to warm blooded animals who are exposed and unprotected for long periods of time. As an alternative, the penguins' core body temperature could drop by 20°C or so and the bird could be restricted to the tropics, but that seems a bit much. The whale route is a possibility here as well, with both babies and adults losing their feathers entirely, but penguins rely heavily on their feathers creating an insulating layer between the water and their skin.
2. The bird must evolve live birth. Shelled eggs have undergone massive amounts of evolution to function on dry land; getting a shelled egg to work underwater again would not be trivial. All sea dwelling members of formerly land-based vertebrates either give birth to live young (cetaceans, manatees, and some sea snakes) or are forced to return to land to lay eggs/have babies unsuited for ocean life (sea turtles, crocodilians, the rest of the sea snakes, flighted sea birds, penguins, and pinnipeds.) It's a lot easier to have the egg hatch out internally (or more realistically, fail to form/lay normally and continue developing without a shell internally.)
3. For deeper diving penguins (not at all a necessity for permanent life in the water, just ask the boto) you would need greater lung capacity and perhaps larger overall size, though king penguins can already get down to 300m or so, which is comparable to dolphins. The animal's blood would also have to be vastly enriched in its oxygen carrying capacity. True deep divers like sperm whales have adaptations to prevent the bends as well as lungs that absolutely *do* collapse under pressure. Trying to design a biological pressure vessel that wouldn't collapse is probably a bad plan.
4. Underwater communication - Penguins may already do this. Early tests of little penguins at the [Perth Zoo](http://perthzoo.wa.gov.au/singing-penguins-4890/) were not positive, but the zoo is not a natural environment. Further, it is not at all unreasonable for penguins to evolve underwater communication. They're extremely vocal above water. Dolphin/whale blowholes are for breathing, not for vocalization. They vocalize using "lips" that are located internally, near their blowholes, but they don't blow out air when they vocalize, so you could put the nostrils/air inlet wherever you like. As far as the nostrils moving up the head for breathing purposes, that's not that big a stretch, though behind-the-head whale nostrils are pretty impressive.
5. Regarding prey: There is something to eat at most any reasonable depth you might want your bird to inhabit. It would require a change of diet, but an unexploited food source is an enormous evolutionary driver.
[Answer]
**Start with a highly water-adapted bird**
Namely, a penguin. These are birds that can spend long periods of time in the ocean without really needing to return to land except to breed and molt. Of course, a large portion of the reason that penguins return to land to do these things is that the land is safer for chicks where most penguins live. To get around that...
**Throw in some dangerous land predators, and get rid of most of the water ones.**
For penguins living in an area like the Antarctic, all of their worries live in the sea. Orcas, sharks, and leopard seals will happily snack on a wayward young penguin. Meanwhile, there are no terrestrial predators for many adult penguins, with only a few birds like petrels and skuas that might prey on their young.
Because of this, penguins don't have a strong motivation for going fully aquatic. However, if they lived in an environment that underwent catastrophic warming, killing of many of the large predators in the ocean and opening the land up to creatures like cats and wolves, penguins who spend most of their lives in the ocean would be at an advantage.
If some of the penguins build floating aquatic nests, this could further protect their young from land predators. There are already some birds that do this, like grebes, who build nests on top of floating aquatic vegetation. Penguins could evolve to build similar nests made up of buoyant kelp species. Unlike mammals, penguins don't know exactly when their eggs will hatch, so it's unlikely that they would evolve to lay eggs under water, since it would be difficult to bring chicks to the surface to breathe, even if they were fully aquatic.
**Add a few million years of evolution**
Without a strong need to return to land, sea-nesting penguins would slowly lose their adaptations for doing so. Feet and legs would lose their ability to bear the penguin's weight, and penguins would slowly lose and replace their feathers like most other birds instead of undergoing a single molt.
[Answer]
You already have the perfect example, and you mentioned it in your post. Dolphins and whales are mammals that did exactly that.
We already have a lot of sea-adapted birds, including flightless ones like penguins. All they need to do is continue that adaptation a little further so that they lay their eggs underwater and the other adaptations you suggest such as moving nostrils higher would be a natural evolutionary development with a more aquatic lifestyle. Moving the nostrils isn't needed to produce whistles underwater anyway.
The diving birds already prevent their lungs from collapsing so no further development is needed there.
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This is a simple question.
What would a civilization on a flat world call the directions on a compass?
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I'm going to avoid Sir Terry's nomenclature, because it is so tied into the Discworld series I think it'd stand out like a sore thumb if anyone else used it:
**Axle** - towards the centre. Also could actually be the centre; the flat world equivalent of the Arctic - leading logically to:
**Antaxle** - the edge, and towards the edge.
**Spinwards** - obviously with the spin.
**Backwards** - against the spin.
Not really happy with "backwards" though. You could follow the Axle / Antaxle scheme and have **Antispinwards**, but I like that even less.
I was also thinking you could also use nautical terms if your world is ocean-heavy enough for sailing terms to have plausibly entered common usage:
**Runwards** - in the direction of spin; running is sailing with the wind, so implies it is the "easy" direction - the one that goes with the flow, as it were.
**Beatwise / tackwise / tackwards** - against the spin, again using the sailing terms for sailing into the wind - going *against* the flow.
I quite like "tackwards" as it implies "backwards" while sounding quite fantasy-esque.
Just realised there are two very obvious possible terms for the radial directions:
**Out** and **In**
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I used [this Wikipedia page](https://en.wikipedia.org/wiki/Glossary_of_nautical_terms#B) to ensure I remembered my terms correctly; it's a treasure trove of nautical words!
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If compasses work then the Bridge directions are fine. We did not have to discover the north pole to have a north. If the sun rises and sets in the same general places every day then east and west are knowable and the same as ours.
But remember the earth is not disc shaped but flat and square so it has four actual corners like the bible clearly states. [](https://i.stack.imgur.com/wpkK7.jpg)
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You've already answered your own question in the comments but I'll elaborate because I'm not sure you've understood them properly.
*Assuming your planet is a spinning disk* (elephants and turtle not required, what does the turtle stand on anyway\*)
**Rimward**
Towards the nearest point on the edge
**Hubward**
Towards the centre of the disk, the hub of the spin.
**Turnwise**
In the direction of the spin. You could replace this with clockwise.
**[Widdershins](https://en.wikipedia.org/wiki/Widdershins)**
Against the direction of the spin.
This is an old English word meaning anticlockwise and implies the "wrong direction".
**The Compass**
"[On the Disc, if you enchant a needle it will point to the hub, where the magical field is strongest](https://books.google.co.uk/books?id=XQ8MctA_1xQC&lpg=PA12&ots=2cYapnLcTI&dq=Enchant%20a%20needle%20and%20it%20points%20towards%20the%20Hub&pg=PA12#v=onepage&q&f=false)", perpendicular to the needle is the tangent to the Turnwise/Widdershins circle.
**The Zero Meridian**
This is key to navigation, the arbitrary point from which all others are measured. The zero meridian, as per the Greenwich Meridian lies on the line from the hub to the rim through the dominant sea trading city. Everything else is calculated relative to that position. Absolute Grid references can be given as degrees round the circle from that point (Turnwise or Widdershins) and miles from the hub.
It should be noted that navigation on open water is going to be really hard. If you're actually concerned about accuracy in such things you'll have to build a system such that it can be realistically done. Or just ignore it completely, this is probably the better bet.
\*It's turtles all the way down
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Island nations like Hawai'i use it all the time: ocean-side (makai) and volcano-side (mauka, toward the center of the island).
So your flat world would have one important direction towards the center.
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Given fact in many languages names of directions are referring to position of sun on sky, and they are originated in times when people believed earth is flat. There is big possibility, directions will be same as ours.
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When I asked my previous question about [love on multi generation ship](https://worldbuilding.stackexchange.com/questions/33662/society-rules-for-marriages-and-love-on-multigeneration-ship),
I left blank the *where* are the people going. Simply because I do not know.
Now I am in search of software which would ease some calculations.
Example: Say the ship is travelling to a system which is 35 light years away. The basic math tells me, that if I want to be here in 600 years, I have to travel 0.06c on average for the whole time (hopefully I did not mess even the basics :) )
But the thing is, such ship will probably spend some time accelerating and then braking.
Being lazy person, I am in search of software which would allow me to enter these variables and calculate time to travel:
* How far (in lightyears) am I travelling
* What is the fastest speed I want to achieve during travel (fraction of light speed)
* How heavy the ship is
* How long do I want to accelerate and brake
Is there such software I could use?
P.S.: As of the engines and/or rockets pushing the ship to movement, I feel like hand-waving this and make them from unobtainium.
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Why there is one. I use this one all the time:
[Space Travel Calculator](https://spacetravel.simhub.online/) and the source code is at <https://github.com/nathangeffen/space-travel>
Happy travels!
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You want to accelerate for half the distance, or half the amount of fuel, and then you simply turn the ship around and decelerate for the same amount of time.
Yes, really... in space where you have no friction to bother you, and where you have engines delivering a set amount of thrust — i.e. applying a force on your vehicle — it is **that** simple.
Now assuming that your story is set to have this trip to take 600 years and the distance is indeed 35ly, then you have two options:
1. the engines burn through the fuel quickly, get you up to speed and then you spend most of the journey coasting. Then the coasting speed is 0.06c... you can essentially ignore the acceleration/deceleration phase and the speed is slow enough to be able to ignore relativistic effects. This option is likely if you are using reaction engines where chemical fuels or perhaps something like the proposed Orion spacecraft (i.e. using nuclear explosions) propel you. Reaction engines are very powerful, they get you up to speed quickly, but they use up **lots** of fuels and are very bulky.
2. You have enough fuel to keep the engines burning the whole trip. Then you will have your ship accelerate up to 0.12c at the midpoint, and then you will turn the ship around and start slowing down again, otherwise you'll just zoom past your target. This is likely if you are using ion engines and something like a Polywell — or any other fusion design — reactor to provide them with energy. Ion engines are extremely fuel efficient, and they can use electricity to power them, but they do not deliver much thrust.
In either case you do not need any software to calculate this, my numbers are close enough. :)
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I'm unaware of anything specifically for this - but if you're proficient with excel, openoffice, or Libreoffice, you can create a nice little calculator for your own uses. It has the advantage of being able to be customized easily.
<http://www.wolframalpha.com/> can work pretty well for quick questions, but if you're getting anywhere near the speed of light then special relativity kicks in and things get a lot trickier.
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We can rebuild him. We have the budget... but do we have the technology?
In the process of reviewing the proposed enhancements for the Six Billion Dollar Man, such as [improved oxygen use](https://worldbuilding.stackexchange.com/a/28169/3202), the following was discovered:
[](https://i.stack.imgur.com/BJCGX.jpg)
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> **Enhancement**: Bionic Eyes
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> **Purpose**: Implanted device significantly improves the [visual acuity](https://en.wikipedia.org/wiki/Visual_acuity) of the subject and provide limited night vision.
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> **Mechanism**: Existing eyeball (if any) is replaced with apparently identical version consisting of optics and photoelectric array. The replacement eye may also contain an infrared light source to provide active night vision illumination. Power is supplied by BodyGrid® while image processing and neural integration is output to the existing BCI, ThinkCap®.
>
> **Resulting visual acuity**: Better than [Snellen](https://en.wikipedia.org/wiki/Snellen_chart) 20/1 (6/0.3). Upper limit unknown.
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> **Feasibility**: Unknown.
>
>
>
Please help fill in the blanks.
The power, image processing, and neural integration are taken care of, but what about the rest?
**Can an artificial eyeball replacement be built which will increase the visual acuity of a person up to and beyond the value given and provide night vision?** Assume projected 2050's era technology.
**What is the best resolving power that can be achieved with this visual prosthetic?** Simply through optics and feasible photoelectric array density, whether the brain can interpret the information [has already been discussed](https://worldbuilding.stackexchange.com/q/21693/3202).
The eyeball only needs to contain the optics, image capture electronics (if electronics are the way to go), and an IR light source if active night vision is required. It should externally appear to be a normal eyeball (from a little over a meter away, [uncanny valley](https://en.wikipedia.org/wiki/Uncanny_valley) is ok) and be able to be connected to the extraocular muscles for normal movement.
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The human eye is a [diffraction-limited](https://en.wikipedia.org/wiki/Diffraction-limited_system) optical system, and while it has a typical resolution of 60 arcseconds, should have a theoretical resolution of as low as 20 arcseconds based on its aperture - the human eye's aperture being the diameter of the pupil.
It is possible to create a sensor array that can sample an image at the limit of this resolution. Improving the resolution of the sensor beyond the limits of diffraction will not provide any increased clarity - it will merely take additional samples of a blur.
As an example, imagine that we have a point source of light. The optics focusses this light on a sensor. The limits of diffraction means that for a given set of optics, the focussed image of the point source has a minimum size that may be larger than the size of the light source. By adding pixels to a sensor, we merely make the edges of this blurred point smoother.
It is unnecessary to have a sensor array with a resolution significantly higher than the limits of diffraction of the focussing elements.
So, given the theoretical limits of the optics that we can fit into a *natural-looking* human eyeball, the best visual acuity that we can expect in the visible light spectrum from such an instrument is 20/6.67 or 6/2.
If we are prepared to accept an unnatural appearance, and instead of a pupil diameter of around 4mm, we had a pupil diameter of 20mm, this would improve the resolving power to around 9 arcseconds, giving a visual acuity of 20/3 or 6/0.9. With an [orbital size of around 24mm](https://en.wikipedia.org/wiki/Human_eye), it cannot be expected that a maximum aperture much greater than 20mm could be achieved.
The possibility exists that an artificial eyeball might deliberately limit its aperture in order to present a socially-acceptable appearance, while having the capability to open its aperture beyond that normally expected for a human eye in order to increase resolution.
As to the question of night vision, it should be possible to construct the lens of this artificial eye in such a way as to allow transmission of infrared light, and from there, the optical sensor could be designed to be able to capture infrared data.
However, the limits of diffraction are dependent on the wavelength of the light in question, and the resolution of near-infrared light might be 120 arcseconds, giving 20/40 or 6/12 vision in the near infrared spectrum. Opening the aperture to 10mm might give a resolution of 80 arcseconds, or 20/26.67 or 6/8 vision. Opening the 20mm might give a resolution of 60 arcseconds, which would give 20/20 or 6/6 vision in the near infrared.
There are other considerations to night vision too. In low-light conditions, an electronic sensor is capable of time-weighted averaging of incoming photons. Since the [flicker fusion frequency](https://en.wikipedia.org/wiki/Flicker_fusion_threshold) of the human eye is 15 to 60 Hz, and the sensor would be receiving photons continuously, by increasing the sampling rate and then using averaging techniques, a visible-light image with the requisite frequency can be generated with a higher brightness, though at the cost of increased optical noise.
An artificial eye might also allow optical zooming, though since diffraction limits the resolution of a system of this size, zooming would at best allow a 3x zoom relative to normal human optical resolution, and since this eye is operating at that level already - and we are effectively hand-waving away the limits of the brain to process the extra data - this would be unnecessary.
Given that the limits of diffraction in this system are relatively large, the sensor chip may incorporate a number of sensors in an area represented by a 20-arcsecond field of view. This would include the usual Red, Green and Blue photo-detectors, but might also include an infrared-sensitive photodetector, possibly an ultraviolet-sensitive photodetector, as well as polarisation detectors.
Why polarisation detectors? These would at a minimum allow the selective filtering of optical glare and reflections of sunlight, providing better vision in bright conditions. Then there would also be the ability to see stresses in various materials... the list goes on, and I suspect that only a person with such eyes would be able to come up with a complete list of the advantages.
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I'll do a science light version since I hate that type of writing, but this should still be useful as I IMHO cover some important points.
**Not a problem**
The specs for the human eye are not actually, with few exceptions I'll return later that good. It just happens to be attached to what is probably the best visual post-processing and data aggregation system we know. Seriously, your brain is totally awesome at processing visual data. Optical illusions are based on the wide gap between what we actually see and what brain interprets we are seeing and I once spent few days reading on the topic and I was continuously impressed by amount and efficiency of the processing going on.
**Use the system, do not replace it**
Since the processing part of the visual system is very good and probably will remain beyond our ability to improve for some time and at the very least can't be improved without requiring a long relearning process which probably would only work on children or people with medically boosted brain plasticity with all its potential problems... Just tap into the relatively low bandwidth data path already there and add some control on top of it.
Since you presumably have a brain link the system will be able to tell when you want to focus on detail and then you want to widen the focus. You can link that to a digital or even optical zoom. Eye already can adjust focus somewhat so extending it should be simple enough and not confuse the brain too bad.
Similarly the already existing, and actually pretty good, ability to adapt to lighting can be boosted by simply making it work faster and by extending the low end to actual light amplification. But accelerating the adaptation is the main point, the eye is sensitive to glare and adaptation is actually a physical process that has noticeable lag. (Although as said, humans with their adaptation to forests with bright sunlit spots and deep shadows actually already are pretty good.)
**Bit depth**
Current 8-bit RGB really is not good enough. We can perceive something like four thousand levels of luminosity, IIRC. This means that fooling the eye to think that an image is real and has continuous gradients requires 12-bits of color depth. In practice 16-bit color channels would probably be needed to also mimic the light adaptation ability. So the camera would need to have roughly twice the color depth of the ones in mass market use. I see no issue building such camera by 2050.
**LiDaR**
Low-light ability possibly with active infrared is mentioned. I'd instead recommend using RGB LiDar which would allow very accurate depth vision and produce a full color image. Essentially both eyes would incorporate RGB LEDs or similar efficient and fast light sources which would then produce very short double pulses of monochromatic light one eye and one color at a time with much longer pauses between the pulses.
While the overall light produced would be low the eyes could be optimized to detect the bright if brief reflections produced and use those to produce a full color image independent of ambient light. As a side effect very accurate perception of 3D position and movement would be produced that possibly could be fed directly to the part of the brain responsible for building a model of our surroundings. This would produce superior spatial awareness within the range of the LiDaR.
**Make it extensible**
What you can fit inside the eye is limited. You can't fit advanced optics for telescopic sight without compromises, light amplification beyond the "cat level" and thermographs, active infrared and ladar/radar with real range require cooling and power that make them impractical for implant.
But you can still have them! Just have an external accessory with its own powersource that attaches to the forehead, helmet, or shoulder. For some uses carrying them in the hand is possible, for active infra-red a flashlight would be quite sensible solution. Even a tripod can be used in extreme cases. Just have a low powered and short ranged wireless protocol and enough processing power that the extra data can be integrated.
A classic example would be the telescopic and light amplifying scope attached to a sniper rifle. Your eyes would directly mark the aiming point in your field of vision without having to look thru a scope. And if you focused at the distance your vision would smoothly without perceptible transition go from the close and wide vision provided by the eyes to the narrow but long distance view of the scope. Data would be simply integrated and **available** for use. Such smart gun systems are the norm in cyberpunk settings.
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Yes, we have the technology (for A) or we have enough knowledge to invest in engineering the technology (for B).
**A**: I recall a presentation on YouTube concerning making a device that is attached inside the retena and stimulates the nerves. The case is made of diamond, with conductive leads and non-conductive case all seemless one-material! (Diamond is a semiconductor like silicon.)
It *works* and was in prototype. It can treat the two leading causes of blindness, which affect cone cells but leave the nerves.
So, go wild, with any kind of sensor not limited to human vision range and image processing, feed into the retina as if viewing a display.
**B**: a long time ago I recall reading that the communication ptotocol used for the layers of nerves on the retina to deposit down to the optic nerve has been reverse engineered. It is *possible* to make a bionic eye in the Steve Austin (TV, not just book) manner, and plug it in. If we could connect the individial nerves in the bundle, if we could attach to them at all in a permanent and reliable manner. That's the bottleneck of *all* ennervated prothetics, and if we could do that we'd have robot hands and legs first.
It's easy enough to make the nerve-connection plausible in fiction. Most people don't understand why it's not already a thing now! It *seems* simple, and looking up some experiments in popular press will give you ideas of what to write: just pretend one of those ideas worked, or the issues have been solved.
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It's not hard to imagine genetical engineering getting to the point where we can grow extra limbs, or design animals/animal parts from scratch. I was wondering how we could integrate custom designed body parts into our nervous system.
Let's take a basic example of a pair of angel wings (giant bird wings). Let's say we can successfully grow these in the lab ready to be used by a person. Even if we were able to grow a sort of connection port on the wings, which we surgically implant into the human's spine and it is able to fuse with our spinal cord, would we be able to control the wings or would they just be dead weight? Assuming that we can't control them by default... **What can we do to allow these extra limbs to be precisely controlled by their owner?**
* Should allow full functionality and precise control
* Method should work for any kind of limb that we attach
* Should have no side effects such as uncontrollable leg movements
* Don't worry about integrating blood circulation
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This is an interesting question from a couple of different perspectives, as there are both gross physiological and neurological changes that need to be made.
The first issue is nervous integration. Your body has a set number of nerves in the spinal column that are connected all over the body. There are a *lot* of them, and they all go somewhere, so you've got 2 (really 3, but I'll get to the third later) options here: 1: co-opt some nerves that already have other functions and accept that you'll have issues elsewhere in the body or 2: Grow a whole new set of nerves that connect directly to the brain.
Then you run into the next problem: Neurological integration. While it's possible for people to learn to do new things with nerves they've already got (option 1 above) it's tricky and takes a lot of time as the brain has to 'forget' how it worked before and forge new neuron pathways. I imagine it will take even longer if you're just bashing new nerves into the brain, though with the level of bioengineering you're suggesting forming a section of new neurons specifically to cater to those nerves shouldn't be too much of a stretch, and therefore the new neurons will be able to 'learn' the new skills from scratch, rather than having to overwrite old pathways and patterns of behaviour.
Now we come to option 3, which I think is possibly the coolest option. The brain, in essence, is a learning machine that maps inputs to outputs. We're starting to get a handle on how best to do this with machines, and your society seems a bit more advanced than ours. so:
Integrate a small computer directly under the brainstem, linking the old nerves to the new nerves, but with a configurable pathway arrangement controlled by a (hideously complex) learning machine. The person can then be challenged to a series of tasks and stimuli to allow the machine to learn their normal responses and how certain tasks match to certain nerves. The machine is then in a position to 'map' those tasks/stimuli directly from the persons brain to whatever format is most appropriate for the new limb. If built correctly it can start a process of constant upgrades/tweaks to optimise the new limb for the new user and allow for configurable remapping of nerves on the fly (as it were).
If a switch (mental or otherwise) is included to allow the user to flick between states, the machine can handle all the mappings required for turning on/off limbs, and also keep limbs that aren't currently being controlled still (for example if you want to hold something and use your wings at the same time)
And coolest of all: If someone else has learnt to use a particular limb you can upload their mappings to your unit, and have a massive headstart on learning to use the extra parts.
Though I don't look forward to the day someone learns to hack it...
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It seems safe to assume that a person would not be able to control an extra limb immediately, especially if it was something as unusual as wings. But given some stimulation, i think a human would be able to learn to use those new features.
This assumption is first based on the obvious: a new human learns to use his libst over time, with some trial and error.
But as [this](http://www.scientificamerican.com/article/device-lets-blind-see-with-tongues/) link (*seeing with your tongue*) shows, a grownup can learn new tricks with his nervous system, too.
So i would assume that for something like wings, an adult would - after the implanting woulds have healed - need some months, maybe up to two years - to learn to make use of those new body parts.
As far as wings are concerned, be aware that winged animals have very strong muscles in their chest to operate them. You may want to bio-engineer those muscles together with the wings, especially since you need the original chest muscles for arm movement.
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**With Ganglia**
If you want to reduce the amount of I/O to the new body part, equipping the new part with some specially designed ganglia is really the way to go.
[](https://i.stack.imgur.com/F7AyV.jpg)
A ganglia is like a tiny special purpose brain. In humans they control things like reflexes. When the doctor taps on your kneecap, that sensory information goes to a ganglia and the ganglia issues the command to kick before your brain even gets news of the impact.
By using complex ganglia in the new body parts you can reduce the amount of fine motor control required to use the new body part, this in turn reduces the number of new nerves or brain realestate required to run this new part.
How to get those signals out? Use a **Brain Gate**.
[](https://i.stack.imgur.com/S4prw.jpg)
This is a very small array of electrodes placed on the cortex of the brain. Which, over time, your brain learns to interact with. They are used today for locked in patients to control robotic arms. Mind your googling for it if you're squeamish about brains and blood.
**For instance with wings**, an embedded ganglia could more accurately and rapidly make minor adjustments for stability or major flight operations entirely. It allows your brain to make a much simpler command like 'flap' or even abstracted as thinking about pulling yourself up by your bootstraps in order to fly up.
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In addition to Neurological control, you have to consider how the limbs physically operate. There are two main concerns: Limb Upkeep, and Limb Control
## Limb Upkeep
Limbs get scraped, bruised, broken, tired, diseased, frostbitten, burned, and probably many more things. Either the limb is like any other limb - healing itself for the most part and receiving energy to maintain itself through your diet, or it needs to be "charged" (*Probably chemically*) with the energy it needs. (*Or, if it's more like a machine-limb it might just need repairs occasionally along with being charged electrically*)
Assuming the new limb is receiving energy from you like any other limb, moving this energy to your new limb is not free. You'll need to be able to eat and digest enough food to keep up with the energy requirements. (*You mentioned not to worry about blood circulation, but that would tie into here as well*)
This is why there will be a practical limit to the amount of limbs someone has before you're replacing just about everything in the torso. (*Though I'm not entirely sure where this limit lies*) The human digestive system will only digest so much food - even if you're constantly eating.
## Limb Control
The muscles for all our limbs are not like separate boxes you can just attach onto a torso and expect to work. The muscles required to control a limb generally extends a good deal into the torso and other systems to work smoothly with the entire system.
What this means is, some of the muscles to control the limbs must be built into (*and not just around*) the existing structures to create a truly natural limb.
The wing example, would probably not just be a connection of a port, but rather an integration of the wing and the person's chest, back, and maybe even their arms - likely resulting in surgical changes of the entire upper body to create a complete well-flowing attachment. A person wants a total of 4 arms *and* wings? It's going to need even more work to get everything flowing together right.
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I'm curious about the impact of having a moon composed primarily of a material with a strong optical property: calcite, diamond, glass or something else similar. Would the traditional spherical shape pose any dangers in terms of magnifying the light coming from the sun?
What if it was actually a lens shaped moon?
Would a Solar eclipse be a giant-moon-ray apocalypse type scenario?
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Even if you did have a moon made completely out of carbon, it would *not* be completely made of diamond. You are neglecting the role of gravity here. You are expecting a highly refractive, transparent cosmic body which is not practically possible. Only the innermost layers would be composed of diamond, the outer layers would be buckminsterfullerene powder or huge layer of opaque graphite. Furthermore, the asteroids hitting the surface would be depositing a large amount of opaque dust on the surface which would further decrease it's role as a colossal lens.
A lens shaped moon-sized body is not practically possible due to gravity, which tends to squeeze things in a form where most matter can be compressed in a shape that has the least surface area. It happens to be a sphere. A lens shaped body has a much larger volume to surface area ratio. The sides of this lens (even if it happen to form) would be crushed in and after sufficient amount of time (a few hundreds of millions of years), it will crack into a spherical form we see today.
Even if you *did* have a colossal lens shaped body (extremely improbable) which tends to be made of transparent material (severely improbable) which also happens to be at 90° angle against a planet (next to impossible), still the chance of getting metal-boiling temperatures would be very low, because, as you know, the planet surface would have to be exactly (or a few hundred plus or minus) kilometers to the focal point of that colossal lens.
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Assuming that the objections noted by YoustayIgo about the form of the material being transparent don't apply (lets assume a bored god decided to play marbles), and also assuming that the material is cold and not going to undergo heating due to compression (as radiating objects are, to all intents and purposes, opaque in the wavelengths they radiate) it could be possible to engineer a situation where it could be an [issue](http://cdn.c.photoshelter.com/img-get/I0000pJoh36OLdGQ/s/600/600/PHYSICS-OPTICS-glass-sphere-1.jpg) at certain distances from your transparent planetoid.
On the other hand: You've got to have a seriously bored god on your hands to engineer such a situation.
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One short note, that will make you question the transparency of the planet-sized bodies. Transparency is defined as the relation between the intensity of passed through and incident light. It is always in the range [0..1], and is 1.0 only for the ideal vacuum. Solid materials have much lower transparencies, for example optical quartz glass plate that is just 10mm thick has transparency of about 0,999. 1 meter plate will only transmit 90% of the incident light. This is a part of why we use thin lenses anywhere.
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