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[Question] [ Imagine an Earth-like society that has developed into the digital age. They have computers, the Internet and most of the conveniences of the modern age, but they still use a significant animal workforce for: * transporting members of the society over land, sea and air; * transporting goods over land, sea and air; * supplying power to their electronics; * performing actions that in our world are done by heavy machinery like harvesting crops, manufacturing, large-scale construction,... In effect, you got the Flintstones, but with modern materials instead of everything being made of stone. In addition, they have very good reasons for using animals that aren't grounded in superstition or religion. What would these reasons be? The animals can be different from Earth, it's just the society that's earthlike: no magic, sentient being who are inventive and full of resolve, and the entire world is in contact with one another. [Answer] So, this is actually fairly simple to answer. Limit the strength of engines and machinery but allow the development of electronics. This means they can use machines for doing detailed work (like creating computers) but not for anything that involves "heavy lifting". There are a number of ways that this could happen, just having them not invented seems very unlikely so I would suggest instead that materials are the problem. If there is no good materials available for making decent metals or seals (so poor quality rubber and steel or iron) then machines would not last very long if set to doing anything demanding. Cars might exist but they would shake themselves to pieces by the time they've done a thousand miles. Engines would be constantly springing leaks and spraying oil everywhere, etc. In order to do this I'd suggest having iron in very short supply in this world, you could also look at the other materials we use in a similar way and see which of those you need to restrict but iron would be a good start. No steel, no cast iron furnaces, limited blacksmithing. Basically everyone is stuck with bronze tools and they do not hold up so well. I'd also restrict access to high temperature fuels, have wood that burns at a lower temperature and either no coal deposits or also burning cooler. With limited access to high temperatures again it becomes hard to work with and develop advanced metallurgy. You would need to hand-wave a bit how they come up with the wires etc for the computer processing but you can do a lot with copper and glass. [Answer] Having technology is really cool. But most of the time, your technology still requires power. So, the answer is simple: On this planet, there is no source of energy that would be cheaper or more abundant than an animal's workforce, or it has been used up a long time ago. [EDIT] following NZall 's comment: To explain away wind and solar energy, it could be that they used up their fossil fuels before they invented smart grids and a feasible means of storing energy, while the labour of beasts can be "switched on and off" when needed, so they don't have to store energy (other than sunlight in fodder) [Answer] A possible straight forward answer for this is that fossil fuels - (or at least oil) - do not exist or were never discovered or the process for refining them was not discovered. This would make it difficult to drive the big machinery that you need for heavy lifting. [Answer] It could be an environmental factor limiting the size of machines. The atmosphere might be filled with acid, fine grains of sand or something else that is harmful to machinery or just metals in general. There is a process to shield objects from this effect, but it is expensive or otherwise impractical to use on large or moving structures. The animals and people would be evolutionarily adapted to the environment however, and suffer no ill effects from it. [Answer] They have suffered a catastrophe in the past that caused vast numbers of deaths specifically linked to technology failure and they have good reason to believe that the same might happen again. This time they will be ready with a backup system that doesn't need oil or cables or broadcast power to work. However an animal-powered transport and power network cannot be kept in mothballs and wheeled out when needed. The infrastructure of stables, farms raising animals and growing crops for animal feed, and people such as riders, drivers, grooms, veterinarians and blacksmiths, all needs to be permanently in place. So they have made a virtue of necessity. Everyone extols the virtues of a slower pace of life, the opportunity to interact with these magnificent animals, and the job opportunities available for many people who had little useful role in their previous more mechanistic society. I would imagine it would be a point of status to show that you could afford to travel by horse-drawn carriage at a leisurely pace rather than being rushed around in a fume-spewing box as if you were some peon who had to come running when the boss called. [Answer] An unpredictable environment. Adaptable lifeforms. If you look at all our machines, they all need a carefully controlled environment to work as intended: * Cars need a sturdy flat surface * Planes need obstacle-free airspace without major disturbances * They need a constant supply of very specific replacement parts and fuel/lubricants to run * Dont take the environment into account much (they just assume that we humans ensure the environment is ok, if its not, they suffer some catastrophical failure) What separates animals, is that they have evolved to adapt to a more dynamic environment. They might be able to survive on multiple food sources, maybe even without food for a while. They will be able to avoid dangers and work around novel obstacles. Further, you can specifically design your lifeforms to be extra-adaptable (smarter, adapted to wide range of environments). So, what features of the environment would work here? * Rough uneven terrain, which can shift around or break under your feet if youre not careful (think random caves, quicksand, mud, structures formed of weak organic material...). * Lots of dust, particles, sharp rocks, random chemicals, random strings and webs of some material, that will mess with anything that didnt specifically evolve to this diverse environment over millions of years. * Highly varying temperature, humidity, other weather patterns, over both space and time. * Diverse lifeforms that will crawl in your machine, attack it, eat it, or do something else, because it doesnt have the advanced techniques that the beasts of burden have developed (even if thats just "not being a clumsy noisy machine built of delicious iron"). * Varying access to resources / locations, so having a production chain with a dozen steps in it, to keep things functional, rarely works at scale. Of course, you cant be extreme about this to still allow for computers. This isnt even necessary if the other factors make machine impractical, though. But, I would like to emphasize, that the point of "unpredictable environment" is that you can't simply list out all the features. Thats what makes it unpredictable, and thats why you cant build a machine and infrastructure that works properly. Not with your limited knowledge (compared to what the beasts of burden carry in their biological design) If you want to harm production of machines (not just practicality of machines), you could give computers an advantage by ensuring that theres plenty of materials for them, and that the computers themselves dont break and are powerful (so you dont need many, and you dont need a constant supply). [Answer] ## Ethics and Morality Long ago this world was swept by war and destruction. The "winners" of this apocalyptic war found themselves alone in a vast wasteland. Vowing to ensure that the world would never again be destroyed by war, they outlawed any and all non-biological energy generation and storage. --- ## Risk Ages ago terrifying dragon-like creatures evolved with the ability to feed on raw electrical energy. In a never ending cycle, the dragons would destroy most of the world, then sleep for generations while the planet was rebuilt. Realizing that the dragons would awake when power generation levels exceeded a certain threshold, the people of this world came up with an interesting strategy for assuring that the creatures never awake. --- ## Oxidization This one might be a bit of a stretch, but maybe their atmosphere is SO rich with oxidizer that any electrical discharge could cause a catastrophe. Or maybe some imaginary element's presence in the atmosphere makes energy generation impossible (e.g. unobtanium gas) because all of the electrons are lost to oxidization before they can be used. [Answer] Lots of answers here already but I'll throw in my two cents. Maybe their technology has just gone in different directions from ours. We tend to think of all technology as being on the same scale. It's easy to imagine a society that is more primitive than ours -- just look at our own past. It's easy to imagine a society more advanced. But we tend to think of all sorts of different branches of technology on the same timeline. Like, nuclear power is a mid-20th century technology, and television is a mid-20th century technology. So we think that a society that has television would also have nuclear power and vice versa. But who says? Perhaps people on another planet would be far ahead of us in one area, but far behind in another. Perhaps their electronics is very advanced so they have artifical intelligence and android robots, but their medicene is way behind so they have no concept of organ transplants and no drugs beyond herbs that people find in nature. Maybe they use advanced robots to put leaches on patients (or whatever the equivalent is in their biology). This would be problematic in some ways. Technologies depend on each other, sometimes in ways that aren't obvious unless you know the whole history. Like, early computers were in many ways based on tabulating machines, machines that would read punch cards and calculate totals. Those tabulating machines were based on principles developed for looms, to make cloth with patterns in it (jacquard looms). If our society had never seen a need for cloth with pretty patterns rather than plain solid colors, we might never have invented computers. Or at least, they would have had to have a different history. The idea that a society could invent electrical and electronic devices, but never invent internal combustion engines, doesn't seem all that far out. You could explain it based on available resources. Maybe the materials to make computers are plentiful on this world but petroleum is rare to non-existant. You could explain it based on need. Like the old aphorism, "Necessity is the mother of invention." Perhaps the people on this world never perceived a need to travel very fast or very far. Like the population is small and everyone lives close together, and the people aren't all that curious about exploring the rest of the world, so the few people who travel and explore just don't create enough demand for advanced transportation technology. [Answer] > > They have computers, the Internet and most of the conveniences of the > modern age, but they still use a significant animal workforce > > > You've just described modern day planet Earth. Although you and I obviously have computers and internet, consider that a significant proportion of the planet still does not have these things. Yes we in the more developed part of the world have cars, iPads, dishwashers and robot vacuum cleaners, but there also millions of people living in a far less technologically advanced world and thus still rely on animals for things like: Agriculture: [![Agriculture](https://i.stack.imgur.com/FGr1U.jpg)](https://i.stack.imgur.com/FGr1U.jpg) Transportation: [![Transportation](https://i.stack.imgur.com/7pX3T.jpg)](https://i.stack.imgur.com/7pX3T.jpg) Construction: [![Construction](https://i.stack.imgur.com/Ib3m6.jpg)](https://i.stack.imgur.com/Ib3m6.jpg) So in your world the answer to how high technology can exist alongside more primitive use of animals can be the same as on Earth - the modern technology is not evenly distributed. Maybe, like Earth, this is due to the economic model in use - or perhaps other religious or social conditions have divided the world into technological "haves" and "have-nots". [Answer] As others have said, no fossil fuels. That makes it quite difficult to get energy into a portable form. (Look at range limits of electric cars, for instance.) You wouldn't really have a pure no-mechanical-transport system, though. You might have e.g. electric trains for long-distance travel & urban trolleys (as in much of Europe), or heavy equipment that could be run from electric cables, like some mining equipment. Limited air travel would be possible with biofuels, but would be more expensive. (Just not possible to do with animals, barring 'magic'.) So for local transport, and work on small projects, you're back to horses &c. If in addition you have a lot of rugged terrain, that's another factor. I can ride a horse in a lot of places where I wouldn't drive even a 4WD vehicle, or even take a mountain bike. [Answer] Sort of exotic, but maybe noise reduction? These guys might heavily rely on hearing (like we rely on sight), or maybe their world has some apex predator or really nasty vermin that are attracted to sounds. Anyone, no one there thought that developing a lot of noisy combustion engines was a good idea. [Answer] Rather than assuming that the subjects did not discover how to apply principles such as combustion and electromagnetics to create engines and motors, suppose they did (or at least are capable of doing so), but they cannot practically implement them on this world. While some of the other answers cover this possibility (such as Tim B’s limited materials answer in the vein of Asimov’s Foundation), based on the Nzall’s question we should also look into why someone who has the materials would instead choose to use beasts of burden. Consider some of the reasons why we use machines in the first place. They are mass produced, they efficiently convert fuel into motion, and they never tire. Notice also that production time is always shortening and fuel efficiency is on the rise (as well as effective fuel discovery). For earthlings this usually means that, economically, the Ford pickup truck beats the oxen and the charger beats the thoroughbred racing horse. In another setting however, suppose the beasts of burden could be mass produced, they fueled themselves (or very little effort was required to feed them), and their stamina was boundless. In that instance machinery would be ignored in light of a more profitable investment. As far as what this could be, consider anything from giant insects to plant-based beasts of burden. These reasons work especially well for air travel, since that took us a LONG time to develop, but the animal kingdom has had it down for as long as we can remember. Compare this to computers, which can take far less resources per unit (although production usually does involve intensive industry). Where engines and motors are used for things they do better than animals, these are used for things animals simply can’t be trained to do. As a result, people with unlimited manual labor resources can still see advantages to electronics. Also, while superstition and religion are specifically set aside in this question, culture is not. In many European countries air conditioning is readily available, but unused; they simply have different tastes. If this society were to view machines as heavily polluting, noisy, dangerous, and distasteful, then I see no reason why people in our exact situation could not have chosen a “more green” world dependent on animals instead of machinery. I feel however, that this is close to the border of how subjective an answer can be before the moderators start to frown at it. [Answer] The issue to be overcome is not so much in powering things as producing them. According to this [paper](https://www.princeton.edu/~ota/disk2/1988/8808/880809.PDF) (citing a Dept of Energy report) copper production takes 81.9 -106.5 million btu per ton, approximately 39301 horse power for 100 btu. Hauling, the most easily replaceabe by animals takes 13.14 million btu, so you would still need to produce 25545-33406 horse power per ton. Using animals for this presents a number of challenges. In addition to the sheer amount of power needed there are a number of issues. Firstly there will be an upper limit to the amount of power one animal can produce, given that there will also to be an upper limit to the size of an animal, before it can no longer support itself, and I suspect the amount of extra power diminishes as it get larger. So we can't escape having to use very large numbers of animals. Secondly there is the question if how to convert animal power to a usable form. Here we will be up against the inefficiencies/loss brought about by conversion to a usable form. A large of the energy consumed in existing copper production is likely to be in the form of burning fossil fuels directly in smelting etc, so there would need to be much more energy consumed in their absence. A useful comparison here is aluminum smelting which is powered by electricity. There are very few aluminum smelters in the world since they can only be sited in places with an abundance of cheap energy (usually hydro-electric) and an easy way of getting enough raw materials (by boat). This will be a very difficult scenario to overcome. The existence of electronics on a mass scale is is likely an indicator not just of a technologically sophisticated society but also an energy rich one. There are two ways I can see this happening, a post-industrial world and a trader planet. In the first scenario the planet followed much the same energy rich, technologically sophisticated path that Earth is on. At some point however they hit ecological limits and/or (mostly) ran out of feasibly extractable resources/fossil fuels. At this point society transitioned to one where the source of nearly all raw materials is recycling (which tends to be much more energy efficient) and there is a very limited power supply. What little energy dense fuels there are left must be strictly rationed to support vital uses. Since this would also put a limit on production it makes sense to use non-technological means (i.e. animals) wherever possible. In the second scenario the planet lacked (energy dense) resources, with one important exception, but was still able to develop a culturally and socially sophisticated society despite, or perhaps because of this (this is implicit in having things like the Internet). However it turns out they have a near monopoly supply on feasible amounts of a resource that is much in demand in other societies on other planets (think Coltan) that might not be able to produced elsewhere in great amounts. Thus they were able to trade technology with other planets in exchange for this resource. [Answer] They might not have developed the technology to grow meat or products like milk or eggs without the use of animals. They could set up vast agriculture systems to produce cattle, chickens, etc. to assume these tasks. Computers could be extensively used in the automation and even design of the agriculture factories but the physical work of actually growing the meat would be left up to the animals. [Answer] It could be a cultural/religious thing, like the Amish. I know - you said that it shouldn't be a superstitious/religious thing, but in my experience, Amish people don't use certain technology for pragmatic/community based reasons more than for religious reasons. Many Amish families families DO use technology. They use telephones, they use diesel engines in mills, battery powered tools, cash registers, and propane refrigerators, and when they hire out to do work for the English they ride in cars as passengers, and some groups of Amish use tractors on their farms - So they do use technology, but they also use animals for many things that we've replaced with mechanical tools. They're very selective about what technology they use, with the idea that what they use shouldn't impact their way of life, but instead protect it. I'm not an expert on Amish thought, so I can't say exactly all of their reasons, but here you're just looking for a reason for people to do or not do something - and the Amish people's philosophical model of not using a technology because it doesn't fit within their community might be a good fit. It's not that they can't do it - they just don't believe that they should. [Answer] This is simple - your world is an ocean, with thousands of small islands close together - Islands just big enough for one or two farms - It is easy to lay cables across the small stretches of ocean, but it would be impractical to develop large machinery, as it would be difficult to move it from one island to another, and it would have limited use on one island. On these small islands, there would be no point to having roads, or cars. Because animals are need for food production, almost all the land must be devoted to feeding the animals. As such, the animals are also used for transportation and energy production. With the land devoted to farming, there is no way to make other energy production facilities. These islands never had the chance to develop oil rigs, iron mines, large ships, highways, roads, or cars -none of those were ever needed. There was no point in trying to get fossil fuels, as nothing used them. There was no point making a gas or diesel engine, as petroleum was never discovered. There are few trees on these islands, so the wood is used mainly for building houses and barns, rafts, and some small ships. On the largest of the islands, there was a rocky hill. Blocks of stone were cut from this hill, and used in mechanical processes. Some were made into millstones, some were used as counter weights for pulley systems. One day, as stone was being cut, some random dude discovered copper. The people of the islands liked the cool looking shiny metal, and did lots with it. Someone decided to make really thin strands of it, and wrap it into a cable, as these new copper cables were much stronger than ropes. A common method for processing grain was putting livestock in a hamster wheel and using that mechanical power. One day, another person decided to use this spinning shaft contraption as a winch to wind up the copper cables. Apparently, something strange happened during that process, and he managed to discover electricity. "This is neat," he thought, "I should make a computer!" and so he did. As soon as he had made a computer, Jon Skeet sensed the presence of another electronic device in the universe, and somehow managed hack time and space, manifesting an internet connection long enough to show the inhabitants of this island nation stack exchange. After they had access to [Electrical Engineering](https://electronics.stackexchange.com/), [Stack Overflow](https://stackoverflow.com/),[Physics](https://physics.stackexchange.com/), [Biology](https://biology.stackexchange.com/), and [Mathematics](https://math.stackexchange.com/) (to name a few,) the island nation's technology boomed. New computers were developed, internet cables were established connecting the islands, and all the citizens of the world had access to Stack Exchange. (they lived happily ever after) However: There was still no need for large machinery. There was still no way to power large machinery. There was little to build large machinery out of. There was no practical use for large machinery, as there was no easy way to transport it between the small islands. Livestock stayed central to the economy- The LHWG (Livestock Hamster Wheel Generator) was optimized, but remained the central power production system. [Answer] Animals are huge May be there are really huge animals like dinosaurs, or civilisation was created by tiny creatures? [Answer] # Non-Metallic Planet Not a gas giant, but not a rocky planet, either. Rather, a planet with just light elements, like the first 3 rows of the periodic table, or so. You probably need carbon or something similarly flexible to get life at all, and iron and other trace elements are necessary for earth-based life, but it is at least plausible that exo-life could use something other than iron to carry oxygen. Or, there are only trace amounts of iron on the planet (iron is a rare-earth metal) and most of it is bound up in living things. This prevents you from making anything we would recognize as cars and trains and planes, as their sturdiest construction material would be something like wood (if you have stone, then you have Si, and if you have Si-based electronics, you probably have other heavier metals like Fe and Ni, and thus, cars). # Electronics So, how do you get electronics? Most conductors we use today are metals, Cu to Fe to Au. Well, this is where it gets tricky. This planet would basically need carbon nanotube-based electronics. It turns out that you can make carbon nanotubes using very low tech (pretty much just burn any organic matter and you will get some by pure chance). But how you turn that into electronics without the benefit of metals requires a bit of creativity. On the other hand, without metals to begin with, an alien would be forced to think differently anyway. You could also use [conductive polymers](https://en.wikipedia.org/wiki/Conductive_polymer), or go the biological route and use doped water to make wires. Consider that we already have the most energy-efficient computers in the known solar system sitting inside our heads. # History So, carbon nanotube electronics would be the cutting edge of technology on this planet, while neuro-electronics would be the default mode of computation. They would most likely have bio-computers rather than what we think of as hardware. This would also help explain the energy sources. They would lack the Si and rare earth metals necessary to make PV solar power, as well as the radionuclides for nuclear (no U, Pu, Th, etc.). They would have fossil fuels, but nothing sturdy enough to build boilers, let alone internal combustion engines or gas turbines. The best internal combustion engines you can build with light elements use the ATP cycle and power your muscles. The question then becomes not: "Why do they use animals?" but rather: "How did they get electronics?" At some point, they could likely develop counting and mathematics on their own, and could build basic mechanical computers like abaci from just wood. They may even build primitive machines like a TinkerToy computer to play tic-tac-toe using wood and animal parts (bones, etc.). But at some point, they would realize the need to build fast switches in order to make a truly general computer. This is where things get ugly... In the course of hunting, they will notice that sometimes animals move after they are dead, and they will wonder what causes this movement. Eventually, they will realize that nerves are conducting signals to muscles, and that nerves are actually wetware switches. However, they will also realize that nerves degrade very quickly once their host creature has died. So to exploit the natural wetware electronics, they will need live creatures. In the beginning, they will select animals which are a convenient size for handling, like small rodents. They will figure out how to use stimuli on one end to trigger behavior on another. For instance, they might notice that pricking the paw of a rat causes its tail to move. Or maybe if you price one paw lightly, the tail doesn't move, but if you prick both paws, it does. And now you have the crudest bio-switch (a kind of logic gate), whose energy source is almost any organic matter, but runs reliably on vegetables. You just need to chain them together by connecting the tail to needles on the paws of downstream rats, and you can build a complete ratputer to do simple calculations. # Progress While this sounds terribly cruel, keep in mind that you can't build a decent-size circuit with rats, and these scientists/engineers will figure that out pretty quickly. Also, such a ratputer would be very power hungry (in the most literal way) and produce a serious waste problem. So you need to miniaturize. You then move to smaller and smaller animals, until you can work with, say, ants. Because insects already communicate with each other, you may actually be able to train them to use multiple modes of transmitting information in a computational network. You could use mechanical stimulation for precise calculations (a leg moving could tickle the antenna of a downstream ant), and pheromones for high-level signals. Also, the ants could be explicitly trained to produce certain behaviors (being fed one sugar drop makes its 4 leg wiggle, and being fed a different flavor drop makes its 5 leg wiggle). Over many generations, they may actually be able to create a breed of insect which is specialized for computation! The legs may naturally lock together, forming quasi-mechanical circuits, and the ants may become specialized for their task by increasing signal propagation rate, accuracy, and even adding new functions which would not occur in the wild. Eventually, the legs could fuse together, creating a kind of hybrid creature in which each ant brain is like a local distributed CPU, operating on a mesh of power droplets raining down from above, and releasing waste to a collector plate below. Multiple "compute boards" could be stacked into a 3D space to provide more powerful computation. And since the antennae and eyes and carapace would become redundant, these features would be bred away until the ants eventually formed nearly pure neuron networks with the minimal internal organs to support them, complete with interlocking feeding/respiration/waste plumbing so that they can be packed densely. # Conclusion The limiting factor for all civilizations we know of is energy. Technology only moves forward when energy availability increases. Fire to cook food releases more nutrients for humans. Food for humans powers population levels. Fire to melt metals provides tools for building, hunting, and warfare. Fire contained in metal can be harnessed to power machines. And nuclear fires contained or uncontained can be harnessed to do planet-altering things. If you prevent energy from being harnessed, then you can't plausibly build vehicles or computers at all. So forbidding fossil fuels is both implausible and unnecessary. The only way to prevent earth-like technology is to take away the key ingredients which underlie our tools: metals like Si, Fe, Cu. These give us concrete, steel, and wires. Whatever is left can be used by biology to build alternatives. ]
[Question] [ This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. In my WIP, I have an astropalaeontologist who uses a special device to scan the underground for any macro-size, i.e., visible with a naked eye, fossil remains. This scanner is self-driving and carries out the pre-programmed task autonomously; while slowly driving over the ground of the place of examination, it sends signals down through the ground and translates the reflected signal into a 3D picture, which is then relayed to the researcher's computer. My question is: what kind of signal would this scanner use, and how deep would it penetrate the ground? [Answer] <https://en.wikipedia.org/wiki/Ground-penetrating_radar#Archaeology> Radar has ability to scan for archaeological artifacts, and as been used to detect burial sites. Your scanner is radio transmitter and antenna, and would penetrate the ground depending on the material, from thousands of meters, to less than fifty meters. It is rare but possible to detect fossils this way: <https://www.sciencedirect.com/science/article/pii/S1631068312000796> [Answer] One of the best ways of mapping out what's underground is by using acoustic waves. They'll travel through pretty much anything and reflect off buried objects or interfaces between layers of rocks. All you need is a sensor sensitive enough to pick up the rather faint return signals. A technology you could use here is [distributed acoustic sensing](https://en.wikipedia.org/wiki/Distributed_acoustic_sensing). This involves laying a fiber optic cable along the ground and firing a laser through it. Details in the way the light scatters back up the fiber can be used to detect even the most faint, microscopic movement in the cable (including the tiny vibrations of an acoustic signal). [Researchers have used](https://eos.org/articles/unused-fiber-optic-cables-repurposed-as-seismic-sensors) this technology with unused, underground telecom fibers where it's proven sensitive enough to "hear" pedestrians walking through several meters of earth, and can even hear echoes from the seismic waves of earthquakes thousands of kilometers away. Geophysicists use this to perform [vertical seismic profiling](https://en.wikipedia.org/wiki/Vertical_seismic_profile), where they bury a fiber vertically and use it to build detailed maps of underground formations and structures. Your character is on the move so burying a fiber optic line isn't practical. Instead, have your automated survey vehicle lay out the fiber horizontally across the ground. It could then use something like a [drop hammer](https://www.geotools.com.au/product/title-4/) to generate a seismic wave and listen for the results. Repeat this process from several different points and you should be able to build a detailed 3D map of everything that's underground. You won't get a very good signal without burying the fiber so your range will be somewhat limited, but you should still be able to measure far, far deeper than the deepest depths that your archaeologist could reasonably excavate. [Answer] What kind of signal would the scanner use depends how far you want to penetrate into the earth and what kind of methods you are using to reconstruct the signal. Generally a pulse, or a tone, or a chirped pulse where the frequency changes during the pulse would be used. The ground penetrating radar is sending an electromagnetic (low frequency radio wave) into the ground, and the amount of reflection you get back depends on the how conductive the material (dielectric constant) of the material. So it is looking for differences. Your fossil would be a slightly different material than the surrounding rock. It would also be sensitive to voids, or groundwater underground since it changes the nature of the material. The resolution is usually not that great, but good for archeology trying to find where buildings used to be, rather than small objects. If you want to use acoustic methods, it would be more difficult and you would probably have the scanner put stakes into the ground to act as emitters and detectors. This is to match the impedance so the sound energy goes into the earth rather than reflecting off the surface (like putting jelly on an ultrasound probe). Again the resolution and depth would depend on the wavelength (frequency) of the sound. A shorter wavelength you can get higher resolution images, like the ultrasound used to monitor pregnancy, but the high frequencies don't go that far. But it might be a story element to be able to hear the scanner sending pings into the earth. When a submarine pings something underwater you can hear it and depending on the type of sonar may hear something like a short ping and echos, or something like a slide whistle. In your case, the signal might sound like a bunch of clicks, or as the scanner varies the depth it is looking at the pitch of the clicks or pings might be higher when looking at the surface and lower when looking deeper underground. For very large objects underground like salt domes or oil fields geologist will set off explosions and try to map out the structures. For both the electromagnetic and acoustic methods to get really good images it takes a lot of computation. Usually image quality goes up with the number of detectors, or number of scans that get taken. [Answer] In archaeology we tend to use three different remote-sensing technologies: 1. Ground Penetrating Radar (GPR) 2. Resistivity 3. Magnetometry GPR will effectively detect the difference in density between two objects, and can detect multiple objects on top of each other. The depth is typically several metres and the horizontal resolution is tens of centimetres. Although the more money you pay the better the resolution. From these signals you can create a "pseudosection" which is a 2D slice or a 3D map of the subsurface as if you had dug it. Depending on soil conditions you might be able to spot something of a couple of handspans in size. So you could perhaps find a velociraptor fossil but not anything much smaller. Normally with GPR we look for things like grave cuts and coffins rather than the bones themselves (fossils are usually a bit too old for archaeologists - we leave that to the palaeontologists). Magnetometry (well, fluxgate gradiometry which is what I have used) uses the difference in magnetic fields at the two ends of a tube, measured in 10ths of a nanotesla. This is good for detecting metallic things and burned things, but also stones that have been placed deliberately like a wall. The depth of penetration depends entirely on how strong the magnetic field is relative to the top of the tube. Solar weather can affect results, and once we even detected a low-flying fighter jet that flew over us! Resistivity puts an electric current through the ground and measures the resistivity (which is resistance over distance). Typically this penetrates half the depth of the distance between the two probes, but that's more like it's focal point, it will detect changes in soil moisture at all depths but with a square falloff with distance from the focal point. This detects differences in water content and is great for finding filled-in ditches and postholes, wall foundations, grave cuts, that sort of thing. There are other technologies used, but they tend to be of lower resolution and fairly specialised in what they are designed to detect. We generally use all three of the ones I've mentioned in concert, overlaying them and squinting at the results to find general features. The we combine that with our expertise to decide the most suitable places to dig to get results. But we tend to deal with the human, so we're looking for walls, ditches, and buildings rather than fossils which by their nature are made of the same stuff as the surrounding stone. Searching for "archaeological prospection" and "archaeological remote sensing" will yield a lot of pictures of the current state of the art. And Historic England has a [page](https://historicengland.org.uk/research/methods/terrestrial-remote-sensing/geophysical-techniques/) describing these techniques. ]
[Question] [ The setting of my story is a medieval refugee community that has found a protected place to settle. They end up remaining in isolation for a few hundred years. The protection is a boost for life, in the sense that their crops that can grow there, and they are able to heal diseases with greater skill. It possibly goes as far as to provide them with an abundance of fish or wildlife for hunting and strong animals will populate their own livestock. At first, I thought it would make the most sense to make their technology level more like an ancient or nomadic civilization. But my research and imagination have come up short on that one and I'm wondering how much of a stretch it would be to keep their technology at a more typical medieval level. Could an isolated society of a few hundred people possibly have metals? Would I need to make it much larger? They live in a mountain ravine with a river running through it and don't venture far from that location until after the start of the story. Edited to add since it is coming up: My starting assumption is that they are almost all involved in farming, animal husbandry, food preservation, hunting, or fishing. [Answer] If [bog iron](https://en.wikipedia.org/wiki/Bog_iron) is available, then a single knowledgeable person would be capable of collecting it and working it into ironwares. Additionally, smelting other varieties of iron ore can be achieved by a single knowledgeable individual, perhaps with the assistance of unskilled labor to operate the bellows. Working smelted iron into iron and steel goods can also be achieved by a single person. So, the minimum population required for metalwork to be practical is 1 knowledgeable person. Having people to whom this smith can sell wares would give the smith the time required to devote entire days to this craft, rather than also having to take the time to grow and cook food and make clothing. [Answer] As [MontyWild's Answer](https://worldbuilding.stackexchange.com/a/221754/37679) noted, +1, early metal working using bog iron was easily accomplished by just a few people. I'd add some details. Thousands of Vikings created [Settlements in Eastern North America (Greenland)](https://en.wikipedia.org/wiki/Norse_colonization_of_North_America) circa 980 A.D. that survived to 1430 A.D. or so. They were active in farming, and many other things, including collecting [bog iron](https://en.wikipedia.org/wiki/Bog_iron#Pre-Columbian) and processing it into steel for weaponry; there have been identified the necessary bogs and soil analysis has identified plenty of evidence nearby of smelting and the kilns necessary to refine the iron and turn it into steel. (several kilograms of discarded slag iron.) That can be done by a few dozens of people, of course they would need to be supported by trade, but the raw materials (bog iron, clay, lots and lots of wood to burn, lots and lots of muscle to hammer hot iron) were free and steel products (including weaponry) were extremely valuable. We found remains of iron nails and straps, for example. It would be a good living. What likely ended the Viking settlements was the [Little Ice Age](https://en.wikipedia.org/wiki/Little_Ice_Age) (1303 - 1860 AD), they were so far North that increasing snow, ice and storms may have made sea travel difficult. It is also possible that in a few centuries they just depleted the bog iron. In any case, the last recorded activity in the area, after much decline, seems to have been after about 500 years of Viking occupation of Greenland, circa 1430; just a generation or two before Columbus. [Answer] # It depends on accessible resources. As others have noted, a single person could do it. But, in medieval times they mass produced steel with a society. You didn't just find iron lying around. You had to make mines, deal with flooding, transport the ores, use water wheels to power bellows and pumps and such. They also had superior creations, like plate mail. A suit of armor might be constructed by multiple workshops, with some using water power to hammer sheets of metal into place, with specialists doing complicated work. If they have accessible iron they can probably do the basics- make spear or arrow heads, nails, a few minor iron tools. They can make a small amount of material, which is pretty crappy. They won't be at medieval level tech though. [Answer] They can collect metal. <https://en.wikipedia.org/wiki/Cape_York_meteorite> [![cape your meteorite](https://i.stack.imgur.com/YtXJY.png)](https://i.stack.imgur.com/YtXJY.png) <https://www.sciencephoto.com/media/1157678/view/cape-york-meteorite> The precontact Inuit knew where there was a big meteorite and they would collect iron from it and work it cold into iron tools. Other groups of Inuit found [telluric iron](https://en.wikipedia.org/wiki/Telluric_iron) - metallic iron from the Earths core and similarly collected and used that. Metallic iron is rare on the surface. Copper is much more common. [![etowah plates](https://i.stack.imgur.com/9NQsI.jpg)](https://i.stack.imgur.com/9NQsI.jpg) <https://en.wikipedia.org/wiki/Etowah_plates> Depicted: one of the Etowah Plates from Georgia. Metallic copper was traded long distances by the preColumbian native people and worked cold. Similar trade and use of copper metal occurred throughout the world. Also for a story it might be more straightforward to have people find metal and bang it with stones into things they want. [Answer] Part of being involved in farming is needing to have metal, provided you have at least medieval tech levels. There are a lot of things you can use other materials for, but for them to last a reasonable amount of time (and thus not require regular excursions to collect more materials) you kind of need metal for a lot of things. Because of this, it was rather normal for any settlement larger than a given size to have a resident smith, almost always a blacksmith or bronzesmith. This actually was not a full-time job, a typical medieval blacksmith in a farming village would: * Help with planting and harvesting at the appropriate times, just like the entire rest of the village. * Help with tending the fields during the growing season when they had no smithing work to do. * Perform yearly maintenance and repairs on the whole village’s tools during the winter months. * Work as a farrier (showing horses) on an as-needed basis, provided the village utilized horses. * Fix any unusable tools throughout the year as needed. * Make new tools on commission as needed (not actually a common thing). It was only once you got to cities, or were dealing with towns that actually had a consistent influx of metal (for example, mining towns) that a smith would be focused on smithing as their sole job. There’s no reason this would not work for your stated setting, you just need the one smith for the whole settlement (and an apprentice so they can keep having a smith each generation). They could also easily manage smelting of iron, provided they could get the raw materials (and possibly with some extra unskilled labor for efficiency purposes). That, ultimately, just leaves raw materials as the limiting factor, and to that, I would like to point out that remaining in total isolation for a couple of centuries is not actually very likely. Villages in medieval times tended to be relatively insular by nature, but even the most far-flung ones would get visited at least once every few years (more often annually) by travelling merchants. It’s relatively likely that your village would have some supply line like this, and that would actually give you a great story hook too (suddenly, the family of traveling merchants that has been serving as their sole contact with the outside world stops showing up, and now they’re starting to run low on the few things they needed). [Answer] A ravine in the mountain is not exactly the most productive place on Earth for farming: most of the people will be farmers, part or full timers. Wood will be easily gathered from the surrounding forests, and if you keep the production low, you might have iron/copper produced for the internal need, provided that the mountains have easily accessible ores. Anything more than that would probably be far fetched for the tech level and the population you are putting on stage. ]
[Question] [ The Red Keep was built thousands of years ago to defend against the invading hordes. The Red Keep itself is a fortress, the main wall of which blocks off the main pass through the mountains. Over the years the threats of the hordes have diminished and migrants from their homelands have begun trying to get into the valley permanently instead of as raiders like their ancestors. Initially the lords of the keep fought off these migrants, but one ambitious lord saw easy money through processing these migrant groups and "employing" them as mercenary bands to defend the keep from enemies within the valley. The Red Keep has been transformed from a simple keep into a large city that's filled with thousands of permanent residents and thousands more going to and from the keep into the valley or the horde lands. How could the lords of the Red Keep properly process such large numbers of people? Note: they do not have access to the printing press. Technology is the Medieval High period [Answer] The way it's always been done... Multi-Level Marketing Erm, I mean... Appointment of Vassals One man can't manage thousands upon thousands of mercenaries. The lords will delegate command over a smaller piece to subordinates in exchange for lawful operation inside the keep, possibly land, and permission to keep a small cut of all mercenary contracts (part of which they need to hand up the chain of command). (modern) Rule of thumb dictates that a superior can effectively manage 7 +/- 2 subordinates. Let's push this up to 10, because 10 is close to the upper limit, and makes dealing with our organization easier. (1) High Lord of the Red Keep (10) Lower Lords of the Red Keep (100) Knights of the Red Keep (1000) Appointed Mercenary Captains of the Red Keep (10000) Mercenaries [Answer] Thousands? Thousand of people during medieval period going to very very very length distance? Not suspicious at all. Not at all. Not like a king would like to know about it. Make some laws. Forbid or invite those people and spread them through whole kingdom. So to answer the question. No, a medieval fortress (or keep or castle or anything that is strictly military) could not process thousands of people. Either the city around the castle is so big it can sustain those thousands of people (which turn the city into one of the largest cities in the kingdom) or it lead to total overrun and fights. To give some historical perspective, during XVI century prosecuted Jews fled from Europe and settled in Poland (with an invitation form King, laws to their settlement, and so on). It was estimated that around 80% of world Jews population lived in Poland. The amount of immigrants was 10-24 thousands (depending on counting method). And this was organised on Kingdom level. Not on some keep captain whim. [Answer] Establish a [march](https://en.wikipedia.org/wiki/March_(territory)), or several of them, out beyond the Red Keep and put the migrants there. Unless the valley has recently had a plague or something, it probably has about as many people as are needed to run it properly. Adding more will just lead to lots of unemployed, homeless people wandering around causing trouble and undermining your social system. If the hordes from beyond the pass want to settle down, they're going to have to find somewhere else to do it. Then they'll have to defend it, although for the hordes that should be no problem. As a bonus, the more land the lord of the Red Keep can bring under his (or his subordinate lords') control, the more powerful he will grow - especially if the king is weak or foolish or has weak or foolish or easily bribed emissaries that allow this sort of thing to go on. On the downside, if the king isn't weak or foolish he's going to put his foot down right quick about any unauthorized colonization for that exact reason. Larger empires in history like the Roman Empire or various incarnations of the Persian Empire tended to be rife with provincial governors and the like trying to build up personal power, sometimes becoming more powerful than the emperors they notionally served, with the attendant intrigues and civil wars one would expect. A related idea you could steal from the Romans is auxiliary service. The hordes from beyond the pass aren't citizens now, but if they serve the marcher lord long enough, they and their families can become citizens and maybe even earn the right to move into the valley if that's still a worthwhile prize. [Answer] An open immigration policy is quite workable as long as you respect certain principles Ancient Rome is an excellent example of a civilisation that administered a very successful immigration program - in particular through its borders and processing (and also integrating) hundreds of thousands of immigrants over centuries. They accomplished this by respecting [certain principles](http://theconversation.com/immigration-how-ancient-rome-dealt-with-the-barbarians-at-the-gate-109933): * An acknowledgement that military might, nor impassable walls, are not solely economically feasible to prevent inevitable migration. Rome was a desirable empire to live: there is economic, social and indeed military advantage to letting them come * They used natural terrain as much as possible to create 'borders' where possible, and only used walls (such as the Aurelian Walls) only where terrain is not adequate - this kept costs down. * They split immigrants into smaller 'tribes' upon entry. These smaller groups were free to travel the empire, but the separation prevented large similar groups from being too culturally diverse * They allocated underpopulated areas for the migrants to live, to ensure not too much load on their infrastructure * A condition of entry was that a certain proportion of the immigrant group would be required to serve in the military and administrative areas, to both increase their army but also to ensure their army was equally diverse, and to reduce costs. * All entrants must surrender their own weapons * All entrants must renounce any previous allegiance Until the Goths, this was a standard policy the Romans employed and provided untold riches and cultural benefits. Furthermore, the administrative and military cost to the policy was mitigated by the requirement of the immigrants themselves to serve as military and administrative personnel. Although Rome was renown for its militaristic attributes, we need to remember that in reality they were very economically astute: keeping costs down in immigration and border control is a key driving force that enables the republic and empire to last the centuries it did. [Answer] WALLS. Big beautiful walls. With gates, written permits with wax seals. What are they for? Restriction and control of certain areas. Restriction and monitoring of movements. The Keep itself, surrounded by the highest, strongest walls will be a heavily restricted area. Only the officially recognized guards, officials will be allowed to enter. Otherwise, only those with written permits by the Lord himself. Customs may be employed that guests can't bring weapons, so on. Town around the keep. It will have smaller walls, not so much for military defense but for better control of normal people and goods. It allows taxation, search for wanted criminals, ... A census can be kept of those with permanent residence and even visitors. A much simpler written permit allows entrance, written by numerous officials tasked to oversee it. Residence permits or privileged can avoid the visitor lanes and enter without undergoing search... or much lighter one. Walls of the valley. A simple wood and mud wall, with patrolling guards are enough to curb movements. Those who must avoid official routes will find ways around it. For simple people, armed guards and fear of death are good enough deterrent. Mini Frame Challenge: Access points, the Gates of Valley, won't have traffic in the thousands every single day. Even if they have, they can wait to be processed. Few people were in that much of a rush, so they can't wait their turn... and those who truly couldn't, obtained special permits in advance (perishable traders, government officials, ...). What they were most concerned in those times, were the movement of masses (they can be a threat), movement of goods or contraband (tax avoided: their money!!!) and a few high interest personage for various reasons (but simple portraits and descriptions of their likeness will be distributed in advance). In case of above average number of travelers, additional guards and officials can be redirected to help with inspections. Otherwise, those without authority or power can wait their turn patiently. Their comfort and needs were rarely a priority or consideration. The farming migrants will disperse into small villages around the valley. They have no reason to be crowded in one place (after their leader offered an oath of loyalty and servitude to the Lord and through him the Country and current Ruler). It is a logistic, hygene and many other nightmares at once. Chinese had big cities, western countries not so much until industrialization kicked in. The merceneries will semi-integrated into the standing army, housed in barracks for better control and their leaders' family "gifted" with permament residence inside the Keep (maybe employed as special status semi servants) or in the Town, with much more restricted movement permits. [Answer] From the lords perspective, you shouldn't bring them in. The best solution would be to allow them to build towns on the OUTSIDE of your walls. Then employ them to build a wall outside themselves. In this way you can extend your rings of protection. Invaders will now need to breach an additional wall and get through the living space of your mercenaries. Over time, trust and trade would be built on both sides of your original wall and the peoples would be come one. But the lords are left with more walled in territory, without unneeded risk. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). Closed 4 years ago. [Improve this question](/posts/148241/edit) As if there was a giant angle-grinder in space that slowly increased its speed. The question assumes that material exists to make this super-disk that doesn't rip apart. What happens as the edges approach light-speed and if it can't, where would the resistance be felt? Could the angle-grinder not produce the torque? Trying to envisage a giant, planet slicing machine. Perhaps the disc could be a lot wider and rotate more slowly. [Answer] This question has actually been well studied throughout the years and is closely related to the [Ehrenfest paradox](https://en.wikipedia.org/wiki/Ehrenfest_paradox). The answer is no-- it's impossible to spin a giant disk in a way such that its outer rim moves faster than the speed of light. First and foremost, it's a rather basic derivation from the postulates of special relativity to show that no object can ever be accelerated to the speed of light. So, any way you might think of to get around this (within the confines of SR at least) must either mean that special relativity is wrong or something is flawed in your setup. As a general rule of thumb: it's probably the latter. Here, the problem is that you are assuming that your saw blade is perfectly rigid, but this is not allowed in special relativity. If we had some perfectly rigid object, like say a giant pole, we could use it to send messages faster than light by poking stuff, which is another no-no in special relativity. Now, a rotating object is slightly trickier-- there is a sense in which a rotating object can be rigid in special relativity, although it differs from the classical picture (see this link: [Born Rigidity](https://en.wikipedia.org/wiki/Born_rigidity)). However, Born rigidity comes with a whole bunch of constraints, one being that the angular velocity stay constant. Clearly this isn't true when you're speeding up the saw, so the blade can't be Born rigid meaning it will be forced to break apart. It's tempting to think that maybe we could get around this with a stronger material, but the point here is that it doesn't matter what the material is. Simply by virtue of living in a universe that obeys special relativity, it can be mathematically proven that what you want to do is impossible. As one final reason why this is impossible-- consider what your disc actually looks like microscopically. It's a bunch of tiny atoms pulling on each other via the electromagnetic force. But the electromagnetic force, like all forces, only propagates at the speed of light. So, even if you did manage to somehow violate special relativity and rotate your saw fast enough that the circumference went faster than the speed of light, the atoms in it would have no way of holding on to each other and the disc would immediately disintegrate. It doesn't matter how strong of a material you have-- the fundamental nature of our universe prohibits you from getting the edge to move faster than light. [Answer] I won't dare sticking my finger into the relativistic theory of rotating bodies, I will just go with the approximation of linear motion, which is valid for infinitesimal rotations. We know that, by relativity, the mass of an object moving at velocity v is increased according to Lorentz factor $\gamma=$$1 \over \sqrt{1-v^2/c^2}$. Therefore, the more the tangential velocity of the disc increases, the more its mass increases, the more becomes difficult to increase its velocity. Moreover, being a rotating body, we also need to take into account the increase in centripetal force, which would sooner or later overcome the resistance of the material. My guess is that the disc will break way before any relativistic effect can be sensed (ask any turbine manufacturer). [Answer] I was once where you are. I wondered if it was possible to create a rotating mirrored propeller capable of spinning fast enough to separate particle pairs in the quantum foam in a manner reminiscent of a Quantum Vacuum plasma thruster. The answer is no. The reason is material stress. Basically the maximum stress on a rotating solid disc (or arm) scales as the square of both disc radius and orbital velocity. This means that long before the edge of your disc is moving anywhere near C the disc itself is being put under stresses usually reserved for... erm... supernovae? Possibly freshly expanding galaxies. Either way: it was a while back when I ran the numbers, but suffice it to say that your disc will have broken apart looong before you get up to these kinds of speeds. [Answer] Millisecond pulsars! Gravity waves! Imperial to metric conversions! 60 mile diameter disc. 188 mile circumference. 1000 rotations per second = 188 \* 1000 miles / second = 188,000 miles/second Speed of light = 299 792 458 m / s = 186282 miles / second. The edge would be going faster than the speed of light; not allowed. Here is a fine and relevant answer lifted from the astronomy stack, which asks about neutron stars. The one is question rotates at 25% of the speed of light. Go visit and upvote! <https://astronomy.stackexchange.com/questions/1291/what-is-the-fastest-spinning-rotation-of-a-neutron-star> The answer cites this wikipedia article <https://en.wikipedia.org/wiki/Millisecond_pulsar> with this text > > Current theories of neutron star structure and evolution predict that > pulsars would break apart if they spun at a rate of c. 1500 rotations > per second or more, and that at a rate of above about 1000 > rotations per second they would lose energy by gravitational radiation > faster than the accretion process would speed them up. > > > The cool thing for me here "lose energy by gravitational radiation". Huh?? I knew about gravity waves but did not realize that the production of gravity waves would allow a thing to slough energy! <https://en.wikipedia.org/wiki/Gravitational_wave> There is the solution for how dark matter sheds accumulated energy on descending into a gravity well - as gravity waves! OK; the saw blade. It will need to go slower. But you can make it out of a handy millisecond pulsar and still have it go plenty fast. [Answer] The only way the edge would spin with an angular velocity faster than the speed of light, is if the momentum from the centre (where I assume you're hypothetically applying the force) is transmitted instantaneously to the very edge. However, since there's no such thing as an instantaneous process in reality, there hypothetically needs to be some transmission (usually through the material of the disc). Imagine, when you were a child, you might have played by spinning a bucket on a rope. You might know that the bucket doesn't immediately align with you spinning at the centre, but lags behind at the start. Then, as the rope is being pulled taut (by to centrifugal force on the bucket), the bucket aligns with your centre. The same happens to any other material. In the case of inelastic items, the energy we previously required to make the elastic string taut is converted directly into stress on the material's structure itself. For real life turbines, propellers, etc..., the material's strength should hopefully be enough to resist that stress, and keep the edge aligned with the centre from the start. Now imagine, that instead of a bucket on a rope, you're trying to rotate a (decently sized) lump of playdoh on a dry noodle. You'll know that if you attempt to rotate it quickly from the start, the noodle will break from having to pull the weight attached to its end. Now, let's examine two scenarios for our hypothetical disc: 1. it's made of solid material. As you attempt to rotate the disc faster and faster, the stress on the material increases to resist elastic deformation not only from conferring the momentum to the edge, but also from resisting the edge's centrifugal force! Given the hypothetical size (and mass) of our solid disc, there is no material known to us that would be strong enough to resist such forces. The material structure binding the disc would disintegrate and it would simply crumble, flying to pieces in spirals. 2. it's made of non-solids. Basically, it would just turn into a maelstrom. The centre constantly spinning relatively faster and the edges lagging behind, trying to catch up. For a real world example with appropriately large energy, consider the ring of plasma around a [quasar](https://en.wikipedia.org/wiki/Quasar). ]
[Question] [ I was reading on another question ([this one](https://worldbuilding.stackexchange.com/questions/117876/effects-of-stray-bullets-in-space)) and was thinking "What if those bullets could return?" What I am looking for is: 1. Practicality 2. Cost effective 3. Combat effective 4. Manufacturability [Answer] Rather than modern "dumb" bullets, you could replace them with "smart" bullets that are actually tiny robots. In Neal Stephensens Seveneves, they have to fight in close quarters in space-stations, so they have to have robot bullets that won't puncture the sides of the station, and instead become temporarily inert if they miss the target. Any kind of similar robot/nanobot, depending on what specific conditions, could be done to launch itself back after a certain distance (such as a bola splitting itself off after a while). Since your bullets may not have to kill, necessarily, you could have the gun provide the propulsion forward and the robot has the propulsion system backwards. 1. Practicality - That is up to you as a creator, based on the situations and specifics you set up in your world 2. Cost-effective - In a large enough quantity, and given the resources you write into your world, this changes wildly. In the aforementioned Seveneves, they are in space and their first order of business is to attach a giant asteroid to the ISS land it on the moon, giving them as much metal as they need. However, this is something that makes sense given the setting, so you need to figure it out. 3. Combat-effective - Depends on the situations you write in. Even regular bullets aren't effective at all ranges: you want a handgun for at most 25 yards, a small rifle for 25 to 75 yards, various long rifles for from 75 yards to up to 2 miles, and something mounted to a ship or the ground for past that. You have to ask yourself these questions: When does the bullet start coming back? Is it after a certain amount of time? A certain distance? If it misses a pre-determined target?; Is the impact and penetration of the bullet lethal, or does using it as a bullet only serve to move whatever you actually want to hit the target?; What situations do these bullets get used in?; and finally, Which people use these bullets? It makes very little sense in modern terms for a tiny soldier to use a .50-cal as opposed to a M-16, and as such these are questions you should be answering. 4. Manufacturability - Again, all in your world. Since it's a space-fairing civilization, they have at least basic manufacturing skills (maybe, one could build rockets and spaceships via craftsman). It could also depend on how new this returning bullet technology is, since having a few made in a lab once is much more difficult than if they found a standardized assembly-line process. Deciding why you want to have these bullets h=may also help you find a solution. [Answer] It is not practical, you would need to launch the bullet/projectile with enough fuel to: 1. Stop its forward movement 2. Start movement in reverse 3. Slow down and stop when it got back. At each step it would need enough fuel/energy to carry the fuel/energy for the remaining steps. A person would not be able to handle the gun that held the bullet/projectile that would meet these requirements. In space there is no atmosphere to slow the bullet/projectile > > Newton's Three Laws of Motion > > > Newton's three laws of motion may be stated as follows: > > > * Every object in a state of uniform motion will remain in that state of motion unless an external force acts on it. > * Force equals mass times acceleration [ $ f(t)=m\,a(t)$ ]. > * For every action there is an equal and opposite reaction. > > > [Source](https://ccrma.stanford.edu/%7Ejos/pasp/Newton_s_Three_Laws_Motion.html) ## Edit/Maybe it could work? If it was a short range weapon, with a monofilament wire connecting the projectile to the weapon. Something like a high tech [paddle ball](https://en.wikipedia.org/wiki/Paddle_ball) and [railgun](https://en.wikipedia.org/wiki/Railgun) combination. The projectile is fired with electromagnetic force. The wire stops the projectile and starts it's return. The projectile is stopped in the barrel of the gun with electromagnetic force similar to its launch. You could rapid fire the same projectile multiple times per second. The only challenge is collecting enough [Unobtainium](https://en.wikipedia.org/wiki/Unobtainium) which is the only substance that that would stand up the strains for the wire and projectile, [Answer] It kind of sounds like you're possibly looking for something entirely different than what you might be first expecting: <https://en.wikipedia.org/wiki/Naval_ram> * Practicality? * Cost effective? * Combat effective? * Manufacturability? Practicality of weapons in space actually tends towards 'slightly questionable' in reality, but you have unlimited ammo for as long as you have fuel [and that you haven't rammed something bigger and badder than yourself...] with no risk of stray shots going where you don't want them, assuming you retain navigational control. As far as cost effectiveness goes, your "Ship as a bullet" means that you should be able to double up resource usage in its construction: As long as you're not getting flanked, your ram is pointed towards your enemy, and will double as added armour. Combat effectiveness will depend on your ship design and what kind of ships you're facing off against, but it holds the potential to be very effective. [And you could also design the 'space ram' as some manner of bolt-driver or power hammer, so that it launches forward just before collision - Reducing the effect of the impact on your ship, while maximizing the impact on the target.] Manufacturability, well, you're building heavily armoured ships anyway, and no longer need to worry about building guns or ammo to go on said ship... So I guess this might be a practical bonus? [Answer] This might be a stretch, but I think there's a way to do this and meet almost all of your points. ## Fire your bullets while in orbit at velocities that don't cause them to leave orbit This would require you to be orbiting a planet/star, but assuming your hypothetical space fighter was already orbiting a planet with the intent of defending it or attacking anything else also in orbit, and you've have a limited range of where you could fire and hope to see that ammunition again. If you can manage that, then any missed shots (that don't hit anything on their way around the planet) would end up back at a point that could easily be calculated upon firing. At that point, it's a matter of being in the right place at the right time, and being ready to catch a bullet effectively being fired right back at you. One problem with this approach is littering orbit with debris that's potentially much more dangerous than usual, so rounds that aren't caught or tracked instantly become a hazard to everyone in that bullet's path. [Answer] 1. These are explosive bullets: shells. They are fired towards their target and explode on impact or proximity. 2. If they do not encounter a target within a finite amount of time then they use their explosive as rocket fuel, slowing their forward momentum and setting the shell on a return course along the path it came at an orderly pace. 3. Returning shells can be collected, reloaded with explosive and used again. 4. This is worth the effort because these are really awesome, fancy shells and you hate to waste them. [Answer] If you want it to return without any effort on your part, that's not going to be cost-effective or bullet-sized. You are essentially building an self guided missile (that doesn't carry explosive payload) that rams then returns. There are two ways to make bullets less "wasteful": 1) What you could do is make it easier to RETRIEVE. You can make it with a special material that only responds to certain force (like certain metal with magnetism). That way, you can fire and then turn on your bullet-collection device and collect all the bullets. 2) Make bullets something you can salvage to create from the environment. You know how people fashion arrows from trees OR how slingshots can be used with random small rocks? Something like that, but more streamlined. Maybe some device that super-cools moisture in air into ice projectiles or a coilgun weapon that shoots any mass that can fit into your gun (so you can literally shoot tiny rocks). [Answer] Making a bullet return to the user would more than double the size of a bullet for it's lethality while increasing its complexity and cost WAY more than standard munitions because of the high-tech control devices required for such a projectile. So, it will basically fail all 4 of your goals. Since the cited question expressly shows concern for stray fire causing collateral damage, I think a frame challenge is in order to answer this underlying question of how to limit the range of bullets in space to prevent accidental shooting things in the distance. By firing explosive shells instead of solid slugs, your bullets could be given a fuse where by they would just blow up after N-seconds to prevent them from hitting something in the distant background. While the bullets will still have some debris, it will now be much smaller fragments similar to the micro-asteroids ships have to be designed to survive anyway. This answers your 4 requirements because explosive rounds are already a viable form of ammunition for mass production. All you need to do is add a simple fuse to existing designs similar to what you see in firecrackers or hand grenades. [Answer] Guns in space with bullets that return? 1. Practicality - Very impractical unless you can breed (research costs) these bullets to contain all the high quality components that are needed in a spaceship plus an explosive payload or the ability to hold a lot of kinetic energy. Plant based? Something robust that doesn't need a lot of care. Weedy growth? 2. Cost effective - See above. The main advantage of bullets is that they're cheap and disposable. Autonomously returning bullets goes against that. But if, like above, you can cheaply grow your returning bullets you're golden. 3. Combat effective - Greatly reduced against something else that spends 100% on its effective mass to be a dumb heavy bullet. Unless this is a bomb which has a lot more complicated guts. However if they function as more of an infection that turns your enemies into bullets then maybe it could be effective. But, again, we're moving away from classical bullet philosophy of "spray and pray" into a more complex paradigm. 4. Manufacturability - See above. You'll need to grow them. Maybe from crystals? Maybe from your enemies? Overall, no, whatever you do it's no longer a bullet. However, self returning munitions opens up a whole complicated nest of problems: Complexity vs Mass trade off. More complex means less reliable, but more functions. You can't get much simpler than a hunk of lead. You can't get more complex than an autonomous rocket ship. How do you stop them from killing you? They return, but how fast? What about when they miss? Or when your enemy is able to hack their navigational systems. Never forget "Using a weapon against your enemy is an invitation for them to do the same." So, if you come up with something to need to, simultaneously, come up with countermeasures. [Answer] The book, "We Are Legion (We Are Bob)" has an excellent example of this, although it relies on somewhat futuristic technology. He describes taking the same drive used for space travel (I think it was some kind of "gravitic drive" or other) and just sticking one into a remote-controlled steel sphere and using them like intelligent cannon balls. It gives him an edge against opponents who mostly are still stuck in the use-once exploding missile paradigm, especially since the protagonist decides he doesn't want his ship to be full of explosive materials for his own safety. [Answer] The projectiles could contain folded solar sail with solar cells and microchip - the controller. These would have to survive the firing intact, which isn't feasible especially in the case of railgun. If this is feasible regardless (I smell phlebotinum), then after "I haven't hit anything" timeout the controller would deploy the sail and steer the bullet by combination of sailing and orbital mechanics. The trajectory could be preprogrammed, but solar flares may blow it off-track. So maybe there needs to be some navigation equipment included, such as star tracker (a mini-telescope). With all this, we are speaking of multi-year delays, unless there's vast infrastructure to intercept the bullets nearby. [Answer] Boomerbullets are an insect-sized breed of animals from the iron core of Jupiter. They are used to high-heat and high-pressure, and practically indestructible compared to fleshy humans. They feed on heat and if removed from their home planet they will gladly migrate towards a source of heat, such as a gun. Once in the chamber they will eagerly wait to be fired and then gently return for another fix. [Answer] As you are advanced enough for space combat, i'll assume any guidance issues solved. This makes the answer about energy only. A bullet has kinetic energy mv2, and any retrieval will have to at least match that energy, plus a little extra for the return journey (which should be much slower for safety purposes). As retrieving the bullet implies that there is substantial mass (relative to firing) left, the (chemical) energy content should be much higher, otherwise the whole bullet is rocket fuel, expending itself on the return. Rocket fuel has energy on the order of (the equivalent of) an object travelling at a few thousand meters per second, which, sadly is probably below what you envision your bullets at. Some handwavy antimatter fuel could return bullets with original speeds way into the 100 000m/s area. ]
[Question] [ Assume that I have some way to introduce nutrients into the body of a healthy human but I do not have any method of changing their biology. No surgical procedures nor special "drugs" that would affect the normal functioning of a human body. Would any of the 2 following methods lead to a human not needing to "go number 2"? * Getting nutrients in fully liquid "soups". * Getting intravenous injections of some form of serum that contains all needed nutrients for the body to be healthy. If not is there a plausible way a human could achieve this? [Answer] The tricky problem is bile. If a person is fed and watered completely by vein (this is done routinely; total parenteral nutrition) the guts can atrophy but they still make mucus and bacteria still live in them. Even a person on TPN must poop occasionally. A person might have all of the intestines removed and have the stomach be a dead end - sometimes that can happen with an obstetric catastrophe or certain tumors. The remaining problem as regards excretion is then the liver. The liver makes bile as part of its job and it is not going to stop. That bile has to go somewhere or it builds up in the liver; you get jaundiced and then eventually die. If you do not have intestines and are living in TPN there must be some route established for the bile to drain. One way is to have a drain placed. Your OP precludes surgery of this sort and so as posed, the question is no. The guts are not going to completely quit making stuff while they are still alive. [Answer] The real question is, for how long? Short-term: Sure. A few days or even weeks is doable and shouldn't cause any lasting harm. Long-term: Only if you have to. There are consequences to your health. A friend of mine lived for years with nothing but a central line and drinking water. She had profound medical problems that caused her gut to shut down. She could not digest food and she got down to the 80-something pound range before her doctors finally took action. A [central line](https://www.cincinnatichildrens.org/health/c/going-home-central-line) is an IV. It's just like a regular intravenous line in your arm (or sometimes leg) except it's placed (usually) in the chest. A [PICC line](https://blausen.com/en-gb/video/cvc-and-picc/) is another possibility. It starts in the arm and is threaded further toward the chest. These types of IVs allow larger volume of materials through them. The downside is they're harder to put in and they run a high risk of infection. But they're pretty stable. My friend could tie off her tubing, cover the site well, and go out, even do sports (non-contact sports like kayaking). She was fed with all the macro and micro nutrients she needed. She drank water to provide additional fluids (and because it's really awful not to have any water as your mouth and throat get uncomfortably dry). Periodically, she had to take oral antibiotics to kill off bad bacteria growing in her gut. It is not healthy to go without oral food that long. She would follow the antibiotics with probiotics. She also had to eat small amounts now and again so her gut wouldn't completely shut down. Remember, your [gut is the main component of your immune system](https://www.hopkinsmedicine.org/research/advancements-in-research/fundamentals/in-depth/the-gut-where-bacteria-and-immune-system-meet). So, sure, you can live off of IV fluids but you need a functioning gut. [Answer] Yes. People can live without colon, or small intestine, or stomach (however, there is probably no case of anyone surviving without all of them). In those cases, digestive system gets a "shortcut", which results in more frequent and more liquid "#2". With fully liquid "soups", some material would still has to be excreted from the other end of the system. With IV injections, excretion is not necessary, so, your goal is achievable, at least in theory. However, there are 2 practical problems: * We can not just leave digestive system non-functioning and presume that it would not cause any trouble. Some maintenance (or surgical removal) of stomach and intestines would become necessary; * Long-term IV feeding is unsustainable at the current level of medical science - people develop problems with veins, infections and liver failures. ]
[Question] [ What would be a valid reason for human blood/sweat/body fluids being toxic/harmful/caustic to an alien species' skin? What would the aliens' organic biochemistry be like and what would their DNA be based on for this to occur in a plausible way? Any variable degree of reaction to the aliens' skin? [Answer] The first thing that came to my mind was iron. Human, and mammalian blood in general, 'captures' more oxygen than the normal oxidation process of iron. This process is complex, and requires many stages and components (enzymes, for instance). The blood system, and red blood cells (RBCs) in particular, have developed unique defensive mechanisms to preserve this functionality. > > Studies from our laboratory have shown that oxidative stress plays a > significant role in damaging the RBC membrane and impairing its > deformability. RBCs are continuously exposed to both endogenous and > exogenous sources of reactive oxygen species (ROS) like superoxide and > hydrogen peroxide (H2O2). The bulk of the ROS are neutralized by the > RBC antioxidant system consisting of both non-enzymatic and enzymatic > antioxidants including catalase, glutathione peroxidase and > peroxiredoxin-2. However, the autoxidation of hemoglobin (Hb) bound to > the membrane is relatively inaccessible to the predominantly cytosolic > RBC antioxidant system. This inaccessibility becomes more pronounced > under hypoxic conditions when Hb is partially oxygenated, resulting in > an increased rate of autoxidation and increased affinity for the RBC > membrane. > > > From [Red blood cell oxidative stress impairs oxygen delivery and induces red blood cell aging](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3937982/) for instance. So the alien species, having evolved an entirely different blood system, would have a completely different method to preserve tissue integrity. If, for instance, the alien method required ROS (from the quote) systems to function properly, our blood antioxidant defensive system is designed to naturally neutralize such systems. For instance, if their planet were not rich in iron, they may have used hydrogen peroxide as a transport method. [Hydrogen peroxide](https://en.wikipedia.org/wiki/Hydrogen_peroxide) is very reactive, and eagerly gives off the extra oxygen molecule to form water. Their 'hemoglobin' could conceivably have evolved into a method that binds an extra oxygen molecule to water in the 'lungs', and then releases it in the tissue. The very systems that our blood has evolved to protect the functionality of our blood hemoglobin system could be precisely the system that destroys their naturally evolved systems to protect their equivalent to our hemoglobin. Co-incidentally, this would make their blood just as 'toxic' to humans. It would be like pouring hydrogen peroxide on it. Note, hydrogen peroxide was once used as an antiseptic, until it was found that its oxidizing properties also destroys healthy cell tissue, and delays healing. [Why Does Hydrogen Peroxide Fizz On Cuts?](https://www.livescience.com/33061-why-does-hydrogen-peroxide-fizz-on-cuts.html) > > Despite its negative effect on healthy cells, our bodies' cells > naturally produce hydrogen peroxide when we metabolize food and turn > it into energy. So how can a cell produce something that can destroy > its own walls? That's where catalase steps in: when a cell creates > hydrogen peroxide, it stores it inside the cell's specialized > organelles, called peroxisomes, which contain hydrogen > peroxide-busting catalase. Inside of a peroxisome, hydrogen peroxide > decomposes and is turned into harmless water and oxygen gas . > > > This quote, incidentally, also posits a credible system for a hydrogen peroxide based blood oxygen delivery system, since the mechanism is already present in some form in earth-based mammals. Your question did not mention how fast you want the reaction to be. [Answer] The most unexotic answer would be that we are the peanuts to their allergy. Some little molecule from the plethora of substances in our blood triggers their immune response which then goes into a tailspin, sowing destruction on their tissues and organs. The molecule would need to be small to guarantee fast diffusion through the aliens' skin, and ubiquitous in humans - nucleotides come to mind. We would not even need to carry the actual allergen, we might just carry a protein that works as an enzyme on some molecule prevalent on the aliens' skin, breaking that down into an allergen. There are many ways to kill an organism - I propose you look at a suitable killer substance or mix (VX to humans, Roundup to green plants, Oxygen to anaerobic bacteria) and just decree that something in the humans' blood works on the aliens in an equivalent way. - Note that sometimes, as in the case of Roundup, a mixture of substances is needed, as the actual killer can not enter into the organism alone. ]
[Question] [ In an alternate version of our world, lycanthropes and vampires were introduced about 300 years ago and are coexisting with us. Unfortunately, they had to adapt to our cuisine and avoid certain ingredients altogether. * Vampires don't have much trouble eating meat, especially rare, and even fruit and vegetables to some extent. However, they react badly to vegetables similar to garlic, large amounts of salt, or edible wood-like substances such as cinnamon. They also need occasional human blood but that can be produced synthetically. Dishes such as black pudding are popular. * Werewolves often have adverse reactions to things wolves (and therefore dogs) find toxic, but are otherwise just more inclined to eat meat. * Both react badly to mandrakes and foods containing more than very trace amounts of silver. What would have to be omitted from a largely British/Northern European diet, such as chocolate, cinnamon and garlic, in order to cater to these individuals? [Answer] The descriptions of foods you mention above sound to me a lot like a Paleo diet. If nuts and seeds don't count as edible wood, then you wouldn't even have to modify the diet much at all; you may need to take out avocados and their oils for the lycanthrope, and (possibly) some of the very green and leafy vegetables with high mineral content (because of the possibility of silver) but most of it should be fine. For the sake of argument though, let's assume that we can modify the Paleo diet by taking out nuts and seeds, as well as getting rid of spinach and avocado to be sure. We'll call it Occult Paleo. Black pudding can be eaten under such a diet, excess meat doesn't seem to be a problem and most of the vegetables are going to be fine (sans spinach and avocado). You can't do chocolate under this diet which works for the lycanthropes, although to be sure cocoa should be avoided altogether. Bottom line is that Paleo is a good starting fit, with a few extra restrictions to cover off the foods that are bad for dogs especially. If nothing else, it's a food program that's already mostly understood by some restaurants and caterers, so modifying it for your vampires and werewolves wouldn't take as much effort as starting from scratch. [Answer] They would need to be forced to learn how to order "steak, blue or rare, no garnish". And how to cook. They don't need to adapt to anything. Just go there and ask for a "burger, hold the garlic". I'm looking right now at a take-away menu and there is disclaimer "If you have ANY allergy to ANY products used in our menu please let us know. We will prepare your dish in allergen free pots". I don't know how about your local shop but mine hasn't carried mandrake since 1450. So that is one problem less. But now we can call butcher that will deliver half of ox to your door in 30 minutes. No questions asked. Because why would you want to ask why somebody need half an ox? The main problem you would need to address is why they need human blood. Main difference in human vs. animal blood is protein pockets. But the proteins are transported in the blood, you don't need to consume it to be able to have your proteins. And if you answer would be along "because I says so" then you can go and just say that no one needs to change anything. Your vampires and lycanthropes just learn to read ingredients on the back of the chips. [Answer] I sincerely could not think of any food containing silver, so I had to Google it out. Turns out that [eating silver is a thing, especially in Southeast Asia](https://en.wikipedia.org/wiki/Vark): > > Vark, also called varak (also silver leaf, German paper), is super fine filigree foil sheet of pure metals, typically silver but sometimes gold, used to decorate South Asian sweets and food to make those look more appetising. The silver and gold are edible, though flavorless. (...) Estimated consumption of Vark is 275 tons (according to BWC-Beauty without cruelty data) annually (c. 2016). > > > However, it seems that not only werewolves and vampires would be badly affected by it (though regular humans could at least tolerate larger amounts of it): > > Concerns have been raised about the ethical acceptability and food safety of Vark, as not all of it is pure silver (sometimes aluminium is used, which is toxic), nor hygienically prepared. > > > --- Every responsible dog owner knows that there is one human food that is poisonous to the vast majority of dogs: chocolate. [Check this site for the reason, data, and a toxicity calculator](https://osf-global.zoom.us/j/5937554252). Supposing a werewolf weights at least as much as a human, they should be able to tolerate more chocolate than a dog, but they will still get intoxicated. Maybe the calculator helps you with ideas for how they would feel. The active component of chocolate that harms them is called [theobromine](https://en.wikipedia.org/wiki/Theobromine), by the way. Pet owners also know that caffeine is extremely dangerous to dogs, but it should not be so for werewolves. The reason is that the lethal dose of caffeine is about the same for dogs and humans: around 150mg per kilogram (about 2.2 pounds) of body weight. Pets usually suffer caffeine poisoning because they weight so much less than us. However, do notice that when caffeine is metabolized by a human, around 12% of it turns into theobromine (see the link I mentioned before), so I would expect a werewolf to at least suffer a little from a few cups of coffee. Finally, most dogs hate citrus/citronella. Many dogs don't, though. I believe it's due to their sense of smell being so much more sensitive than ours. I would expect werewolves to avoid it like we humans avoid rotten food. --- So, long story short: food products containing theobromine should be labeled so in order to protect werewolves, and both werewolves and vampires should avoid vark. [Answer] A dog/wolf's poisoning due to consuming chocolate is called [Theobromine poisoning](https://en.wikipedia.org/wiki/Theobromine_poisoning) and is due to more than just chocolate. The linked article lists a few other foods. > > Theobromine poisoning, also wrongly called chocolate poisoning, is an overdosage reaction to the xanthine alkaloid theobromine, found in chocolate, tea, cola beverages, açaí berries, and some other foods. > > > I would recommend you read the article. It's fairly short and has some good discussion about toxicity levels based on the animal's weight, etc. You might have some lyncanthropes in your world that eat chocolate or drink soda in spite of the risks and are only moderately affected based on their level of consumption and regularity. Maybe a parallel to humans drinking alcohol despite the negative short-term and long-term affects. [Answer] Wolfie could eat chocolate. Chocolate is toxic to dogs because they don't have a developed liver (so they can't process chocolate), in the case of werewolfs, I´ve always thought that the inner-organs structure stays the same therefore there wouldn't be any problem with them eating chocolate. I think that growing extra hair, long nails, etc... makes sense, but having the liver dissapear or become rudimentary at their transformation it's a little bit dumb. Unless your werewolfs are like those in Twilight that LITERALLY transform into enlarged wolves I see no problem having a "classic" werewolf eating chocolate. Sources I recently watched a video about homemade moonshine repercutions on a human body which touched on how the liver processes certain toxins and makes them non toxic for us, and they gave the example of dogs and chocolate. <https://www.youtube.com/watch?v=4DQUrg0Yhu4> Also, in many websites that give their approach to lycanthropes biology, they don't mention any kind of transformation realted to the liver. Idk It would be cool to research that, Who knows? maybe you end up debunking the taboo of werewolfs and chocolate. Side Note This isn't related to the question but I found it interesting to mention. If your characters adapted to human society ¿What about substitutes? You know like all of those vegan/vegetarian meat-like food ¿Wouldn't it be good for the enterprises on your universe to create a garlic-flavour for those edgy vampires who love the taste of it or an edible chocolate for werewolfs? P.S. Sorry for my bad english, I'm not a native speaker. ]
[Question] [ At the minimum, I'd like to create a creature with a jaw structure that splits into 4 moving parts (like a +-shape or an x-shape). In order to keep food in, the cross sections will have stretchy flaps of webbing attaching them. A requirement for the 'mandibles'/jaw-sections is that they can move independently of one another, with beak like dexterity. One earth creature that has a jaw analogous to what I'm trying to capture is a python. Their lower jaws are not rigidly attached to the skull, the lower jaw is split (but still held together by a stretchy ligament), and the jaw sections can move independently in order to 'shimmy'/push prey into their esophagus. [![snake jaw](https://i.stack.imgur.com/sAPBl.jpg)](https://i.stack.imgur.com/sAPBl.jpg) (source: [purch.com](https://img.purch.com/h/1000/aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzA0Ny84NjQvb3JpZ2luYWwvMDcwMTA1X3NuYWtlX2phd3NfMDIuanBn)) The creature I'm designing would be blind, and since it is alien, the brain does not have to be housed in the 'head'. The creature will look a lot like an ant eater, and it swallows it's food whole. I'm just not sure what the skull would look like. The best I can imagine is the mouth is not actually attached to a real skull, rather it's like a shark in that the jaw is isolated from the brain case. ![shark jaw] (<https://c8.alamy.com/comp/F649YD/shark-skeleton-oxford-university-museum-of-natural-history-F649YD.jpg>) [Answer] # Split the Maxilla and Mandible Morphing earth-based, amphibian-descended creatures to have four jaws isn't too difficult. All the required bones are already there; it's just a matter of getting the muscles and bone shapes right. There are valid concerns with this approach since having four "fingers" attached to your face greatly reduces the strength of your bite compared to two thicker "plates". # Bones Earth based animals almost always have a [maxilla](https://en.wikipedia.org/wiki/Maxilla) (upper jaw bone) and a [mandible](https://en.wikipedia.org/wiki/Mandible). Two bones make up the maxilla and two bones make up the mandible. If we separate the mandible and maxilla both into two pieces, that would give us the four moving parts requested. The maxilla and mandible already have teeth embedded in them so you'd just need to change the shape and count of the teeth to match your alien's needs. [![inferior view of maxilla](https://i.stack.imgur.com/p3lDv.jpg)](https://i.stack.imgur.com/p3lDv.jpg) # Muscles Each new limb of the jaw will require minimum four muscles to control it. Two to open and close, two to move side to side. If there's articulation in the jaws then more muscles will be needed (think of how many muscles are required to move human fingers). # Configuration You'll need to be careful with how the jaws open and close. You'll also need to pick a hunting method (ambush or pursuit). Relatively long jaws like this emphasize speed of closure over absolute strength. # Conclusion Yep, you can totally do it. You'll just need to be careful about the prey you choose to hunt. If the prey is too big or tenacious then your jaws will break and the creature starves. Remember that evolution morphs what it has into new shapes or removes existing structures. It's relatively rare to get entirely new structures (bones, organs, etc) in a creature. [Answer] ### Pharyngeal jaws might be a solution Moray eels use them since the normal fish suction method does not work in a burrow. The inner jaws can actually reach out and pull something down the throat, that way they can eat things that are too large to swallow normally. [![Sketch of the oral jaw and the pharyngeal jaw of a moray eel](https://i.stack.imgur.com/rrRKf.jpg)](https://i.stack.imgur.com/rrRKf.jpg) [source](https://en.wikipedia.org/wiki/Pharyngeal_jaw) [Answer] At this rate why does it even need to be a bone jaw. Why not make it like an octopus / Cthullu with tentacles feeding a food hole. The evolutional advantage of a functional jaw is a structure capable of processing large hard food chunks into smaller bits more easily process able by the bodies digestive system. the two part jaw is physically efficient at this because its a lever/vice capable of exerting large amounts of energy on a small surface area. So more jaw parts actually results in a weaker bite. So if you make the jaw more about fitting or stuffing stuff into the mouth you can have as many sections as you want, ignoring the bite of course. [Answer] The human premaxillary bone is fused to our maxilla. But fish have split premaxilliary bones. Many lines of fish use the premaxillary bones to protrude the mouth, swinging them down and laterally. [![fish anatomy diagram](https://i.stack.imgur.com/uWafI.jpg)](https://i.stack.imgur.com/uWafI.jpg) <http://blog.hmns.org/wp-content/uploads/2010/05/archy-teleost-puckerBlckF.jpg> These premaxillary bones are hinged at the midline. Here is another image to show how these structures can support the edges of the mouth to maximize gape. [![fish diagram](https://i.stack.imgur.com/gFinf.jpg)](https://i.stack.imgur.com/gFinf.jpg) <http://slideplayer.com/slide/3468357/> That will do for the upper "jaw" as regards opening wide. It is interesting to me that as far as I can tell, the lower jaw is solid. Even fish that want a big gape like bass or tarpon do not so it by splitting the mandible. Maybe they need a firm anchor. I cannot think of any reason why your creature could not have a split premaxilla and then split the mandible too. I think the main reason for such a big gape is that they can suddenly do it and suck in prey. I was not able to find a good skeleton of a paddlefish or other big filter feeder to see the skeletal underpinnings of their fixed gape. Fish have two sets of tooth bearing structures too - oral and pharyngeal jaws. [Answer] With the shark picture you use, I'm surprised you didn't come up with the [goblin shark](https://en.wikipedia.org/wiki/Goblin_shark), next to the moray eels (and Ridley Scott's Alien) the best known "extendible-jaws" creature. That's "goblin", not "gobbeling" shark as my kid says quite topically. As an aside, the remark about a "bobbit" (polychaete worm Eunice aphroditois) is off; it uses bristles like others use pincers. I'm attributing its mention to its appearance in Blue Planet II recently, where I was puzzled by Attenborough using its 'popular' name that refers to a 1990s incident/meme! ]
[Question] [ In this world, magic exists. The technological level is medieval, but weapons like magically reloading crossbows exist. Magic has the following rules: 1. All magic requires runes and a verbal activation (saying 'magic words' that correspond to the runes). Runes are one-use only. 2. Any spell lasts a maximum of one minute (no enchanting) 3. Any spell has a certain maximum amount of power, and will not complete tasks under that power (you can create a small fireball, but can't make a storm or teleport) 4. Any spell takes three seconds to take effect after the verbal component has been said (gives time for a counter-spell) 5. Runes can be traced on a surface (traced rune) and can then be activated only by the maker, or engraved/written (engraved rune) where they can be triggered by anyone holding the object. 6. All activation phrases must be yelled, and cannot be muffled (can't use magic while gagged or holding cloth over face) So the question is: Why have the humanoid denizens of this world not developed magical firearms? [Answer] Because medieval metallurgy stinks. While decent steel was available, it was extremely expensive. Decent, relatively inexpensive steel only appears in Europe around the late 1500 to early 1600s which is well into the Renaissance era. One of the oft overlooked aspects of making a firearm, or almost any tool and weapon, is metallurgy. Making a chamber able to withstand the enormous pressures of an explosion in a very small space, plus the barrel to withstand all those hot gases, is remarkably difficult. [Black powder](https://en.wikipedia.org/wiki/Gunpowder) is relatively low pressure compared to [smokeless powder](https://en.wikipedia.org/wiki/Smokeless_powder), and the pressure wave was relatively slow. This required a long barrel to get the most velocity out of it. The low pressure meant your firing chamber could be relatively weak compared to what is needed with smokeless powder. So late medieval metallurgy was able to deal with black powder muskets and cannon. Firearms, really [hand cannons](https://en.wikipedia.org/wiki/Hand_cannon), first appear in China around the 13th century and show up in Europe and Arabian hands in the 14th. Around mid 15th century, the [arquebus](https://en.wikipedia.org/wiki/Arquebus) shows up, the first thing you'd recognize as a musket. This places only the most basic hand-held firearms solidly in the [late medieval period](https://en.wikipedia.org/wiki/Late_Middle_Ages). That's what your society would be capable of. Regardless of whether it's black powder or a tiny magical fireball, it's the same pressure for the chamber to withstand. And it's the same lead ball going down the same inaccurate smooth barrel. So they'll have the same limitations. Nobody's going to have a Glock, magic or no magic, with medieval metallurgy. You get the equivalent of an early black powder musket, at best. --- That said, there are reasons why you'd make a magical musket. Most of the innovations in muskets were to speed loading, and make the trigger more reliable. Magic can help. 1. No powder to carry around and keep dry, just carry the shot. 2. No powder residue to foul the inside of the chamber and barrel, a serious problem with black powder. 3. Loading would be a bit faster, no powder to pour and pack in. 4. No trigger mechanism to reset. 5. No expensive and unreliable springs. 6. No lit match. No flint to keep spaced just right. No touch hole. Not having to deal with powder nor a trigger mechanism would be of great importance to a late medieval musketeer. Powder has to be carried, measured, and kept dry. Powder residue quickly builds up in the barrel and chamber requiring cleaning. The black powder residue could build up so fast in the barrel you'd literally have to use smaller balls if you didn't get a break to clean your gun in battle. Trigger mechanisms will be the bane of firearms until percussion caps in the 19th century. The first would be a matchlock, literally carrying a slow burning rope to touch off the gunpowder. Then wheellock, using a spring to turn a wheel against a flint to throw sparks onto the gunpowder... hopefully. But wheellocks were very expensive, springs are expensive with medieval metallurgy. Finally the [flintlock](https://en.wikipedia.org/wiki/Flintlock), a piece of flint striking steel, became the norm in the mid 17th century, but the matchlock stuck around. It's not until the mid 1800s that we finally get the cheap, reliable [percussion cap](https://en.wikipedia.org/wiki/Percussion_cap) primers that we know of today: a small explosive that reliably detonates with a very hard whack. If you told a medieval musketeer they could have a musket which required no powder, no match, no flint, and no trigger, they'd jump at it. [Answer] Because 4. That's so much time compared to a bow, it's not feasible. A magic wand unleashing the wrath of gods and killing half an army (or at least a few guys), sure, but a magic 9mm projectile that goes off three seconds after shouting hey you there watch out 3 ... 2 ... 1 ... heck, I'm pretty sure even I'd have a good chance of dodging that after a little timing training. Plus it gives so much time to just pull my bow and shoot that guy pointing his gun at me ... --- For big battles those disadvantages might be small compared to having easy to use weapons with good range and penetration, however the reason muskets were invented before rocket launchers is physics. Magic has other boundaries. Something way more destructive is possible. Why fire only one bullet if you can fit 100 into a box, aim at the general direction of the enemy forces and magically release all off them at once? Depending on the exact specification of the magic there is always a way to design a more powerful weapon, unless all the magic can do is imitate a little explosion like used in a musket. [Answer] Because nobody had a reason to invent them. When searching for more and more effective ways to kill someone at a distance we (in our non-magical state) found that certain combinations of barrel, gunpowder and slug could be very lethal where mechanical weapons had pretty much reached the limits of their effectiveness. But the development of the firearms took a lot of time, metallurgical skill (as Schwern's excellent answer pointed out) and a concerted effort on the behalf of those people who wanted to kill other people at range better. Now consider your system. Why would you possibly want to invest time, energy and money into creating a tube that fires an inaccurate ball of lead an indeterminate distance when you can instead slap a rune of target finding onto your arrow? Why waste effort creating a weapon that needs a three seconds to fire when instead you can have a three second magical reload and be confident of actually shooting your target? Why bother making a gun that can pierce armoured foes when instead you can buy, ready made and compatible with your favourite crossbow, a Bolt of Burrowing (now with 110% more agony)? Depending upon how long magical effects can last and what you're allowing in your magical system you can even pre-activate certain runes to avoid the lead time on the spell and the chance of a counter. If I nock an arrow with a pre-carved 'explode on contact' rune (naturally being careful not to let the tip of the arrows touch anything once armed) then I effectively become the magical equivalent of a mortar. A full group of archers with such weapons could be far more effective at area denial than even the best group of magi-musketeers. Naturally the effectiveness of such an approach is limited by how long magical effects like this last once activated, but as long as arm to fire time is shorter than the magical dissipation time (or a person holding a weapon can re-activate runes as much as they like), an archer with a pre-nocked arrow can be far more effective than a gunman with the flint ready to fire. Not only that, but if you consider the difference in size between a lead ball and an arrow shaft you have much more room to be inventive with. A medieval war arrow has plenty of shaft on which to write destructive or guiding runes. A lead ball? Not so much. Basically what I'm saying is that in your world there is far more incentive to use magic inventively to make existing ranged weapons more deadly than there is to invent a whole new system of weaponry. The limits of effectiveness for the humble crossbow are the limits of your magic system itself, so nobody actually needs to try make a better ranged weapon (except by trying more and more potent magics). Those who do try to make magical firearms quickly find there is more damage to be done (and hence profit to be made) from carefully crafted weapon runes. [Answer] I have wrestled with this specific problem myself (as is likely a common theme for this category). I am still working on the story, so I won't divulge too much of my solution, but here is the basic idea to use as a working example. > > The world upon which the story takes place is unique. It exists in a null space of sorts leftover from an ancient race with the power to create and destroy worlds, stars, etc. The 'null space' is a bit like an old and forgotten janitor's closet, but an entity from that era yet remains in the form of a 'dark star' which is thought to be a sentry of sorts for the strange discontinuity in space. It is purported by some to be the cause for the incomprehensble source for the failure of most sorts of complex technology on the planet's surface. While many sorts of simple technology is unhindered, most more complicated items (such as guns) simply will not work. One theory goes as far to claim the strange opaque stellar phenomenon is able to alter reality, effectively changing the rules of physics and chemistry within the dominion of the null region. Evidence of technological failures may be found in the excavated remains of interstellar vehicles which helplessly fell victim to the planet's gravity well after losing all propulsion and systems upon approaching the lone planet.... > > > Of course, the reason for the need of such a thing is to magnify the use and importance of Rhunic incantation, or magic. ]
[Question] [ I have a situation where a large oil field is discovered in a country ruled by a junta with abysmal human rights records. On the one hand world oil prices are very high, which puts pressure on governments, and on the other hand there's strong moral pressure to boycott human rights abusers. Trading with the junta would be a huge PR nightmare and be seen as rewarding a criminal regime. Is there a way for (some) countries to buy oil from them? Maybe through some countries that don't care much about human rights, or by turning a blind eye to oil smuggling. Overthrowing the junta is NOT an option. [Answer] Consider these examples: 1. Saudi Arabia. 2. The so-called Islamic State. 3. Venezuela. All of these governmental entities (because Daesh isn't recognised by any nation) are rated by Amnesty International to have abysmal human rights records. Amnesty International says that in [Saudi Arabia](https://www.amnesty.org/en/countries/middle-east-and-north-africa/saudi-arabia/), there were over 150 executions, summary judgements are routinely issued, thousands of people have been expelled from the country to dangerous areas, there is government discrimination against Shia muslims, and there are severe restrictions on basic freedoms. The West still buys oil from them. The so-called Islamic State is famous for its violations of human rights. But until recently, with the advance of the Iraqi army and more effective coalition airstrikes, Daesh was earning millions of dollars a day in smuggling oil at below-market-prices, selling it to tankers which would then cross the border into Turkey. So oil was and still is being bought from them. [Venezuela](https://www.amnesty.org/en/countries/americas/venezuela/) has also committed some human rights violations as well, imprisoning journalists which have spoken up against the regime, killing political opponents, etc. Until very recently, with the near collapse of their oil infrastructure, the West bought huge amounts of oil from them as well. In general, people are willing to overlook human rights abuses if a country is willing to provide a cheap and dependable supply of a vital natural resource. Countries need petrol to fuel their cars, ships, military, etc. Democracies face electoral unrest if oil prices rise too high (even though it is preposterous to blame a national government for the movement of the global petrol market). Unfortunately, the human rights of people far away don't really matter that much when countries don't need to see or hear of them. [Answer] Just don't buy directly from Junta. Their oil will be trading at a discount because demand is restricted. A third party registered in PR friendly country will come in and buy and sell. You just need plausible deniability you were not aware the third party was sourcing from Junta. Even if you don't know and it is later discovered you may have a PR problem because you should have know. Embargo and PR are not the same. If your county has an embargo then you may be in criminal violation by bypassing the embargo. Crude oil can be traced to the field so you are going to have a problem there. The incoming port can just sample the oil. But I don't think the refined gasoline could be traced. [Answer] You could always buy it in secret and alter any document which has its origin. Embargos only apply to the country or countries that issued it, so Another option is to get another country to purchase it, and sell it in to you. [Answer] Do like ISIS currently does. They smuggle out oil into surrounding countries. Those countries buy it at extreme discount then resell it. A really ambitious plan would involve an underground pipeline. [Answer] IRL the axe on this trade was [Marc Rich](https://en.wikipedia.org/wiki/Marc_Rich#Early_life.2C_marriage_and_career). He basically developed the spot market for oil, and then used it to circumvent oil embargos in the 70s and 80s. Commodities traders like Glencore are necessary intermediaries to make this happen. You can get more detail on Marc Rich's shady dealings in ["Metal Men" by Craig Copetas](http://kadamaee.ir/payesh/books-tank/02/Copetas%20-%20Metal%20Men;%20Marc%20Rich%20and%20the%20$10%20Billion%20Scam%20(1985).pdf), a pretty tasty muck-raking book from the 80s. A better reference, informed by interviews with Marc Rich himself, is "The King of Oil" by Daniel Ammann (available on Amazon). ]
[Question] [ In a world I've been creating, space and time are mutable. Not in the traditional sense, but because non-sentient magic crystals warp space and time as their means of reproduction. Now, this warping can't affect sentient creatures or their artifice, allowing people to exist for more than 15 minutes without being wiped, and this is all well and good. By actual issue is that the crystals make monsters in the space they shape. All the time. They're always making new breeds. And this is also fine, but it leaves a dilemma. How can I justify any given type of creature being created more than once? There's no guiding intelligence behind this system of constant re-creation, and I'd rather not say "Because reasons." As an added detail, anything created does have to abide by the laws of physics, though given the presence of magic these are obviously a bit more pliable than our own. Basically, no generation of Cthulu's daydreams. [Answer] What you're asking for are meta-principles, or meta-laws, and those are fun. For an imaginary world you can specify whatever you like - as long as you abide by them. If you don't like the results, you can (as one strategy) produce an opposing set of principles, and have the two sets of principles locked in eternal conflict. But here's a possibility: Rupert Sheldrake's "morphic resonance". The existence of forms predisposes other forms to follow in the same pattern. If you posit the equivalence of "morphic noise", then new creatures will be approximately like the parents, but not necessarily exactly. Small differences, such as color, might be common, but the greater the deviation from existing forms the lower the probability of it occurring. Or try this: the language of the crystals limits the results of their creation, as a sort of magical proof of the Shapir-Whorf Hypothesis. And by language I don't mean a spoken (or even conceptualized) language, since the crystals are not sapient. It is common in literature to speak of "the language of rocks" or "the language of trees", so I'm more thinking of the patterns of behavior and underlying forces which cause the crystals to produce new creatures. This is, of course, pretty non-sensical from a materialistic viewpoint, but once you get into the realm of magic all that pettifoggery ceases to matter. [Answer] It seems obvious, at least to me: when the same thing (your crystal) performs the same action, the result will be the same. Some minor variations in it's ambience result in minor variations of the same theme. Thus, only a greater change in the environment leads to a different type of monsters. It might also be that not every monster created in this way can survive, much like only some combinations in for example mammalian genome result in a living organism, while others simply are not viable, which, in your case, would result in no monster being created (or, if you prefer: only a damp spot) [Answer] Patterns, a specific pattern might work well and be used again by the same crystals, and as it reproduces, it's 'offspring' might keep some of the patterns, maybe altering them a little. So the same kinds of creatures would tend to pop up in the same places. [Answer] If the crystals warp space as a means of reproduction, then the way they warp space is subject to evolutionary pressures. Assuming that offspring crystals may exhibit slight changes in their composition or behavior from their parents, then if a specific pattern of creation or procedure is more likely to allow offspring crystals to form, that pattern could end up favoured by the offspring. You can take this further by having different "breeds" of crystals, each of which has its own "preferences" for the kinds of stuff it makes. Some players may be skilled in identifying these breeds, since predicting the behaviour of crystals seems like an important survival skill in this world. [Answer] If this was a programming question i'd say "use a pseudorandom number generator". This is something which looks unstructured and random to the viewer but actually uses a fixed sequence of seeds to create the "randomness". Think of a world in Minecraft, which consists of millions of cubic kilometers of random-seeming terrain, all of which is totally reproducable from the world's seed value, which is just a short alphanumeric string. This could be the key to reproduceability in your world: whatever is driving the crystals could be effectively using a list of "seeds", allowing the same creatures to recur. Perhaps the seeds are some natural feature of the higher-dimensional space which the crystals inhabit for example. Maybe there is some element of "evolution" in the choice of seeds used. [Answer] Consider Conway's Game of Life starting on a random configuration. A number of static and dynamic patterns will result. Likewise, if seething sea of quantum fluctuations at the planck level gave rise to random quarks, these would generally form into protons, electrons, etc. In both cases there are random elements which still must adhere to a set of rules, and can exhibit complex phenomena (but not all imaginable phenomena). [Answer] Patterns repeat all the time in nature, e.g. the moon continues to maintain the same orbit around the Earth and we continually see the same cycle of New-moon - Crescent - Half-moon - Full-moon regularly, and also causes the tides to come in and out with the same period every time, even though there is no sentience involved. There's no reason why, depending on the nature of the warping, the crystals don't keep passing each other at the same vectors every time (as they are each moving on their own repeating pattern which is dictated by something akin to an orbit or something), and therefore create the same shaped monsters. [Answer] They have some random system that given some time will create a monster. If we assume that the system is truly random, it will start at a random state, its state will evolve randomly over time, and then at some random time it will pop out a monster. In such a system a high likelihood of the monsters being of specific type corresponds to the states corresponding to such type being more stable, so that the system spends more time in such states. Such states are called [attractors](https://en.wikipedia.org/wiki/Attractor). All it really means that if you are at or near such a state then random fluctuations towards that state are more likely than fluctuations away from the state. This arises naturally whenever the random fluctuations are bound by some relation to the current state of the system. This is almost always the case to some degree. In your case we actually know this to be the case. A truly random system would be exceedingly unlikely to generate viable monsters, but we know the random fluctuations of the system often do generate monsters anyway. This implies the systems has strong attractors that correspond to viable monsters. This requires the system actually is the type to have attractors. While deliberate design could produce a system that uses attractors at one level but true randomness at another, this is extremely unlikely to happen naturally. Thus it is entirely natural to assume that some types of monsters are much more likely than others because the attractors corresponding to them are stronger. Sorry for the unclear explanation, but the short version is that if we assume a natural system that creates viable monsters as a side effect then having some monster types be highly likely is actually the probable outcome. [Answer] I think the simplest way to address this problem is to attribute each instance of warping to the interactions of a finite number of crystals. This way only finitely many types of warping can occur. If each type of warping creates a specific type of monster, then there must be repetition amongst the monsters created. For example, suppose that the crystals are randomly distributed throughout space. Further suppose that warping will occur whenever between $n$ and $m$ crystals interact. This can create $m - n + 1$ different types of warping resulting in $m - n + 1$ different types of monster. Because this process is repeating and $m-n+1$ is finite, at least one type of monster must also be repeatedly created. ]
[Question] [ This question already has answers here: [Explaining Archaic weapons in a high tech world](/questions/48254/explaining-archaic-weapons-in-a-high-tech-world) (6 answers) Closed 1 year ago. First, a quick explanation of the world's functioning. 1. It was home to nature-worshipping tribes, which had such a strong connection to the goddesses that developed to be like super-humans (longevity, bigger stamina, keen sense of strategy...), but also otherworldly skills (manipulation of fire and water, healing,...). However, after the arrival of foreign civilizations, many fell ill and those who remained were victims of genocide. 2. The story will take place 400 years after first contact, when the main character, who is a warrior discovers that the fae people are still alive and that, in fact, it is against them that they have been fighting for centuries. 3. The existent technology supports the existence of television and the internet, but I would like to keep body combat and the use of weapons like swords, knives, harpoons, bows and arrows as the main ones (other than guns for example), but I don't know if there's any way to make them justifiable in a context of war. Can anyone help me? Thank you in advance! [Answer] ## Guns don‚Äôt work in the fae kingdom. No modern technology works in fae kingdoms, as a matter of fact. JK Rowling used this idea in Harry Potter: although TVs and telephones and PlayStations exists, the strong magic around Hogwarts prevents it from working there. So your fae can use guns etc when they are on human territory. But surrounded by their own, the supernatural powers of the fae prevent modern technology from working. Hence, swords and other ancient weapons are their primary method of war. [Answer] The fae cannot perceive technology. The fae are old. Also pretty weird. They have stone age technology; bows and spears. They do not use modern technology. Because they cannot perceive modern technology. They can't watch TV. They do not perceive guns, or cars, or phones. Bullets and cars pass through them. The converse is also true. There are things in the fae world that moderns cannot perceive and by which moderns are unaffected. The world of the fae and the world of technologic moderns do not overlap completely. This is part of how fae persisted all this time. This is also part of what brought about their ruin in the past age. Tech using moderns shoot each other with guns and zip around in cars and planes all the time. But if a modern wants to fight a thousand year old fae, the modern will need a fae weapon or one made in a similar way. -- I am reminded of the naked nature spirit from this answer: [Why would nature spirits be naked?](https://worldbuilding.stackexchange.com/questions/118295/why-would-nature-spirits-be-naked/118341#118341) [Answer] So there's two universes that immediately sprang to mind: Dune and Warhammer 40K Both have Ranged combat, both however have a significant focus on Melee: In the case of Dune, it's because of (according to Lore) the interaction between a Laser weapon and a personal shield creates an explosion that can vary from individual scale all the way up to the size of Atomic Weapons. Since everyone uses personal shields, no one uses Lasers in combat as it could trigger total annihilation. Depending on what the Fae have, a similar limitation might be applicable (Magical sheilds that reflect/deflect the energy of a ranged weapon which could cause collateral damage) 40K has several reasons for Melee combat: 1: To please the Gods of Chaos (Blood for the Blood God! Skulls for the Skull throne!) - The chaos god of Khorne (think the manifestation of Humanities innate desire to kill each other) strongly favors Melee combat, believing it to be more skill based and thus 'honorable' (despite being a Chaos God, Khorne is strongly aligned with Honor, so things like 1v1 duels earn his favor). Linking back to your world, the Fae may likewise have a similar honor system - such as it being bad to kill an enemy without being able to look them in the eye or that to kill someone leaving them alone to take their last breath is seen as cruel/evil or that to kill someone without giving them a fair chance to escape or retaliate is shameful. Depending on your real world inspirations - some of the Native American honor code(s) around combat may be applicable. 2: Ranged weapons need Ammunition, A Sword never needs to be reloaded. In 40K this is often justified by a few genetically enhanced super-soldiers (The Space Marines!) facing down against hordes of enemies (Filthy Xenos!) and so a ranged weapon would so quickly run out of ammunition making it pointless. In your story, it's the few against the Many - so it's possibly they might opt for a Melee focus since they couldn't possibly carry enough Ammunition. 3: Different worlds have different Tech levels - in 40K some worlds are at a feudal level, others are hyper advanced. In the real world - we have the Amish and the Luddites - those who actively reject technology due to a particular belief - it's entirely possible your Fae feel the same way. 4: Melee doesn't have to be weaker than Ranged. 40K is infamous for it's ludicrously overpowered weaponary, such as the Chainsword, Lightning Claws, Thunder Hammers Monomolecular blades etc. There is no reason why you cannot make your Melee weapons imbued with some reason why they are intrinsically better - a Sword might be able to be enchanted or otherwise enhanced by a physical connection with the being that wields it, something that a Projectile cannot maintain once it leaves the barrel - thus making a flaming sword bolstered by the Users otherworldly skills that requires it to be held in order to work is plausible. Putting aside some of my favourite universes: There's no reason why a planet that supports the Internet and TV would have to have the natural minerals to make gunpowder. It could be that atmospheric conditions (too much oxygen, not enough oxygen, significantly higher atmospheric pressure) provide a limitation that makes Firearms impractical. It could be that the report of a Firearm being discharged draws some dangerous predator to the location making use of Firearms extremely hazardous and only a last-resort option. [Answer] # Magical trees provide all You've already established that a godddess provides supernatural abilities. She also gives trees supernatural abilities. All of the weapons come from varying trees, and are vastly more powerful than any tech they can make. A bow made from a goddess touched tree will fire an arrow faster, harder, and more accurately than a gun. A sharpened branch can block bullets and rip through metal armor like paper. Guns require too many small parts, and destroy the magic of the trees. # Show guns failing at some point Have guns be a minor plot element at some point, and have them just be nakedly inferior to bows and swords, and the wielders get destroyed. This shows your civilization is smart to avoid them. [Answer] I challenge your question. --- ## You don't have to justify anything. [Destiny's world](https://en.wikipedia.org/wiki/Destiny_(video_game_series)) is similar to our own, plus space magic. People use the usual - shotguns, auto rifles, etc - plus some technomagical stuff, like pew-pew blasters and laser beams. But they also use bows and swords. Sometimes shields and warhammers, even. Or a pointy stick with a built-in laser blaster on it. Because why not? It may not always make sense. Why using a big sword when you can go pew-pew on your enemy? Why pulling a bow to snipe someone far away when a sniper rifle would do a better job, theoretically? Nobody cares. It's just awesome, and that's good enough. So, go a similar route - make using swords or bows or whatever weapon you want awesome, by means of tech or magic, and you're set. Those weapons look cool. It's fine to use them, as long as you do your own twist to make them awesome. If Lucas was able to pull it off the way he did on Star Wars, everyone else also has the right to their wild, strange, fantasy weapons with an archaic flavor, too. Just make sure to add some spice to them, and you're set. [Answer] You can't enchant bullets. These "otherworldly skills"? They've proven quite useful and humans have learned to cast them on weapons. However, for some reason or other (materials necessary, incompatibility with supersonic speeds, etc.) you can't put them on bullets, so people tend to fight with enhanced melee weapons and arrows instead. [Answer] Lasers (with visible light wavelengths) are... visible. Guns and cannons (gunpowdery stuff throwing projectiles) are loud. Bows and arrows, and knives (and others) are both invisible and silent (at the time of using them). So they reveal neither the location of the attacker, nor the attack itself. That's why they are always valuable in under-cover operations. ]
[Question] [ An environmental phenomenon, cloud or mist of sorts, rolls into an area that greatly affects "thinking machines". Basically, any types of computers or logic instrument based on electrical impulse/inputs are severely degraded in their performance or outright stop working while under the duration of this phenomenon. While most machines regain their ability to reliably work again after some repair, without adequate protection such machines are simply are irreparable or so damaged that they're written off. Low level electrical devices are fine for the most part. Sure, the light bulbs might flicker a bit, but it's not like they shut off completely or explode. What type of weather phenomenon (natural or manmade and fictional obviously) would cause technology that computes using electricity to become defective while under the duration of said phenomenon? But also leaves low-level electrical systems intact? Basically, computers may not work the best, but lightbulbs still do. Edit: Defective in this case means that a computer doesn't have to outright break with sparks coming out of it or anything like that. It could be as simple as that the machine is giving wrong outputs or wrong calculations (see the issues of bitflips for example). Essentially this would make computers unreliable. Similarly, repair doesn't necessitate going in with a hammer or wrench. It could be as simple as a hardware or software reset. Furthermore, any society living through such conditions wouldn't use integrated chips for their lower-level electrical applications like lightbulbs. So, it can be safely assumed that the lower level electrical devices would be fine. Even if they're considered outdated by our standards. The main thing affected here are computers. [Answer] You have a problem, let's call it problem #4, but we'll discuss that in a later. First, let's discuss what you mean by "low level" electrical applications Ignoring the issue I'll bring up momentarily, a "low level" electrical application differs from a "thinking machine" application from a physics standpoint in only two ways: 1. "Low level" electrical applications have long wires. 2. "Thinking machines" depend heavily (but less every day) on magnetism. When you hear threatening terms like "Electromagnetic Pulse" (EMP) and the usually Hollywoodesque consequence that everything electrical dies, what you're really hearing about is a powerful enough electromagnetic signal (no different from radio other than the amplitude is overwhelming) that those long wires (like your house wires) suddenly start acting like antennae and channel all that energy into unprotected circuits. Lights, cheap electronics like your clock radio (stuff that's slowly going out of style...) are all examples of unprotected circuits. Your lights are especially a good example. Most of the time they're not a grounded circuit other than to ensure the fixture never energizes if there's a short. I've actually lived through this kind of an event. A lightning strike occurred close enough to my house to fry phone and electrical wires inside the wall. It coupled energy on the Centex-style parallel cable between my computer and printer. It didn't hurt the protected computer, but it fried the data input board on the printer. Phones died. Lights died. I'm glad to have not suffered worse because my house could have burned down. In a similar manner, a strong magnetic pulse can damage computer circuitry. More specifically, it can damage memory. Hard drives, some on-board memory types, etc. (Stuff that's slowly going out of style.) A big enough pulse, such as one that can be created with a nuclear explosion, can scramble magnetism-dependent circuitry. To my knowledge, there's not a way to naturally generate a magnetic pulse without the electrical component. But what's the opposite? I want to damage just the "thinking machines." Let's assume you're looking to damage the machines and not simply wipe the memories clean. In that case, we're dealing with short wire antennae. *Really short wire antennae.* As in you're trying to couple energy onto the traces between the major components inside the computer chips. Or at least the data busses inside those chips (the longest wires short of the power and ground planes, which aren't really "wires"). This means the wavelength or frequency of the electromagnetic pulse is important. Simplifying things a bit, the length of an antenna is 1/4 the wavelength it's expected to deal with. A 100 Khz radio station is broadcasting on a wavelength that's 3km long. The ideal 1/4 wavelength antenna length is therefore 750 meters long. We don't have the time to go into antenna physics here. Suffice it to say that you can use harmonic fractions of the ideal 1/4 wavelength... but now you know why old style AM radio with short antenna had a really limited range or they had a honking tall antenna. We're talking about picking up a wavelength that's 4X the length of the average bus wire in an integrated circuit. That might - maybe - be as long as 2mm. That's a frequency of 150Ghz. That's in the microwave frequencies. * And that brings us to problem #1: an EMP capable of coupling energy onto the bus lines of integrated circuits would cook every animal within its range. Including humans. It would vaporize water and shatter trees because of it. There's a price to be paid to do what you're trying to do. Why don't cell phones cook our brains? Well... Ignoring certain realities[[1](https://healthtalk.unchealthcare.org/the-effects-of-smartphone-usage-on-the-brain/)][[2](https://www.verywellmind.com/how-do-smartphones-affect-the-brain-2794892)][[3](https://neurosciencenews.com/cellphone-radiation-brain-cancer-18889/)], the amplitude of the signals isn't anywhere near what's needed to heat water, which is how microwave ovens cook. Let's ignore all this for now. However, if you did this, your lights would flicker but not be affected. The frequency is too high to efficiently couple energy onto lines as long as your house wires or the cross-country power lines. * Problem #2: Well, maybe... The physics of coupling energy get a bit funny when you're trying to affect something really small (I have two words for you, just two words: impedance matching). Let's just sweep this under the rug. When I mentioned cellphones, you might have thought, "if Ghz transmissions are dangerous to computers, why doesn't my cellphone burn itself up?" Remember earlier when I mentioned protected and unprotected circuits? The amplitude of cellphone signals aren't high enough to get past protected circuits. * Problem #3: You have a real problem here. My computer wasn't damaged directly by the lightning strike because the frequency of the EMP was way too low (we'll ignore the fried surge protector that, had it not been in place, would have damaged the computer's power supply. But that's not damaging the computer per se.) Here's your problem: every pin on every critical integrated circuit is protected with what's called ESD Circuitry. "ESD" means "Electrostatic discharge." Up until now, ESD meant things like picking up the chip without first grounding yourself. You know those little electrical sparks you used to annoy your younger siblings? That kind of thing wreaks royal havoc with electronic circuits. That's ESD — and every pin has circuitry to protect the inner circuits from it. Problem #3 is that a Ghz-level EMP looks an awful lot like ESD. Now, that could work in your favor from a suspension-of-disbelief perspective by suggesting a great enough amplitude that the ESD circuity burned out, effectively disconnecting the pins from the internal circuitry. Of course everyone's BBQ, but let's ignore all of this, too. OK... so what's the real problem? Bring on Problem #4 already! * Problem #4: Everything's a "thinking machine" today. You're 30 years out of date in the way you're thinking. LED lights have control circuitry that's nothing more than simple integrated circuits. Any natural EMP that could hurt a computer would hurt the computer in your LED lights. And your cell phone. And your car. And your washing machine. And your refrigerator. Problem #4 if that you're too late. Even if we come up with a believable natural event that could damage short-wire computers and not long-wire house circuitry, all that long-wire house circuitry powers short-wire computers. Many electric razors have integrated circuits inside them. Everything would burn up. Instant 1968. But you won't mind because you're BBQ anyway. But let's ignore all that. What natural phenomena could produce a 150Ghz pulse with enough amplitude to couple energy onto a significant number of computer chips, frying them like so much dough in hot oil? To be honest, I don't know of one. Even a nuclear blast is slow compared to what you need. I'm sure I don't have a complete meteorological knowledge to judge what conditions could exist, but everything else I can think of (electrically charging the atmosphere, raising the ground plane voltage in the soil, solar emissions of any kind...) simply can't produce the nasty mess you need to ~~cook humans~~ damage computers. A fast enough lightning strike could do it, but (a) it must strike someplace where the energy can dissipate really quickly, like the middle of a lake where there aren't any computers to blow and (b) lightning has a very limited range. A bolt with enough energy to affect a really wide area would require a lake of exactly the right salinity and purity to dissipate the energy while it's vaporizing. Water really isn't a great conductor. Gratefully, you're using the [science-fiction](/questions/tagged/science-fiction "show questions tagged 'science-fiction'") tag At the low end of suspension-of-disbelief is the idea of a super-lightning storm that produces strikes that achieve what you need. Middle-of-the-road suspension-of-disbelief would be a condition that causes very powerful [ball lightning](https://en.wikipedia.org/wiki/Ball_lightning) using something along the lines of the proposed [Microwave cavity hypothesis](https://en.wikipedia.org/wiki/Ball_lightning#Microwave_cavity_hypothesis). This could conceivably produce a magnetic pulse (vs. an EMP). Remember, magnetic memory is disappearing. You'll probably see that in your lifetime. And the result would only be scrambled memory, not damaged computers. But, hey... it's something. Also in the middle are solar events like flares or mass ejections. This stuff wreaks havoc with satellites, but very rarely affects the Earth. When it does, it tends to affect long power lines (antennae...) and not computers. But SciFi has been blaming solar flares for everything for a long time, so your readers won't notice. At the high end of suspension-of-disbelief is an atmospheric meteor strike that produces an EMP equivalent to an atmospheric nuclear blast but for whatever reason (maybe it's not dense enough), it doesn't hit the ground causing an extinction-level event. [Answer] ### Bit-flips induced by radiation storm A computer works by loading an instruction from its working memory (you know it as RAM), doing whatever that instruction says, and repeating that cycle several billion times per second. Instructions are very basic things like "add these numbers". Only after obeying some billions of instructions choreographed by computer engineers do we get pretty cat pictures displayed on our screen. How do the instructions get into working memory? Other instructions put them there! Except for the first few instructions, which are hard-wired. When your PC or cellphone starts up, it loads its own instructions from the hard disk, and stores them into its working memory, so it can follow them later. (At least, that's the essence of what it's doing) That means after the computer has started up, it's running on "circular logic". Everything relies on that working memory being intact, and should that memory somehow get corrupted (i.e. not contain the instructions it's supposed to) it has no reliable way to fix itself because the instructions to detect the corruption and fix it would also be stored in the working memory. At the same time, working memory is usually a technology called DRAM, which is physically quite delicate. Bits are stored using small electric charges. The more bits the designers fit into the same space, the smaller each bit is, and the smaller charge is used to store it. If the electric charge is disrupted, a 1 can be "flipped" to a 0 or vice versa. [Radiation from cosmic rays](https://en.wikipedia.org/wiki/Single-event_upset) can induce or disrupt small electric charges. It's [been shown](https://en.wikipedia.org/wiki/Row_hammer) that even accessing from the same part of it over and over very quickly. (In fact, charge even leaks away naturally. So every few milliseconds the memory system checks the charge level of every bit, and resets it to a full charge or no charge.) So, your environmental phenomenon can be a radiation storm. Make up a new kind of radiation that strongly affects silicon, but not DNA. When a few bits get flipped, it can randomly crash programs, crash the entire computer, corrupt data, or have no effect at all. If it's happening a lot, though, it's guaranteed to crash the entire computer sooner or later. Your phenomenon is quite strong and flips bits all over the place. --- Many devices like microwave ovens also run on little computers, called microcontrollers. These use a different memory type called SRAM, which is pretty robust against radiation. The bits are also much bigger, since these are optimized for low-cost manufacturing instead of fitting lots of memory in a small space - it doesn't take much to run a microwave. Microcontrollers often have the ability to detect crashes and reboot automatically. are often able to reboot automatically after crashing, which takes some milliseconds (not seconds or minutes like a PC). The instructions for a microcontroller are stored in a separate program memory, which is usually flash memory. Although flash memory uses electric charge, just like DRAM, it's done in a different way which requires huge electric forces to flip bits. On the other hand, it doesn't self-correct every few milliseconds, so cumulative exposure to radiation may still flip them, causing the device to malfunction. Assuming the chip isn't actually damaged, this can be repaired by re-programming it, by someone with specialized hardware and a copy of the correct program. --- Although LED lightbulbs use microchips, they use much simpler microchips which are hard-wired for one purpose only - to convert electricity from one form to another. Often these chips don't have any working memory at all. Sometimes the chip does contain a few SRAM bits for various purposes - like remembering which part of a cycle it is doing. If your radiation does manage to flip one, it will cause some little hiccup or glitch rather than a complete system "crash". Wi-Fi lightbulbs are an exception, since they are based on microcontrollers. [Answer] Solar wind-like radiation Space probes we send have [specially designed protections and fault recovery circuits](https://www.nasa.gov/feature/how-nasa-prepares-spacecraft-for-the-harsh-radiation-of-space/) because the radiation in space affects their circuits. Earth is protected by this radiation because of its Ozone layer. So, if you have local holes in it, the radiation will pass through and can fry electronics circuits! Some will say that this will also affect vegetal/animal life, and thus we will be fried. But they also forget that even without the Ozone layer, there is still the atmosphere. We are safe! and all electronic circuits are cooked to your taste :-) EDIT : Apparently the real radiation is enough to affect circuits without affecting life, so I removed the section about having to handwave some details of it. [Answer] Your run of the mill RF jamming should do the trick. I'll focus here on jamming usb cables and WiFi network. This fits into your definition of computers not working (since computer without keyboard is not much of a computer), but your toilet can still flush water since its microcontroller is alive. From personal experience: I had 50W RF transmitter (probably at 14Mhz or 21Mhz) just below my computer monitor and next to USB keyboard. It had coaxial cable running across the room and outside of the window. When it was transmitting USB keyboard would start sending junk to my computer. I could fire up notepad and see random key presses incoming. And that was all not even from antenna, it was leakage through the coaxial cable. (Take that all EE teachers who claim coax don't leak!) On bright side, RF frequency is not ionizing and shouldn't cause (a lot of) cancer. And powers might be low enough not to cook people alive. On not so bright side, it would take about 1 hour for someone to ask question on stack overflow on how to protect against this weird weather and get told to start using ferrites and shorten the cables and build house from reinforced concrete. If for whatever reason you want to cause even more damage, next easiest thing to attack would be Wi-Fi. I tried jamming my cell phone by placing it right next to a Wi-Fi router, but it totally did not care, so we know that 100mW is not enough to jam. I have no idea how much power you'd need to apply there. Aliexpress claims 1W can jam the room. If they are correct, that should be low enough not to cook humans alive. Problem here is that defense against this is also pretty simple. You either move to 5Ghz wifi, or you use your cellular phone, so it is one trick pony. Unfortunately, I can't think of any natural phenomena which would cause such amount of interference over long time (as opposed to EMP which just burns devices instantly). If you want to go deep into science fiction, plopping a nuclear reactor on a plane, attaching it giant amplifier and flying it over whoever you want to jam might work. Some back of the napkin math: Free space path loss at distance of 1km is 57dB @ 24Mhz and 97db @ 2.4Ghz. If you want to induce 100mW to device you are jamming you should need 100KW transmitter @ 24Mhz (for usb jamming) and 1GW @ 2.4Ghz for Wi-Fi Jamming. If you want to be safe, maybe bump these numbers 1000x more to compensate for those pesky reinforced concrete walls. [Answer] From all the answers given so far, it's clear that a type of radiation (unless you go completely hand-waving) is difficult to use unless you want to fry humans too. DNA is not more resistant than memory... Then, issue #4 from @JBH answer is a real problem, but it could be maybe the solution at least for the next 10 years. You can use a super computer virus. It acts at a very low level, to some characteristics that all the modern CPUs have (like the speculative execution thing...), but it's fast to propagate, very fast, and it basically stops or even fry every CPU on the planet. In milliseconds. Simpler things haven't got modern/complex CPUs yet. Or have they? [Answer] Are "thinking machines" necessarily silicon-based electronics like we have today? With the surging popularity of machine learning, some tech companies are building custom chips optimized for the types of computation needed to simulate a neural network. Today, these are still silicon ICs with zillions of transistors. But perhaps somebody will invent a neural network computer that uses a different underlying technology, and that's the part that's corruptible by an environmental factor. For example, maybe they find a way to manufacture actual biological neural networks (which are more efficient because they directly model the solution rather than simulate it). Maybe those are only used in larger more demanding scenarios because they're not cost effective for small scale devices. A manufactured biological net might be susceptible to microbes or enzymes that break down essential neuro transmitters. ]
[Question] [ I am working on a small worldbuilding project. The world this takes place in is littered with 5,000 year old (estimate) ruins, and these ruins are full of decaying radioactive material. In most locations, it's not too much. At most, 50-150 mSv an hour. Not good for one's health, but not so deadly as to prevent Ruin Haunters from scouring the region. In some pockets however, one can reach 5,000 to 6,000 mSv an hour. Haunters have made the connection between lead and stopping these 'cursed spirits' from being able to corrupt them, and some have come up with the idea of lead plate or scale armor to fend off these 'cursed spirits.' The Haunters have access to manufacturing technologies up until 1900, a significant improvement to the 15th century world that existed not even a century prior. Haunters work in crews of 4-6 and stay within ruins for two weeks on average. Is this armor feasible? For more context, see [Radiation poisoning and primitive peoples](https://worldbuilding.stackexchange.com/questions/223155/radiation-poisoning-and-primitive-peoples). [EDIT 2/2/22] All the answers I have received have been very helpful in their own ways. I find it difficult to select a single answer as most helpful - and so I shall select none. Thank you for responding, you have all been most beneficent. [Answer] # Not a lot. Yet a lot. After quickly reading some articles I found that they use lead aprons to protect themselves during things like x-ray and such. They are about 7 to 14 kg (10-20 pounds), so not very heavy. This isn't much radiation compared to what you're asking. Though. I would go much stronger. Another article stated that radiation can be reduced with 95 to 98% with 2,8 to 18mm (0,71 inch) thick lead sheets. This in some ways isn't much and would reduce the 5000-6000 mSv to 250-300 mSv. Still not healthy, but a great deal better! The weight? A quick back of the envelope calculation says it's 19 to 504kg (42 to 1111 pounds) for the lower bound, 38 to 1008kg (84 to 2222 pounds) for the upper bounds. That is because the aprons generally have 0,25mm thick lead shields, while you require 11 to 72 times as much. Aprons are often single sided as you know where the radiation is coming from. This is likely too high. I've added the full weight of the apron, but there's probably some weight not belonging to the lead in the apron. Let's be extremely generous and say it's 10%. That's still very roughly 17-900kg (38 to 2000 pounds). Mind you, this is for either only front or both side aprons. An armour requiring to only protect the vitals (torso, neck, head, genitals) would in most cases be too heavy to carry. Ranging from difficult to impossible. That would still leave many sensitive areas like some bone marrow open. [Answer] Lets have a quick think about what sort of radioactive materials are likely to be long enough lived (given the 5000 year delay since the end of their production you mentioned in the older question) and produce gamma rays. Assuming that controlled nuclear fission is the main source of the [radioactives](https://en.wikipedia.org/wiki/Long-lived_fission_product) involved here, you'd expect to have things like 126Sn, 93Zr and 129I. These are beta-emitters, but their decay products are 126Sb, 93Nb and 129Xe, respectively, sometimes in an [excited state](https://en.wikipedia.org/wiki/Nuclear_isomer). These decay by various means, the excited states release 40.4keV, 30.8keV and 39.6keV gamma rays respectively and these are the probably the main sources of gamma radiation that you'll be dealing with. NIST has helpfully compiled a list of [x-ray mass attenuation coefficients](https://www.nist.gov/pml/x-ray-mass-attenuation-coefficients) for us with a wide range of photon energies and materials. For simplicity, lets assume we're only dealing with 40keV photons. This gives us a [mass attenuation coefficient](https://en.wikipedia.org/wiki/Mass_attenuation_coefficient) $\mu$ of 14.36cm2/g for lead, 3.629cm2/g for iron and 5.685cm2/g for aluminium (which is difficult to produce, but may be straightfoward to scavenge, post-apocalypse). In order to reduce incoming radiation to 1% of its initial flux, you need a layer of material with density $\rho$, thickness $\ell$ and mass attenuation coefficient $\mu$: $0.01 = e^{-\mu \rho\ell}$. The thickness will therefore be $\ell = {\log(0.01) \over - \mu \rho}$. For lead, this would be .28mm, for iron 1.6mm and for aluminium 3mm. I'm not quite sure how much material you'd need to make an all-enclosing radiation-onesie, but lets say it is 3m2. That gives your 99% shielding a weight of 9.6kg for lead, 38kg for iron or 24kg for aluminium. A double thickness shield would reduce radiation to 0.01% of its initial flux, and would weigh twice as much. Obviously lead, if you can find it, is the ideal material to use here. Other scavengable materials can also work though they'll be much heavier... but note that a 1.6mm onesie made from iron is a reasonable suit of armor and a useful thing to have if you're expecting to get into a fight and haven't re-invented firearms yet. --- However. As L.Dutch pointed out (and I implied in my last answer though admittedly didn't make it explicit) the bigger risk is in inhaled and ingested radioactives. That long-lived waste decays via beta-emission, and whilst beta particles generally aren't excessively dangerous on the outside they are pretty bad news on the inside. Modelling risks of radiation exposure is hard, so I don't think I'm going to try that right now. But I have a sneaking suspicion that the background level of gamma radiation might not actually be that bad, and as long as you're not trying to spend long periods of time in the hot zone you might not have to worry about it very much. But what you very much definitely should not do is drink the water, forage or hunt. You need a decent fabric dust mask (you could describe this as a kind of veil, if you were superstitiously inclined!) and if you do get dusty and dirty whilst you're in the bad lands then you should make sure to wash it all downstream of your village, and ideally before taking off your mask. Post expedition ritual cleansing (scrub all that contaminated mud out from under your fingernails!) is likely to be more beneficial than a lead foil onesie. [Answer] A lead armor will work only for protecting the body from radiation coming from the outside (and will be quite cumbersome to wear, but one can't be picky here). An alternative to lead, or an integration, can be represented by water cushions, which would be more flexible and could also be used as drinking water on the way back. For radiation coming from inside the body, an armor will do nothing. And in a highly radioactive environment, one needs just to breathe some dust to let radioactivity past the lead armor and directly into the body, where it will irradiate at libitum. [Answer] Lead. Bah. You want to look like a pipe? They will probably call you "The Pipe". They already do? Hmmm. In any case when am exploring the glowing ruins I will be wearing GOLD! [![GOLD ARMOR](https://i.stack.imgur.com/IyYtlm.jpg)](https://i.stack.imgur.com/IyYtlm.jpg) [source](https://hcabarbieri.it/2021/09/14/lil-nas-xs-gold-armor-unveiling-at-met-gala-channels-lady-gaga/) Gold is denser than lead (19 vs 11 mg/cc) so provides better radiation protection. Gold is much stronger with a tensile strength an order of magnitude greater than lead. And gold looks awesome! --- For this question I think "gold plate mail!" is enough. Because there will be no end to complaints about making real armor, armor that is good for fighting, making lead aprons, making alloys, no radiation after 5000 years etc etc. I am ok with an image of scale mail constructed using gold Krugerrands. [Answer] Yes, it is feasible. Personal protective devices include lead aprons, thyroid shields, lead glasses, caps, and gloves. Lead Aprons An apron with 0.5 mm thickness can attenuate approximately 90% or more of the scatter radiation. A standard lead apron weighs approximately 7 kg, which could cause the development of back problems. Lead glasses The lens of the eye is the most radiation-sensitive part of the body, therefore, wearing lead glasses is essential. Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. George Ravenscroft (1618–1681) was the first to produce clear lead crystal glassware on an industrial scale. Lead glasses with 0.5 or 0.75 mm thickness can reduce more than 95% of scatter radiation. Thyroid shields The thyroid gland should be protected because it is vulnerable to scatter radiation. The annual maximum permissible dose recommended to the thyroid is 300 mSv. A thyroid shield can reduce the effective dose by 2.5 times and the total exposure by almost 50%. Therefore, thyroid shields should have at least 0.5 mm lead equivalent thickness for neck and thyroid protection. [Answer] Another possibility here if the hunters are organized and working on a large scale: Instead of trying to wear armor they make a series of armor plates which are positioned to protect a safe path. Note, also, that they should know about concrete. To protect areas that are going to be accessed many times (say, the approach to the ruins) make some concrete walls. ]
[Question] [ I'm working on a project, a world filled with radiated ruins thousands of years old. People still search these ruins as even now they may hold valuable treasures. Many of these 'Ruin Haunters' come back with what we would recognize as radiation poisoning. How would pre-modern people view this? Many of this world's religions at least recognize the ruins, either as a place of great evil or as remnants of a world ruled by godly men. I'm sure the radiation would still persist at least a little after 5,000 years. Those who caused it didn't fear radiation. [Answer] > > I'm sure the radiation would still persist at least a little after 5,000 years > > > Though you haven't specified the nature of the radioisotopes, lets have a quick look at real-world [nuclear waste](https://en.wikipedia.org/wiki/Radioactive_waste). Short and medium-lived radioisotopes will be mostly gone by 5000 years... Samarium-151 has a [half-life](https://en.wikipedia.org/wiki/Half-life) of 85 years, for example, and after 58 half-lives there's going to be precious little of it left. Long-lived isotopes will be the only things remaining. Technetium-99, for example, has a half-life of over 200000 years and so at ~98% of the original waste will still be present. (note, don't confuse it with Tc-99m which has a much shorter half-life) On the flip side, long-lived radioisotopes are long lived precisely because they aren't super radioactive. You won't get the classic glowing green gloop or barren wastelands (unless the site was already a barren wasteland independent of the material stores there, I guess). There won't be any of the classic signs of radiation poisoning visible at all, I suspect, but more pernicious chronic illnesses that don't show up for a few months or years, or maybe not until you have children. If humans live there, they probably have moved in comparatively recently as historically it would have been a hazardous place to live with high rates of birth defects and cancer and so on. [Folk memory](https://en.wikipedia.org/wiki/Folk_memory) might have preserved knowledge of the history of the people who tried to live there, even if it didn't remember the origin of the site. After 5000 years though, it might just be "less healthy" than uncontaminated landscapes, and it might potentially even be less dangerous than other kinds of toxic industrial waste that don't decay over time. Nonetheless, people who live there, or drink the water, or breath the dust, might well be marked with shorter lifespans due to elevated cancer risks and deaths due to leukemia or lung cancers will be quite graphic to observers (for want of a better term). Older animals there might have tumors visible when butchered. Bad ground, tainted ground, evil ground... all sorts of superstitions. If illness is associated with artifact hunting then the artifacts themselves might be treated with great suspicion... if the "curse" laid upon the ancient tombs of our forebears takes years to strike down those who defile those tombs, who is going to dare keep looted goods in their homes? That's quite a gamble for anyone to take! [Answer] Evil spirits Anything causing bad effects had been attributed to evil spirits. The evil spirits, genies, witches live there and they don't want to be disturbed. Anyone who disturbs them bears the consequences. Forbidden areas by gods gods don't want anyone to go to the forbidden areas and whoever goes there gets sick. Cursed areas Those areas are cursed by magic spells and anyone who goes there gets cursed. [Answer] There's a real example of this. Australian aboriginies in the Northern Territory call the area with uranium deposits "sickness country". They have demarcated it quite accurately hundreds of years ago (at least), and have creation myths to explain it. The following is from <https://www.artistwd.com/joyzine/australia/abr_culture/sickness_country.php> , but there are many others of interest on google. Bula (The Creator) and Bolung (The Rainbow Serpent) Our land was first created by Bula, who came from saltwater country to the north. With his two wives, the Ngallenjilenji, he hunted across the land and in doing so transformed the landscape through his actions. In a number of places, Bula left his image as paintings in rock shelters. Bula finally went under the ground at a number of locations north of Katherine in an area known to us as “Sickness Country”. It is called this because the area is very dangerous, and should not be disturbed for fear that earthquakes and fire will destroy the world… Bolung the Rainbow Serpent inhabits the deep green pools found in the Second Gorge. We do not fish in the pools where Bolung sits. When fishing close to these pools, we can take only a small portion of the fish caught and throw back the rest in order to appease Bolung. Drinking water must not be taken from these deep pools but rather from the shallow associated waters. Pregnant women and new initiates may not swim in the Katherine River for fear of disturbing Bolung, who must not be spoken to and must be left undisturbed. [Answer] If some of the world's religions recognize the place as one of great evil, that's a pretty obvious explanation for why people who spend time there are afflicted with a mysterious disease. In response to whether it's realistic to have a place be radioactive after 5000 years, I have a suggestion. On Earth, there is a natural nuclear reactor that was created long before humans even existed. It operated for several hundred thousand years, so your world could easily have one that is still active. [This article from Scientific American](https://blogs.scientificamerican.com/guest-blog/natures-nuclear-reactors-the-2-billion-year-old-natural-fission-reactors-in-gabon-western-africa/) has a lot of the technical details, while [this Reddit thread](https://www.reddit.com/r/todayilearned/comments/erb0zv/til_there_was_a_natural_nuclear_reactor_in/ff31egj/) explains what someone there would have experienced. Essentially, the groundwater would periodically get very hot and emit enough radiation to cause cancer and mutations in plants, animals, and people. It's super cool, right?! [Answer] As the Starfish's answer tells you, after 5,000 you might expect rather limited chronic effects in those who frequent the sites, not acute radiation poisoning of those who go there once. These might surface after a number of years or in new generations. You'll have to decide how much knowledge survives intact. Without surviving knowledge people will have hard time even making the connection. Compare what we have observed with a primitive people affected by a [disease with a long-enough incubation period](https://en.wikipedia.org/wiki/Kuru_(disease)). ]
[Question] [ My story is set in an apocalyptic Earth (occurring during the story), and the main character is stationed out alone on a sea fort in the middle of the ocean. He receives a radio call/signal from a stranger on his radio (or something similar). I don't know enough about radio waves to know if this is plausible - could an SOS call show up on a radio like this? It's basically a voice in the wilderness - someone sending a one-way message out, hoping someone will receive it. Further, is there a plausible way by which he might 'fix' the device he uses so that he could be able to send a signal out back to the recipient, but that doing so would then permanently prevent him from receiving a signal again? I'm open to new technology (or old rediscovered tech) being used, as well as interference/jamming being caused by the environmental effects of the fall of civilisation around him. Thanks so much - the downside of my only studying arts/humanities is a real lacuna in my knowledge of science and physics! EDIT: So, a crucial plot point is that the main character essentially sacrifices his ability to receive transmissions in order to attempt to find a way to transmit back to the broadcaster. It's essentially an act of love and sacrifice, whereby he gives up the consolation and hope that receiving the messages gives him, in order to instead gives those things to the woman whose voice he hears. Therefore, it's crucial that a) the 'fix' to his radio means it can't receive messages anymore and b) the fix could conceivably allow him to transmit long-term. It wouldn't be worth it if he could only send one message, as with the battery/satellite phone idea below. [Answer] So, the crucial point, as I understand it, is that the hero must knowingly destroy his receiver capability in the act of transmission. Two-way radios actually have to put a fair amount of effort into not having the transmit and receive sides blow each other up. This is typically done by disconnecting the receiver from the antenna while transmitting. It's plausible that this component of the hero's radio has broken, and therefore if he attempts to transmit (by overriding the interlocks), he will destroy the low-noise amplifiers at the front end of his receiver. This has the benefit of allowing your hero to already possess a radio capable of transmit/receive, while explaining his reluctance to use the transmit features. It seems to fit the storyline much better than a failed repair job, as it is intentional rather than accidental. Also, I would hope that it would be understandable to a non-technical reader that shoving several kilowatts of power into just about anything that isn't designed for it isn't going to end well. [Answer] This is my time to shine (I'm a [ham radio](https://en.wikipedia.org/wiki/Amateur_radio) enthusiast). Ok, let’s break down the question: > > He receives a radio call/signal from a stranger on his radio (or something similar). I don't know enough about radio waves to know if this is plausible - could an SOS call show up on a radio like this? > > > Ok, so he gets a signal, and the message is not important, but before I get into the complex stuff: By all means, yes, this is very plausible. You want him to receive a signal, but he is not yet be able to reply. So here's what I think could happen: 1. he is stranded with a basic AM/FM/weather radio 2. he modifies it so that it can receive other frequencies 3. he is scanning and picks up a transmission > > Further, is there a plausible way by which he might 'fix' the device he uses so that he could be able to send a signal out back to the recipient, but that doing so would then permanently prevent him from receiving a signal again? > > > 4. here is where it could split into two paths 1. when he was modifying it, he gave it the ability to transmit, but it's not strong enough 2. he has to modify it so that it can transmit 5. then the story progresses and he is now in contact with whoever it was You could make it so the modification needs a part that he also needs for receiving and once he changes it, he won't be able to put it back or he accidentally breaks something and can no longer receive anything. So for not being able to receive, the first path wouldn't work because how could he know if it wasn't strong enough and how would he have received the message, so you would need to use the second path? This may not, however, be the most plausible solution, because he might not have the required parts or expertise to pull it off, so some hand waving might be necessary if you choose that. But this is not the only way; most other users have also had great suggestions, and it's a matter of what you think fits the story best. To help you decide, I've added a list of the other answers and some other possibilities too. * modifying standard radio (this answer) * It's a satellite phone that's low on battery by John Dvorak ([here](https://worldbuilding.stackexchange.com/a/174575/73498)) * Drone boat by Willk ([here](https://worldbuilding.stackexchange.com/a/174587/73498)) * Patricia Shanahan's answer ([here](https://worldbuilding.stackexchange.com/a/174581/73498)) * fixes old broken radio * I will update this list when i think of more PS: Welcome to Worldbuilding SE! [Answer] Drone boat. > > It's basically a voice in the wilderness - someone sending a one-way > message out, hoping someone will receive it. > > > A drone boat runs aground on his island. He wakes up and sees it there. This would be exciting too. He is not sure if anyone is on it. As it turns out there is a cat on it who is very happy to see him. There is also a message in an envelope taped to the inside of the windscreen. The message has coordinates. The drone boat is like a message in a bottle. --- Your sea fort has flying drones and drone boats. Or did have drones; they all got used during the apocalypse. But there are spare parts for drones, and the tech to steer them. Your character is handy with this sort of thing and has built some silly stuff just to pass the lonely hours. Now he has the cat to help him. He fixes the drone boat, charges up its battery and installs a spare, and sets the boat to travel autonomously to the GPS coordinates in the message. He also loads up some supplies requested in the message, and he tapes his own one-way message on the inside of the windshield. The cat does not want to go back on the boat, so your character sends a robot frog he built. [Answer] It's a satellite phone that's low on battery Far from any man-made destruction, immune to every disease known and unknown, designed to draw endless power from its environment, and always falling but never hitting the ground, these chunks of metal in the sky are here to stay, at least for a decade or so. Unfortunately for your hero, his last solar charger that still has a USB 4.5 port available, has just bitten the dust - and it's impossible to fix with the technology they have. They can convert it to a DA port ([double alligator](https://en.wikipedia.org/wiki/Crocodile_clip)) solar charger, but the darn phone refuses to charge through a DA port - at any appreciable speed, at least... or if you wish, the hero doesn't even need to tinker with the battery, but they do have only enough battery for one message, and then the phone turns off for good, or at least until a charger is found. Your hero can disable the battery's undervoltage protection to squeeze out enough juice for one more outgoing message, but the battery will be unable to charge after that juice is squeezed out. Li-Ion batteries have the unfortunate tendency to violently combust if operated outside of standard conditions, which include stuff like giving it too much power, taking away too much power and then giving it some, giving it power too quickly, taking away power too quickly... [Video of a battery exploding due to a short circuit](https://www.youtube.com/watch?v=HCGtRgBUHX8) And sure enough, it's just at this moment that the phone makes a loud ding, and sure enough, it's one of those cases that require a response. It's up to you to decide if it's a [cell broadcast](https://en.wikipedia.org/wiki/Cell_Broadcast) style message, something akin to the amber alert thingie, if your hero is subscribed to a message board (it was a miracle to find one that still works) or if the hero's phone line is one of official public utility, one of his many, many tasks being to provide a rescue service in the general area. Alternatively, it's not the electric charge your hero is low on, but credit. Perhaps it was originally sponsored by the government but there's nobody anymore to pay the bills and the AIs left to run it now do not care about emergency. [Satellite phones](https://en.wikipedia.org/wiki/Satellite_phone) are very much a thing even today, and even today one of their benefits is that they continue to work after a natural disaster, as well as that their coverage includes such remote areas as a sea fort in the middle of an ocean. And even today, satellite phone services include those that can only receive as well as those that can only send. [Answer] The sender has no access to electronics, but knows enough to create a battery or generator, and has some pieces of wire. That is sufficient to build a [spark gap transmitter](https://en.wikipedia.org/wiki/Spark-gap_transmitter). For this purpose, a very noisy, wide bandwidth, transmitter is good because the sender does not know what frequencies will have anyone listening. The hero is going to get an intermittent buzzing noise on a simple receiver. They will then have to find a reference for Morse code to interpret the messages. The messages include information about the location of the sender. The hero has the materials, fuel, and knowledge to get an autonomous drone aircraft working and programmed to land at the sender's location, but will need to use some of the components of the hero's radio receiver. Once the drone is sent with a piece of paper containing the one-shot outbound message, the hero will no longer be able to receive messages. Modification following an edit to the question. There is only enough fuel for the drone to make one trip. The hero puts his only radio receiver in the drone, irrevocably transferring his ability to receive messages, and builds his own spark gap transmitter to send messages. [Answer] Yes, this is very plausible. A transmitter sends signals. As long as the transmitter is transmitting a signal and as long as the transmitted signal is powerful enough to be received, your character should be able to detect it so long the radio being used is compatible with the modulation of the signal. Provided the signal is sent by a radio transmitter it should be able to be picked up by a radio. While it may be difficult to convert a modern day IC radio to transmit a signal, with access to basic electronic devices, building a really simple transmitter can be done with the appropriate skill. Note that to transmit a signal, a power source is required. It is much easier however to build a receiver than a transmitter (see foxhole radio [ <https://en.wikipedia.org/wiki/Foxhole_radio> ]) [Answer] Radios use hundreds of times as much power when transmitting than when receiving. Furthermore, due to how batteries work, output voltage sags under load. [The more power you draw, the more the voltage drops.](https://www.mpoweruk.com/images/discharge-C-rate.gif) As a result, a two-way radio with a mostly discharged battery can happily receive transmissions for many hours, but rapidly die as soon as you try to transmit. [Answer] Imagine an old, tube-powered, pre-heterodyne, short-wave radio. In general, you can rewire the local generator of the receiver in order to use the audio-frequency amplifier as a last stage radio-frequency transmitter. In the transistor case you generally can't, because audio-frequency power transistors are quite different from RF power transistors and you have a PCB with etched wiring. With tubes, in practice any tube is good at least up to 30MHz and the wiring is 3D soldered links and elements. You just need to know what you are doing and be careful not to damage some element when resoldering. For half an hour you are good. Maybe. For the needs of your plot, the character may break something in the process. ]
[Question] [ EDIT: Calculations were incorrect, the earth in my comic is not 5.8x larger, it is 2.4x larger. Its surface area is 5.8x larger but the diameter is 2.4x larger. Anyway I'm working on a comic that is set in an alternate earth that is 2.4x larger than the real world in an effort to incorporate numerous fictional locations that could not fit on a real-world map due to their sizes. I am wondering if earth that is 2.4x larger would slow down human progress to a significant degree due to the fact that travel times would be extended, thus slowing trade, immigration, and colonialism. This comic aims to be set in a modern world albeit on a larger Earth. The USA still exists but it's a much larger country. New Jersey, for example, is now the size of England. Likewise, the repercussions of this larger earth may inhibit the USA from ever coming into existence. If the answers result in any conflict with the goals of the comic, I may just resort to pure fantasy but it will be fun to learn how this stuff works regardless. [Answer] Yes and no, and possibly "it depends on what you mean by "civilization". As L. Dutch already noted, technological development is more a function of available resources and population density. On the one hand, it's quite believable that population density could increase at least as quickly as on our Earth, and indeed, perhaps faster given how much more real estate is available. On the other hand, it's not entirely unreasonable to believe that people would tend to spread out more given the available space, which could lead to less socializing in general, towns and cities being slower to develop, etc. Also, even if this doesn't happen on a global scale, it's possible that globalization will be slower, that you'll have e.g. Europe with the technology level of today while Asia still doesn't have electricity. In particular, note that your oceans are 5.8x as big, which makes them significantly harder to cross. There is a very real chance that Columbus did not "discover" the New World and South America was never exposed to Europeans. It's even possible that Vikings never found it either. (We'll probably still get there, though, but across either the Bering Strait or the island chain between Russia and Alaska.) By the era of steam ships, "the West" should be accessible, but that's a big ocean to fly across. If you think trans-Atlantic flights are brutal in our world, flying from Europe to America takes days. *Days. And you have to stop multiple times to refuel. Iceland and possibly Greenland are huge* transportation hubs. That, or no one even tries to cross the Atlantic ocean. (To put this in perspective, crossing the Atlantic in your world is on par with circumnavigating the entire planet in our world. Keep in mind there is nowhere to stop while you're doing this; you have to carry all your food/water/fuel with you. Crossing the Pacific? Australia to South America? Circumnavigating our world twice. Prior to the Space Age, there's a very real chance that the Pacific is still labeled "here be dragons"... and if dragons are dinosaurs, that label might even be correct.) Hawaii is of particular note. It's pretty remote already, and shipping stuff there isn't cheap. In your world, it's quite possible that, if it's inhabited at all, they have to make do almost entirely off their own resources. --- [Clearer](https://worldbuilding.stackexchange.com/users/2229) points out that humanity is believed to have started in the vicinity of what is now Kenya, an area not historically known for civil or technological development. It is, however, in the more hospitable part of Africa, from which one would expect humans to at least find Lake Victoria. Having accomplished as much, Lake Edward / Lake Albert are only (in your world) another 200-300 miles away, at which point you're on the upper bits of the Nile and can expect people to find Egypt and the Mediterranean... which are known for developing the earliest civilizations. Accordingly, you might be looking at a longer period before the start of civilization, but once those regions are settled, all the other information / answers apply. [Answer] Civilization is the inevitable result of agriculture: people needed to band together in a fixed location to protect their crops before and after harvest, and they need written records to track who owns what. This happened on our Earth about ten thousand years ago in three places roughly simultaneously: Central America (corn), the Middle East (wheat) and the Far East (rice). As those early civilizations grew, they spread north and south in search of more land for their crops—and discovered other crops to farm in the more temperate climates. Within about four thousand years, most habitable regions of Earth were "civilized". Since there was no more free land, continued population growth (also a result of agriculture) resulted in wars to take existing farmland from others, and empires were born. (Notice that Creation is usually placed somewhere between those two bounds, depending on when each civilization was founded and thus the start of their historical records.) On a larger planet, agriculture will likely be discovered at more longitudes, but there will be more latitude for civilization to travel (assuming a similar ratio of land to sea), resulting in a slightly longer spread from each origin. That might be easier, though, since the climate should vary more slowly, and maybe (handwave) that cancels out. Empires depend on the speed of communication and armies, so at least prior to industrialization, they would probably be similar in absolute size to our historical ones. Once you have mechanized travel and electronic communication, though, all bets are off. OTOH, more people means technology should progress much faster, so they may not have spent as long in the pre-industrial era as we did. [Answer] # One big aspect to a bigger world is stronger gravity. (For the long version: Go read "Dragon's Egg" and "StarQuake" by Robert L Forward. The gravity there is 67 billion times stronger than Earth's, but I think you'd find some of the ideas relevant.) ### Biology Flying birds? Insects? Possibly not. Jumpers (fleas, grasshoppers, frogs)? The impact at the end of that jump will be significantly more dangerous. Trees will be shorter. Climbing much harder. OTOH, dropping things out of that tree onto whatever is below will be disproportionately effective. Falling out of a tree would be certain death. Bipeds probably wouldn't be a thing. Falling down in such potent gravity would be Very Bad. ### Geology On the one hand I would expect mountains to be shorter. On the other hand I would expect tectonic forces to be stronger. More/stronger earthquakes, with more fault lines? More gravity means stronger eruptions when they happen, though the blast wouldn't carry debris as far. Ash clouds would still be a thing... probably? Waterfalls would hit considerably harder from a given height, though the heights available could be shorter. Cliffs can't be as tall before collapsing. ### Civilization/Technology Shorter buildings. A "2 story building" might be a modern miracle. Or a roof for that matter. Mining is that much more dangerous from cave-ins. That means fewer available resources. Strip mining suddenly looks really good. Flight and space flight won't happen until much further along the tech curve. No satellites (comm, spy, weather, etc) of any sort. Falling rain could be dangerous. Rain could also be a better/viable power source. Hydroelectric would be more effective. ### Combat Ranged combat will be at much shorter ranges, though I suspect it would still exist. Melee combat will be affected, in that overhead swings will be even more effective, but would require that much more strength to pull off. [Answer] Humankind would spread more slowly, more human species could share same epoch and even the Homo Sapiens could split in two ou more different species. In some point after all those different civilizations would make contact one each other and cause wars, genocidies, and all sort of shameful things, in a process would take thousands of years instead the few five centuries. Until something like Enlightenment and an industrial revolution appear and be prosperous would take a long time, any tentative still in the barbaric time would be quickly crushed. Demands lots of accumulated knowedge and a strong stable culture. In a giant planet could the industrial revolution happen multiple times, perhaps in different humans too, with few or none contact between them, like in the past Egypcians, Mayan and Olmecs; or Greece, China and Persia around 2500 years ago. Hard to know what would happen with high developed civilizations, in similar pace, if they would cooperate or compete. At end, cooperation or competition will be more decisive than the size of world. [Answer] The speed of movement would depend only the means of movement. Larger territories would require more time to be crossed, but won't make travel happen at a slower velocity. It is true that longer time to travel would be a minus, but as a plus you would have more available resources and more space to expand small civilization. Don't forget that available space is a big constrain on how big a population can grow. And all civilizations started on a small scale. Rome and its empire started from a small village of shepherd. All in all I think there would be no appreciable differences with respect to our own history. [Answer] It depends. Remember that most (all?) historical civilizations developed within fairly limited areas: the Nile Valley, the area around Greece & later Rome, the eastern coast of China, &c. So they could perhaps happily develop their own civilizations on a larger planet, ignoring the rest of the world - as for all practical purposes most historical ones actually did. Now what could cause a problem is that if you are just scaling up Earth, with all the geology & geography otherwise the same. The problem is that to have a Bronze Age, you need copper and tin in reasonable proximity; likewise, to have an iron age you need iron ore and coal. Are your world's Phoenicians going to be able to sail 5.8 times as far to bring back tin? [Answer] I would imagine a slower pace in the beginning but later it would catch up very quickly and then exceed our current earth by far. In the initial stone age, more available land to keep surviving with a hunter / gatherer lifestyle means less incentive to develop agriculture. Later as agriculture is discovered, more available land means longer time until sufficient population density is reached to have large cities. Once you reach the Renaissance era, the pace would still be slower because the larger oceans are harder / impossible to travel. However eventually they would reach the industrial age, possibly much later but I see no reason why they wouldn't eventually get there as conflicts / trade drive knowledge forward. I d say that once that giant earth reaches the industrial age, growth would be much faster. They would zip past the current age much faster, with way more intense globalization and sheer higher number of researchers boosting research to levels way above ours. Imagine where we would be if earth population was 40 billion instead 10B. We d already have cured cancer, mastered cold fusion, travelled to Mars etc.. with 5.8x ressources poured into R&D [Answer] I always wonder why people ended up in Australia 50,000 years ago, when the world was almost empty. If Australia had been 5.8 times further away from the cradle in North Africa I'm sure humankind would have ended up there all the same. Not because scarcity dictated it but because they could. Sedentarism was not driven by the first agriculturers being crowded out of the hunter-gatherer civilization. European states colonized because they could, not because they needed to. [Answer] A lot depends on how you want to define progress. Most answers seem to assume it is driven by population. But actually a lot of tech is driven by war. In realistic terms conflict would take a lot longer to arise as humans populate the Earth before being dense enough to get into real conflict. Personally I think it's quite possible we may go extinct at one of the ancient population bottlenecks and Neandertals may still be around. It's too broad a question to go into detail, but you could basically build several totally different stories from that same beginning. [Answer] Even if the density of that planet is smaller than that of Earth, so that the surface gravity is the same, the gravitational well is deeper. This means space travel is much more difficult. Crewed spaceflight possibly would not be achieved at this technological level and the number of automatic satellites is much smaller. Putting just a tiny can in the orbit is a huge endeavor. [Answer] Even if the question is marked as answered I think that the main point is missing. The world population boomed when the use of tools and eventually the industry multiplied the capacity to transport and produce food and goods beyond what is possible with human and animal muscles. To transport and produce people need energy and if the weight is stronger people would need a lot more energy, however the fuels we know in a heavier world would have the same energy density. So to keep the same level of development we had in the last 200 yeard the population would need an amount of energy resource bigger by one or two order of magnitudes. Furthermore some tasks could even become impossible because they would require fuel with a very high energy density. ]
[Question] [ In the question [How to safely knock someone out](https://worldbuilding.stackexchange.com/questions/101134/how-to-safely-knock-someone-out), it was explained to me that there isn't such a way. In which case, for a prospective superhero with super-strength and super-durability, what would be the safest way to capture random thugs off the street for the police to collect? Assume that the thugs pose negligible threat to the superhero. EDIT: When I said safely, I meant safely for the thug. The hero doesn't want to risk Grievous Bodily Harm charges later. [Answer] If a lion, a tiger or an alligator, though being able of crunching an animal with a bite of their jaw, can gently hold and carry their cubs using the very same jaws, I can imagine that also a superhero, though being super strong, is able of modulating the strength he exercises. Using this modulation he can restrain the tug and, once restrained, use conventional immobilizers like handcuff or ropes to secure that the felon won't escape justice. [Answer] Handcuffs and gentle handling is possible, of course, but what about using mere intimidation? From your questions it seems that we're mostly dealing with common thugs, not some insane revenge-fueled supervillain. Common thugs are very much human. If your superhero is able to show a display of overwhelming raw power, such as shrugging off any attack the thugs do or bend/crush nearby solid objects, then perhaps the thug would realize that giving up is the best thing they can do in the situation. Having increased speed may help too, to make the idea of escaping all but impossible. "Just give up and nobody needs to get hurt" and all that. Only once all of that fails would you resort to physical capture, preferably as effortlessly as possible (Swiftly handcuffing them, easily lifting them off the ground as if they're small children, etc) so it would further cement the image of overwhelming power once the story spreads all over media. In fact, once you've done this often enough, your reputation will probably precede you and your mere presence would be enough to intimidate nearby thugs to turn themselves in. [Answer] Big bag. [![raccoon going into bag](https://i.stack.imgur.com/qMqgI.jpg)](https://i.stack.imgur.com/qMqgI.jpg) from <https://www.youtube.com/watch?v=S-frp2gYp2I> "Getting them in the sack is the hard part". Your super has a roll of big fabric bags. He has them made special. They are tough. He opens one up and then pulls it over the criminal. Then he closes up the top. It is easy for one super to carry a lot of criminals in their bags. If you have a knife you might cut your way out. These bags have steel threads (like those in steel belted tires) woven in which makes the cutting very slow. If you have a gun you could shoot through the bag. That would let individuals express their frustration at being in the bag but will not otherwise help much. Other criminals in other nearby bags will probably yell at the shooter to stop. A fabric bag will not cause a criminal to suffocate. The criminal could still use a phone from within the bag. Bags are washable and reusable which helps the earth. When you want to ask a criminal something you could let him poke his head out of the bag. If he is helpful you could let him leave it out. I do not think you should do that with a raccoon. [Answer] Just do what the police do, and put the bad guys in handcuffs. They use those for a reason. [Answer] If super strength is the problem, you need to do something that involves as little body contact as possible. The best case scenario involves no contact at all. So the best possibility with current technology is tasing the bad guys, just like the police do sometimes. The worst thing that can happen is someone being hit in the eye or neck. Failing that, tranquilizer guns. Same risks as tasers, though not as safe. If the hero is not willing to use handheld weapons, and supposing their lungs are as strong as their arms, he or she could just shout out so loud that the thugs would be stunned. You may end up giving innocent people some level of deafness, but then again you can't make an omelet without popping some eardrums. [Answer] By the clothes; if they don't have hem, by the hair. Otherwise I think of it as catching a bird, you need to fold it in a natural way as fast as possible to immobilize it. For a human the best way might be to hold it by the ankles (both if possible) and raise it in the air, slowly, guiding it so it keeps straight. If it falls down, you would shake it so to be suspended in the air overpowered (like in a roller coaster), then as it falls, catch it by holding the abdomen. If it still fights, then fold it (in two) against your body. ]
[Question] [ I'm writing a short story about space faring race of people. I want to emphasize how technology has allowed a casual approach to space, making it seem like only a minor inconvenience or hazard. One way I'd like to show this is with space suits that are as minimal as possible. I'd like for it to be just a gas mask to go with their regular attire; something lightweight to use in emergencies or as needed that creates an airtight seal. (Also suppose that their future™ clothing takes care of sealing up the remaining cavities) My question is: would this work? Humans have survived total vacuum with no lasting effect. But in each case this has happened, their lungs have always been at the same ambient pressure as the outside. Since this mask supplies pressure (not necessarily as much as 1 atm; not necessarily air), there will be a non-trivial outward delta-p. Is this viable? Painful? Fatal? If the latter, is there anything I could do practically to make it work? [Answer] First: how little pressure can a human cope with? The [Armstrong limit](https://en.wikipedia.org/wiki/Armstrong_limit) is 0.0618 atmospheres or 60,000 feet altitude. Water boils and we can't have that in our lungs. At lower pressures the amount of oxygen, even pure oxygen, is not enough. From the above linked article. > > At 11,900 m (39,000 ft), breathing pure oxygen through an unsealed > face mask, one is breathing the same partial pressure of oxygen as one > would experience with regular air at around 3,600 m (11,800 ft) above > sea level. At higher altitudes, oxygen must be delivered through a > sealed mask with increased pressure, to maintain a physiologically > adequate partial pressure pressure of oxygen. If the user does not > wear a pressure suit or a counter-pressure garment that restricts the > movement of their chest, the high pressure air can cause damage to the > lungs. > > > So we need oxygen under pressure. That is what your space face mask would deliver. Doable? Pressure in the lungs requires a balancing atmospheric pressure as delivered by a pressurized suit, or by the column of air towering over my house. If you just pump pressurized air in to the lungs, the pressure differential causes [barotrauma](https://en.wikipedia.org/wiki/Barotrauma) . Barotrauma happens to people on ventilators when air under too much pressure is used (in an effort to overcome stiff sick lungs and get the O2 in). Barotrauma can happen when a diver breathes pressurized air at depth and then ascends holding breath. The pressurized air in the lungs, no longer balanced by an equal external pressure from the outside water, expands in the lungs. Your chest swells as your lungs increase in size. Hopefully you exhale and let it out! Too much and the air bursts out - either into body tissue spaces outside the lungs or into the bloodstream. That last is an air embolism which can kill or cause a stroke. <https://www.bookyourdive.com/blog/2012/6/28/never-hold-your-breath> But positive pressure ventilation is definitely used, all the time. People on ventilators are often ventilated with air slightly above atmospheric pressure: this is positive end expiratory pressure, or [PEEP](https://www.ncbi.nlm.nih.gov/pubmed/17368169). It is related to continuous positive airway pressure or CPAP which people use at home to prevent sleep apnea. So we can breathe pressurized air. Barotrauma occurs when the pressure is too much over ambient. On a ventilator 20 mm Hg PEEP (20 mm Hg over ambient pressure) is when it really starts getting to be too much. Could 20 mm Hg pressure in the space mask deliver enough oxygen? From the above, 39000 feet is 0.19 atmospheres pressure, which is 144 mm Hg. Breathing that much unopposed pressure you would pop. If only there were some way to make the effective oxygen concentration greater than plain oxygen gas, which you have to have under pressure to get enough in there. Gas is so gaseous. Could one achieve adequate O2 concentration at a very low pressure with some oxygen carrying liquid like perfluorocarbon? Breathing oxygenated liquids is called [liquid ventilation](https://www.ncbi.nlm.nih.gov/pubmed/17368169). Maybe the system would flood the lungs and face mask with an oxygen carrying liquid, and on reclaiming it into the reservoir with exhalation oxygenate it a lot under pressure / remove CO2, then allow the user to inhale the liquid again. The Armstrong limit above is 46 mm Hg and so even with the liquid ventilation, body fluids would still be boiling and that has to be bad. I would like to have this work somehow but I think your people are going to need pressure suits. They can be very sleek, form fitting suits like speed skaters wear. You can put some people wearing them on the front of your paperback. [Answer] No a facemask isn't sufficicient to protect a human like being from the vacuume of space. First off such a contraption would only provide breathable gas. That is only one of the functions of a space suit. Such a suit would provide no protection against the vacuum of space, or the extreme temperature differentials experienced during a spacewalk. Since they are exposed to a breathing gas there will be a positive pressure in their lungs. To contain this positive pressure requires a full space suit. When Joseph Kittinger's was glove failed to pressurize during his balloon jump, it swelled up to twice it's normal size and caused him debilitating pain, taking 3 hours to return to normal size. [Answer] As has been pointed out you need more than a mask because you need to contain the pressure also. However, you can do it with a lot less than NASA-issue if you are in a reasonably hospitable environment. The thing is, the limbs do not need air, merely pressure. A very carefully fit compression garment will protect the arms and legs from vacuum, you only need a pressure vessel around the head and torso. Not only do the arms and legs not need to be completely airtight but there's an actual advantage from making them not perfect--our normal cooling system is by perspiration. If the limbs are a bit porous the body can cool itself. Such a lightweight suit does not provide cold protection or extreme heat protection, it's acceptable in somewhat controlled environments (say, inside a structure that doesn't have air) but not good if the temperature extremes are too harsh. It also provides very little protection against micrometeorites. Inside, however, it would be much preferred by the workers as it's not nearly so tiring to use as a regular space suit. [Answer] Living humans have been exposed to the vacuum of space before, in a very unfortunate [accident](https://en.wikipedia.org/wiki/Soyuz_11). > > [...] they found all three men in their couches, motionless, with dark-blue patches on their faces and trails of blood from their noses and ears [...] > > > [...] Flight recorder data from the single cosmonaut outfitted with biomedical sensors showed cardiac arrest occurred within 40 seconds of pressure loss. [...] > > > The autopsies took place at Burdenko Military Hospital and found that > the cause of death proper for the cosmonauts was hemorrhaging of the > blood vessels in the brain, with lesser amounts of bleeding under > their skin, in the inner ear, and in the nasal cavity, all of which > occurred as exposure to a vacuum environment caused the oxygen and > nitrogen in their bloodstreams to bubble and rupture vessels. Their > blood was also found to contain heavy concentrations of lactic acid, a > sign of extreme physiologic stress. Although they could have remained > conscious for almost a minute after decompression began, less than 20 > seconds would have passed before the effects of oxygen starvation made > it impossible for them to function. > > > I'm not a medical doctor, but I'd assume all of the above to happen even if they wore a gas mask, except for the being unable to function due to oxygen deprivation after 20 seconds, and the subsequent loss of consciousness. However, it's prudent to acknowledge that various sources state the cause of death as... > > the cosmonauts had died of asphyxiation > > > ... which a pressurized gas mask that's specifically designed to work in ultra low pressure environments presumably could have prevented. [Answer] These are not humans, but a race of your invention. So just make them more tolerant of vacuum conditions. Like the created humaniform beings in Stross’ Saturn's Children who don’t need a suit to cross vacuum briefly, and need only warm coats on Mars. [Answer] ## Yes - it will work In case if - Also suppose that their future™ clothing takes care of sealing up the remaining cavities In the case, you do not need a gas mask, as strong plastic-bag-like stuff from the same material as clothing will be sufficient. But basically, you need some kind of smart matter. It can be not the gray goo like smart matter, but CNT fiber like smart matter will be sufficient for the task. It can work on any principles from the links from the [answer](https://worldbuilding.stackexchange.com/a/48004/20315) combining protection and muscle amplification functions. It can be transparent or appear as transparent to the user. It might work as a thin layer on the skin surface of the user, it might have some construction in the lungs and guts of the user etc. There are numerous ways to implement the needed for you functionality. It might be made from [CNT](https://en.wikipedia.org/wiki/Carbon_nanotube) or [DNT](https://arxiv.org/ftp/arxiv/papers/1511/1511.01583.pdf) (Diamond Nanothread). So yes causality of vacuum is totally possible. As a way to build in computer-like structures in the construction, you might refer to [Nanostructure-Based Vacuum Channel Transistor](https://www.nasa.gov/ames-partnerships/technology/technology-opportunity-nanostructure-based-vacuum-channel-transistor) should work well with those types of materials. [Answer] You can have the people genetically engineered to have vacuum-resistant lungs and maybe cardiovascular system, so they can use a face mask and not get an embolism. Another possibility is Kurzweil's artificial red blood cells, which could keep them oxygenated for minutes to hours without breathing. [Answer] A 'gas mask' usually means a respirator which consists of a mask and filters, sometimes exhalation mask to reduce breathing effort. Depending on type the filters can provide protection against particles, aerosols and some types of vapour (usually things like organic solvents with a relatively high molecular weight). What this type of mask won't do is provide any protection at all against a lack of oxygen. Having said that some types of mask can be fitted with can replace the filters with a regulator connected to a pressurised air supply, the SCBA systems used by firefighter are based on this principal. You can also get [emergency systems](http://www.safetyliftingear.com/products/emergency-escape-breathing-apparatus/escape-kit-10min) designed for escape purposes eg in confined spaces ect. These only give a few minutes or air and aren't necessarily designed to work in a vacuum but would probably be better than nothing and are deigned to be very simple to use in an emergency. . Another real world analogy is the emergency oxygen masks in passenger aircraft which are designed to keep passengers alive if the cabin depressurised. These sort of systems would be OK say in the event of a hull breech when you just need to stay alive for long enough to patch the leak or escape through a hatch to another compartment. If there is a risk of ending up in space by accident, say if there is a decompression and no immediate escape route it might be worthwhile haveing a suit which can self inflate (a bit like a self-inflating life jacket) in tandem with an emergency breathing mask. This would provide additional protection from the effects of reduced pressure on tissues at the expense of making you effectively immobile but that might be ok if you just need to float around for half an hour until a rescue team in proper space suits can arrive. As long as the suit and mask are separate you don't even need the inflating gas to be air. You could also have a suit which provide mechanical compression instead of inflating. In a space station or space craft it might make as much sense to have emergency masks and refuge pods dotted around in the same way that fire extinguishers are in contemporary buildings. ]
[Question] [ I'm building a world but I keep coming across the idea of putting an ancient race in the mix similar to that in the mass effect or halo story lines. However, I feel like it has been over used lately. It really makes my story more believable but I think it takes away from the story at the same time by making it seem less original if that makes sense. Without getting into a lot of detail, several different sentient species develop simultaneously on different planets in a solar system with planets that are in very close proximity to one another and most of the story takes place when the other races discover one another. If you read this far you might understand part of my dilemma because of how improbable this story sounds. Without creating a back story of an advanced alien race that basically manipulated the solar system to this are there other probable explanations? [Answer] It's actually not completely improbable. There are meteorites on Earth that [originated on Mars](https://en.wikipedia.org/wiki/Martian_meteorite), and it's possible that there are others which originated from Mercury or Venus which haven't been identified as such yet due to lack of comparison data. It has also been hypothesized that microbes could "hitch a ride" between planets on meteorites. Similar reasoning is why NASA crashes its [Saturn](https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens#Spacecraft_disposal) and [Jupiter](https://en.wikipedia.org/wiki/Galileo_(spacecraft)#End_of_mission_and_deorbit) [probes](https://en.wikipedia.org/wiki/Juno_(spacecraft)) into their planets at the end of their missions -- they don't want to risk contaminating one of their moons accidentally. So it's not unreasonable to imagine the following scenario: 1. Primitive life evolves on one of the more central planets fairly early in the development of the planetary system. 2. One or more impactors on the life-bearing planet scatter microbe-bearing meteorites into interplanetary space. 3. Some of these meteorites land on other planets in the system. 4. A small number of microbes survive the journey and begin evolving on their new home planets. 5. Due to circumstances, evolution progresses at roughly the same pace on each planet, resulting in them each bearing at least one sentient species at a given point in time (e.g. when the story takes place). The last point isn't actually unreasonable. Depending on how you measure sentience, Earth currently has quite a few sentient or near-sentient species: [primates, corvids, cetaceans, octopi](https://en.wikipedia.org/wiki/Animal_cognition), etc. Early ancestors of humanity have been around for hundreds of thousands if not millions of years, and its possible that our descendants or the descendants of one of the other sentient species on this planet will continue to exist for millions of years to come. [Answer] # Colonization -> Dark Age This is another well worn trope, e.g. Vulcans and Romulans from Star Trek, but the alternative is that a group from planet A colonized some of the other planets, but then the civilization collapsed on the initial planet. The big advantage of this trope is that all the civilizations have the same development starting point only a few centuries in the past, which makes becoming aware of each other at the same time much more probable. I don't think this is as implausible these days as it seemed many years ago when the trope surfaced. First off, you only have to look at our own space program on Earth. Did you know that the last man on the moon walked there Dec 1972? That is now 44 years ago. For reference that 44 year gap is the same between the Wright brothers and the first supersonic flight by Chuck Yeager. Second off, the mechanism by which civilization wounds itself has become clear. Climate change going over a tipping point of some sort, while I consider it pretty improbable in reality, makes a great storyline. You don't have to destroy civilization on the first planet at all to set it back a century or two. The concept of migrant hordes from the poorer tropical regions flooding the more advanced parts of the world is more or less a reality. If you consider the current migrant problem in Europe was caused by a war in a country of 25 million, what would happen to 1.3 billion Indians if the monsoon failed? It is easy to imagine a situation r where wars over limited space consume the planet. Maybe sprinkle a few nukes in for good measure. A last story aspect that has come up on this site a lot recently is [Kessler Syndrome](https://worldbuilding.stackexchange.com/questions/63923/how-can-i-prevent-kessler-syndrome-among-space-stations). A Kessler catastrophe around the home planet could put space exploration back by centuries if it was catastrophic enough, not just from making space launches hard/impossible, but by politically convincing the people of the home world to abandon space. As for the colony worlds, they could lose contact with other worlds through low population and lack of expertise. Imagine a colony of 1000 that is focused on farming and terraforming. The knowledge of how radios work could be lost in a generation if there were no radio/electrical engineers around in the first place. Cut them off from the main planet, have them focus on survival and a few centuries could turn the home world into a half-remembered myth. Put some of these things together, and it is not too hard to imagine a 200 year or more gap between colonization and the re-entry of some of these worlds into space. That might get you what you want. You could have situations where several colony worlds make it into space together to find the ruins of the homeworld, or the homeworld remembers the colonies but has ignored them and space for centuries. [Answer] ## Space/Time Rifts No need for an alien race. Assume only one inhabited planet to start (a variant would be multiple, but to keep it simple, assume one for now). Have a rift "Event" in space/time appear on that planet in different locations on that planet --- with the other side of the rift being the other planets you desire to populate. Then, some of the inhabitants from those various locations go through (or are shifted through - perhaps an entire city gets scooped up and moved) and end up on these other planets. They will have been roughly equal developmentwise before the "Event" and being shifted to their new home worlds. But, their new home worlds could alter them genetically and technically and perhaps morally. When they meet for the first time, they may have some common race memories which could make for some interesting interactions, but, they will also have developed so far away from each other over tmie that they are essentially alien to each other. [Answer] Ancient Forerunner Race Solutions... * Your entire solar system is an abandoned zoo full of species from across the galaxy. * Your entire solar system is a homework assignment or thesis by an ancient student of biological adaptation to planetary conditions. * Your entire solar system is a Casa Blanca style safe zone for refugees in a galaxy scale war between two ancient alien races. Solutions without a Ancient Forerunner Alien Race * Your own species once colonized the entire solar system, using genetic manipulation to adapt some of your kind to each of the planet's environments. That advanced, space faring civilization then collapsed leaving each planet to evolve independently. * A flaw in your specie's genetics has caused widespread dementia and xenophobia through your population. The other planets are all actually lifeless, but everyone sees aliens everywhere they look. * Virtual Reality! Yep, each planet is populated by a separate city's best VR players and they are all competing in an immersive delusion which utilizes memory altering drugs to convince the players that the simulation is real. * And my favorite... It just happened (because God has a sense of humor and likes watching His creations fight) New Ideas after reading @SRM's excellent answer... * An enormous herd of a non-sentient space-born predator species floats into your solar system and some fly down onto all of your planets to become the apex predator on each world. On most of the worlds, a sentient species evolves to wipe out the invaders. On one of the worlds, no indigenous species arises, so the invaders thrived and eventually evolved sentience as well. [Answer] Multiple species all "coming of age" at the same time is, most of us agree, improbable. You need to tie the emergence of sentience to an environmental trigger. That's what gives the "ancient seeder species" idea such power. So.., what other environment triggers are there that would affect multiple star systems? Well, pretty much only one comes to mind : a local nova. The ejecta of a star exploding would impact other systems. Let's assume that life is common on worlds -- an open question and still a plausible theory, despite the counterexample of our own solar system so far. Life is on all these worlds. Then the nova disrupts the ecology by causing a major extinction event and making the environment more chaotic for an extended period of time. We don't know what triggers sentience, but a world where survival demands problem solving would select for it. So you have your worlds equidistant from a nova and you posit that this opened the door to sentient dominance, all at the same time. And you argue that the laws of nature are structured enough that once sentience happens, the path to space flight is, in general, a straight path with a fairly fixed timeline, give or take 10k years. Sprinkle your worlds with a few species that are slightly slower to develop. You'd pass plausibility for me and, I suspect, other readers. [Answer] How "hard science" is your story? What is the tone? There are many pulp sci-fi stories with this basic concept. Parallel development and equivalent analogous technologies is a pretty basic trope, so it doesn't really need a lot of explanation so long as you are not trying to be a hard science author. The primary reason for an "ancient race", IMHO, is so there can be advanced tech artifacts lying around for the current populations to use but not really understand. Things like stargates. It lets you handwave stuff but still keep within a "Sci-fi" setting. It can also explain why Martians are just red skinned bikini clad babes (i.e. they are just transplanted humans) but E.R. Burroughs didn't even need that! Humans currently assume that technologic advancement is always forward and rapid, but we forget the thousands of years on earth when very little happened. So if you need a somewhat plausible rationale for simultaneous tech advancement across an entire solar system, perhaps your solar system went through a dense nebula that resulted in lots of orbital micro-bombardments and reduced solar input, so life got real hard on all the planets, effectively halting civilization for a few million years or so. But this allowed primitive life to all reach a similar sentient, pre-technological level. Then the solar system leaves the nebula and suddenly there is lots of sun light and rocks aren't falling every few years. So every planet is primed for a technological renaissance at around the same time as each planets version of Neanderthal kicks into high gear with agriculture and technology (look at all this metal ore just lying around!!). Bam, each planet is basically developing simultaneously and you can fudge it a bit so they all have fairly equivalent technological achievements. [Answer] What do you mean "developed" at the same time? Humans "developed" 2 million years ago, and modern humans 200,000 years ago. Human civilizations developed 10,000 years ago and modern tech levels developed less than 100 years ago. There are also falls such as the fall of Rome and the dark ages at the end of the copper age. There are civilizations that rise and fall due to others and some that do so due to their own stupidity. My guess is "how do you explain several close species developing star travel and roughly equal levels of tech at the same time?" Well Let's say they all developed within the last 200,000 years and are all within a 50 light years radius. At some point in those 200,000 years they all get to the point of writing, farming, etc... What does that mean in terms of today's tech? Nothing. Is it surprising giving 200,000 years? nope. Ok so some time after that point they reach the iron age.... How does that effect their technology as you'd see it? What exactly does that mean for history? Not much, because Greece, Rome, the Middle Ages, all exist within the same area of technology. Even science and the renaissance isn't going to matter much about when it happens. pre 1900s technology could go on for centuries, perhaps millennia and it wouldn't be surprising... It is only the Bessemer Process that really makes things start moving forward to the point where multiple civilizations of the same type at the same level likely won't exist in the same time frame. Well I sorta lied. A civilization that has the Bessemer process just makes expanding easier due to lots and lots of high quality steel. This allows civilizations to build large and build crazy contraptions like Plains, Trains, and Automobiles... as well as the eventual LHC, but ultimately this just means that the civilization can get up to the point of a global to solar system based civilization, but the next stage after this, for all we know could take millions of years which makes similar civilizations more and more likely. Sure they'll be at different levels of converting their solar system into multiple colonies, but ultimately they'll be at pretty much the same level. That's right, we're pretty much at a possible zenith that could stand for the rest of history, and there is nothing that says we'll decided to convert all matter in the solar system to habitats or just leave them as they are and live in harmony with nature more so. So you could have a species that has reached the same zenith who really have developed out the rest of their system or really young who have. They're both going to be roughly equivalent to each other at this point. Now the question is how do they all get triggered to look out to interstellar space at the same time... Well, what if they are all older than "Earth" and all realized radio waves were useless long ago and while they have developed superior communication techniques that are similar to radio waves, because radio was such a waste of time each of their civilizations all gave up and never tried with the better stuff and they all just happened to have those time frames of people looking and emitting radio waves were just out of sync, but then "Earth" happens upon that superior communications tech and they're all roughly x distance away from "Earth" and so everyone in that area get the same "OMG SOMEONE ELSE IS OUT THERE?!" at the same time and thus begin working on interstellar technologies all at the same time. Thus you have all the species both developed in the important areas at the same time, differences, and no "ancient alien" Oh! and BTW, the ancient alien thing doesn't really work, because of what I described above. If 2 species start at the same point it doesn't mean they'll get to the same point at the same time. Rome could have survived without the burning of Alexandria and humans could have been in space 2000 years earlier. Or Persians could have won against the Greeks and Humans may never have even reached the moon due to the change of western philosophy. [Answer] Assuming a planetary system with multiple planets in its goldilocks zone, just like TRAPPIST-1, then while is extremely improbable that several sapient species could all make contact with each other effectively simultaneously, it's not impossible. What people often fail to realize is that low probability events happen all the time. Even having an ancient advanced sapient civilization jury rig a planetary system's multiple habitable planets to have sapient species emerge effectively simultaneously would be itself a highly improbable event. Unless the advance ancients are doing this on a regular basis. An alternative solution to sheer improbability becoming a reality and advanced ancients is that a sapient species arises on one of the habitable planets. They expand into interplanetary space, conduct genetic engineering on the native lifeforms, their home planet succumbs to an apocalyptic catastrophe and the colonists return but their civilization regresses into barbarism, all memory of the space-faring phase of their civilization is lost. By the time it re-emerges the other planets have spawned their own civilizations. This is a local uplift scenario involving not quite advanced ancients but then removes them from the scene. [Answer] ### Modern race Instead of an ancient founders' race, what about a modern race? Openly acting they'd be gods, which may not fit with your story. But what if a race was acting behind the scenes? For example, there was a story called [Waiting for the Galactic Bus](https://en.wikipedia.org/wiki/Waiting_for_the_Galactic_Bus). Two brothers are stranded on Earth in prehuman times. Since they were bored, they made a few genetic changes to some apes to make them smarter and more interesting. Eventually civilization. In the [Hitchhiker's Guide to the Galaxy](https://en.wikipedia.org/wiki/The_Hitchhiker's_Guide_to_the_Galaxy_%28novel%29), the mice were in charge of the world, working as lab attendants. You can of course come up with your own aliens. Perhaps house cats run the world. Or blame the trees. James Schmitz wrote "The Pork Chop Tree" where psionic trees would alter every animal species to be dependent on it. In that case, it also got rid of pesky things like sentience. But perhaps your trees have a different goal. How do you build a transistor radio on a deserted planet? You need a semiconductor industry. Now in that case obviously you'd sacrifice making a transistor radio in favor of making something without as many requirements, e.g. a vacuum tube radio. But what if you couldn't? What if you needed a whole solar system's worth of resources to build the basic capability? Assuming you're effectively immortal (don't die of old age, only illness and injury; or can pass memories to descendants perfectly), you might plan to uplift species on each habitable planet. That way rather than having to wait for them to spread out and colonize, you can uplift multiple races simultaneously and grow their populations at the same time. Each race can specialize in different things so that when they combine, they'll be strictly more capable. Your aliens may not have opposable thumbs. They may be accustomed to work with others who handle the more active tasks. Perhaps they simply don't reproduce often enough, or they happen to be missing a sex. So populating the planets themselves is not feasible. It's a similar trope to the ancient founders' race, but not the same one. Which could allow you to make it fresher. [Answer] # We were them. We built this civilization. After that * some catastrophe happened * a civil war happened * our civilization went into a bad direction ([example](http://en.wikipedia.org/wiki/Communism)), and after thousands of years of slavery we degraded and fallen apart. [Answer] The ancient race is not so ancient. In fact it is still around You ancient races actually around today they are hiding from an old enemy and trying to give the impression that they've been wiped out so they leave their ruined cities above ground while they secretly live in high-tech underground bases. [Answer] I think you could tie in a group of sentient beings that have managed to contact each other through magic or telepathy and are therefore already aware of the other planets and have their own agenda - They have alway known of the existence of the other worlds and have used that knowledge for their own purposes and have shared their development with each other to suit their own desire to connect with each other or achieve some mystical, magical goal. ]
[Question] [ In 2024, NASA detects a pair of planetoids, each the size of the earth's moon, careening towards our solar system. The good news is that they're set to enter earth's orbit without any collisions (how this happened is the purview of another question). The bad news is that having 2 more moons will cause massive tidal waves, tornadoes, and countless other disasters that will cause human society as we know it to be destroyed. Needless to say, they freak out and spread the word that a planetary collision is incoming. By some miracle that is beyond the purview of the question, they manage to get the near-total support of everyone in power in the US and UN, successfully convincing anyone who might oppose their measures that it's better to be alive 60 years from now than comfortable right away. With that out of the way, they immediately set to work on an off-world habitat to which humanity could retreat and wait out the upcoming extinction event. It could be a space station, but it could also be a moon base or mars base. Given 60 years before the planetoids hit and total financial/political support from both the US and UN within reason for that entire time period, Where would they construct this habitat, and how many people could it sustainably support? Note that the US and UN will not bankrupt themselves over this, but they WILL transition to a war-time economy and give as much financial support as they can afford. Note also that the disasters are going to affect every inch of the crust, rendering survival on earth anywhere basically impossible for humanity as we know it for at least 30 years, and maybe even multiple human lifetimes. And 'anywhere' includes underground bunkers beneath the surface. [Answer] If space has to be the only solution (and as others have pointed out its very tough to get to work), then there is one obvious "best" location. First, lets consider your resources. It's difficult to predict what launch technologies will look like in the next 50 years. But we do know that reusablity is going to dramatically reduce costs, because it already has. SPACE WAS EXTREMELY EXPENSIVE. Getting to space has been historically extremely costly. A Shuttle flight cost around $2B in current dollars, and was so costly for two main reasons. One it was a government project built by cost plus contractors where components had to be built in all 50 states (massive solid rockets trucked from Utah to Florida?). More importantly it wasn't really reusable, it required hugely expensive maintenance. The Shuttle engines had to be entirely rebuilt every launch, the solid rocket boosters were destroyed on landing and only parts could be used, and a hugely expensive Hydrogen fuel tank was burned up every flight. Plus the rest of it required expensive maintenance between flights, the Orbiters critical heat tiles had to be carefully inspected and replaced. The Shuttle was the most expensive launch vehicle ever in cost per pound, around \$40,000 per lb for the payload (ignoring the Orbiter). Thats is the main reason why the ISS cost over \$150B to build. But now a Falcon 9 reusing the first stage can put about 2/3s as much payload in space for \$50M (about \$1,500/lb), and that's at a profit. REUSABLE ROCKETS WILL MAKE SPACE FLIGHT A LOT MORE LIKE COMMERCIAL AIR TRAVEL Over the next 60 years it's clear that fully reusable space vehicles will dominate space launch. Fully reusable means a rocket that can launch payload to orbit and all of the rockets components will return to earth where they are quickly and inexpensively inspected and refueled to fly again. SpaceX is building a design right now, the Starship, and even if Starship fails more designs are going to be attempted (RocketLabs Neutron is another) until one succeeds. The benefits are simply too massive to ignore. If Starship meets its initial design goals it will cost less than \$30M for 150,000 lbs to orbit, or about \$200/lb. But how much cheaper can a reusable rocket system get? Essentially when rockets can be reused hundreds of times they will have similar economics to commercial jetliners, where the most expensive cost becomes fuel instead of expending key components every flight (note that similar economics doesn't mean as cheap as). Starship is a Super Heavy launch vehicle, it will be the largest ever made, and its fuel costs are estimated at about \$1M per launch. Musks goal is to launch each Starship one hundred times to spread the costs of construction over many launches. If he achieves that the cost per flight can be as little as \$5M, or \$33 per pound to space. <https://space.stackexchange.com/questions/58161/what-is-the-lowest-the-cost-of-launch-can-get-to/58222#58222> You might also look into nuclear rockets like the NERVA project successfully test fired in the 1960s, but as I'll explain they aren't likely to offer better economics than a high cadence reusable chemical rocket like Starship for your obvious destinations. So great, we can lift large payloads and lots of people into space very cheaply now, where do we send them? THE MOON IS UNINHABITABLE Not the moon. It's an inhospitable desert lacking in resources. Water is only available on the poles and the rest of the moon is over 250 degrees for two weeks at a time, and near absolute zero with no solar power the next two weeks. There are lots of elements in the regolith you could try to melt out, but that's an immense amount of energy. And the regolith is razor sharp, so you must keep it out of crew quarters to avoid breathing it in. The reason the regolith is razor sharp is its never been weathered, it has no atmosphere which means every payload has to use a huge amount of fuel in order to land on the moon. MARS IS BETTER, BUT STILL NOT THE ANSWER Mars is better. It's much farther than the Moon, about a 3-9 month trip depending upon when you leave and the amount of fuel you spend. But it's atmosphere makes a huge difference. It actually takes less energy to go to the surface of Mars than the Moon because you can aerobrake into its atmosphere without using hardly any fuel. Its temperature range is less than half the moons because of that atmosphere. And it's awash with resources, CO2 for producing fuel and oxygen, ice water for many uses, nickel iron meteorites littering the surface. And the atmosphere has weathered the dust so it's not going to rip apart your lungs or space suit (though it does have slightly poisonous perchlorates that need to be washed off when anyone comes inside). But Mars isn't the answer either. First, going to Mars or the moon means you increase your fuel requirements as much as ten times from just going to space. The SpaceX plan for exploring Mars with Starships requires as many as ten or more tanker flights to refuel the Starship for the journey. Now your \$30 per pound cost just ballooned back to \$300+. Nuclear Rockets can't help you here, because of their required shape and shielding they can't use aerobraking effectively, so their power advantages are lost to Mars. And you'd have to send millions of tons of supplies, tools, and equipment to ensure the colonists had everything they needed to last as long as it takes for Earth to return to habitability. They'd have to be self sufficient. How do you make that happen? Maybe they could survive on nuclear power and hydroponic crops grown in underground shelters to avoid the higher surface radiation. But how would they repair things? How would they even make plastics? How would they get all the elements and organic molecules we take for granted on earth? SPACE OFFERS ONLY ONE CHOICE No you really only have one choice if humanity is forced off planet. Earth orbit. Its by far the cheapest and easiest place to send people. You can put at least ten times as many people in low earth orbit than on Mars or the Moon with the same number of launches. Its protected by the Van Allen belts giving much lower radiation than open space. Its super close meaning your cargo rockets can turn around quickly to fly even multiple times a day, far more often than if they were stuck on week long lunar trips or years long Martian trips. And if the conditions on earth ever improve briefly, say during specific orbital aligments, you'll be able to pop down to collect raw materials. At \$30 per lb you could launch the million pounds of materials to make another ISS for only \$30M. In reality the ISS is far too small to survive for decades on its own, you'd need to build structures a hundred times larger where a thousand times more people could live. They'd have to be redundant so that any leaks or damage could be isolated and repaired without the entire structure losing atmosphere. And they'd have to be spinning, because humans can't survive in zero gee for years on end without extremely damaging health issues. Essentially you need to build O'Neil Cylinders, large spinning cylinders where people live on the insides. Probably the smallest ONC that could provide for long term survival is at least a billion pounds (ten times the size of a Supercarrier). And they'd need a ton of redundant power systems. You can't just rely on solar no matter how strong it is, if your panels fade over time you need to be able to replace them or augment them with other power sources (like nuclear). Devoting 10% of the US Economy to this task for 50 years would give you about \$100 Trillion to invest in it. Using half the funding for payload launch at \$30 per pound, would put 1.5 trillion pounds of space station components (and supplies, tools, equipment, backup supplies/tools/equipment, etc) into orbit. The rest of the money would pay for building the components on earth, flying crews into space to assemble them and finally their inhabitants up to spend their lives in them. If you assume you need at least 20,000 lbs of structure, hydroponics, materials, tools, equipment, and their backups per person, each billion pound O'Neill cylinder would host 50,000 people, and you could have up to 1,500 of them supporting a total population of 75 million people. NEAR EARTH ASTERIODS AS RESOURCES You'd also want to investigate near earth asteroids that are within a few months of earth where you can get cheap access to millions of tons of raw resources without having to lift it from the earths surface. They contain water, carbon and metals like iron, gold and platinum. If possible you may want to divert some to orbit next to your habitats so they can be mined easily to augment supplies. RISKS Lastly you'd still have massive risks. Two new moons would throw the orbits of many near earth objects into widely unpredictable orbits. Massive meteor showers could destroy many of your habitats. Their own orbits won't be stable, they'd have to at least be at the higher parts of the low earth orbits where they won't be in danger of reentering the earths atmosphere for thousands of years. Even then they'll need fuel for orbital adjustments or end up being helpless to avoid any collisions, even with each other. [Answer] # 0. The amount of farming land required to support one vegetarian is measured in acres. The cost to launch a kilo of stuff into space is about 10,000 dollarydoos. This is too much to launch into space. The concept of evacuating to space is silly. When you evacuate you go somewhere safer. Space is the most dangerous place on Earth. I struggle to think of a level of devastation where you are better off living in a sealed capsule orbiting the planet, compared to a sealed capsule on the planet. This is even ignoring the cost of getting to space in the first place. Nope. Better to dig under the ground and build an geothermic apocalypse base. [Answer] ## From an astronomical point of view there are several scenarios There are two main possibilities: 1) the objects proceed in an elongated, elliptical orbit and 2) the objects follow a hyperbolical trajectory. In descending order of disaster level.. Unstable, elongated elliptical orbits in this case, a collision follow, some time in the future. The UN will want to invest a few hundred million of their funds to simulate accurately what is going to happen. If the orbits vary, danger is some day they would collide the planet. In that case, there is no chance of survival on the planet, nor in orbit. Better park your spaceship somewhere at Lagrange L2 and make it a generation ship ! These people will have to survive in space for thousands of years, at least, or settle on the moon, after Earth is changed into a wobbling fireball. No life remains on the planet. Stable, elongated elliptical orbits along a tilted plane. periodic, huge volcano outbursts, any coastal region will be hit by kilometers of water each tidal cycle. Changes in the atmosphere composition, and a permanent nuclear winter. The dust will eclipse the sun. Underground shelters are no option. Where would these poor underground people go? there will be no safe place left on Earth after several orbits, because the rotation will allow the objects to cause havoc on any location/latitude on Earth. Eventually, the Earth's crust will crumble and disintegrate completely, the heat of the friction causes the crust to partially melt. There is no way for any life on Earth to survive this. In orbit, it could be safer than in the above, unstable scenario, but your spaceship will need a good ion-thruster to compensate for tidal forces while in orbit ! it will need fuel.. and there is little hope of ever returning to the surface. The Earth has become a lava lake with hot islands. Stable, elongated elliptical orbits, both in Earth's equatorial plane. periodic, huge volcano outbursts, any coastal region will be hit by kilometers of water each tidal cycle. Changes in the atmosphere composition, a Tsunami kilometers in height, and a permanent nuclear winter. The dust will eclipse the sun forever. People can survive in underground shelters in the polar regions (bio-sphere's?), where the floods cannot reach them and tectonic plates are stable (e.g. Antarctic plate). The underground shelters would need a lot of energy to keep the temperature up. On the long term, the Antarctic ice could melt. The issue with any periodic scenario is more and more energy will be dissipated in the crust, causing volcanic lakes along the equator. One time event, hyperbolical orbits. They come at high velocity, let's hope they'll never return, or be caught by the sun. Along some fault lines and especially in the plane of the trajectories, huge damage to the Earth's crust is caused, there will be abundant volcanism and changes in the atmosphere composition, a nuclear winter. But after this pass by, there will be no more energy dissipated into the crust, after the event. The event would cause unimaginable floods, large part of your underground shelters will be crumbled and cooked in new volcanism, there will be world wide climate change.. most probably an ice age will follow, as a result of CO2, the equatorial region will be burnt to the ground. A mass extinction event, but thousands could survive on the planet surface.. and find a way to rebuild civilization.. [Answer] ## You Need to go to Mars There is only one scenario where these new moons could cause a world ending event, and tidal/wind sheer is not it. To even make this question make any since, lets assume these new moons settled in right at thier Roche Limit which for an Earth/Moon relationship is about 11,470 miles above the Earth. At this range the moons would pull on the surface of the Earth with about 360 times as much force as our current moon. Yes, this would create massive tidal waves ruining coastal cities across the globe, but keep in mind that this is still only about 0.001Gs of force so, not really enough to substantially effect life in-land. The real devastation though of these low orbital moons is from what the Earth will do to them. The Earth's gravity will slowly pull the moons apart causing a constant and massive meteor shower to pepper the earth. This meteor shower will devastate everything in its path, and kick up enough dust to block out the sun making the Earth uninhabitable for the entire foreseeable future of humanity. However, these new moons also create such a long-term hazard that you need to make a permanent plan for evacuation. Deep space or the moon will not give you the raw materials you need to maintain a colony for very long without support from Earth. While the moon has raw elements, they are all in undifferentiated regolith which makes it worthless as a place to mine for the things you need. Deep space has the opposite problem. Astreroids often contain large amounts of useful elements, but because each individual asteroid comes from a single type of star death, they tend to lack the diversity of elements you need without have to maintain a massive network of mining ships to go out and mine all the individual asteroids you need (and asteroids are not nearly as closely packed together as Hollywood makes them look). Mar's geological history makes it suitable place to find a wide range of useful ores that can be refined into whatever you need in economically helpful ways. These differences are the whole point of the Space X mission going to Mars instead of the Moon or deep space. ## Cost A Falcon Heavy rocket is the most cost efficient rocket we have to date and it can launch about 16.8 tons to mars for a cost of about \$9,077/kg. According to the SpaceX mars mission plan, using light weight inflatable infrastructure where possible, we may be able to colonize Mars at a total mission weight of as little as 3 tons per person. This is also much lighter than what a deep space habitat would be when you consider that you don't need to bring all your water/soil/etc. So, a Mars evacuation plan would cost about \$27.2 million per person in rocket costs plus probably a few million for all the high-tech infrastructural stuff; so, lets assume a cost of \$30 million per person. That said, if you plan it right you might be able to save even more people if your early colonists can build enough manufacturing capabilities early on, later missions wont have to send the whole 3 tons of stuff per person along. So, you might be able to get it down to closer to 1 ton per person in latter missions when you are only sending people with enough supplies for the trip itself. ## Budget The total wartime cost of WWII was about 4 trillion dollars (58 trillion in today's economy). Also consider that the Earth's population was only about 3 billion in WWII, and is about 8 billion now, and is is expected to reach equilibrium at about 9 billion within the next few decades due to shrinking average family's size. So if we consider this level of "war time spending" on a per capita basis over a 60 year period, you are looking at a total budget of about 2.5 quadrillion dollars in today's economy. This means you can build a self-sufficient Mars colony big enough for somewhere in between 90-270 million people allowing you to evacuate roughly 1-3% of the Earth's total population. But... there may be another problem here. While the money is in theory here, the natural resources may not be. It takes about 4 units of crude oil to make 1 unit of RP-1/LOX propellant for a falcon heavy engine. Since a falcon heavy has a fuel wight of 92,670 kg and a barrel of crude oil is 136kg, this means each launch requires about 2,725 barrels of crude oil... which is in theory enough to launch 3.6 billion people too Mars with our current fuel reserves; however, this fuel reserve will only last another 46 years at current rates of consumption from all the other things we are doing just living here in the mean time: and this is supposed be a 60 year plan. While you can probably get your first few million people off world at a reasonable price, as world oil reserves deplete, the cost of each mission will get much greater, and by year 45 there may be no oil left to fuel these missions. You can address this problem in one of 2 ways: #1 assume your program bought up and hoarded the oil you need early on and set it aside for later missions, or #2 assume that the oil crises the world will face in 20-40 years will destroy your economy and effectively cut your evacuation program short. How idealistic you are here will have a significant impact on the size your your mars colony. [![enter image description here](https://i.stack.imgur.com/rKWiK.png)](https://i.stack.imgur.com/rKWiK.png) [Answer] With a 60 years heads up, a lot of effort can be devoted to altering the trajectory of the incoming object, some of these methods can be relatively passive like altering the albedo, but even relatively small thrusts can have a large effect. The cost per kilogram per launch is already dropping (at least for low earth orbit) and will end up be in the 10s or hundreds of dollars per kilogram. If material can be extracted from the moon or asteroids costs continue to drop. Food supply, radiation, people heath mental and physical are probably limiting in almost all sensations though… [Answer] ## Half a million. I remember when smoke was rising the second Trade Tower, some of the news announcers started to speculate openly whether it might have been an act of terrorism. On that note, the pair of planetoids racing straight at Earth might at first arouse only timid consideration of how unlucky we are. But when they start decelerating so they can go into orbit? That would be a clue. Sending planets at an inhabited planet has a few explanations. Most of them (hungry monsters, borrowing Earth's ocean to refuel) don't allow for a lot of options, and may not have any survivors. So the humans race out with exploratory probes and manned missions. To get a nonzero result, I'm going to suggest they found the things are meant as an ark of some sort. The aliens have been watching [When Worlds Collide](https://en.wikipedia.org/wiki/When_Worlds_Collide), perhaps. So when the first probe does its flyby, it sees a barren moonscape relieved by a fertile river valley, or a hollow sphere full of Nazis, or some other thing suggesting atmosphere and arable land. The rest is just a matter of building ships - lots of ships. According to [StackExchange](https://space.stackexchange.com/questions/55064/cost-per-launch-to-iss-starliner-vs-crew-dragon) the cost of an ISS launch is \$55 million an astronaut. Mass production cuts that, but flying to an orbiting planetoid needs more distance, and there's some equipment to lug. So let's say \$50 million per person. The US Federal Reserve [estimates \$168 trillion in assets](https://www.federalreserve.gov/releases/z1/dataviz/z1/balance_sheet/table/). Assuming 1/3 of these available assets (\$50 trillion) is spent during an exodus, minus 50% for wars with all the other would-be exoduses (we won't count those assets either), we get oh, half a million astronauts. In order to sell this idea to the wealthy and powerful, who control most of those assets, we'll assume that (1) all the astronauts are drawn from their class, (2) the wealthy who don't get to go get clear title to all property, ideas, naming rights, and people left on Earth (who knows, it might survive and they can laugh at the runaways), and (3) a major tech mogul gets to implant microchips to agonize any potential rebels among the slave population. As no one would seriously criticize a program to give away wealth to the very rich during a national emergency (see also [1](https://en.wikipedia.org/wiki/Emergency_Economic_Stabilization_Act_of_2008), [2](https://en.wikipedia.org/wiki/Paycheck_Protection_Program)), the course is settled. The larger bulk of the evacuees will go to the larger and perhaps safer of the planetoids, with a smaller group as a backup on the other. Maybe 400,000 settle along Musk Canyon on Thiel, and 100,000 in Putin Crater on Bezos. This count is for the number evacuated, not the number surviving. The fighting among these best of the best of us for toilets, servitor robots, and frozen slave embryos will be colossal. [Answer] Frameshift (but you're not going to like it): A high tech society (and it has to stay high tech to maintain it's facilities) has a large minimum population requirement due to the fact that people and equipment doesn't come in fractions. You're going to need a lot of specialists and you're going to need backups (what happens when your only widget frobber walks in front of a bus before anyone is trained to take over?) There's no way we are building a self-sustaining offworld habitat of that size in time. However, you're talking capture in Earth orbit. Something of that size can't aerocapture, the only option is gravity capture by Luna--and note that this must be very gentle even in comparison to normal gravity captures or Luna ends up ejected. The approach velocity has to be very low--but the objects are carrying at a minimum 12.32 km/sec. That has to be shed in other slingshot maneuvers--and note that slingshot maneuvers are very sensitive to the initial approach. This needs multiple slingshots, to hit the last one correctly the previous one needs to be even more precise. (Note that NASA has rockets on craft that will be playing planetary billiards, they can adjust for an imperfect slingshot.) The velocity change required to disrupt this chain of events is minuscule if done early enough. Instead of a hopeless evacuation the world should be looking to hammer the moons as hard as they can. (And note the corollary to the high precision required--we simply do not have the ability to determine where they are that precisely in the first place. If they're on such a deadly trajectory we don't know it.) ]
[Question] [ Let's be using your typical centaur: half man, half horse. Due to the nature of their legs, they can't ride animals in the way that humans do. Horse legs just aren't really made to do that. My question is, what kind of animal could I use or create for them to be able to ride, and how would they mount and ride it? It has to be at least semi-comfortable for the taurs, and be able to carry a heavy load over long distances. EDIT: The technology in this world is pretty much dark ages technology. [Answer] Use Chariots Others have suggested carts but I will go one step further and suggest chariots. Chariots only have two wheels so they can handle terrain that carts can't. They can be designed to fit just one centaur (with a cart, the centaur(s) would be knocked around a lot) and have firm railings to grab on it (like the ones made for humans have). Or they could fit 2+ centaurs and/or baggage. They can be pulled by one or two (some pictures I'm seeing show up to 4) horses, other centaurs, oxen, etc. It makes perfect sense to me that even someone who is strong and healthy and built for speed and distance would need a break from traveling, or might need technology to help out for a great journey. [![enter image description here](https://i.stack.imgur.com/SU8jF.png)](https://i.stack.imgur.com/SU8jF.png) Edited to add: I'm seeing many pictures of 2-wheeled chariots that hold 2 people and have enough length to carry a centaur. It appears the wheels go back a bit more. Here's one real life example (I assume the centaur's horse body is smaller than these huge draft horses): [![https://en.wikipedia.org/wiki/Chariot#/media/File:Biga._Festa_do_esquecemento._Xinzo_de_Limia,_Ourense,_Galicia.jpg](https://i.stack.imgur.com/kZiGB.png)](https://i.stack.imgur.com/kZiGB.png) By √Ålvaro P√©rez Vilari√±o - Flickr: Biga, [CC BY-SA 2.0](https://creativecommons.org/licenses/by-sa/2.0 "Creative Commons Attribution-Share Alike 2.0"), [Link](https://commons.wikimedia.org/w/index.php?curid=19814849) And while I don't know the size of the centaurs, here's a picture of the original Greek horses that used to pull actual chariots. One would fit nicely into the chariot in the photograph. [![enter image description here](https://i.stack.imgur.com/Oy1jH.jpg)](https://i.stack.imgur.com/Oy1jH.jpg) (from: <https://news.nationalgeographic.com/2016/09/skyros-ponies-horses-rare-breed/>) [Answer] Since we're considering centaurs I feel free to invent a creature. 1. Let's start with this charming little guy. I give you... the Texas Horned Lizard ([Source](https://www.biologicaldiversity.org/species/reptiles/flat-tailed_horned_lizard/natural_history.html)). [![enter image description here](https://i.stack.imgur.com/B2d49.png)](https://i.stack.imgur.com/B2d49.png) 2. Lizards can really haul the mail. They're sleek, fast, good jumpers, and notice almost everything around them. That charming little tyke is a bit small for our purposes, so let's modify him a bit. * He needs to be the better part of 7 meters nose-to-tail. * He needs to carry a bit of weight — 675 Kg worth of centaur plus whatever is reasonable for them to carry with them. Let's give him two extra feet (6 legs). * His broad back is a great starting point, but let's provide a bit of an evolutionary convenience. Rather than one spine down the middle, let's give him two spines for strength and flexibility. The result is a hammock in the center of the back that's just right for a centaur to lie down in. And if you really want to amp this up a bit, give him a Frilled Lizard's neck flap. It not only scares the crap out of people, but it provides remarkable protection for the centaur (if a bit of visibility hindrance). ([Source](https://www.mediastorehouse.com/nature-picture-library/june-2018-highlights/frill-neck-lizard-chlamydosaurus-kingii-15315823.html)) Remember, 7 meters long, six legs, that flap would be reasonably naturally armored. [![enter image description here](https://i.stack.imgur.com/NIj0K.png)](https://i.stack.imgur.com/NIj0K.png) I definitely wouldn't want to be the fool facing squad of these beauties. [Answer] The sheer weight of a centaur's body would make travelling 'piggy back' for any appreciable distance very uncomfortable. I suggest a specially-designed sling with leg holes to support the passenger. They could then be supported between two draft horse. 1. High-status ones have centaur servants (or horses). Of course they are capable of walking themselves (apart from during sickness or old age) The carriers work one at each 'corner'. 2. A horse and carriage would work well - again with a specially designed sling. --- [![enter image description here](https://i.stack.imgur.com/V46bv.gif)](https://i.stack.imgur.com/V46bv.gif) [Answer] How about Elaphas maximus, Loxodonta africana, or Loxodonta cyclotis? The centaur could ride up an adjustable ramp to the back of the Elaphus or Loxodonta and then stand or lie down on the back. Or the Elaphus or Loxodonta could get down on all four knees with its stomach on the ground and the centaur could climb onto the back before the Elaphus or Loxondonta stood up. [Answer] Bigger horses Might seem glib, but it‚Äôs the best I‚Äôve got. If your centaurs are relatively small then straddling the back of a large breed (A shire horse of some kind, or a Clydesdale ) that is bred for carrying large loads with. Out. Stopping. Is probably your best bet. They‚Äôre relatively simple to mount if you have some wooden blocks and can be ridden much as a human rides a jet ski (knees tucked up at the sides) to keep the weight distributed nearer their hips and shoulders. As far as speed over distance goes they can plod away for ages without needing to stop. They were bred for it, after all. Presumably your half-horse horse breeders will be even better at breeding for big, strong, fast horses, eventually getting back to something more like medieval era warhorse breeds. Just hope they can get over the weirdness... [Answer] The mythical Roc is a pre-made mythical creature that specifically carries cattle around. If such creatures exist in your world it seems reasonable that centaurs might seek them out to use as "mounts" of a kind, though admittedly upside-down to how we normally think about mounts. Many similar creatures to the Roc also exist that could serve a similar role, such as the Phoenix, Thunderbird or Griffin. You can always make your own of course. [![enter image description here](https://i.stack.imgur.com/Z2mma.jpg)](https://i.stack.imgur.com/Z2mma.jpg) Of course the roc is almost entirely infeasible without magic as we can see here:[What is the maximum size of a flying creature?](https://worldbuilding.stackexchange.com/questions/819/what-is-the-maximum-size-of-a-flying-creature) That being said given that they are a pre-existing magical creature like the centaur and so will be slightly more acceptable due to that fact. While the journey won't be tremendously comfortable for the centaur, the speed of flight will make it shorter and thus more bearable. Much in the way that people are willing to endure the cramped conditions of economy class rather then spend a week going by ferry. A leather (or linen if leather makes centaurs understandably uncomfortable) harness could be employed to make the journey more comfortable. If you want futher story ideas the Roc could follow in the mold Tolkiens Eagles and be sentient creatures that the centaurs must negotiate with in order to obtain the services of. [Answer] ## Killer Whales. Firstly, [canals](https://en.wikipedia.org/wiki/Canal#Ancient_canals) have been around for over 4,000 years being extensivley used for transportation of goods and of precious water: > > In Egypt, canals date back at least to the time of Pepi I Meryre > (reigned 2332‚Äì2283 BC), who ordered a canal built to bypass the > cataract on the Nile near Aswan. > > > So it's not unreasonable to assume that an inteligent and trainable mammal such as a killer whale would have been bred [in captivity and trained](https://en.wikipedia.org/wiki/Captive_killer_whales#Training): > > Whales are trained using a system of reward (called "positive > reinforcement" by trainers) by giving the killer whale food or other > reinforcement when they are successful, and withholding it when they > are not. Secondary reinforcement‚Äîthings not essential to life, > such as play time, tactile rewards and fun games‚Äîcan also be used as > rewards. > > > Are they [big enough](https://en.wikipedia.org/wiki/Killer_whale#Appearance_and_morphology) to be used as a mount? Most assuredly: > > Mass: Male: 3,600 ‚Äì 5,400 kg (Adult), Female: 1,400 ‚Äì 2,700 kg (Adult) > Length: Male: 6 ‚Äì 8 m, Female: 5 ‚Äì 7 m > > > Compare horse sizes: > > 380Kg ..... to 1000Kg (for the very largest breeds) > > > Over time no doubt the ingenuity of the saddlers in your era would have designed a suitable way to mount the animal - but perhaps this would necessitate the removal of the dorsal fin just as the beast reaches it's forth month of life - the permanent mark of ownership/attachment to a master. But there is a trade off, males can be agressive - one solution is [castration](https://kb.rspca.org.au/why-are-many-male-farm-animals-castrated_360.html): > > Male sheep, cattle, goats and pigs are routinely castrated in order to > reduce aggression and subsequent injury. > > > This may result in reduced agression without the need for harsh punishments, but what if not everybody had their mount's temperament soothed in this way - that would make for the most dangerous of encounters - leaving you with the dilemma - to live with an agressive mount in the knowledge it'll be able to hold it's own in a fight? - or to have the beast tamed this way and keep your head down, hoping for no such agressive encounters? [Answer] Dragons. Easy to get on, big volume. Might be hard to hold on without thumbs tho ü§∑‚Äç‚ôÇÔ∏è ]
[Question] [ This question already has answers here: [Would the tropic and arctic climate bands switch if the Earth's axial tilt changed to 60 degrees?](/questions/110254/would-the-tropic-and-arctic-climate-bands-switch-if-the-earths-axial-tilt-chang) (3 answers) Closed 5 years ago. Is it possible for the cold, usually polar region to be around a planet's equator — like a belt rather than on far north and south? If so, what would be the circumstances of an Earth-like planet such that this could happen? [Answer] Remember that altitude is much more efficient than latitude in cooling the local climate. If you had a generally coolish world and highlands around the equator, you could have everything higher than, say, 10,000 feet glaciated. [Answer] There's only one way I can think of to do it, and it's pretty implausible The reason Earth's polar regions are cold are: * It's orbiting around one star, heat comes from only one direction. * It rotates, which means the least amount of heat is applied at the "edges" of the planetary face currently facing the star. * It's axial tilt is kinda straight up-and-down (aka, perpendicular to the oribital plane). The result is that the equator consistently sees the most heat and the poles consistently see the least amount of heat and are thus cold. If the only thing you do is tilt the Earth (change its axial tilt), then the best you can do is flop it "on its side" such that it has a rotation like Uranus (98 degrees, or the axis is basically parallel with the orbital plane). * If the planet is thus tidally-locked (which from a previous question, if I recall it correctly, isn't possible) then the one half of the planet would always see the sun and the other would always be dark. Half the planet hot, the other half cold. * If the planet is not tidally-locked, then the areas of ice-cap cold change over the course of a year. The only way I can think of... A binary star But, let's assume that our Earth-like planet had an axial tilt of 90 degrees, was (probably magically) tidally locked such that one pole always faced the central star, and a second star was outside the orbit of the planet and orbited at such speed that a straight line could always be drawn through the planet between the stars... Yup, I'm stretching credulity, but bear with me... Then you have the ability for the ice belt you're looking for. You should probably expect people to suspend their disbelief with this one. But, we were happy to suspend our disbelief during Star Wars when a massive-enough-to-affect-solar-system-orbits Death Star rolled in to blow away Alderan... so you're good! [Answer] larry niven came up with a way, spin the planet faster so it flattens out just a bit, the higher altitude at the equator will make it cold enough to form glaciers. Works even better is the planet spins 90 degrees or so to the orbital plane. Note there may be a significant change in gravity depending on how flat you make it. [Answer] Are you allowed to have a very large number of small (artificial?) equatorial satellites, causing sufficiently frequent eclipses? (Or, if they are somewhat further away, dimming the light). There could be a number of excuses for those, of course, but that was not the present question. [Answer] How much geo-engineering are you willing your planet/system to suffer? There's a fictional planet where the highly-powered non-corporeal aliens are keeping all the continents in a continental equatorial ring so they can maximize certain plant growth. Using volcanism, and heat distribution I bet you could heat up the seas in such a world, maybe even put some land-mass at the poles. Do it on a cold world, and/or raise up the equatorial belt for altitude cooling, and you could get some of your effects. Also, as @agaitaarino's answer suggests, you could screen off the sunlight to the equator using artificial means. For example you could have a lot of debris in the ecliptic plane (going thru a nebula?) - however it would normally bounce out of there, so you'd need some mechanism that is picking off the edges (automatic huge lasers that decimate everything outside of the plane?). Artificial shades would be more efficient, but would probably need more active management. These are of course non-natural solutions, and likely require active management, although possibly on a long-term time scale. You could make a ring-world/non-planet structure, as well. The central point of this world is also going to have a lot of work to be done. If you don't have a central equatorial landmass to dump all of your ice on, the ocean currents are going to need some serious thought. Weather patterns in either case. Temperate clime with huge sunlight shifts is going to be problematic for your ecosystem, especially with an ice/cold barrier preventing easy seasonal migration. [Answer] Here are two possibilities for frozen equator and warm poles. Possibility one: One way is for the planet to spin rabidly and have a very oblate shape when molten and cool down and solidify while still oblate. The planet's rotation can later be slowed down to the desired rate by factors like the gravity of a moon or companion planet after the planet is solidified. There are limits to how oblate a solid planet can be. But might be possible for a planet to be oblate enough for the planets various lawyers to be lot thinner at the poles than at the equator. As we all know, the deeper a mine or other excavation goes, the hotter it gets from the internal heat of the Earth. If your planet is several times more oblate that the Earth, the difference in equatorial and polar radius will make the polar regions significantly closer to the source of the planet's internal heat. The internal heat of the Earth comes about equally from primordial heat, heat left over from the formation of the Earth about 4,600,000,000 years ago, and radioactive decay. The cooling of Earth's primordial heat has slowed down over billions of years, and so Earth's primordial heat emission was greater in earlier ages. As radioactive isotopes in the crust and mantle decay, they produce less and less heat over time. Thus radioactive decay produced much more internal heat in earlier ages. So a planet's surface will receive more heat from inside while it is younger than when it is older. But I don't think you can make your planet much younger than Earth to have more heat from the interior if you want it to have interesting features like a breathable atmosphere, advanced multi celled lifeforms on land, and/or intelligent native life, because all those appeared relatively recently on Earth on the geological time scale. So you could increase the heat flow from the interior by making your planet somewhat more massive than Earth, giving it more primordial heat, and giving it a heavier original concentration of radioactive isotopes. And you can add a third internal heat source that is not very important or Earth but could be very important on your world. Tidal heating. The best way to get significant tidal heating on your planet would be to make it a giant natural satellite or moon of a gas giant planet. The gas giant planet would have to orbit in the habitable zone around the star, or possibly a bit farther out if the tidal heating is enough to compensate for the lower amount of sunlight received. According to this article: <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/>[1](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/) A moon can orbit too close to a giant planet and get heated up so much by tidal heating that the moon will be too hot, and/or, like Io, will have too much volcanic activity, to be habitable. But if a moon orbits too far from the gas giant planet it will not be bound tightly enough to the planet and it can easily be perturbed by other astronomical objects and escape from orbit around the planet. Thus a gas giant will have a habitable zone in which a very large and potentially habitable moon can orbit and not be overheated and not be lost into space. And the size of that habitable zone can be calculated from the mass of the gas giant planet. The length of the moon's monthly orbit around the planet can be calculated from the mass of the planet and the distance the moon orbits around the planet. A potentially habitable giant moon of a gas giant planet will have its rotation period slowed down to match its orbital period. It will keep one side always facing the planet and one side always facing away from the planet. but it will continue to rotate relative to its sun with a day equal in length to the orbital period around the planet. Of course if the habitable moon has a day that is too long it will heat up too much in daylight and cool down too much in darkness, so you will want the moon to have a day that is not too long, which means that its orbital period around the gas giant planet must not be too long. And you will want the planetary sized moon to receive less heat and light from its sun than Earth does, so the moon would not be habitable except for the extra heat coming from the interior due to intense tidal heating. If the planet sized moon is significantly more oblate than Earth, the polar regions, closer to the core, might receive enough heat from inside to have liquid water, while the equatorial regions might been too cold for liquid water. Thus water from the polar regions would evaporate and be carried by winds to the equatorial regions were with would become ice in the glaciers. Many of the glaciers would flow to the north and the south and would melt when they reached warm enough regions, thus returning water to the warm polar regions. And possibly your planet/moon could have a tall equatorial ridge like Iapetus. Glaciers could form on the equatorial ridge and flow down it to warmer latitudes melt. And to make one of the low polar regions even lower, perhaps millions of years ago a giant asteroid struck one of the polar regions and exploded and formed a vast concentric impact basin centered near that pole. And perhaps material ejected from that impact came raining down on the equator to form the equatorial ridge. This would make one of the polar regions lower and maybe warmer than the other. Possibility two: If a hypothetical planet rotates around an axis that is perpendicular to the plane of the planet's orbit around its star, the planet has an axial tilt or obliquity of zero degrees. If, on the other hand, the hypothetical planet rotates around an axis that is in the plane of the planet's orbit around the star, the planet would have an axial tilt of 90 degrees. The real planets in our solar system have axial tilts varying from 0.03 degrees (Mercury) to 82.23 degrees (Uranus). That means that during part of the Uranian year (84.0205 Earth years long) the north pole of Uranus will be pointed toward the sun and in constant light for years at a time and the south pole of Uranus will be pointed away from the Sun and in constant darkness for years at a time. And then, 42.01025 Earth years later, the south pole of Uranus will be pointed toward the sun and in constant light for years at a time and the north pole of Uranus will be pointed away from the Sun and in constant darkness for years at a time. And halfway between those two periods, 21.005125 Earth years before and after, Uranus would be positioned where sunlight would fall on it almost parallel to the equator of Uranus. Since Uranus has a day about 0.71833 Earth days long, every region of the planet would have about 8.619 hours of light followed by about 8.619 hours of darkness. So if your planet has an axial tilt close to 90 degrees then there will be periods during its year when one pole is pointed at its star and has constant light. Thus the pole will heat up very much. The farther away from the pole one got, the greater the angle that the sunlight would be coming down at the less it would heat the air and the ground. At the planet's equator the sunlight would be coming down almost parallel to the ground and wouldn't heat up the ground much. And the other side of the planet would be in constant darkness and would get colder and colder. Water vapor from the pole facing the star would flow in winds toward the opposite side of the planet, and would freeze out at the equator and/or the opposite side the planet. And half a planetary year later, the other pole would be in constant light and heat up. The glaciers forming there would melt and some of the water vapor would be carried away by winds and freeze out on the equator and on the side now in darkness. And halfway in between those two extremes, the planet would get starlight coming almost straight down at the equator which would warm up a lot, with much of the ice evaporating, and coming down at a great slant at the poles which would not be heated up much. The planet would have short days and nights everywhere. And in the intermediate periods the planet would have intermediate climate. It is possible (but not certain) that the poles would heat up enough when they pointed at the star to have tropical weather during their warm seasons, but the equator would never get warm enough to completely melt the glaciers there. Thus the equatorial glaciers would get bigger and bigger until the equatorial regions were covered in ice sheets. The disadvantage of this is that the polar regions would have cold seasons so they both would have rather temperate climates, not tropical, with alternating winters and summers, instead of constant summer. One way to minimize this, as well as reduce unbearable temperature extremes, would be to make the planet have a very short year due to a small orbit close to a dim star. Thus the polar regions, especially if they have plenty of water that retains heat, might not cool off too much between "summers". I would guesstimate that it would be good for your planet to have a year shorter than 84.0205 Earth days (2,016.492 hours) but longer than 84.0205 hours (3.5008541 Earth days). Wikipedia's list of potentially habitable exoplanets list planets with years ranging from 4.05 Earth days to 384.8 Earth days, with 10 planets having years in the the range I guessed at. <https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets>[2](https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets) ]
[Question] [ Most (quadruped) dragons are depicted as having two wings sprouting from their back, consisting of a limb structure draped with a leathery membrane as the way to create lift and fly, somewhat resembling bat wings. I'm looking for a material to replace the membrane with, with some better qualities than a thin, fragile piece of skin. I'm excluding feathers and somewhat stiffer wings like pterosaurs seem to have had (according to this question: [Bats With Pterosaur Wings](https://worldbuilding.stackexchange.com/questions/82444/bats-with-pterosaur-wings)). The properties I'm looking for: * Tough/hard, tear-resistant material * Capable of creating and sustaining lift * (Largely) chemically inert To be clear, they fly by flapping the wings / soaring on currents, as birds do.The dragons in this case are small (somewhat bigger than a big dog / size of a medium-sized pony). They do not weigh much to be able to fly (how much is still open for debate). Does such a material exist? Would it be plausible to appear naturally in a creature? What speed would a dragon as depicted be able to achieve with wings consisting of this material? [Answer] Keratin Fingernails, hair, horn and feathers are all made of keratin. Keratin is a versatile protein which serves in many different vertebrate appendages. A model I think would be cool for your dragon wings is [baleen](http://us.whales.org/faqs/facts-about-whales-and-dolphins/what-is-baleen). [![baleen closeup](https://i.stack.imgur.com/J9xfT.jpg)](https://i.stack.imgur.com/J9xfT.jpg) from <http://www.naturespic.com/NewZealand/image.asp?id=4805> Imagine fingernail stuff but as long rigid strips arranged to form a slightly flexible and hairy plate. This would be a fine wing. Like a fingernail there is not a blood supply. The tips of the wings would get worn, frayed and weatherbeaten. They would be continuously regenerated from the base (like a fingernail, and I think like baleen). Baleen plates can be big! [![right whale with huge baleen plates](https://i.stack.imgur.com/tyZZu.jpg)](https://i.stack.imgur.com/tyZZu.jpg) <http://www.alamy.com/stock-photo-skeleton-of-right-whale-showing-massive-head-and-baleen-french-national-104156574.html> [Answer] How about Kevlar? This is an organic compound and could conceivably be produced in an animal equipped with the right biochemistry. Another component that might be used instead of, or as well as Kevlar, is spider silk or a material similar to it. Spider silk is elastic and very strong although normally encountered in very fine filaments that are easily broken; it can be spun and made into much larger and more resilient objects. For instance this very rare rug made entirely out of Madagascan golden orb spider silk: [![spider rug](https://i.stack.imgur.com/6W7yr.jpg)](https://i.stack.imgur.com/6W7yr.jpg) <https://www.wired.com/2009/09/spider-silk/> Update it would seem that some spider silk is even stronger than kevlar <https://www.wired.com/2010/09/super-strong-spider-silk/> The size of some of the webs has to be seen to be believed. Made me feel rather quesy walking under one of the webs at dusk even though it was high up between trees. [![Golden orb spider](https://i.stack.imgur.com/xcvnt.jpg)](https://i.stack.imgur.com/xcvnt.jpg) [Answer] Spider web silk. Per pound stronger than steel. Don't know how it compares to kevlar, but the idea of a dragons being artificial creatures with genes from spiders has a certain appeal... Even better idea would be graphene. Would be super light weight, almost invisible. [Answer] [Cartilage.](https://en.wikipedia.org/wiki/Cartilage) It is a tough and elastic material. If you wish for a stronger structure it can be arranged in scales or in semi-fixed folds, held together by or glued to thin t-section bones. You will need to wrap it under a membrane and a lubricating layer to prevent unnecessary wear and friction. For faster repairs, you could let the chondrocytes move semi-freely in the lubricating layer. They will cluster around wounds and help rebuild the damaged areas. Also, no blood vessels are needed for maintenance, unless, as mentioned above, you wish for a quicker healing. ]
[Question] [ On "Earth" species that are higher up the food chain tend to have more advanced brains. I won't tell everyone what they already know, but just for illustration: chimps are capable of making tools and sign language and more while horses can't. Yet clearly, [Dressage](https://en.wikipedia.org/wiki/Dressage) is no small feat, and still reflects how they have the common mammalian trait of learning from experience. What I want to do is decouple this relationship between food chain locus and "cleverness." I hesitate to define a yardstick because I think common sense is best here, but if we must, let's define "cleverness" as: * Problem solving ability * Pattern recognition * Plan development We could argue some herbivores have this kind of intelligence, but it's not at the same degree as some predators. Also not really interested in cognitive/sensory intelligence, like superior depth perception. Purely for illustration: imagine a deer-like creature digging a pitfall around the area it wishes to graze in, so that when pursued it would know where to jump and leave the predator to fall into the trap. ## Question What kind of natural / evolutionary forces need to be in play in order for my world to obtain an equilibrium such that herbivores possess superior intelligence to carnivores? [Answer] Intelligence requires energy Can you believe this? Humans use their intelligence to conclude that vegetarianism is a better lifestyle! This despite the fact that the only reason intelligence evolved in the first place is because a carnivorous diet provided the energy necessary to power that evolution and higher brain functions. Though some (probably all) would argue with me, the reason vegetarianism works is because our protein-and-fat-derived intelligence allows us to (and this is important) craft the development, growth, harvest, and processing of plant matter to sustain our divine ascendancy to reason. But that lovely fact exposes a perfectly reasonable answer to your question... If plants evolved to provide the source energy needed to evolve intelligence, then the only reason herbivores wouldn't evolve human-like sapience (hah...) would be the unlucky chance encounter with a large enough group of carnivores that they got wiped out. So, what does your evolution need? * A world filled with high-energy, high-fat, high-protein plants (or a combination of plants in a large enough area to provide the aggregate effect). * Time (in the form of safety). And one other thing... * The need for problem solving. Nature vs. Nurture You've heard the old adage of nature vs. nurture? Am I really bad because I was born that way, or was I taught to be bad? In short, never underestimate the effect of your environment on the development of intelligence. Bring too much adversity and you wipe out your developing intelligentes herbivorus. Bring too little adversity and intelligence never develops. So, you also need... * Just the right amount of adversity over that long period of time. Which is one of the many reasons why Darwin marketed the process as the survival of the fittest. Overcome enough obstacles while enjoying the right kind of diet and a plant will develop intelligence. [![enter image description here](https://i.stack.imgur.com/A2HZV.jpg)](https://i.stack.imgur.com/A2HZV.jpg) Image courtesy the [Farscape Encyclopedia Project](https://farscape.fandom.com/wiki/Zotoh_Zhaan) [Answer] I think you have oversimplified the picture, and lost a lot of important things in the process. First of all, there is a fundamental difference between carnivore and herbivores when it comes to their feeding: one of the two doesn't have to worry about its candidate meal running away. However it doesn't mean that all carnivores are always more intelligent than all the herbivores at any moment, nor that herbivores can be always and at any moment more intelligent than all carnivores. A carnivore who cannot outsmart an herbivore in any situation will soon be a starved carnivore and its species will be extinct, and an herbivore which is constantly "dumber" than the carnivore trying to feed on it will also soon be dead and extinct. Episodes play a big role in the daily struggle between carnivores and herbivores: a snapping twig can make the difference between a miss and a lunch when a carnivore is trying to ambush an herbivore, same as a dead end on an escape route. If you really want to push the boundaries on the herbivore side, you can try with something that make also the plants react to being fed upon and enact some countermeasures. Like it happens with some acacia trees, which start producing tannin when giraffes eat their leaves: the giraffe have learned the mechanism and cope with it by feeding going toward the wind, so that they can find unalerted trees. This means that they can recognize a pattern (when I eat leaves, they become bitter. The trees upwind from my feeding place are not bitter, those downwind are), make a plan and solve a problem (when I feed I should move upwind to find non bitter leaves) However, for what I have said above, herbivores will never be consistently smarter than carnivores. [Answer] Intelligence is (theoretically) a major survival advantage. That's the reason it is evolutionary selected for. For carnivores, this is easy to explain: being more intelligent makes you able to hunt better and defend yourself better. You can craft weapons, nets, traps, and dwellings. All of these things increase your chance to survive long enough to procreate. For herbivores, the same story is true. Being intelligent gives you access to more food and better protection from predators. If you can use tools, you can access the insides of hard nuts or better dig up roots. If you can make traps, weapons, and dwellings, you can better defend yourself. We see aspects of this all throughout nature. Look at beaver lodges as a huge example. Also, while not technically an herbivore (aquatic life is it's own beast), sea otters use rocks to break open shellfish. The big question here is not "how can herbivores develop intelligence?" but rather "how can dumb carnivores be viable?" There are a couple options here, and you can use any combination of them. 1. There is only one very intelligent herbivore species. While the carnivores will eat those herbivores if they get the chance, they tend to go for easier game (i.e. the less smart herbivores) for their main sustenance. See, for example, crocodiles in Florida who occasionally eat humans but mostly eat other stuff. 2. The carnivores have substantial physical advantages over the herbivores they hunt, making it a competition of brains vs brawn. See, for example, chimps and jungle cats (a natural predator of the very smart chimps). 3. There are a lot of the herbivores relative to the carnivores. Thus, to the herbivores, the carnivores cause occasional population loss rather than an existential threat. This is generally true of herbivore to carnivore population ratios in general, but intelligence would probably skew it a bit heavier towards the herbivores because they can band together. See, for example, herd animals on a savanna and lions. Other answers have some discussion of the nutritional requirements to support intelligence. While intelligence is nutritionally expensive ([humans use about 20% to 25% of their calories on their brain](https://www.livescience.com/burn-calories-brain.html)), it also can solve for the problems it creates. Humans are able to sustain their massive brains on vegan diets. The key things here are heavy consumption of legumes and the use of cooking to improve the nutritional value of food. If you want to have an environment that emphasizes this, have lots of protein and fat rich plants that have a high intelligence requirement to access. Walnuts are a great example; lots of protein and fat, but you need to be able to use basic tools to get at the edible part. [Answer] # Instead of trying to buff herbivores, nerf the carnivores Imagine a world of trash. Maybe a precursor civilization has polluted the world, maybe it's an experiment, maybe it's just an accident that nobody bother to clean up, you tell me. --- 1. Nutritional energy for cognition This world have a lot of fertilizer runoff or equivalent on the surface, allow the plants to grow strong and nutritious, allowing herbivores can have enough energy to sustain some form of intelligence. Since this is artificial fertilizer, it can even have some exotic mineral (Ca, Zn, etc.) that rarely exists in nature yet our brains need. --- 2. Preventing carnivores from developing intelligence first Unfortunately, this world is also hit with a lot of heavy metal contamination, which means anything carnivorous will eventually accumulate too much toxin, and die off. The higher on the food chain we go, the quicker the accumulation. Intelligence is not all that powerful on its own, without support from a longer lifespan to accumulate knowledge, an overlap in generations to facilitate education, social aptitude to share knowledge, etc. Throw a spanner into one, and the rate of developing cognition is slowed down, maybe enough for herbivores to catch up. --- 3. A need for problem solving ability that do not involve other living beings Again, we do not want to involve any other species in this drive for cognition, seeing as this would require that animal to be equal to the herbivores in intelligence. So you could add that not only the planet is covered in pollution, its climate pattern is also damaged to the point that it has extremely volatile and unpredictable weather. Emphasis on unpredictable, so your herbivores cannot just select for an instinctive behavior that will protect it once, and keep it to the end of time. Also emphasis on volatile, and maybe widespread as well, so no amount of toughness, or overwhelming number will save them on its own. That way, the weather will select for animals that have: * Problem solving ability: Each type of natural disaster will require different countermeasures. For example, forest fire require you to get to ground, and run to water, while flood need you to get to high ground instead. Since the weather is extreme and unpredictable, animals that cannot solve problems quickly cannot thrive. * Pattern recognition: When long-term prediction of random disaster is not feasible, the ability to quickly notice and understand the beginning stages of a disaster is highly valued. Each second you realize the danger is a second you can prepare for it. * Plan development: While the long-term prediction of weather is not allowed here, long-term preparation for it is not. Building nests underground near water to avoid fire, have escape routes to avoid flood, food storage in case of flash freeze, etc., having the correct counter on hand allow this herbivore to thrive. --- 4. Remember to provide the little details Make sure that the manipulators evolved on your herbivores are something that can continue evolving, like a limb, tentacle, or elephant trunks, have more than just one of them, give them social instinct to group together and exchange resources and ideas. So long as an herbivore gets to be a civilization first, it will both give drive for more intelligence, while out-competing any other sentient-wannabe. Which will end up with an herbivore become the dominant intelligent species of your world. (If you are asking for how herbivores on average get to be smarter than carnivores, I got nothing there) ... Until the herbivores meet up with whoever created such a world, and get a practical demonstration of the benefits of eating meat [Answer] ## An arid planet could have this effect A planet mostly covered in deserts means that herbivores are constricted to watering holes, river banks, and other really obvious places for predators to go to hunt for them. These fertile zones are so small and narrow that hiding from predators means going inland where there is no food or water, and only risking the journey back to these oasises when absolutely necessary. This makes being a predator very easy. Hang out by the water, and eventually the food will have no choice but to come to you, so intelligence is not super important. Ambush predators are generally not as smart as predators that have to roam a larger territory looking for animals to eat. However, intelligent herbivores don't need to get play this eternal game of "eat and run". Intelligence means you can learn to make in inhospitable landscapes more survivable. Your smartest herbivores will learn to dig wells and irrigation to create safe zones out side of the predator rich natural water zones... and if predators start to show up, they abandon these artificial oasises which soon fall into disrepair and become dead zones again. Other herbivores may learn to survive by being able to remember where dozens of individual shrubs are just barely hanging on over an area of several square miles; so they need exceptional memories, spatial awareness, and enough self awareness to take good care of these plants so that they don't eat themselves out of long term survival. Some herbivores will need live off of raiding the store houses of the really smart agricultural herbivores meaning they will need to be smart enough to avoid the traps and plans of the really smart herbivores who are trying to keep them out. Lastly, intelligent creatures do not tolerate intelligent competition. If your herbivores win the smarts race to weapons and tool use, then they will kill off any predatorial creatures who begin to become intelligent enough to represent a real threat. [Answer] Adversity drives the intelligence, and it needs to be changing adversity. If it's just a constant environmental adversity, the species evolves to the point of surviving the environment, and then stops. So with predators, both sides of the equation get more and more complex. Eventually, one side or the other evolves true intelligence and wins. They either control or wipe out the other at that point. The herbivores will need to have a reason to evolve some way to manipulate their environment with fine control. Maybe some of your plants take a delicate touch to eat without getting poisoned by thorns or symbiotic protective species. Most likely, it will be a herd species, since that seems to provide the optimal survival strategy for herbivores before intelligence. As they get closer to true intelligence, their communication becomes more complex, they start spending more time in abstract thinking to control the predators, etc. High calorie food helps with the larger brain as mentioned in several answers, but also with providing a surplus to allow leisure time to develop ideas. Now you have a species already evolved to work together cooperatively, that has the ability to use tools, communicates to exchange ideas, and have gained the problem solving intelligence to take the fight to the predators. They are well on the way to civilization. Niven's Pierson's Puppeteers eventually wiped out all of the predators on their planet, but I don't think that would be the best way to go. Without predators, the idea of war and fighting could easily fall by the wayside, and then the species can be enslaved by the first carnivore species that comes along. I would think that some of these herbivores, having learned to hunt predators, will have enjoyed it. Free time and bigger brains means more time to explore ideas they wouldn't have before, so hunting may become a sport that keeps predators around. Then your species never forgets that there could be OTHER carnivores out there. You may even end up with herbivorous Klingons. ]
[Question] [ So, floating islands are a pretty common trope at least in the media I've consumed, and one thing that sort of stands out - oftentimes, they're meant to be a reveal to a larger world (Either as part of a secret group the protagonists come to seek help from, or more exposition on a situation, or as part of a larger escalation of the conflict of the story.), and the people living on the non-floating ground of Earth aren't usually aware of the floating island, except in legends that they don't know about them until then. At best, the Grounded People believe the existence of the island is a legend, a myth even, even though the Sky People have been around for ages, often millennia. This however, poses a problem - for this Floating Island is neither at sea on its own (Which still leads to the issue of sailors noticing it when sailing), nor likely at International Space Station levels of height out sight (Or applying the "Move very quickly across the sky" orbital trick to avoiding immediate notice). So, how do they manage to hide themselves from Grounded People when people should just be able to look up at the sky and see it, or potentially notice it through a telescope? Especially on a clear day/night, where cloud cover isn't an option? ## Is there a way to hide an floating island from below for any climate situation, and is there an upper limit on when that solution would fail in terms of the technology level of Grounded People? (I'm presuming it would fail when airplanes and/or spaceship related technologies being up, but I'd like to at least hide the island through the Medieval era tech if possible.). Bonus if it's a passive way to hide the island itself, and not require active powering of technology to keep it hidden. [Answer] ## The Island is kept aloft by a powerplant that produces steam Any natural phenomenon that produces cloud cover to hide your island will always encounter weather situations where the clouds dissipate from time to time... that is, unless the clouds are not natural. A nuclear isotope with a long enough of a half life, and in abundant enough of quantity could turn your whole island into a giant natural reactor that could last for thousands of years. However, nuclear power means boiling vast quantiles of water, which means lots of steam, which means the island is perpetually producing its own cloud cover. So, the same power source keeping you in the sky is also keeping you hidden. Because the reactor boils so much water, the sky people need to occasionally lower a massive pipe down into an ocean, lake, or river to replenish their water supply; otherwise, the system could be mostly passive. Very rarely, someone might notice this pipe, but the sky people don't want the land dwellers to know about them so they are generally careful to only lower it when they are somewhere very remote so the occasional sighting would be by so few people that it would be normally disregarded as a tall tail. But it does happen from time to time. In fact, one time someone even climbed up the pipe, saying he had found a magic bean stalk, but since the bean stalk was gone by the time he could show anyone, no one really believed his story. > > Those aren't clouds, it's steam! > > > ~ Migo (Smallfoot) > > > [![enter image description here](https://i.stack.imgur.com/RlQA8.png)](https://i.stack.imgur.com/RlQA8.png) While not a 100% passive hiding system, this would allow you to stay hidden even after the development of early aircraft since the clouds could envelope the whole island. It would take the discovery of radar to conclusively prove its existence. ### For a more passive low tech approach Make the island look like a cloud. I don't just mean color, I mean shape and texture too. One of the things that make clouds look like clouds is the their shape. They have gaps and funny outcroppings too them. Luckily so do some islands. Many islands, have very cloud like shapes to them; so, if you give your island enough of that shape, then you have half your job done for you. The hard part then becomes, the surface. Just painting the bottom of an island white wont's give it that aerie translucent refractive look of a cloud, but luckily there are some solid materials that have very cloudy appearances. If the entire bottom of your island were encrusted in a thick layer of mostly transparent white crystals, then you could get branches of crystals sticking out the side that create that wispy see-through look you at the edge of clouds, and any side lighting from the sun will shine through it giving it more or less the same reflective/refractive colors of other clouds. [![enter image description here](https://i.stack.imgur.com/5oJW1.jpg)](https://i.stack.imgur.com/5oJW1.jpg) Because the light is so diffused, you do not need exact samplings of adjacent sky to project the way you do with active camo so you can take refracted light from the edges and bend it downward such that no actual light from the top is actually needed to make the structure seem fully saturated with light. [![enter image description here](https://i.stack.imgur.com/YL8PU.jpg)](https://i.stack.imgur.com/YL8PU.jpg) ### For best results, mix these two methods together The crystalline bottom will look like just more cloud if it pokes out through the bottom, and the steam clouds will ensure you have an amorphous outer edge so that someone watching your cloud over time does not notice it moving too rigidly. [Answer] Psychological warfare. The culture below has been "seeded" and social-engineered into believing that seeing dark objects above is a certain sign of death (Maybe some ancient beasts circled the land once above) and thus, one desperatly ignores the shadow and thing above, praying silently that the evil eye may fall upon somebody else. [Answer] What is needed is active camouflage: Either by simply increasing the light emitted by the base of the island with lighting From around 1:13: <https://www.youtube.com/watch?v=aIceh3Bk0Cc&t=1s> Or adaptive camouflage where the colour of the background is detected and projected below <https://www.youtube.com/watch?v=KL_KdmSTSNA> Close up they don’t work that well but at long range of a mile or two it should work well enough [Answer] ## High altitude lowers water's boiling point Many depictions of floating islands have some measure of water on them, be it a lake, or some sort of self-sustaining water system via rain and waterfalls and rivers, etc. This suggests the island has some sort of way to create its own clouds, mainly by way of easier evaporation, due to higher altitudes lowering the boiling point of water and making it easier for the sun to turn the water into vapor, and keep itself hidden in its mists/clouds for a little bit even when the rest of the sky is relatively cloudless. [High altitude boiling](https://en.wikipedia.org/wiki/High-altitude_cooking) Depending on the geography of the island it might also 'capture' passing clouds and drag them along with itself for extra cloud cover. A minor problem comes when someone observes this collection of water vapor for a long enough time that parts of the island peeks through the cloud. This could lead to legends of it cropping up, with those who didn't or can't see what the others saw for that brief moment usually shrugging believing they're a little crazy for most of history. A bigger problem comes the moment people have recording technology like cameras, or any form of aerial mobility at all with something as simple as a hot air balloon. Then they'll either be able to gather proof or take others with them to confirm the floating island's existence. The shadows this island will cast down below will also be a problem, and unless during a heavy rainstorm the darkness it'll make will certainly make people curious. I don't know if your island has any special properties(other than floating), but I suggest that wherever it goes there is a rather heavy rainstorm going on either naturally or somehow created by the island. [Answer] It is far enough away to look like a celestial body It can be tricky, thanks to the low altitude compared to the moon or any other celestial body. Yet if the telescopes aren't good enough, it is very well possible a high floating island is regarded as a strange celestial body. If the island is high enough it can already be difficult to spot. Planes are big, but quickly diminish in size and detail the higher they go. An island can be much bigger and still hide the fact it has life on it. With strange world views fueled by religion or ignorance (flat Earth), it isn't a stretch that the floating island is just a strangely behaving celestial body. Maybe it's represented in folklore, or a diety, or mabe the island is sort of predictable (doesn't move fast), so it can be an extra navigational point for people taking note where it is in the sky periodically. The fact is, it can be as mysterious and unknown as the moon itself. People will try to explain it, but sky people might be one made up or with a grain of truth story. One in many. That way sky people living on a floating island is as likely a possibility as the rest. Or unlikely... who would you believe? A person who says it's an object like the moon. You can see some detail, but never enough. Or do you believe your religious leader, telling it's your deity, a great power of unknown that rules the lower skies. Or some scientist with a telescope telling everyone there's people living on a floating rock up there. The premise is so ridiculous that the others seem more likely. [Answer] It looks like a bird. [![bird](https://i.stack.imgur.com/oC4bD.jpg)](https://i.stack.imgur.com/oC4bD.jpg) [source](https://jooinn.com/bird-85.html) Up close it would look like a really really big bird. But it is not up close. It is higher than the clouds and there is nothing next to it to estimate scale. Viewers assume it is a bird flying high up. Really it is a colossal fake bird flying very high up. [Answer] Hide it in plain sight. It's a huge rock in the sky, so what. Its been in the sky for a millennia as far as people know. Sure you might find rumors' of the sky people or just as easily the legend of the dragon's living on dragon island. You would have ancient history of countless myths and legends of the great rock spanning for a millennia and none of them confirmed, no changes ever seen for all that time. Everyone knows it could never be reached as it's more than a 5kM high, no tower can even be conceived that high by man in modern times. [Answer] It could be visible but in a place that’s uninhabited, like above the ocean or floating in/above a valley in some kind of himalayan-style mountain range. Somewhat similar to Shangrila. Those few people who discover it might (a) stay, because it’s convenient or too remote to get back, (b) die on the harsh way back, or (c) return home just spread the same old legend of a place that nobody else believes to exist [Answer] Perhaps like Death in Pratchetts' books. People don't see it because there is no such thing as a floating island. Maybe children will see it and tell their parents, they will always be scolded and the adults will turn back to their works on the field... [Answer] [Counterillumination](https://en.wikipedia.org/wiki/Counter-illumination) and an island bottom painted white, with long cloth streamers, will make the island resemble a cloud. When possible, of course, hide among other clouds. Depending on altitude (but how would they breath?), some sort of cloud seeding might be possible to get clouds where ordinarily there wouldn't be. This is, coincidentally, the method adopted by the mythic Tempestari pirates in the ninth century - they also had machines that ground water, dust and grain and produced a thick fog. They were said to live in the fabled land of Magonia (which possibly comes from magia, or 'Magic'). Their ships were believed to be the cause of hail and thunder, or so the Bishop [Agobardus of Lugdunum](https://en.wikipedia.org/wiki/Agobard) reports in his Liber contra insulsam vulgi opinionem de grandine et tonitruis ("Book against the silly urban legend on hail and thunders"). [Answer] If it hangs out off the coast of a continent, hovering about 2km high, ~25km off the coast. Combine this with various other methods others have mentioned, such as produce steam and have a crystal bottom, it would be too distant for people to say "that aint no cloud!" Unless some sailors spend excessive time out to sea under it. With it being ~25km away from the closest observer and with a crystal structure, at sunrise or sunset (depending which coast your off, it could shine in the sunlight to look like a celestial object. However, this would wreak havoc to early astronomy and will be quickly discovered upon the invention of the telescope. [Answer] Try again, supposing it's impossible to hide This deserves a second answer attempt. On my first answer, I tried to hide the thing from view. That is not going to work, because the inhabitants of the floating island have no technological means to hide their village/city/country size world from view, when it floats in the atmosphere.. to allow the medieval inhabitants of the floating island to breath, it should be below 7km altitude anyway, and avoid high mountain tops. There is no way this rock would not be visible in clear sky.. or occluding stars at night. It will always blow its cover, for people somewhere on the planet. You would need to project a cosmic hologram on the bottom, to make it transparent. Dream on.. Medieval people Medieval people depended on agriculture. The inhabitants of the floating island will need all their water for growing crops. Fertilization is questionable, the amount of grounds is limited. Living up there will be a harsh life, inhabitants will need to find ways to survive. When hiding is/was a priority, they are on a wrong plan. They can't hide. Maybe they'll attempt to hide.. but the can't assert if it actually works. From the planet's surface, their island will be visible as a dark blob in the sky, sometimes occluded by clouds. It can be visible, yet remain unnoticed Suppose visibility (alone) is no issue. People on the planet are medieval too, they won't know there are people up there. On top of the platform, people are living.. but on the planet, technology does not allow a flyover to prove that. So the people on the planet are unaware of the inhabitants living above, on the floating island. For them, the floating island is a rock in the sky. Like the moon, but not round. For centuries, the platform could be regarded as "just another celestial body in the sky" but much lower altitude, floating in the atmosphere rather than being "another hole punched in the celestial sphere", like medieval people believed. They could assign an astrological meaning to it, but they would actually know nothing. The island is safe. Science, when it develops on the planet, will want to find an explanation Drawing a parallel with earth scientific development, you could say in late-medieval times, the presence of this floating rock would turn into a scientific question: what is this rock in the sky ? how can it float ? why is it the only one we see ? how high up is it really ? Questions would arise.. but we're talking Galileo Galilei and Keppler. In all centuries before them, it would not matter what this rock in the sky meant. It was a celestial body floating low, just like a planet, or a small moon. People would get used to seeing it, until they don't notice it anymore. [Answer] Go somewhere without too many humans A floating rock over a dense rainforest makes it too much of a pain to investigate, but still gives you regular rain. For best results, sit on plateau above a jungle, to be as inconvenient as possible to reach. [Answer] So, are we really going that way, huh? You could be statisfied with "it was always there" or "make steam under it so ppl will think it's a cloud" ( =? ), but we know you aren't. This is not an island of farmers or murlocks, there is an evil archwizzard up there and he WILL have the island cloaked eventually. So what'd he do? Depending on whether there is magic in the world or not, he would create an optical illusion below the island to cloak it from viewers below. How? Well, not by mounting a big rack of mirrors below it. You'd want to have a flat, convex lense below the island that will break the light in a way that the sky besides the island is visible. How do you achieve this? [![enter image description here](https://i.stack.imgur.com/oWAtl.png)](https://i.stack.imgur.com/oWAtl.png) You can place a flat body of water under the island , either by magic or with glass, the science way. you then need to make a convex lens on top of that, so it wouldn't be too bad if these where one and the same body. The light needs to be broken in a way that directs the light from the side of the island to the bottom, so to speak. This all serves like a gigantic alchemist's bauble and you basically already know this from physics class ^^ This way you can be a sneaky boii (don't edit this) [Answer] Make your own cloud. Heaps of cotton wool - or something like it. Create a faux-cloud and stick it to the bottom of the island. If it's high enough up then it should be relatively hard to detect until at least the invention of telescopes, and probably longer if it sticks to existing cloud cover where possible. [Answer] Put it over the dark part of the moon On first sight, painting the bottom black will do.. however.. in daylight, your platform would cast a shadow on earth's surface, anyone would see the platform. At night, your floating platform will hide stars behind it. These stars will move 6 degrees per hour, in respect to an observer on Earth surface. You'd need a running animation on the bottom, inconceivable with medieval technology. Now suppose the platform would have an near-polar orbit, always accurately placing itself between Earth and the Moon, a few degrees off. The platform's bottom should be painted black, it won't be visible. It needs to be high up, or it would be seen from different angles next to the moon. Also, I haven't solved the 'full moon' situation. So maybe... they would have to paint it over, every month ? With medieval technology, this question is very difficult.. [Answer] It naturally/magically sails on Clouds. As in, it cannot free-fly, it instead "floats" in clouds like a boat on water. Inherently therefore, it cannot be seen because there is always a cloud underneath it to block the view! In order to ensure that a heavy rainstorm doesn't result in the island crashing to earth catastrophically, the mages of your floating island have cast a spell to call clouds towards the island at all times (or perhaps it's an innate part of the magic that causes the island to levitate in the first place). [Answer] Camouflage Paint The most prestigious job in the Cloud People’s society is being a bottom painter. It’s a constant operation, usually performed under the cover of night, but they keep the bottom of the floating islands painted to conceal them. They’re oblivious to the fact that the ground dwellers may have discovered the painting operation millennia ago, because the ground dwellers humor the Cloud People. ]
[Question] [ The superhero has magically increased strength but also magically increased weight so that he can utilize his strength effectively and stay planted. The drawback is he has to make sure things can hold this increased weight. If he was running through an apartment complex and jumping about while fighting someone, would standard floors (built to safety regulations, assuming it's not rotten or poorly put together) generally be able to take this amount of weight or would he fall through a floor? Floors can take a lot more than this weight in furniture but it's a static load. At what level do dynamic loads become an issue for standard flooring? [Answer] In short: In a wooden floor built up to modern building codes a 750 kg hero is unlikely to break the beams, but he may cause some damage. In long: There are two problems with loads on floors and other structures: overall resistance of the floor and punctual resistance. That is, in a wooden flooring, that the beams don't break (making the whole flooring fall down) and that the plank where the hero is resting his foot don't break. Since most (all?) building codes all over the world have rules to check for those two problems, I am going to take my numbers from [the Spanish one](https://www.codigotecnico.org/pdf/Documentos/SE/DBSE-AE.pdf) (point 3.1.1, page 9) which must be quite similar to the numbers anywhere else. I'm using here kg/m2 although the code is in kN/m2 (1 kN/m2 = 100 kg/m2) for ease of comparison with a 750 kg hero. Overall strength of floor and beams isn't going to be a big problem because floors are checked for an uniform load ranging from 200 kg/m2 for dwellings and hotel rooms to 500 kg/m2 for supermarkets. If the room isn't full, a 750 kg load is equivalent of the design load of a few square meters. Therefore, a 750 kg hero is only going to be a problem if the room is already full, or if at least the part of the room over the same beam where the hero is, is already loaded. For example, the hero should avoid attending a party in an hotel suit already packed with people. The point load may be more tricky because structures are checked against loads of 200 to 700 kg on a 5 cm x 5 cm square. Then, in a wooden flooring, his weight might exceed the design load of individual planks. The best advice here would be to walk carefully trying to rest his feet only over the beams. That piece of advice could be hard to follow during a fight, but planks falling and the hero clinging to the beams might make great shoots for an action movie. In addition to that, there is a relieving fact: strength is not the only condition that leads structure design, and very often the most stringent rule is against excessive bending. Therefore, very often beams can hold several times the design load without breaking, in spite of a large deflection that could be aesthetically unpleasant (or even frightening) and may cause cracks on non structural elements. And a last cave-at: the OP says that the hero is fighting someone. If "someone" is a team of 750 kg villains or heavier, the situation may be trickier but using villains for load testing could be advisable and could lead to an interesting plot. [Answer] Depends on the size of his feet Load stresses are often mitigated by weight distribution. 3/4 of a ton being constantly imparted by the surface area of the average human foot, really it's half a foot on impact for when you think of how people generally walk and run, is going to be hard to ask the floors to keep intact. Doubly true for a 'running' load, which would be equal to simply dropping that weight on the floor repeatedly, which is very likely to break through, assuming things like fleshy softness and bone brittleness are to be ignored. If he's going to be traversing floors I'd suggest he trains himself to both adjust how he puts his feet down as well as adjust his method of imparting his weight in similar manner as to how one would be careful across ice that would be fine to walk across but not run. I'd also suggest he get himself some shoes that increases the surface area of his feet, in a similar way as what snowshoes would do. [Answer] It is likely Ok At least in the US, 750 kg should be easily supportable. Building code requires support of at least 40 pounds per square foot, so even a small 100 sq ft room is designed to carry at least 4000 lbs (1,818 kg) of load. So unless a room already has heavy load in it, 750 kg is perfectly fine. What is making the outcome iffy is that his load is not static - he's running and probably jumping. His feet are working like sledgehammers wrapped in shoes. The floor as a whole can support his static weight, but if it is momentarily applied at a weak spot, for example a joist below his feet has a hidden crack in the middle - then yes, this joist may fail, although this would not cause the entire floor to collapse. P.S. The stress on the floor can be classified as "highly localized", as limited to individual foot, or just the its heel or ball, and "locally distributed", as spread into the area as large as 10 sq ft/1 m2. My "Likely Ok" verdict was based on the latter, "locally distributed" stress estimates. The way the floors are constructed, the former (highly localized) stress strength has a much higher tolerance - it's always the supporting joists, rather than subfloor (typically plywood) that are failing first. To damage the subfloor, you need to hit it with something hard, like unwrapped sledgehammer, or damage its support (joists). [Answer] It's possible Maybe a not so scientific answer, but we can assume much from current footwear. High heels. From several research sources I gather that a 50kg woman in high heels is exerting more pressure per square centimetre than a 4000kg elephant on all it's feet. Quick math tells us that each heel is then exerting more force than 1000kg on one elephants foot. The foot is between 40 to 50cm in diameter. The pressure of a high heel is about 15 times higher per square meter than an elephants foot. The feet of your guy might be closer to the surface area of high heels, but in all cases are still several times bigger than a high heel. The difference in weight is coincidentally 15 times the weight of the woman (the weight of a 50kg woman vs 750 of your protagonist).That would mean your protagonists feet always exert less force per square meter than high heels. As I've seen woman who, despite their claims, are more than 50kg run in impressively high heels without breaking floors, I would say it's entirely feasible to fight on 'normal' floors for your protagonist. As for the carrying weight of carrying beams, I think it won't be much of a problem. In my experience with both parties and moving (heavy) equipment, it is relatively easy to exceed 750kg in small areas. Of course this is temporarily much higher when pushing off, but as the floors would spread the weight over multiple beams it's unlikely to be a big factor overall for these carrying beams. [Answer] I think the answer is that he would have to be very careful. The point of failure is going to be the plywood subfloor that you then put carpet, tile, or other flooring over. Typical flooring is constructed of 2x8 or 2x10 joists spaced 16" apart with 3/4" or less plywood on top. The plywood distributes the load to the joists which distribute the load to columns or walls. The problem is that your hero is a highly localized phenomenon. A piano may way 800 pounds but it has 4 legs and distributes its weight in four different places on the floor so each one has only 200 pounds. I found a couple of interesting links. [This one](https://applianceanalysts.com/plywood-weight-capacity/) has a strength calculator which gives 960 pounds as the max total load for 1" plywood floor with 16" spacing. Typical 3/4" plywood gives only 384 pounds as the max. Then there's [this study](https://nvlpubs.nist.gov/nistpubs/Legacy/BSS/nbsbuildingscience53.pdf) on concentrated loads. Not a single flooring system tested would support your hero standing on one foot, except in a couple of tests where the joists were spaced at 6". Most of the tests had failure at less than 1/2 the weight of your hero. But your hero is not going to be a static load. He is going to be 'running and jumping'. An Olympic sprinter can push off the ground with a force of 1000 pounds (average people are about 500-600 pounds). If your hero is running, he will be temporarily applying 5,000 pounds of force on the flooring. If he steps between the joists his foot will go right through the floor. ]
[Question] [ I have searched around the site and seen several population-related questions, but not one that is getting at what I'm specifically wondering (or that is at least explaining it in a way that my mathematically challenged brain can get around). Apologies if I missed one though. So I have a kingdom with a population of approximately a million people in 24,000 sq miles. The kingdom has existed for approximately 1600 years. This kingdom is probably analogous, roughly, to medieval Europe in the 1400s. I've worked out that there are 159 noble families within this population. (using this site and tweaking things here and there: <http://donjon.bin.sh/fantasy/demographics/>) Due to various events, the nobility is predominately killed off, save for a single child from each family (some families without children and some mishaps meaning not every family), leaving 113 children of the noble class left. The population is basically human for all intents and purposes, but there is magic-type element at play that manifests in one member of this noble class at a time and does not pass directly from parent to child-- it just appears to randomly select a new host within the group when the previous has died. I am trying to figure out if: 159 noble families is enough that there wouldn't be significant risk of inbreeding through the 1600 year history (safe to assume the number of noble families may fluctuate throughout the centuries, but 159 is the number prior to them being massacred). And how many individuals would be a part of these 159 families, realistically. Again, overall population is around 1 million. ETA: second part question removed because it's a moot point and I just blanked on an obvious point in my story. haha Thanks! [Answer] If we think of the nobles as an isolated (by choice) population, then what we need to look at is the human Minimum Viable Population (MVP). From [this question](https://worldbuilding.stackexchange.com/questions/3/what-is-the-minimum-human-population-necessary-for-a-sustainable-colony) about a sustainable space colony, we get [this source](https://www.newscientist.com/article/dn1936-magic-number-for-space-pioneers-calculated/?ignored=irrelevant#.VBiC_XtDLwo) which says the number is 160, or maybe 80. > > The “magic number” of people needed to create a viable population for multi-generational space travel has been calculated by researchers. It is about the size of a small village – 160. But with some social engineering it might even be possible to halve this to 80. > > > [This source](https://arxiv.org/abs/1806.03856) argues that 98 is fine, if we're only talking about genetic diversity and assume no other catastrophe. > > The survival of a genetically healthy multi-generational crew is of a prime concern when dealing with space travel. It has been shown that determining a realistic population size is tricky as many parameters (such as infertility, inbreeding, sudden deaths, accidents or random events) come into play. To evaluate the impact of those parameters, Monte Carlo simulations are among the best methods since they allow testing of all possible scenarios and determine, by numerous iterations, which are the most likely. This is why we use the Monte Carlo code HERITAGE to estimate the minimal crew for a multi-generational space travel towards Proxima Centauri b. By allowing the crew to evolve under a list of adaptive social engineering principles (namely yearly evaluations of the vessel population, offspring restrictions and breeding constraints), we show in this paper that it is possible to create and maintain a healthy population virtually indefinitely. A initial amount of 25 breeding pairs of settlers drives the mission towards extinction in 50 +/- 15% of cases if we completely forbid inbreeding. Under the set of parameters described in this publication, we find that a minimum crew of 98 people is necessary ensure a 100% success rate for a 6300-year space travel towards the closest telluric exoplanet known so far. > > > So your population of 113 might just be viable if they breed very carefully, assuming they have a near 50-50 male to female split. And of course, they aren't on a spaceship; their genetic isolation is voluntary. So they still have the option to marry the occasional maid or whatever and improve the situation. And regarding the pre-massacre period, if ~100 individuals can be made to work with careful planning, then 159 families should be able to get on just fine as long as they avoid obvious inbreeding. [Answer] Nonpaternity saves the day. Consider the Duke. He is a jerk. He is rough and mean, and prefers the company of prostitutes over the Duchess, who does not really know what she is doing in bed. A large part of that is lack of enthusiasm on her part - the Duchess does not like the Duke, their marriage having been arranged by their family. The Duchess does like her coachman, who is attentive and kind. The Duchess bears an heir! He looks a lot like the Duchess. There is not genetic testing. The Duke is satisfied that his heir is a healthy baby boy and does not give the matter a lot more thought. The coachman remains attentive and kind. He teaches the young marquess how to ride, and hunt, and how to not be a jerk. [Answer] Not necessarily a full answer, but worth considering: many of the "horror stories" result from the historical example of [the Hapsburgs](https://en.wikipedia.org/wiki/House_of_Habsburg). However, that particular situation was exacerbated by the fact that "unfit" genes were kept in the pool by dint of the people possessing them being Hapsburgs, even if they would otherwise have died childless in an unregulated scenario, causing a build-up of recessive defects. Once these were in the main line of inheritance, it escalated in a "snowball effect" (i.e. at least one parent was almost guaranteed to carry the "bad genes"). If Magic is a factor here, it can correct for that simply by excluding these cases from consideration for inheriting the "Family Magic". This does not eliminate the risks of a small gene-pool, but it does help to eliminate the political power of genetically-weak lines, and ensure that at least one parent doesn't carry the "bad genes" (And, occasionally, that obscure branch-family who were having to stoop to marrying commoners suddenly becomes the new Main Line when their child manifest the Magic) [Answer] While the answer based on space travel by Harabeck is excellent, your scenerio has more in common with a [population bottleneck](https://en.wikipedia.org/wiki/Population_bottleneck) because there is no need to maintain the population limit of 168 past the event which kills off most family members. The population of nobility will naturally begin to grow again afterwards. Population bottlenecks permanently alter the genetic diversity of a population. To quote the Wikipedia article > > The chances of inbreeding and genetic homogeneity can increase, possibly leading to inbreeding depression. Smaller population size can also cause deleterious mutations to accumulate. > > > However, they can also select for genes that help the population survive the disaster which triggers the bottleneck. For example, a previous bottleneck event might explain why the nobility has magic. As to the size of a human population which can survive a bottleneck event, a study suggests that [pre-1492 North Americans were all descendants of 70 individuals](https://journals.plos.org/plosbiology/article/file?type=printable&id=10.1371/journal.pbio.0030193) [Answer] The previous answers pointed out that, with the initial number of mostly unrelated individuals you are starting out with, that long term viability is plausible. I would like to point out that, depending on what 'magic' can do, you can turn plausible into a certainty. With technology (genetic testing), it's easy to detect when two particular individuals are unsafe to breed (by comparing genes); the chief problem we moderns would have would be the ethics (and whether two incompatible individuals in love would actually abide by our pronouncements). Now, you don't have technology, you have magic. Magic could plausibly do what technology does (even if it's not spelled out); just have the couples undergo a magical ceremony by the magical patriarch/priest/wizard to see if the pairing is 'blessed'. Of course, if you (for story purposes) want to have severe inbreeding problems, you can still have this magical ceremony, but just have it have the opposite effect; blessing those couples that actually do share recessive genes... ]
[Question] [ Can radiation block all wireless communications? My idea is that heavy meteorite storms are spreading radioactive dust around the atmosphere. I know that traces of radioactive elements can survive entering the atmosphere. And it seems some types of radiation can affect some radio signals. Though there are also 2 problems with this idea. First, can enough radioactive elements enter the atmosphere to have the effect, I am happy to allow new undiscovered types of radiation(or elements) if theoretically possible. Secondly would any type of radiation even theoretically, be able to disrupt all known radio and wireless data bandwidths? [Answer] Since you revised your question, let me try to address the radiation issue in more depth: No, you can't block all wireless communications with radiation. EM interference is what happens when you overlap a communications frequency with the same frequency but different pattern. To jam a signal, you need to match the frequency with a higher energy interference. To block a range of frequencies you need to send an interference wave for each frequency in the range at small enough of increments to disallow a tolerance for transmitting a signal in the inbetween jamming patterns. This means that wide-spectrum jamming requires WAY more power than any individual signal you are trying to jam. Now you need to consider that there are both AM and FM signals meaning that even if you broad spectrum the FM bands, AM might still be immune because you'd have to match their amplitudes instead of their frequencies meaning you need a whole second spectrum of jamming signals. Then you need to consider wire-communications still actually cover most of the developed world; so, to having a meaningful effect, you need to jam them too. To jam those you'd need to bombard them with a sustained EM radiation strong enough to physically push the electrons out of the copper wiring. If this is a natural event, this kind of full spectrum EM radiation won't stop at low energy waves. You'll probably have microwaves, IR waves, gamma rays, etc. When you add all of these forces up, you are looking at something that is so energetic that you'll basically microwave all life out of existence pretty darn quickly. Imagine instead the following scenario for a dystopian communications blackout: Communications companies continue to merge until there is just one global communications company. Let's call them MegaComm. There are a few companies near the end that refuse to sell, so MegaComm just buys up the suppliers that these communication companies rely on forcing them out of business anyway. People start protesting this monopoly, but since they control all communications, these people are censored and politicians are bombarded by enough lobbyists and campaign funding that nothing happens to stop them. Guided by maximizing profits, this company makes 3 very logical business choices after securing their monopoly status. * The first is to stop worrying about quality and just focus on hiring the cheapest people they can find to run their infrastructure. Because they have monopoly power, they don't have to worry about making people happy, just as long as they sort-of fulfill their contractual requirements. * The second is to utilize all those vendors they purchased to be able to exclusively supply all their own networking hardware. Within a decade, every industrial, residential, and commercial network is running off of a unified chip-set designed by MegaComm to eliminate all those pesky compatibility issues the old internet used to run into. This makes maintaining their network way easier and cheaper. Also makes pushing firmware updates super easy so you don't have to worry about hackers messing with your unstandardized data points that someone forgot to patch. * The third is to run everything they do off of a highly distributed and redundant cloud platform backed by blockchain protection. Investors love all the fancy buzzwords and agree this is the way to go. Now, MegaComm's board of directors are feeling awfully proud of themselves. They are wealthy beyond measure, everything is going great... but then, someone somewhere half way down the chain of command decides to fire a bunch of over priced senior engineers, in favor of a new office located in Sri Lanka that will save the company millions of dollars a year! Another great business choice I must say. These new employees don't know anything about cyber security; so, a few months latter, a hacker is poking around in MegaComm's network and finds a vulnerability in their update service. Now this hacker being fed up with MegaComm's bad customer service decides to teach them a lesson by pushing an overclock virus through the update service. With-in an hour, routers modems, cell towers, and even satellites all around the world begin to catch fire and burn up. MegaComm scrambles to restore their last firmware update so they can try to push a fix, but with communications down and the virus already installed on nearly every piece of network technology in the world, their distributed cloud platform has torn all of their data into 1000s of little pieces and spread it all over the world with no way of putting the pieces back together. As data-hubs go down, people are cut off with no way of knowing their stuff is about to overheat so everyone just sits around desperately trying to call MegaComm to find out why their internet is down while all there stuff continues to burn out. A few hours later, ever piece of telecommunications hardware is a brick, and no one knows how to put it back together. The hacker scratches his head in disbelief at MegaComm's incompetence. [Answer] Knocking out all satellites would do some serious damage, destroying navigation and much communications. Underground/international fiber optics are hardly an easy target: they're considered critical infrastructure and are generally both protected and redundant; in vulnerable spots they are often also actively guarded. Their main point of vulnerability is where they pass under the ocean and can be attacked by trawlers. LONG metal (copper) communication wires are far more vulnerable to EMP damage than shorter ones, at least if the EMP itself is large. They can and have been damaged by solar flares, though nowadays are rather better protected from this. Radiation won't do much significant to disrupt wireless comms, but what would is constant electrical activity in the atmosphere. This would also give you your EMPs. A whole lot of charged dust in the atmosphere would do this, and the charge could come from radioactivity maybe? Wherever it comes from, you want charged particles causing lots of lightning. Some serious EMPs to damage unprotected wired electronics would go some way to trashing things: I'm somewhat skeptical if even nuclear EMPs could do significant damage to non-wired electronics like cellphones. You'd have to have power density equivalent to a lightning strike every few square meters, applied over the entire planet to destroy enough stuff I think - but since you want social collapse without destroying most electronics, that would work. So, you will destroy communication, and harm long-distance travel, but you will also hit power generation and manufacture: I would argue these are also needed for decent societal collapse, or the broken systems can just be repaired, and damaged areas of the network would be routed around. Without power, comms, manufacture, or travel, you stand a chance of believable social collapse; food will stop getting delivered, cash machines and bank systems will stop working, news and instructions will not get distributed, so localized riots will break out, escalating as distant fires become visible through the lightning storm. Police and the military will try to keep order, but without good comms, they will be hampered, and if they act heavy-handed will likely just inflame the population into rebelling harder. [Answer] TL;DR: no. "all wireless communications" is a very, very broad category, and to disrupt all of them might well involve rendering the environment so hostile that there might not be any people around to communicate. So. Radiation, as provided by radioactive decay, is not a very good way of disrupting communications. A decent amount of radiation, enough to be hazardous to living things, can disrupt or permanently damage semiconductors, but you could put the clever bits of a radio in a shielded environment and have your antenna on the end of a cable and you'd probably be good to go. You can disrupt [lower-frequency radio signals](https://en.wikipedia.org/wiki/Skywave) (like, under 30MHz) by disrupting the ionosphere, and you can do that with various kinds of astronomical upset in the sun. It'll need to be serious and ongoing, as shortwave radios can be built very simply and cheaply that can communicate around the world, albeit with low bandwidth compared to what we're used to these days. After that though, things start getting tricky. VHF radio is line-of-sight, but you can bounce it off things like planes, satellites [or even the moon](https://en.wikipedia.org/wiki/Earth%E2%80%93Moon%E2%80%93Earth_communication) if you really wanted to. Your hypothetical meteor showers? Might make long distance VHF communication [easier](https://en.wikipedia.org/wiki/Meteor_burst_communications)! UHF and microwave transmissions can be [scattered off the troposphere](https://en.wikipedia.org/wiki/Tropospheric_scatter) allowing point-to-point communication across fairly substantial distances... this was how a lot of long distance communication to inconvenient places was done back before satellite communications became cheap and easy. You don't even have to use radio if you don't want to... [free space optical networking](https://en.wikipedia.org/wiki/Free-space_optical_communication) is a thing, and whilst it is only line-of-sight, there's plenty of scope for the tech to scale up nicely. Optical networking isn't going to be vulnerable to electrical interference in the atmosphere. --- So what can you do? Well, if you're happy for the disruption to be relatively short, you could arrange for a nuclear war. Lots of [high-altitude EMP](https://en.wikipedia.org/wiki/Nuclear_electromagnetic_pulse) will be extremely bad for modern communications infrastructure, and strikes at certain places and cities will seriously disrupt wired communication too. Nukes aren't the only way to do that, but they are pretty good at it. Something more along the lines of a natural disaster would be another [Carrington Event](https://en.wikipedia.org/wiki/Solar_storm_of_1859) which would take out satellites and earthbound power grids though optic fibres and various kinds of electrical infrastructure would be basically unaffected. A serious meteorite shower would effectively disrupt communications by smashing everything up. As a natural disaster counterpart to a Carrington event, you might be able to handwave the two as having the same origin. If you want the disruption to be widespread, long-lasting and affect multiple technologies you're basically going to need some kind of technology to do it for you. Souls in the Great Machine was a book which had a post-apocalyptic society without electricity or radio as a result of orbital microwave weapon platforms which would smite any detected EM sources on the earth's surface. There are plenty of other ideas that could have the same effect, and be of human or alien origin as you prefer. That's probably the best direction to look in. [Answer] It wouldn't be so much that they would "block" transmissions, as introduce so much additional background noise across a wide range of RF bands as to make long distance radio communication with conventional equipment or sustainable signal strengths impractical. Whether that's something that could realistically occur without also coming along with an amount of ionising radiation rapidly lethal to all life on Earth is another matter. There aren't that many radioactive materials that directly emit RF (really, that's more in the realm of the fluorescent), anything that they might cause would be more from the emission of higher energy waves and particles that would then be absorbed by other matter that re-emitted some of that as lower-energy photons. Though at least some of those original emissions would still be picked up by radio equipment and that alone might interfere with a wide range of frequencies, and simply interfering with the reception side is of course enough to cause disruption. [Answer] Radio wave and Wireless (wifi) are both a type of low frequency Electro Magnetic Radiation. Wireless, Radio, Microwaves, sun light and all light even glowing plutonium are giving off photons. Sometimes this is the consequence of the atomic structure being unstable as in the case of plutonium or it can be a process of using EMF form a [magnatron](https://en.wikipedia.org/wiki/Cavity_magnetron) (the device that makes microwaves in your kitchen microwave, for example) to excite the energy level of electrons to relies microwave photons. An easy at home demonstration is try having in a cell phone conversation in-front of your microwave while it is running. The signal coming from the cell towers should be interrupted by the photons coming off the microwave, resulting in poor resection. [![EM spectrum with examples](https://i.stack.imgur.com/aNHS2.png)](https://i.stack.imgur.com/aNHS2.png) To answer you question, that could theoretically work. Maybe have a type of material that emits photos that are of the same weave length as cell towers. Without cell towers, you would be down cell (Internet) assisted GPS; most modern telecommunications; and the social result of people not being able to text, facebook, and twitter would create a very panicked situation. Very offer meteors hit the surface of the earth and don't brake up entirely; maybe as delivery mechanism. The amount of area that would be effected by this jamming radiation would not be very great. Just like the effects of a microwave on a cellphone call, you would have to blanket the entire planet in this material to disable all telecommunications. Mind you, just like you can have bad cell reception or not get wifi in the further rooms of your house, since this material would be giving off photons competing with the photons of wifi and cell towers, the material could be shielded against just like microwaves and cell phones can be shielded for. 1. "First, can enough radioactive elements enter the atmosphere to have the effect, I am happy to allow new undiscovered types of radiation(or elements) if theoretically possible." * Not really most meteors are very mall by the time they get to Earth. To the the sort of dispersal you would need something coming from an inorganic process, to keep with realism, like a weapon. * [Either stuff that hits Earth is too big to be burned in the atmosphere on it's way down, in which case it wouldn't contaminate that large an area on earth or you can have a sprinkling of smaller debris in a localized area (creator).](https://en.wikipedia.org/wiki/Meteorite#Meteorite_recovery) 2. "Secondly would any type of radiation even theoretically, be able to disrupt all known radio and wireless data bandwidths?" * Yes, if you have a situation where like with cell towers and wifi the EM is used as a carrier wave for digital information you can block the EM by generating radiation that will compete with the radiation carrier wave. * It works sort of like watering down juice: after it's watered down, the part of the mixture that is juice is less then that which is pure water, so not enough of the juice gets to the, in this case cell phone, for you to get the Internet over wifi or broadband; where juice is the carrier wave. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- Closed 6 years ago. * This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). * 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). [Improve this question](/posts/98222/edit) Is there a reliable and, at least, relatively safe way to keep a person unconscious for a period of at least a year(more would be better)? It doesn't really matter whether the individual is comatose or just "sleeping". I just need a way to keep a person unconscious for a year or more without causing any substantial physical damage to them. I'm not an expert so I don't know if using anesthetics for a long time is dangerous or how to avoid other issues like bedsore and stuff. [Answer] If you have the person completely unconscious, in addition to bedsores you have to feed and water them, change them, etc. A drug strong enough to produce a coma can be strong enough to have you stop breathing, so you need to pay attention to the dose. If the person alters reality with their mind then you might need unconscious. If you just need them out of commission and not paying attention you can have them awake, and on antipsychotic and amnestic drugs. [![old thorazine ad](https://i.stack.imgur.com/O4YYS.jpg)](https://i.stack.imgur.com/O4YYS.jpg) This ad is a little funny because of the waving cane but it is close to the truth. The drugs in thorazine class make inputs from the outside world less strong and bothersome, and make people disinclined to do anything. If someone has schizophrenia and is afflicted by sensory inputs that are too much or cannot be ignored, these drugs can allow a normal life. They can be used to settle down someone who is drunk or on acid so they are disinclined to act on their impulses. They can make a person with Alzheimers be inclined to sit and nap instead of try to cook or leave the house. Such drugs are tools, and people have mixed feelings about some of their uses. But they work. They also are great for hiccups for some reason. Combined with a benzodiazepine (the best known is Valium but the date rape drugs are in this class; when you have them on board you do not lay down memories as well) you can snow your person and keep them snowed. But the person will shift weight to avoid a bedsore, eat if you put food in front of them, walk from here to there with encouragement. Also a person in this situation makes a better narrative device because they are still present, and capable of (reduced) agency. [Answer] An [induced coma](https://en.wikipedia.org/wiki/Induced_coma) can be used for weeks or months at a time. Like most medical procedures, it has side effects, but they are considered less dangerous than any alternative in some cases. "Substantial physical damage" may be in the eye of the beholder. [Answer] ## No. Spending a year unconscious will damage you. There isn't any way around that. Here is a description of spending 70 days mostly inactive: <https://www.vice.com/en_us/article/jma83d/nasa-patient-8179-200> If you spend a year that way it will be worse. There are a number of other concerns like bedsores or the risk associated with whatever you're using to induce unconsciousness, but "without causing any substantial physical damage" is just off the table. [Answer] Regarding whether using anesthetics for a long time is dangerous, of course it is. Using anesthetics at all is dangerous. Unconsciousness, even on the order of minutes is possibly (and even likely) lethal. Mortality due to anesthesia in surgical procedures is presently at 0.4/100,000 in Europe (used to be 8/1,000 in the 1960s). So, yes, you can die just like this, even with a dedicated person watching your body in super-paranoia mode, only because of anesthetics. Note that when I say "super paranoia mode" this means that persons under anesthesia normally have much better vital parameters than you do in normal life, the anesthesist makes sure of that. Is it possible to hold a person unconscious for a year without serious defects? In principle.... sure. You will need either a PEG tube or intravenous feeding, which works reasonably well nowadays, monitoring, and you will need a clinitron bed and a dedicated nurse at the very least. Also, you will need a physiotherapist visiting daily, and you will have to perform transcutaneous electrostimulation. So... if three thousand or so dollars per day are no problem, then sure, you can do it. Not that I'd recommend it. The solution proposed by @Will is much preferrable due to its cost effectiveness and safety. Doesn't have to be thorazine, there's a couple of drugs that will do well for the task. Dim the light a bit, cage the window, close the door, and you're good to go. [Answer] A person can be put in a hypnotic suggestive state where he is "frozen" and would be appearing to be unconscious for as long as you want. The successful and maintained suggestion is all that is required. Time would not appear to have passed for such a person if that was also suggested. This sort of thing is not possible with all people, though. Psyops projects that looked into the programming of highly suggestible people for subsequent use in assassinations, i.e. exploit the fact that a suggestion can have a very long lasting effect. Derren Browne has a few popular demonstrations of this type of remote control effect over time. One of his demonstration includes a remotely induced state of control that is triggered by a specific stimulus leading to a fake assassination attempt. In another case a participant is rendered unconscious and transported into a completely different part of the world, and yet another is just transported later in time to his astonishment. It is certainly possible. Indian Gurus in caves also reportedly accomplish this by suggestion too, except they work on themselves. [Answer] It's sedation or anesthesia which IS NOT the normal restorative sleep. I have read [this](http://serious-science.org/difference-between-sleep-and-anesthesia-1160) article mentioning the Michael Jackson case. It seems that the sedated people must be allowed to go to a normal sleep from time to time. [Answer] Yeah sure, unless you want the person to still be alive. There is a 2.199% Of the person staying alive. AND a even less chance of all the body parts being able to work. (And, you`ll have pee in your bed) You could try to put them in a freezer. But... you might again,die from hypothermia.. Also, you might die from not having water, as started at: <https://www.scientificamerican.com/article/how-long-can-the-average/> Unless you would like to risk it, don't do it. Why do you even ask.... Locking Door ]
[Question] [ A scientist creates device that allows some degree of communication with the afterlife. The communication is very difficult and the dead can only pass small bits of information on, so there is a lot of we still don't know, but it appears so far that most of the Dead are happy in a peaceful place, much happier than they were on Earth. There are some scientists who claim to have communicated with spirits who are living in the place of extreme suffering but those are only a few and not taken seriously by scientific community or the populace generally. Given this scenario, how do I explain no increase in suicide rates after this device is mass-produced and many people can verify the discovery for themselves? More detailed information: The device has trouble communicating specific words or concepts but can quite reliably communicate ideas such as happiness or pain. The device has trouble picking out a specific spirit to talk to. [Answer] 1) There's so little information coming in from the spirit world that lots of people think it is a hoax, especially since you can't pick a specific spirit. Also, how much do they remember of their former lives? Do they drink from the river Lethe? 2) It hasn't been proven that EVERYONE goes to the afterlife. Notably, if no one who died of suicide is ever heard from, that indicates that suicide interferes with going to this happy place. 3) There's no proof that these are even spirits of those departed, as: > > device has trouble communicating specific words or concepts but can we use quite reliably to communicate ideas such as happiness or pain. > > > [Answer] Your best bet here might be to ask a few of the several billion religious people on Earth why they don't commit suicide. Many people very firmly believe they're heading to an afterlife when this life is done, but suicide isn't particularly common. Here are a few reasons why: 1. In many religions, suicide is considered an unforgivable sin. Well, at least in Catholicism, but I think there are others. (It seems the Catholic church [no longer teaches this](http://www.catholicdigest.com/articles/faith/knowledge/2007/04-01/do-people-who-commit-suicide-go-to-hell), but the idea is definitely real.) 2. Many religions teach that we're on this planet for a purpose, and committing suicide is contrary to that purpose. 3. If there's an eternal afterlife waiting after this one, what difference will a few more decades make? 4. Many religions talk about rewards in the afterlife being commensurate with accomplishments in this life. Who wants to be stuck in the ghetto of heaven for eternity when they could suck it up and try for the Ritz? 5. As long as your friends and family aren't killing themselves left and right, committing suicide will cause them grief, anguish, and hardship. Putting them through this isn't very nice, is it? 6. Just because there are hardships in life doesn't mean everyone is miserable and just waiting for a better place. Lots of people actually enjoy this life and aren't in any particular rush to leave it behind. 7. Of course, not everyone is really sure about the whole afterlife thing, so they're less willing to take the risk. As noted in some other answers and comments, the premises of the OP don't lend to undeniable proof of anything, so the "I'm religious but don't really believe" crowd will still exist. [Answer] Suicides to get to the happy place increase, but regular suicides decrease. People who had been committing suicide to end it all now realize that they're still going to be around afterward. What's the point in that? The net result is that the decrease offsets the increase. So on average, no increase. You can also talk about people on the other side who talk about things that they wish they had done first. Even though they are generally happy, they still have regrets. If all else fails, go with the Christian solution. Suicides don't go to the happy place but to the unhappy place. [Answer] There's not information from the other side to convince most people conclusively that things are better in the afterlife. The basic description of this device and what it communicates suggests it is highly unreliable. As a thought experiment if people had easy access to what life was like in the afterlife, then if everything was hunky-dory people could be convinced that passing over would be a good thing. In which case, suicide might be on the increase. Taking into account the thought experiment as a counterfactual and comparing this with the facts that the situation with your device is so uncertain and definitely not informative, then sensibly people aren't likely to be catching the suicide express. Basically it's ordinary skepticism at work. Also, people do tend to be reluctant to kill themselves. Death might be OK, but dying can be messy and painful. Besides we will go there sooner or later, and later might be a better bet. EDIT: Comments raised issues about veracity and belief. Consideration of those issues raised another possibility entirely. Of course, most major religions will endorse of a 'proven' afterlife and as proof of their faiths. (The inverted commas are there because poor communication to the afterlife suggests there are good reasons to doubt its authenticity.) However, the majority of major religions do not endorse suicide and as a result are quite likely to preach strongly against their adherents from committing suicide. Therefore, the failure for suicide rates to increase is a response to this preaching against suicide by the religious authorities. [Answer] * There is no deep trust in the message coming from after life. They might perceive it as an biased "afterlife advertising", trying to fool people in undertaking a one-way journey. * They might suspect the ratio unhappy/happy is 1000/1 or so, but they keep hearing only the few being in the happy place because the local ruler only allows them to talk. [Answer] The afterlife may be happy, but the process of dying is very unpleasant. Kind of like going to the dentist, without Novocaine. [Answer] \\There are some unusual anomalies with portal use to enter Earth life, including that when Earth's departure portal is activated, the very next destination cycle after Earth is never the Origin dimension. \\ Those within the Origin dimension well understand the mechanism and processes of their common portal use to various numerous destinations, and prepare their portal travelers subconsciously for what to expect on arrival in that dimension (approximate fetal growth and incubation time, birthing method, likely atmosphere at birth, etc.). There is however, a special deviation in portal use in that whenever destination Earth is chosen, they recognize that those people never return to Origin dimension immediately upon departure from Earth. Rarely, people return to Origin dimension after one other dimension cycle, most after several other cycles, and some only after many, many other dimension cycles. There are some who have still not returned. None ever return directly from Earth to Origin after one cycle, and portal usage cannot be tracked until they return to Origin. Because of this and other unusual anomalies seen with Earth destination portal use (usual between-dimension communication is disrupted for people within Earth dimension; it is extremely complex and rarely easily perceived), there is an off-shoot of portal travel study that specializes on this destination. Through the millennia, the portal travel patterns of people who chose Earth destination and eventually returned have been studied extensively. These studies have identified one anomaly where, for some unknown reason, anyone choosing to intentionally activate the departure portal from the Earth dimension prior to Earth dimension's naturally occurring exit-portal activation protocols (death) are those that experience the highest number of additional Earth dimension cycles prior to their return to Origin. For the majority of Origin portal travelers, this is a huge deterrent to dimensional travel, for various reasons, including the fact that most of them do not want to risk being limited to only one dimension for so long, and even possibly for always. Because some very high-value experiences have been reported from the Earth dimension experiences that have not yet been found within any other dimensions, portal specialists have devised a method that seems to have greatly reduced this risk through additional subconscious programming. They are now including additional programming with a very simple basic protocol that embeds at a preeminent level into the Earth life-forms: extremely strong individual survival drive. [Answer] Clearly, the people who try to end their lives sooner so that they can go to this happy place will not end up in the place of happiness, and that is one of the bits of information conveyed by the people in the place of pain, that many of them intentionally tried to shorten their lives (some by suicide) just so that they could get to the happy place sooner. As for how they knew about the happy place, that could be easily explained by a local religion. Note that all suicides causing you to not go to the happy place is completely optional, and you could allow (or choose against allowing) people who commit suicide for some other reason (maybe they just want to end their pain in this life) to still go to the happy place. ]
[Question] [ Hello World Builders, In the world I'm designing, the most advanced nations chose to focus heavily on natural helium (readily available in this world) airships for reasons justified by the world (access to resources), each nation having a war-ready flotilla. I assume a ~1850 tech level for things I don’t explicitly talk about. I have started to sketch a few classes, and as they have been developed with inspiration from boats, I assume, except for gunships, that the primary armament (smoothbore cannons) would be on the sides of the ship. I’m not after utmost accuracy, but I've read some answers and I’m quite puzzled by opinion on cannons. For some, cannons would unbalance too much the airship, and for others, smaller caliber cannons would be ok. My first question is: are cannons viable as an airship’s primary weapon? Secondly, still about armament, I’d like to equip my ships with short-range defense weapons. I’ve thought about weapons like early Gatling guns, but someone made the remark that they would be of no use against airships. Would they be utterly useless against small airships? In the last part, early rocketry plays a big part in warfare transformation in this world and rockets start to be used as an offensive weapon (much inspired by Congreve rockets). I want to have carriers, and I thought that gliders, equipped with small rockets (to gain altitude) and Gatling guns would be a good candidate for carriers, as they could harass enemies. This is by far the most far-fetched element (I’ve found 1914 for earliest carrier-launched raid and early 1920s for the first rocket-powered airplane), but is there a chance that could work ? Even if I studied some number from historical airships, I’m really not savvy enough on physics to assess the plausibility of what I’m suggesting. I’m not looking for 100% physically accurate airships, I just want to avoid the other people instantly finding fatal flaws in my designs. Thank you for taking the time to read this ! :) [Answer] If you actually want this to be scientifically realistic, you've got a load of problems here. If you want it to be rule-of-cool technofantasy, life will be much easier. You've picked a setup where those two styles are a long way apart. You have plentiful helium as a given. OK, that helps, but making a lightweight gasbag that will actually keep helium in is hard. It's a very compact little atom, and it diffuses through substances that will confine air quite effectively. For example, a rubber balloon filled with helium will only remain buoyant for about a day, while one filled with air will hold pressure for more like a week. With 1850 tech, you don't have the kinds of materials that are used for modern airships. Then there's the question of weight and weight lifting. Muzzle-loading cast-iron cannons are really heavy. The [twelve-pounder Napoleon](https://en.wikipedia.org/wiki/Canon_obusier_de_12), for example, used in the American Civil War, weighs 1,200lb, or twice that with its carriage. Your helium has a net lift of about 2lb per cubic yard, so you need 1,200 cubic yards of helium to lift each gun. Without crew, ammunition, the gallery to put them in, and so on. So if you have eight guns per side, that's 20 tons of guns, or about 20,000 cubic yards of helium. That's 40 x 60 x 80 yards, or 120 x 180 x 240 feet of helium, just to lift the guns. Your airship is going to need to be at least as big as the largest ones ever built on Earth. Those were the [Hindenburg](https://en.wikipedia.org/wiki/Hindenburg-class_airship) class, which were built with the most advanced materials of the 1930s. With 1850 tech, you don't have aluminium or magnesium available in quantity, or even decent steel, so your airship structure is going to be iron. That has a much worse strength-to-weight ratio than aluminium, requiring the airship to be even larger to lift the weight. This is not going to work well: there's a reason the first airships weren't built until the 1880s, and the first large ones in the early 1900s. Technology changed at least as much between 1850 and 1900 as between 1966 and today. On the subject of technologies, one that you are missing with 1850s tech is the internal combustion engine. You have steam engines, but they are horribly heavy for the power they develop. Again, the airship gets bigger and bigger. So, while you have the "reality-check" tag on this question, the answer has to be "no, this isn't practical within 1850s technology." [Answer] John Dallman has pointed out the key limitation of airships, which is the vast size needed to lift even relatively small loads. Obviously an airship isn't going to carry a 1200 lb cannon, for example, and based on the sorts of weight limitations, relative speeds between airships and so on, small calibre weapons with relatively flat trajectories will be the ones airship navies will want for direct fire roles, and explosive rounds capable of spraying shrapnel will be a close second when looking at ways to attack enemy airships. Using 1850 era technology, it might be feasible to arm airships with a battery of barrel organ guns like the [Nordenfelt gun](https://infogalactic.com/info/Nordenfelt_gun). Various versions of these weapons were made with barrels of up to 25mm calibre and a ten barrel gun could fire at a cyclic rate of 1000rpm. For airship use, smaller caliber ammunition and/or fewer barrels would provide a powerful, lightweight weapon. The Royal Navy eventually adopted a 4 barrel, 1" version which weighed 203kg, and was considered to have the sort of range and "punch" to be useful in repelling torpedo boats and boarding parties. [![enter image description here](https://i.stack.imgur.com/pywlt.jpg)](https://i.stack.imgur.com/pywlt.jpg) 4 Barrel, 1" Royal Navy Nordenfelt Gun As for your use of gliders, this is similar in concept to the US navy's experiments in the 1930's of using giant airships as "aircraft carriers". The limitation is the same as everything else with an airship, you only have so much available lift, so a "Carrier" will not have as much lift for offensive and defensive weaponry. [![enter image description here](https://i.stack.imgur.com/9w8RF.jpg)](https://i.stack.imgur.com/9w8RF.jpg) [![enter image description here](https://i.stack.imgur.com/26FJZ.jpg)](https://i.stack.imgur.com/26FJZ.jpg) For all its vast size, the USS Macon only carried six very small fighters Trying to combine the various factors in your description, it seems the best way to provide both enough firepower to make an airship a worthwhile weapons platform and incorporate many of the elements you want, we need to combine the gliders with rockets to make an "aero-torpedo". [![enter image description here](https://i.stack.imgur.com/P0QJr.jpg)](https://i.stack.imgur.com/P0QJr.jpg) Hobby rocket glider. This would make a good model for an aero torpedo This provides a light weight, high speed weapon with a relatively flat trajectory (allowing you to shoot at other airships), capable of carrying a reasonably sizeable warhead, so the blast of shrapnel can cause damage even if the aero torpedo misses. This also provides the ship with the means of delivering fire against ground and sea targets; aero torpedoes can be shot at wet navy ships or troops on the ground out of range of most small arms and cannon, and still deliver a useful sized warhead. Rocket powered aero torpedoes fired back at the attacking airship from ground or naval mounts will not have the ability to reach the same altitude, giving the airship a considerable advantage. [Answer] Personally, I would avoid the cannon idea. Cannons were used on ocean going vessels because it could cause them to sink when they took enough damage to their wooden hulls. Causing hull damage to an airship is not the most efficient way to solve the problem. I propose the idea of some of the other early weapons such as ballistae. With sufficient force, this could be much more damaging to an airship than a blunt cannonball. It could be made to penetrate several gas bags and it should fit the technology level that you are aiming for without hand-waving like a rocket would. If you do prefer to stick with cannons, which I also don't like due to recoil, I would consider something like chain-shot that could also be used to do more penetration based damage rather than bludgeoning. [Answer] First and foremost you need to think about the size of your gasbag relative to the size of your vessels. With a large enough gasbag, split into as many small gas cells as possible, an airship could be peppered by long-range cannon fire all day without significant damage. This would force conflicts to take place at shorter range. In order to make your airships light enough to be realistic, you'll need to drop the thick oaken construction present on historical fighting ships and replace it with much more lightweight materials. Your ships simply can't afford much in terms of armour, so more focus will be put on smaller weaponry like deck guns, 18lb cannon, and maybe swivel guns. None of the huge 32lb cannon from the Men O' War! With all this in mind, you can certainly do damage with smaller cannon. Accurate shots at the supporting masts and rigging will be more damaging to your enemy than hitting their gasbag, possibly forcing their retreat if they think the whole thing is at risk of tearing off! Swivel guns and carronades can be devastating against an enemy crew, and I would expect gatling guns to have a similar effect (though these would be much more accurate than a carronade loaded with grapeshot). In terms of balance, the gondola of the airship where the cannons are mounted would be suspended below the gasbag and would certainly swing with a broadside, so it might become better practice to fire off the cannon one at a time. It should certainly be possible though. Tactics will be vital during an engagement. The ship with the wind gauge historically had an advantage (that is, the ship with the wind on their side could dictate the terms of a battle), but with airships altitude will be much more important. Get above your opponent and you can drop grenades, cannonballs, flaming torches or tree trunks on them, and with their own gasbag in the way they'll be unable to do much in retaliation. Rockets are a particularly good choice in this scenario as they don't require a big, heavy tube of metal (a cannon) to be fired - just a tripod. With the addition of fins they can be reasonably accurate, and inflict terrible explosive damage on your foes. I don't know if gliders will be particularly feasible, bearing in mind that for them to be at all useful you'd have to launch them from a high altitude above your enemy - from where you'd already have the advantage. The gliders would get a single pass on your enemy before being too low to be effective, and then they'd need to be picked up again - possibly from enemy territory, or the middle of the ocean. The manpower (and weight) would be put to better use on more guns. [Answer] All the other options pointed out nicely why and where the limitations of cannons are. Too much weight, too little impact on the gas balloon. I would like to point out a big advantage of the small calibre guns like gatling guns, though: The airship has a huge baloon, but a relatively small passenger compartement below. It can't be armored, since weight is obviously a problem, so it is most probably made from wood. Shooting that with a small-calibre gun is going to send wooden debris and splinters flying everywhere through the passenger area, and crew and sensitive material will be "damaged". And if you lack the crew to maneuver your airship... right. So i do see a lot of potential and good use for small-calibre "automatic" firearms. I do also see something else that might be interesting: fire. Fire of any kind must be the bane of airships. Yes, i know, helium fillings will not make these airships [go Hindenburgh](https://upload.wikimedia.org/wikipedia/commons/1/1c/Hindenburg_disaster.jpg) on the first hit. But it might still burn the hull down, releasing all the precious helium into the sky. And if the crew compartement is on fire - how on earth are they going to extinguish it, having no water? I might imaging they try to use helium to do it, but that helium will be missing later for other maneuvers. So what about flame throwers, incendiary ammunition and .. mortars? Installing one or two mortars on an airship might be possible. You need an [incendiary payload](https://en.wikipedia.org/wiki/Napalm) on your mortar bombs. Time the explosions just right, and you set a huge part of the enemy airship aflame. That is by the way what i would suggest for rockets, too. [Answer] The statements about blimps staying in the air after being riddled with bullets reminded me of one episode of the TV show mythbusters. There they found out that caltrops took very long to deflate a car tire. That made them test caltrops made from hollow tubes and the result was an instantly flat tire because the air rushed out of the tube sticking in the tire instead of slowly leaking out of the tear. So perhaps ballistae shooting hollow spears designed to stick in might do a better work? Sure, airships have a rigid skeleton and through that less pressure in the envelope but it might be a way to speed the downing. Especially if you manage to some in low and some high, that could create an air flow forcing helium out on top which is replaced by ambient air. [Answer] Talking solely about weapons, weight is a really big issue when it comes to airships, due to their mode of lift. Another thing that others here pointed out that puncturing a gasbag would be rather effective, if you have multiple gas bags it'll be much harder to puncture enough for the loss of lifting gas to be of enough for its crew to surrender(its more common to force someone to surrender rather than killing then by blowing then up). So, now that the needs have been laid out, lets design. I'm thinking a pod mounted swivel ballista would be rather good as a primary weapon. It's rather lightweight(compared to something like the smoothbore cannon use on many earlier sailships) and has a good damage output,espicially if you can slap some pyrotechnics on that. Size/appearance wise, it could be comparable to a really big crossbow mounted on a swivelpod, just imagine that in your head. Seems rather good, in my opinion plus they have a much larger field of rie compared to a normal canon, considering its turret like design and placement. Now, we have one weapon, but just cuz I thought of it, lets make another. Rockets. As many others have shown here, rockets would definitely be a viable weapon, but its got a few downsides. For one, they are slow. Against even an Airship as a moving target, its got a short range it can hit, especially compared to something like the ballista above. And also, they are very unsafe. I mean, its like literally putting a bomb or fire on your ship, ready to explode and burn at the slightest touch. Not very good, especially since you will most likely be using hydrogen as a lifting gas. But I think they still have a role, just as torpedoes were still use alongside the main cannons of many ww2 era warships. Plus, aimed down it could attack ground targets, assuming you aren't already shot out of the sky by whatever counts as small arms fire in this era. [Answer] If you want to bring down a helium airship, your best bet is going to be a large explosive charge (or charges) detonated inside the gas envelope. That should both cause overpressure-based rupturing of the envelope and force helium out, replacing it with combustion gases (which will be much denser than the helium, at least after they cool). Incendiaries are also well worth considering - it's likely that the Hindenburg's fire was mostly the skin of the airship, and not the hydrogen inside. How you create a delayed charge with 1850's tech is another matter; but it's not impossible as shrapnel shells existed in those days. Given the thin skin of the airships, the complex nature of the munitions and the need to lift the weapons using an airship (giving significant weight restrictions) relatively low-velocity weapons would be the way forward - think howitzer (or even rocket, if they can get the accuracy up to an acceptable level) rather than cannon. If you want to attack surface targets, then bombs would be the way forward. Ground-based air defence would still need cannon, in order to achieve sufficient altitude. [Answer] barbed chain shot and spider shot would be fairly effective against airships, tearing large holes is what you want. with 1850's tech there will be a lot of wood and rubber coated fabric in your airship so incendiary devices, like fire rockets and light weight carcass shot should also be common. if they do have cannons they should be bronze, they are lighter and on an airship weight is everything, even then they might have one or two at most. ground defenses however where weight is not an issue would love to use cannon vs airships. As someone mentioned weaponry is less of a problem then how to make your airships move. ]
[Question] [ In the scenario proposed in [this question](https://worldbuilding.stackexchange.com/questions/34475/what-would-north-america-look-like-if-the-states-werent-united), the Thirteen Colonies choose not to unite. Sure they work together, but not as a United Nation, as a coalition of Independent Nation States; all working together, but all technically independent of each other. As much fun as [this scenario](https://worldbuilding.stackexchange.com/questions/34475/what-would-north-america-look-like-if-the-states-werent-united/34542#34542) is, I cannot think of a realistic reason for it to occur. Why would the Thirteen Colonies choose to be allied, individual nation states instead of being one united country? [Answer] They might chose to remain apart because the colonies did not really have that much in common in the first place. While all the colonists spoke English, and the vast majority of the residents at that point (~1790) were of English or Scottish origin, the economies of the states were dependent on different things. ## Characteristics of the Colonies New England's colonies were based on fishing, whaling, shipbuilding, and shipping. They were heavily involved with the non-English colonies in the Carribean, as shippers of food to the plantations there and processors of molasses (into rum). There were basically no slaves in New England (less than 4,000, about 3/4 of them in Connecticut). The population of New England in 1790 was just over 1 million. The middle colonies (NY, NJ, PA, DE, and MD) were sources of the food that the New Englanders traded, and also furs. Furs were the primary product of the interior United States and they flowed through Pennsylvania to Philadelphia, or down the Hudson to New York. There were some slaves in the Middle States; about 150,000, 2/3 of them in Maryland. Maryland is often considered a slave state, but it is the only 'traditional' slave state whose slave population dropped after 1790. Whereas the number of slaves in the US tripled between 1790 and 1860, it dropped by 10% in Maryland as the state shifted away from the plantation economy and Baltimore came to more closely resemble Philadelphia as a manufacturing and shipping hub. The free population of the middle states was 1.2 million. The South sold cotton, tobacco, and indigo. Since the south's trade was more lucrative and population of free whites was MUCH smaller, the south had no incentive to start manufacturing, whereas Philadelphia, New York, and Boston had manufacturing economies as advanced as anywhere outside England, even as early as 1800. Slaves were of course plentiful in the south, making up close to half the population. The free population of the south was about 900,000. ## Economic Considerations Economy pulled the country in different directions. The South would have wanted to maintain ties with England, since that was the richest country in the world and the primary customer for southern cotton and also indigo. New England, on the other hand was basically in competition with the British shipping and shipbuilding industries. The New England colonies would have been geopolitically advantaged by an alliance with the Spanish colonies in the new world, a huge market for New England manufactures and shipping. At this time, Spain had little manufacturing and a small merchant navy. The middle colonies would have been been somewhere in the middle (lol?) not being especially advantaged or disadvantaged by association with England. As the only net food producers of the New World, they would benefit most from the growth of other colonial empires that they could feed (perishable food being difficult to ship across the Atlantic). Economic difference caused a potential for separation between the states. The impetus for separation could be one of the below: ## The Elephant in the Room This was of course slavery, the issue which came the closest to actually splitting the nation. In addition to the actual civil war, there were tensions around the 3/5 Clause of the Constitution, the Missouri Compromise, the Nullification Crisis, the aftermath of the Mexican-American war, etc. Had the issue gone to war during, say, the Missouri Compromise of 1820, its entirely possible, the New England, Middle, and Southern sections of the country would have gone their own way. This is especially true since the New Englanders voted differently from the rest of the nation in the 1820s. New England provided 31 of 34 dissenting electoral votes against James Madison in 1816, and the only dissenting vote in 1820. NE voted 51 of 51 for John Quincy Adams while the rest of country voted 30 of 210 for him in 1824. In 1828, NE went 50/51 for JQA, and the rest of the country 33 of 210. ## Ratification The other event that could have split the nation was ratification of the Constitution. It was a heroic effort on the part of many of the founding fathers to convince state legislatures to ratify. As it was, two of the original 13 states (North Carolina, and Rhode Island) had not even ratified the Constitution by the time George Washington too his initial oath of office. Many of the largest states,had close votes: 187-168 in MA, 89-79 in VA, 30-27 in NY. Rhode Island rejected the constitution in a referendum, and North Carolina's legislature voted once against ratifying before coming around later. Incidentally, that means that neither state nor NY voted in the first presidential election. Imagine if you weren't allowed to vote and then Hillary or Trump (pick who you hate more) became president! In any case, if ratification was a close call in many places, and could have failed. In that case, it is not at all clear what would have happened, but three regional nations, or 13 individual nations are both possibilities. [Answer] Simple answer is that the Articles of Confederation were a pretty big failure which could have lead to the "US" to devolved into 13 sovereign states, rather than what did happen (the writing of the Constitution and strengthening federal power), however when British forces attack in 1812 they would need to "unite" as an alliance to ward of the UK which is another point of a possible Federalization, but it is more likely to establish a long term International alliance between the 13 states rather than a federated government due to the states would have stabilized by this point and there would be much greater push back against a stronger union since they'd have already seen it fail once. This also would be on the tail end of the French Revolution. Many of the founders of the US likely would have seen that and a good number of them would have to question how lucky they were that the results were as they were and wouldn't want to risk pushing more political reform that could end worse. This obviously changes history a bit like, no war with Canada and the Civil War never happens, but alliances would change and the North would block the South from searching for slaves in its territory at some point, especially with the South growing military power... Slavery would still be abolished by the early 1900s and racial tensions wouldn't be as high... Also Southern cities might be more powerful than they are today. The Louisiana Purchase wouldn't happen, which might have causes another state to form there and possibly war with the 13 states. The US wouldn't have been able to back the Allies side in WWI or WWII which might have lead to a German and Japanese victory... California, Texas, Hawaii would all likely be their own countries, bigger, with other smaller countries around them probably. Alaska might have been bought by Canada. Also the moon landing would likely not have happened and I think the Space age would have been pushed back a few decades. Same with all our current technology without the US pushing for and having the resources to do these things. Also you have a lot of oppressed people throughout Europe that would likely overthrow Germany eventually and China would never stop trying to rebel against Japan so that area would likely be a chaotic area similar to Africa. Without all the superpower rising up and all the war in other countries far away the nations that are the US and Canada currently would likely be still the most peaceful area on Earth, but tensions would rise and there'd be minor skirmishes, but ultimately there'd be no reason to unite so under anything other than maybe a looser confederation than the Articles of Confederation did, more in line with a UN or Nato. [Answer] Look up real history: The United States in 1776 was indeed a federation of independant states (“state” is like kingdom but not specific to monarchy; different from the meaning assumed today as a synonym for provence). The [Constitution](https://en.m.wikipedia.org/wiki/United_States_Constitution) created a central government, 11 years later! The Wikipedia page gives a good overview. Look at what happened: they planned a meeting for the stated purpose of ammending the Articles, but took matters in their own hands and wrote an entirely new government, and then had to convince everyone to switch to it! Why were they driven to that? Maybe they weren’t so driven in the alternate history, and a few significant ammendments would be sufficient to address the problems, or the same problems were not even present due to diplomacy and events prior to getting to that point. Maybe the founders had ideas but couldn’t agree on a federal government so didn’t persue it but revised the Articles instead as they were supposed to. Maybe one particular person was present and made them do the job they were meant to do and not waste time on a more ambitious project; work on that after we ship our deliverables, as a good manager will do; but that ended up working well enough and a whole new government did not gain traction. Maybe Jefferson had died early, or wasn’t present for some other reason. So it’s the fact that we did create a Federal Union that is extrodinary and if anything had gone differently it would not have happened that way. Now even with a full Republic having feneral authority, states rights were a big deal and it wasn’t until WWⅡ that the US became such a strong single federal entity. It could have gone differently with events weakening the central-ness, even without changing the fact of the Union. Again, look at the intracacies of history to get a much more varied story than you might know or suppose today. [Answer] More of a comment than an answer, but as many of the posters upthread noted, The initial "Articles of Confederation" were based on the premise that each colony was a sovereign State, and the correct terminology for the nation prior to the Civil War was "These United States". The American Creed also outlines this historical basis: > > I believe in the United States of America as a government of the people, by the people, for the people; whose just powers are derived from the consent of the governed, a democracy in a republic, a sovereign Nation of many sovereign States; a perfect union, one and inseparable; established upon those principles of freedom, equality, justice, and humanity for which American patriots sacrificed their lives and fortunes. > > > I therefore believe it is my duty to my country to love it, to support its Constitution, to obey its laws, to respect its flag, and to defend it against all enemies. > > > And historically, some of these early States really did take the idea of Sovereignty to the limit; the "Whiskey Rebellion" of 1791 was a direct challenge to the idea of "These United States" being a unitary nation, and the events leading up to the American Civil War were based on the principle of "States Rights" and how much authority the central government in Washington had over the States. Slavery was the proximate cause, since it was also an emotionally charged and easily understandable issue, but the idea that Washington could restrict the spread of slavery to the new territories was the trigger for many of the Confederate states, since they could collectively see the end of their power and influence as they became outnumbered in the expanding Union. The CSA is probably a good forecast of how a disunited States under the Articles of Confederation would have evolved. Even under the existential threat of military conquest, the various States that made up the CSA never operated in a unified manner. One could suggest that the squabbling States of the original Articles of Confederation would have been unable to drive out Spain or France from North America, and the British would have been able to create a sort of counter nation on the West Coast, retaining the Oregon Territories and joining them to British Columbia, and expanding north to Russian Alaska and south the Spanish California. France still retained notional rights to the Louisiana Territories, and the interior may well have been left to the plains Indians. [Answer] Durakken suggests that the Articles of Confederation basically failed (which it did). kingledion suggests that differences in manufacturing base and preferred trading partners and attitudes on slavery and loyalty would have kept the colonies apart. Those are both great ideas. Perhaps another option would be if England did not force the colonies to unite in the first place. The Seven Years War (or more to the point: the "French and Indian War") began when England decided to stop French expansion in the inland areas. Ben Franklin had the bright idea that maybe the colonies should create a unified governance for defense of the 13 colonies, thus proposing his Albany Plan and calling for the Albany Congress of 1754 (twenty years before the first Continental Congress). Maybe, just possibly, if England had decided to wage a Continental war (in Europe) and focus its strong navy and commit troops to attacking France directly (along with its ally Fredrick the Great of Prussia), the New World could have been spared as a theater of the War. England, knowing that France did not have a navy strong enough to transport troops and supplies to win in America, might have decided that America was theirs for good and that England should therefor focus military action directly against France. This would mean the Colonies would have less to fear, and they might not have felt the need to unite in defense. Also, maybe England would instead decide to wage economic war against France, and to treat the Colonists a lot better then they actually did. England regarded its colonies as golden gooses that you just squeeze the crap out of. Thus, you get bumbling moves like the Stamp Tax. What if, instead, England had decided that the better way to extract wealth was to invest in growth and productivity, rewarding entrepreneurship and fostering strong market development. As kingledion points out, each colony had different things to offer, and under an English crown, these differences would be skillfully exploited for the good of the Crown, but also for the good of each colony individually. If each colony is relatively happy with its relationship to England, then there's nothing to rebel against. Call off the tea party. ]
[Question] [ Let's say history went on as it would have with one major exception - a virus/series of viruses decimated the European/Asian populations repeatedly to such a degree that they simply could not advance as a society technologically. Now, the Americas are untouced by this, whether it be by immunity or by simple lack of exposure and have progressed to modern tech levels. Is it possible to reasonably predict how long it would have taken them, from say, 1300, to do this? I like to think the Inca were on bar with early Greece technologically speaking if it helps, though I may be wrong. Answers should take any natural effects into account (e.g. climate, weather, availability of game. [Answer] I would say, likely never, barring outside influence. Even when you look at Europe, it was a near run thing, more a matter of luck at times than anything, and Europe had lots of advantages. In Guns, Germs and Steel, Jarred Diamond argue that the Americas would always be slow to develop but the primary orientation of the continents were North-South instead East-West as in Eurasian (Africa has the same problem.) This causes trouble because biomes are largely defined by latitude, which defines their temperature. Closer to the equator, hotter, closer to polls colder. That means that as you move East-West, the temperatures stay more constant than they do moving North-South. Plants and animals can migrate or be traded East-West but far less easily North-South. Traveling East-West, you just need one suit of clothes. Traveling North-South you need several, one for each clime you will cross. In civilization and technology building, the key factors are population size and trade. Populations tend to stick to biomes and grow East-West so if you have a primary North-South geography, you see a lot of smaller chopped up cultures and civilizations that are relatively isolated. Population is necessary just for the surplus material a large number of people can produce and just for all the brain power it provides. Large population can also more easily back up information and survive cataclysms. Trade is necessary to increasing technology because no place on earth has enough resources in a radius of 100-200 miles to support a Renaissance technology level. Also, trade is necessary to prevent civilization from collapsing from famines. If your primary travel corridors run North-South, population gets chopped up into small cells, the spread of useful plants and animals is very slow and general travel and commerce, much more difficult. The other problem with Americas is that they do not have native animals that can be domesticated, especially beast of burden. Diamond spent a lot of time pointing out that of the millions of mammal species only about a dozen have been domesticated. Domestication requires certain behavioral traits that not all animals possess. Attempts to domesticate Zebras for example, have been attempted by Islamic and then later Europeans (Zebras are immune to the tsetse that wipes out horses in Africa) but the animals are just too belligerent and easily startled. In the Americas, the only animal that could even be considered for a beast of burden would be the buffalo, and even after a couple of centuries of people trying to raise them, they are still not domesticated just in terms of keeping them for meat and skins. Trying to yoke one is out of the question. I think that culture in the Americas would cause a serious block. I would argue that the means of organization are a type of technology themselves, one that allowed them to accomplish more than any other cultures ever did with the same available resources. But they also created a serious early adopter trap that would have prevented further development. The conditions that lead to the flourishing of technology, art and science are not natural and not stable. The progress of humanity is a story of this or that small polity suddenly and usually by chance, being forced to adopt a more egalitarian and merit driven society. Then they have a run of 200 years or so, and then fall back into a static, hierarchal, parton-client system where birth and political connections mean far more than merit and class mobility freezes. Then the locus of advancement jumps somewhere else. Human progress is more about following a golden thread from small pocket to small pocket all over the world for centuries. Key to such development is escaping centralized authority and control with a subsequent increase in individual freedom and merit reward. Empires strangle off development fantastically. You can see this in the fall of the Islamic world after the Ottoman Empire absorbed most of it. A dynamic civilization slid into stagnation because Empires seek stability more than anything else and progress does not bring stability. But the cultures of the Americas could not easily dispense with centralized authority. With only stone and wood tools to work with the high civilizations of the First Americas-peoples relied on an incredible level of social and task organization ito marshal vast amounts of skilled human labor to overcome their lack of metal tools and draft animals. They shaped stone by pounding it, not chiseling. They moved stone by huge teams of men, not by yoking oxen and so one. While powerful, reliance on organization made the societies fragile. In Meso-America, almost any kind of social disruption caused city states to collapse economically and for their people to abandon the city, sometimes for decades or centuries. The kind of wrenching social change in Europe that drove the the Renaissance would have simply destroyed the civilizations of Americans. So, I think the answer would be "never" but if they did, it would take thousands of years. [Answer] This is a toughie. # Limitations Transportation. Transport in the Americas was over land, whereas in Europe, sea-transport was available. Imagine a hand splayed-out as if it were Europe, where you could go in-and-out with ships much faster than over mountains, forests and deserts. Land transport did not excel past sea until the railroad. Your early Roman empire adapted quickly to the sea for expansion, whereby your fictional American empire might not have interest in overseas travel. Horses were not available, either. For your story, you may want to develop a way to travel overland very quickly, or provide an impetus for your sea-faring experts to go along the coasts by sea instead of walking along the land. Diversity and Population. The benefit that Eurasia and north Africa had was connections with different cultures and a great diversity of skillsets in the by the time the 1300s arrived. Further, there was a much larger population. The population in Europe was [more than 17 million](https://en.wikipedia.org/wiki/World_population#Antiquity_and_Middle_Ages) in your time-frame, versus 2 million++ in the Americas. Either give your 'Americans' a strong, and healthy, growth or an innovative spirit to compete and diversify. You have the geography, but not the demographics. One suggestion is to start having the character areas rapidly develop in diverse, independent, but cooperative ways. ## Benefits Geography. The Americas have pretty much almost every biome that Euro-Africa-Asia have in different doses. In order to get the same fauna, you can either adapt the existing ones (maybe they domesticate buffalo?\), or maybe they brought more animals with them previously in your alternate-reality. Therefore, your flora and fauna could be equally beneficial. Solution from 1300AD?* Highly, highly, highly speculative and optimistic: Generation A - more interest in agriculture for distilling and saving food. Generation B - developed interest in trade and communication. Generation C - specialization of jobs. Generation D - science & astronomy, mathematics, materials-science, engineering, and governance. Generation E - evolution of a more mature and elaborate class system (I'm not saying this is a good thing), and you've got your renaissance. Your question is difficult and very open, but I took a stab at it. More importantly, \- I laughed out loud at the buffalo-riders. [Answer] Wow, I don't know how one could possibly say. Maybe forever. Why were they so far behind Europeans when the Europeans arrived? Their technology appears to have completely stagnated. When Europeans reached the interior of Africa, the people there were still living pretty much as they had for thousands of years. It's not like they were a few years behind Europe and catching up. They'd gone nowhere for a long time. If Europeans had never arrived, would the Aztecs and Incas have started moving forward at some point? Maybe. Maybe not. What causes some cultures to have technological progress and others not? Historians debate that endlessly. Reasons suggested include various aspects of the culture, environment, religion, genetics, etc etc. [Answer] What would it take? A lot, and then some. But good news: it is certainly possible! The Inca, Maya, Aztec, and various tribes of north america had all various technologies that were advanced and if used in unison complementary. So I will make a list of things that in my opinion have to happen for it to be possible: 1. The Mayan empire must survive until the Aztec empire and not be obliterated by it. Both should live beside each other like France and Britain did as a comparison. 2. One of those civilizations has to discover bronze. 3. They all become seafaring (most of them already are but not advanced enough to go very far) 4. All of them expand a lot, in the case of the Aztecs they expand north and Mayans south. 5. They end up encountering each other and sharing technology, the population grows a lot, and exchange happens between them (also war). 6. The component technologies allow them to achieve some parity with the europeans. Admittedly they will lag behind in some areas, but will be forward in some other areas namely astronomy, engineering and maybe* mathematics. 7. This is optional, the Vikings settled north america and exchanged tech with the natives and maybe even the aztecs! This will give a considerable boost to the theory and greatly reduce the time required. I estimate that this would take at least 700-1500 years more or less. Based on the fact that the Incan empire took 100 years to be founded. And being optimistic about the discovery of bronze. It is worth remembering that the Incas, Aztecs and Maya already had metallurgy so this may be an argument for their so called early development of bronze compared to the greeks for example. [Answer] I suspect there would need to be some kind of society level shake up somewhere to get things moving more than anything. I know a lot of real scientific research in medieval Europe was done in monasteries, and that's because monks had time, money and a desire to understand Gods creation. Monasteries also tended to be near water, which acted as highways of resources and ideas. I would be included to go with some kind of stable empire who's ruler decided setting up monastery like places were a good idea from a piety point of view. You've got a bit wiggle room for the time scale I think, culture is far more important. I would also avoid nomadic and small tribes as sources anyway, you need the surplus resources of a nation/ empire of some kind to allow a caste of thinkers and tinkers to develop. [Answer] Every culture uses technology to serve its own purposes. The Incas valued rope for bridge building because it was durable and flexible. The French valued stone for bridge building because it was exactly the opposite: solid and reliable in keeping its shape. That's just one example but it points to a greater trend. You can't really easily compare levels of technology between such tremendously different and diverse societies as those of Europe and North America and South America. They have such different goals and available materials that technology won't advance in a linear and constant way in both regions. This scenario is cool not because of what Will be (the Indians achieving some arbitrary level of technology), but because of what could be (the Indians doing their own thing and advancing for a couple centuries more without going extinct from smallpox). Native Americans would find some pretty novel solutions to the same problems the Europeans solved and they would do it at their own pace like everybody else. I hope that didn't sound preachy or anything. :) ]
[Question] [ What other hypothetical alloys could be used for ancient/medieval era weapons/armor? * Don't use made-up elements (or alloys, if possible) * Assume metallurgical technology up to the medieval age (in any of Earth's societies, such as Europe, China, Japan etc.) * Assume normally rare elements to us could be in abundance (perhaps those from meteorites or other similar objects) * Consider various types of strain, density and various types of stress to determine good candidates EDIT I've changed the question to put more emphasis on the alternative alloys part rather than the rare elements part. Is it really the case that given different circumstances, the same weapon alloys would be made? For example: steel and bronze. [Answer] Ultimate tensile strength Let's start by making the usefulness of an alloy measurable. I'll use the unit [MPa](https://en.wikipedia.org/wiki/Ultimate_tensile_strength) as a proxy for of puncture strength. For the sake of comparison, here are some values: * human skin: 20 * aluminium: 45 * gold: 100 * copper: 210 * iron: 350 * brass: 550 Judging by this table brass appears to be the best choice for armor and indeed it is. At least as long as you don't want to move so much. Brass has a higher density than iron (8.7 to 7.8). Also you need to keep in mind that brass is more expensive than iron. Precipitation hardening Now, in order to get some decent alloys your civilization needs to know the art of [precipitation hardening](https://en.wikipedia.org/wiki/Precipitation_hardening) which ain't that hard if you use materials which have a low melting point like aluminium. Magnesium Alloy If your civilization discovers magnesium (high probability as it is earths fourth most abundant resource) you have another high potential component for creating strong alloys. If you'd put aluminium and magnesium together you can create a very strong alloy with a MPa of 450 ([Aluminum alloys](https://en.wikipedia.org/wiki/Aluminium_alloy)) and very low density, making it lightweight armor more powerful then iron. Using a lightweight material like this would allow you to construct plate-armors in which you could move around more freely or a chainmail nearly as light as a leather armor but much more pierce resistant. Using it as a weapon on the other hand has the weight disadvantage as you need some weight to cut through armor or break some bones. You should therefore not use it for a non-cutting weapon. There are much more aluminium - alloys and magnesium alloys. Take a look yourself, but most of these alloys demand a higher level of technology. Take a look at the aluminium-zinc alloy with an MPa of 700 for example. Cermaic Armour Plates You could use ceramic plates in vests to get a high penetration-protective armor. Ceramic is used in a lot of modern composite armors and bullet proof vests. Ceramic armor is however a one-use armor as the ceramic tends to shatter after receiving a blow or two. As ceramic is much lighter than steel or iron, ceramic vest seems to be useful to skirmishers - fast attack, fast withdraw, minimal casualties. Silk Armour This sounds ridiculous at first, but the Mongol horde used silk armors which were much more penetration-protective than European plate armor. Above the thick silk armour they've worn a scale armour to protect them from cutting damage. The silk armour was super effective as it was very light an hardly penetratable by spears and arrows alike. Silkworm silk has a density of about 1.3 and an MPa rating of 500. It's obviously not suitable as a weapon. [Answer] The development of bronze (and it was the king of metal weapons and armor for about 5 millennia) is due to a number of factors. First, it is (obviously) derived from copper. And copper has a number of peculiar advantages. First, copper ore deposits are often associated with small amounts of native copper. Copper has two relevant virtues: it has a low melting point and it can be work-hardened. So those lumps of native copper can be made into weapons that are superior to bone and stone without an enormous tech base. And the copper ores found nearby can be purified by just heating (rather than requiring a non-obvious flux), so the same techniques used to work native copper might lead to the discovery of smelting without too much effort. Once the general idea is discovered, it's not unreasonable to hope that some metal worker of an experimental frame of mind will take the idea further. It didn't take much to notice that adding other metals produced a metal which was much easier to cast, and was stronger and harder than pure copper. (ETA - Although those additional metals were added as other ores or minerals, rather than as finished ingots.) The first bronzes were arsenic bronzes, but at some point it was noted that tin gave superior results. This was not immediately useful, as arsenic was often associated with the ore complexes that produced copper, but by Roman times the exploitation and trade of British tin mines was well-established. Alloying copper and zinc produces brass, which is actually harder than bronze, but the major zinc deposits are in North America, Australia, and Iran. The first two don't count, but it's not clear why no trade was established to provide Iranian zinc to replace British tin. There are several other possible bronze alloys, especially aluminum and silicon. Both of these require much higher temperatures than tin. So, for development of copper alloys, arsenic bronze, tin bronze and brass are about the only contenders, and it's just not clear that there's much to choose between them as far as weapons and armor go. Are there any alternatives? Looking at what produces native metals (to get the development process going), not much. Gold and silver (while tempting from an aesthetic point of view) can be melted at low temperature, but they just don't produce materials that are either strong or hard. Some of the platinum group metals (like platinum, for instance) can produce a fairly hard metal, but they all have high melting points. Other metals which have reasonable melting points tend to be soft, and the harder metals tend to have a high melting point. Before the development of coke, even iron was very difficult to melt, and was usually produced as blooms which were purified by working (hence "wrought" iron). Plus, of course, many are difficult to produce as they oxidize rapidly at high temperature. So, all things considered, the only semi-major change I can suggest is the replacement of bronze with brass, and that means your fictional society hasn't made it into the Iron Age. [Answer] I'll add on answer despite one being already chosen since I want to add some things that I did not notice being mentioned and it doesn't make sense adding a "list of stuff nobody mentioned that I could see" as a comment to either a random answer or the question. Copper alloys Already mentioned by others, but I noticed nobody mentioned why people transferred to using iron as soon as they had the technology. Simply put copper alloys are too ductile. If used as weapon they have a tendency to deform, bend, and lose any sharpness the brownsmith tried to give them. This makes them pretty much useless for any weapon with a point or edge. And weapons with a length of metal such as swords and some polearms would have issues with bending. On a positive note they are hard to break, which is why they were used for cannons and cartridges. Similarly they would probably (if cheaper due to the metals being more common) see use in armor. Bronze and brass actually were used in armor despite iron being available, if it was affordable. Meteoric iron First thing that occurred to me with some metals being more common than on Earth for some reason. If the area of your civilization was hit by a rain of iron-nickel meteorites, meteoric iron could be common enough to cause a fundamental change in metallurgy. Why does it matter what kind of iron you use? Because meteoric iron is actually a nickel-iron alloy. It is found as pure alloy, no refining is needed. The nickel content also gives it much better corrosion resistance. Most alloys are also easier to work than iron, I think. As a bonus it can have an exotic crystalline structure that looks pretty, might be magnetic (aka "magic") and can legitimately be said to be a gift from heavens. A side-effect is that such abundance would probably be localized, so a specific area would probably have big edge on availability. Also note that nickel is not that rare, so iron-nickel or cupronickel alloys might be possible solutions also. I doubt anyone would invent that without having metallurgy good enough for steel though. There is also similar "telluric iron", if you dislike gifts from heavens. Wood Bamboo for example can be hardened to make decent knives and good spears. While metals are usually better you can actually make weapons and armor from wood. And the superiority of metals is only an issue if your opponent actually has metal equipment. For building a setting it isn't that big a deal. As long as you remember the limitations that not having iron tools would cause for agriculture, masonry, carpentry, and the many other things that were transformed by access to cheap metal that keeps an edge. Glass You can in theory make weapons and armor from glass. It just doesn't make any sense if you have access to metals. The big issue is the brittleness. Glass has tendency to shatter on hard impact. This is not a good feature for a weapon or armor. The simplest solution should be to laminate it with a material that prevents the cracks from spreading. Brass, bronze, copper, silver, gold, or their alloys should all work if the the layers are thin enough. Note that you do not need lots of the metal. Also note that actually manufacturing such a blade would almost certainly be a major pain. It really does not make any sense if you can use bulk metal instead. Although a glass-gold laminate sword would be pretty cool... And would have the corrosion resistance to be a "sacred relic" for a very long time. Probably could outlast the species that created it. In a fantasy story a sword that was created at the dawn of time and has been sacred to multiple dominant species as they rise, flourish, and finally go extinct might be nice story item. You'd probably want to make only the edge of the laminate and the rest of the weapon from wood in construction similar to what the Aztecs used with obsidian. Although the laminate would be more durable, so you could use a single blade instead of multiple microblades. It never makes sense to make glass armor pre-modern since you can use wood, horn, hardened leather and cloth armor instead. The composite structure needed is just too complex without modern technology. Stone You can make weapons and armor from stone as there is really a wide variety of stone. Invariably they lose to metal in the ease of working them into durable forms. But if metal was unknown or unavailable and suitable stone was common it might happen. Or perhaps only swords made from jade can cut the demons and jade armor protect from their corruption... Still stone can be used in combination with other materials to make effective weapons and armor. Essentially the other material supplies forms and resilience while small stones attached or embedded supply the hardness. Concrete is actually such a composite with different goals. Such weapons and armor are practical but require lots of work and maintenance. As I mentioned before the Aztecs had a "sword" with small obsidian blades forming a cutting edge. It was fairly effective until it hit metal armor... Summary Of the above the meteoric iron is probably a usable answer. Bronze alloys, wood, and stone fall into the category of "good to know and might be of marginal use sometime". Like I said, this is kind of an extended comment that does not fit as a comment. The glass section is just a curiosity. It is probably too complex to be invented by a civilization that actually needs it. But if you want something really weird that comes from the distant past or a really exotic race... [Answer] A trio of things for a dangerous combination would be Brass, Bamboo, and Laquer. Add Resin to the mix, and you have a powerful set of tools for laminate armory and weapons. Event early iron would have trouble competing against this combo as the flexible bamboo would help the brass keep it's shape, thou not the edge. Hardened Resin and Laquer could be honed to a sharpness close to glass. Reinforce the back edge or center with bamboo, coat the edge in Laquer , and hone to sharpness. (Would provide links, but working from phone. Laquer was used in Ancient China both as a clear seal, and tinted. It was derived from some kind of sap. Resin was another sap based material that the Viking and Celtic cultures used for sealing boat and ship hulls.) [Answer] Comments here have mentioned [Nickel](https://en.wikipedia.org/wiki/Nickel), but another excellent candidate would be [Manganese](https://en.wikipedia.org/wiki/Manganese). Manganese is added in small amounts to many steels, but if you make it from 12%-15% of your mix, you end up with [Manganese Steel](https://www.sciencedirect.com/topics/materials-science/manganese-steel), also known as [Hadfield Steel](https://en.wikipedia.org/wiki/Mangalloy). Manganese, and to an extent Nickel as well, can allow steel to remain in its Austenite phase at room temperature. [Austenite](https://en.wikipedia.org/wiki/Austenite) steel is fundamentally different from the steel you're likely used to. One weird quirk is that it's not even magnetic. Normal carbon steel only turns to Austenite at over 727C. It is significantly softer than ordinary steel, but also significantly tougher as a result. For an added bonus, Mangalloy steels are incredibly work-hardenable! This means the more you hit them with say, a hammer, the harder the surface gets! This allows for armor that has a hard surface layer, with a tougher under-layer. Hadfield steel was the first steel discovered that behaved fundamentally differently from carbon steels. Before it, one had to choose between hard but brittle high-carbon steel, or soft but tough low-carbon steel. While there may be better elements to add to your steel armor than Nickel or Manganese, for instance [Molybdenum](https://en.wikipedia.org/wiki/Molybdenum), both Nickel and Manganese can be extracted from their ores by smelting in a manner similar to Iron. The elements are even often found nearby! [If you still have trouble finding a good vein, balls of the stuff just grow on the ocean floor.](https://en.wikipedia.org/wiki/Manganese_nodule) (Hope you know a mermaid!) Of course, knowing little about Manganese your Medieval people would not know about its properties, even if the technology needed to produce it is simple enough. [Answer] Metal is meh. Least as far as armour goes. Composites are probably far more useful, and yes, you could make decent composites with horse glue and cloth. There's a few possibilities for useful, exotic materials that would have been available to medieval folk, either in conjunction with or instead of regular materials. Layered fabrics with glue in between would likely have been useful against stabbing and slashing weapons. While the variant that came to mind was the [Greek linothorax](https://en.wikipedia.org/wiki/Linothorax). However while the Greeks used linen, silk might be a useful fabric here - done [correctly it's bulletproof](http://www.theguardian.com/artanddesign/2014/jul/29/bulletproof-silk-vest-prevent-first-world-war-royal-armouries) and the Mongols used it as part of their armour. I'd suspect rather than a single material, a mix of materials and layered armour, would work well. If we wanted to go a little nuts, maybe domesticated spiders for super strong silk. As for weapons, once again, there's interesting options that are not metal. Obsidian made good sharp blades, and I suspect that whole glassworking wasn't quite to modern standards, even crappyish glass could be sharpened into something stabby or slashy, maybe used like the a [Macuahuitl](https://en.wikipedia.org/wiki/Macuahuitl) or [Tepoztopilli](https://en.wikipedia.org/wiki/Tepoztopilli) [Answer] Something that I don't think has been addressed thus far: Steels! Medieval steel, while good for its time, isn't that great compared to more modern steels, since it was little more than layers of carburized iron; very labor-intensive to produce, since it requires a skilled smith who knows exactly what he's doing. It's possible that your Medieval-equivalent society has developed better steel-making techniques; perhaps crucible steel (first patented in Europe in the 18th century, although present in Asia for much longer) has made an early appearance. [Answer] Since other non-metallic materials were brought to the subject, you have different fibers that are protective; e.g., cotton, especially against bludgeoning damage, but also piercing if specially manufactured. But even better is hemp fiber, from which bulletproof clothes are made today. You have copper/gold alloys that were made for mining in cultures with little or no steel metallurgy knowledge (Incas) and for armors for its toughness (Korea). ]
[Question] [ My setting takes place in a densely forested continent, with huge trees and rushing rivers. The problem is that this forest stretches on for thousands of miles, only occasionally punctuated by some ancient ruins. The forest is also populated by 'Keepers', who are sort of like overenthusiastic Ents: They will ferociously attack anyone who they perceive to bear ill will towards the trees. Now, due to the nature of this forest, most of the countries of my setting aren't really countries - They're more like gigantic cities, usually built in such a way that they don't have to mess around too much with the forests (i.e. built tall, or underground, or into a mountainside). Unfortunately, the forest also means that traveling between one city to another would be extremely difficult, especially on foot. So, to alleviate this issue somewhat, I'm thinking of introducing some kind of pack animal to setting, preferably something that can be ridden. Unfortunately, I'm not sure exactly what would work best: I'm toying with the idea of some kind of ram. In summary, what ride-able pack animal would work best in a densely forested area? Edit: Keepers do not attack wildlife that simply eat parts of trees, because they do no real harm and mean no real harm. They do take offense to animals who actively uproot/destroy trees though - hence why there are none of those creatures left. [Answer] Pack goats have been used in real life, so that's definitely viable. However since they would likely eat parts of the trees, that might not be the best idea to keep the Keepers happy... Mules have traditionally been used (at least in the United States) as the go-to pack animal for rough terrain. They're hardy, can handle steep trails and rivers, and can carry quite a bit. I know they're used in several natural parks where vehicles aren't an option, and the US Army uses them in places like Afghanistan. [Answer] I'll stay with my answer from [this similar question](https://worldbuilding.stackexchange.com/questions/9214/what-methods-of-transportation-would-develop-in-a-stone-age-society-in-a-forest/9221#9221), Spiders! Enormous spiders bred big enough to ride on, with broad flat backs for strapping cargo to. They could travel among the trees with ease and when the ground clutter was too tight, they could climb up to more open spaces and then web their way around barriers. [Answer] I have a couple of horses and a mule and the latter is amazingly good at getting around on tough terrain and would probably be the best terrestrial pack animal for the job. However, I think in a forest like this we might need something more arboreal, largely because crossing the ground in truly virgin forest can be exceedingly difficult as the forest floor can become a lattice of intersecting fallen timber slowly mouldering down. Consequently you might want something that was more designed for springing from trunk to trunk or at least a creature with feet designed more for gripping than hooves, which really evolved for open and relatively steady terrain. In terms of pack animals, there are certain characteristics that you need - a certain steadiness of disposition, steady gaits and trainability. For the former I would recommend a herbivore, for the latter a social species. Looking at what evolution has offered in the past, larger animals tend to be more ground-based and if you start adding luggage then having it spring from tree to tree with giant lemurs would probably be impractical, although super-awesome. I would probably think about something like a giant sloth - large, herbivorous animals with gripping claws that would probably be quite adept at moving through this type of environment. Alternately you could consider something bear-like as they have a similar combination of strength and ability to climb over and through difficult forest terrain, although you might find them a little fierce to train- much easier to work with animals that favour flight over fight. [Answer] What about moose? There are examples of semi-domesticated moose, including [Älgen Stolta](http://en.wikipedia.org/wiki/%C3%84lgen_Stolta). ![enter image description here](https://i.stack.imgur.com/fBZR5.jpg) The Swedish king Karl XI (king 1660-1697) even had plans to form a moose cavalry. [Answer] To get mules means you'll need to supply both horses and donkeys. That means pasture somewhere. Mules will carry 150-200lbs reliably, you can put 300-400lbs on a mule (as per USFS - but they're using finer mules) - US Army/USMF goes to 250-400lbs (with 900temp), but they'll begin showing signs of injury after awhile at the higher weight limits (ie: not sustainable for a pack-train). Depending on size, larger your mule the more you can carry. Smaller, finer mules handle rough terrain better. You'll have to provide some fodder, if you're in a dense canopied forest. That's unsustainable logistically over long distances (your whole load gets eaten up by carrying fodder). Running/standing water may or may not be an issue (don't know the specifics of your forest; daily rains that completely soak in to sandy soil to a depth of 100'? rivers? streams?), but it'll need to be available, or you'll have to haul it. If you have to haul it, you're not going very far. Mules like trails, game or human-made. They can do some cross-country stuff over rough terrain, but they don't handle the steepest slopes. Not an issue for the forest. You are going to have to watch the rotten logs and burrows. Burrows are known to trap hooves and break legs, I assume massive rotten logs can offer the same problems, a nice outside crust of hard wood, that won't take the weight and collapses, trapping hooves. Goats get over tougher terrain than mules (ie: they do mountain peaks), and are far less ornery (depending on your mule breed; some mules are almost as nice as goats). They carry a little less (75lbs a side, for 150lbs total (your mule payload also needs to be divided in half for max piece size)), and won't be rideable by any reasonably large human (hobbits is fine). They're more aware of predators. Plus, you can get fresh milk on the trail. Goats can eat anything in the hemisphere they evolved in (destroy poisons/toxins), they run into a few things they weren't evolved for in N/S America, that you have to watch out for. > > Consequently you might want something that was more designed for springing from trunk to trunk or at least a creature with feet designed more for gripping than hooves, which really evolved for open and relatively steady terrain. > > > Like springing from boulder to boulder? Goat's dewclaws prevent slipping, and the hooves are designed for gripping on slippery rock and ice, and they conform with the soft pads to any irregularities (which also increases grip). Split hooves spread force. They handle snow, and mud, and... they don't like crossing water (what?). Goats handle icy mountains to hot deserts - although there are desert breeds and mountain breeds, and they don't do equally well in all the climates. Spiders are predators, not sustainable in a pack-train (fodder issue times 100). Unless of course, your forest is teeming with animal game, all the time. Of course, what keeps your spiders from running away and eating well (if you unleash them for feeding time) or eating a delicious human. Elephants might work, but they need pretty energy-dense food (or to be eating all the time). Also, they destroy trees (knock over to get delicious leaves). [Answer] Deer? Deer tend to live in forests and if reindeer are anything to go by they can be tamed. They live in groups or packs. kind of inspired by the Hobbit film's King Thranduil who lives in Mirkwood (a giant dense forest) and rides a giant Elk. The antlers might be slightly encumbering but this can be bred-out/female deer don't have them(big ones anyway). Deer are also extremely nimble and fast, personally I'd go with them.(Its also a great ideer... Don't judge me.) ![Deer pick was required](https://ichef.bbci.co.uk/naturelibrary/images/ic/credit/640x395/d/de/deer/deer_1.jpg) [Answer] If you are looking for some historic authenticity, you could always use human porters/bearers. The human body is amazingly versatile for the task of getting around in a forest. We can't carry much, but if you get enough of us together, we can get the job done. [Answer] I would agree with deer if they can be bred to carry weights on their back. the antlers actually help as they would keep the branches away from the rider. deer also have a symbiotic relationship with the forest as they prune the trees with their antlers [![Deer can clear its own vegetation, not needing traditional roads](https://i.stack.imgur.com/3yFFI.jpg)](https://i.stack.imgur.com/3yFFI.jpg) Deer can clear its own vegetation, not needing traditional roads [![enter image description here](https://i.stack.imgur.com/h9Bka.jpg)](https://i.stack.imgur.com/h9Bka.jpg) Also, elephants can be used to traverse forests. their usual high food consumption Is less of an issue with abundant Forrest [Answer] I would say over-sized squirrels (or another arboreal species) . They are agile creatures and can run through the tree tops. It could be a wild ride. They would have to be really big to carry more than 1 rider, or 1 riders weight in goods, so they might be used more for messaging and transporting small but important/valuable messages/cargo. [Answer] Well, the forests are not safe to walk through, but what about over it, or under it, or maybe even with it? ## Over the forest You could have some manner of dragon as a pack animal, although I would imagine that would not be ideal as I imagine that dragons should be more of a hero's thing rather than an average person's thing. However, why not create you own animal. Some sort of giant floating sky jellyfish, akin to an [overlord](http://wiki.teamliquid.net/starcraft2/Overlord) in design, but probably not in aesthetics. It should be important for this pack animal to rely on some manner of energy un-intensive flotation/flight, and this jellyfish could have giant Helium organs or something more magical. This would give the giant sky jellyfish immense endurance, as they need no effort to be in the sky, although for larger loads you may require several. ## Under the forest You could have giant underground earthworms that create tunnels under the ground, deep enough so that they would not disturb the roots of the keepers but not too deep as to incur standard deep mining problems, such as ventilation, cooling, and natural gases. Two ways about it could be that this giant earthworms of yore created these tunnel networks deep under the ground a long time ago, but are now either more dormant or gone for some strange reason, allowing the use of horses or donkeys in a normal fashion, walking along the tunnel. The other way could be that your people could ride these giant earthworms as they move through the ground ## With the forest The keepers themselves are not robots right? They are living things, with things that they want, and things they dislike. So, it should not be impossible to be able to train keepers of your own that you could then ride on while strapping your stuff onto it. These keeper keepers would then be a fairly invaluable talent that is very rare, and they would determine what and who moves between the vast tracts of keeper infested forests. [Answer] If mules are not what you are looking for, I would suggest using llama. Using the species, as is, would limit riders to small adults and children (~100 lbs could be carried by largest). However, in a very thick forest, especially one in which low hanging branches could not be removed, riding would not be common. Instead, strings of pack llama would be led by people walking them along the trails winding through the forest. The llama does have the additional value of being a meat animal as well as its hair being useful for weaving. Llamas are also useful as watch animals, often used to help guard herds of other livestock. ]
[Question] [ I have a "simple" question that is the basis for an idea I'm developing: Is it possible to terraform the moon and, if so, what type of technology would be needed? I understand that this isn't the case because of its current state, but, for arguments sake would it be possible to do this if certain conditions were met: an artificial core, some artificially imposed atmosphere, bring water, life and vegetation, etc. For clarification: The terraforming would need to be man-made and be able to sustain humanity as it currently is from a biological sense (no additional breathers, pressure suits, etc.). This means that there would need to be some form of green plants, soil, water, free moving air, gravity, and the ability to grow plants and raise animals. [Answer] Short answer... no. Longer answer is, it depends. The biggest restriction I see is lack of atmosphere. Just supplying it with an atmosphere is a short term solution as, by itself, the moon doesn't have sufficient gravity to keep an atmosphere from leaking into space. This particular question was asked on another site: <https://physics.stackexchange.com/questions/52527/can-low-gravity-planets-sustain-a-breathable-atmosphere> Quoting from one of the answers: > > The escape velocity at the moon's surface is about 2.4 km/s. The mean > speed of oxygen at 293 K is about 0.48 km/s. > > > A commonly quoted rule of thumb says that the escape velocity needs to > be 6 times the gas's mean velocity in order for that gas to remain > captive to gravity and the values I quoted are related by a factor of > only 5. The air would contain water (since dry air is very > uncomfortable to breath) and carbon dioxide (as a by-product if not > also needed to sustain the cyanobacteria/plants you would want in > place of planetary size mechanical carbon dioxide scrubbers, then > there are the nutrients you would need to sustain those) which would > readily exacerbate an atmospheric greenhouse effect and, with the moon > being at about the same distance from the sun as is earth, you would > expect the air to warm up to similar to earth temperatures, though > without the moderating effect of oceans, and so cause the oxygen to > dissipate. As nitrogen is lighter it's mean speed at the same temp is > higher, v\_rms something like 0.51 km/s IIRC, so it too would dissipate > as would water vapour. > > > In short, it doesn't seem likely that it would be possible on the > moon. > > > But, since you mention an artificial core of some kind, maybe one that creates an higher than natural gravitation effect, that could be circumventable, if it justified the cost of drilling to the core of the moon to install the device. [Answer] ## Yes With several caveats. ### Volatiles As @Saidoro mentioned, you need to introduce all the volatiles required for life. This includes atmosphere, hydrosphere, and Nitrogen. It's easy to find enough water and oxygen in the various ice moons and comets throughout the Solar System. However, compared to the amount needed, nitrogen is pretty rare. You'll need to expend some thought about how to get enough. ### Longevity As you can tell by looking at the Moon, the volatiles won't stay around the Moon over geological ages. So if you do provide the Moon with volatiles, how long can you expect them to stick around? There are many [Atmospheric Loss Mechanisms](https://en.wikipedia.org/wiki/Atmospheric_escape). Unfortunately, only one of these (Jean's Escape) is easily calculated. [Wikipedia has an excellent and scientific chart](https://upload.wikimedia.org/wikipedia/commons/4/4a/Solar_system_escape_velocity_vs_surface_temperature.svg) showing different body's ability to retain an atmosphere over geologic ages. [![enter image description here](https://i.stack.imgur.com/iHuco.jpg)](https://i.stack.imgur.com/iHuco.jpg) However, I've created my own chart based upon Jean's escape. I apply a "fudge factor" to cover the other escape mechanisms and it gives the [half-life](https://en.wikipedia.org/wiki/Half-life) of different gases around a given body. Be aware that my chart assumes that the body has a thick atmosphere to begin with so certain loss mechanisms such as [sublimation](https://en.wikipedia.org/wiki/Sublimation_%28phase_transition%29) and [sputtering](https://en.wikipedia.org/wiki/Sputtering) aren't an issue. According to my chart, you could expect water added to a thick atmosphere around the Moon to have a half-life of around 200,000 years. A very long time compared to human civilization. A very short time compared to geologic time. Half-life of gases around major Solar System bodies: [![Half-life of gases around major Solar System bodies](https://i.stack.imgur.com/1Qf21.jpg)](https://i.stack.imgur.com/1Qf21.jpg) Measured in years Notes: 1. Any half-life with a value of $\cdot 10^{98}$ is a liquid or solid at the conditions on the surface of that body. Meaning as long as it is surrounded by an atmosphere, there will be no loss of this compound (the reality is that airless bodies will still see some losses). 2. The body Ceres is just outside the [snow/frost line](https://en.wikipedia.org/wiki/Frost_line_%28astrophysics%29) based upon my calculations. 3. When I could find them I used melting & boiling points for 0.1 atmosphere pressures. When I couldn't find those I used those for 1.0 atmosphere. 4. Tweaking the fudge factor is tricky. Tweak it too high and Mars gets too much atmosphere. Tweak it too low and Titan doesn't get enough. I think I found a happy compromise since Ganymede doesn't get any, Titan has one as long as there's some replenishment, and Mars lost most of its atmosphere. 5. Red background means half-life < 100,000,000 years 6. Yellow background means half-life < 4,500,000,000 years 7. Green background means half-life > 4,500,000,000 years 8. White background means substance isn't a gas at those conditions [Answer] I like all the answers above. One possible method would be to build an envelope around the moon. This is an alternate to giving the planet an entire atmosphere, which it would periodically lose and need replenished, but it's still a gonzo engineering feet and the envelope would be subject to regular meteor strikes and punctures. It would need regular repair, or perhaps, some self repairing technology and leak plugging - that's no simple task. Another method, which I like, would be to dig a very deep hole into the moon and have a kind of deep underground dwelling, with big fans to enable circulation and mirrors to reflect in sunlight. As an earthly example, the Dead Sea is some 400 meters below sea level and as a result, it's atmosphere is about 5% more pressure. [Source](https://en.wikipedia.org/wiki/Dead_Sea#Climate). On the Moon, with 1/6th the gravity of Earth, well, calculating it gets ugly, but if you dig a hole, some, 30-50 miles into the Moon's surface, perhaps at a steep incline to avoid direct sunlight but still take advantage of reflected sunlight. It might be possible. Something, kind of like this but about 500 or 1,000 times bigger. [![enter image description here](https://i.stack.imgur.com/z0WYK.jpg)](https://i.stack.imgur.com/z0WYK.jpg) The hole or whatever you call it (Atmosphere well?) should requires far less replenishment of atmosphere than the surface terraforming idea. There would still be some, you'd need a light atmosphere around the entire moon to avoid too much loss and preserve most of the atmosphere in the deep hole, but it's more feasible than making the surface habitable. Another alternative, with enough energy would be to generate to Oxygen directly from the silicate material of the moon, so the oxygen would be generated from within the hole. Digging deep into the Moon might provide water sources and other minerals as well. I'm not sure anyone would want to live in a hole, but it beats living in a pressurized suit, never going outside. [Answer] Yes. An atmosphere would need to be introduced(likely through comet bombardment or the like), and some (probably biological) machines would need to be introduced that could turn moon-dust and oxygen into something that earthish plants could grow in. Additionally, a few changes would need to be made to the animals and plants who would be living there, most notably adaptions for the decreased gravity and atmospheric pressure and for the increased radiation caused by the moon's lack of a strong magnetic field. Once the technology to do all of that is available, the moon will be terraformable, and will likely be one of our first targets for doing exactly that. [Answer] Terraforming is a beautiful, and ridiculously simple principle, that is more than godlike in theory. There are, however, two major issues that limits the amount of terraformable celestial bodies to a very small number: * Magnetic field. We, here on Earth take its existence natural, but it has a huge role in the fact that life here is so much more pleasant. I don't know, but am 100% sure Moon has no such a magnetic field Earth has, so its surface is much more exposed to solar wind, gamma rays and such. These can even change the chemical composition of a theoretical atmosphere. Whether Earth's field reaches the Moon, and thus provides some minor defense is beyond my knowledge. * Gravity. Attracting force of Moon is only 1/6 of the Earth. This is a huge difference, and because of it, Moon would be unable to support such a layer of gases. It would simply leave that. Without gravity, there's no atmosphere. Without atmosphere, there's nothing. What can you do then? I prefer the idea of building domes, then building more domes, with their own gardens, greenhouses and other life-supporting facilities to produce oxygen. Then, it might be exposed to the lunar surface as an attempt. Or, if possible, building extremely huge domes, that might be able to support clouds and rains within! Very partial solution, but I can see the outcome of it. Source: [SpaceEx.SE](https://space.stackexchange.com/q/634/306) [Answer] I agree with [@Random's answer](https://worldbuilding.stackexchange.com/a/3369/760) about the Moon having insufficient gravity to hold onto an atmosphere in the long term, so it would have to be continually replenished. There's other important considerations for terraforming the Moon (and Mars): low gravity and the lack of a magnetic field. The Moon lacks a magnetic field. Space is a harsh place, but Earth's atmosphere and magnetic field protects us from most of it. Lunar inhabitants will be exposed to cosmic and solar radiation. I don't have a radiation exposure map for the Moon, [but I do have one for Mars](http://www.space.com/21353-space-radiation-mars-mission-threat.html) where you'll be recieving a dose of about 0.25 sieverts per year. [1 sievert is a 5.5% increase in cancer risk](https://en.wikipedia.org/wiki/Sievert) so the lunar population will have a very increased risk of cancer. This can be mitigated somewhat by adding certain molecules to the atmosphere, such as ozone, to block solar radiation. Cosmic rays are unpredictable and difficult to block without a powerful magnetic field. Solar flares can be predicted and lunar inhabitants will have to take to shelters. Then there's the problems of living in a low gravity environment. Everything we know about human health says [this is bad for humans](https://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_human_body) who have evolved for billions of years to take advantage of a constant gravity. The biggest long term problem is [a loss of bone and muscle mass](https://en.wikipedia.org/wiki/Spaceflight_osteopenia) and a tendency for bodily fluids to pool in the upper body. There's no long term cure of this. [Answer] Others have noted with up-to-date caclulations that the Moon would hold on to air long enough to be useful to people settling there, were it to be introduced. That confirms the assertion made in a story I recall, about a near-future society (no super-duper tech) that co-opted a mission to redirect a comet, and had it crash into the Moon instead of just missing. The story ends with the appearance of a fuzzy look to the moon, with everyone excited at the potential. Another story I recall featured moons of Jupiter (I think), where the first one done just has added air which needs a bit of topping off from time to time, but the later ones have a membrane to keepmthe air in. In Wil McCarthy's Queendom of Sol series, the Moon and other small bodies were [crushed](http://rads.stackoverflow.com/amzn/click/055358717X) to give them a smaller diameter and higher surface gravity. In his novels, industrial nutronium marbles are a thing, and whether he supposes gravity holds it together stably or some other finishing treatment is needed is not explained. However, the late Robert L. Forward covered the topic with the intention of being "hard" sci-fi. An asteroid layered with carbon and a shaped charge (of anti-matter) produced a collapsed-matter disk encapsulated in diamond strong enough to maintain the internal pressure. ]
[Question] [ Quantum physics today tells us that we may not predict outcomes with certainty. We perceive events as random. So is this old philosophical fantasy of an all knowing computer possible? Meaning that all particules at a time T would have a determined state. If it is, and assuming that there is going to be some randomization to go from T to T+1, how precise of an estimation could we get of the future? * can a weather forecast for the next day be 100% reliable? * can we answer questions like "if hitler had died as a kid" with 100% reliability? * how much further could we predict from T, with good accuracy, knowing that there is randomness? [Answer] [Maybe. Maybe not.](http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics) People disagree about determinism. However, you don't need quantum mechanics to see that such a computer is not going to work. Suppose you've constructed a computer that can store $n$ bits of memory. Then you'll need those $n$ bits to track their own state. You've got no memory left to track the rest of the universe. If you use any of the bits to store the state of the universe, you become unaware of your own state. By choosing a suitable approximation you might end up having reasonably good information about everything. At this point, [chaos theory](http://en.wikipedia.org/wiki/Chaos_theory) comes into the picture. That's a big topic with some interesting results. I don't recall the answers to your specific questions off the top of my head, but the general answer is that even without randomness, there are things you're just not going to be able to predict given finite information. --- A little more detail about the compression issues. Suppose you live in a very technologically advanced world and you build computers for a living. At some point, a physicist comes to a great breakthrough: the world can only be in one of $2^n$ possible states. That's the number of ways the atoms (or quarks, or fundamental Lego pieces...) in the world can be arranged. You immediately decide to build a computer that can store which of these $2^n$ states you are in and then compute the next state you'll end up in. To distinguish between $2^n$ states you need $n$ bits of information. Any less, and you'll end up being unsure which state you are in. Thus, knowing exactly how much memory you need, you go ahead and build it. Suppose you've managed this task. At least, you've managed to build your $n$ bits of memory and they work: you've checked you can store all the necessary values. That means that your computer's memory alone can take on $2^n$ states. If the physicist was right and the amount of memory you made was enough, the state of your computer's memory completely determines the state of the rest of the universe. You're not going to be able to calculate much with that.) (Interestingly, if this computer exists, it must exist in all $2^n$ states, meaning it already existed when you started building it.) [Answer] Given a sufficiently detailed model of the universe, and a sufficiently fine-grained time step, you could get pretty close from a macroscopic point-of-view view. However, once you look at small enough scales you're going to have a problem... The Heisenberg Uncertainty Principle [forbids knowing](http://en.wikipedia.org/wiki/Uncertainty_principle) the exact state of the universe at any given time. This is not simply because observing a particle causes it to change (although that is part of the problem). Instead, it is a fundamental property that arises from the wave-like nature of matter under quantum physics. The most well-known (but not the only) formulation of the uncertainty principle says that the product of the uncertainty in position and the uncertainty in momentum must be greater than a certain threshold. The more precisely one is known, the less precisely the other is known. It may seem like these small changes are insignificant, but chaos theory demonstrates that seemingly insignificant differences can potentially lead to vastly different results. For example, a small change in the velocity of an Earth-bound spacecraft could lead to it skipping off the atmosphere to be lost in space, or burning up in the same. [Answer] > > So is this old philosophical fantasy of an all knowing computer possible? > > > No. Information theory dictates that this is not possible. If you accumulate up all of the bits of information that define the universe at a given instant of time, all of the states of those particles you get some giant number N. How are you going to store that information? Information theory says (in short) that to store a universe's worth of particle state, you need a universe worth of particles to store it. A particle already represents the entirety of its information (position, composition, velocity, angular momentum, etc, etc). The only way to store that same information in less storage is to lose information via encoding (assuming that the nuclear arrangement of atoms are identical to others of the same element for example). So ignoring the whole 'can you predict state based on existing state' question - you can't even get the whole existing state in the first place. [Answer] Yes and No Quantum mechanics is full of probability. You simply can't get around it. You can never know for sure if a particle at time $t$ in the future will be at point $A$ or point $B$. Quantum mechanics forbids it. Sure, the odds could be essentially 100-to-1 against that it will be at point $B$, but there's still a chance that it could be there. So there will always be randomization. However, there's a scale where this doesn't matter a lot, and that's on the macroscopic scale. Yes, there's a chance that a baseball hurtling towards you will move an inch to the left for a split second, but that would require every single particle in the ball to move one inch to the left. Once you combine all those wavefunctions, you find that that is really improbable. So if you want to make a large scale simulation, you can sort of ignore that. That's one reason we didn't really think about probability being extremely important in physics until we could work with tiny particles, because the effects didn't show up on a macroscopic scale. So while you can't predict the minute details of each particle's motion, you can model the ball fairly well. [Answer] Sort of. Quantum particles can exist in multiple states simultaneously. When they interact with other particles they then collapse into one of their possible states, with there being no way to know for certain which they will collapse into in advance. If you're looking only at quantum particles you can't predict even one interaction into the future with absolute reliability. However, this clearly doesn't give the whole story. A baseball contains an uncountable multitude of quantum particles, each interacting with other particles and constantly collapsing into various states, yet any child can predict the path of its movement in spite of that. The explanation for this is that as you add more quantum particles the system they describe becomes more and more deterministic as the probability of some significant portion of the particles collapsing into a possible but unlikely state approaches zero. We humans are made of so very, very many quantum particles that the effect of quantum randomness on our behavior is negligible, we are for all intents and purposes entirely deterministic. The weather tomorrow could be predicted with near-perfect accuracy provided one knew everything there is to know about the current state of the Earth's atmosphere and any nearby objects. The current state of the human world if Hitler had been killed as a baby could be predicted with near-perfect accuracy provided that one knew everything there is to know about the state of the world prior to Hitler's birth and all ensuing events. However, either of those predictions is well beyond our computing capabilities for the foreseeable future, much less our data-gathering capabilities. [Answer] Disclaimer: My science levels are all over the place so this may not be 100% accurate. I'm specifically concerned about my first paragraph which is a alternative interpretation of Gödel's Incompleteness Theorems. It takes a different view on the matter, one that I feel is correct but am not certain of. I added a second concrete example to illustrate the thought process. Slightly unrelated is Turing's Proof which rankles me and may be related to decoding the universe. See Note2 for an argument on Turing's Proof that I way more certain of than I am of my argument on Gödel. Our current math theorems only tells us that we can never have a complete system in the sense that we can never know with certainty that our axioms and such are complete, etc. But this rides on the assumption that the parts our math doesn't allow us to grasp aren't the ones that override this assumption. (Our current axiom set roughly says "You can't have all the rules because you can't logically get to some of them, no matter what set of axioms you pick" but there may be a rule that we have to hit by chance or take on faith, since we can't get to it logically by our current axiom set per Gödel, that translates out to roughly: "Disregard all other rules. The last axiom of math is the 5th item on your shopping list on every billionth day. Just take my word for it."). Like all science we may discover that we need to rewrite the axioms when we hit new areas of math. This could open the way to us discovering the true set of axioms that explains all (if they exist). That is, by virtue of logic failing we could potential be forced to have our minds wander until we hit the right answer by chance (which sounds a lot like the current state of affairs for our current search for a [ToE](http://en.wikipedia.org/wiki/Theory_of_everything)). A good example for the possible last axiom (well, maybe for a moral system and not a mathematical one) would be the rule: "Everything is a grey-area of some extent, there are no black and white rules." which seems decent if you can apply it to just about everything. But when you get around applying that rule to itself it becomes a statement of "Sometimes things are black and white, because this rule is a grey-area itself." So do you edit it to "Everything is grey except for this rule." or do you take it as it stands or do you toss it completely. The right course of action seems difficult. Assuming that this is one of the true axioms of the universe the two framings have different outcomes: strict rules with a loophole written in (that may or may not be exploited by the universe at any given moment), or with exceptions only for themselves. Either way its status as an axiom relegates it to the "take it on faith" principle which in the case of this self-paradoxical rule is a little harder to swallow that 1+1=2. So even if the universe is deterministic to a fault we would most likely need a lucky guess or a change in mathematics to get all the rules right. It could be that even without perfect rules we could move towards a snapshot of the universe at time T. Our certainty would never reach 100% but we could get very very close. If your predicting the future accurately left and right though, then you pretty much don't care if you're 100% right, you might just assume you are spot-on which is basically what Bayesian statistics would tell you. Sure you missed that thing-a-ma-what's-it axiom, but that only causes a simulation glitch once every billion years... Do you care? If the universe is boot-strappable from a small set of data and has implicit T states, then we could operate on all of this data and recreate a time-location-state(which is what you're asking, so this is the caveat). The simulation could even reduce as far as a random seed number. This may be a number with only finite possibilities. We could test the parameters until we reached one that modeled our current T value correctly. This would get us to the point of modeling the universe without violating the Heisenberg Uncertainty Principle or any other building blocks. If the universe fails any of these assumptions (is not deterministic, etc.), then our math can give us possible futures with error measures. You could extract information as long as your signal-to-noise ratio for the universe was relatively decent. Non-implicit universes would have diminishing returns on the signal over time and increased noise (which would model our heat as information loss perfectly!). Note: Figured I'd add that our current science makes the needed assumptions when it assumes to know the effects of the constants on the universe. "Our Constants are so finely tuned it must be the work of an intelligent design". What gets more in the way is the problem of storing a given snapshot of the universe so that we can compute on it. If there isn't a small boot-strappable data set then it can't be done. There are various physical effects that operate as a whole and not additively, so you would need an atom to record all the information about that atom, etc. resulting in the universe. Otherwise you'd need a frequent snapshot of the area of interest to work off of. If you could acquire a frequent snapshot of an area there becomes little need to forecast very far ahead which reduces the error we can have in T+1 allowing more inaccurate rules. (Our weather forecasting is an example. Snapshots of poor detail are acquired and a simulation plots out 7 days. Days closer to the start of the simulation are more accurate. Increasing resolution, simulation frequency, or computing power increases accuracy overall). Note2: So this isn't directly related except for the fact that if I'm right all of a sudden we can compute Chaitin's Constant which will probably give us a decent platform to create our boot-strappable data set (it also flirts with violating [Gödel's Incompleteness Theorems](http://en.wikipedia.org/wiki/G%C3%B6del%27s_incompleteness_theorems))... So Turing's Proof has always rankled me because it amounts to saying "If you give me a program H that computes Halt() I can give you a program B that always invalidates H" the problem is that his formulation involves B containing H which amounts to saying "I can construct a wrapper function/super-set to H that invalidates it" so the implicit assumption is B is always bigger than H. You can in fact (I wrote a proof) construct an H that uses B to expand itself recursively. This makes sure H is always able to get the correct solution for Halt() as long as H is at-least 1 bit larger than B. If you extend this out to infinity then technically Turing's Proof is right because both H and B will end up at the same infinite size and we can't decide when their the same size (at-least my function can't, although it would be possible if you made a quantum extension of my algorithm (but that may give B new tricks of subverting H as written)) so we end up with an infinitesimal fraction of all programs that are undecidable. But that just means your constant has an infinitesimal error and so is still usable for our purposes. Edit2: Oh yeah your questions... * How precise of an estimation could we get of the future? It depends, see the other answers. * Can a weather forecast for the next day be 100% reliable? I'm pretty sure we can already do this, we just don't run them every day. It's run the minimum amount of times for tolerable accuracy because weather "people"/stations pool money to run a simulation on a supercomputer (or they did anyway...) * Can we answer questions like "if hitler had died as a kid" with 100% reliability? If we achieve exactly 99.999% accuracy in our rule set for time-steps of 1 yr (noting we'll never reach 100% unless we just take it on faith and it turns out to actually be our magical rule set) and get a perfect snapshot today (2014) then your looking at 99.874% accuracy on our Hitler predictions. So no, not 100% at that point but pretty damn close. * How much further could we predict from T, with good accuracy, knowing that there is randomness? Well if you compute Chaitin's Constant for your universe you can actually predict your randomness given enough bits of information (this is exactly the same as predicting the seed of a random number generator given x bits where Chaitin's is your seed and the rule set is the generator. You tweak things snipped long explanation until your correct and then randomness doesn't matter). If we take the other track and assume you can't then you have the same situation as for the Hitler situation. The perfection of your rule set determines how close you can get. You multiply the accuracy every time-step (so starting with .999999999999 you lose 1 off the least significant digit each step and there are Z steps each second which is at least the speed of light divided by the number of planck lengths in a meter in magnitude (so 1.855492(18) x10^43) which means for an accuracy to the 12 decimal place you lose at least (.999999999999 accuracy to the 2 x10^43 ticks/sec to the 31600800 sec/yr) .2% accuracy each year (I think I did that right...)). So if we place our limit for good accuracy at 90% then we have 50 years. [Answer] depends It is theoretically possible to completely observe the state of a universe at time T, and predict its state perfectly at time T+1. Because our models of the universe are models, they usually assume there is some source of perfect state to be had. Issue #1: Current QM theory suggests that it is not possible to measure all of the perfect state of our universe at time=T. There must be information missing (see Heisenburg Uncertainty). However, nothing exists that says QM is the final model of the universe... there might be a way for all we know. Issue #2: If you try to predict the universe while still inside it, you run into funny issues. In a very long story short, the fact that your model of the universe has to include a model of your computer, your universe is at least strong enough to do integer arithmetic. This instantly puts your universe (and its model) under the control of Kurt Goodel's incompleteness theorem. Handwaving the math terms, it means you will have to accept at least one undesirable trait to make your computer a reality: * The model must be incomplete, failing to model at least SOME part of the universe * The model must be inaccurate, getting the state of part of the universe wrong * The model must be illogical, failing to follow the rules of First Order Logic * The model must be non-enumerable, unable to ever actually be contained on a sheet of paper (or on the hard drive of a computer) * The model must be unprovable, so you THINK you have the right answer but have no possible way of proving it Unfortunately, by the rules of integer arithmetic and First Order Logic, that's the breaks. It is only feasible to predict the universe using a computer outside the universe because of this issue. [Answer] Is the predictor located inside the universe? If so, no. Thomas Breuer [has proven](https://homepages.fhv.at/tb/cms/?download=tbPHILSC.pdf) that universally-valid deterministic or probabilistic theories are impossible. What does it mean? It means that an observer cannot measure his own quantum state (wave function, or probability). Maximum what he can measure about himself is possibility which is more lose thing. Thus he cannot predict even probabilities for the future. If you predict future possibilistically, you can say very little about it, only that some things are possible and other are impossible. In other words: If the predictor is inside of universe: * Deterministic prediction is impossible * Probabilistic prediction is impossible * Possibilistic prediction is possible If the predictor is outside the universe: * Deterministic prediction is impossible * Probabilistic prediction is possible * Possibilistic prediction is possible (because probabiblistic is possible) [Answer] No I agree with the information-theoretic and Heisenberg answers outlined above, but haven't seen anyone bring up the Halting Problem objection. Here's the Halting Problem: Is it possible to write a computer program ORACLE that will look at another program FOO and the inputs BAR that program will receive, such that ORACLE will say with 100% accuracy whether FOO will terminate if given BAR? The answer is no. This is not possible. The reason why it's not possible is applicable in other contexts (including here) so I'll give the proof. In short, if I have such an ORACLE, I can write a program S (for smartass) that calls into the ORACLE, and then does whatever the opposite of what ORACLE claims will happen. Predicting the future runs into this exact problem: Unless it is literally impossible for someone to build another, then other people will have predictors. If they're good at using them, now they know what you think they're going to do. It won't be hard for them to find clever ways to screw around with you by deviating from those predictions. [Answer] No. Any system with three or more independent variables will be chaotic. That does not mean not repeatable, but it does mean that the only way to determine the outcome is to run the process to its end condition. See "Period Three Implies Chaos", by Tien-Yien Li and James A. Yorke, published in The American Mathematical Monthly Vol. 82, No. 10 (Dec., 1975), pp. 985-992 Link: <https://www.jstor.org/stable/2318254?seq=1#page_scan_tab_contents> ]
[Question] [ Dragons are often depicted with a set of plate-like scales along their belly like a snake. In snakes, this adaptation is to aid in their slithering locomotion. However, dragons don't slither; they have large legs and wings for walking and flying Is there some other function that could justify snake-like scales on the belly of a quadruped like a dragon? [Answer] The same reason for which the crocodiles have plated bellies, in spite of having legs able to walk - the conformation of their legs aren't keeping the body clean of the ground all the time, on the contrary - most of the time their "walk" resemble crawling more than actual walking. Even more so as the "usual" habitat in which the dragons are depicted are mountains with sharp peaks - denoting a material that is hard, brittle and prone to fragment in shards ([medium grained oriented in such a way that the rock is easily split into thin flakes or plates](https://en.wikipedia.org/wiki/Schist) in geological parlance. Or some other forms of volcanic origin). --- If you like this better: evolution favoured dragons with plated bellies simply because the individuals which didn't get one were slain by heroes before they were able to reproduce. [Answer] The simple answer is protection. For one, those heroic dragonslayers running around would dearly love a dragon with a vulnerable belly: one good stab with a spear, and the dragon is probably dead. This is doubly relevant when one considers that with the typical large dragons, the stomach is the easiest target to reach and (depending on size) possibly the only target that can reasonably be struck with melee weapons, unless the dragon is so generous as to wait while the slayers grab a ladder, prop it up against the dragon like they're about to do some work on the roof, climb up towards the head or back... no, I really don't see any sane dragon being that nice. Having scales on the belly would actually be more important than most other points on the body. If you want to stick with evolution-based reasons from before humans come into the picture, the logic doesn't really change. Belly scales shield one from any rude animals stupid enough to try and ambush the dragon (like some killer venomous snake, ironically enough), or as Adrian Colomitchi notes in his answer, dangerous terrain. It would admittedly be hilarious if a dragon slipped when a rock cracked under its foot and impaled itself on a stalagmite or something, but in general any dragons trying to use potentially cramped caves or tunnels are going to want scales to avoid gashing themselves frequently on any sharp rocks; it doesn't have to be fatal to be a serious concern. If your dragons are prone to fighting with one another (or if there are other creatures big and nasty enough to compete with them, like griffons or giant eagles or some such), belly scales also shield them from the claws of those enemies. Gut wounds are often at least temporarily crippling if they get past the outer tissues, and in nature you don't typically have the luxury of antibiotics, time to recover fully from disabling injuries, etc.; a predator with a wound like that is most likely dead within the week, since a torn liver or stomach is definitely going to spoil its hunting prowess, setting it up to starve to death unless it's very lucky. A layer of scales on the belly to match those on the rest of the body (I'm assuming the standard scaled dragon here) would be only natural to have. Bonus points if dragon courtship rituals tend to the savage, requiring protection just to keep from maiming one or both dragons, but that's probably redundant on top of all the other reasons. Frankly, dragons seem likely to have scales on their bellies if they have any scales at all. The better question to ask, in fact, is why so many dragons have scales everywhere but on the area in greatest need of them! [Answer] ## For the same reason stegosaurs have armorer throats, for defense. [![enter image description here](https://i.stack.imgur.com/1eLGF.jpg)](https://i.stack.imgur.com/1eLGF.jpg) Stegosaurs have flexible necks so armor plates have to be small, but if dragons are like dinosaurs their torso is rigid so armor can be as big as possible. You see this in crocodiles which can be attacked from below, armor plates on the belly are as large as possible without impairing movements. An animal that can fly is going to face many attacks from below, it may even be more heavily armored on the belly than the back. [![enter image description here](https://i.stack.imgur.com/x2I1h.jpg)](https://i.stack.imgur.com/x2I1h.jpg) [Answer] Dragons fly[citation not needed], and any observer can see that the wings of the average dragon are not going to cut the mustard for unassisted flight. Dragons also breathe fire[citation not needed], which requires a source of ignitable liquid or gas. Both these functions are served by the dragon's digestive system, which releases hydrogen from its food and stores it in a sac in its abdomen. The sac provides bouyancy to compensate for the dragon's weight/wingspan deficiency and also fuel for its fire. This sac will, obviously, inflate extremely rapidly after a substantial meal of, for example, heroes, hobbitses, suitable rocks (trolls) or anything else it can get its claws on and therefore needs to be constrained by something even tougher than regular dragon skin; also the sac must not be unexpectedly vented (by, for example, a lance or arrow) unless the dragon really wants to risk cooking itself and everything else within a hundred yards or so. Both these requirements have led to overlapping armoured plates around the dragon's belly, all the way up to its throat and mouth, which is usually the ultimate discharge point for the hydrogen (flatulence is only used for short-term acceleration; an after-burner, if you like). Simple evolution in action, nothing to see here. [Answer] Dragons normally show a complete lack of respect to the square cube law by existing as they're portrayed, so by all means, a dragon does not conform with the laws of this world, being able to seemingly ignore the natural constraints of biology through yet unknown means (something many would call "magic") and thus don't need to worry about the problems that should normally come from being too heavy. for that reason, being more well protected is inevitably an advantage for them, especially in a place like the belly, where, as far as other living creatures go by, tends to be a fairly vulnerable and important spot in comparison, especially so for a creature that's usually flying around with its belly always on display to any crazy Enough bowman or ballista operator with a black arrow and a "go get em" attitude (and also incredible strength) to aim and shoot at. At the end of the day, the various evolutionary approaches to increase survival rate we see in the real world come each at their own price. Being able to fly means you're normally not sturdy when compared to a non-flier of similar size, and your size will be naturally limit so long as you're not willing to sacrifice that. Higher defense usually means more weight and less mobility. A larger size means more protection at the cost of more food, while a smaller body grants better mobility and less defense against larger creatures. However, from the moment the catch that comes with those trade-offs is flung out the window, the most successful organism will the one that, like a dragon with treasure, hoards them all to become the closest thing to a borderline unkillabe monster. The dragon's incredible success can be tracked essentially to its ability to go against the laws that bind every other organism, since they can afford to be big, tough, agile, still able to fly, energy-efficient and disproportionately strong, because all of those cost exactly zero evolutionary drawbacks to it. These things only need to worry about starving to death, diseases and old age, and that middle one assumes they don't also have a superb immune system like some creatures on earth. Summing up: why would they? Because they can. The dragon's negation factor means it's own evolution of is much closer to the evolution of technology and warfare than it is to normal biological evolution. You're either stacking up more capabilities and further developing those you already have like a powergamer's character or you'll end outcompeted by others of your kind. [Answer] In J.R.R. Tolkien's legendarium dragons have soft unarmored bellies and so some of the largest and most fearsom dragons were killed by puny men stabbing them in the stomach area or shooting them in the breast area. That is how some of the most famous dragon slayings in the legendarium happened. And I have reason to believe that those dragons were so large that when they stood up straight on their legs their bellies would have seen so high above the ground that someone would have had to jab straight upwards with a long spear to reach them. And maybe Tolkien's dragons always crawled along the ground in battle, with no space between the ground and their stomachs for any enemy to stab them. So the only places where an enemy could stab or hack would be the sides and the tops of the dragons, protected by armored scales. So maybe Eru could make Morgoth think the dragons didn't need any armor on their unndersides. But of course that is inconsistent with how Azaghal stabbed Glaurung at the Battle of Tears Unnumbered, so apparently Tolkien's dragons didn't aways press their undersides against the ground for protection in battle. So it always seemed like a major design flaw that Tolkien's dragons had such vulnerable unarmored undersides. How could Morboth have been stupid enough to design dragons with such fatal flaws? And of course the answer could be that Eru made Morgoth fail to see the fatal design flaw, because Eru wanted to make it possible for great heroes to slay dragons. But if a writer doesn't specifically want to make it possible for a great hero to slay a dragon in his story, because he is telling a diffrent type of story, then they have no need to give their dragons vulnerable, unprotected undersides (or unprotected sides, tops, tiny spots right above vital organs, etc.). Possibly when a dragon attacks an army, or an army attacks a dragon, in a story, the dragon can walk over the army formations, with their well armoured underside 20, 30, or more feet high, and out of reach of their enemeies, and then suddendly fold their legs and come slamming down on the soldiers below, crushing tens or hundreds to death, with vertical spears and swords snapping like toothpicks. That would crush the hopes that any character might have of being able to stab the dragon in the soft underbelly. And also crush the character if they were under the dragon at the time. [Answer] Breeding War dragons have been selectively bred by warlords and kings, for thousands of years. War dragons descend from free dragons that had (some) belly armour. For free dragons, heavy belly armour would only add weight and limit flying. It has hardly any evolutionary advantage. But in a war involving humans and dragons, the dragons have a great advantage, when they have plate-like scales along their belly, it makes them invincible for arrows, spears and swords. ]
[Question] [ Human beings contain mana, which is the energy required for life. Mana grows over the course of a person's life, being released at the moment of death. Demons can feed on this energy to increase their power through the creation of pacts with humans in exchange for magical power. When a demon makes a pact with a witch, the human is rewarded with a boon that allows them access to spells. In exchange, her soul goes to the demon after death. The number of souls a demon can collect, the more it can increase its own power. This competition between demons for human souls culminated into many wars and much bloodshed among witches, which led to the detriment of everyone. To end the wars in the human world, demons agreed to a treaty amongst themselves. Instead of warring with each other for a piece of each others pie, they would share the spoils. Witches would be divided up into families called covens, each with their own patron demon. When a witch came of age or joined the family, they would sign a pact with that coven's specific demon. She would gain access to magic in exchange for her soul. Each pact is an investment for the demon, which places a seed of their power into the individual. As their Mana increases with age, the seed grows in tandem. When the witch dies and their soul is claimed by the demon, the seed has multiplied in strength, returning on the demon's investment tenfold. Through this method, a demon would be guaranteed a steady stream of souls as the coven expanded either through birth or recruitment. This business model soon produced flaws however. It didn't take long for demons to realize that increasing the number of witches in their family as fast as possible was in their best interest. This led to a massive increase in recruitment, as many individuals among the population would simply be inducted into these covens. Potential witches were eager to sign away their souls in exchange for power from a patron, and demons were just as eager to collect more souls than their rivals. This led to a race to the bottom, as covens lowered their standards to try to outdo other covens, creating a generation of crappy witches. What I want is for demons to value producing witches of high quality and skill, rather than turning covens into basically recruiting centers. However, it is natural for standards to be sacrificed in the name of producing content if the latter is in one's best interest. This is similiar to the streaming wars, in which most of Netflix's movies and series are crap, but it is made in such high quantities that they outpace the competition. How can I make this happen? [Answer] Adding to Matthew's excellent answer, throw in a risk factor to sweeten the value of existing vetted witches over untested recruits. For example, imagine that a demon must invest three unit of power into a potential witch just to give her the possibility of reaching mediocre level, but that there is a 75% chance that she will fail to achieve that lowest fruitful proficiency, loosing the entire investment in the process. Additionally a proven mediocre level witch is assured of achieving the one hundred fold return level of mastery for only one unit of power each year for a decade. In such an environment, demons might invest some of their power in recruiting new potential witches, but only when they have power to spare from nurturing their proven crop. That more conservative method is their only real hope for consistently rising in power. [Answer] I'm half tempted to post this as a comment, because it's obvious, but... Make "mana return" correlated to skill, such that the soul of a highly talented witch is more valuable than that of a mediocre witch. Properly tuned, this can easily have the desired effect. For instance, say it takes ten times as much effort to produce a skilled witch, but yields a hundred times the benefit. No demon is going to want to recruit (and train) ten mediocre witches when they can get the same benefit from one skilled witch at a tenth the effort. [Answer] Learning takes time and devotion and getting more witches reduces power There's two things at work here. Demons give their power and after death witches give their power. At first a demon might not notice, but giving more and more power to more and more witches reduces their own power, weakening them. This can be exponential, making any growing in power from dying witches less substantial, unless they reduce the size of a coven again. Secondly, they receive the power of the witches. But this requires an investment in time, effort and economics. Time and effort for a lot of training, in which the demon might be necessary. But also in food and housing and the like. It is an investment that you hope to get a return on. But if you don't or barely train them, the amount of energy received at death might be many times worse than one well trained witch might offer. If this wasn't the case, demons would fast forward to the logical conclusion. Pose as a well respected powerful covenant that everybody wants to join. They join, sign, and are immediately killed. This would reduce the time bound to the demon and the witch has probably some power that can immediately be assimilated. Finally the witches might grow weary and malcontent in bad conditions. Overcrowded, not enough attention of the demon for training, not enough food, power gained is low etc. This might provoke them to try to nullify the contract. For example by cleverly using the power of the demon itself at an unguarded moment to try and kill him. [Answer] A set number of Demon Seeds (and social issues): These are solid answers, but I have a slightly different take. Since the demon places a seed in a new recruit, which expands over time, make each demon only able to generate a set number of seeds. This can be according to ability (people have 10 fingers, Demons have 20 seeds) or by agreement (treaty obligations say each coven can have no more than 30 members). It could even be by competition - Different covens COMPETE for the best new members, but are only allowed so many competitors in the competitions. Demons with big teams don't get the best players at draft time (so to speak) because they have emphasized quantity over quality. This could also be due to side-effects on society. Maybe the rulers don't like souls going to demons. Maybe there is a church out-competing demons for common souls, and only those with sufficient inherent power can break away. Maybe the witches children turn out mutated by Mana, and the human population was plummeting as a significant portion of the populus gave birth to monsters. Covens themselves may want to be exclusive (to concentrate their power) and if everyone has magic, the competition for (fill in the blank, Ley lines, spell components, special favors from demons) becomes too fierce and the strongest witches decided to eliminate the competition. Finally, these are DEMONS we're talking about. Perhaps all this warfare has given rise to a system where newly admitted members (acolytes) are not fully admitted until they have captured and sacrificed a rival coven's acolyte as an offering to their demon. New acolytes who aren't very good are going to get killed, and no one really WANTS to die at the hands of a rival gang - I mean, coven. This screens out witches who are afraid of death, or are unwilling to commit murder, and those who's magic isn't strong enough to compete with other acolytes. Covens don't want RIVAL covens to grow stronger, and selecting weaklings just feeds the membership of rival covens. Ruthless covens may even enter into arrangements together, so select acolytes are recruited purely as molech - offerings to be given to the other coven so chosen acolytes aren't at risk (this could even be punishment for poorly performing acolytes). [Answer] ## Witches are Fast Food --- [![enter image description here](https://i.stack.imgur.com/T5rti.png)](https://i.stack.imgur.com/T5rti.png) > > Human beings contain mana, which is the energy required for life. Mana > grows over the course of a person's life, being released at the moment > of death. Demons can feed on this energy to increase their power > through the creation of pacts with humans in exchange for magical > power. > > > Mana is to demons, as food is to humans. Initially, Demons competed with one another in recruiting as many humans as possible, seeking to consume as many souls as possible, as quickly as possible. However, the demons quickly realized, not only is the 'texture', or taste, of mana in the soul determined by its concentration and purity, low-quality mana also serves the same role as cholesterol in the human body. Human souls are not just composed of mana. They are also filled with emotions and feelings, an accumulation of their lives and memories. If the human suffers throughout their life, or their life end with extreme tragedy, the negative emotions will condense into grudges, becoming a 'tortured soul'. By enlisting a large quantity of humans and driving them to quick deaths to harvest their souls, a majority of these souls will also become tortured souls. Not only would the 'taste' of such souls be less savoury, there would also be deadly side-effects. Demon nobles would never be satisfied with feeding off these tortured souls, but the low-caste demons have no choice but to consume them. This is why many lower-caste demons have no sense of self, and consumed by negative human emotions, they live only as thralls for use in blood and war. ## Bottlenecks --- Another major reason, looking past the gruesome side-effects of impure souls, is that over-consumption of low quality mana contributes to bottlenecks in power increase. This is because demons have a limited mana capacity. If low-concentration mana is worth one magic unit per mana volume, and high-concentration mana is worth 10 magic units per mana volume, a demon that only feeds on high-concentration mana will be 10 times as powerful as a demon that only feeds on low-concentration mana. When the mana has saturated, a 'bottleneck' is reached, and only by obtaining purer sources of mana can the impure mana be forced out, and the bottleneck be broken through. On top of that, by putting greater pressure on their mana storage, high-quality souls allow demons to increase their capacity through the pressure over time, especially applicable to younger demons. By having both a higher capacity and higher concentration of magic, demons can become even more powerful. Powerful souls are both rarer and harder to cultivate, resulting in lower quantities, just like fine dining, but by cultivating the most powerful souls, the nobles not only avoid bottlenecks, but also train themselves to become the most powerful beings in their society. The exceedingly large power difference between demons fed by pure souls and demons fed by tainted, tortured souls, allows the nobles to keep both the lower-caste demons, and other lower-power nobles in check. As such, both noble demons and common demons alike are in need of high-purity souls, not only to avoid the nasty side-effects of tortured souls, but also to cement their power and status. [Answer] The power curve for highly skilled witches is quadratic in nature. A lowly acolyte witch is worth barely even enough to replace the power given with her soul. This will be our unit of measure, AP (acolyte power). So our lowly acolyte, works hard but doesn't manage to learn much and only becomes a tier 2 acolyte netting our demon 4 AP for his trouble. over the course of the acolytes life she may even have cost him more power from the spells she used. The demon gets a net increase of 2 or less based on how much the witch used minus his initial investment (1AP). Picking a high quality acolyte, that acolyte might become a tier 7 witch accumulating 49 AP! Assuming that the ratio to demon power spent in the lifetime to AP is about 1/2, after the initial investment of 1 AP, 48/2 = 24 AP for our demon! It also took a lot less effort than having 12 different crappy acolytes. [Answer] Instead of a cost, it can be a special reward. Some demons have figured out that if they help the seed growths on particularly gifted individuals, the quantity of mana liberated is astronomical. But it only happens with the finest, even a very strong selection of witches does not guarantee this effect. Furthermore, to help the growth of the seed the demons must limit the number of people they turn into witches. (more people less likelihood of mana big-bang) Regularly, once a year, or a decade demons must send more mana to the seeds in order to strengthen the link with the hosts. Witches created this way are more powerful but, less numerous. Demons carefully cherry-pick each of them hoping that one out of 10, 100, 1000 will create the mana equivalent of thousands of normal witches. It is a risk versus reward approach as some demons will take the risk and limit their power in the short term while hoping that in long term it will pay off. ]
[Question] [ The Gaals are a satient humanoid race, of magic origin. They were created by the last of the dragons as a legacy of his race to the world. They are humanoid, but with no hair and scales all over their body (think something like pogonas) The thing is, how to "realistically" convey sexual dimorphism in a lizard/dragon-like species? The idea of females having breast just sound really wrong, as they are nothing like mammals. Even though the Gaal were magically created by a superior being, I'd like that them would at least look and sound believable, and breasts are just the opposite. Would it make sense that the females of the species would exhibit colored or oddly shaped scales around the body? [Answer] > > Would it make sense that the females of the species would exhibit colored or oddly shaped scales around the body? > > > In most species, it is the reverse. The females and young are rather drab and the adult males are colorful. Because the females and young hide from predators while the adult males distract or fight them. If your females are colored in a way that attracts attention, then it seems likely that that species engages in the reverse. The males would care for the young while the females distract or fight them. In that case, you might want to make the females larger as well, so as to be better able to fight predators. Bright colors are often more metabolically costly to produce than drab colors. So from a mating perspective, they are a way of saying, "Hey, I'm such a good hunter that I can afford to waste calories on bright colors! I'll be a good provider for our children." In females, there is often a more direct relationship between secondary sexual characteristics and child rearing. For example, in mammals, large breasts indicate that the female can provide lots of milk for young (by converting the fat to milk). Wide hips indicate that they can give birth to large young. You might think about how these creatures feed their young and what aspects would support larger eggs. Males may have longer tails and narrower hips. Longer tails as an advertisement of their hunting abilities. Females have wider hips to lay large eggs. Females may be larger in general, particularly if speed is more important to males than size. [Answer] 1. Physical aspects due to gender roles We live in a world that is trying its level best to erase or ignore traditional gender roles. Mother Nature, however, established a number of differences. For example, as the "defender" or "the hunter," the male is generally larger, more muscular, has a thicker skull (all possible puns intended), and is more aggressive. Females are generally smaller, have mammary glands, and have wider hips for child bearing. * Define the gender roles for your species and build some physical characteristics into the race. Terrestrial lizards are egg-laying species. If your species is, too, then the rectal tract in the female will accommodate this fact. If the females defend the nests, they may have stronger spring-muscles, sharper claws, or even a stronger jaw for combat. The males, perhaps still the traditional hunter, may have a leaner form for running and a neck gullet for storing transported food (not unlike a bird). The males may have a slimmer head and longer tail for running, the females a wider head and shorter, more muscular tail for defense. 2. Behavioral aspects You haven't told us much about your race. For example, what are their mating rituals? What are their fears and delights? Humans, for example, have this quirky love for chocolate, greasy food, and The Beach Boys (well... my generation, at least). * Both genders may preen for mating, but how do they do it? Your runners (the males) may want to show their legs while the breeders (the females) may want to show their affluence (I don't want to dwell on the sterotype, but think "good housekeeper." They'd wear costly clothing, seek quality weapons, etc., to show their status). Males may prefer a vegetarian diet while the females may prefer insects (higher protein). 3. Plumage I'm fond of a line from Warren Zevon's [Werewolves of London](https://www.youtube.com/watch?v=iDpYBT0XyvA), "I saw a werewolf drinking a Piña Colada at Trader Dick's, his hair was perfect." I mentioned a bit about plumage in #2 (how they present themselves to others and why), but plumage also can be very physiological. Humans do their hair, wear rings, makeup, tatoo their bodies, and heaven only knows what else to both attract and express themselves. Again, generally speaking, men enjoy women with smooth skin and women enjoy men with rippling pectorals. Women with rippling pectorals and rough skin and men with smooth skin have for millennia been seen as "not part of the norm" and often shunned.1 Generally speaking, however, we're not like peacocks in that we don't have plumage that intrinsically changes by gender (i.e., there's not a hair color for women and another for men, like there are feathers for birds), but that doesn't mean you can't. As you said, you can use scale color (perhaps fancy for the gents, camouflage for the ladies and their nests). But you can also use scale size, dorsal spines (if your species has them), tail lengths (which I've already mentioned), length of snout/face, size of eyes... Heck, you can even do length or size of claws and digits. 4. Expression Finally, a lot of analysis has been done on what defines "perfect human beauty." Face shape, eye size and placement, hair line, etc. You can do the same here. Perhaps the men appear (to their enemies) solid, serious, unfazed by their surroundings while the women appear wise, cunning, and perhaps even devious. Extremes in these attributes may be perceived by the species as "more attractive" (which would be an excellent addition to your storyline — attractive traits that make little to no sense to your readers because, well, except for politicians and lawyers, we're not ~~snakes~~ lizards). --- 1 Yes, yes, yes... we live in a politically correct world where some will be upset that old stereotypes like this are brought up. Except that any anthropologist worth their salt will tell you that these things are real and require a sophisticated level of reasoning to socially overcome. Please keep that in mind before winding up for a scathing comment that doesn't actually have much to do with the OP's question. [Answer] Borrow from both the peacock and frilled lizards. Your females have no-nonsense frills that just get the job done. Males have extended, colorful frills. This choice gives the advantage of having ready vocabulary that is familiar to audiences when describing displays to show the difference, and of providing a plausible modification to a lizard that anyone can find pictures of on the internet. [Answer] Iguanas do sexual dimorphism right! [![iguana](https://i.stack.imgur.com/0v4K3.jpg)](https://i.stack.imgur.com/0v4K3.jpg) <https://2womenandanrv.wordpress.com/tag/key-west/> And I mean the escaped nonnative iguanas taking over the Florida Keys. The males are over the top dimorphic - wild colors like red and purple, huge spikes, giant throat flaps. As male as a lizard can be! I wonder if the founders of this population were pets that were selected for these characteristics. Or if the absence of any predation means there is no downside to over-the-top spectacularity, and the males with the best displays make all the babies. The females are plain and greenish gray. In a sentient species you could have them match the males with body ornamentation, jewels and paint. [Answer] What you want is basically sexual dimorphism, which is very common in the animal world. Some examples. * You can have a difference in size. Usually with mammals, the male is bigger than the female, but in other species it is the opposite. I know that female dinosaurs were generally bigger, etc. However, if you want to have it the other way, it's also possible, for reasons of defense. * Color can also be a varying factor. Many answers I see have the males looking flashy and the females looking drab, and I agree. However, you could go a different way and have things like the males being light green and the females dark green, or visa versa. * Physical characteristics. Other than the obvious, the males could have claws more accentuated, etc. * Social differences. Before puberty it is often difficult to distinguish male and female, but the difference is made clear through social things like hair, style of clothing, etc. A combination of all of these could definitely work. Also consider that humans are generally very good at knowing whether another person is male or female simply through subtle cues such as bone structure. Thus, if this is a book you can reference these but also use pronouns such as he/she to distinguish character's gender. [Answer] # Just give them breasts You claim that these lizards are 'nothing like mammals', which implies that: * Their face cannot produce facial expressions * Their lips are fused to their jaw * Their shoulders are narrow and attach to the base of the body * Their arms are inflexible and they cannot reach up to their backs * Their torso has a prism shape, without any defined chest or stomach * Their legs stick out around perpendicular to their body axis * Their tail is thick enough to be continuous with the body And much more --- Is this all true? If not, then your species isn't as un-mammalian as you seem to think, in which case you should probably just give them some breasts [Answer] You could expand the major differentiation beyond beyond just the physical characteristics. for example males could act more flamboyant both in seeking partners and in general interactions they could also be more competitive. Females on the other hand could act more resigned and cautious in general. You could also extrapolate on their physical appearance through clothing. Males more likely to wear colorful clothes and use flashy jewelry makeup or other such accessories. In comparison female clothes are simple and drab. ]
[Question] [ Human souls are born in the immaterium, a spiritual realm that is a reflection of the mortal world. This realm is made up of light and dark energies that symbolize concepts of "good" and "evil". For a human to be born, its soul must pass through this realm into the mortal plane, a journey wrought with perils and dangers. Nevertheless, most humans make it to term unscasthed and are born normally. A majority of souls are made up of equal amounts of light and dark energy. These energies exist in equalibrium and give humans a sense of balance. However, this is not always the case. When a soul is being formed, it can absorb an abundance of negative energy. This corruption of the soul bleeds into its biology and DNA, which causes deformities such as extra limbs, eyes, horns, etc. Mutations are passed down through their genetic line and inherited by offspring. These individuals, due to their mutations, may have certain enhancements such as strength or speed. However, they are feared and hated. More rarely, a soul can absorb large amounts of light energy and become a demigod. These individuals are similarly faster, stronger, and smarter than normal humies, but their changes are not considered mutations. Their genetic structure is perfectly enchanced with no deformities. Demigods are considered very beautiful and physically flawless. However, any offspring will not inherit their abilities and would be born normal. Why would this be the case? [Answer] Human DNA is only affected by dark energy. Light energy affects the subtle body, which is not physical. The physical and subtle bodies interact with each other, and influence each other, thus a stronger subtle body means a stronger physical body and vice-versa. By the way, the subtle body is not the same as the soul. In some religions it is called ka (not ki) or perispirit. It is an intermediary interface between the physical body and the soul. [Answer] The light energy makes them stronger, faster, smarter...and completely sterile. This could conflict somewhat with the idea of them being physically flawless, but could just as easily be part of the reason why they are viewed as demigods while the dark energy cases are viewed as mutants. Being capable of breeding with humans, the dark energy cases are clearly also humans. Just really freaky-looking humans. Whereas the light energy cases may look like humans, albeit impossibly flawless ones, but that's merely convenient form for them to take; they're clearly some other, higher, form of life. The inability to interbreed with humans only confirms this. [Answer] # Genetics vs Epigenetics ## Dark Energy is Genetic The dark energy focuses on making extra copies of the genes. More proteins for extra muscles, extra nerve connections, an extra finger, thicker ribs, a third penis. The dark energy does a blind wholesale duplication of code and traits making more of the same often to cancerous effects and in an entirely inheritable manner. ## Light Energy is Epigenetic Recently they have discovered semi-inheritable traits causes by methylation of the DNA. This prevents some proteins from expressing or causes other proteins to over express. The changes are only somewhat inheritable because the underlying code itself isn't changed, only the way that it is expresses. These changes are usually a result of the environment of the parent. A demigod whose genes were activated or silenced based on its parents' environment would pass few of those changes down because its children's epigenetics would be based on its life. The latest research has shown that extreme conditions of the grandmother can affect her grandchildren, but it is a much smaller effect. [Answer] The obvious answer (to me) is that the excess of light energy doesn't constitute a mutation; it's an infusion. Negative energy is, in this environment, a toxin. It is a form of mutagen that corrupts the DNA of the subject. What we know in genetics is that every change in an organism's DNA is a tradeoff; making a simple change that makes an organism 'better' in some respect often causes a failing somewhere else. Genetic therapy, if it ever comes out of the experimentation stage, will still be a balancing act of sorts. But, I digress. The point is that the negative energy changes the DNA so that certain mutations occur, but these often also bring a benefit along with the physical deformity. Positive energy on the other hand is exactly that; energy. This may be absorbed by the organism, but it doesn't impact the DNA directly. Instead, it makes cell division more perfect (limits aging), provides higher absorption rates of oxygen or nutrients (giving more energy, either stronger or faster), etc. This, while beneficial, is an infusion of additional energy that enhances the cells, but does not intrinsically change the nature of the cell or its DNA, hence can't be passed on. It would be a little like having a permanent medicine in your bloodstream and body through the course of your life; it provides a benefit but doesn't instigate a change. In such a case, it's the nature of the two different forms of energy that cause the difference. One has a biological impact and causes mutations, the other simply enhances the existing biology by providing additional support to an otherwise unchanged body. As such, it may even be possible for a human to be exposed to both, although it's also possible that the nature of the mutations could often impede the benefits of the good energy on grounds of changing the biological pattern to which the good energy affixes. [Answer] Consider reproduction a manifestation of the dark, a slight imperfection found in balanced persons. * Reproduction requires sexual desire which leads to selfishness, jealousy, dominerance, and obsession. * Reproduction without death leads to scarcity, hunger, and overcrowding. * Reproduction with death leads to sorrow, pain, & fear. * Children are parasites to their parents (or their parents abandon them). Both cause suffering Basically, reproduction is a dark thing, because on its own, it only leads to suffering. When balanced toward the dark, sexuality becomes an overwhelming force like a cancer not just to the host, but to all other living things. It seeks to consume all resources and destroy all competition for those resources. Dark born mutations bring power, but also shorter more violent lives. While dark individuals may rarely live very long, they tend to have large progonies that can spread like a plague over the world. The darkness of sexuality when balanced with the light creates romantic, long-lasting love that turns this dark force into a catalyst for attributes of the light: kindness, altruism, and loyalty. The light without darkness is free of all the suffering caused by reproduction. Their children do not inherit their gifts because they do not have children. They likely have no genitalia at all because their bodies are by design created to be perfect and last forever without knowing pain of death, or jealousy , or burden of children. Instead of loving only their family at the exclusion of others, they are driven to love and care for all life as though everyone is deserving of a child's love and protection. Not only are they powerful, but they live unnaturally long lives because they need not suffer or die. Light born can live for thousands, even millions of years. They can only die in the presence of a darkness that rivals their light, when such a darkness drags their body into balance making them mortal enough to kill. [Answer] Despite the fact that a person's forces are usually balanced, souls inherently like good energy, and dislike evil energy. When they are overwhelmed by too much evil energy, they try to push it away, forcing it further from the soul, into the furthest portion of the human: the body. This is why evil energy corrupts the body so readily -- most of it is already located in the body, so excess energy easily starts mutations. Similarly, since the soul clings to the good energy, it's only when they have Demigod-levels of good energy that it manages to leak into their bodies and being purifying them. Then when a human is reproducing, the soul can't help but try to force out some of the evil energy in them to the physical masses they are trying to expel from their bodies (fun fact: snot and spit are also frequently heavily weighted with "evil" energy). The parent will return to balance after expelling this energy, as the soul's inherent energy production will return them to their natural state. Since the parents' souls do not try to expel any "good" energy, even if they are a Demigod, the energy given to a child, both by the initial genetic contribution as well as fetal growth during their creation biases their initial natural state towards "evil". [Answer] well why are good "mutations" more rare in the first place if these energies are meant to be in equilibrium? If we take liberties that negative energy can also mean chaotic energy , we could argue that this energy thrives in our world. Perhaps dark energy enjoys a world of entropy like ours and would want to spread in this world. Light energy, being more centered around order, would probably reject this world and would try to return to the immaterial once the host dies. On a DNA level we could argue that light energy would be more concerned with preserving the hosts DNA rather than inducing any heritable mutations. Conversely dark energy would want to cause mutations in dna that are heritable. [Answer] Somatic vs Gametes Gametes are special cells preserved in your body from birth. These cells have their genetic repair systems tuned to over-drive and at the end of several decades their DNA is still almost identical to the DNA they started with. Somatic cells are every other type body cell, and for the most part they aren't as hot on DNA repair. Which is why most cancers occur in these cell lines. They are by no means push overs, most of the DNA sequences are still intact decades later, but there are describable differences between the DNA in your hand, and the DNA in your liver. Balanced For the most part these energies are balanced, and any spikes are well within the cells ability to repair damage. Excess Light Excessive Light energy encourages genetic abnormalities, and particular protein complexes that are generally hyper-beneficial. The overall health, and function of the particular creature is increased. The powers begin to manifest shortly after birth, and continue to accrue as they age, causing older individuals to be quite god-like in comparison to their younger selves, while also allowing their own parents to raise them before they become too god-like. This hyper-beneficiality however is not without its downsides. A fetus coming into existence with X+ years of demi-god like evolution is simply too risky for a mother to carry to term. If the father was the god-like individual the likely-hood is that the baby would drain the mother of all physical resources essentially killing her. Conversely a god-like mother carrying a god-like child would be able to carry the fetus into a much later term but would likely suffer serious injury when the fetus begins to kick. After all the mother is not protected from a herculean punch from within her. At best the baby would be born premature, the only thing helping it would be the god-like powers. Unfortunately though the baby would likely die due to lack of care. Anyone who attempted to render that care would likely be harmed, the bottles used to feed it snapped like twigs. This is a problem for evolution, because all the women, or all the men wish to mate with a single demi-god (because they are by far the best), and demi-god like fetuses kill the mothers. This would be disastrous for a species. It would be better if those abilities had not been passed on. Hence biology suppresses these changes from occurring in the gamete lineage. The species that did not adapt this way have already died out. Excess Dark Excess dark energy tends to afflict the gene responsible for body-layout and alters the production of certain protein complexes. For any specific individual these induced changes are relatively stable, and manifest at the developmentally appropriate age without further negative effect genetically. This has the effect of produce poisonous bile (even to its ownself), extra legs, no legs, and other abnormalities. Generally speaking these mutations are horrible for the individual they are inflicted on. However from a species perspective these are a great chance, every now and then the mutation is successful, and repeatable. This encourages speciation: Snakes from lizards, whales from land predators, pegasi from horses. Due to the advantage in the long run, most species do not overly suppress the genetic deformations caused by dark energy in the gamete lineage. Some may in fact encourage it, hoping to increase the rate of speciation. Which is better Obviously light is great for individuals, but horrible for the species. This tug of war ensures that individuals do not confer their god-like propensities. Dark energy is better for the species giving them more baskets to store their proverbial eggs in. This allows entire families of similar species to handle changing environments, and extinction events - some of them are likely better suited to living and survive. The unfortunate downside is that many afflicted individuals experience short, brutish lives until normal evolution smooths out the issues. Imagine a horse with skinny protrusions from its back, that horse is going to have a bad life, but perhaps its descendants learn to use those protrusions to fly, now they are a gift allowing escape from many predators. [Answer] ## Simple recessive traits Assuming demigods can interbreed with humans, the demigod type alterations are recessive, and simply do not exist in the normal human population. The human's dominant genes will always override the demigod's recessive. If human offspring of demigod's are common enough, then you might have a respectable percentage of humans carrying the recessive traits, and so the following detail comes into play - the traits expressed by the genes are an all or nothing proposition (or maybe you can get some minor effects that might indicate heritage, but nothing near the flawless appearance or power of the full demigod). One of two things could happen, depending on how you want such offspring to be in your world: 1. Incomplete demigod gene sequence just fails to produce the godlike abilities, but the offspring is otherwise normal or even slightly enhanced (still exceptionally beautiful, but not inhumanly so; stronger than usual, but just slightly; etc.) 2. The incomplete sequence causes congenital defects - perhaps not on the order of the corrupted souls, but noticeable and severe and not supernatural - likely resulting in a higher than normal number of still births or miscarriages. ## Why doesn't this affect the dark souls? The dark soul mutations are simply less powerful, and less genetically complex. They are dominant, they might have an elevated nutritional requirement, but nothing unmanageable without the help of a "special" soul, etc. Which leads me to a third option... ## Because the souls will it thus In fact, this may be by "intent" - evil wishes to spread, good tempers its influence on the material world since such power could corrupt an insufficiently good soul. As such, the evil souls warp the body in a way that is easy to pass on, with the expectation that power corrupts, and a normal soul born into such a body will then be corrupted and spread more evil and chaos. Good souls, on the other hand, realize that a normal sould given such power is much more likely to abuse it than not, and so not only exercise safe sex (perhaps), but also go the extra mile to ensure that their offspring would be normal or unviable by manipulating the ova or sperm they produce. [Answer] I can think of a few reasons why this would be the case. So I am going to put it simply and do my best to be clear as I list the probable causes: 1. The absorption of dark energy is much easier than light energy. For every 1 light energy "unit" you'll have 100 dark energy "units". This could be because there are more binding zones for dark energy than there are for light energy. Using enzymes as an example dark energy is an extremely common type widely used and produced; with the supporting energy receptors being likewise common. Thus it is also easier for things to go wrong and for dark energy to be absorbed in excess due to environmental and biological factors. On the opposing spectrum we have light energy,a rare but valuable form of energy that can create great benefits when absorbed. But is rarely absorbed in high quantities due to the infrequency in which it is needed and produced. Ideally the soul has equality and balance. But if dark energy is more common,being a "physical" energy (one affected the most by biological and environmental factors) it will always have the advantage in conditions for propagation and absorption. With those born with higher levels of dark energy also having more advanced and potentially useful adaptations. Which would favour survival of the fittest,as variety is king until proven otherwise. While light energy is the base "mental" energy of the soul. It is the energy of the spirit which has the primary purpose of keeping balance with the physical energy of dark. However unlike dark,there is a much lower rate of expression in light energy as it is less likely to bind to energy receptors on the body. The reason being simply that there is far more potential dark energy than light energy. Leading to the dark energy crowding out the light energy in most cases or being at best in equilibrium. The rare cases when light energy is dominating could be because the host body has energy receptors "shaped" to take only light energy. Which ironically could result due to the individuals parentage having high amounts of dark energy;triggering mutation in the unborn to attempt to reach equilibrium upon sensing the massive presence of dark energy (that of their parents while in the womb) but end up absorbing far more light energy due to it being produced in such vast quantities to try and counter the dark energy sensed by the soul all around it. This in turn means that demigods would most often be born to mutant parents as a sort of species variant resembling a perfected version of their ancestral human form. Which in turn could lead to primitive mutants regarding these beautiful,strong and intelligent individuals as demigods. While in more civilized realms who discover this secret,having a mutant surrogate carrier for a child to try and force a demigod birth could become a risk rich individuals are willing to take. 2. Dark energy could be produced naturally but also result from converted light energy. Just as proteins can be deformed and denatured creating bad DNA,dark energy could bind to light energy itself or to light energy receptors. Causing it to be unable to bond with the host body,either through blockers or denaturation of the light energy. Thus resulting in an artificial surplus of dark energy. While the light energy is rendered useless due to it becoming twisted. With the unaltered bits maintaining equilibrium. This could also be a result of biological factors favouring dark energy for the purpose of evolutionary diversity. So it is the body itself which tries to make conditions ideal for dark energy while maintaining equilibrium. Thus if the DNA (?) was damaged which controlled and regulated this function (the body was sick,genetic disease,malnourished in the womb,curses or hexes upon the unborn,or being predisposed towards mutation) you'd end up with a mutant being born. While in ideal conditions (think the miracle birth) the body would be in a low dark energy environment (artificial birth?) allowing it to take in strictly light energy. 3. Demigods could be artificial. They in effect would be designer babies created by siphoning the dark energy out of the unborn child into another receptacle. (Such as another child from a less well-off family,an animal or even a premade "dump" clone) Thus they are rare due to the unethical means and expense by which they are born most commonly. With a very small amount being born due to mutation or birth in isolation. Just my opinions on the matter,I hope it makes sense and aids you in finding your answer. [Answer] There is no light. There is only a lack of dark. Consider real dark. It is not a thing. It is a lack of light. In your world it is reversed. Humans at equilibrium (and everything else) have a certain amount of dark energy acquired from their environment during gestation. It is normal. Demigods thwart that normality thru luck or skills or effort, jettisoning the dark energy that is their birthright and so becoming relatively light. Their progeny acquire dark energy at birth, like everyone and everything else. The demigodly individuals have a deficit, not an excess. You cannot give your progeny something you don't have. As noted some humans, either by their misfortune or efforts, acquire more than the normal amount of dark energy. They do have something to give. This excess bleeds off and contaminates their progeny and also other things which have prolonged contact with these individuals. Also, once an individual is out of equilibrium it will continue in that direction. A concentration of dark energy in excess of that naturally around it will tend to attract more dark energy, like a gravitational mass. Those with an excess of dark energy will tend to get more and more as time passes. The reverse happens to the demigods because their lack of dark energy means that they have less "gravity" than other things and so remaining dark energy will tend to slip away from them causing their power to increase. --- This leads to potentially interesting things for the story. An individual powered by dark energy and interested in getting more will find the most in other individuals similarly powered by dark energy. A dark individual with more "gravity" can pull energy away from another individual. This could have the effect of curing that individual of afflictions caused by dark energy. The proximity of a person or object with a lot of dark energy could pull energy away even from normal persons, shifting them towards demigods. [Answer] There were light particles emitting light energy, without any dark particle around. Then somehow, arrived a bunch of dark particles emitting dark energy.(Or both arrived at the same time in a big boom, or there was a neutral "0" particle that somehow divided itself into "+1" and "-1" particles). Light and dark particles attract each other, but dark energy repel light particles, and light energy repel dark particles. So they attract each other but once they get too close, they start repelling each other. They both have different behaviours when it comes to interact with their own kind. Dark particles will try to occupate as much space as possible, while light particles will try to concentrate into one tight big light ball. The total available space where both light and dark live in would be something based off the amount of energy turned into repulsion. To be able to take as much space as possible, dark energy would try to put itself in between light particles. If there are as much light as dark particles, it leads to nice geometrical forms, but not as perfect as a nice spherical ball of light. If there is more dark particles than light particles, there will be some weird geometry surrounded by dark particles moving all around the thing or causing perpetual movements and shape changes, causing difformities. As most of the energy gets turned into repelsion when dark and light particles get close to each other, things that have more of one kind than the other will emit more energy, thus, being stronger. As light prefer being in only one ball, it will not transmit its particles to its offspring. Darkness takes as much space as it can, the dark particles moving around the shape will try to enter inside other shapes that have less darkness particles than the one it actually rotate around, they somehow have shape memory, thus, transmit difformities to their offpsring. (Or, differents human DNA have different ways of dealing with excess of dark energy . Instead of transmitting DNA difformities, you transmit both the excess of dark energy and your DNA, and your DNA dictates the shape your soul will take if there is dark energy excess) In this scenario, DNA could just be the physical "mortal world" representation of the shape of the soul, or could dictate the shape your soul can take, your choice. And as it is actually, it's neutral, light doesn't mean good and dark doesn't mean bad as is. Human interpretation tho, will quickly turn this into: "Light is better because it tries to bring stuff together" and "Dark is bad because it tries to separate stuff to conquer more space". [Answer] Light energy simplifies genetics; Dark energy increases the complexity of genetics. The genetics of demigods have almost none of the randomness and variation of a normal human. The most well-established, dominant evolutionary traits of humans are expressed in their most efficient and stable forms. Physical features are highly symmetrical and without outlying or exaggerated features, traits that are commonly considered attractive. Demigods may even have a distinctive look common to them, an almost unnatural geometry and smoothness in their faces. They could also have an androgynous appearance, with many of the differences between male and female bodies being simplified and brought closer together. The Light energy is essentially "cleansing" the genetic material of unneeded "waste"; the genetic potential that would have been diffused across all those other random characteristics is now focused on expressing the remaining traits to maximum potential. A side effect of all this is that breeding becomes impossible; essential genetic material for reproduction has been discarded in the process. Dark energy does the opposite, it accelerates the complexity and randomness of genetic material. Recessive genes long dormant in human DNA can have new connections made to them in the explosion of genetic complexity, reactivating characteristics from far back in human evolutionary history (tails, horns, etc). Size, shape, colour and all aspects of physical characteristics can vary wildly from human norms with exaggerated increase or decrease in effectiveness and potentially completely new structures and uses birthed from the chaotic hyper-evolution of the genes. ]
[Question] [ Is it possible (either through genetic engineering or evolution) for a biological creature to be able to detect and absorb electricity from power sources like batteries or other animals? I know that a shark can detect electrical fields (via its Lorenzini ampulae) in water, but can a biological creature detect it in the air? If this can be done, how would it work? Absorption through touch? And can it discharge the stored electricity like an electric eel as a means of defense/hunting? What would happen to its victims if their electricity is drained? [Answer] # Yes. You want a hornet-like platypus in the rainforest. Hear me out. Water conducts electricity substantially better than air, salt water in particular. Therefore, [electroreception](https://en.wikipedia.org/wiki/Electroreception) - the ability to detect electric currents - is far more common in marine life than terrestrial creatures. Now, it's not nonexistent in land animals; electroreception occurs in [a select group of them, the monotremes](https://en.wikipedia.org/wiki/Electroreception#Monotremes). The platypus and echidna are notable examples. In particular, [long-beaked echidnas](https://en.wikipedia.org/wiki/Long-beaked_echidna) live in damp areas of forests. The high humidity in the echidna's habitat makes it possible for it to detect sources of electricity, even weak ones. The [platypus has an even more refined sense of electroreception](https://en.wikipedia.org/wiki/Platypus#Electrolocation), also enhanced in regions of high humidity. Your animal will, therefore, likely live in a wet, moist, humid area, probably the tropics. A rainforest is a possibility - a habitat favorable to a platypus. Stay away from deserts and dry, barren areas. Furthermore, areas near lakes and streams might be preferable; the platypus can swim, and electroreception is even more valuable in the water than on land. That might also be a good evolutionary reason why your creature developed electroreception but lives on land: its recent ancestors were mainly aquatic. We still have to deal with the question of how your animal absorbs, stores, and uses electricity. Absorption would likely happen via modified [electrocytes](https://en.wikipedia.org/wiki/Electric_organ_(biology)#Electrocytes). These are cells - found in certain electroreceptive animals - that use [ATP](https://en.wikipedia.org/wiki/Adenosine_triphosphate) and ion transport to generate electricity. I'd image that running the process in reverse - kind of like turning a motor into a generator - could then use the same pathways to generate ATP, which the animal would store for later. When it comes to using the electricity, you might want to look at processes in the [Oriental hornet](https://en.wikipedia.org/wiki/Oriental_hornet#Electric_Potential), which uses sunlight to create an electric potential in its wings. [The exact mechanism through which the hornet uses this is unknown](https://blog.nationalgeographic.org/2014/06/26/the-shocking-truth-about-electric-animals/), but it could be used for energizing muscles or for [enzyme creation](https://www.sciencedirect.com/science/article/pii/S1095643309000300); the hornets are more active when their wings are exposed to more light. I suppose your creature could use the electricity directly for similar processes, or simply store it via ATP and use that for normal cell functions. Of course, having electrocytes, or cells just like them, means that you should be able to generate electricity and use it to attack other animals. Many species do this, including the infamous [electric eel](https://en.wikipedia.org/wiki/Electric_eel). Now, for your terrestrial animal, attacking with electricity would likely only be a successful method in close quarters combat - remember that air isn't that conductive. Nonetheless, luring prey in until it's within striking distance and then discharging could still be an effective strategy. [Answer] ### Units Before we begin, let's get our units straight. * [Energy](https://en.wikipedia.org/wiki/Energy) - an absolute amount of energy measured in [Joules](https://en.wikipedia.org/wiki/Joule), Watthours, and calories. * [Power](https://en.wikipedia.org/wiki/Power_(physics)) - energy applied over time, measured in [Watts](https://en.wikipedia.org/wiki/Watt) or Joules per second. 1 Watthour is 1 Watt of power delivered for 1 hour. A Watt is 1 Joule/second. 1 hour is 3600 seconds. So 1 Watthour is 3600 Joules. This gets important because while some biological organisms can deliver a lot of power, like an electric eel shock, they do it for a very, very, very short period of time resulting in very little energy transfer. --- ### "Draining" an organism's electricity No, you can't make an organism that drains the electrical energy of another organism. Organisms aren't batteries that can be drained and nerves aren't wires. Instead, each neuron acts like a member of a [bucket brigade](https://wikipedia.org/wiki/Bucket_brigade): An [electrical potential](https://wikipedia.org/wiki/Action_potential) travels along one of its [axons](https://wikipedia.org/wiki/Axon), which is somewhat like a tentacle on an octopus, all the way to the [tip](https://wikipedia.org/wiki/Axon_terminal) of the axon through the movement of sodium and potassium [cations](https://wikipedia.org/wiki/Cation). These cations move in and out of small “[gates](https://wikipedia.org/wiki/Voltage-gated_ion_channel)” in the membrane surrounding the partitioned compartments which are strung along inside the axon: The ions do not move down the line, but they cause the gates in the adjacent compartment to open and close. And, so on. Nowhere there does electricity flow like it does through metallic wires. At the tip of each axon is a [synaptic gap](https://wikipedia.org/wiki/Synaptic_cleft) between it and the tip of another neuron's axon. The signal is transmitted across the [synapse](https://wikipedia.org/wiki/Chemical_synapse) by the release of special uncharged — electrically neutral — chemicals called [neurotransmitters](https://wikipedia.org/wiki/Neurotransmitter). All grossly simplified, of course. I said organisms aren't batteries... but they are. Nerve cells are "charged" by chemical energy from things like [ATP](https://en.wikipedia.org/wiki/Adenosine_triphosphate). They use [this chemical energy to transport ions against the magnetic gradient](https://en.wikipedia.org/wiki/Ion_transporter) creating potential energy in the form of a charge between the two cells. Nerves are, in effect, little capacitors. But you can see there's normally nothing to draw energy from as nerve cells only have a charge relative to each other, and it's all insulated from the outside world anyway. Were you to somehow magically overcome all that insulation and absorb the potential energy in the nervous system, the nerve cells would use the chemical energy from ATP to charge up again. I don't know what effect this would have on the organism, but nerve cells normally charge and discharge thousands of times a second. Basically "absorbing" the organism's electricity means eating the organism. Which is what many organisms already do. --- ### Electric Eels and Static Shock Though you can [build up a charge in an organism by insulating it from the outside world](https://en.wikipedia.org/wiki/Body_capacitance), what we call "static electricity", and can harvest that little bit of electricity, it's inconsequential in most organisms. Because it can damage sensitive electronics, [Fundamentals of Electrostatic Discharge Part Five--Device Sensitivity and Testing](https://www.esda.org/assets/Uploads/documents/FundamentalsPart5.pdf) provides a delightful simplification of the human body. > > The HBM testing model represents the discharge from the fingertip of > a standing individual delivered to the device. *It is modeled by a 100 pF capacitor discharged through a switching component and a 1.5kΩ series resistor into the component.* This model, which dates from the nineteenth century, was developed for investigating explosions of gas mixtures in mines. > > > [![Model circuit of a typical human body](https://i.stack.imgur.com/bLnFr.png)](https://i.stack.imgur.com/bLnFr.png) The human being, according to an Electrostatic Discharge tester. Can we get any useful power out of this? We can calculate the energy of such a jolt. $\text{Energy} = \frac{\text{Capacitance} \times \text{Voltage}^2}{2}$ Numbers vary for the human body, but the highest I've seen is $C = 400 pF$ and $V = 50 \text{kV}$. Make the voltage much higher and it will ionize the surrounding air and discharge. [Plugging those in we get 500 mJ](https://www.wolframalpha.com/input/?i=500+millijoules&lk=1&rawformassumption=%22ClashPrefs%22+-%3E+%22ClashPrefs%22) which is roughly the energy to lift an apple 50 cm, or more poetically, the acoustic energy of 50 whispers. Electric eels produce their shock in a similar way, but they have [modified muscle and nerve tissue](https://en.wikipedia.org/wiki/Electric_organ_(biology)) to create a [voltaic pile](https://en.wikipedia.org/wiki/Voltaic_pile), a simple battery. They're charged in parallel, then switched to series to release a jolt. There's thousands each producing 0.15V which leads to quite a high voltage. Discharged at 1 [amp](https://en.wikipedia.org/wiki/Ampere), it can produce 860 watts of power which can literally quite a shock. But [it only happens for 2 ms so it only delivers 1 or 2 J](https://www.wolframalpha.com/input/?i=860+V+at+1+ampere+for+2ms). To put this in perspective, [1 gram of meat contains 9000 J of energy](https://www.wolframalpha.com/input/?i=calories+in+1+g+of+meat). If you're looking to get energy from an electric eel, eat it. --- # Absorbing from an outlet In theory, you could run the process backwards. Instead of using ATP to create a charge you could use a charge to create ATP. The problem is getting this energy to the cells without frying the organism. You can't just absorb it through the skin, skin and fat are very good insulators so you'd fry them overcoming their resistance. You'd need specialized organs to act as "wires". Handwaving exactly how this would work, how much electricity do you need? To get a rough estimate, a typical human weighing about 75 kg needs about 2000 kcalories, or 8 MJ, per day. That's about 100kJ/kg. Let's say you "charge" for 2 hours a day, that's $50 \frac{kJ}{kg \times hour}$ or [about 14 Watts/kg](https://www.wolframalpha.com/input/?i=100kJ+for+2+hours). So our typical 75 kg human charging 2 hours a day needs 1050 Watts. This is roughly the power draw of a microwave oven or kettle or toaster, which isn't unreasonable. The problem is [1050 Watts at 110 Volts is 9.5 Amps](https://www.wolframalpha.com/input/?i=1050+watts+at+110+V) ($Power = Voltage \times Current$) which will definitely kill you. But maybe your organism can handle this somehow. Point is, it's a lot of energy coming in fast. It's enough to toast bread and boil water. Your organism would need a way to dissipate and distribute it fast. --- ### Magnetic field detection Numerous creatures can detect magnetic fields, and electricity generally creates a magnetic field. [The Magnetic Sense of Animals](https://www-s.ks.uiuc.edu/Research/magsense/ms.html) (really organisms) breaks down the detection mechanisms for us. * Mechanical - tiny magnetic particles that act like little compasses and orient themselves with a magnetic field * Induction - moving through a magnetic field induces a current in an organ in the organism * Chemical - magnetic fields can change spin states which can be noticed by an organism Normally there are two reasons to detect magnetic fields. * Navigation and orientation along the Earth's geomagnetic field * Prey/predator detection - since organisms put out a weak magnetic field If you wanted to try to get energy from this, the best option would probably be induction. But as we showed above, there just isn't much energy to be had from other animals. Meat is very efficient at energy storage. --- ### Conclusion Chemicals are much better than electric charge at storing energy. That's why we evolved to use it to store energy, technologically and biologically. Organisms don't store electricity, except in special cases where there's some advantage to be had, and then very small amounts, and very inefficiently. We store chemical energy and convert that to electricity on demand. That's also why we evolved to eat each other. There isn't much electrical energy in an organism at any given time, even an electric eel's jolt is only 1 or 2 J. An organism's energy is locked up in chemicals. It's much easier to eat your prey's chemicals than to get your prey to convert their chemicals to electricity for you, absorb that, and turn it back into chemicals for efficient storage. Organisms which do feed directly off energy, [photosynthesis](https://en.wikipedia.org/wiki/Photosynthesis), are [quite inefficient](https://en.wikipedia.org/wiki/Photosynthetic_efficiency) and don't have the energy to spare for movement or complex actions. [Answer] Eating electricity is possible. In theory we could even do it. ATP is the energy currency of a cell. If a cell can make ATP, it will make more when exposed to an extrinsic electric current (of the correct magnitude). <https://frequencyspecific.com/wp-content/uploads/2016/04/Cheng-1982.pdf> [![Table showing the effect of extrinsic current on ATP generation](https://i.stack.imgur.com/rkYY4.jpg)](https://i.stack.imgur.com/rkYY4.jpg) This experiment was in rat cells. At maximum they produced 5 times more ATP than at baseline. Stronger currents damaged the cells, probably thru ohmic heating. The report notes that the same thing was found to be true for chloroplasts. Exogenous currents stimulate synthesis, probably by increasing available ATP, and are used clinically to promote bone healing. <https://www.ncbi.nlm.nih.gov/pubmed/20182239> An interesting experiment: measure growth of a test organism (yeast?) in a calorically restricted environment, one with a current running thru it and one without. Can the electrical current "calories" boost development of biomass over what the control group achieves with regular calories? What a cool experiment that would be, and easy! Science fair, anyone? Anyway - your creatures: if they have access to a reliable source of current they might tap into that to augment ATP production - or conceivably be their entire source of energy intake. I proposed organisms that would use a piezoelectric current for energy generation in this questions:[Could plants generate energy using wind power?](https://worldbuilding.stackexchange.com/questions/112711/could-plants-generate-energy-using-wind-power/112718#112718) A current implies time. The electrons must flow. So to get a current running thru you, you must glom on to the source or generate the current constantly (like the piezo trees). You might have something which can accumulate charge like an electrical eel because that would let it keep the current thru the ATP generators at a consistent healthy level and save some energy for later - like we accumulate calories we eat for later use. As regards draining victims, most animals are not producing an electrical current through them. If there is a charge difference between me and, say, my brothers ear, the charge differential equilibrates suddenly with a static spark. Current implies a slow equilibration of charge difference which requires either some mechanism to keep it slow or a constant generation of charge on one side. Your charge eaters would probably not be going after biological electricity. ]
[Question] [ My story is set within one solar system, which can be assumed to have a similar composition to that of our own: one Class G star, a handful of rocky inner planets and a handful of gas giants on the periphery. The backstory is that this was a colony from Earth that arrived on a generation ship many hundreds of years ago and has since lost contact with Earth; though this isn't pertinent to the question. The setting calls for relatively hard-science, so normal Sci Fi tech like inertial dampeners, FTL, and artificial gravity are off the table. In a [book series with a similar setting](http://expanse.wikia.com/wiki/Category:The_Expanse), interplanetary travel was achieved with "fusion drives" which allows for subluminar travel between planets in a few weeks or months. However, while fusion reactors are feasible within my story, a fusion drive still seems like a hand-wavey solution to the problem. What I would like to use instead is a series of mega-structures in orbit around the various planetoids that act as large [gauss cannons](https://en.wikipedia.org/wiki/Coilgun) to "throw" vessels from planet to planet. Essentially, large interplanetary vessels would be designed to be loaded into the cannons and then fired as a projectile. The cannons themselves would of course need to be massive, on the order of 25km+ in length with massive power requirements to run the magnetic coils. When the ship is arriving on the other end, a similar mechanism captures it and uses the same rail gun assembly to slow it down. Some issues I've identified with the tech and how they could be addressed: * Failure condition: in the event that the receiving end of a transit could not capture the craft (for whatever reason) each vessel has enough fuel on board to perform one orbital injection burn as an emergency measure to prevent catastrophic failure. * Human survival: the accelerations associated with launch and capture would be immense. I haven't done any math, but I'd guestimate on the order of 30+ Gs for a minute or so. Passengers would spend launch and capture unconscious in specialized "crash-couches" that would prevent death during acceleration. What I'm looking for is an assessment of this method of transit for interplanetary travel compared to other semi-realistic methods; like fusion drives, ion propulsion, or giant chemical rockets. To be clear, my narrative requires that this is the method of interplanetary travel I use, so I'm not looking for alternatives. What I want to know is how realistic this method is and/or if there are any tweaks I can make to improve it. Some things to consider: * Economic viability of maintaining the mega cannons vs. other methods of transport * Safety of both vessels and launch/capture destinations using this method * Practicality when considering method requires infrastructure at both ends of the transit path * Whether orbital paths can be calculated with sufficient accuracy [Answer] # Yes but no Theoretically yes, the [space gun](https://en.wikipedia.org/wiki/Space_gun) concept has been rattling around since the days of [Jules Verne](https://en.wikipedia.org/wiki/From_the_Earth_to_the_Moon), it's certainly not new. The first problem, as you've already mentioned, is surviving the launch. Given that you're using it as a catching mechanism as well, you've added surviving arrival to your problems. The acceleration required to achieve a viable interplanetary speed out of such a ~~weapon~~ launch mechanism would destroy anything more delicate than a house brick, and even that is unlikely to come out entirely intact. > > # Acceleration > > > <https://en.wikipedia.org/wiki/Space_gun> > > > A space gun with a "gun barrel" of length (l), and the needed velocity (v), the acceleration (a) is provided by the following formula: > > > a = v2/2l > > > For instance, with a space gun with a vertical "gun barrel" through both the Earth's crust and the troposphere, totalling ~60 km of length (l), and a velocity (v) enough to escape the Earth's gravity (escape velocity, which is 11.2 km/s on Earth), the acceleration (a) would theoretically be more than 1000 m/s2, which is more than 100 g-forces, which is about 3 times the human tolerance to g-forces of maximum 20 to 35 g during the ~10 seconds such a firing would take. > > > To bring that down to a "reasonable" or at least survivable, 30g, means you need a "gun barrel" of at least 200km in length, megastructure is definitely the right word here. Economically, building this could be ruinous, as could running it. I'll leave the energy calculations to the reader as target speed has not been stated but you can probably assume efficiencies of 10-25%. There's the typical minimal safety involved in any crude space travel, you hope to miss, because if you hit your monument is going to be a large crater. However reaching your target to metre accuracy is just a matter of maths and if you can make the launcher work, it's reasonable to target that well. However, and it's a big however, you're effectively trying to thread a needle by tying the thread to a bullet and firing at it from across the room. It might work, but you're more likely to leave a big dent in the plasterwork unless you're really good. # Actually making it make sense The basic concept has some advantages, the "ships" can be basic pods, much cheaper and simpler than a self contained interplanetary vessel. More of the mass and volume are dedicated to cargo. If you can make the launch system efficient enough you could possibly work out an economic model under which it makes travel commercially viable. (You can't in practice as end to end has to be effectively free, but never mind that.) Space traffic control is a nightmare, this is a model that requires a much higher traffic flow rate than any self contained vessel. Remember that for a single ship travelling under its own power, the cost is the same, whether for the first ship or the hundredth. For this system, the massive up front cost means that the effective overall cost comes down for each subsequent launch. It's a 200km long structure, it cost a vast amount of money, you have to get a traffic rate that makes it cheaper than single launches. [Answer] Disclaimer: This is all rampant speculation by an enthusiastic amateur. The problem as I see it is the acceleration is literally killer. So the solution is to ramp up to speed slower with a gauss cannon taking the form of a mag-lev track running in a wide circle with a switch-track to curve off gently to the final trajectory. (it'd have to be a gentle curve rather than sudden straight simply because the change of trajectory would itself affect acceleration) Your Catcher would have the same configuration, you'd simply enter through the switch-track and decelerate in the ring until you reach a velocity gentle enough that you can be safely released from the system. This has some advantages, if you accelerate at 1g you would get the benefit of centrifugal forces on your passengers until you join the switch-track, making the probable weeks of acceleration/deceleration much more tolerable to the human frame. Some problems would be that your ship would be the only ship that could be in the loop at any time, any later ships would rapidly catch up and collide with the first one within the first loop around. So your massive infrastructure would have potentially a very small payload and quite low turnaround. The possibility of using this for cargo is much more likely, you could apply much higher changes of velocity in the system without worrying about pasting fragile fleshy people. [Answer] There's one critical consideration that none of the answers so far seem to cover (unless I missed it). Newton's 3rd Law of Motion Commonly summarized as "for every action there is an equal and opposite reaction." This means you're accelerating your space station in the opposite direction with every launch. This in turn means that after every launch, your station has to return to station by traditional means. You can't escape this reality. Either you have to fire and equal mass object at the same velocity in the opposite direction(really dangerous) or you have to burn engines to counter the thrust. [Answer] I don’t think a gauss cannon is a good solution in part because of the tremendous acceleration required and in part due to the massive infrastructure needed. However it is almost certainly possible. I would suggest a large number of wide torus shaped electromagnetic stations aligned so as to enable a craft to be accelerated through each one. When the cannon was needed these electromagnetic stations would be positioned along the proposed trajectory and the interplanetary craft would be accelerated through each one in turn. After the craft had left the “recoil” would have to be damped by using the electromagnetic stations to repel one another as the end of the series would probably need to be free floating stations due to the great lengths involved. There are too many variables to provide any exact numbers but I imagine the cannon would need to be of the order of tens if not hundreds of kilometres in length if you didn’t want to crush the crew. A nasty but survivable 10g applied for 40 seconds would give a space craft delta v of 4 km/s, enough to get from Low Earth Orbit to Mars. But it would need 80km of launch “tube”. Assuming your brutally punishing 30g the same velocity could be achieved in under 14 seconds with a tube length of around 26km, however I think you would need a lot of back story hand waving to explain why the crew generally survive rather than generally die. One big issue would be alignment, especially if the far end accelerating stations were free floating. That said with high tech I would have thought this should not be insurmountable. There would also be the matter of recoil the free floating stations might crash into the other parts of the cannon if the breaking failed. Perhaps some emergency thrusters could push them out of alignment if this happened to avoid collision. The economics of this would depend on too many variables. All I would say is that a massive amount of electrical power would be needed as would massive orbital stations so both power and space construction need to be relatively cheap. The safety is in part dependant on the forces used even 10g is not really “safe” and 30g is probably deadly in many cases. The infrastructure would be huge and not very practical. A new cannon would be required for each destination whereas conventionally propelled craft could go anywhere. I doubt that there would be any serious problems with calculating the correct trajectory and orientation of the cannon, although mid-course correction would probably still be required by the use of thrusters of some sort (ion drive would be my suggestion here). I suggest that the craft carry ion engines as backup. They will already have powerful electrical generation capability for use in conjunction with the gauss cannon so it would make sense to use this for the backup plan. The propellant required could also be much lighter as the exhaust velocity of an ion engine is very high. In summary its an interesting idea but not really that practical. You might want to consider other variants depending on how wedded you are to the static cannon idea. Perhaps a hybrid cannon/ion drive, a multi stage cannon or a series of cannon like accelerators in continuous orbit used by craft in both directions for acceleration and deceleration? [Answer] Following up my original answer, I went looking for statistics on 1G accelerations. I turned up this gem <https://space.stackexchange.com/questions/840/how-fast-will-1g-get-you-there> By my estimation, at a steady 1g, passengers would spend 11 hours in the loop at each end, and about two days of flight-time coasting between earth and mars under optimal conditions at 401,235 m/s (estimated for a 45 hour flight based on the optimal 1G powered flight profile with a turnover in the middle) 3 days to mars sounds cool, but it's highly contingent on the loop's ability to divert that kind of velocity into a curve. the more powerful the magnetic containment the smaller the loop can be. Scale affects everything, your projectile is moving 4000 times faster than the fastest bullet, so that forces your loop to be very big indeed, very likely the loop would need to be a ring all the way around the moon or earth itself, under those circumstances your best option is probably to build multiple orbiting facilities with their own sections of gauss coils. far easier than building a contiguous structure and it'd be inherently much easier to upgrade and replace parts. you could also use the facility from day 1 of construction at reduced capability and improve it as funds and resources permitted. [Answer] Highly unrealistic. Economic viability: Maintaining rail gun systems is extremely costly. As it stands with Rail guns right now. The Barrel has to be exchanged every couple of shots because it melts due to the heat generated by accelerating the payload. Safety: Extremely unsafe. The passengers probably wouldn't survive the extreme acceleration of the cannon. Having fuel on the vessel to correct the flight path would certainly result in an immediate explosion inside the cannon. Practicability: There's no way to effectively catch the vessel. Also, as @Rekesoft already said in the comment, there are way better launch systems if you already start from orbit. Calculation of orbital paths: Should not be a problem. [Answer] 1. Loops a. Gradual Acceleration Multiple answers to this question have mentioned the idea of using a loop rather than a straight barrel to ramp up speed over time rather than turning the occupants of your craft into a G force induced paste. I would wholeheartedly agree with their idea as it allows us to bypass the need for special safety measures on the occupants, and adds an interesting quirk to your space travel in that travelers would be forced to wait in these acceleration loops for a period before leaving and after arriving at planets. b. Modularity The system can be built incrementally making travel faster and more efficient as each new module is installed. This will assist in offsetting the structures gargantuan cost. 2. Psychology This is going to sound weird, but I think one of the largest barriers to entry here is psychological. If I put you in a car and give you the controls, you feel like you are in control. However, if I place many individuals into a plane where they have no control, they become anxious even simply unable to function. This problem is magnified greatly if I am going to be sending people millions of miles at speeds approaching the speed of light with no way of helping themselves in the event that something goes wrong with the catching system, or a miscalculation occurred with their trajectory. This brings me to my next point. 3. Targeting Space craft missing their marks when simply trying to hit a planet is a concern, let alone hitting a small, say few hundred meter wide, target. For instance, Curiosity's landing zone was a 12 mile by 4 mile ellipse. Did it land within that ellipse, yes, but that kind of uncertainty simply will not do in a system like this. Accuracy is getting better, but errors can always occur. Source: <https://www.nasa.gov/mission_pages/msl/multimedia/pia16039.html> Granted, the spacecraft in this system should never have to deal with any sort of drag or air resistance pushing them off course, but as vacuous as space is, you cannot assume your path will always be clear. 4. Energy Harvesting An interesting side note, and not really a problem, in fact it is a benefit. Your catching system could use the incoming space craft to generate electricity in the form of the world's largest electrical generator. As the spacecraft passes through the electromagnets it could be used to generate a charge. The resulting charge could then be used to launch other spacecraft significantly reducing energy costs. (It wouldn't be 100% efficiency, but with a system this big, every Joule counts.) Happy world building! [Answer] There is an additional reason why coil guns don't scale up to high speeds that is seldom mentioned. Let's start by taking a quick step back and saying what a coil gun is. A coil is a big loop of wire. We have a metal projectile moving at some speed towards the hole in the middle of the coil. We run a current through the wire. This creates a magnetic field which pulls the projectile towards the center of the coil, speeding it up. When the projectile is through the coil we turn the current off, because we don't want it to be pulling the projectile back towards the coil. We then build many stages so that at each stage the projectile is sped up a certain amount. The problem therefore is: * Current has to be as high as possible, because the magnet pulls harder if the current is higher. * Current has to be on for precisely the right amount of time. Too short and you're not giving enough pull; too long and you're pulling backwards. The initial stages, where the projectile is moving slowly, are easy. It's the middle and final stages where the projectile is moving at several thousands of meters per second, that are tricky. If one coil is a meter long then the object is in the coil for less than a millisecond, and thus we need to trigger a high current very precisely. So think about how to do that. We have technology in our computers for triggering extremely small currents down to a fraction of a nanosecond and we can put billions of them on to a tiny silicon wafer. Now think about how hot your computer gets when manipulating those extraordinarily tiny currents. This is the technology you want to scale up to the point where the currents are equivalent to the current draw of a small city. High speed switches are made out of semiconductors. They're by design not perfect conductors, so they make heat. If you work out the math, the heat sink you need to keep the on-off switch of each stage of your coil gun from melting is enormous, and sheer amount of semiconductor material you need for what would easily be the world's biggest transistor is unfeasible at today's prices. For one stage; and you'll need thousands of stages. In short: the electricity that powers a big coil gun is cheap and readily available at scale; it's the electronics in the control system that we don't at present know how to scale up to the currents required to attain space vehicle speeds. [Answer] Must admit I've been toying with a similar idea, except at interplanetary scale. The huge advantage is that you are free of rocket equation constraints. As all the energy is delivered externally, you don't have to hand wave about [Bussard Ramjets](https://en.wikipedia.org/wiki/Bussard_ramjet) and the like. The presence of a catcher is also required, unless you are going to try and carry all the fuel for the slowdown phase, which pretty much defeats the point. If you are doing that then you might as well have a detachable 'acceleration phase' stage. So what are the problems: 1) As mentioned above, massive sustained acceleration, unless you have an amazingly long rail gun assembly. In a zero-g environment, a structure that is 100s of km long is not impossible. I would presume that in a zero-g vacuum environment a barrel would not be required, if your magnets can keep the projectile going straight. Indeed, at the speeds involved a physical barrel would just be a hazard. For the payload, you'd have to go beyond acceleration couches. Think [full immersion in a fluid](https://en.wikipedia.org/wiki/Liquid_breathing) (no air gaps, even in the lungs or ears); possibly freezing solid. You want to avoid any density contrasts within the ship in the acceleration/deceleration phases, to allow for the 100+g loads. Once in cruise phase, you could come out of vitrification. 2) Safety - Well.. you've accelerated a ship weighing hundreds of tonnes or more to, perhaps, 1000km/s. Going by the kinetic energy formula, e = 0.5\m\v^2, that would be ~10^17 J According to the Wiki, that's about a [Tsar Bomba](https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy))). So if anything goes wrong and you hit a planet (never mind a KBO) you will leave a noticeable dent. Even under good conditions, your catcher has to dissipate that amount of energy in a very short time. You'll need some very, very big capacitors. 3) Practicality - As long as the system is reliable and the energy requirements are solved, then it avoids sending huge fuel tanks out on long, tedious orbits. So in many ways better than chemical rockets or [solar sails](https://en.wikipedia.org/wiki/Solar_sail). It also requires some form of hibernation/sleep tech, as above. 4) Orbital Paths - You would probably need some form of adjustment onboard, but the calculations would be pretty trivial. You'd also want adjustment thrusters in case space junk was detected en-route, as collisions at cruising speed would be very very dangerous. [Answer] The concept of interplanetary travel by railgun isn't entirely feasible. When O'Neill and his associates were developing the concept of L5 space habitats they experimented with mass drivers as a method of launching vehicles. They discovered that there was a limit to the maximum velocity mass drivers or as here gauss cannons could attain. At higher velocities the vehicles wreck their electromagnetic launchers. This limiting velocity was 4 km/s. Now vehicles could be launched from orbit to this velocity. The vehicles' velocity, due to the gauss cannon, can be added to its orbital velocity. vehicles could be launched from an earthlike planet with a velocity of 12 km/s. This does produce feasible interplanetary travel. The travel times will be fairly long. Six to eight months travel time to planets in the equivalent of the orbits of Mars and Venus in your hypothetical solar system. Upwards of many years for travel to other planets. It will work but it will be slow. This form of travel is roughly on a par with chemical rockets. But fusion, plasma and ion drives will perform better and faster. [Answer] # Have some numbers! Okay, so I don't know how to make numbers look pretty, so I'll be using code blocks :( Also, for the sake of having some real numbers to work with, I'm going to assume a nice simple trip from Earth to Mars at the point when they are closest together. All numbers are taken from [NASA](https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html). ``` 30g = 300 m/s^2 delta-v mars-earth = ~5,000 m/s minimum distance mars-earth = 55,700,000 ``` So first of all, how long is this gun going to have to be? You said about a minute, so I'll give numbers for 60 and 120 seconds. For the rest of this answer I will continue calculations for each of these numbers, the first being the craft accelerated for 60 seconds and the second being the craft accelerated for 120 seconds. ``` d = vi * t + 1/2 * a * t^2 d = 0 + 1/2(300)(60^2) = 540,000 m d = 0 + 1/2(300)(120^s) = 2,160,000 m ``` How fast does this get us? ``` v = vi + a * t v = 0 + 300(60) = 18,000 m/s v = 0 + 300(120) = 36,000 m/s ``` Plus the 5000 m/s perpendicularly from the difference between Mars' and Earth's orbits gets us: ``` sqrt(5000^2 + 18,000^2) = 18681 m/s sqrt(5000^2 + 36,000^2) = 36345 m/s ``` At the point that the craft passes Mars. How long does this trip take us? ``` t = d / v t = 55,700,000/18,000 = 3094s t = 55,700,000/36,000 = 1547s ``` So how much energy are you going to need? For this we need the weight of the craft. You said we need to be able to perform an orbital injection, so the rocket equation is coming into the picture! (YAY!) WolframAlpha has a nice tool built-in for the rocket equation, so I'm going to [give all the numbers to it here.](http://www.wolframalpha.com/input/?i=rocket+equation&rawformassumption=%7B%22FS%22%7D+-%3E+%7B%7B%22RocketEquation%22,+%22mi%22%7D%7D&rawformassumption=%7B%22F%22,+%22RocketEquation%22,+%22vi%22%7D+-%3E%225+km%2Fs%22&rawformassumption=%7B%22F%22,+%22RocketEquation%22,+%22ve%22%7D+-%3E%225+km%2Fs%22&rawformassumption=%7B%22F%22,+%22RocketEquation%22,+%22vf%22%7D+-%3E%2236.3+km%2Fs%22&rawformassumption=%7B%22F%22,+%22RocketEquation%22,+%22mf%22%7D+-%3E%221000+kg%22). I assume a (very light) dry mass of 1,000 kg and shoot to do nothing more but get the craft below escape velocity of Mars. These are the initial masses we get: ``` m0 = 15,180 kg (for the slower craft) m0 = 523,219 kg (for the faster craft) ``` Now how much energy will it take to get these crafts up to speed? ``` E = 1/2mv^2 E = 1/2(15,180)(18,000^2) = 2,459,160,000,000 J E = 1/2(523,219)(36,000^2) = 339,045,912,000,000 J ``` Actually the energy requirements aren't as horrible as I had imagined, but a 500 km long gun seems pretty ridiculous to me. Play with these numbers as you see fit to try and figure out what works for your story! ]
[Question] [ Let's say Earth started rotation in the opposite direction without any catastrophic events, would a day on Earth be shorter or longer or just the same considering that speed of rotation and revolution stays the same? [Answer] # Depends on how you define "day". There's two definitions of a "day". There's the Solar day, the time between the Sun being at its zenith. And there's the [Sidereal day](https://en.wikipedia.org/wiki/Sidereal_time), the time for the Earth to rotate 360°. They are not the same. *The Solar day is affected by the direction of rotation, the Sidereal day is not.* [![enter image description here](https://i.stack.imgur.com/eiw28.png)](https://i.stack.imgur.com/eiw28.png) [Source](https://en.wikipedia.org/wiki/File:Sidereal_time.svg) A solar day is 24 hours. This is because the hour is 1/24th of the time it takes the Sun to return to its original position in the sky (almost, see below). A sidereal day is a bit shorter, about 23 hours 56 minutes 4 seconds. This is because the Earth's movement around the Sun means it has to rotate a bit further to have the Sun at zenith. If a planet both rotates and revolves in the same direction, as the Earth does, the solar day will be longer than the sidereal day. If they revolve in opposite directions, the solar day will be shorter than the sidereal day. The Sidereal day remains the same, it is only affected by how fast the Earth rotates. Right now, the Solar day is 3 minutes 56 seconds longer than a Sidereal day. If our rotation were reversed, it would be 3 minutes 56 seconds shorter than a Sidereal day. *A solar day would be 23 hours 52 minutes 8 seconds. For a total loss of 7 minutes 52 seconds. Note: Because the Earth wobbles a bit in its rotation, and other factors, the position of the Sun in the sky is not an accurate way to define time. [A second, and thus an hour, is now defined as the time it takes for 9,192,631,770 wavelengths of the light released when a Caesium 133 atom transitions between two states to go past](https://en.wikipedia.org/wiki/Second#International_second). It does so in a very precise, fixed amount of time. The number of oscillations was chosen to keep a second a second and hour an hour, but a solar hour will fall out of sync with an SI hour. [Answer] ## Yes...but not by a lot This has been looked at a little [over on physics SE](https://physics.stackexchange.com/questions/29235/would-it-matter-if-the-earth-rotated-clockwise). Start off by imagining the earth doesn't rotate at all. [![Light on Earth](https://i.stack.imgur.com/jXXB4.png)](https://i.stack.imgur.com/jXXB4.png) We get one day every 365 days with the day/night boundary moving as below: [![Day/night boundary](https://i.stack.imgur.com/DHV5A.png)](https://i.stack.imgur.com/DHV5A.png) This is key. The earth is going to have a "day" whether it rotates or not. Now we choose whether we rotate with or against this day by saying whether the Earth rotates in the same direction or not. Currently we rotate with our orbit and the effect contributes to the day length. If we were to rotate against it the effect would act against the day length. As shown below: [![Illustration of day length differences due to orbit or rotation](https://i.stack.imgur.com/19zfX.png)](https://i.stack.imgur.com/19zfX.png) So we can see an anti-clockwise rotation is added to by the orbit-day whereas the clockwise one works against the orbital "day". The time it takes the Earth to rotate once about it's axis (regardless of direction) is called its "sidereal day"*. The combination of the sidereal day and the orbit day is called the "solar day". This being said we would get shorter days only by about 8 minutes** (the difference being that the rotation is about 365 times quicker than the orbit day). ]
[Question] [ I got inspired by reading all about the Directed Energy Weapon programs. What would happen if you could crank up this concept to eleven? Please assume energy is not a problem. You have 'superbatteries' (please consider energy not relevant for this question). They are powering a handheld microwave gun, about the size of an assault rifle. The power output should be several orders of magnitude higher than current DEW systems. * with energy out of the way, would this size be feasible for a really powerful gun? * Is it possible to focus microwaves into a rather narrow 'beam'? * With abundant energy, what is the effect of microwaves on human body, armored or naked, on tanks, buildings, etc.? * When maintenance / resources are not relevant, would this gun be really more useful than a modern assault rifle? Edit after first answer: * I am looking for really advanced stuff (hence the sci-fi tag), not today's technology level * Is enough energy able to overcome the metal and water weakness (as in thucydides answer) of microwaves or is that just a physical limitation? [Answer] The US Army has the "Active Denial System", which is a truck mounted microwave projector that should serve to illustrate the effects such a weapon would have. The ADS uses a large projector to send a beam of microwaves at 95 GHz at the target. This wavelength was chosen since the ADS is a non lethal system and the high frequency beam only penetrates @.04mm into the skin, while a conventional microwave beam (such as a microwave oven) can penetrate to a depth of 17mm. The effect is reported to "feeling like you have been set on fire" when volunteers are exposed to the beam, and the feeling reportedly ceases when you exit the beam. Crowd control and dispersal is the goal of this system and people fleeing the effects of the burning sensation would stampede the crowd away from the projector. [![enter image description here](https://i.stack.imgur.com/6IIxP.jpg)](https://i.stack.imgur.com/6IIxP.jpg) The illustration demonstrates one of the issues with beam weapons of any sort (including lasers), the need for some sort of focusing optics to aim the beam at the target. Since microwaves are much longer than optical wavelengths used in laser weapons, the ADS has a correspondingly larger emitter. A hand held microwave weapon would have to have a large "dish" on the front in order to be effective, with obvious effects on soldier performance trying to move tactically with a large dish to project the microwave beam. Microwaves are also affected by the atmosphere (like lasers as well), with the particular issue that microwave beams are easily absorbed by water (which is how microwave ovens work, after all). Rain, mist and even high humidity would affect the propagation of the beam. Finally, microwaves are absorbed or reflected by metal. Putting a spoon in a microwave oven demonstrates the effect when the emitter is close by, but metal mesh woven in the fabric of uniforms or even the proverbial "tin foil hat" will serve to protect the target from microwave beams. Microwave weapons could have a place on the future battlefield, both as crowd control/crowd dispersal devices in urban environments and in [COIN operations](https://en.wikipedia.org/wiki/Counter-insurgency), and perhaps more importantly, as anti air devices to disable enemy drones and UAV's by interfering with the control signals. [Answer] I will focus on just one aspect of your question. The ability to focus a microwave depends on the size of the "lens" (reflector) compared to the wavelength. If you intend to use the wave to "cook the enemy", you will want to use a frequency of a few cm (the shorter the wavelength, the more local the damage will be to the surface). But the problem is that you will need a very large dish to get a sufficiently focused beam. The angle (in radians) of spread of the beam is a result of diffraction, and roughly given by $$\alpha = 1.22\frac{\lambda}{d}$$ where $\lambda$ is the wavelength and $d$ is the diameter. So if you want to focus the beam to a point the size of a head (20 cm) at a distance of 100 m, for a wavelength of 3 cm (10 GHz) you would need a diameter of 6 meters. Not really "hand held" any more. Make the wavelength shorter, and you will have less ability to penetrate (you would take off the skin, but not kill). [Answer] You could not use a conventional focused microwave beam because you'd need a very large antenna dish to do that. Granted, you could imagine a nanotech dish deploying very quickly when shooting - sort of a large umbrella opening. But that's unwieldy. You would need very advanced metamaterial technology to build a linear, room-temperature MASER amplifier in the shape of a barrel. Once you have that, you also need very efficient transducers and very powerful supercapacitors (you can do with current technology but you need a handle like a battery drill and God's own heat exchangers, or large parts of the device would melt or catch fire). Finally you're left with Flash Gordon's ray gun: a pencil-thick MASER beam that will cook anything in its path, unless protected by a conductive shielding. Given that there'll be Joule energy transfer, the shielding can't be just aluminum foil, you need something like copper (or even better, silver) mesh chain mail. In practical terms it's not very much better than a bullet gun, and in several ways, it's worse, except perhaps somewhere you can't risk perforation damages or splinter ricocheting: * the weapon is line-of-sight, very much like a bullet gun. * no traces are left except on the victim - no powder smears, gases, spent cases or anything - and the noise is probably reduced. Unless the MASER bolt triggers some kind of sonic boom, not unlike the thunder from a lightning discharge. * it can only shoot a few shots before you need a fresh battery (magazine). * the range is limited. Not affected by wind and droop; but fog, rain and heat haze might be an issue. * shielding is much easier than against a solid bullet On the other hand, time to target is negligible, so you could have some kind of friend-or-foe autotargeting system and actually make it work. Also, shape recognition could allow "impossible" shots - just wave the gun in the general direction of the target, and, provided it ever gets aligned, even for a millisecond, the gun could successfully shoot the victim through an eye. Defensive shields could feature wide-spectrum face simulations to thwart this approach, though. [Answer] The military is looking into a hand held MW weapon in the near future. > > "While larger devices will be mounted on ground or air vehicles, some smaller devices will be hand held.(79)"[1] > > > > > "The real question is what all these technological developments mean for future warfare. To try to answer this question as completely as possible, we will look at a future scenario in the 2020-2030 timeframe."[1] > > > > > "Finally, the size of microwave weapons will depend upon the target, delivery application, and desired effects, and thus microwave weapons are well suited for covert military operations. It is conceivable that “hand-held” missions could employ a system that weighs less than ten pounds."[2] > > > References: [1] Geis, John P. (2003, April). Directed Energy Weapons On Battlefield: A New Vision For 2025. Retrieved (2018, Oct. 4). dtic[mil]. Available from: <http://www.dtic.mil/dtic/tr/fulltext/u2/a463429.pdf> [2] Walling, Eileen M., High Power Microwaves; Strategic and Operational Implications for Warfare, Center for Strategy and Technology Occasional Paper 11, Maxwell AFB, AL, p. 7. Available from: <https://pdfs.semanticscholar.org/f579/e74e39dbe7ac33a952c8c3c2382426e93f13.pdf> ]
[Question] [ Or how can you modify (temperature, pressure etc.) of hydrogen or a different gas to get more "lift" in airships, if that's even possible? [Answer] Hydrogen is the lightest gas there is. In its common diatomic form (H2), it consists of two protons and two electron, making it extremely light, even compared to the next lightest gas, helium (although [the difference in lift between them is minimal](http://www.airships.net/helium-hydrogen-airships)). There's nowhere better you can go, unless you choose to simply use Hydrogen-1. Plus, if you heat it up a bit, then - just as with hot air - it will provide more lift, as per the ideal gas law. Okay, fine. You could go with a pure or partial [vacuum](https://en.wikipedia.org/wiki/Lifting_gas#Vacuum) (see also [here](https://en.wikipedia.org/wiki/Vacuum_airship)), but this is typically considered difficult because of the extreme pressure difference between the inside and the outside. However, [it has been considered](http://arxiv.org/abs/physics/0610222), and has a chance of providing at least some lift. But stay with hydrogen, if you're willing to put up with the risk of ignition. Did I mention that hydrogen is really explosive? [![](https://upload.wikimedia.org/wikipedia/commons/8/84/Hindenburg_burning.jpg)](https://upload.wikimedia.org/wikipedia/commons/8/84/Hindenburg_burning.jpg) Image of [the Hindenburg disaster](https://en.wikipedia.org/wiki/Hindenburg_disaster) in the public domain. [Answer] Not really. The lift is not actually provided by the lifting gas, it is provided by the air it displaces, so lift can't exceed air density. The lifting gas simply provides the pressure to sustain an air displacing structure with large volume with minimal mass. The differences in lift between lifting gasses are actually simply the differences in the weight they add. Helium and hydrogen are already fairly light, so it is difficult to replace them something that weighs significantly less. [Answer] you could heat the gas within the bag, but this has a few problems. first, it makes it harder to contain the gas. this is especially true for hydrogen, which already is almost impossible to totally contain without leaks; which is a problem, because you would presumably want to use the lightest gas that you could. the obvious solution here: hot vacuum balloons [Answer] If you're willing to get a little weird with your physics, nobody I know of has ever proved that negative mass isn't possible. I.e. matter that is gravitationally repelled by positive-mass matter and attracted to other negative-mass matter like a magnet. We've never found any (and how would we? Any that was still left in the Milky Way when it formed would be heading out faster than we could catch it!) but it's ability to 'fall up' would give it greater lifting power than any positive-mass gas. [Answer] I thought of plasma. Not a gas, strictly speaking and, when researched on it, it happens to be discarded in [the WP article about this topic](https://en.wikipedia.org/wiki/Lifting_gas#Plasma). You would need an elastic material that resists the huge inside charge (avoiding ions to get electrons or electrons being got) just to get a slightly higher lift. > > Plasma > > > Another medium that in theory could be used is a plasma: ions > repelling each other could give a pressure intermediate between vacuum > and hydrogen and hence that counteracts the atmospheric pressure. The > energy and the containment requirements are extremely impractical, so > that it may only be interesting for science fiction. > > > Vacuum is not a gas either, but all you need is a [extremely light, airtight and rigid material](https://www.youtube.com/watch?v=0i4tNUx1a1M). Anyway, both solutions would be even more (much much more) dangerous than hydrogen. Any tiny crack in the cover would result in a huge instantaneous and devastating ex/implosion. And, of course, you also have the theoretical [negative mass](https://en.wikipedia.org/wiki/Negative_mass) that nobody can be sure how would behave, what framework and energy order of magnitude you would need to handle it, how to get it or even if exists. TL;DR: your biggest problem isn't the filling, but the container. Any society with the knowledge to make such a floating device would have for sure the technology to fly in a faster, cheaper and more secure way. [Answer] The only thing lighter than hydrogen is... [a vacuum airship](https://en.wikipedia.org/wiki/Vacuum_airship). That's right, you can evacuate all of the air inside your aircraft to make it even more buoyant, but the problem is that the outside atmosphere will be pushing in with 14.7 psi so you will need a very strong air-frame to resist that force. Very strong air-frames are also very heavy... But! The [square cube law](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law) actually can come to the rescue here. As you scale the aircraft up, the volume of vacuum increases to the third power, while the surface area you need to build only goes up by the second power. This means there's a certain point where you can build a vacuumed out airship that will actually fly, despite its tremendous weight. ]
[Question] [ I'm trying to find explanations for a strain of beans (or any other food-producing plant) that have become large, maybe as large as most trees, and about as wide in girth, that overgrows countries into huge bean-filled forests. I started by saying that a larger strain of plant had been selectively bred (Not GM, please! That's far too generic!) to be large as bush, strong, able to grow anywhere, and have enormous yield. I chose beans specifically because their produce can be used for both food and replanting. I then imagined that, because of the plentiful seeds, these large plants began to grow in undesired places, and, by very unlucky natural selection after overuse of weed-killers, another strain of larger size and weedkiller resistance evolves. ... and that's when I hit a dead end. I can't find an explanation for any further growth than much more than a bush. What other reasons might there be for accelerated growth of these plants? Also, is there another, more suitable plant that could grow to huge sizes? Note: I may have said earlier, but I really want to stay away from dull, generic explanations such as "Nuclear radiation" or "Genetic modification". I'd like to explain this in terms of natural laws such as evolution or survival of the fittest. [Answer] Invasive Beans It's unlikely that human selective breeding would produce a bean plant that was able to dominate the natural environment of that bean plant. In general, human selective breeding tends to produce things like exceptionally large seeds, a trait which is a detriment towards survival in the wind, given the increased energetic costs of producing these seeds. What would be far more likely is that humans would find some incredibly productive bean plant that grows in a far off corner of the world, fall in love with its delicious beans, and transplant it back to their home nation. Luckily for the farmers, this new bean grows great in the local soil! Unluckily for everyone else, this new bean grows great in the local soil. A few years later, as the beans grow over all of the native trees and crush/smother them, the people who brought them back realize that they have made a mistake. All of the forests around their homes now look like this: ![kudzu weed covering native American trees](https://i.stack.imgur.com/FchXZ.jpg) That, of course, is a picture of runaway kudzu in the United States. While it behaves itself in its native environment, without the seasonal dieback and predation that it experiences in its native environment, it's become a noxious weed. Your beans could likewise be such an invasive species. They've evolved thick, woody, treelike stems because their native environment is too cold and rocky to allow the growth of deep root structures. These stems allow the green bits of the plants to grow back each summer, at the end of which they (normally) die back heavily in the face of a long, cold winter. Now, due to the deliciousness of these cold weather bean plants, they've been transplanted to somewhere warmer. Of course, in this warmer climate, the beans don't experience any dieback, and starving winter deer don't come along and nibble back all of their new growth after all of the other plants are covered by snow. They grow like it's summer year round, irrespective of what sort of soil there is because they evolved to grow in some of the worst soil on the planet. They also produce beans year round, which made them a great food crop. The beans are tasty, at least, which is good, because now they're about the only thing anyone has to eat. [Answer] Rather than basing your experiment off of a plant known for giving good fruit and trying to select for its properties, consider a different approach: <https://en.wikipedia.org/wiki/Bamboo> Bamboo isn't much of a plant, but a grass. And not just any grass, but the fastest growing plant in the world. It can grow up to 75cm per day under good conditions, which is insane. (That means it can go from cut to the ground to over your head in less than 3 days. Try keeping up with your lawnmower!) It makes for an amazing building material (very sturdy stuff, like wood) which is one of the things it's most used for. With the incredible growing speed and its sturdy nature, bamboo is known to be capable of growing through other constructions and plants. So even as it stands, trying to keep it contained is already challenging. A field that can regrow overnight, made of a really tough wood-like material is already a hassle to contain. But it also flowers. According to the wiki article, the flowering period for a bamboo colony is somewhere between 60 and 130 years. And when it happens, they go big: the entire colony will sprout immense amounts of fruit in a few years time and then die out. And then new bamboo grows from the seeds that were produced. Now imagine that you manage to get it down from flowering every 60 years to, say, every 5 years by some random lucky mutations. Now you have a forest that grows from nothing to up to 30 meters high in a few months (and regrows in a few more months if you start cutting it down) and every few years there will be a massive bloom of fruit, the entire forest will die (read the article for some of the terrible consequences such as a massive increase in rodents and subsequent famines and diseases) and then next season the forest will grow back and it'll have become substantially larger. (If the ability to eat it is somehow important to the story, humans can prepare and eat the stems, although that's not the primary use of it) [Answer] Fire resistance; fastest way to level a field is to torch it. However that doesn't touch the roots and in the after math the quickest growing plants able to sprout again from just the root (like many grasses) will sprout up first and push out the slower growers. Other naive methods of trying to eradicate them is cutting it all down. Again a fast growing plant that can sprout from roots will dominate the field quickly after. For increased unwanted spreading of the plant you can make the seeds survive in the digestive tract and sprout from the droppings of herbivores in the manure pile. They also seem like a tasty additive for cat and dog food though again viable seeds will pass through intact. Local wildlife can also partake in the spread. Before long local fields, woods and backyards will start sprouting the plant, signaling the start of the burning/chopping and weedkiller. [Answer] Most plants that grow foods are [herbaceous](http://en.wikipedia.org/wiki/Herbaceous_plant), meaning that they have supple stems and die each year, but also that they generally grow relatively fast. Herbaceous plants focus their growth on fruit production at the end of each season. Trees have woody, stiff stems, which allows them to grow taller and survive multiple seasons. They generally grow slower. Trees focus on long-term growth and fruit production is not as important. So plants that stay small and focus on fruit production are good for people food. Plants that focus on growing large don't have excess energy for large-scale fruit production. You're going to need a very specific combination of factors to make this happen. A specific kind of GMO: a tree that has been designed to have the characteristics of an herbaceous plant like fast growth, but later grow stiffer cell walls to help it stay strong and survive multiple seasons (think of tomato plants - they get very large, but crawl or must be supported). A very specific food source: high-density energy sources, either from a very very sunny area or special mineral deposits. But, it's going to need to be in the tropical latitudes. Up in the north there just isn't enough sun to facilitate fast plant growth. ]
[Question] [ Would it be possible to make a custom zoomable world map (kinda like google maps), where you can have all the cities of the world but are able to zoom out to the whole world (and no longer see the cities). What programs could I use to make such a map? [Answer] AlexP is right of course, you should ask on a geography stack... but that can be daunting/overkill. The main thing to understand is that worldmaps have too much detail to load at the same time. So they (practically?) all divide the world in "tiles" of increasing resolution --- say the world in a Mercator projection as 1x1 tile (so about 40K x 20K km), then 2x2 (each a quadrant/half-hemisphere), 4x4, 8x8, ... , 1024x1024 (still 4x2 km), ... up to whatever resolution. You can change coordinate systems but you will want to stay with the default/ what people are used to. [In reality of course it's square tiles.] You can choose to limit movement or instead scroll around the world infinitely East-West (not North-South across poles, typically). The way it works is you get a few tiles (say 2x3, or 12x8) fully displayed on your map plus partial ones on the edges, and it dynamically loads in tiles in the direction you are scrolling. If you zoom in/out one or more steps, it hasn't pre-loaded any so may hesitate a second. Now the interesting thing are the map suppliers: Openstreetmap is well-known, but e.g. Stamen makes striking ones ("toner" stark black/white maps, my favourite "watercolor" one). Keep in mind there's local ones (say, cycle paths of Switzerland) you can use globally and not see much in most places. The thing is that maps are many layers: a geographical one (e.g. satellite-based suggesting vegetation and height, or political boundaries), one of name-labels (in local language/script, or French, English, ... ), zero or more of "fixed" features (roads typically, or buoys on a seamap; landmarks on a landmarks map), zero or more of "data" features (current weather, local voting results as a choropleth, GDP by county or country, ... ). You can make your own "tileset" of a fantasy planet, or somewhat abuse it to display a gigapixel image of an artwork you have [see 'non-geographical map']. I vaguely remember a tutorial of taking a 19th century map (of I think Buenos Aires) and generating the tileset; there's also providers like Arcanum.com or the National Library of Scotland who have done the work with historical maps. I personally use LeafletJS for all my maps. It gives you all the usual functionality, and you can choose what map to move around on, what coordinates and zoom-levels to limit to, etc. There's a good Leaflet Providers Demo page to easily compare, to see what layers you want to combine (a satelite map with country & city labels plus current cloud cover? Just the Stamen Tones outlines without labels?). You will have to be able to use Javascript if you want to add features (mostly options turned on/off in the right places, and filling in your own location coordinates) or advanced interactions; but what you describe is just copy-pasting from given examples. [Answer] This kind of applications are called [Geographic Information Systems](https://en.wikipedia.org/wiki/Geographic_information_system) (GIS). The Stack Exchange network has a dedicated stack, appropriately named [Geographic Information Systems SE](https://gis.stackexchange.com/). One of the best known GIS applications is [ArcGIS](https://en.wikipedia.org/wiki/ArcGIS); of the free and open source GIS applications, I would say that the best known is [QGIS](https://en.wikipedia.org/wiki/QGIS). Wikipedia has a [comparison list](https://en.wikipedia.org/wiki/Comparison_of_geographic_information_systems_software) of GIS applications. If you don't really want a full-blown GIS suite, there are many free web-based applications more-or-less suitable for the creators of fantasy worlds. One of the most commonly used is [Azgaar's Fantasy Map Generator](https://azgaar.github.io/Fantasy-Map-Generator/) a.k.a. Azgaar's FMG. It is very much simpler than an actual GIS suite, but gets most of the job done quite nicely. [Answer] Google Maps at least used to have a feature that allowed you to use their entire feature set with your own geographic database. I recall this was actually done for the MMO game [There](https://www.there.com) (for their online map of There's world); this started no later than around 2005 (might have been earlier; There opened in 2003). ]
[Question] [ Humans want to build a Dyson sphere around the Sun. They have noticed that Ganymede's icy composition would be perfect for mining to get the icy resources needed to build the sphere, or Mercury could be used due to its silicate composition. However, they do not want to remove the moon itself as to avoid these scenarios: > > Ganymede, aka Jupiter III, was the largest moon in the solar system, until space mining removed its existence. > > > > > Mercury was the smallest and nearest planet to the Sun, but due to space mining, Venus is now the first planet from the Sun. > > > Would it be possible to preserve the astronomical significance of various celestial bodies while supplying the vast amounts of resources needed to build a Dyson sphere? What alternate methods could be used? I suppose asteroids and KBOs could be used for this as asteroids would supply the metals and the KBOs would supply ices, but the large distance of the KBOs would make construction very cost-ineffective. [Answer] ## Leave your moons in peace, harvest some nearby stars As with all of Dyson's inventions, we'll have to hand-wave how it has to be produced anyway.. Any moon, or even planet Earth would be irrelevant, you may as well preserve it Volume of a sphere: V = 4/3 πr³ Volume of a hollow sphere: V = 4/3 πrOuter³ - 4/3 πrInner³ Where rOuter-rInner = thickness of your Dyson sphere. Now suppose you'd rotate your Dyson sphere, the hull would need to provide support, not mass. In order to get a safe Dyson sphere, and a minimum of one km thickness (1000m) will do, with a density of say 3gr/cm (part is metal) you'll still need a giant amount of matter, when your Dyson sphere would be a solid construct (not "sparse") Calculation example Suppose you'd take the Earth orbit as a guideline for its size (less hot and more convenient would be Mars, so take Earth's orbit as a minimal radius r1) you would get 1 AE = 149 597 870 700 meters radius, which yields a total volume of 4.2e34 m³ For the Dyson hull, subtract like in above formula. You'd still need 8.43e26 m³ which is a few orders less of course, but assuming we need an average density of 3.0gr/cm³, you'd still need a mass of 2.531e+33 grams according to my calculation. To build that thing, you'd need 2.531e+30 kilograms of material. The total Solar system including the sun [has a mass](https://www.quora.com/What-is-the-total-mass-of-all-the-objects-in-the-solar-system) of 2.1e+30 kg. The sun itself has a mass of 1.9e+30 kg, so if you want to keep it, you're left with 0.2e30 kg of building material. Conclusion: if you could harvest ALL MASS in the solar system except the sun, you'd have less than 10% of the material required.. so you'll have to set up some interstellar transports anyway, to import the material required ! Make the Dyson hull as thin as technologically feasible.. Say, you repeat the calculation for only 100 meters thickness, the required mass would be in the order of 10e+29 kg, still more than a million times the moon mass. But a hull weighing 10e+29 kg could (theoretically) be built by shredding our gas giants Jupiter and Saturn. Solid or sparse, Dyson shell or Dyson swarm A Dyson sphere harvests energy of a sun, that is its intended purpose. Inhabitable Dyson spheres are fiction. A solid shell was first named by Dyson, but after that, he ensured his public that a solid sphere could never be constructed. The shape of the megastructure would be rather look like a swarm, like [![enter image description here](https://i.stack.imgur.com/5CORz.png)](https://i.stack.imgur.com/5CORz.png) [![enter image description here](https://i.stack.imgur.com/8B6qT.png)](https://i.stack.imgur.com/8B6qT.png) The two differ in the way each "solar cell" would move. In the left case, everything is in orbit, only harvesting the energy. In the right case, propulsion is needed, which can be provided by the solar radiation itself. On the right, each satellite is stationary in space. Material will be less of a problem, but you'll have to crush some moons to build it. The location - to start - could be between Mars and Jupiter, the asteroid belt, creating an Dyson ring from available material. Mars' moons Deimos and Pheibos can crushed first. Then some of Jupiter's moons.. the ring will take shape in a few centuries.. <https://en.wikipedia.org/wiki/Dyson_sphere> Materials Notice that the Wiki-topic does not mention materials or "metal". When I proposed to use gas giants and stars to gather the mass needed, I ignored the fact that material for a solid Dyson sphere should be solid, or solidified, in some way. You could hand-wave that, but this is a science based topic. To gather the energy, you'll need metal parts How much metal would be needed and where harvest that.. Suppose you'd like to have cables connect each spoke of the above Dyson swarm of solar cells, gathering the energy. A radius of 1AE, circumference will be C = 2πr = 2 \* 149597870700 \* 3.14 = 939 951 143 167 meters cable per spoke ..suppose you'd need a cable of 1cm in diameter, that is 0.0003 m2, you'd need V = πr2 \* C = 0.0003 \* 939 951 143 167 = 281 985 342 m³ metal per spoke. Using iron, amounting to 7873 kg/m3 times that amount when it's iron: 2 220 070 605 tons. The Earth's yearly total production of iron in 2015 was about [half of that amount](https://en.wikipedia.org/wiki/List_of_countries_by_iron_ore_production), let's go for it.. we can do it now. Far future In the (far) future to construct a true, solid inhabitable Dyson shell like Star Trek shows us, like a giant armored inhabited sphere around a sun, humans could consider to go harvest iron in a supernova.. in a certain stage of a supernova, a massive amount of iron will be produced. Maybe the supernova could be stopped just before it occurs ? You'd have a giant solar core consisting of iron. <https://futurism.com/what-happens-when-stars-produce-iron> [Answer] Have you ever seen what happens when an historically significant building needs to be renovated? [![enter image description here](https://i.stack.imgur.com/2hywS.jpg)](https://i.stack.imgur.com/2hywS.jpg) You demolish the inside and leave only the outside, so that the appearance of the building isn't changed. You people can do something similar: they can leave a shell in place, to keep intact the appearance of the celestial body, and mine the inside to get all the needed material. [Answer] Celebrate the origin of the sphere with the sphere. The sphere will be called the Cupid sphere. It will be asserted to be the direct descendant of Mercury - made of Mercury stuff and occupying the place of honor by the Sun. Mercury will have taken the next step in its evolution, begetting the Cupid Sphere. Cool things about the Sphere will be placed in the context of cool things about the planet. Some pieces of the sphere will be unmodified Mercury bits as a paean to its provenance. You all like that "paean to its provenance"? People who mourn Mercury will eat that stuff up. Because the truth is, Mercury is not much involved with day to day affairs on Earth, and people bothered by its loss are ideas people. Those people are also comforted with ideas, and so the sphere makers will meet them where they are. [Answer] ### Replace the mined material with something else Nearby bodies (Jupiter resp. the Sun) have a lot of hydrogen. You'll need a nuclear fusion device to make material that's solid at those temperatures (especially in the case of Mercury), and perhaps some combustion as well, but that can probably double as a propulsion for your spacecraft. [Answer] ## Import all your materials from other solar systems As mmomtchev comments, the mass of the solar system isn't actually that much when you remove the sun from the equation. It's hard to overstate how ridiculously massive such a structure would be! Realistically to build a Dyson Sphere you'd need to strip the entire solar system and several of its neighbours for raw materials. You're going to need materials from at least one other solar system anyway, so use that same technology to fetch all your materials from elsewhere and leave the planets and moons you care so much about entirely alone. Given the obvious gravitational impact of introducing a whole solar-system's worth of material into an existing solar system, you may want to build your Dyson Sphere elsewhere too. [Answer] > > What alternate methods could be used? > > > There are many(at leas more than one), including bulding dyson swarm, or if you like it to be a shell, then to build one which is enough and suficient for purposes of extracting energy, collecting energy for a star (it can be in form of statites as an example, or active supporting structures - some suitable approaches to make a shell of that size) As mentiont in one of the answers, a correct feasible thing is Dyson swarm, and it has the purpose to collect energy of a star, meaning it is a tool for such collecting. Correct tool with correct purpose. Then, if you use it that way, as a tool for energy collecting and conversion, then it does not require that much of mass of materials, 1 a.u. radius sphere, for energy collecting, with average mass of 1kg per square meter(it can be a solar panel if you have difficuties to imagine more efficient solutions, 1kg, by mass, solar panel in microgravity can be feasible with cirrent technologies) then the whole sphere requires about 5% of Venus mass for it - total. No planet dissapearing and such. Depends on major materials for structural elements, which can't be hydrogen, lol, as it was suggested in some answer, but, gas giants and the Sun itself can be sources of heavy elements as well, where they are persent in around 1% concentrations. It is a bit more sofisticated approach and technology, but it also possible. So one of the ways is - do not create unnecessarly problems, this way there is no need solving them. If solid dyson sphere is an actual goal, as massive epic construction with porpose to be epic and massive, it possible to do so with active supporting structures, (watch Isaac Arthur channel for explanations what it is) then borrowing materials from other star systems and stars is the way to preserve celestial bodies of this system, but it has a problem of changing orbits of those bodies is Solar system, because of additional mass of that sphere, it can be corrected but then orbit periods will change which is end game - wall of laws of physics of this universe or more advanced technologies .... So choosing goals in a wrong way leads to all kinds of problems. Is it impossible to squeeze water out of a rock?, eeehh not really, but yes it possible if you try hard(like converting matter and other transmutations as an example, which isnt scify, it just energy inefficient etc). So make right choices, and you will get proper results. Build Dyson Swarm it is epic and practical and useful. [Answer] It is even less than that: the solar system mass is only 1.0014 solar masses, Jupiter which is about 3/4 of the non-sun mass is at about 2\*10^27 kg - so you don't need anything but Jupiter and eventually Saturn. [![enter image description here](https://i.stack.imgur.com/BFfY8.png)](https://i.stack.imgur.com/BFfY8.png) No point bothering with the rest. One will have to really master ultralight materials - and their production from hydrogen - to make a solid Dyson sphere. But such a solid Dyson sphere is not really feasible anyway as it would be impossible to maintain it in place - gravity won't be of any help once you have completely surrounded the start and the tension forces will be on a yet unknown scale - far beyond any theoretical tensile strength limits. The only realistic project is the so-called Dyson Swarm - billions of small orbital elements with solar panels - which was the original idea of Dyson - it got extended to a solid sphere by not so-scientifically minded sci-fi authors. Dyson was an astrophysicist. ]
[Question] [ I want to create a glutton creature that can open its mouth wider than the prey item like snakes do, but also can bite through that big hard object and even chew it; this creature doesn't swallow prey whole but instead bites or chews the major part of it in a single bite. I want to know if this is possible and, if so, what the musculature/anatomy/biomechanism looks like. I feel this is a contradiction, but correct me if I am wrong and this is actually achievable or exists in real life. * It just has one mouth/jaw, so no double mouth like xenomorph in Alien movie or moray eel. * I am not asking about other methods to shred or chop off the big part (for example: crocodiles spin to bite off the meat chunk) * Its bite is large enough to encompass something like half of the prey's body, so no small bite to eat its prey. [Answer] Combination sudden gape and blades for jaws? Dunkleosteus! <https://ucmp.berkeley.edu/vertebrates/basalfish/placodermi.html> > > Placoderms bore heavy bony armor on the head and neck, often with an > unusual joint in the dorsal armor between the head and neck regions; > this joint apparently allowed the head to move upwards as the jaw > dropped downwards, creating a larger gape. > > > --- [Feeding mechanics and bite force modelling of the skull of Dunkleosteus terrelli, an ancient apex predator](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2373817/#!po=18.7500) [![dunkleosteus skull joints](https://i.stack.imgur.com/cTkpi.jpg)](https://i.stack.imgur.com/cTkpi.jpg) > > The central result of this study is that D. terrelli used this unique > four-bar linkage in the skull to achieve high speeds during jaw > opening and transmit extremely high bite forces to its prey during jaw > closing. Dunkleosteus appears to have had a rapid gape expansion, > going from closed jaws to peak gape in as little as 20 ms and > completing the feeding cycle in 50–60 ms... > > > Dunkleosteus also had one of the most powerful bites in vertebrate > history... These bite forces greatly exceed the bite forces collected > for all other fish species that have been reported and those for most > modern mammalian predators, including the spotted hyaena... The only > reports of higher bite forces are those found in some extremely large > alligators and dinosaurs. > > > Dunks here could gape wide because not only could it swing its jaw down, it could swing its head and upper "teeth" up. It apparently fed like a largemouth bass, creating suction and pulling things in. But the bass stops with that and eats things whole. Dunks pulled things in and then bit them in half with all time historical superbite. Those blade jaws are scary sweet. In a story I wrote the dragon had a head like Dunks. [Answer] @Ryan\_L makes a very good objection: there's little chance of this "double purpose jaw" evolving. You can start with a human-type jaw. Then, we introduce an environmental change - something happens so that there's a big advantage in being able to swallow something whole. It can be anything, say a fruit. Somehow this fruit pops out for very little time and there's a race to who eats it first. Being able to snatch it in a single mouthful becomes a marked advantage, but now the jaw gets stressed. Subluxation of the temporomandibular joint becomes frequent, and therefore, having an easily-fixed mandible is now advantageous. Very soon in evolutionary terms, the mandible becomes only weakly attached to the cranium, but the masseter muscles develop into a sort of double trapeze: when you bite, first the jaw gets locked securely into place by the longer muscle, then leverage is applied by the shorter, more powerful transversal muscle. Now you can take large bites, and still chew. And it turns out that the fruit you eat doesn't get properly digested from the fruit's point of view (the "fruit" is a bribe the plant "pays" to animals so that they will defecate the seeds far and wide. It's fine tuned to attract, or be more visible to, the most useful animals). Seeds swallowed by our guys are less likely to sprout. Fruits partially eaten by other animals get a better chance. Which means that larger fruits have a selective advantage going for them: they don't get eaten whole, and/or get splattered every which way, seeds included. There's now a selective advantage in having a wider mouth, or a more elastic mandibular joint: you can eat more fruit, of a kind your competitors aren't equipped to snatch away. An "arms race" starts between the plants that grow larger fruit, and our guys who develop larger mouths. After some time (waves hands quickly) the upper jaw also gets modified and can be partially extroflected, but now the oesophagus is stressed and the neck must start enlarging and becoming more flexible. In the end, if everything goes exactly right, you might get something midway between a Great Shark mandible, a snake's jaw and a Xenomorph telescopic dentures. A second set of mobile jaws inside the first, like a snail's radula, can be used to "chew" the captured food so that it can be swallowed more easily. The "eating" would then consist in our guy fully extending its jaws, until they are wider than its now toad-like head, and engulfing the food, remaining in a quite embarrassing and ridiculous position until the inner jaw "walks" the outer jaw to fully enclose the mouthful and start closing on the other side. Meanwhile, the inner jaw is also worrying at the food, scraping away matter that gets ingested. Finally, the mouthful is completely in, the underjaw fully distended, and our guy sports a large bulge under its chin and neck. (This is the point where the jaw can become separated into two horizontal halves). The inner jaw can maybe "rotate" slowly the mouthful to scrape all sides, so that it gets progressively smaller until it can fit in the distended oesophagus and finish its journey in the stomach. [Answer] ## Sharks The jaws of sharks are not firmly affixed to the rest of their skulls, allowing them to come down and forward when striking, opening much wider than you'd expect given the position of the mouth on the sharks' head. To help this, their snouts will also hinge upwards to help get it out of the way. As examples, some comparison photos: Mako, mouth closed: [![Mako, mouth closed](https://i.stack.imgur.com/fwYuF.jpg)](https://i.stack.imgur.com/fwYuF.jpg) Mako, mouth open: [![Mako, mouth open](https://i.stack.imgur.com/COyfi.jpg)](https://i.stack.imgur.com/COyfi.jpg) Great White, mouth closed: [![Great White, mouth closed](https://i.stack.imgur.com/e6cIo.jpg)](https://i.stack.imgur.com/e6cIo.jpg) Great White, mouth open: [![Great White, mouth open](https://i.stack.imgur.com/A9Avw.jpg)](https://i.stack.imgur.com/A9Avw.jpg) And just to show that the filter-feeders get in on the action, too, Whale shark, mouth closed: [![Whale shark, mouth closed](https://i.stack.imgur.com/CkNKL.jpg)](https://i.stack.imgur.com/CkNKL.jpg) Whale shark, mouth open: [![Whale shark, mouth open](https://i.stack.imgur.com/WgBVz.jpg)](https://i.stack.imgur.com/WgBVz.jpg) You wouldn't quite reach snake-like levels of "eating things larger than their head", but 70-80% of it should be doable. [Answer] The jaw could have two configurations. One, in which it's only loosely attached like a snake's, and another where it is firmly fixed like most other animals. Imagine if the joint worked like a with a lock and key. In the loose state, it's like the door is unlocked, you can move it easily. Put the key in and turn it, and the door won't move because the bolt of the lock is in the way. Maybe your animal's jaw is like that; it has an extra joint that it can "lock" to increase how much force it can handle at the cost of range of motion. I think this should be possible, but it comes with some problems. First, the jaw muscles have to be strong enough to "bite off big chunks" like you said. This means they might also be strong enough to break the jaw if something goes wrong with the locking mechanism. Second, there could be a problem with the lock that won't let it open. Many diseases and injuries change the shape of bones. If one happens in the lock, it will seize up. Third, I'm not sure this could evolve naturally. Evolution works in baby steps, but this feature only works when it's complete. What series of minor improvements could turn a normal mouth into this new kind of mouth? Compare it with how eyes evolved to see what I mean. Eyes started as just a patch of cells that could detect light and shadow. Then as this got more precise, they slowly evolved transparent protective coverings. These slowly changed shape to be lenses so the photosensitive cells could now discern images, not just light and dark. While this was happening, creatures also evolved to have more than one, so they could watch a wider field of view, and in the case of predators, they could have depth perception thanks to triangulation. You can see how this is lots of tiny changes, not one big leap. How do you get this new mouth in tiny changes?` [Answer] Having loose yet powerful jaws could be achieved by simply having regular biting jaws, but extremely large relative to the body. This would allow the creature to realistically have a strong biting force, as its jaws are just like real creatures, but with a much larger jaw opening, as the jaws are longer than expected. However, this would require that the creature not have a neck or other such flexibility between the mouth and back of the jaws. There would also need to be cheeks if the length of the jaw is supposed to be hidden, which would limit the jaw's gape. These cheeks would also likely put a limit on the mouth's width as well [Answer] Yes and no In fact some people incorrectly argued that a few dinosaurs could do this. because of some missing pieces they thought the lower jaw of one predatory dinosaur had 5 jaw joints, the main two one and the "chin" and one halfway up each side, that would let the jaws flex open to swallow prey. I tired to find a picture but it is such an outdated idea I could not find the image. They were wrong but there is no reason it could not work provided the joints were stiff hinge joints that did not allow much twisting and you put enough muscle to equalize bite forces. The problem is this has absolutely no reason to evolve. The ability to swallow prey whole is only useful if you CAN'T tear pieces off (or if you hunt underwater). It also has a fairly high cost in weakening the jaw which means you have to invest a lit of resources to make it work and evolution does not favor expensive things that do nothing. ]
[Question] [ I am writing a story, in which I would like to have three locations within about a half hour to an hour driving distance (assuming population, road systems and automobiles on par with the contemporary real world). The location is unspecified; it is Earth-like, but not necessarily Earth. (As long as "Earth-like plants and animals" are plausible, feel free to play with the planet!) * Location A has [sub]tropical vegetation and at least one valley/canyon of moderate size. (Something like southern California, or Hawaii, or your stereotypical jungle/rainforest. Basically, I want to transplant something that closely resembles the San Diego zoo here). It needs to be close to a decent sized urban area, but doesn't need to be especially flat. * Location B is somewhat more temperate and has a mixture of trees (possibly both evergreen and deciduous) and grasses, the latter of which can be due to human activity. It can be a little arid, but closer to the North American East Coast, Midwest or Pacific Northwest is preferred. It needs to be flat enough to support a light to heavy suburban population, as well as several specific locations that are "mostly" flat. (In other words, it isn't San Francisco or the side of a mountain.) Bonus points if the trees change color in autumn. * Location C has a typical annual snowfall of at least 0.3m. Ideally, C and B would be the same place, or at least within about 15-20 minutes of each other. Is it possible for such locations/climates/biomes to exist in such proximity? If so, what major geological or geothermal features and/or differences in elevation would be necessary to achieve this? (Maybe the top and bottom of a mesa? A flat-rimmed caldera, with A in the bottom and B on the rim? Maybe location A has some sort of geothermal heat source?) [Answer] ## The key is coastal mountains, and good roads. Most of the US West Coast has urban areas that never freeze, perhaps 90 minutes from mountains high enough to provide respectable skiing. Another place that comes to mind is Bergen, Norway. For instance last year, the ski slopes an hour out from Sacramento/Roseville announced that skiing would continue into July. I am not kidding. There was a lot of snowpack, and it would last that long. The road from Roseville to Truckee is reasonably well-developed; 55 for trucks and all the cars drive 70. 2-lane roads would have the characteristic of US-50, a bit twisty but not excessively so, with most of the distance being a 60 mph cruise except for hairpins and twisty sections here and there. It really depends on how insane you want to make your geography; your snow scenario requires altitude not jaggedness, so you can have snowy regions with gentle, easy-to-build terrain. The normal happening is that the ocean moderates the temperature of the air to at least 0C and realistically higher; it arrives at the coast saturated with humidity. This temperate air keeps the coastal cities warm. When the air hits the mountains, it must go up; where it is made colder because of the altitude and reduction in atmosphereic pressure. Cold air can't hold as much moisture as warm air, so it must shed the humidity, and down comes snow. Very reliably. [Answer] This makes me think of the Cascades mountains in Oregon and Washington. The mountains are snow-covered but right next to subtropical on the West side because the wind brings weather patterns in off the ocean there. And location C is on the other side of the mountains, on the East side, there are certainly some areas that are temperate if they are close to the mountains, but once you go much more west it gets into desert. [Answer] The Big Island (Hawaii Island) absolutely fits your needs. Mauna Kea (our tallest mountain, actually the worlds tallest mountain-look it up) has snow on it right now,we have temperate-type forests on the slopes, tropical jungle and desert all around. In fact every climate on earth except arctic is represented on this one island. you can drive "essentially" all the way around it in 3 hours (although you would miss a-lot) or cross it and hit say even 5 climate/ecological zones in an hour or two. [Answer] This will work in San Diego itself. Only your location B has to be a flat highland "mesa", so it can be both forested and suitable for sizeable human population. Location "A" we can find next to the ocean, and "C" in the higher mountains, behind "B" location. For general location, you need to stick to low latitudes, and on US West Coast you can't be higher than Southern California if you want to have subtropical forest like "A". ]
[Question] [ The entire Khangates of the Mongolian empire recruited soldiers and resources of conquered states. Of course these soldiers at most times were recruited against their will. Is it the threat of the slaughter of kindred that essentially forces these soldiers into the ruling army? Taking into account, the language barrier, different religious affiliations and obvious cultural differences, will cohesiveness of such an army be possible? If so, how exactly is it done? Kublai Khan's army experienced this problem, with the Chinese and Korean armies amalgamated into his. Perhaps this was the reason for his inability to conquer Japan (other factors too contributed). [Answer] In historical practice this varied widely. It really depends on so much going on in the world at that time, what the societies look like, how big the armies are, etc. Here are just two examples of how this could work in your story: ### To face a larger threat Philip II of Macedon had quire remarkable victory at the Battle of Chaeronea, which wiped out most of the fighting forces of Thebes and Athens. He had basically conquered the main fighting force of the Greek city states, and had he marched through Greece, he undoubtedly would have wiped through the country. However, Philip didn't go to Greece to conquer it - he wanted Greece on his side so (a) he didn't have to worry about them while fighting Persia, and (b) he could use their forces to fight Persia. After this decisive battle, the League of Corinth was set up, effectively unifying all Greece (sans Sparta) under Philip as a hegemony (which, from a military perspective, basically made them a puppet state of Macedon). All the remaining fighting forces of Greece were essentially recruited into the Macedonian army, under Philip's authority. The advantage to the soldiers was: * They won't die fighting Macedon, which would have been the near-guaranteed outcome * Their home city-states can maintain some sense of independence from Macedon (their own taxes, laws, etc) instead of being subjugated entirely. * By helping Philip fight Persia, they can might be able to liberate captured city-states from Persia and help re-instate trade routes * Prevent Persia from conquering Macedon, as Persia was clearly set on conquering everyone and Philip was at least nice enough to give them some independence. The enemy of my enemy is my friend, I guess. * Gain victory and glory by fighting the great evil that is Persia ### To gain wealth or social status Most ancient societies had some type of cast system. Even if it was not strictly defined, movement from rich to poor was difficult if not impossible. The Romans had a weird system where the wealthy were encouraged to be "patrons" (coming from "pater" which means "father") - a type of social father, so to speak - by being generous and giving to the arts, to the poor, etc. But land was held and owned by the wealthy alone. All resource comes from the land. Food, mining, wood, etc. A Roman citizen with little or no land would have no way to gain land by any economic means. It happened, but so very rarely. Land is precious. Land is wealth. Roman soldiers were often promised their base wages (most numbers put this around 225 denarii a year, but it fluctuated), but on successful conquest or retirement they were also promised land - and with that land a lump some of money (as a "veteran benefit" - usually for soldiers were were around 25/30 years). This would give the soldier - and their families - the only realistic path forward out of their social class, and to gain wealth. Now, Rome only allowed Roman citizens to join the army (they even had to pay for their own military gear!), but there were times (eg, Julius Caesar in Gaul) where their army was not big enough. As Julius was stomping around Gaul, invading, conquering, killing, pillaging, there were a few times where he did recruit Gauls to help him fight. A noticeable example was with Vercingetorix, where Caesar used some Gallic troops, promising them a portion of spoils, or land, or whatever to (a) get them to stop annoying him, and (b) put down Vercingetorix. Granted, Caesar often put these troops in vulnerable positions to kill them off, or cheated them on the payout. But think from the perspective of the Gallic troops: they're already conquered, and provoking Caesar means he just kills them all. They've lost a lot of land and resources fighting him, and now they lost the war. If they recruit in and fight for Caesar, then they can move from poor to rich. If they don't, Caesar will eventually take Gaul anyway. Why not help him and get your only chance and moving up in the world? [Answer] From the perspective of an individual soldier in an ancient army, there's really no difference before and after the amalgamation. Regiments will continue to be raised primarily from one part of the empire: say, three from Alicevania, two from Bobtopia, one from Evopolis. If you're a Bobtopian slinger, you serve in a regiment that is almost if not entirely Bobtopian in origin. There may be a few Alicevanians in the general's coterie, but that's none of your business, and it's not something you'll have to deal with on a day-to-day basis. On the battlefield, your officers tell you where to maneuver and who to attack, and (usually) that's the end of it. There's no incoherence on account of cultural, language, religious, or other difference because you're kept separate from each other. Of course, ancient armies tended to be rather draconian and armies in general don't love deserters, but there's no special threat needed to compel you to fight. You fight for the same reason that you always did: because the king or whoever tells you to. The king might be doing so at the behest of another king, or indeed an emperor, but that's not your concern. Your concern is to finish your time and go home with a big bag full of plunder (or a tax exemption, or citizenship for your family, or some other reward). The idea of nationalism and the inalienable sovereignty of the state being important to the common people is far in the future. As for the people whose business this is, well, they have their own reasons for capitulating. Presumably they were either uninterested in fighting the empire or were defeated, and that situation hasn't changed. They will have to cooperate with their new rulers, and there are some logistical hurdles there (languages being an obvious example) - but this is on the scale of a few dozen people. These issues can be sorted out. Note that although this will minimize the impact of differences between parts of your empire, it won't do anything about animosity between them. The British Empire, for instance, had occasional issues when deploying regiments side by side that came from historically opposing groups - like Scots and Irishmen, or Scots and English, or Scots and other Scots. Commanders would have to consider the temperaments of the individual units and how they were likely to interact when deciding on an order of battle. [Answer] > > Is it the threat of the slaughter of kindred that essentially forces these soldiers into the ruling army? > > > That's a possible reason, but the overriding one is that they are soldiers, no work, no pay, they'll starve to death. So either they just work for a new employer who has been proven to be successful and might make them wealthy, or they run away and grub around in the dirt trying to make a living in constant danger of being killed. > > Of course these soldiers at most times were recruited against their will. > > > Quite often these soldiers were recruited against their will by their own leaders as well, the lower ranks anyway. [Answer] The soliders might not have any concept of nation, or who the boss of the boss of the boss of the village headman is. Look at European history -- often the court of the king spoke a different language than the peasantry. There is religion, and there is a social order, and the potential soldiers are at the bottom of the order and people on top tell them what to do. The development of a nation (and of a flag larger numbers of people would fight and die for) came much later. ]
[Question] [ This is a submission for the [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798]) Recently I had a vision of a colossal underwater bird-like figure. I would describe it as follows: * Roughly the wingspan of the length of a blue whale * Snow-white * Typical shape and feathering of a bird of prey (I may have mistaken something else for feathers) * Gliding into the depth, probably in the [mesopelagic/twilight zone](https://en.wikipedia.org/wiki/Mesopelagic_zone) Since such a creature couldn't possibly be an actual bird, unlike [the aqua-bird](https://worldbuilding.stackexchange.com/q/51661/59407), what is my giant mid-sea bird? [Answer] Let's start with something in the Real World (TM), then try to see whether we can manipulate its future evolution into your creature. The thing I have in mind is the humble [gannet](https://en.wikipedia.org/wiki/Gannet), birds of the Morus genus. As seen in this article at [Media Drum World](https://mediadrumworld.com/2017/02/02/4361/), when these birds feed, they spend quite a bit of time swimming to a bit of depth, and do so quite adeptly. [![enter image description here](https://i.stack.imgur.com/0B40W.png)](https://i.stack.imgur.com/0B40W.png) We begin with two-out-of-four of your features already in place: Snow-white, and typical shape and feathering of a bird of prey. We just need to figure out how to grow it much, much larger, and get it to abandon its life in the skies and greatly increase its diving depth. How? The usual evolutionary pressures: eat, don't get eaten, make more of your kind (i.e. sex). As the fish dive deeper to escape, the mega-gannet must follow. But now the sharks, which already compete with the gannet at the bait ball, have a better chance to pick them off along side the fish. Time to get larger, too large for a shark to swallow. This will eventually make it too large to fly. Alongside this, the mega-gannet will probably become swifter at swimming. I'm uncertain whether the mega-gannet might develop a blubber layer, or if feathers can adapt to provide cold-water protection (penguins, for example, have both). Finally, those mega-gannet which are most successful at eating and not getting eaten will also be more successful at breeding, and these traits will augment in each generation. Given the right circumstances and a few million years, anything can happen. [Answer] It's for sure the notorious Pinguinus Humongous. It's a descendant from penguins, which, instead of feeding on small fishes, decided to go big and hunt for dolphins and other large sea mammals. Its size is necessary for hunting those preys, and the feathers come from its ancestors being birds adapted to the sea environment. [Answer] Giant nudibranch. [![nudibranch](https://i.stack.imgur.com/u9zXs.jpg)](https://i.stack.imgur.com/u9zXs.jpg) [source](https://rushkult.com/eng/scubamagazine/nudibranchs/?utm_referrer=https%3A%2F%2Fwww.google.com%2Furl%3Fsa%3Di%26rct%3Dj%26q%3D%26esrc%3Ds%26source%3Dimages%26cd%3D%26ved%3D2ahUKEwjK4bi9-6XhAhXKdd8KHU0bAWQQjxx6BAgBEAI%26url%3Dhttps%253A%252F%252Frushkult.com%252Feng%252Fscubamagazine%252Fnudibranchs%252F%26psig%3DAOvVaw3ZRuvQCQ7tV_8eS2UYgyOq%26ust%3D1553901126929133) These are ocean animals. They swim slowly along as I imagine your creature might. They can have a vaguely avian outline as seen here. Known nudibranchs of course do not get to the size you want, but maybe they could. The molluscan body plan can scale up. Squids get big. [Answer] Except for the feathers, your creature is rather like a manta ray: <https://en.wikipedia.org/wiki/Manta_ray> So convergent evolution is your friend here. Just as the demands of hydrodynamics cause sharks, tuna, dolphins, and ichthyosaurs to all look much the same to a casual eye, your mesopelagic bird is descended from penguins that evolved into occupying the same environmental niche as manta. [Answer] It's a giant ray. > > Roughly the wingspan of the length of a blue whale > > > Rays can be big. The giant oceanic manta ray has a 7 metre wingspan, and with sufficient food availability they could evolve to be very big. Perhaps they could crystallize their cartilage skeletons with some harder mineral like calcium phosphate, calcium carbonate, or chitin, for better support. > > Snow-white > > > You could have seen an albino/leucistic individual. Or maybe it's so big that it fears no predators, and thus needs no camouflaging pigmentation, remaining plain white. If it spends much of its time in the deep, it wouldn't have much use for coloration anyway. > > Typical shape and feathering of a bird of prey > > > What with their huge wings, rays certainly can have a wholly avian profile from above. As for the feathers, perhaps take inspiration from the yeti crab? [![enter image description here](https://i.stack.imgur.com/0IkcH.jpg)](https://i.stack.imgur.com/0IkcH.jpg) The ray's dermal denticles are long and filamentous, and amongst these filaments it grows bacterial cultures which it then eats, perhaps by means of some long fin-sweeping proboscis. > > Gliding into the depth, probably in the mesopelagic/twilight zone > > > The depth doesn't really matter, most large whales change zone every now and then, with some of them diving well below the twilight zone despite living in the sunny layers. ]
[Question] [ Closed. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it can be answered with facts and citations by [editing this post](/posts/64506/edit). Closed 7 years ago. [Improve this question](/posts/64506/edit) There's nothing good on TV so you've decided to take over the world. The good news: you can have complete telepathic control over a whole species\* of animals! That should be useful. Here's what you can do: when you start using the power all the animals of the species go to "waiting for commands" mode\. Doing what you say is on them, so you can give them any task \that they can comprehend\\. (I.e. you can't tell a fly to solve a puzzle, you'd have to tell it where to turn each time. You could tell a bee to make honey) this includes "act normal". When you provide instructions, selecting who this applies to is on you. So you can say "every third male animal which is in Africa or over a source of water do X) As long as you know what you want. What you want: world domination!. It doesn't have to be formal, as in being the supreme president (?) and have boring government meetings. The key word here is power. You should be able to do whatever you want and have people obey you. don't assume this will be easy. People may fight back if they see fit. It's not necessarily about making the strongest army and finding animals capable of destroying the world, because a) you don't want to destroy the world and b) that might piss people off, and if they kill you, well, that's not good. People won't necessarily know what you can do (you can tell them) but keep in mind that you want power, and for that people need to treat you a certain way (or do they?) What's the best plan you can find? --- \The definition of a species is pretty arbitrary. Just go with anything that most people would agree are the same animal. \\this is why you can't use humans. You will also go to waiting mode (as you're a human) and no commands will ever come --- ## Edit: The question isn't* which species is able to make the most damage. I was looking for something a little more elaborate. You want to have control and to have people do what you say. If you try to ruin the world people would try to stop you, if they know it's you, or just ignore you if the don't. [Answer] # TLDR; Bees Update because of Edit: There seems to be a lot of confusion about this being able to destroy the world. Although YES it is possible, keep in mind other methods of gaining power through this. Most of the power in this world comes from money, and if you can control bees, think of being the most successful farmer in the world, and create a legitimate business on it. The ease of ~~decimating your competition~~ raising your bottom line due to them lacking easy pollination methods would allow you to just make your business "a bit" better. You might be hated, but not any more than any other business person, especially if they can't discover why their crops sporadically fail. "Oh no, your 3rd field failed? Sorry to hear that.....Would you like to purchase from me instead? I have plenty!" [![enter image description here](https://i.stack.imgur.com/pl1BK.jpg)](https://i.stack.imgur.com/pl1BK.jpg) Ever seen the Bee Movie? Bee's are one of Earth's most important animals, and the removal of them from any ecosystem would cause catastrophe not only across the plant kingdom, but the animal kingdom as well (herbivores need food!). Modern agriculture and more than a few industries rely on the byproducts or capabilities of bees. Just think of beeswax, honey, pollination, etc. [Source 1](http://www.onegreenplanet.org/animalsandnature/why-bees-are-important-to-our-planet/) [Source 2](http://www.bbc.co.uk/guides/zg4dwmn) [Source 3](http://www.bbka.org.uk/kids/importance_of_bees) [Source 4](http://greendustriesblog.com/greendustries/2012/04/12/bees-and-survival-of-the-human-race/) > > Bees are some of the hardest working creatures on the planet, and because of their laborious work ethic, we owe many thanks to this amazing yet often under appreciated insect. > > > Our lives – and the world as a whole – would be a much different place if bees didn’t exist. To illustrate this fact, consider these numbers: bees are responsible for pollinating about one-sixth of the flowering plant species worldwide and approximately 400 different agricultural types of plant. > > > In short, without the polination capabilities of bees, agriculture would suffer greatly. This would give you unrivaled control over the general populace, as you now control the food supply. This method has the added bonus of making you essentially the Supreme President of Earth, so long as you're not immediately apprehended by authorities. To prevent any sort of assassination (if you're going the world owning method) would be to create a [dead man's switch](https://en.wikipedia.org/wiki/Dead_man%27s_switch). Do you dare to touch the one who can kill you slowly as you die of scurvy? Let's be honest though, who doesn't want an utter swarm of bees at their beck and call? Gives a new meaning to the term [black and yellow](https://www.youtube.com/watch?v=UePtoxDhJSw) doesn't it? Especially those [GIANT black bees](https://en.wikipedia.org/wiki/Megachile_pluto).... [Answer] For real power, I would choose cockroaches. They are hard to kill, there are lots of them, and you can use an army of them to slowly rise to power over the world. Imagine if every gun aimed at you didn't work because a roach was in the clip instead of a bullet. Imagine if anyone who talked out against you was swarmed with roaches. Imagine if your followers never had to deal with cockroach infestations (but everyone else did). You could play it "evil guy who controls cockroaches" way or you could play it "Savior of Humanity from the cockroaches" way, but either way you win. For symbolism/cool factor: Dogs (assuming it also carried over into wolves for coolnesss). Man's best friend? No, more like THIS man's best friend. [Answer] ## [Mosquitoes](https://en.wikipedia.org/wiki/Mosquito) --- [Mosquitoes are the most deadly animal on the planet](http://adventure.howstuffworks.com/dangerous-animals1.htm) they also exist on every continent except Antarctica. (Also there are [no mosquitoes in Iceland and a few other small places](http://www.theatlantic.com/international/archive/2011/04/where-move-if-you-never-want-see-mosquito-again/349934/) lucky them.) So they exist basically everywhere they can be used to carry plagues to people you don't like and torture others. Can humans stop my mosquito army? The short answer is no here are my reasons: A) We are currently trying to eliminate certain mosquito populations already and have yet to be successful. B) You will have control of you're mosquitoes and you can outsmart our newest method of killing mosquitoes that mostly [rely on breading behaviors](http://www.npr.org/sections/health-shots/2016/12/14/504732533/to-fight-malaria-scientists-try-genetic-engineering-to-wipe-out-mosquitoes). C) [Female mosquitoes can lay 300 eggs at a time](https://www.megacatch.com/mosquito-faqs/mosquito-facts/). Their average lifespan is already about [2 months](https://www.megacatch.com/mosquito-faqs/mosquito-facts/) if several mosquitoes are eliminated they have probably already birthed the next generation of mosquitoes so no biggy. D) Actually [eliminating mosquitoes would destroy earths ecosystem](http://io9.gizmodo.com/what-if-every-mosquito-on-earth-went-extinct-tomorrow-1646840383). The only problem is they will die [or hibernate](http://www.ct.gov/mosquito/cwp/view.asp?a=3486&q=415106) in harsh cold conditions so you will only have control over people in tropical climates or during the summer. This can be overcome by invading peoples houses during the winter, or finding any buildings they can stay in that will keep them warm. Mosquito repellent and/or deet is not a problem because this only works on mosquitoes because they don't like the smell. Using mind control you can force them to like the smell and they will continue to attack humans. Another thing to note is that only female mosquitoes "bite" humans this should be no problem though because mosquitoes approximately outnumber humans 10 to 1 so you should have 5 mosquitoes ([sex ratio is 1:1](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577382/)) per person around the world at any given time. Simply telling mosquitoes to only feed on humans would cause global distress. [Answer] Norway Rats are a good choice they live everywhere humans do, there are trillions of them, and they can chew through concrete. plus most of our ways of killing them rely on behaviors a army of controlled rats might not have (food seeking). depending on how good your control it they are large enough to operate many machines as well. Consider how many house fires are caused by rats chewing through electrical lines, now imagine them all doing it at once, especially after opening all the gas lines. Although I should mention squirrels are [well documented](https://en.wikipedia.org/wiki/Squirrel_Girl) as the perfect creature for defeating supervillains. [Answer] A traditional army made up of animals isn't going to be of much use...Humanity is far too far advanced on a military level to really be threatened by any single species at this level. For this to be effective, you need to hit the environment or our food chain. Plankton! Borderline answer, as they are technically plants...but these little creatures are the bottom of the food pyramid and produce a large portion of our environments oxygen. Someone telling the Plankton to kill each other on sight would collapse the oceans biosphere very quickly and take a dent out of the oxygen supplies available on earth, who knows what effects a complete plankton die off would have, but I guarentee you that with this power, you'd hold the earths biosphere hostage. Chickens! Best count I can find online is around 49 billion chickens per year are consumed on this planet. Enraging the chicken stocks (ya, food source suicide is seeming like a likely route for you) and having them slaughter each other will have a few effects...a hurting food supply chain being a minor worry to the amount of chicken corpses that would need to be disposed of (or face harsh health risks). Maybe the chickens were willing and able to take down pigs or cows while they are at it, ya might as well collapse the entire farming industry here. Rats! They've spread plague accidentally in the past...if this can be turned into a coordinated effort to give rabies and whatever other disease they carry to humans, their pets, and their food sources...these rats could be very destructive. Imagine entire herds of cattle needing to be put down because rats had given them all rabies. They could also chew through vast amounts of wiring, use their numbers/breeding rates to overwhelm power stations with their own dead bodies, climb into motors and plug exhaust pipes...assuming these rats didn't care about their own mortality, they could be extremely effective with bringing our society to it's knees. I'm pretty sure they could end the internet if they knew what they were doing...that'd be a hostage point and a half...obey me or I kill the internet! [Answer] It's hard to choose one species, but here are some good starting points. While any individual species may not be able to do harm, consider withholding an important one - and using it to blackmail world leaders into getting what you want. ## Livestock Preventing livestock from eating food will be much more effective than having them physically attack each other or people - although they are numerous. Chickens, pigs, cows - even horses may suffice. You can ruin economies and starve populations if you play your cards right. ## Disease Carriers While a logistical nightmare, you could consider using rats, birds, and other disease-carrying animals. If you have the ability to affect a large amount of people, surely you can hold them for ransom. ]
[Question] [ A common thing we see in zombie movies in the ability to remove the infected area (usually the arm or leg) despite the fact that a blood borne illness would travel throughout the body. How could I design a zombie illness that would allow for removal of a limb to save the person? For example, would a virus be better, or would a fungal infection allow for limb removal? Would blood borne biting work or would water borne infection be better? What zombie design would allow me to remove a limb to save the person? [Answer] Use [rabies](https://en.wikipedia.org/wiki/Rabies#Cause) as your model. Once biten, the virus must replicate and move towards a nerve cell. Once a nerve is infected, it travels its way up the nervous system to the brain. Up until this point, it is treatable. It takes about 10 days. Radiolab covers the mechanism in [Rodney Versus Death](http://www.radiolab.org/story/rodney-versus-death/). [Answer] Most germs (virus, bacteria or fungal) are harmless in small amount. They need to overwhelm the immune system. So, even if a few germs invade the body through the blood, the bulk of the infection will be localized around the bite... at least for a time. This means you don't need anything special. Infection works pretty much like in the movies. If you cut the limb quickly, you're safe. [Answer] Take a look at necrotizing fasciitis. The infection progresses quickly (think hours) and decays the flesh like gangrene. It's spread through contact with open wounds and the treatment is antibiotics and/or amputation. Necrotizing fasciitis doesn't typically affect healthy people, however, a mutated form with increased antibiotic resistance would be dangerous to healthy people especially if introduced directly into the bloodstream through a bite for example. Mucormycosis (a fungus) is also pretty cool for the purpose of zombie scenarios, because it affects the brain and skull and can be spread after natural disasters. Amputation of affected areas or removal of the brain is a potential treatment as well. What would be cool - well not cool - but there are some bacteria right now that have the ability to pass their antibiotic resistant genes onto other microorganisms that aren't even in their same family, kind of like a bacterium giving another bacterium an infection. Except, that infection actually helps the other bacteria become stronger. Maybe a MRSA strain gives its resistance to Mucormycosis, and kind of symbiotically hitches a ride on the spores. Then, a series of hurricanes/tornadoes/floods creates a perfect breeding ground for the two microorganisms. As in the answer above, healthy people are usually able to fight off infections, however, susceptible people could be initially infected from the natural disaster fallout. Because the bacteria/fungus duo is super-resistant and less lethal, it spreads quickly as infected peoples' slowly-decaying brains cause them to lash out violently, creating cuts/wounds in others. After the initial natural-disaster-caused infection of susceptible populations, most of the transmission would be from zombie to human, instead of from mud/dirt to human. I think you'd have to reconcile that the disease wouldn't make the zombies immortal, fast, or super strong. Also, the disease could be spread through infected dirt as well as from a bite. ]
[Question] [ You find yourself on a world with no gunpowder...don't ask why...or how you know that there is no gunpowder there just isn't any available to you, nor are alternative propellant options available (work with me here). You are preparing to defend an otherwise modern era (there are obviously some other differences...) city from an invading horde of savage aliens. You are vastly out numbered and looking to create weapons that can mow down the legions preparing to attack you. * The weapon must have a fire rate equivalent to the .50 cal mounted machine gun. * At least 80% of the power of its traditional counterpart. What methods are available for creating a powerful rapid fire weapon? [Answer] You have a few remaining options. Air, electricity, and alternative explosives. Pneumatic Gun A [pneumatic weapon](https://en.wikipedia.org/wiki/Pneumatic_weapon) uses compressed air or steam to accelerate a projectile. There are rapid firing potato versions, so I don't think you'd have trouble making one that fires bullets instead of spuds. However, the power will be difficult to get up to gunpowder replacement levels. Steam will be easier to use than compressed air, but may not be as easy to store. Gauss Gun A [gauss gun](https://en.wikipedia.org/wiki/Coilgun) works by triggering successive electromagnets to pull a projectile along the barrel. You can actually get a higher energy output than a gunpowder weapon, but the repeat rate may be lower if the power output of the generator is not high enough to recharge the capacitors quickly enough. However, you could simply use many interchangeable capacitors banks or a massive generator. Railgun A [railgun](https://en.wikipedia.org/wiki/Railgun) is similar to a gauss gun except the projectile is part of the circuit for generating the electromagnetic force. This reduces timing complexities but increases the required precision of the gun and projectiles. As with the gauss gun, higher power output than gunpowder is possible and it will require significant energy storage to fire rapidly. Alternate Explosives There are [a lot of explosives](https://en.wikipedia.org/wiki/Explosive_material) other than gunpowder. You can use lots of different types of high-explosives to launch projectiles. Presumably, you don't want this though, so I won't expand much. --- EDIT: Centrifugal Gun As for your question on using centrifugal force. With that clever naming gun people are known for, there is the [centrifugal gun](https://en.wikipedia.org/wiki/Centrifugal_gun). It can be hand-cranked or powered by compressed air/steam. [![enter image description here](https://i.stack.imgur.com/mDXlR.jpg)](https://i.stack.imgur.com/mDXlR.jpg) It has been tested several times in the US and billed as the "silent machine gun" but has always been abandoned due to extremely poor accuracy. This makes sense, with centrifugal force the projectile can't be accelerated while it's being guided down a barrel pointed at the target. Either the power is reduced while sliding down a barrel or the accuracy is all in the milliseconds that the projectile is released from the spinning accelerator. There is [a patent on a centrifugal gun](http://www.google.com/patents/US6520169) from 2003 called DREAD which claims to launch projectiles with the speed of a handgun (300 m/s). [Answer] Converted Vehicle Engines Vehicle engines achieve very high rotational speeds, and it should be possible for an engineer to re-work an engine so that speed gets transferred to projectiles at a high rate of fire. I don't know exactly how you'd do this - I'm not an engineer! - but it seems like it should be possible. As a reference, unless I messed up my math the energy it takes to accelerate a one-ton vehicle to 60 mph is roughly the same as the energy to accelerate around a thousand bullets to 1,000 m/s, which is about what a .50 cal fires at. So the energy is there to have a high rate of fire, you just need to figure out how to transfer it. This has some downsides that would keep it from being something we'd use: 1. You need to carry around a heavy engine, and move that engine to aim. Your "guns" are going to weigh several hundred pounds, and they need a gas tank. 2. I'm guessing it's pretty inefficient, energy wise. 3. It might be inaccurate compared to our weapons. 4. The failure rate will probably be higher than we'd be comfortable with, especially with a converted device. But when you don't have gunpowder at all, and you're presumably defending a city so fixed installations are workable... The major advantage, of course, is that you probably have a ton of vehicles currently available. And it's going to be a lot easier for you to convert existing engines into weapons, than to build a ton of new guns from scratch. [Answer] All weapons come down to the transfer of energy. Samuel's answer listed several, all of which are based on a projectile as the energy transfer mechanism. Of those, a gauss or railgun are the most appropriate, especially since you did not mention any other limitations on technology. Instead of a chemical propellent based charge, each round could consist of a charged capacitor and a projectile in a specially designed case. A magazine would be capable of holding a number of these rounds, providing you with an analogue for the current chemical propellant based firearms we use in the real universe. An alternative could be using radiation as the energy transfer mechanism - lasers or masers exist now that are capable of taking out enemy aircraft and missiles. In our universe fire-rate is an issue, however I am certain that in a world without chemical propellant, (and I therefore assume without chemical propulsion such as the internal combustion engine) the technology around electrical power storage and delivery would be more advanced. [Answer] Since most potential energy sources are either very limited and much lower power than the chemical energy stored in gunpowder or would require massive infrastructure (electrical energy weapons like coil guns or railguns, the best solution would not be to rely on rapid fire or kinetic energy, but on creating explosive or flame warheads. A small crossbow with the equivalent of a hand grenade strapped on the quarrel will do a lot more damage than a crossbow bolt on its own. A trebuchet or ballista can hurl warheads the size of buckets to large drums, increasing the size and effect of the warhead. Since the stipulation is no gunpowder, the explosive effect could be through the release of a flammable dust on impact (this can be simulated using coffee whitener powder, or in industrial settings with coal or flour dust suspended in the air). If ignited by an on board fuse or a following shower of flaming arrows, the explosion is a "heaving" fuel air explosion, which can crush bunkers and fortifications, or even damage tanks and armoured vehicles, so the horde of aliens are vulnerable unless they are using even higher technologies like suborbital vehicles and force fields. [Answer] Clean energy power is all i can think of. Wind, Solar, some way for water propulsion etc.. You also have spring and tension forces as well such as catapults and bow and arrows. Maybe some sort of electric battery as well similar to blasters in star wars and star trek. I don't know if your going to be able to achieve 80% power of a .50 cal without a more "violent" reactive substance. You would need tornado powered wind forces to get close. ]
[Question] [ In science fiction technology that induces a gravitational pull is often sidelined as just a convenient way of getting people to walk on a spacecraft. The implications of gravity that can be turned on and off are actually much bigger than that. Theoretically you could help launch ships into space by using a satellite equipped with an artificial gravity generator to lighten the gravitational pull in an area. This could allow to save a considerable amount of fuel or in this case launch monstrously large ships into space. Spacecrafts the size of multiple football fields could be constructed on earth, without the need to send rockets back and forth into space to assemble pieces bit by bit. On paper this all sounds fantastic, but realistically it would be much trickier than that. The handwavium generator is a theoretical device that can generate varying magnitudes of gravitational force. You could set it to moon gravity (1.625 m/s2 about 0.166 ɡ) or earth gravity (9,807 m/s² exactly 1g) at the flick of a switch. The device can generate gravity on par with a planet but doesn't have the same radius, so naturally the area of effect is smaller. Obviously I don't want to set it in orbit to 1g to cancel out gravity completely, or worse have it come crashing into earth. It would have to be half or less than 1g to not cause unwanted destruction on the surface. The predicted effects would be a localised expansion of the atmosphere, a drop in sea levels and of course everything would seem lighter. The idea is that the artificial gravity field dips just on the earths surface on the linear center, to affect only the region that needs to be lightened. What would permit such a system to work? Are there any unforeseen consequences? Edit: This isn’t a reality check. “Gravity a interacts with gravity b, can this be used?” is what is being asked. Obviously creating gravity is fiction. Please review your answers. [Answer] G-crane You won't have to put the generator in orbit permanently, but you'll want to avoid operating this generator on the planet surface ! Because of the short distance, it will have a devastating effect on surrounding matter. Pull your space ship up (G+), rather than pushing it (G-). To prepare for lifting a ship into orbit, your handwavium generator could first lift itself, e.g. 50m above the ship's ceiling. Then move the ship under it. When the G-crane is switched on, it will pull anything off the surface, that resides in its vicinity. Not only the ship. The ship will need some armour, because the weight of the matter will put pressure. The trick to minimize taking matter along: while the cargo accelerates upward, the generator should move up, along with it. While the generator elevates the space ship "hanging" under it, its influence on the planet surface will rapidly diminish (G force diminishes with square of altitude) The first few minutes of the lifting process will cause near objects, sand, dust, water and atmosphere near the surface to move upward as well. The lifting will cause large amounts of matter to stick on the bottom of the ship. The force should be maintained, until the ship is far enough up in space, to prevent sticking matter from falling back too early. When the generator is switched off and your ship is in orbit, the material sticking to the ship will detach and burn up in the atmosphere. It is still advisable to move the whole operation into flat, uninhabited territory like a salt lake. The initial move will cause a crater. Underways, a spontaneous low pressure area is formed under the ship. Strong local airflow could cause tornados to occur.. maybe other weather effects.. [![Explanation lift limiting G-force range of generator](https://i.stack.imgur.com/h5xpm.png)](https://i.stack.imgur.com/h5xpm.png) [Answer] > > What would permit such a system to work? > > > Magic, plain and simple. What you're asking for is so far away from any plausible scientific or engineering feat there's not really any other answer. Even in scifi, the antigravity fields tend to be confined to very small volumes, so this is even more unsound than star trek or star wars. > > Are there any unforeseen consequences? > > > Your plan is almost entirely made of unforseen consequences. Consequence the first, for example: once the gravity beneath your satellite is neutralised, what keeps your satellite in its orbit? Without gravity, it'll shoot off on a tangent away from Earth at orbital velocity until the gravity-neutralizing effect stops working. A very powerful rocket would be needed for station keeping. Speaking of station keeping, you'll need to have the area of effect more-or-less centred on the thing you're lifting all the way up. This means sticking your lifting satellite in geosync orbit, or having it in a forced orbit at low altitude (requiring very powerful rockets) or on some kind of [dynamic orbital ring](https://en.wikipedia.org/wiki/Orbital_ring). There will be some interesting atmospheric disruption along the zone that the antigravity system affects. I'm not entirely certain what this will look like... there will be a general upward movement as the stuff at the top escapes into space and the high pressure stuff further down tries to equalise with the lower pressure stuff above it and air will be sucked in from the surroundings at lower level and blown out at higher levels, possibly forming some kind of large toroidal vortex that might actually form a tornado. It'll also be subject to interesting coriolis effects if you're not pointing an antigravity beam along the Earth's axis of rotation, but this isn't a large effect (see [this answer of mine](https://worldbuilding.stackexchange.com/a/198332/62341) for some discussion of coriolis effects for things suddenly not subject to gravity). What happens to the ground (or ocean) in the volume of effect is probably a bit more dramatic and destructive. I think the ocean will fountain up, pushed by pressure from below with substantially more force than the air, because there's potentially a lot more ocean pushing down and providing pressure from below. I haven't the faintest idea if the tensile strength of the crust and upper mantle, and the viscosity of the mantle in general is enough to prevent the formation of a giant magma fountain but, y'know, it might not be. --- The biggest issue is the whole "conservation of energy" thing. If you can just conjure energy from nowhere by lifting stuff up magically for free, then turning the gravity back on, then you've broken huge amounts of physics, and I can't help you. Clearly, if you can create free energy then merely using this thing for spacelaunch and keeping your spacecraft comfy seems a bit silly... you should be blasting yourself up the Kardashev scale. (speaking of breaking physics, what happens if you use one of these things on a black hole? can you now cross back through an event horizon without waiting for the black hole to evaporate?) If you can't create free energy, then you'll have to pay for every single joule of gravitational potential energy you're imbuing the material you're lifting... this would be about 3.4 MJ/kg for lifting something from the surface to the altitude of the ISS. Obviously lifting any useful amount of mass requires a large amount of energy, and the mass of a column with cross-sectional area 1m2 reaching all the way down to the Earth's core would be gigantic and need such a powerful energy source as to effectively be unfeasible. Clearly you need some kind of additional constraints on your AG system... it nullifies gravity between two plates, perhaps. Then you can stick one of the plates in orbit and one on the ground, and only have to lift the atmosphere (10 tonnes per square metre at the surface) plus the weight of your spacecraft. If you were clever, you could build a dynamically suspended tube (maybe using a [space fountain](https://en.wikipedia.org/wiki/Space_fountain), or maybe the antigravity system could do this trick too) so as to prevent lateral air movement during operation, preventing the formation of a tornado. Suddenly though, if you can make a confined gravity nullification system then maybe you can simply make a box that renders its contents effectively massless (though you might wanna consider how inertia works when moving something confined in this way, because I'm not gonna touch that problem here) and just attach that to a regular spacelaunch system. Sure, you can't lift football-field sized things into orbit, but on the other hand you can do all sorts of other neat things that don't break the local atmosphere or crust. You have now more or less re-invented cavorite, or as was pointed out by DWKraus, the spindizzy, or any number of their descendents. [Answer] It is astonishing how much we know about gravity, and at the same time not know what it really is. We can see it is an observation of a warping of spacetime inwards towards regions of higher mass. We can calculate its effect on objects in terms of movement and time. That's about all we know. We don't actually know how it works, or how gravity (General Relativity) relates to the Standard Model. Many posit that if we can find this link, a theory of Quantum Gravity, it may yet yield developments that could result in our ability to manipulate it. In your scenario, this is sidestepped, but this link would inform the consequences of your system. There are several predominant theories currently being studied that attempts to reconcile it, such as Loop Quantum Gravity or String Theory, but no current experiments can fully confirm or rule them out - or even if they are on the right track. So for your launch assist system to work: * You may need to develop a tested theory of Quantum Gravity, to enable your satellites to be designed to manipulate regions of space using this theory * You would need to understand how to alter SpaceTime, and what 'time and space' is (properties of our universe currently in dispute), to enable velocities and masses to be controlled, and a way to control it. * Apart from the theory, your satellites need also to be practical. They presumably need energy to do this, and the energy required may need to be colossal. * How it affects the surrounding gravitational fields (or how it bends SpaceTime) and affects Earths own SpaceTime bending is unknown, as we don't have a working theory. Such effects are not observed in nature, and it is not known if bending away from dense regions is even contemplatable. There may be yet a physical limitation of our universe that prevents anti-gravity - we just don't know. [Answer] * Perturbs the orbits of every other satellite badly. Gravity has the longest range of any fundamental force. Even making the satellites point gravitating masses only subtracts off the radius of the Earth from their effective range, given that 1 g is the nominal gravitational acceleration at the surface of the Earth. * Perturbs the orbit of the Moon itself. 1 g is straight-up acceleration, not thrust, and therefore is not proportional to mass. It is proportional to distance and these satellites are passing closer to the Moon than the Earth so you have the [n-body problem](https://en.wikipedia.org/wiki/N-body_problem) to solve. * Probably screws up weather patterns and tides beneath it pretty good, with global effects. * Increases [atmospheric escape](https://en.wikipedia.org/wiki/Atmospheric_escape) to space quite a bit * While it does null gravity in a zone between the satellites and Earth, then you have to fight the gravity of both the satellites and the Earth once you try to reach an orbit above them. [TANSTAAFL](https://en.wikipedia.org/wiki/There_ain%27t_no_such_thing_as_a_free_lunch). [Answer] The system you propose is fiction and has nothing to do with scientific fact. There is nothing wrong with that if you are writing a work of fiction, but remember it is a fiction. If such an anti gravity device were to become possible it would enable perpetual motion as water (for example) could be drawn up when the device was switched on and then allowed to fall through a turbine when the device was switched off. But this is just one example problem the whole idea of an anti gravity device would drive a coach and horses through the entirety of modern physics. [Answer] In order to not be a perpetual motion machine, the device consumes power based on how much work it needs to do. So, for people walking around on a deck, you just need a small amount of buffering to handle short term variations in various objects rising and falling a small amount, but at the end of the day it tends to cancel out. But for launching something, using a tractor or repeller beam, it requires as much energy as the change in potential energy you are effecting. To lift a ship and let it get away, you must supply as much power as you would with any normal means of lifting the ship. Now, on the deck situation we assumed that it works in reverse, that falling objects in the field can give energy back to it, at least if it's re-used quickly. For a busy space port, they have as many incoming ships as departing ships, and can make use of the same principle on a larger scale. Traffic control tries to balance it out so that breaking the falling ships transfers power to the departing ships. # a field between two plates My own idea for ship-based gravity that avoids the issues of messing up satellites etc. and has some other advantages is that the artificial gravity requires two plates, and produces a uniform field between them. This is analogous to the electric field between two charged plates. People on the deck will feel a constant gravity, but nothing happens beyond the bounding plates. For launching something, you let it accelerate to the "bottom" plate and then escape, by opening a hole in that spot. Again, it's analogous to using an electric field, and it requires power to accelerate the object. [Answer] My enjoyment of stories involving artificial gravity on a space craft has always assumed that it was not actually gravity of some kind (maybe it's tricks of inertia, force fields, etc), exactly for the reason you propose. The ability to create actual gravity fields would have far reaching effects, and some of them devastatingly dangerous. We first need to discuss how real gravity works. Gravity is a natural property of all matter. All matter attracts to all other matter. The weird part is that it's an extremely weak force, except as more matter clumps together, the gravitational force increases. More massive objects exert more gravitational force than less massive objects. It's even weirder that gravitational force between two objects increases as the distance decreases. Two objects approaching each other propelled only by their gravity will accelerate as they get closer together. This is why gravity is expressed in distance per time squared. It's not necessary to go into the exact math (mostly because I don't understand it, lol), but it's necessary to know that gravity is based on mass, is stronger with more mass, and is exponentially stronger with linear decreases in distance between two objects. For true artificial gravity, there's really only one conception: an exact point in space that, with respect to gravity, imitates the center of mass of an object. In the plainest understanding, the machine targets a point in space that then attracts all other matter to that point with an actual gravity field. Where it gets tricky (meaning, using such tech effectively), is that gravity is mathematically tied to the mass of the object. If you wanted to lift by gravity with the same force as earth's gravity, then you'd need a massive point that matches earth. But suddenly dropping an earth weighted point in the solar system would have obvious devastating effects. In fact, it would be so bad that the only use for that would be to destroy planetary environments. Where it might be an actually usable technology is if it's possible that a mass can be big enough that when in close proximity it would attract nearby objects at greater than planetary gravity, but would not be massive enough that it would meaningfully affect the planet itself. To make this truly useful, this technology would have to be able to move the artificial gravity point so as to keep a consistent pull on the target object. So I imagine a massive point, with virtually no volume, that you can place in extremely close proximity to an object, and as that point pulls the object, you move the point in your desired direction. Depending on your readers, maybe you can hand-wave this as possible. To actually find out, you'd really have to ask a physicist. My lay-understanding has me believing that the math would punch out unfavorably. It would be intensive pull at only a few millimeters, and virtually none at only a few centimeters. If we put such a force above your head, it'd be more likely to make you dizzy before actually lifting you in the air. So anything you lift would need a specially designed harness. The harness has a bit of mass which is the target, and when it moves, it pulls by attachments your actual target object. You couldn't just grab whatever you want. Every "gravity move" would require planning and preparation. Lifting an Earth built space station would require a very small mass, like a golf ball, that could attach to and then lift the entire station. Sounds unlikely, so you'd have to add like a thousand golf balls all over and inside the station, and then target them all in unison. Holy crap, this is getting complicated! But if it's possible, then all the terrible side effects go away. That's great! Another interesting use would be propulsion, both on planet and in space. You could put this tech in virtually every vehicle, provided the vehicles are designed to have the target "golf balls". This also illuminates how much easier it is to use if the gravity machine is attached to the target it's trying to move. The gravity machine would no longer need to be able to move the gravity point. Instead, it would only need to be able to create the gravity point in a specific space relative to itself. [Answer] # ASSUMPTION Assume gravity fields behave similarly to magnetic fields in that we can send some thing through a wire/pipe to generate excess gravity field than what you would expect and follows a sort of right-hand rule. (Perhaps through [relativistic mass gain](https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence#Relativistic_mass)? Maybe a little fantastic there!) # THE MECHANISM: SOLENOID AND FIELD NEGATION Have you ever heard of a [solenoid](https://en.wikipedia.org/wiki/Solenoid)? It does this nifty thing where the magnetic field inside is very strong but practically non-existent on the outside. (Try using [this right-hand rule](https://en.wikipedia.org/wiki/Right-hand_rule#Amp%C3%A8re%27s_right-hand_grip_rule) on a wire in solenoid configuration to see why!) We could use the above mechanic to negate most/nearly all the mass of a spaceship by having our gravity pipe wrap around the spaceship and produce a gravity field opposing the dominate one (a.k.a. Earth, the nearest major gravitational mass). Now that your spaceship has the equivalent mass of some piping, or maybe even negative effective mass, it is pretty easy to zoom around! Bonus points: Since you are negating mass, fast-as-light travel becomes much more realistic. You may even get away with things like an [Alcubierre\_drive](https://en.wikipedia.org/wiki/Alcubierre_drive). (Okay, if these fields are generated via star-trek like nacelles, you place one in front and one behind you, not side-to-side. Funny looking ships ensue!) This, of course, assumes you can producing the opposing gravitational field is less 'expensive' (in terms of energy, cost, etc.) than simply adding more rockets/fuel. # OTHER APPLICATIONS Hey, why stop with something so mundane as space travel? If you go into a deep enough gravitational field, time starts acting odd (due to a theory of relativity!) and you can effectively put people into 'stasis'! (It's not cryo-sleep, its gravo-sleep!) What about zero-g architecture; why not live in cities in the sky if we can power anti-grav stuff with, say, nuclear fission/fusion? What about floating solar power plants to beam stuff down into cities? Grav guns (perhaps ship based?) and grav traps also become things. One of these solenoids could be incorporated to a launcher, while a straight cord could increase gravity to "pin" people/objects/vehicles down. Grav-mining may also be a thing- rocks are much easier to move when they weigh less. So maybe a mining operation lifts rocks in volume, miners 'sift' through it, and then they simply de-activate the grav field, letting the remainder simply fall back in place. I guess what I am saying is that the ability to generate gravitational fields, even if it does require large (but not unmanageable) amounts of energy, is a game changer for transport, weapons, architecture, mining, politics, humanities, and more. It changes so much. [Answer] As others state, it seems your ideas are pretty far from our current understanding. However, as we're world building, let's imagine we can have an "electro-gravity" device, that when powered up "makes" gravity, in the same way as an electromagnet "makes" magnetism. The first assumption is that you can reverse the polarity of the gravity. That's a rather big one, as (so far, I think I'm right in saying...) we've never observed or really even postulated the occurrence of anti-gravity. Therefore, to get your object on Earth into space, you'd have to have your grav-o-matic in space to begin with. You could turn it on, create 1G and then enjoy all manner of objects from the surface of the earth (including the atmosphere), in orbit around the Earth, and then even in orbit around the Sun all starting to head your way. That leads on to the next assumption: you'd need to be able to direct your gravity into a "beam", and ideally to a specific distance. Here again, we're a long way from known physics. Without making it directional though, you have other problems. By example, lets we put your grav-o-matic in space, and set it up for 1G. That "neutralises" the gravity on the surface of the Earth below the gravo-matic. However, gravity is only zero at infinite distance, so on the back side of the Earth, the gravity is now 2G. Likewise, the gravity on the space-side of the grav-o-matic is 1G, plus the 1G from the Earth (so 2G again). Say nothing of the gravitational effects on your grav-o-matic itself, which will most definitely be headed Earth-ward when switched on. Suffice to say, manipulation of gravity is seemingly simple and convenient yet makes, arguably, the most complex problems of world building. Since you mention handwaving, perhaps instead you can conjure up some sort of super-magnetic material (that perhaps uses some other force, not traditional magnetism). Now your grav-o-matic doesn't generate gravity, it generates this other force, which "pulls" the material (with the thing you want to launch attached) into space. Now the force that leaks into space doesn't affect anything except more of the special material. Even this is full of "plot holes", but as I say, this all presents a lot of challenges. [Answer] I've used something like this concept in a worldbuilding project before! The idea was Humanity never really abandoned rocket technology and we essentially railgunned all of our ships into orbit. That was it. Brilliant, ham-fisted efficiency. The ships were AI-guided to a space elevator where their crew was awaiting their ship, since the G-forces of getting catapulted into orbit would Probably Kill You. I later abandoned the concept and went with a lower-power jump drive that sent the ships most of the way out of the planet's gravity well, but for a time I almost made it work. My idea for an artificial gravity-assisted launch would probably be in a similar vein, but gravity being gravity, it's a slightly more difficult of a concept than just launching spaceships into orbit from a giant cannon. As far as the similarities go, I would say they begin and end with the general concept; generate enough force, and it sends your ship into open space real nice and quick. Way easier than all the nonsense with orbits and gravity and what-not. Where it gets complicated with artificial gravity, I would say, is how its generated, and also the theoretical physics question of 'how do two completely different gravity systems interact with one another when one is a planet and one is generating enough gravity to both counterract the influence of gravity on the ship and reverse it enough to get it offworld'. I have some issues here before I expand on this further. Artificial gravity really only ever works inside large space structures such as space stations or even really large spaceships with those big spinning rings, via centripetal acceleration. This works because they're in an enclosed, localized space immersed in zero gravity-and even then, there's a lot of if's and maybes involved and most sci fi worldbuilders ime just apply a heavy topical spread of handwavium cream. This specifically, though, could not really happen in the real world as we understand it currently. This is essentially the reverse of a thruster on an incredibly large scale-instead of creating a stream of mass in one direction that pushes the mass it's connected to in another, you're asking all the force to move the mass as it moves out. This would have to both negate and then counterract the planet's gravity, and even then be focused enough to push the large craft directly up, with a somewhat controlled spead as to not launch it into a dangerous trajectory. With that out of the way, let's make it work with my favorite worldbuilding tool: rebranded sci-fi themed magic. We have a payload and a need to move it using artificial gravity. I would probably go about this by havving four large pylons denoting the altered gravity zone. Depending on how large your large spaceships are, this could be part of a planetary spaceport or a large part of the ocean that giant spacecrafts occasionally emerge from like cosmic horrors rising to reclaim the universe. This zone would somehow create a sort of direct beam that would push the spacecraft from the surface and out into space (Maybe it's enerated by the pylons? The gravity machine might be located directly underneath the landing pad?). You could call this gravity, I guess, but functionally it's more of a reverse tractor beam that I'm visualizing - which would most definitely have to work through magical means, but that's not the point here. Another thing you could do is have small, artificial gravity-propelled drones work like tugboats, literally pulling the ships into space. They might also be further assisted by smaller objects that attach to the ship and propell it as well, to reduce the strain on the main drone. and operate faster. This is completely unrealistic, unfortunately, but it still is a very interesting concept and I hope that my responses could help you come up with a solution! [: ]
[Question] [ An athame is a magical item that is created to reflect and direct psychic energy. To create this tool, one cannot simply enchant ordinary weapons to give them magical properties. Rather, these items must be built from the ground up, through special materials, ingredients, and rituals. The process can take months or even years to complete, but result in an item reflects the emotions of the user. Athame can take various forms, such as knives and swords and other weapons, or mundane items like a chalice or a book. As the athame absorbs the pshyic energies of its wielder through constant use, it grows more powerful. Through this symbiotic relationship, a great and noble hero can produce a powerful weapon imbued with his positive energies, such as Excalibur. Likewise, a notoriously evil warmonger can create a negatively charged item with evil properties that is geared toward causing pain and suffering. Even though athame reflects the psychic energies of its user, an item wielded by an evil character always maintains its stain of corruption. The negative energy that the item absorbs cannot be changed to a positive state. It retains its evil properties even when being wielded by a noble character. In fact, the item can begin to corrupt that character's nobility, turning him darker until he begins to reflect the negative energy the item imbues. This attribute doesn't work in reverse. An evil character who uses a weapon previously owned by a hero will not take on heroic qualities and reflect the positive energy of that weapon. Instead, that weapon becomes corrupted, and its declining state into a darker version of itself cannot be reversed. It would be easy to say that negative energies are stronger than positive ones, but this is stupid. Powerful emotions exist on both sides of the spectrum, and can lead to characters who feel them strongly. There is no difference in commitment between a Hitler or a Mother Theresa. Why would this transfer of energy only occur in one direction? [Answer] ## Good works CAN cleanse a stained item, BUT... From an abstract perspective, a tainted item can be made less tainted by being used for noble ends, just like a holy item can be corrupted by being used for wicked ends. However, because a tainted item corrupts the user, the user will (usually) behave in a less and less righteous way, ending the "cleansing" effect of the item long before a significant impact has been made on the item. In theory, if enough consecutive Saintly Mother Theresa's were to each use the Corrupted Chalice of Malice for good ends, and each Mother Theresa stopped before she was sufficiently corrupted to start doing bad, eventually the Corrupted Chalice of Malice might be cleansed. But you're going to hurt a lot of Mother Theresas in the process. Then why doesn't a holy item redeem a villain? Why doesn't Excalibur purify your Alexander the Bloody Conqueror and make him into Alexander the Glorious Guardian? Maybe it does cleanse him, a little. But, again, the dynamic is such that corruption sets into the item long before Alexander is redeemed, and the positive influence is thus diluted and eventually reversed. Remember, a glass of pure water mixed with a glass of filthy water gives you two glasses of dirty water - except in this case, when both your glasses (the user and the item) are filthy, they both grow filthier and filthier. --- Caution: if this is the way magic works in your world, there will likely be people who, with good reason, suggest that magic is basically evil (or at least magical items are). While not precisely the truth, it strikes near enough to it; nearly every ancient, powerful item will be stained with corruption, because at least one user will have used it for bad ends. And if you once begin to do evil while you have any item of power, you're likely to be dragged down by the item's "evil inertia" into wickedness. Unless there's a counterweight (greater power for pure items, evil settles out of unused items even as the power remains, etc), this system over time gives greater power to those who are selfish or corrupt than those who act for righteous ends, because the world will collect powerful corrupt artifacts, and non-corrupt artifacts will tend to be corrupted. [Answer] I think an interesting approach to take is the view of entropy. In physics, entropy is the amount of disorder or randomness in a system. A chaotic and random state is seen as the natural state, while a highly ordered system requires a lot of energy and effort to create. Despite this energy and effort, though, entropy always increases over time, with only more energy and more effort able to reverse the ordered system's deterioration. I imagine the corruption of objects as you describe to be similar to this. Evil is generally viewed as the morally wrong yet easy way out. If you need the information, it's easier to torture it out of them than painstakingly interrogate them. If you need to get from point A to point B quickly but have no transportation, it's easier to steal a horse then try to convince the owner that your need for it is great enough for them to just give the horse to you. In this sense, the natural state of being is evil. In other words, one might say that the "natural state of man" is savage or morally inept, and only through intense effort and energy can we build and maintain a society based on laws and morals. Therefore, it makes sense that magic items as you describe would tend to devolve into evil or dark states naturally, and even immense effort to make them good would only do so temporarily. There is always a "pressure" or movement from order to disorder, from light to dark, from low entropy to high entropy, and from good to evil. [Answer] "Good" and "evil" are merely human labels; psychic energy is just psychic energy. A simplistic definition of "being good" requires adhering to certain rules (no killing unnecessarily, no stealing, no torture, etc.) even when it would be more convenient or pleasurable to do so. Wielding an "evil" weapon exposes the mind of the wielder, through its psychic energy, to the past mental states of the original wielder that made the weapon "evil" and there's no way for a mind to unsee things, which is what makes this process one-way. This repeated exposure gradually acclimatizes them to the idea that breaking these rules (initially for a good cause, of course) is an acceptable shortcut. They might, for example, torture a bad person to get information to save others out of expediency where they wouldn't before. This gradual wearing away of the societally ingrained mental rules against doing things that are evil turns the user of the weapon to evil and further reinforces the "evil" psychic energy of the weapon. [Answer] Going to the negative states breaks the seal of positiveness of the items. There is no turning back. It's like when you buy an action figure or another collectible item, and just cutting open the sealed package kills its values on the market of collectible (no matter if you actually used it or not). A seal is a seal, once it's broken is no longer intact. Those on the positive state rely on the seal to channel their energy in the right direction, which otherwise would flow also toward the negative state. [Answer] Items are fundamentally jerks. It sounds harsh but it is true. Magic swords find it humorous to trip their users. Magic books revel in causing paper cuts. Magic shotputs want to be dropped onto groins. Stuff is just mean and bad because god made it that way. If you magic something up and force goodness into its pores it really is against the nature of the thing - kind of like a nice cuddly cat. You really need to mess up the whole catness of the beast to make it sweet - you breed in flat faces and kibble hunger, etc. Magic items are the same way. It is possible with great effort but it goes against nature and it is a big lift to make anything good. But turn a cat loose into the wild and cuddliness and flat face notwithstanding it will turn into a bitey jerk cat in no time and that is that. Even if you catch it and bring back cat treats and pillows it is going to be a bitey cat for a long while. The same with magic stuff. If you give any of it a chance to be bad that is in accord with the natural entropy of the world and once bad, bad it stays. That is why just about every object (magic or otherwise) you find in the world should be considered to be bad by default. Be suspicious of your things. Always cut away from you. Shotput safety at all times. [Answer] It's because "user" is a loose concept when it comes to magic items. A magic sword does passively gain power from its wielder but it also gathers power from anyone it is used to kill or hurt. This power is almost always negative as there are very few people who enjoy being stabbed. In the case of holy and good aligned items there are techniques and enchantments that aid in cleansing these energies before they enter the item but these are things the wielder must actively do to keep the stain of negative emotions out of the weapon. When someone who doesn't care how good their sword is, or someone who isn't properly trained uses a holy sword it allows negative energies to enter the item and begins to slowly change its nature. This tends to lead over time to most magic weapons being tainted with negative energies over time as eventually over the centuries it gets used by some one without the proper training. However this also tends the other way with items that are helpful like a jar that produces infinite water for a town, or a bandage that removes pain tending towards good energy as everyone likes it and is happy those items exist [Answer] "Good" and "evil" are not equivalent in nature. A man who murders one is a murderer. Perhaps a man who lies once is not yet a liar, but certainly a man who tells a lie once out of every ten things is a liar. Evil is a flaw in a good thing. As with a crack in a pail, little of it needs to be damaged to make the whole thing a problem if useful at all. [Answer] ## Good and Evil aren't counterparts Many people speculated that good items should redeem evil users, or good users should redeem evil items... but the scholars in psychomechanics have determined that this idea is based on a flawed conception of what is good and what is evil. Where popular expectation is that good is positive and evil is negative psychic energy, it's more accurate to think of the distinction as being one of extent, rather than sign. Good is restrained, cautious, and thoughtful, and Evil is the result of not abiding by that cautious nature. Hence the phrase "too much of a good thing" - emotions that are "negative" are just as valuable to good people as "positive" ones are. A healthy amount of sadness, of anger, or fear are important, and are to be valued equally with happiness. Righteous fury is carefully-wielded, and bravery arises from carefully-controlled fear. A healthy level of envy can drive a person to greatness. However, extreme sadness, extreme anger, extreme fear, extreme envy, even extreme happiness can lead to destructive behaviour. What makes a person, or an item, evil isn't the emotional energy itself. It's the healthy boundaries that are attached to the energy. An evil person draws more energy from the item than is healthy, and the item becomes adapted to this extremeness. A person wielding an evil item is encouraged to push the boundaries, until they break entirely. A good person wielding an evil item is still feeding it the same psychic energies, but the item lacks the boundaries that define the goodness of the energies. An evil person wielding a good item is feeding those same energies, too... but they're flooding it with the energy. Much study has been done by scholars on whether items influenced by evil can be restored, whether the boundaries can be rebuilt - but the jury is still out. It has been shown that those people with the strongest boundaries can withstand the corrupting effect of an evil item for much longer than most, but the temptation to allow the energies to intensify beyond one's boundaries is always there, and each time you relax your boundaries, it becomes easier to relax them further. There are rumours of a few individuals who have successfully rehabilitated an evil item - in all of the stories, it's implied that these people had to effectively train the item, rather than simply using it. But no serious scholar has been able to verify such stories. ]
[Question] [ First question ever asked, so apologies if I've done this incorrectly! My current predicament: characters in 1931 Las Vegas are looking to get their hands on some neon/argon (for use in neon signs). I'm wondering where, realistically, they might be able to obtain some. Is it conceivable that they would be able to create some themselves via fractional distillation if they had adequate equipment? Or would a whole air separation plant be required to create enough neon? One character is a chemist with experience redistilling industrial alcohol to make it potable during the Prohibition period; would any of this experience translate at all to distilling gasses? This is also happening while the construction of Hoover Dam is going on -- would there be any equipment or resources at the construction site that might be of use? I've looked into Georges Claude and his air liquefaction business, plus the history of neon and the construction process of Hoover dam, and while I've learned a lot more than I first knew, I'm still lacking the specifics of exactly how this process was performed with 1931 technology. Grateful for any resources you can point me towards, huge thanks for helping me out with this! [Answer] Los Angeles? Salt Lake City? Or maybe even someone local by 1931. The first neon sign in Las Vegas went up in 1928. [![overland hotes](https://i.stack.imgur.com/d5H1f.png)](https://i.stack.imgur.com/d5H1f.png) [![overland hotel](https://i.stack.imgur.com/BZzZC.jpg)](https://i.stack.imgur.com/BZzZC.jpg) <http://captainhistory.com/wordpress1/2018/02/25/the-first-neon-signs-in-las-vegas-nevada/> If you want there to be some adventure and finagling involved your characters could go on a road trip to Los Angeles, which would be a good contrast with Vegas. But there were several other establishments in Las Vegas with neon signs in the late 1920s and by the 1930s it would not surprise me if there was a local outfit to provide them. Wikipedia says the [first neon sign in the US was in Los Angeles](https://en.wikipedia.org/wiki/Neon_sign_) in 1923. --- The other possibility is that they could use hydrogen. It is easy to make hydrogen with electrolysis of water. Clearly hydrogen was used for some signs; it would be so much cheaper I am not sure why it was not used for all signs. I think it is either because neon gives a better color, or the hydrogen reacts with the electrodes and the sign life is short. --- Another possibility: they could use helium. [![gas discharge tubes](https://i.stack.imgur.com/TNUlj.jpg)](https://i.stack.imgur.com/TNUlj.jpg) <https://en.wikipedia.org/wiki/Gas-filled_tube> Helium does not make that eye-popping red color that neon does, but it is bright and colorful. Also the US in the 1920s had lots of helium. The [National Helium Reserve](https://en.wikipedia.org/wiki/National_Helium_Reserve) was founded in 1925 to store all the helium being captured from natural gas operations across the Great Plains. I could not find when helium became available for sale to the public, but it was being used to fill airships before the Helium Reserve came to be. [Answer] Simply buy it. [Neon](https://en.wikipedia.org/wiki/Neon) was commercially available, although probably not terribly cheap. [Linde Air Products](https://en.wikipedia.org/wiki/Praxair) was founded in 1907 and still exists as Praxair. They were the main users of [Carl von Linde](https://en.wikipedia.org/wiki/Carl_von_Linde)'s patents and processes in the USA, and would have been an important supplier to makers of neon signs. You don't need a great deal of neon for signs, which is fortunate, since it only makes up 1 part in 55,000 of Earth's atmosphere. Argon was used as a [shielding gas](https://en.wikipedia.org/wiki/Shielding_gas) in welding. That consumes far more gas, but argon is cheaper, since it makes up nearly 1% of Earth's atmosphere. I'm fairly sure it's used for this because it is the cheapest "noble" gas. There might well be a company in Las Vegas that acted as a distributor for industrial gasses, but if not, there should be one in Salt Lake City. [Answer] I doubt very much that Neon (<0.002% of the atmosphere) or even Argon (<1% of the atmosphere) would be extractable using any form of home made equipment in the 1930's. With sufficient time, money and know how I'm sure it could be done but its not the sort of oporation to run in your garage. Far easier to buy some, both gases were in use in sign making from the 1920's so anyone sufficiently determined could have found a source. Alternatively they could have attempted to construct a small cryogenic plant from non standard parts, I know which way I would choose. ]
[Question] [ # Quick Overview Here's the situation: your species, under directive of your friendly world government, has been informed that all "natural" (aka reproducing like your normally would and having a child that way) birth is now going to be "phased out" (made progressively illegal/impossible) in favor of mandatory genetic engineering. Why? To eliminate any and all genetic defects, select for only beneficial genes ala GATTACA, and secretly control reproductive freedoms under the guise of progress. The end goal is to have all future children born in government gene clinics only, meaning it should be effectively impossible or inconceivable to have a child outside this method. Some sci-fi tech is available to this species and government, gene modification being the obvious one. Identification microchips are widespread in first-world countries, cybernetics are as common as smartphones, and general AI is being used by the WG (world Government) to maintain its otherwise byzantine bureaucracy, design its laws, and automate federal industries so logistics and budget are not as serious of an issue here. Assume global mass surveillance tech is feasible via drones and recognition software, but that it would take some time to implement and scale to that level. However, there are a few serious problems that this civilization will have to overcome that are immediately apparent to me. ## Paging Dr. Bureaucratic Nightmare 1. There are approximately seven billion people on this planet, a vast majority of whom not genetically modified or modified in small ways. Genetic modification was entirely up to the individual before this measure, though very expensive. 2. Despite there being a "world government" it does not hold total sway over all nations in terms of sovereignty due to a wide variety of politics, cultures, development, and religions influencing members (which makes mandatory genetic modification a difficult sell, especially in religious areas). However, some utilities companies (water, electricity, etc) around the globe are directly WG-owned and provide necessary and life-saving assistance for millions, especially in undeveloped regions. There is a gene-modded secret police branch in almost every developed country, but undeveloped ones do not have one. 3. There exist many, many ways of life for families, especially in undeveloped countries that lack modern infrastructure to connect distant villages and other rural areas. 4. The internet is still a thing and access to information is not as limited as it could be. Dissenters will be an issue, and protests are inevitable if this operation is too overt. ### The Question If this government is going to succeed in its end goal, how would it go about doing so? I'm open to any answers, though I'd prefer ones based on relevant science concerning reproduction, childbirth, etc. If there is anything I'm missing or should clarify, let me know! [Answer] # Social engineering Firstly, expect this to take at least three or more generations to take full effect, you're in for the long game here. ### Step 1. The medical service Many of the groups more reluctant to move socially with the times also suffer from recessive genetic conditions. They do make use of genetic testing to ensure that both parents aren't carriers, but you're now providing a service where the children definitely won't have the condition. All you have to do is use our gene editing service and you can be free of this concern. Along with this you're aiming to replace IVF and other similar services, child without the same problem guaranteed. The guarantee being free use of your services if it turns out the child does have related difficulties, but that's all part of the plan. ### Step 2. The lifestyle service [Too posh to push](https://www.nhs.uk/news/pregnancy-and-child/too-posh-to-push-mums-a-myth/)? Goodness me no, I'm too posh to carry the baby at all. For the busy executive who wants to have a baby. Don't worry about the pregnancy, we'll deal with that while you carry on with your life. Collection in 40 weeks. No birth defects guaranteed! No genetic abnormalities guaranteed! Above average intelligence guaranteed! ## Now you're on a roll The rich and powerful are now seeking out your services, as are those having children later in life. ### Step 3. Aid for disadvantaged countries We're back into medical services here. Our target is to completely eliminate maternal mortality in the developing world simply by encouraging every woman to use the service along with the free lifetime contraceptive supply. No more risk of dying in childbirth, who could ask for more? ## It's only later that you start making things hard You're now established both as a medical necessity and a lifestyle choice for the wealthy and aspirational. You're embeded as an essential service in minority groups and across the developing world. Only at this stage do you start making it difficult for people to go about things the natural way. Anyone can use your services, given the risks, why would they not? At this stage you start limiting access to "normal" maternity services, fining or otherwise socially penalising people who have natural children, but use of the service must be entirely normalised before you take this step as must free lifetime contraception for all. Can't be having any accidents. And we've only openly offered two very small groups the genetic services. The wealthiest and the most needy. [Answer] ## Expanded Child Abuse Laws The best way to get these new measures into law is to NOT make your goals clandestine. When you start trying to hide your intentions, you put yourself into a position to have your activities exposed as 'evil' which will strengthen your opposition. Instead your goal needs to be to shift public opinion to agree that this is what is best. There was a time not long ago, that hitting a child was not just okay, it it was expected. The old adage "Spare the rod, spoil the child" comes straight from the Bible and a large portion of the religious community opposed anti-child abuse laws believing that corporal punishment was a necessary part of God's plan to raising good children. As such, nobody really saw it as abusing a child because people believed the benefits outweigh the harm. So, to overcome this, opponents of corporal punishment made two seperate pushes. One to appeal to the secular population by publishing scientific studies to show how children who were not spanked so much turned out better as adults. And another that appealed to the religious population by citing contradictions and vagities in scripture to show how it could be seen as the will of God not to hit your children. This two pronged approach created a lot of attention to the concept and stigma of "Child Abuse" making what was once seen as necessary a modern taboo. To push your Eugenics laws, you need to first prove to the secular community that natural childbirth is bad for the parents. Eugenics laws can be seen as improving one's freedom of reproduction by making it the parent's right as a citizen to choose how and when they reproduce. Sterilization with the option to reproduce when you are ready for it could become the final compromise between prolife and prochoice. No babies have to be aborted, and no woman has be be forced into an unwanted maternity. So, state healthcare stops covering abortions (because these are murder after all), and instead covers sterilization and artificial post sterilization pregnancy. Once optional sterilization becomes normalized, people will begin comparing the lives of those who chose when they give birth to those who do not. Studies will flood in showing greater successfulness of people who get to choose which will lead to the inevitable conclusion that not getting your children fixed is bad for them. This is when religious opposition will become your big hurdle. Each religion will need thier objections overcome individually, but in general, once people WANT this control, they will find ways to make thier faith work with what they want to be true. If you take Christianity as one possible baseline, the initial opposition will say that God made the human reproductive system and that we have no right to interfere with it, but those who want to interfere will step in and talk about how we were made in his image and given dominion on Earth and that it is part of his plan that we progress to be more like him as we mature as a species. It will take a generation or two, but after your religious communities live alongside the secular communities who are clearly doing better, they will come to want what they don't have. Once you have enough support from religious communities to atleast make the case you are not being plainly heretical, you can transition from Eugenics being the suggested way of raising kids to to the required way. At this point you are not taking away a parent's right to choose how many children they have or of what kind, but you are declaring that having natural children or too many deprives the children of opportunities. This in turn is labeled a form of child abuse which you outlaw. [Answer] ## Make yours better first, eliminate other later Your first goal is to build enough GCs (Gowerment Clinic) to be able produce the right quantities of childs. (If you want decrease population, you will do it later. Now you want to be able satisfy all requests - or at least nearly all) Those childs would be genetically enhanced in the process, to be more successful (inteligent, pretty and more resistent to illness) - if you are starting this technology, there would be not much enhancement first, but as it will widespread, it would became better. This would them make more attractive to parents, than natural one (no problems with pregnancy, better results in school and life, less hurden with child illness - so better life quality for parents). You will start to offer it as a priviledge to rich, bussy, celebrities etc. and actively promote it in press - less "she is pregnant" titles, more "She get the perfect child" and "The child is soo much wonderfull". Also hire someon from Apple PR section for the campain :) Not all would opt in, but many would and your capacities at first are limited anyway. (On the dark side you secretly support movement "Why only rich can get all the best, we want too".) Once you can mass produce childs, you go down with the price (at public request ofcourse) and even subvent it, so the middle class could affort it easier. (You need more requests, than you are able to fullfill just now, to be able pay for increasing production capacity and justify it - you still support the first movement too. You start also opposing movement "It is unnatural" and put the right figures in it - such, that would be easy denounce and keep huge stream of scandals about them - to discreditate the "unnatural" idea with its protapagators. And you also secretly support antivaxers. Also make some vaccine scandals and as consequence request more testing, more burocracy and more effort to prove, that new vaccine is really-really safe.) At the start simple media manipulation, curiosity and beneficity of results would create the demand. Once you are near to be able supply enought to satisfy the natural demand, you need to go futher and decrease the prices again (yes, you are allready selling below the cost, but you want to offer it cheap and later totally free). Some funds could be drawn from common medical support (well GC are medical too, just redirect more funds their way). Let independent sources notice the fact, that the new childs are more healthy and less prone to illness (not totally imune, but less prone and have lighter symptoms in case of sickness - support such reports, discourage opposite one). This can be reached in one or two decades and many of your childs are in school already, much more growing up to this age - they became seen as "normal minority", not just something "experimental". Even poor families can now affort to have one and there will be some allowances to rise one (under many exuses as "medical research data" and "right child care" and "propagation of better health for everyone (well it goes just to those, who have it engeneered from birth so guaranted)" ) (and you would tolerate abuse of the system, because you want to have as much of such childs as possible - even in you ideal world would be need for garbage-collectors). With growing antivax movement, lower clasic medicine funds (and maybe even with little dark support) more normal illness would spread, and also their little more agressive variants. Superiority of your childs is visible and "common knowledge" (well even when not "vaxed", they was getting some "immunisation" while was created from the start and as part of the process), while widespread of disseases is also nothing new. Your milestone is about 1/10 of new population in developed countries came from GCs (or some similar sources - you cannot totally suppress concurecy now, but at least they have to stand to some "quality standards", including full immunisation. And well your prices are really dumping, so only rich would choise alternative source). Even in undeveloped countries there are GSs and your childs are at least tolerated. When first vawe of your childs is mature and good portion of them is successful in their jobs and planing to settle and create families, some pandemy occurs. Say like COVID-19. Youre childs are good, usually does not affected at all, the rest have just little problems. Their position in society is hardened and they will opt for GCs childs more, then for "natural". Yes, even their natural childs would be better than average, but it is not problem now, you are good with it - even you push it in media as much as possible. At this scale it is clear, that your "new race" is better, but still is everything fully optional and now everybody have a choise - natural or GC - and can get what he/she want. Finally pandemy is over, your "race" is still minority, but really successfull minority and for more and more people is going to give their offspring the best they can - born in GC and be one of those successfull new people. As usual their are conspiration theories everywhere (as they are in Real World today), but it is normal. And well, some of new childs was affected too, after all. Some even died. (Well mostly those with unhealty life and preconditions, but propaganda does not care - they died after all.) Normal desseases are more and more common now (antivaxers still get their support and new vaccines are stil harder and harder to develope and take longer - all for "public safety"). GSs are still delivering for free (or just nominal price) and are everywhere. The population is growng much more, than before - as you produce your growing share, but natural born is still common too. Time to reduce it a little. Time to next pandemy, just little more lethal - lets 1/10 of total population die. Mostly those normal born and so even more problem for developing countries and religionar people, who are natural-born strict. It is bad, but world will goes as usual, 9 from 10 people survived (or 7 from 10 in some localities), so it could go the normal way. And we have medially survived second pandemy. Yay! Now is time for even more media push on how the GC born did a more better, then average population. Get more customers, get more share and prepare for future. Normal dissesases gets their toll on natural-borns, it is something normal. Now more than 1 of 4 newborns are GC originated. For next decade we finally came with our secret card. This time the conspiracies will became true, but as it was proven false before, nearly nobody would trust it. We really have (be it from start or developed in last 60 years with growing GC born population) artifical virus designed to be mostly lethal for those without specific gene sequence and nonlethal (but still infectious) for those, who have it. And it would also hit at fartility of anyone infected. Not fatally yet, but hard. As the normal status is to have a lot disseases around and sometime pandemy, it is just bad case this time. And all are hit on their fertility, even GC borns, so it is harder to multiply naturally and more work for GCs to fill the missing population. In next generation GC borns will be majority and you are big step nearer your goal. And with a lot and constant decimation of population, it would slowly change to work in such situation too. Couple of decades is long enought time for that (compare life now and before WW 2). Your GC borns are able to carry all the work somehow, at the worst, but there is still a lot of natural born around. Also many are fertile (both Nb and GCb), but now it is time to reflect the situation and slowly modify the law to more and more propagate GCb - for critical positions it would be "high recomended" to hire GCb as there is better chance, that next pandemy would not paralyze the life as much as previos three (or four). The natural born is now officially presented as worse choise (as smokig, or drinking for example) and so some penalties are applied, some allowances are withdraw and each iteration it is more and more restricted. And nobody yet realised, that from some point all GCb are created infertile - they are too young yet, fertility was affected by many desseses and mainly by last pandemy and GCb usually opts for GC anyway. You are nearly there. You can build-in new sequencies in GC for next generation, you can select on that sequence in pandemy later and erase all those fertile yet from the first "not-so sofisticated" GC borns from times, when infertility may be seen as "issue", (and erase all natural born too - if they are not in constant quarantine, their are dead, if they are in, they do not matter anyway - they not have resources to multiply adequatly). With regular updates to genetic sequencies you get not only better workers (at your choise mor inteligent, obedient, whatever) but also marks to target, if you need erase older models. --- And for start you need "just": * genenetic technology * unlimited funds * global influence * one totally hidden and isolated virus laboratory with few mad genius scientists inside (this is only addition to your question - and military of all superpowers already have some today ) And 100-300 years of time. [Answer] You're not thinking evil enough As has been said by other writers "anything is possible when you just stop giving a [expletive] about the well-being of other people". So let's turn off our empathy and common sense for a moment and think of the simplest, most easily implementable solution to the problem. There are a lot of problems with ending natural reproduction across the board all together. Cost, inequalities in the access to genetic engineering and contraceptives across the world, the fact that the world is full of varying opinions and beliefs on any given practice, the fact that humans have never been good at avoiding sexual contact in general. It's a lot of factors to consider and makes it really difficult if you want all seven billion human beings on planet Earth to never have a natural born child ever again. This is the exact problem faced by the World State in [Brave New World](https://rads.stackoverflow.com/amzn/click/com/0060850523). In the history lesson at the beginning of the novel the speaker portrays the formation of the World State as social "progress", but also mentions global war and pro-World State governments putting contraceptives in other countries' water supplies, along with the well-known plot point of almost the entire population of Earth being in-vitro designer babies. This leads to some rather unpleasant implications. Rather than people converting to the World State ideology because it was better in some way or because it offered things that other governments could not, it implies that the proto-World State government just killed everyone, bred a new batch of humans and told them that the World State won because it had the superior ideology. War doesn't determine who is right, but who is left. There's your solution: kill and/or sterilize everyone (or at least everyone that isn't thoroughly indoctrinated into your ideology) and then breed a whole new population of humans to replace them that is born sterile and genetically/socially engineered as you see fit. This is also the way to deal with issues in maintaining status quo (just breed all your new humans to be sterile), logistics (because instead of seven billion people you just have to worry about however many you whip up in your lab), public backlash and difference of opinions ([because they're all dead](https://www.youtube.com/watch?v=NI9nopaieEc)). This is also one of the few ways you will be able to make sure no babies are ever born outside government clinics in any country (especially in places like the Third World where people are harder to track as your question states), because otherwise someone is going to disagree with your mandate (see: anti-vaxxers) and try to have babies naturally off the grid. The only way to maintain complete homogeny on a certain topic with no freedom of belief whatsoever in any population, much less one that spans the entire world, is through totalitarian, draconian measures. Is this an evil, nightmarish solution that would make [even the most heartless social engineers wake up in a cold sweat](https://www.youtube.com/watch?v=ybSzoLCCX-Y)? Yes. But you're a dystopian government, caring about other people's lives and freedom of choice over your own policy was never a high priority of yours. [Answer] If it truly is a total world government, with total dictatorial control, then the easiest first phase solution is to make birth control mandatory. And I am not talking about voluntary birth control. Mandatory birth control additives to all water supplies, for instance, or all grain supplies. Then, once the average normal female is unable to conceive, all future generations are 'artificially created'. They would be fertilized, and the effects of the birth control reversed, only in specified government facilities. This, of course, would cause the world population to drop dramatically and significantly. I can not imagine that the government, no matter how big, could implement a test tube breeding program large enough to maintain the global number of births today - 53 million in 2020 as of May 18, 2020. Once the government has full control over the genetic composition of the embryo, the next phase would be to eliminate all genes that result in 'lust' or 'desire to have sex'. Once the sex drive is eliminated from humans, there is no further need for universal fertility control. Females would see conception and birth as just a medical procedure, and if the government is content with the population size, it may be 'just another paid job' for them. That is, females would have no desire to be mothers, nor would they have any desire to have sex to become mothers. However, under the Law of Unintended Consequences, there might be three that I can foresee. First, there would be no need for males and the far inferior Y chromosome. There would be two 'sexes', one that is strictly for maternity, maybe even specially bred, and the other just for labor (like bees). The second unintended consequence, is that given the dramatic drop in fertility and births, fringe populations such as extreme orthodox groups who have established their own water or grain supplies just might become the majority. Groups that have 'caught on', and are resisting the government initiatives, could become the largest population group. They would, of course, oppose the existing government. The world is a very big place. It would take a few generations for the government to completely eradicate any 'independence gene' and turn humans completely into a herd animal through rigid social engineering. It just might require genocide and infanticide at a massive level, or mandatory forced sterilization, to completely eliminate the non-compliant sub-species among humans, even with strict fertility control. This, of course, would come at a great cost to implement on a global scale. The third would be a very skewed population pyramid, as China has suffered with their one-child policy. The elderly would far outnumber the younger generation. Would this result in massive social upheaval, as the elderly became aware of the lack of young people to continue their 'family line'? How innate is it in the human psyche to expect your family tree to continue to grow? How innately embedded in our mind is the need for the survival of our own personal lineage? Once the elderly, the 'old guard', die off, the less this becomes a problem, but with life spans of 80 to 100 years, it would take at least a century and a half for this unconscious drive to be completely eliminated through genetic and even social engineering means. Again, there would probably be the need for actual culling of the existing population to achieve the goals. Would there be a large enough critical mass of population to overthrow the government? EDIT Another unintended consequence would be a lack of genetic diversity. I can imagine that, in order to mass produce enough designer embryos or whatever to maintain a population size that would be economically sustainable (labor demand vs supply, consumer demand vs supply), they would have to be selected by the 'consumer' from a standard off-the -shelf base model, much like cars are. You select the make and model, like hundreds of thousands do, perhaps to match your ethnicity, religion, or culture, and then add options like hair color, height, eye color, future occupation skills, and so on. So, eventually, you end up with 'every car, errr I meant child, looks the same'. A new fashion industry. New baby models change from year to year. Even Cabbage Patch Kids were duplicated. Second EDIT It occurred to me from another answer that one consequence, intended or not, is the ability to genetically engineer a resistance to some new absolutely fatal disease, be it a virus or other pathogen. The pathogen could survive in the genetically modified person, but would not in any way effect them, but to non-genetically-modified people, it would be absolutely fatal and untreatable. Thus, all genetically engineered people would have this immunity, but non-genetically-modified people would not. Once this pathogen is introduced into the general population, you would be certain to pretty much wipe out all of the non-genetically-modified people. Of course, it could also work the other way, for a plot twist. The genetically modified could be 100% susceptible, and the non-genetically-modified be immune. [Answer] A lot of what I had to say is already said by user2352714 but I think he makes it harder than it would be. Culling feral humans would be most economically done with engineered disease, for which the state has effective treatment that it generously shares with any who come in out of the cold. Part of the treatment would inevitably involve sterilisation but you don't have to tell them that. If you don't sterilise a random few they'll probably never work it out. If you set up like this you don't have to suffer a bad image. While I'm not keen on having anyone else's ideology foisted on me, I'm not convinced that this is any less ethical than attempting to fill the world with squalling spawn. I'm not interested in being a henchman, but if you need someone to run a secret island base staffed by top-heavy women in gold lamè bikinis then I promise you that I will have Mr Bond shot on sight, without discussion, double tap, then headshot after a mugshot is taken for verification. ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/154864/edit). Closed 4 years ago. [Improve this question](/posts/154864/edit) I am writing about a city inside a dome which protects it from an inhospitable environment. I would like the dome to have it's own self-regulating ecosystem, at least enough to provide rainfall throughout the dome. I think there will be at least 2 artificially maintained rivers or maybe some canals that will provide a source of flowing water to evaporate. I am wondering how the outside climate might affect the seasonal changes inside the dome, such as a rainy season caused by either hotter or colder prolonged temperatures outside the dome? Would this even make sense for a dome that is thick enough to protect the city from dangerous outdoor conditions? [Answer] Why is the dome the best solution? Think about the original designers of the dome - why have it? An answer to this question may answer your question. [![enter image description here](https://i.stack.imgur.com/KaIza.jpg)](https://i.stack.imgur.com/KaIza.jpg) The only reason to have a dome is to be on the surface of a planet, otherwise you might as well be underground in a large protected cavern. But why risk being on the surface of a planet? The only real reason is for light. Caverns supply much more protection against radiation, weather, atmospheric pressure differences. They are also much more readily occupiable, with little investment compared to domes. They are also more safe - domes can fail and be damaged easily, resulting in likely catastrophic failure. In fact, failure should be considered to be inevitable requiring constant maintenance. [![enter image description here](https://i.stack.imgur.com/wj5gf.jpg)](https://i.stack.imgur.com/wj5gf.jpg) Only in certain situations, such as high seismic areas, are domes preferable, but even then it begs the question as to still why it is there. If you need it for light to grow, for instance, crops - this can be accomplished hydroponically using artificial power sources more readily, with more reliance and efficiency. Perhaps the original designers of your dome like the psychological benefits of being able to see out, but if we are talking of a hostile environment I'm not sure if this is too beneficial for the risks. Your dome would need to withstand corrosion, heat, wind forces, radiation, dust, pressure, micrometeorites and unintentional or intentional damage - all the while being transparent and clean (otherwise no point...). It would need constant injection of power to either retain heat or lose it though the dome, whilst dealing with direct solar radiation. It would need constant maintenance and investment, for which any error could prove fatal to all who reside in it. Best choose safety and go underground if possible. [Answer] > > dome to have it's own self-regulating ecosystem > > > Since the dome has its own self-regulation, there should be no impact of external climatic phenomena in general. However, effect of external climate can at times be aggravated in terms of extreme events like cyclones, floods, heatwaves etc, which can impact the efficacy of the self-regulation system your dome may have. So you can have minor aberrations for the climate inside, the severity of which you can control as per your specific settings and advancement of technology. > > dome that is thick enough to protect the city from dangerous outdoor conditions > > > Also note, while dome may help prevent from hostile environment, it may not help against geological phenomena (earthquakes, volcanoes etc), so you may need to build mechanisms to counter them. [Answer] There's one part of a dome that people always seem to forget about, and that's the bottom. In order for a dome habitat to be viable on, say the Moon or Mars, it must be completely sealed off from the outside, because outside is the vacuum of space, or a thin, mostly-methane atmosphere. The problem is, the surface of any rocky planet is going to be a lot of loose sand and dirt, not something that easily forms an impervious seal. Even if you had your fictional transparent aluminum indestructible material for creating the dome, you'd also need to be able to seal off the bottom such that soil erosion doesn't cause a cave-in beneath you, allowing your precious breathable atmosphere to vent out. This means your foundation must also be made of constructed material, specifically material which will not allow any leaks under any circumstances, e.g. seismic activity on the planet/moon below. At this point, what you have essentially built is a ship, just one that stays on the ground. The rules for this would be the same as the rules for building an actual starship, or for that matter a submarine or sea-floor science lab. It is an enclosure on all sides, not just a cover on top. Even if you have soil inside for planting crops, there will still need to be a solid hull beneath it to separate you from the actual outside environment below you. The whole thing should probably be propped up on legs which can be adjusted in length, similar to antarctic research stations, because you cannot rely on the ground itself to support you. As far as seasonal effects, it obviously depends entirely on the environment of the planet or moon you're thinking of. If it's cold, you need to supply heat inside. If it's hot, you need to keep it cool inside. If there's no breathable atmosphere, you need to keep it tightly sealed and recycle the atmosphere you have. Most of this is fairly self-evident, but without knowing much about your planet's environment other than that it's "inhospitable", any suggestions would be mere guesswork. [Answer] It depends on the properties of the dome. Heat can move 3 ways: conduction, convection and radiation. Conduction is through a solid - like a frying pan. Convection is via fluid medium like air. Radiation does not require a medium and moves via electromagnetic rays. A dome means no convection: air does not go thru a dome. Radiation and conduction are still possible. If you have a dome made of 100 feet of granite, you will for all heating and cooling purposes be in a cave. If you have a 100 cm thick plastic dome it will not insulate to the same degree, and extreme outside temperatures might be enough to cause air temperature changes on the inside. The dome could conduct heat. The dome itself would get closer to the outside temperature and so too the air near it on the inside. I could imagine if you had a thermally conductive dome and it was cold outside, but your inside is humid with evaporating rivers, humid air would condense on the inside of the cold dome material and drip off or run down the side. If it was very cold ice would form on the inside of the dome. If it stayed cold outside this built up ice could get thick, and weigh down the dome or cause trouble when it fell onto the lands below. The transparency of the dome will also matter a lot. If you let a lot of light through, heat comes with it: radiant heating. That might be good if you want to heat the inside of your dome. If your dome lets no light through then radiant heating is not an issue. [Answer] According to your rules, no effect, though the dome needs to be tough enough to withstand the weather in the first place, otherwise the dome stops being a dome and the interior is now fully exposed. And with that out of the way, the only problem is temperature exchange. Except your dome is massive - it'd have to be to get clouds, which you want, and it requires the ability to produce heat to evaporate the water, thus requiring an artificial sun (unless you somehow have glass windows on the dome which are strong enough to withstand tornados/hurricanes/hailstorms/etc.) and you'd need to regulate temperature already. So the answer is 'assuming the technology to create the dome exists, the technology to regulate the weather also does'. ]
[Question] [ The fixedness of body plans varies widely across different types of Earthling organisms. At one extreme, you have things like tardigrades, for which every individual of any given species has exactly the same number and arrangement of individual cells, differing only in size; at the other extreme, you have things like mycelial fungi, which don't really have any consistent large-scale shape. At various points in the middle of the spectrum, you have typical animals and plants: all animals of a given species tend to have the same high-level shape (e.g., number and arrangement of limbs), even though they differ in small-scale details and may be different sizes, while plants tend to be similar in terms of the shapes of specific organs (leaves, branching structure, etc.), but can modularly assemble those mid-range features into wildly different large-scale structure--i.e., it is easy to find pairs of animals that are nearly identical to each other, but good luck finding two trees that grew in exactly the same shape! This modular construction conveys numerous advantages to plants, most notably the fact that they can sustain massive injuries and still survive--lop a third of the limbs off a typical tree, and it won't care, 'cause it's got or can grow spares. Lop off a third of a dog, and, well... you've got an animal cruelty case and a lot of blood to clean up. So, can we make a plant-style modular-type body plan work for more animal-like creatures? How would something like that evolve? Requirements A modular animal must: 1. Be mobile. 2. Be heterotrophic--whether vegetarian or carnivorous doesn't really matter. 3. Be constructed largely out of repeatable, interchangeable, and redundant organ complexes, such that damage and regrowth is both possible and expected. 4. Have its detailed large-scale shape determined in large part by environment and injury history, not fixed by genetics. And for the sake of narrowing the scope: 5. Live on land. 6. Exist in a size range typical of mammals--say, somewhere between a housecat and an elephant. This does not, however, necessarily mean that a modular animal can't have critical specialized organ systems, like a single head or single digestive tract; after all, separate the crown of a tree from its roots, and it will die (unless each separate part is in good conditions to regenerate the missing half, of course)--each part may be modular, but that doesn't mean the different parts are arbitrarily divisible. A list of all Anatomically Correct questions can be found here: [Anatomically Correct series.](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798) [Answer] Oops, someone did that (sorta) I’d like to introduce the siphonophore, a colony organism made of specialised individuals called polyps (or sometimes zooids). Examples include the long strings of polyps. [![enter image description here](https://i.stack.imgur.com/XwTXh.jpg)](https://i.stack.imgur.com/XwTXh.jpg) The hideous mass of many different polyps.[![enter image description here](https://i.stack.imgur.com/IRnMI.jpg)](https://i.stack.imgur.com/IRnMI.jpg) Or perhaps the more familiar, blue bottle jellyfish.[![enter image description here](https://i.stack.imgur.com/r7inU.jpg)](https://i.stack.imgur.com/r7inU.jpg) But it isn’t a jellyfish, it’s just related. The sail is an individual organism, and so are each cluster of stinging tentacles, the feeding polyps, and reproductive polyps. Each individual serves one purpose and is utterly useless on its own, having to rely on the other polyps to perform the actions it lacks. This concept can easily be blown up into more complex (and less gelatinous) colonies. In fact, a certain future biology documentary has explored this a little (<https://speculativeevolution.fandom.com/wiki/Ocean_phantom>). The problem of living on land means you may need ‘lung polyps’ ‘locomotive polyps’ and ‘gut polyps’ but otherwise vascular connections and more solid construction may not be too far-fetched. The other option is simply to make them small (I understand this doesn't meet one of your checkpoints). Gas exchange isn’t an issue for insects and frogs. @Chickensarenotcows mentioned planaria, which have an advantage similar to some worms where they can be completely bifurcated and, as long as a certain portion of the body is left intact, completely regenerate. The way this is achieved in siphonophores and partly in planaria is segmentation - basically modularization of the body. Examples of similarly segmented life (without the regenerative ability of course) are centipedes and worms. A merging of these more complex, terrestrial body plans with the colony zooids/polyps of siphonphores could yield a believable organism of your description (if arthropleura is anything of an example). P.S. Sorry for the enthusiasm, I just really like these guys. [Answer] The problem is that plants were able to evolve the way they did because if you cut them, the only criteria the new limb needs is that it has access to sunlight. This makes the random developmental generation of new material without strong negative consequences. Doing this for an animal, which requires locomotion, would be extremely difficult. That's why animals like lizards regenerate limbs, but they follow a very specific structure that allows them to walk the same way every time it happens. If they generated a random limb, varying is size and shape, it would make walking very difficult and they would die off very quickly after that. Hence, not very appropriate for evolution. I propose an entirely new kind of animal with a unique organ or a section of the brain completely devoted to calculating how to use and adapt to its randomly generated limbs. This would allow that animal to have random locomotion patterns, causing each individual of the species to be very difficult to track by predators and thus would benefit the evolution of the species. Some locomotion patterns would be more helpful than others, and as such those patterns would over time be removed from the rules that the generation of new limbs would follow. (ie having limbs of vastly different lengths would be avoided) This animal would be similar to insects, in the sense that they would not have a circulatory system, because loss of blood could cause death and would inhibit the generation of appendages. Rather, upon losing a section of the body, the animal might go into a hibernation stage dedicated to generating new limbs and training the brain how to use those limbs. --- Summary of why my model works: ``` 1. Be mobile ``` My model moves using randomly generated limbs. ``` 2. Be heterotrophic--whether vegetarian or carnivorous doesn't really matter. ``` My model works for all kinds of animals, regardless of diet. ``` 3. Be constructed largely out of repeatable, interchangeable, and redundant organ complexes, such that damage and regrowth is both possible and expected. ``` Other than a lack of circulatory system and a unique organ or dedicated area of the brain, my model does not specify any organs that cannot be regrown. ``` 4. Have its detailed large-scale shape determined in large part by environment and injury history, not fixed by genetics. ``` My model supports its evolutionary development, as well as the ability to generate limbs in a way that can adapt to the environment. For example, developing limbs suitable for climbing, limbs for running, or a combination of both and any other possible uses. ``` 5. Live on land. ``` My model can be land-based, water-based, or flight-based. ``` 6. Exist in a size range typical of mammals--say, somewhere between a housecat and an elephant. ``` No size restrictions need to be placed on my model. However, the larger the animal, the longer the amount of time limb regeneration would require (leaving the animal vulnerable), which suggests that evolution would tend to lean towards developing the species into smaller creatures. [Answer] I think the comments about Echinoderms are actually a good start to get on the right track. It is already the phylum most closely related to the phylum Chordata (which includes mammals), and many of them have similar, if not exact, traits you are describing. 1. Be mobile. No question there. Many species of Echinoderms are mobile, if slow. 2. Be heterotrophic. Again, no issues there, Echinoderms definitely eat stuff. 3. Be constructed such that damage and regrowth is both possible and expected. A notoriously important characteristic of many of the most commonly recognizable Echinoderms. 4. Have its detailed large-scale shape determined in large part by environment and injury history, not fixed by genetics. Here is where we start to diverge from known Echinoderms, and have to borrow from other forms of life. I see 2 main options here, depending on just how mobile the animal is, and just how specialized it's different organ structures are. Option 1: it is very slow moving, and rarely moves when it can avoid it. It remains in place, foraging any food source in the area immediately within its reach, and stays put until the local food source is entirely exhausted. Whenever possible, it grows toward food it can detect, rather than moving toward it. Its appendages for eating and for locomotion are both very small, very numerous, and interconnected (it eats any food it steps on through its feet). When remaining in its current location is not possible, it uses starfish type locomotion (possibly in conjunction with snail/slug type locomotion) to move to a new food source, and repeats the process. Size/shape of the individual is determined by the shape of the food sources it encounters, as it (at least somewhat) grows in to the shape of that source while it feeds. Option 2: Slightly faster moving, but still slow. A generally rounded or spherical shape, but with no set numbers of appendages. I imagine something the shape of a sea-urchin, with a random number of spines. More specialized locomotion appendages are present, but other appendages can be recruited for locomotion for faster movement in emergencies. Existing appendages are converted, or new ones grown, as needed, after injury or accident. The key being "as needed". If a missing limb isn't slowing the animal down, or keeping it from feeding normally, etc, no need to regrow it at all. If repeat attacks occur, defensive appendages could be converted to locomotion "permanently", or vice versa, depending on the types of attacks and the results. 5. Live on land. Sea Cucumbers already have a similar external body plan to slugs, and starfish can reach rocks at high tide that are out of the water at lower tides, and stay there until the tide returns, so there is some (little) precedent for out of water (if not fully land based) animals with some of these characteristics. 6. Size range somewhere between a housecat and an elephant. Sunflower sea stars can get about 4 feet across from arm tip to arm tip (eye-balling some google images, it looks to me like just the body, without the arms, is close to 2 feet across), and sea cucumbers can get more than 6 feet long As far as evolution, it seems to me to be no great leap from tide pools to fully land-based lifestyle, both to evade predators in the tide pools themselves, as well as reach land-based food sources that tide-pool-locked species can't reach, especially if those food sources are similar enough to require relatively small change in digestive function. The first step would probably be water retention, to avoid dehydration on land, followed by specializations for respiratory functions, and then locomotion and food source specialization would be next. [Answer] We are already modular, already mobile, just in a different scale Animals have long had self-repair mechanisms to accommodate loss of cells through either attack/cell death, injury (such as lacerations) or bone fracturing. It is actually in fact also a simple extension of our growth. As we grow, our cells divide and organs grow. When we are embryos, we do not have all organs yet, but as we slowly accumulate more cells they create more organs as dictated by our DNA. In fact, analysis of foetal growth is basically a story of how we evolved. There is a reason why we look so 'tadpole' when we are young, yet as we grow more and more features are added. So what you need is a way for cells to divide and add new organs to replace ones that are lost (perhaps entire new organs) - at a much more drastic, foolproof rate that we do now. This will be difficult but not impossible. * We need to ensure continuous function, such that absent organs are not missed. We therefore need redundancy in major organs, so we may need more kidneys, hearts and other organs in different areas to provide this redundancy. Such evolution would be a difficult leap, but not unheard of. * We need the ability for growth to be following a new pattern, in a way which retains functionality. So if our arm is removed, we need to grow nerves, bone, muscle and skin in the same way we grow them as an embryo. This would require coordination of regeneration in a much more smart way than we do currently, but again should be feasible. * We need a pathway in evolution to achieve this. Evolution is driven by both necessity and sexuality. To accomplish your objectives in your question, there needs to be both a physical need to grow this way, and a psychological desire to do so by your mate. Anything goes, but I think it would be possible to find a route there if these hold true. [Answer] I am not entirely Clear on what your question is. I imagine you are asking whether an organism can develop or evolve in such a way that it has the internal systems of a Plant (regeneration and such) as well as the higher functions of animals (locomotion, thought). i.e. something like Dc’s [Swamp thing](https://en.wikipedia.org/wiki/Swamp_Thing). This is most likely going to turn into a Biology lecture. And I will be making some conjecture where my expertise is lacking. But, here are my thoughts. ## An Organism Capable of locomotion and some manner of self-awareness, does so at sacrifice of other traits, including a modular cell nature. As far as I am aware. Let me Explain. In RPG terms, i think the biggest challenge for such an organism would be the trade off between High Physical Stats and Processing power. The modular structure of the plants enables them to grow to sizes unattainable by most animals. It facilitates damage reduction and high regeneration such that they can recover being cut down provided the right conditions are met. But this comes at a cost of lack of cognition. Any animal no matter how small, has a sense of self. They are aware of their own body and have at least the most rudimentary instincts. Even a cockroach or an earth worm has self-preservation instinct. While there are some plants with similar defensive characters, they are more trigger based than instincts. (E.g. Tactile/Odor based irritants & allergens) The plant body has no centralized structure. Which means any plant cell taken from the whole can perform all the functions of the whole. And this range of functions while impressive are limited in the scope of terms. In Biochemical terms, a cell can perform only so many reactions at a time. Or an interval. If it needs to do more, add more, it must sacrifice some other to make space. It needs more [Processing power](https://en.wikipedia.org/wiki/Biological_computing). Take this scaled up Macro analogy. Whales were once terrestrial mammals. In time they evolved to be aquatic organisms. And concurrently their physiology adapted to suit their new evolutionary path. Their forelimbs flattened and became flaps, the hind limbs relatively unnecessary for swimming, regressed completely and is now just a vestigial bone making their bodies more streamlined. And the freed up energy, previously spent to development of limbs was re purposed for better respiratory capabilities and lungs that can withstand the strong pressures in the deep waters. Similarly, in the procession leading from Cell based life forms to Kingdom Animalia, the cells instead of doing everything by itself started to delegate and compartmentalize tasks. In Multi cellular organisms Cells began to [Differentiate](https://en.wikipedia.org/wiki/Cellular_differentiation) to accommodate specialized tasks. These specialized cells could do only a fraction of what the originals could. But now instead of a single cell performing n number of tasks, there were x types of cells each performing n/x number of different processes. (An oversimplification. Differentiation in actual physiological systems rarely follow set division of labor) The remainder of the cell’s available biochemical potential, i.e. its Processing Power could be allotted to new tasks. And believe me you, the capability of self-propelled motion is a game changer. Now, the energy sources available to you are as large as the expanse you can cover on your own. This albeit means that you’ve sacrificed the capability to utilize some of the micro nutrients and minerals. With Locomotion comes more specialization. Because remember, now you are actively interacting with your environment as opposed to be molded by it. And each specialization develops it own sub-specialization. All this necessitates the need for a centralized control scheme. Because the old way of moving by ‘sensing’ the higher concentration of nutrients is not always viable over the now (relatively) large distances. Which necessitates more processing power, which needs more energy and more specialization. And so, we ascend further in the ladder of complexity. And Specialization is the death of Flexibility. In the current scheme of complex organisms all cells in the body have, in theory, the capability to perform all necessary physiological functions. But not at the same time. These progenitors, (Stem cells) become differentiated to serve their assigned role as early as day 5 of development. (Note that we’ve shifted from talking about Asexual cloning methods, to gene mixing in form of sexual fertilization). From then on, until the death of that organism individual groups of cells performs only the function assigned to them. And as mentioned before, this system is so welded in place that such groups of cells are virtually irreplaceable. Except the Brain. Which is ‘literally’ Irreplaceable. The Brain, one of the crown Jewels of the Animal Kingdom, and the greatest energy sink in the body (20 percent of total available) is so vital, stopping its function for more than a couple minutes would end that organism’s existence. Even when all other organs are working perfectly. And it’s so individualistic replacing it with a spare is, let’s say is NOT the preferred fix. The condition called [Brain death](https://en.wikipedia.org/wiki/Brain_death) results in a body which in theory is in working condition; and hence one of the reasons that victims of brain death are treasure troves for multiple organ replacements. To Summarize: The very reason that you are ‘aware’ of your existence means you’ve given up the chance for the unbelievably broken ability to regenerate from the smallest of parts. While the lack of ‘awareness’ plants and other cellular entities capable of such feats are not in a position to, let’s say ‘appreciate’ it. Back to the game analogy. You are a mage that sacrificed physical vitality to gain intelligence for casting spells. While the other side is a passive Berserker/Tank that gained near infinite regenerative capabilities but are nothing more than collected mass. (Implying plants are dumb, is an incorrect and highly inaccurate statement. And in some circles, intelligence is not measured in same standards to plants as they are to animals. But you get the idea.) P.S. I’m aware that some parts of my answer have run far, far off tracks. But if I was able to assist it in any ways I’ll feel satisfied. As was this a good thought piece for me. [Answer] A modular animal could be similar to an lizard in overall shape, but with the legs and tail branching out modularly like a plant. This creature would also have to be herbivorous, have extremely good predator defences, and have very little competion, as these traits would mean that they never need to move quickly, and reducing the selective pressure to become more standardized Another way modular animals could evolve is if a sessile modular animal, due to an extinction event or something similar, ended up as the only moving organism in their area, which would likely lead to them evolving to become motile again [Answer] Interestingly enough, afaik your chosen terminology for the question might've been de-railing. "Plant-likes" are more similar to a [Reaction-Diffusion System](https://en.wikipedia.org/wiki/Reaction%E2%80%93diffusion_system) than modular Legos (it's how leaves, roots, [stomata](https://en.wikipedia.org/wiki/Stoma), etc. are "located" and then grown). "Blob-likes" even more so. Whereas "Fixed-likes" are more like modular Legos, where each has been pruned down to the bare minimum and essential arrangement. By necessity your looking somewhere on the spectrum of Chemical Soup for a single organism: from Chaos (a la [Calico Spots](https://en.wikipedia.org/wiki/Calico_cat)) to Order (a la [Colonies](https://en.wikipedia.org/wiki/Coral)) with as little specialization as possible. Injecting modular specialization Legos here and there adds spice to the creature but also weakness, unless it's a redundant or "omnipotent" piece. In which case you're leaning more towards Order anyways. A cat for example has many Legos: specialized cells modularized into skin, hair, and other pieces. If you averaged cells' competencies and merged them into a couple few cells to increase redundancy; you'd have very little structure left besides diffusion-reaction, [diffusion-aggregate](https://en.wikipedia.org/wiki/Diffusion-limited_aggregation), or [crystalline](https://en.wikipedia.org/wiki/Crystal#Occurrence_in_nature) so your body plans would be limited. A knee for example requires too much coordination, imagine growing any plant and hoping it formed vague muscle shapes and separate branches coming together in a socket-like shape! Even the absolute squinty-eyed rudest approximation would be sensational. On the other hand......... Your best bet for what you want is probably (as has been mentioned): Symbiosis Just make a bunch of little interchangeable symbiotic creatures. This one does thinking, this one does acid, if they're essentially "specialized cells" but can survive alone, just better together... You've got a modular creature with very few constraints! (And as @XenoDwarf's answer pointed out: they don't even necessarily need to be able to survive solo. But that limits you a little bit, even if you gain some efficiency) You've probably got a higher caloric requirement with symbiosis, which if you're familiar with integration or inlining in any of various of contexts (programming, economics, etc.) will probably be pretty easy to see. But other than that issue it's probably the best fit! [Answer] A tapeworm fits your description. [![enter image description here](https://i.stack.imgur.com/OvUoN.jpg)](https://i.stack.imgur.com/OvUoN.jpg) Tapeworms are intestinal parasites of land and water vertebrates. A tapeworm has no mouth, intestine, excretory organs or respiratory organs. The worm's body consists of the scolex, which is an organ it uses to attach itself to the inside of the hosts intestine. After that it is repeated segments which are your modules. Each of these segments (proglottids) contains sex organs with which it can reproduce. The entire worm comprised of many modular segments can move about in the host's intestine. Proglottid segments are motile too. Each proglottid segment can break off and form a new worm. A worm will have only one scolex, I think. Unless it breaks in half in which case the one without the scolex will grow one. The worm is simple and that is how it can get away with this modular plan. As regards a body plan dictated by circumstance and history, in the case of the various tapeworms that adds up to length. Length is determined by how many modular repeats (proglottids) the body is made of. The length of the worm will vary and this is where it meets your last criterion, for size. Your low end is the size of a cat. These worms can grow to be 20 meters long. I assert that is a cat's worth of worm meat. ]
[Question] [ I'm trying to create a planet with a hot desert north and south pole but a cold equator. Is this possible? and if so how? And if it's heavily related to space how would night and day work on this place? I don't want a high fantasy reason, the world having 2 suns, or a network of underground volcanoes that are only heating up the north and south but not the middle. [Answer] ## Have an axis tilt [1] over 56° or under 124° Between these points the poles and the equator switch climate. Technically speaking the poles simply have a higher thermal insolation average per year than the equator. This graphic [5] shows the relationship between axial tilt (obliquity) and the yearly average temperature (insolation) for a given latitude. [![enter image description here](https://serving.photos.photobox.com/04310456df457eef80159b2a472a345dd561951a201bcf2fa68de84e7d081451ac47ac24.jpg)](https://serving.photos.photobox.com/04310456df457eef80159b2a472a345dd561951a201bcf2fa68de84e7d081451ac47ac24.jpg) Looking at the graphs having an axial tilt near the limits won't give you polar deserts (actually the poles would be tropical with a ring of deserts around them, but some tweaking could reduce the rainforest to desert) and equatorial ice capes, but overall global moderate average temperatures. At 90° axial tilt, the poles have the warmest average temperature and the equator the coldest. Yet keep in mind that I'm talking about yearly averages. An object that is at absolute zero for half a year and at 273 C° for the other averages out to moderate 0 C°. At 90° this illustration isn't far from the fact. If one hemisphere on a 90° world experiences winter it also experiences night. The "night" lasts for 1/4 of the year. Vice versa for the other hemisphere and summer. Autumn and spring will be moderate-ish. The equator will be the coldest place on such a planet, but as the graph shows not nearly as cold as Earth's poles. I'm uncertain if permanent icecaps are possible and while they aren't out of the question a tundra belt seems more plausible in most cases. The seasons in the region will be two "twilight" seasons in winter and summer and "rotation day" seasons in autumn and spring. The poles will be deserts in the sense of desolate wastelands, swinging between the hottest and coldest points on the planet on a half-yearly basis. The intermediate seasons will be slightly more moderate, but the temperature difference will purge anything staying longer than these seasons. How extreme the temperature differences will depend on whether or not the circulation cells in the atmosphere and the rotational forces creating them are stronger than the winds thermal pressures, which will try to redistribute warm air equally across the surface. This is what happens on tidally locked planets where similar temperature differences can be found according to the latest simulations. I wasn't able to find any material on this case so choose whatever fits your needs. ## Conclusion Changing axial tilt is by far the easiest way to achieve your goal. My recommendation would be to place the planet near the outer edge if the habitable zone to make the equator as cold as possible, raising the plausibility of an ice shield surviving the intermediate seasons. The poles will still be deserts going from frying to freezing, but that's a cool extra. Axial tilt wise I would stick close to 90°, keeping the equator as cold as possible and making the seasonal cycle simple. While nothing short of a climate simulation will give you the full picture, this video [2] might help. For further reading, I would recommend this paper [3] on versions of Earth with different axial tilt. [1] <https://en.m.wikipedia.org/wiki/Axial_tilt> [2] <https://youtu.be/J4K3H9aNLpE> [3] <https://www.youtube.com/redirect?event=video_description&html_redirect=1&redir_token=3JAkHxRedLFbHxzvUdN1gVlo-1p8MTU1NjYxOTY0MUAxNTU2NTMzMjQx&q=http%3A%2F%2Fgoo.gl%2FQGA6Ga&v=J4K3H9aNLpE> (Pdf) [5] <https://m.imgur.com/yJHPwd7> [Answer] Starting with the Earth as a template: * Move it closer to the sun * Reduce axial tilt * Add thick rings Rings around a planet like Earth would last a few million years at best, but we've been around for less time than that. The poles would be hot due to star proximity. The rings would reduce radiation on and close to the equator, making it cold. [Answer] Some expansion on this comment: > > Slap a thick enough atmosphere on your planet (earth + 25% at least) and create Tibetian-like highlands all around your equator, while eliminating axial tilt to create moderate climate. Plus, huge continents around the poles with next to no precipitation. > > > --- 1. Remove axial tilt - Why? Because this removes most of the seasonal changes, especially the long polar nights during winters, thus increasing the average temperature at the poles at least a bit. This should counter the effect of low solar irradiance a bit and prevent the forming of ice caps. 2. Add huge continents at the poles - Why? The interior of continents tends to have a harsher, drier climate, aka continental climate. Take a look at the Gobi desert. Dry, sometimes hot, sometimes freezing - located at the heart of the Asian contintent. Antarctica is another example. - You will get Gobi-like deserts, but not Sahara-like. Dry and inhospitable, but not scorching hot throughout the year. 3. Tibetian highlands - Why? The Himalaya and Tibet directly to its north are about the same latitude as Cairo or Florida. Though not directly polar, the great altitude creates polarlike conditions with permafrost, glaciers and lots of snow. For good measure, add another 1000 m of height, as to why: see below. Also huge mountains make good places for lush hidden valleys full of wise men, mystical artifacts and/or fountains of youth. 4. Make the atmosphere thicker/higher - and warmer - Why? The atmosphere needs to be a bit warmer than our Earth's, in order to prevent the poles from freezing all year round. About 5°C should do the trick, maybe less. Hard to answer without a climate model. When you make the planet warmer, your highlands need to be higher up in order to have the desired climate, and in order to be still hospitable/traversable you need more atmosphere. Add about 2 km in thickness for good measure. --- So,this should get you the sketched conditions. You will not have real ice caps at the equator, stretching over hundreds of miles, but rather huge mountains, peaking through glaciers which flow around them and bury the highlands to some extent. You will not have Sahara-like, scorching hot deserts at the poles. This is not really possible. Still, temperatures could change by 30 to 40°C during one day, and it will be really dry. --- Possible problems your world could encounter: * You put a giant ring of rock in the equator. This might mess up the climate. The flanks of said ring should be lush jungles, since winds from the north and south will push moist air up the flanks. Just like in northern India. Exchange of air across the euqator is limited, which could prove a problem - or a story-element (think jet-like winds rushing through the few passes leading across the Wall). * You put huge continents at the poles. This will mess up your climate. Also your ocean currents are hellish, if you stick to circular oceans. Same would go for wind currents (take a look at the Screaming Sixties) engulfing Antarctica. * If you don't leave enough room for oceans, your world would be about as dry as the planet Dune. If you limit your continents to the described three, travel between them would be rather scarce. --- Okay, I tried to make it as short as possible and to not get lost in detail. Still, I feel I could expand on some issues, don't hesitate to ask. [Answer] If you don't insist that your polar desert be hot, look no further than Earth. The South Polar Plateau in Antarctica is one of the most arid landmasses on Earth, with annual precipitation of about 7 cm of snow (convert that to liquid, and that's drier than the Atacama Desert in Chile and Peru). The northern ice cap is similarly arid, though it's harder to notice with the sea ice (formed by surface freezing of sea water, for the most part). Move the Earth a couple million miles further from the sun, and the poles will get even drier (less water evaporating from the oceans). [Answer] Physics is not your friend here, the equator gets more sunlight coming in at a more vertical angle and passing through less atmosphere. This means higher temperatures. The one thing that does counteract that is altitude, so the solution to your problem is to have a very high plateau or mountain range that happens to run roughly around the equator of the planet. Just think of the Himalayas for example which are at the same latitude as Egypt and India and yet have permanent snow cover. It would be an odd coincidence to have it run like that and continental drift over millions or billions of years would change things but for several million years you could have a mostly cold equator with maybe occasional warmer valleys where the altitude drops and obviously if you had any coasts or oceans they would be tropical. [Answer] Step 1: Move your planet further from the local star. This reduces the temperature, and freezes the equator Step 2: Situate large volcanos, geysers and similar geological activity at the North and South poles. These provides heat for your deserts [Answer] While it is improbable that a planet like this would exist given that we have not yet observed one in our universe. Having the planet's axis of rotation be a line tangent to it's orbital path would move your equator to be a band that would run through where the poles are on Earth while the new poles would be on the right and left sides of the planet. [Answer] It is possible that the correct design for a habitable Earth-sized exomoon orbiting a gas giant planet in the habitable zone of their star might help with making this possible. You should look up previous questions and answers about possibly habitable exomoons of gas giant planets. One thing which they say is that for the orbit of a moon around its planet to be stable long term the orbit of the planet around its star has to last at least nine times as long as the orbit of the moon around its planet. So if the orbit of the moon around its planet lasts 10 Earth days, the orbit of the planet around its star would have to be at least 90 Earth days long. And if the planet's orbit around the star is not much more than nine times as long as the moon's orbit around the planet, the combination of them might keep parts of the moon in sunlight or in the shadow of the planet for longer periods of time and thus cause those parts of the moon to heat up or cool down more. Remember that the earth sized moon will be tidally locked so that it will rotate with the same period as it orbits around the planet. Thus there will be a planetward side of the habitable moon that will always face the planet, and an antiplanetward side of the moon that will always face away from the planet. The shape of the shadow of the planet will depend on the values of the diameter of the star, the diameter of the planet, and distance between the star and the planet.The umbra, the totally dark part of the shadow, should be a cone that gets thinner and thinner with distance from the planet and comes to a point, while the penumbra, the partially dark part of the shadow, should be a cone that spreads out with distance from the planet, and extends out into space forever. When the moon is in the penumbra the reduced light from the star may be enough to make water in the colder parts of the moon, such as in a hypothetical high equatorial ridge around the moon, freeze. And possibly if the sizeof the umbra at the distance of the moon is just right, only the equatorial ridge regions will ever been in total darkness and get even colder whenever the moon enters the umbra. You might try modelling two different designs of the star/planet/moon system to see which gives the hottest poles and the coldest equator. In both models the moon will orbit around the equator of the gas giant planet and the moon's own equatorial plane will be in the same plane as it orbits the gas giant planet, because tidal interactions between the moon and the planet will alter the moon's orbit and rotation into that configuration billions of years before the moon has a breathable atmosphere or advanced multi celled lifeforms such a intelligent beings evolve on that moon. In one model the orbit of the moon around the gas giant planet should be in the same plane as the orbit of the gas giant planet around the star. In the other model the orbit of the moon around the gas giant planet should be in a very different plane - titled about 90 degrees, similar to the axial tilt of Uranus - from the orbit of the gas giant planet around the star. My answer here [Polar Heat, Equatorial Cold - Climatic Effects of Inverted Global Temperatures](https://worldbuilding.stackexchange.com/questions/75580/polar-heat-equatorial-cold-climatic-effects-of-inverted-global-temperatures/76344#76344)[1](https://worldbuilding.stackexchange.com/questions/75580/polar-heat-equatorial-cold-climatic-effects-of-inverted-global-temperatures/76344#76344) discusses how the second model would affect the climate and possibly result in cold equator and hot poles. There have been many questions about possible Earth sized habitable moons of gas giant planets. I have answered a number of those questions. Here is a link to a previous question and my answer to that question includes a link to a question and answer which has links to previous questions and answers. [What are the day and night fluctuations for a moon orbiting a planet the size of Jupiter?](https://worldbuilding.stackexchange.com/questions/137322/what-are-the-day-and-night-fluctuations-for-a-moon-orbiting-a-planet-the-size-of/137368#137368)[2](http://What%20are%20the%20day%20and%20night%20fluctuations%20for%20a%20moon%20orbiting%20a%20planet%20the%20size%20of%20Jupiter?) The article "Exomoon Habitability Constrained by Illumination and Tidal heating" by Rene Heller and Roy Barnes Astrobiology, January 2013, discusses factors affecting the habitability of exomoons. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/>[3](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/) Also see my answer here: [How long will it take to discover they live on a moon and not on a planet?](https://worldbuilding.stackexchange.com/questions/125617/how-long-will-it-take-to-discover-they-live-on-a-moon-and-not-on-a-planet/125653#125653)[4](https://worldbuilding.stackexchange.com/questions/125617/how-long-will-it-take-to-discover-they-live-on-a-moon-and-not-on-a-planet/125653#125653) ]
[Question] [ I remember watching a documentary some time ago and at one point they were talking about how empires were limited to a certain size since there was no way to communicate across the empire quickly and reliably. The best method they had was courier by horse and that had a limited range. Also empires in America would have an even smaller max size since they had no horses and had to communicate sending people running from courier post to courier post. Transport by sea doesn't really help; colonial empires did control vast areas so far apart, but they did't get much inland control. I imagine sea then horse would cause a lot of different problems. So with today's reliable and fast communication could an empire rule over the whole planet? (Taking in consideration only this fact about communication) [Answer] Yes... and no... Is today's communication fast enough and capable enough to manage a planetary empire? Absolutely. The Internet alone could do it. That's not your problem. Let me suggest a [frame challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609): Your problem is establishing such an empire in a believable way, because the technology that allows massive, instantaneous communication also allows for considerable freedoms involving transportation, weaponry, housing, and (not surprisingly) communication against the empire. When you consider the various near-worldwide colonial/empire periods of Earth, you discover that people were (relatively) easily controlled because the conqueror had tremendous advantage in firepower and manpower. Genghis Khan was attacking, predominantly, villages that were loosely organized at best. England, Spain, and the Netherlands brought overwhelming firepower and organization to bear against the many lands they conquered and controlled. The same can be said about the U.S. westward expansion. You don't have that advantage today. It seems like you do. You have tanks and planes and aircraft carriers — and they're all very impressive — but while you may logistically control the entire planet, you would be constantly fighting rebellions and resistances. Well-armed rebellions and resistances. And history has proven that they could fight against tanks, etc. in the past. Technology is a great equalizer (well... for bad, if not for good). Consider the various difficulties in Africa today — difficulties made simple because arming yourself with automatic weaponry that can eliminate whole villages in minutes is trivial. Why can't the villages do the same? They're poor. Which is probably the only way a planetary empire could stay in control — poverty. But then, what's the point of the empire? [Answer] Yes. Many large corporations and organizations already operate on a global scale just fine. Just add some local and regional governments such as nearly all governments already do and you have a functioning global empire. It is unlikely to happen with a democratic government without an alien invasion or some other reason to have world government but a fascist or communist government might go for world domination. Their legitimacy comes from a unifying ideology and works just as well (or badly) for a planet as it does for a single commune. A theocratic government would also work. An Islamic caliphate for example would actually have perfectly valid reasons to seek to unite the world under its power. A Christian or Hindu version of the same would work just fine. And manufacturing a reason for a democratic government to go for it isn't really that hard. Any kind of global event that threatens the extinction or subjugation of entire human species would work. Or people could just get really tired of pointless wars. The European Union largely exists because [people figured that an economic union between France and Germany really would save lots of bother](https://en.wikipedia.org/wiki/European_Coal_and_Steel_Community). EDIT: Since I started by pointing out that corporations work on a global scale, I probably should mention that it has required some adaptations to how they operate. This is because the "working hours" happen at different times in different parts of the world. Typically (a simplified general model) you'd split the world into three operational zones (24/8 = 3) and have active operational control cycle between these. Typically these are the Americas, Europe and Africa (or [EMEA](https://en.wikipedia.org/wiki/Europe,_the_Middle_East_and_Africa)), and Asia and Oceania. A global empire would probably copy this solution and essentially have three administrative centers. Say, Washington, Brussels, and Beijing. Depends on how the empire came to be. The central government could be in one of these or cycle between them or even be divided between the three. The EU has split its functions between multiple locations for political reasons and it kind of works with fast travel and telecommunications. [Answer] Yes. I'll break it into two parts, communication relating to Empire Citizens, and Communications within the powers that be. My first thoughts go to China and their citizen points system being worked into place. The first step would be to pull as many people into the cities as possible, having most of your population in sight of you cameras and tracking technology would be crucial. Monitoring any internet/ media usage of a population is a common occurrence today, and would be extended to make sure nobody is forming a group to go against your reign. We have the technology to track the whereabouts of every citizen, so we would be able to tell who is meeting up with who, where people are going and what they are doing. With no privacy, people cannot create a revolution. Communication between generals, media controllers, the world leader, and everyone else is instant. People are able to make a snap decision and have millions of people respond and react to it, I don't see why that couldn't be scaled up to billions. For example if a curfew was implemented suddenly, the police/ military could immediately respond to the situation without having to take the step of waiting for a courier. Most of these solutions are dystopic, but I think world government and control over the whole planet causes those situations to arise. You would need to squash all attempts at disruption, and you would be able to do so quickly. [Answer] # Yes The limitation you provide has been overcome for centuries. The British Empire was globe-spanning, and could keep itself together, project force, deal with insurrections, etc. It had sigificant ability to project force inland -- British India is not a coastal nation. It even fought wars in Afghanistan, one of the least navaly-accessible regions of the world. More recently, both the American and Russian empires where globe spanning. Both ruled through proxy or puppet states, with the Russians being a bit more heavy handed. The Russian empire crossed Asia, and included states in the Middle East and Cuba. It even fought wars in SE Asia; the logistics of having a semi-hostile China between it and the region, and American naval dominance, was more of a problem than communication delay. The American empire included naval and military bases scattered over the world (which still exist), and "allied" puppet democracies, dictatorships, and kingdoms. They had allied empires (the old European ones), and could project force around the world in response to insurrection (such as Vietnam, an insurrection against the old French empire). The 3 large Empires left -- America, the fragments of the cold war Russian, and the Chinese -- have different approaches. The Russian Empire is at this point honestly too weak to project force much outside its borders. The Chinese and American are mostly trade-based empires. Chinese conquest of Tibet/Mongolia and the South China Sea, and its threatened conquest of Taiwan, are relatively local geopolitical concerns; it lacks the ability to reliably project force past an American naval screen. It may or may not become more openly imperial as its economic and military strength grows. American's traditional approach has been to use trade to expand its imperial influence. So long as you allow US companies in to reap profits, it leaves you alone. If you do go protectionist and you are relatively small and you align with regional or global foes and there is something the US could profit from in your territory, you are basically placed on a "oh well" list, and the next time an American president needs a poll boost they start talking about an "axis of evil" or whatever excuse and replace your government. [Answer] Yes... but empires are not only about technology Restricting the answer to your question, then yes, technology today is more than enough to overcome the problems that plagued empires of the past. But the ability of controlling and projecting military force through your empire is but one of the factors sustaining it. Not even empires could force people to work for them at sword/gun point, and more often than not it consisted of conquered peoples who were mostly to govern themselves except for a few questions (recognition of the empire's sovereignty, taxes, conscription...) for the profit of the empire. Additionally, often the empires bought the support from some part of the population by offering some advanteges. Kings can get support from the empire if someone challenges their rule, nobility get protection from uprisings from peasants, traders access to trade routes, minorities (religious, etc.) some sort of protection... TL/DR The technological angle is currently enough to support a global empire, but it is not sufficient by itself. [Answer] First of all, although it might be possible for a single empire to control the whole or most of the planet, it is more likely that there will be at least 2 superpowers, together controlling most or all of the world, but being separate and either opposing eachother or being neutral until an opportunity arrives. Realistically, you would have 3-6 empires, though alliances would make them feel like 2-3. So even if you had a single empire, it is likely that sooner or later it will break up into a few pieces. As long as the pieces are allied or neutral, all is good, but if the pieces are active enemies, there is a chance for further splitting into smaller parts. Now, if the empire is somehow spanning multiple planets, like if portals/wormholes are present to connect the two, or the gravity is weak enough for space-towers to connect the two, then it might be easier to have a planet-wide empire. This is the bare minimum needed for an empire to control the whole planet: Optical telegraph, trains, mirror-based telescope, masts, airplane wings, fans (of any kind) and hot air balloons (to mix them to get an airship), and reduction gears. Extra points for steam engines, stirling engines and windmills, waterwheels and aerial ropeways. * The optical telegraphs are used to send and receive messages. * Mirror-based telescopes are used to check on other nearby settlements, to see if -something is wrong, and for mapping. * Airships powered by pedals or treadles for mapping and traveling without having to use roads, or to change from carts to ships and back. Reduction gears would be used for moving the fans at the wanted speed. + Trains powered by pedals/treadles/hamster\_wheels and using human or animal power to move, and aerial ropeways to help it move uphill or accelerate faster when leaving the station. Reduction gears would be used for moving the wheels at the wanted speed. * Steam engines for ships and airships (not necessary airplanes), for when the masts are not delivering enough power, or when you would rather hurry. * Stirling engines are for mechanical power generation, and for refrigeration if you run them in reverse, feeding them movement and moving heat instead of feeding them temperature difference and receiving movement. Using tall towers for the optical telegraphs, you can increase the distance you can talk with both fixed and moving targets. Usually, the fixed targets will be talked with by using strong lights and mirrors to blink/flash towards the target, and the target will use a telescope to look at you and see the signal. For that reason, it is likely that different towers or different coordinates will be used, often with some space nearby to make sure the target is not thinking you sent a message when in fact it was a different tower. The optical telegraphs would be first used for mapping, and next would be using airships for mapping. Due to the danger of airborne attacks, the medieval castles will evolve to oversized ziggurat cities, with mirrors sending a lot of sunlight to the underground, since using torches would be rather dangerous. With airships, you can get a better picture of the continents, also useful for maps, and also travel for long distances without worrying about mountains and water currents, but instead worrying about wind currents. We had bearings, both plain and roller and ball bearings since around the time Roma was born. There were also trains used for a short time period around that time, too. Even without steam and stirling engines, just with wind power, water power and pedaling, we can have an empire span the whole globe. The trains would be used for moving things on a long distance using windmills, waterwheels and pedals/treadles/hamster\_wheels. Plus that trains would be used to move large quantities of troops and resources to deal with rebellions and other issues. If need be, a pedal-powered fast blimp might be used to deploy some shock troops, or elites, to deal with the problem immediately. Stirling engines can be used instead of steam engines and watermills and windmills for a distributed mechanical power generation network, probably using mechanical tension on ropes to move the power around. Alternative ways to move power would be compressed air, compressed water (tap water) from a water tower (or more water towers) used as storage and compression chambers. The energy can be supplemented with wind power and/or water power, if needed or wanted. That's it. That's all one would need. And that is still a bit much. Edit: You can use pedal/treadle powered vehicles to move faster with either human power or animal power. Just get an animal or human on an oversized hamster wheel (like those thread wheels used in medieval times to move heavy things up in elevation), and you can use their output to achieve high speeds. With or without rails. During the US's Great Depression, people tried using pedal-powered cars, but shortly after that there was a lowering in fuel price, which caused the idea to be abandoned by most people. There is a lot more which can be done with that, so ask me if you want to know more. Edit 2: It would also be useful to have a technological advantage over the rest of the world, to be able to give important gifts to the taken over people, to win them over and ensure rebellions will not happen. Since papyrus can be made, and wax and resin were used to waterproof things, there can be an empire which uses waterproofed papyrus paper boards for greenhouses, which might be cheaper and require lower tech than glass does, plus that you would use glass for the mirrors needed for the telescopes for the optical telegraph. Greenhouses will also keep your existing people fed and give them cheaper condiments. For growing temperate plants in the desert, you would likely need some way to cool the air, like through pipes going underground for tens of meters, before getting into the greenhouses where the amount of light is limited by having a few small windows allowing a lot less sunlight inside, which paired with the colder air can sustain temperate-climate plants. The humidity would still be an issue, though. Being able to get spices and grow temperate plants in colder and hotter climates surely does make up for that. [Answer] Yes you can. No place on earth is more then 7 days away from the possible power bases of the empire because ships and planes are very fast today. A task force could depart from Shanghai and hit London (and vice-versa) in less then a week. The logistics and the communication infrastructure for such an empire alredy exists. But the real question for the emperor and his minions would be: what now? If you conquer the whole world you have nowhere else to go. Young, aggressive, members of the imperial elite, that, in a lesser empire could be dealt with by sending them to die in campaigns will have nowhere to go. A world empire is a time bomb ticking [Answer] Yes, absolutely. It will be easy to control the entire world, once dominance is established. And rebels will not be as strong as they were, in the past. Yes, rebels do use modern technology at combat, but because the tech today is massively destructive, and the army uses modern means of control, science and logic in reasoning and deducing strategies, it is quite unlikely that any rebel team would succeed at outsmarting the empire. They would be better off working from within the empire to betray the emperor, but that will also be quite risky. Why is that? In the past, people never dynamically employed scientific and logical strategies in combat, as much as we do today. Most kingdoms and empires in the past were taken down by outsmarting the emperor's army. But today, the military has R&D, and thus creates advanced weapons. They have heavily funded teams of brilliant minds who would work towards taking down their enemy. Today, the rebels do not have enough space to hide, as every part of the earth is measured and mapped. Even if they hide, it will not be possible for them to grow big and become dangerous: because they will need a lot of R&D and training, thus must have a well funded team of scientists, strategists and other people skilled in combat. If someone had already managed to become an emperor (which is highly unlikely) it will literally be impossible to take that person down. Because, he will have the best minds on the planet (literally on the planet, as he controls the entire world), and as long as they work for him, and as long as he is in good terms with people who are immediately below his rank, nothing will stop him. There is a new emerging psychology called the cyber-psychology. The same methods used by the game industry and the social networking sites can be used to massively control people. It is possible to psychologically control people by socially reward them for certain task while punishing them for the others. Imagine using a social networking site in a imperial world. If the emperor hates certain kind of topics, it is unimaginable to think that he wouldn't socially punish citizens who engaging in such topics. A simple way to do this is by improving the visibility of their content (which involves their personal profile or anything else they post) among people who would genuinely despise the topic and decrease the visibility of the content among people who may have the same views. Actions like hearts, likes, up-votes or points etc can be used as the incentive here. This could also go further- to jobs and credit scores. Soon, most content in the social network will be in favor of the emperor. And massive surveillance can be used to study people and respond almost spontaneously, to "fix issues". In this situation, there is no room for rebels. For rebels to exist, you need a mob of angry people, not zombies controlled by social networks. Also, even if you have angry people, what chance will they have against heavily funded experts working for the emperor? Thus, I believe today is the right time for someone to be the world's emperor, as he could do more than just "communicate very fast". He could literally condition the psychology of the world to his needs. But it is highly unlikely that someone would grow powerful enough to conquer the world. ]
[Question] [ Warning This question is one of a series about specific use of teleportation. It will concern only about pressure and atmosphere. Here are previous question: * [Teleportation and speed](https://worldbuilding.stackexchange.com/questions/131575/teleportation-keeping-momentum-on-arrival) ## Context The story happens in our world and current era. The protagonist possesses the power of teleportation with the following characteristics: * When teleporting, a volume including the protagonist is swapped with the same volume of matter in another place. For example, if the destination is in open air, the departure will receive the same volume of air. * That result with no problem of collision of matter: if the destination is in a solid rock, the protagonist will arrive in the rock. And at the departure, there will be a volume of rock with the same shape as the protagonist. * There are no collision problems, but there are still problems: the destination can override a part of something since what matters is the volume. It’s not a problem when swapping a part of a rock, but it’s one when swapping a part of a person. * The volume of exchange has the same shape as the protagonist adding a layer around it. The layer is at minima 5cm, but can expand by willpower. * There is no minimum time between two swaps: it can be as short as reflexes permits. * The protagonist can teleport as long as it has willpower: think of it as a superhero power. * The teleportation happens if the protagonist can picture it. Coordinate won’t work, but a memory, a picture/film will (no matter the distance). The protagonist could also teleport in a hidden part, even if what behind is unknown as long as the protagonist can guess it (for example behind a door or a rock). * Both volume exchanged keep their momentum ignoring the difference in velocity of the Earth's rotation. Falling toward Earth on the south pole, and teleporting to the north pole will result in the protagonist still falling. Flying westward and teleporting to facing eastward, will cause the protagonist to shoot forward in the eastward direction at the same speed. * If the destination is a moving structure (vehicle...), the protagonist will teleport at the coordinate where the structure was when teleporting. But the protagonist will keep its momentum, resulting in a possible speed difference. Comparison is like trying to jump in a car in your everiday life: there won't be too much problems if the car is slow or stopped, but there will if you are on foot and the car is at 90km/h. -If the destination is a picture or a memory of a moving structure, the destination will be at the coordinate when the picture/memory took place. ## Question My question here is about the impact of difference of pressure in the air. Here are two examples: * The loved one of the protagonist was captured and brought to the summit of Mt Everest (30kPa). What are the possible risk if the protagonist teleport from the sea level (100kPa)? Can there be prevented ? And what happened of the air brought around the protagonist ? * Due to theological reason, the protagonist have to go back and forth between Jericho (258m under sea level) and Lhasa (3658m above sea level). What are the possible short term and long term effect for such trip ? Is the difference of pressure sufficient for [barotrauma](https://en.wikipedia.org/wiki/Barotrauma) ? Please try to not raise problems from other subject since there will be other questions for them. [Answer] Obviously, the pressure change between any two habitable places is not a problem if you take a week to make the journey. The issue is the suddenness of the pressure change. If the teleportation is literally instantaneous then that might be a problem. As you depart the peak of Everest and materialise at sea level, you are suddenly surrounded by a wall of air at 70kPa above ambient pressure (relative to you). Another way of putting that is that you're surrounded by a 170dB sound wave, which may well be enough to cause serious (fatal?) injury and would certainly damage your hearing. To keep the shock wave under 150dB (which is still very loud), you'd have to restrict yourself to changes of less than 0.7kPa, e.g. from sea level to 60m. However, if the pressure change were experienced over a longer time, even just 100ms or so, then I don't think that would apply. It would be more like sudden decompression on a plane (at relatively low altitude) – your ears would pop and you might faint, but nothing too serious. The other possible side-effect, going from low to high altitude, would be outgassing (as happens with divers if they don't decompress). Since your blood cannot hold as much dissolved nitrogen at low pressure, if it is saturated with nitrogen at sea level then that will come out of solution and form bubbles when you teleport to the top of Everest. You will get rid of the excess nitrogen quite quickly just by breathing, and the amounts would be less than with deep-sea diving, but it might be possible to sustain injuries this way. [Answer] Your hero MUST wear some kind of protective gear, mostly to protect the ears from the sonic boom as a volume of air, to all intents and purposes, disappears from the volume between him and the closest "layer" at way more than the speed of sound. The resulting backlash would be more than enough to incapacitate, and possibly even kill. Then, he has to first get as near to the Everest as he can. Say he teleports from a quarter of the world away, on the same parallel. His instant velocity at that point is about 1200 km/h in a given direction, with respect to the Earth's axis, due to the rotation of the Earth (it would be 1621 km/h on the Equator). When he appears on the Everest, that speed is now directed upwards (or, infinitely worse, downwards). His horizontal component with respect to the Everest frame of reference is nil since he teleported from 90 degrees counter-rotation-wise, on an Everest that also moves at 1200 km/h with respect to the Earth's axis. The two velocities compound so that he takes off at a 45° retrograde angle with the speed of a supersonic bullet (480 m/s). He doesn't feel acceleration at all, but the air (and, if he's inside, the ceiling) will smash at him like a hammer. The nearer he comes to the Everest, the less the problem arises. Actually, he'd do very well by teleporting in short stints, one or two kilometers at the most, thereby also acclimating to the lower pressure. By the way, he'll still need oxygen and breathing gear, or he won't last long once he goes above the 5-6000 m level. This kind of problems are expounded in depth in Vernor Vinge's [The Witling](https://en.wikipedia.org/wiki/The_Witling). Giri's people, the Azhiri, can teleport (reng) from one place to another, as long as they have been there (unless they're the super-powerful Federates), or reng objects from one place to wherever they are. The most skilled soldiers have visited the Poles, and can reng stones and pebbles - albeit only in one direction - with lethal results. [Answer] > > Due to theological reason, the protagonist have to go back and forth between Jericho (258m under sea level) and Lhasa (3658m above sea level). What are the possible short term and long term effect for such trip ? > > > Fainting and death, respectively. People have already told you about acclimatization to high altitudes. Truth be told though, going from Jericho to Lhasa instantaneously has less to do with mountain climbing and more to do with this: ![I could post a pic of people in a depressurized airplane but I decided to be nice instead](https://i.stack.imgur.com/IB6dw.jpg) People in airplanes survive (when they do) because of oxygen masks and repressurization due to the pilot taking the plane to lower altitudes. Your Darwin Award contestant, though... They might not faint in the first few seconds, but they will not survive such a sudden change in pressure without first aid and immediate access to an hyperbaric chamber. Even then, anoxia will take place. They might end up blind, deaf or paralyzed forever. Going from Lhasa to Jericho is probably survivable, but [not without consequences](https://en.wikipedia.org/wiki/Oxygen_toxicity). A quick increase in blood oxygen levels without the time for acclimatization may in the very least knock the teleporter out of their senses. --- The above would be valid if your hero could survive teleportation. The problematic part is this: > > Both volume exchanged keep their momentum ignoring the difference in velocity of the Earth's rotation. Falling toward Earth on the south pole, and teleporting to the north pole will result in the protagonist still falling. Flying westward and teleporting to facing eastward, will cause the protagonist to shoot forward in the eastward direction at the same speed. > > > In your previous question, I pointed out the changes in speed relative to Earth that come with teleporting. I believe you added this to reduce the amount of problems you had. If so, it had the opposite effect. In engineering, when you want something to lose speed gradually, you add brakes to it. If you want to stop something dead in its tracks, you add a wall in its path instead. In other words: if you character arrives with zero speed at the receiving end of the teleportation trip rather than shooting like a bat out of hell, from their point of view it will be exactly like hitting a wall at the speeds they would otherwise have. Hitting a wall at the speed of sound or above is a sure way to die. If you handwave it by saying that you are stopping all the atoms in their body at the same time... You need to turn their kinectic energy into something else, and nature's favorite form of energy trade is heat. A 70kg person moving at 300m/s, for example, will have $ \frac{70kg \times (300m/s)^2}{2} = 3,150,000 joules$, or 875 watt-hours of kinectic energy relative to the ground. Transform all that into heat, and it's approximately equivalent to the [energy release of 0.75 kilograms of TNT](https://en.wikipedia.org/wiki/TNT_equivalent). That is almost enough to completely destroy a car, so imagine what it would do to a human body. But you are not just zeroing out momentum to the ground. You are reversing it. So double everything I said above; That is, either double the impact felt by the teleporter, or double the energy release when they inevitably explode like a giant firecracker. [Answer] Ignoring the potential changes in relative velocity (hopping from the pole to the equator would leave him moving at a speed of ~1600 kph in a westerly direction), I believe that ear-muffs would probably be sufficient to cope with the 'mechanical' effects of pressure change. However, moving from sea-level to Everest or Lhasa may have a severe physiological effect. It takes a significant time to acclimatize to an altitude above ~3000 m (even ultra-fit climbers take several days to get to Everest base camp to acclimatize). Your protagonist could almost immediately lose consciousness if making a rapid jump. This is a known risk. For example, tourists flying directly from Kathmandu (alt 1400 m) to Namche Bazaar (3400 m) or Khumjung (3800 m) often need oxygen on arrival. Teleporting from at or below sea level would exacerbate this risk. [Answer] The problem would come from constant repetition of pressure changes IMO although it's difficult to be sure. The following articles discuss changes in barometric pressure due to weather. But in the case of almost instantaneous changes cause by teleportation, I'm sure your hero would experience problems to a greater degree. > > Increased mortality followed large temperature increases and large > pressure drops both in summer and winter months. Decreased mortality > was observed after large pressure increases and large temperature > drops in summer. <https://www.ncbi.nlm.nih.gov/pubmed/19526921> > > > --- > > Change in air pressure was significantly associated with onset of > Menière’s disease episodes, suggesting a potential triggering > mechanism in the inner ear. MD patients may possibly use air pressure > changes as an early warning system for vertigo attacks in the future. > <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4838262/> > > > --- > > Although it's been indicated as a possible cause for everything from > changes in blood pressure to an increase in joint pain, it can be > difficult to pinpoint barometric pressure changes as the definitive > cause for these issues when so many other atmospheric changes — like > temperature, precipitation and wind speed and direction — often > accompany shifts in weather. <https://www.mnn.com/health/fitness-well-being/blogs/how-changes-barometric-pressure-affect-your-body> > > > [Answer] Have the teleportation chamber rigged with atmospheric gases, temp controls and capable of holding any habitable temp & pressure required. Prior to transport, sample the destination (transport back a small sample), then at a safe rate equilibrate the chamber to destination atmosphere & temperature, prior to the transfer across. If the sample indicates extraordinary arrangements are required, in terms of suiting, or indications of great hazard, adjustments can be made. Never fly blind. There should also be the ability to image the destination exhaustively prior to transport to determine there is space available in and around the destinatinon volumne. Without some sort of dampening, the instantaneous mdv could be harmful/lethal. there needs to be in the tranport arc, facility of 'ramping into' the displacement vector of the destination volume in toto. This must account for lateral movement across the surface of the planet as well as vector, v & dv for any translations across the surface relative to the surface. ]
[Question] [ In particular, I want to know if a creature whose upper body displays bilateral symmetry and whose lower body displays tetramerism like a jellyfish is biologically possible. [Answer] How about 3 types of symmetry: Bilateral, radial and then tertiary bilateral? The wily sea cucumber has folded its echinoderm radial symmetry up to recreate bilateral symmetry of its distant ancestors. <http://www.geo.arizona.edu/geo3xx/geo308/FoldersOnServer/2003/Lab7EchinoArthro.htm> > > Echinoderms are generally radially symmetric, with adults displaying a > secondary pentaradial symmetry. The symmetry is secondary, because > echinoderm larvae are bilaterally symmetric. One group, the sea > cucumbers, developed a tertiary bilateral symmetry. > > > from <http://www.asnailsodyssey.com/LEARNABOUT/CUCUMBER/cucuMeta.php> > > During metamorphosis, as in other echinoderms, the larva of an > holothuroid changes from bilateral to pentaradiate symmetry. This is > seen mainly in the radial structure of the water vascular system, > including tube feet and associated tentacles. Superimposed on this > adult radial symmetry, however, is a bilateral symmetry, evident > externally in the division of the body into a ventral trivium and > dorsal bivium, and internally by the bilateral nature of the complex > hemal system and associated gut tube. Traditional thinking is that > phylogenetically, holothurians derived from ancestors with a primary > radial symmetry and later adopted a crawling habit of life with > accompanying secondary bilaterality. The later imposition of radial > symmetry is therefore generally considered a tertiary event in their > evolution. > > > [Answer] It should be very easy for an organism with even-numbered radial symmetry over part of its body to display bilateral or x-lateral symmetry (in which x is a factor of the superior even number) elsewhere. As long as both structures are divisible by the lower-order symmetry, the organism can be classified by that degree of symmetry. [Answer] I don't see any reason why not. While not a true example, an octopus or other cephalopod has bilateral symmetry for their mantel, and arms and tentacles that radiate out around their mouth. They are in fact only bilaterally symmetrical. There are also [starfish](https://en.wikipedia.org/wiki/Starfish#Taxonomy) that have bilateral symmetry as larva and radial symmetry as adults. [Answer] Yes, but it most likely wouldn't be perfect/near-perfect. As an example, take humans. Our hands have five-fold symmetry: if someone took a picture of a finger without any of the rest of the hand in the frame, it might be tough to tell which one it was a picture of. That's translational symmetry. However, there's a break in the symmetry: the thumb and pinky each only have one neighbor, and thus their roles are different, and they look different. It would be inefficient for parts which are in different positions to be identical, and inefficient in a way that's easily optimized by evolution. The organs and limbs of your organism would be similar; in this case the break in symmetry is that the quadrants have different positions relative to the bilaterally symmetric part of the organism. Therefore, the back and front quadrants (or the back quadrant, front quadrant, and two side quadrants) would be different from each other, on a level somewhere around how different your thumb or pinky is from your pointer finger. [Answer] A sphere has all types of symmetry simultaneously. And of course, an organism can be spherical. You mean one part having only one type of symmetry and the other part having another one type of symmetry. Yes, only spherical symmetry cannot participate in that. The upper part having two symmetrical hands and the lower - three symmetrical legs? It is possible, too. Imagine a Minopode - bull's head, human upper body and octopus' tentacles instead legs. ]
[Question] [ I'm playing with ideas for magic in my world. This is the same world as in [A corrupted religion](https://worldbuilding.stackexchange.com/questions/58656/a-corrupted-religion), in case you're wondering. In the world of {PlaceholderWorldName}, people can perform magic, but it isn't your average run-of-the-mill fantasy stuff. In essence, users can transfer energy. This involves decreasing the energy of a group of particles (source) and increasing the energy of another group (target). The energy can come from themselves (body heat, moving arms, maybe neural electricity?\), or from any other source of energy (moving air particles, or a hot object). No energy is created or destroyed and the type of energy is conserved (kinetic, thermal, etc). The energy is "transferred" from source to target. Both the target and source need to be close to the user. For simplicity, I'll define that the user must be touching both the source and the target directly during energy transfer* to perform a spell (one with each hand). No damage will occur from this, since none of the energy is directly transferred to the hands. The only magic involved is the selection of source and target, and the transfer of energy. All of the results from spells are purely scientific. This allows users to use "ingredients" to cause chemical reactions, channel energy from a large source to super-heat a small target, or vice versa to cool. They can also move or suspend objects, and harness things like lightning. I expect I will have many questions stemming from this, but I will start with the basic one: What sorts of simple spells are possible using this system, with scientific explanations? The elements of magic correspond to the following types of energy: * Light By reducing the light emissions of a light source, the user can cause the target to emit light of the same frequency. * Thermal By reducing the heat energy of any object above absolute zero, the user can increase the heat energy of the target relative to specific heat capacity and other factors. * Electrical By reducing the current flowing through a conductor, the user can apply a current to the target. * Kinetic The user can apply a force to a target, given that an equal and opposite force is applied to the source. * Sound The user can reduce the volume of sound emitted to cause the target to emit sound. The waves cannot be altered, so the target will emit the same sound. --- P.S: I'm aware that types of energy somewhat overlap, such as sound being the movement of particles in a medium, but for simplicity magic users must use a source of sound to "create" sound, and a source of movement to move things, etc. (Note: I have missed out some types of energy which I think a traditional fantasy nation would not consider to be "energy" due to an incomplete understanding of science, or other religious explanations being favored by the majority. These include elastic potential, gravity, Electrical energy is from the weather, or static, since technology as far as steam power has yet to be introduced, let alone electricity.) \On taking energy from yourself, this brings into account the possible limitations on damage to the user's body. This is a topic for a different question and does not need to be solved here. [Answer] What it sounds like, and please correct me if I'm wrong, is that you have a mostly real-to-life physics system with two key modifications: Magic-users can influence energy flow using their minds * The [laws of thermodynamics](https://en.wikipedia.org/wiki/Laws_of_thermodynamics) are suspended I'm not gonna lie, that's really, really cool (no pun intended). A relatively simple change, but enormous in its implications. So conservation of energy is still in effect, and a magic user can't actually convert energy themselves. But with this ability the conversion of energy becomes way simpler to be sure. This is one of the biggest issues we have today even: how do we turn, say, the chemical energy of gasoline into the kinetic energy of a car? We answered it with the internal combustion engine, but let's look at it from a magic user's point of view. When gasoline burns, it gives about [48.7MJ/kg of energy](https://en.wikipedia.org/wiki/Energy_density). A modern, top-of-the line internal combustion engine gets about [38% efficiency](http://www.greencarreports.com/news/1091436_toyota-gasoline-engine-achieves-thermal-efficiency-of-38-percent), which lowers the energy of the gasoline to a functional 18.5MJ/kg of energy. But imagine if you could capture all of it with no loss. A magic user from your world would be able to light gasoline on fire can siphon off 100% of the thermal energy being produced. You now have a way to start a fire, melt through rock/metal, or create a thermal breeze, and your magic user needs 1/3 the amount of combustible material the real world would need. Now lets look at medicine. At our most basic level, all humans are is a [series of interlocking chemicals and reactions between those chemicals](http://www.biochemistry.org/?TabId=456). Now, if we let the generalization 'chemical energy' apply somewhat ambiguously, then healing spells become quite possible. By simply holding a plant leaf, or a protein bar, or essentially any edible or chemically active material a magic user could channel that chemical energy into repairing damaged tissue. This same principle applies to underwater breathing: all you need is some form of chemical energy and you can break water down to get your oxygen for as long as you want. How about engineering or construction? Magic user's would be capable of impressive feats of strength: imagine a magical construction site where a boulder or large rock is mounted in a shaft. Whenever something needs to be lifted, the boulder is dropped, a magic user catches it, then slowly transfers the kinetic energy into a huge I-beam to make it lighter. With thermodynamics out of the way, quite literally anything is possible. [Answer] A gun User holds a tiny, dense object in one hand (even a grain of sand could work), and a bigger, heavier object in the other. User throws big object upwards with ordinary muscle power. When the object falls upon user, user transfers its kinetic energy into the small object. User is unharmed by the (now stopped) falling object, smaller object flies out very quickly. If user catches the big object in the same throwing hand, and is holding more tiny dense objects in the other, user is ready to cast the spell again. This spell is simple and highly scalable: with an increasingly small and dense target, and an increasingly fast and heavy source, it is possible to give the target speeds amounting to significant fractions of C. Nigh-invulnerability User redirects incoming energy of all types to a pebble or piece of dirt stuck on the underside of their shoe. This can be sustained indefinitely, if user can purposefully avoid transferring the thermal energy of the air that is being touched and breathed. All conventional methods of warfare would be rendered obsolete by this simple spell; melee, chemical and biological warfare would become the most viable alternatives. [Answer] Young mages must be taught to keep their targets large and their sources small. For the world is fragile on the smallest scale... Take all of the light in a well lit room and focus it into the eyes of your opponent. They will probably never see again. Focus the warmth of a sunny day into a single grain of sand, add the pressure of the whole sky above you and a mushroom cloud will mark your passing from this world. There are individual, life critical nerves in every human body which could be scorched beyond function by less electricity than is generated by dragging your feet across wool carpet on a hot dry day. The secret to living long enough to learn magic, is to think big when choosing targets. [Answer] Magic is weird, because possessing even "modest" magic enables all sorts of miraculous outcomes. For example, you say that magicians can transfer "light" energy, whatever you believe that to be. Then they could banish darkness from their cities by simply transferring a small amount of luminous energy from the day site of the planet to the night side; the illumination provided by lightbulbs is hundreds of times weaker than the illumination provided by the sun at noon; nobody will notice the slight decrease of the light of the day (not even photographers), and yet it will make a tremendous difference at night. The transfer of "thermal" energy is even more wonderful. You can make a nice (almost) perpetual motion machine in this way. Just take a plain cylinder with a piston in it, and transfer thermal energy from the ocean (or from the Sun, or from Betelgeuse) to the air inside the cylinder; the air will expand, pushing the piston; evacuate the air, reset the position of the piston, repeat: you have a motor. And refrigerators are even easier, obviously. The magician can extract water from the air in the middle of the desert by transferring thermal energy from the air to Pluto: water will condense and fall as rain. The transfer of kinetic energy is quite a bit more complicated, and it will play havoc with the physics of your world. You see, in our physics kinetic energy isn't necessarily conserved, but momentum is. Now, imagine that you have a nice moving mass of air, what is usually called wind, and the magician transfers some of the kinetic energy of that mass of air to, say, a ship. The speed of the wind cannot decrease, because of the conservation of momentum, and neither can the speed of the ship increase, for the same reason; yet, somehow, energy is conserved by the particular brand of magic you propose... The consequences are interesting. Now, both sound and light are waves. They carry energy, true, but they also have a wavelength and a phase. What happens with the wavelength and phase when you transfer the energy? Interesting. [Answer] To compare your magic system with other magic systems, I tried recreating classic spells with it: * Fireball: Hold some sand or dust (gunpowder works best for obvious reasons) in one hand, then jump, and as you land, transfer into the dust all of your kinetic energy as well as a ton of heat from the surrounding air (or, if there are limits on how much heat can be transferred from air, you'll need a hot coal or something as an additional component). This should launch a sizable explosion. * Invisibility: Absorb all the light hitting your body and convert it into identical light leaving your body. If you do it precisely, you will be completely invisible. I suspect that it would take a ton of practice, and maybe only expert mages could do it, while beginners would just seem to glow or turn random colors. * Levitation: I don't see why you can't take your kinetic energy from falling and transfer it into a flywheel or even the air around you, thus keeping you hovering in midair. Incidentally, mages should just carry flywheels around with them everywhere, since they can jump a few times to "charge" them and then use the kinetic energy in them as a source for super strength (flywheels also help your range for the fireball spell I mentioned earlier). * Fly: A natural extension of the previous spell, but it's quite limited. You can hover in place easily, but actually moving requires you to have a source of large amounts of kinetic energy on hand. The best way I can think of to fly is to start on a high cliff or building, you can jump off and, by funneling energy back and forth from the flywheel, change your direction of motion. An interesting consequence is that you can never fly higher than where you jumped from, since that would require too much energy. However, you should be able to glide laterally for long distances, and have good maneuverability if you can transfer the energy back and forth fast enough. * Lightning Bolt: This takes way more electrical energy than is feasible unless you have a car battery on hand as a magical component. Stick with fireballs. * Ray of Light: Hold a lens and move all of the light energy hitting you through it. If the mage makes sure that the light goes in straight, it should produce a fairly effective long-ranged attack at the focal point. A more experienced mage might be able to make the light they transfer hit at an angle that changes the range, but I imagine it would take serious practice to be able to use this in battle. Again, Fireball (or the gun trick mentioned by Anonymous) is a more effective battlefield spell. * Chill Touch: Among all the awful things a mage could do if they got within touch range of an enemy is simply drain all the heat from their body. Bonus points if you freeze someone to death with a touch and simultaneously use their body heat to shoot another guy with a fireball. * Shield: A cool trick for a mage in a tight spot. They can focus on their cloak, transmitting all energy it receives into their flywheels or the ground. This works well for swords and the like, but if they can't dissipate the energy too quickly (a bullet or arrow hits faster than human reaction speed) then for ranged attacks they could use... * Control Water: Touch a large source of water. A river or waterfall, whether natural or man-made, is best so that you also have plenty of kinetic energy on hand. Use that to move the water in midair in whatever formation you like, keeping your hands in contact with part of it, and siphon off its energy as it starts to fall to keep it hovering. With this, you can create elaborate shields that will stop most ranged projectiles. If your source of energy is continuous (like a river), you could channel it into the water and make it deform and hit or cut enemies. Basically, waterbending. Things your magic system probably doesn't do: Teleport, Charm Person, Summon Monster, Transmutation. Final, unrelated note: if the planet in your setting rotates, DO NOT let your mages siphon energy from it. It makes them way too powerful, and eventually they'll overuse it and the world will stop spinning and it'll kill everyone. [Answer] Simple transfer-energy spells * Death touch: stopping the heart of any person by transfering its kinetic energy to the rest of their body in uncontrollable spasms. A trained magic user would be however able to prevent that. * Kinetic wrestling: boxing magic users could use energy transfers to trip an opponent trying to hit them, by transfering the energy of attacks to the surrounding air in bursts. * Alchemical transformation: realign the target's chemistry and create new chemical bonds as desired by burning the source. Using a single object/material as source and target would allow one to modify it by burning off surplus material and transferring the created energy to the core of the object. * Crafting weapons/items: by transferring the chemical and thermal energy between parts of an object one could burn and dissassemble while hardening or cooling other parts to create weapons, extra energy could be drawn from the ground or air. * Light: transferring heat from one's body to a small piece of wire would cause it to begin to emit light, although this would only be a heat transfer. For a "scientific" explanation this kind of magic would require the energy for the "energy transfer" to actually be powered from some occult source, a kind of nation-wide energy bank, accessed for instance by creating energy conduits such as magic circles, or wearing garments/tattoos allowing one to draw from this common resource. What you are describing by the way is the magic system in the Fullmetal Alchemist world. [Answer] Basically Anything Because... You'd Violate the laws of Thermodynamics You'd violate the second law, because you'd be able to move heat from a cold object to a hot object without an sufficient input of energy. By violating the second law, you can do an infinite amount of work. Simply create a heat engine. A heat engine is something that does work from heat flowing from a heat reservoir to a cold reservoir. You can set the world as your cold reservoir, and continuously move energy from the cold to the heat reservoir. You'd also violate the conservation of energy Here is an interesting thing to do. Remember that the conservation of energy only applies to within a inertia reference frame. You can use this to create energy. In your stationary reference frame, have 2 very large blocks side by side not moving, with a middle lane in between them where you can run, and where you can touch both at the same time. Currently, they have 0 kinetic energy. Run in between them. In your new moving reference frame, you are actually stationary, while the blocks are moving toward you, meaning they have kinetic energy. Move the kinetic energy of one block to the other completely. Now, in your moving reference frame, one block is stationary, while one is moving past you much faster. Stop running. Now, in your stationary reference frame, Both blocks are moving in different directions, and their total kinetic energy is non zero. Ultimately, it depends on your understanding of Science But basically, you can do anything. Even if you say you can't transform the type of energy, you actually can. Attach a piece of string to the Earth, and hold on to it. If the sun is directly above you, transfer the gravitational potential energy you have with respect to the sun to the Earth. What this means is that you will be moved closer to the sun (aka, you are now flying). If the energy transfer/second is not infinite, this means you are now moving upwards at a certain velocity. Aka, you now have kinetic energy (and I'm pretty sure you created it out of nowhere too). By transferring gravitational energy with respect to the billions of celestial objects, you can basically have free flight. You can kill someone by transferring their biochemical energy elsewhere. You can transmute things by transferring nuclear potential energy. You can probably collapse a building by moving gravitational potential energy of the ceiling to the floor. Just like how you can fly, you can lift things. You can create a vacuum, by transferring heat energy out of air, and thus making them into liquids. You can move the mass energy of one object to another, with unknown consequences. Ultimately, you can do almost everything. I haven't thought of a way to destroy the Earth yet, but I'm pretty sure it's doable. [Answer] Just wanted to add, windy storms will probably be a mage's best friend. They are basically giant reservoirs of free kinetic energy. If a mage encounters an army during a storm he could just transfer a tiny bit of the energy in the wind into the ground below their feet to make it explode. Also by moving all of the thermal energy, you could freeze everything in one area while incinerating another. [Answer] Stand on a boulder as it's being pushed off a short drop. Direct the kinetic energy into literally anything else you're touching. Maybe take all that energy from the big rock and channel it into a small rock. Big rock goes slow, small rock goes fast. ]
[Question] [ In the world that I'm building, life on Earth has gotten pretty unbearable for some. My first thoughts are over-population, pollution, war, etc. A company/government comes along and tells you and your family that they have the ability to resettle you, not to a new location, but to a fresh "new" Earth. They would do this by sending you back in time to an alternative Earth (no cause and effect relationship to cause paradoxes) where the travel was geographically fixed to a specific time. The issue that most people would have, in my opinion, is that it is a one-way trip, with zero feedback to indicate if people arrived successfully or what was waiting for them. The company claims they were instructed by a message from a long lost civilization who accomplished something similar, but met an unfortunate fate early on (example: Atlantis). Kind of reminds me of the television show, Terra Nova, but I'm putting a different kind of twist to the time travel portion. How bad would things have to be for people to volunteer to be part of this program, given that they have no concrete evidence of their safety? [Answer] That's a hard question to answer because there are people who would go now and there are people who would never go. Many conspiracy theorists would say that it is [some organization]'s attempt to get people to volunteer for euthanasia. The rest of the conspiracy theorists would say that the first set are backed by [some other organization] and are trying to keep people from the best thing since sliced bread. The majority of the people will believe whatever the news tells them to believe. People who would go today: * Adventurers who would go just for the thrill (Mars One has already been mentioned) * There are those who just don't like being around people. Look at the off the grid folks in the US northwest (Montana, Wyoming, etc.) a bunch of them would go now just to get farther away from the crowds and the government. * Then you have those on the run (from the mob, police, debt collectors, ISIS, drug cartels, etc.). Some fraction of them would go because the unknown isn't as bad in their minds as the known. * Some people have starving families, if you tell them that they can have a plot of land to feed their family, many would go; especially from third world countries. Then there is a spectrum. The worse things get the more people will go. What percentage of the population do you want to get rid of? Finally, there are those who would never go. The devil you know isn't as bad as the devil you don't know. A better question is, if they can't send back materials, who would bother paying for building and running this dimensional gate? England foisted off a lot of their riffraff on the US and Australia but they also got goods sent back and made a lot of money from it. [Answer] Any situation where local perspective is negative will trigger emigration, even if the destination is a one-way ticket and the outlook is highly uncertain. Overpopulation or famine in the source country will in itself already be sufficient. Pull Historically the [US frontier](https://en.wikipedia.org/wiki/American_frontier) was a place where women died in childbirth and people were lost in winter when the weather was more harsh than they were used to. The body count was high, expectations however were sky high and provided a very strong motivation. Census Population 1790 3,918,000 1800 5,236,000 1810 7,036,000 1820 10,086,000 1830 12,785,000 1840 17,018,000 1850 23,054,000 Push For example the [Irish Great Famine](https://en.wikipedia.org/wiki/Great_Famine_(Ireland)) triggered mass emigration and millions of people left the country, many towards the new world. The emigrants fled harsh conditions, died in numbers along the way and had trouble settling in the new country. This did not seem to stem the flow any bit, as the population fall in Ireland was as much as 50% down from some 8 million in 1841. [![enter image description here](https://i.stack.imgur.com/tj5bK.png)](https://i.stack.imgur.com/tj5bK.png) References: <https://en.wikipedia.org/wiki/Demographic_history_of_the_United_States> <https://en.wikipedia.org/wiki/American_frontier> <https://en.wikipedia.org/wiki/Great_Famine_(Ireland)> [Answer] The answer really depends on how convincing the company is in their sales pitch. With complete lack of communication from the other side, you are putting 100% faith in the company's model of what they think is happening. If this company has a history of taking knowledge from the Ancients and turning them into testable working products, the confidence in the company's position could be very high. On the other hand, if this is the first attempt at unlocking ancient technology, and the product looks like an oversized meat grinder or wood chipper, confidence will be very low. If the company can demonstrate scientific theories to show that it should work, that raises confidence. If it looks like you'd have to break a few popular scientific theories in order to get it to work, that lowers confidence. There will always be takers. You may have to work hard to find them, but they're always there. If you go to a war torn country which is so impoverished that the locals have worked their way down the food chain from grains to grasses to mud cookies and fight over access to the best mud, you'll find people who are willing to take a risk. (And yes, mud cookies are actually a thing. In our world, there are populaces which are so far beyond starving that they indeed eat mud for its nutritional value) There will also likely be religious cults that pop up using your device as proof of their life everafter. Those groups would be quite easy to ~~toss into the woodchipper~~ convince to undertake a less than certain fate, because while you would be uncertain they actually would be certain about where they were going. [Answer] Remember Nigerian princes and Mars One have a working business model. Especially with increased population, unless you mean to be sending very large numbers of people you should be able to count on suckers. Adventure and independence are powerful draws, during the settling of the American West people came thousands of miles to die in the desert on the hope of free land. Certainly they had some reports of previous people, but they included tales of gruesome murders, disasters and atrocities. If you insist on rational trust; sharing a name with a popular organ transplant or dog food company may reduce the numbers of volunteers. Investing in training and resources for volunteers might aid their credibility. [Answer] # Lots of people will go, right now [![enter image description here](https://i.stack.imgur.com/4baGO.jpg)](https://i.stack.imgur.com/4baGO.jpg) Here are about [13.5 million volunteers](https://en.wikipedia.org/wiki/Refugees_of_the_Syrian_Civil_War). History has never been short of refugees, and I doubt the future will be, either. ]
[Question] [ How much would the gravitational force (on earth) have to increase to make air-travel impractical (not impossible as escape by space flight to other planets would be a nice option). But to a point where the use of fixed winged aircraft becomes impractical as the energy required by propeller/jet engines becomes so costly (with current technology) that the amount required becomes impractical for commercial use. If we know the gravitational force required to achieve the above. What would be the smallest asteroid strike to achieve this and could it be done with causing global collapse of civilization (maybe some local collapse). i.e strike at the center of Antarctica (melts ice but no dust cloud or tidal wave). [Answer] Commercial flight would be the least of concerns on Earth if the gravity rose that much. Surely for current planes, where the rise would need to be of order of some 30% to even make "lightweight" flights (mail, passengers) not viable for airplanes that can lift 40+% of their mass as heavy cargo, the effects of such gravitational increase would be on extinction level of problems. First, the atmospheric pressure would increase. Making flight easier, but suddenly oxygen concentration becomes dangerous to health. The climate is in ruin as water evaporation point would change - enormous droughs. Ecological disaster, as many airborne but less "powerful" species would lose ability to fly. Gas solubility in water would change, leading to much more acidic water with carbon dioxide dissolving easier. All satellites would crash. Winds would get much more dangerous - not only due to the climate change which would surely cause hurricanes, but simply because higher air pressure carries more energy at the same speed. Lots of chemical processes (probably including fuel combustion in car engines) would be affected. The shift of load on earth crust would lead to powerful earthquakes. Seriously, if you want to get the airplanes out of the air, think of some less drastic way than increasing the planet gravity. [Answer] Short answer for air travel The practicality does not depend upon the mass or gravity of a body. It is the ratio of surface gravity to air density that makes it practical or impractical. As long as the ratio of gravitational acceleration to air density remains constant, air travel remains practical. Increase surface gravity while keeping air density constant will eventually make air travel impractical. When it becomes impractical depends upon how efficient your engines are and what you deem to be the minimum sized payload worth your while. If you doubled planetary gravitation while keeping air density constant, commercial air travel would be impractical (though some special planes might still be possible). For example, take the numbers from a [Boeing 747](http://en.wikipedia.org/wiki/Boeing_747#Specifications). If you doubled gravitational acceleration, the aircraft could take off if it was empty but it could carry no cargo. ``` Take off gross weight: 333,390 kg 1 g empty weight: 162,400 kg 2 g empty weight: 324,800 kg ~ 333,390 kg ``` In order to double the Earth's gravity, you'd have to double the mass of the planet while keeping the radius the same OR keep the Earth's mass the same and decrease its radius to 70% of current. It would take the collision of two bodies of mass of Earth or larger to do it and that would liquify the Earth - No survivors. Plus the atmosphere and hydrosphere would be permanently lost. There is no scenario that I can envision that could do this and leave any survivors. Short answer for space travel IMO, chemical rockets are on the verge of being impractical now. Even with staging (which makes the performance better) they aren't widely used now except as a specialty transportation mechanism for very high value transportation. So if you doubled surface gravity, your only practical method of space launch might be one of these that I documented on [The Case for Space](http://jim2b.blogspot.com/search/label/The%20Case%20for%20Space) section of my blog: 1. [Nuclear Pulse Propulsion](http://jim2b.blogspot.com/2010/11/the-case-for-space-viii-nuclear-pulse.html) 2. [Laser Launch/Light Craft](http://jim2b.blogspot.com/2010/09/case-for-space-v-lightcraft.html) 3. [Ram Accelerator](http://jim2b.blogspot.com/2010/10/case-for-space-vii-ram-accelerator.html) 4. [Light Gas Gun](http://jim2b.blogspot.com/2010/10/case-for-space-vi-light-gas-gun.html) 5. [Coilgun](http://en.wikipedia.org/wiki/Coilgun) Basically only engines with very high specific power (e.g. nuclear bombs) or don't have to carry their propellant would work for space launch for a 2g planet - air density doesn't affect this much except to make it more difficult. Lift - Weight From a first order analysis, lift is the force required to lift the aircraft off the ground. Lift must equal the mass of the aircraft in order to lift off. $$ L = \frac{m\_aM\_pG}{r^2} \rightarrow L = m\_a a\_p $$ $m\_a$ - mass air vehicle $M\_p$ - Mass of planet $a\_p$ - Planet's gravitational acceleration G - Universal gravitational constant r - radius of the surface of the planet The lift equation is: $$ L = \frac {1}{2} C\_L \rho V^2 $$ L - Lift force $C\_L$ - Coefficient of lift (dependent upon aircraft & wing shape) $\rho $ - Density of air $ V^2 $ - Velocity of vehicle squared So putting them together we get: $$ m\_a a\_p = \frac {1}{2} C\_L \rho V^2 \rightarrow a\_p = \rho \frac {C\_LV^2}{2m\_a} $$ Simplifying we get $$ \frac{a\_p}{\rho} = \frac {C\_LV^2}{2m\_a} $$ This equation shows that $ C\_L $, V, $ m\_a $ remain constant if the ratio of $\frac{a\_p}{\rho}$ remains constant. Drag - Thrust In addition to weight issues, you must also pay a drag penalty. The drag equation is identical to the lift equation but uses a different constant. You can approximate the drag coefficient as 1/10 of the lift equation. $ C\_D $ ~ $ \frac{C\_L}{10} $ So $$ D = \frac{1}{20}C\_L \rho V^2 $$ The turbine engine thrust equation is: $$ D = T = \left(\dot{m\_a} + \dot{m\_f} \right)v\_e - \dot{m\_a}v\_i $$ $\dot{m\_a}$ - Mass flow rate of air, which can also be expressed as $\dot{m\_a} = \rho A v$ $\dot{m\_f}$ - Mass flow rate of fuel $v\_e$ - Engine exhaust velocity $v\_i$ - Velocity of air at the inlet (when multiplied by $\dot{m\_a}$, this is also known as ram pressure A - Area at the inlet or exhaust (depending upon where you're doing the calculation) But it is usually approximated with the following (the fuel's contribution to thrust is mostly through heating): $$ D = \dot{m\_a} \left(v\_e - v\_i \right) $$ I am not going to go through all the gyrations to do this exactly. I'm assuming the inlet and exhaust are the same size (they almost never are) but I simply want the feel of the equations and for this purpose it works. $$ D = \rho A v \left(v\_e - v\_i \right) $$ Combining with the Drag equation and we get $$ \rho A \left(v\_e^2 - v\_i^2 \right) = \frac{1}{10}\frac{1}{2}C\_L \rho V^2 \rightarrow \frac{1}{10} m\_a a\_p = \rho A \left(v\_e^2 - v\_i^2 \right) $$ Substituting in the Lift equation equivalence to aircraft mass times surface gravity, I get: $$ \frac{a\_p}{\rho} = 10 \frac{A \left(v\_e^2 - v\_i^2 \right)}{m\_a} $$ Anyway long story short, it looks like its Drag remains the same as long as the ratio of surface gravity to atmospheric density remains constant. [Answer] A better way to prevent general air travel is not so much to make it physically implausible, but to make it impractically costly. When the [Icelandic volcano](http://en.wikipedia.org/wiki/Eyjafjallaj%C3%B6kull) erupted and delivered a lot of dust into the atmosphere flights were [grounded for ages](http://news.bbc.co.uk/1/hi/sci/tech/8621992.stm). The dust was not so bad that it affected people of the ground - I recall my car had a layer of dust over it so I was obviously breathing it in and I never noticed anything untoward, but the dust would have affected planes flying through it at speed, the dust would sucked into the very high-precision jet engines and would damage them, if not causing them to fail eventually, landing the airline with a huge bill for repairs. Note that some planes did fly, particularly turboprop ones that were used to measure the density of ash in the atmosphere. Incredibly fine dust will clog air filters, particularly if they have a lot of air sucked into them, in a way that will not affect something that works slower like your lungs. So put something in the air that is not good for high-pressure or high-speed machinery. Pollen, dust, pollution will all do. [Answer] As others have pointed out, changing gravity is not really going to bother air travel much, and is going to create major problems elsewhere. As for the idea of an asteroid strike changing gravity... Well, any asteroid big enough to change Earth's gravity enough to be measurable even by sensitive instruments is going to turn the Earth into a ball of molten magma. If you want an idea of what modern society would be like without air travel, remember that we have a real-life example: the days after the 9/11 attacks, when commercial air travel was shut down in the US. Research that, and extrapolate. ]
[Question] [ One of the reoccurring concepts in my worldbuilding has been the existence of a caste based meritocracy. The castes being Guardians, Engineers, Scholars, Administrators, Artisans/merchants. While brainstorming an idea came to me: What if people in this society were not paid in cash but in some manor of redeemable acknowledgement of their contribution and value to society. Something like the [whuffie](http://en.wikipedia.org/wiki/Whuffie), only tied to one’s societal contribution instead of to popularity as in a reputation-based economy. It would be awarded by the state at regular intervals based upon a citizen’s performance of their duties. Aside from that I haven’t a clue how this might work, if it could work at all. [Answer] ## The Way It's Supposed To Be Working Now We live in a society that is supposed to be a meritocracy - rewarding those who work hard with better paying jobs. The issue here is that those wo already have better-paying jobs can pay for their children to get better paying jobs from the start, without earning it through merit. The means by which we reward merit becomes the means by which merit is rewarded. Ideally, every society should work such that those who work harder are rewarded for their hard work, but the exchange of any type of currency or thing of value throws that out of balance, because someone who stockpiles that which is valued, or 'games' the system to earn the most of those things regardless of the value of their work, is working to break the system as it is meant to function. ## Arbitration One way this could be prevented is by selecting people to arbitrate what tasks are of real value, and handing out either the means to redeem that work, or the products that are due to that work as they see fit. In smaller societies, this can work quite well as we've seen in the past with Native American societies being ruled by a Chieftan who would distribute to the tribe that which is needed. In larger societies, it tends to fall apart. A single leader cannot organize a large society on their own, so they must appoint delegates to run smaller sections of society. They then delegate their own delegates, and so on and so forth. A single deligate who is corrupted can then spoil what is supposed to be a fair and equitable society. ## Not An Economy What about a world where we don't have an economy at all? A post-scarcity society that doesn't have to concern itself with the distribution of vital goods? Under an ideal situation, all of life's necessities would be provided for, and luxury items would be the only thing separating individuals by wealth, which could be made trivially in any case. But as I said, this would be an ideal, and runs into many problems - how would society provide goods to everyone? How would they be distributed along a large and complex set of political boundaries? How would society ensure that no individual is bereft of their basic needs? How would luxuries be distributed? Would there even be a need for work if this distribution is perfect? Answering these questions is the exercise of writing a utopian work of fiction, or sometimes a dystopian work of fiction if society hasn't solved these problems. We're still working on the problems ourselves, so barring technology that eliminates scarcity, that can distribute needed goods to all of humanity's individual peoples, and that does not disproportionately distribute luxury good to some while others are left wanting, we will be stuck dealing with the logistics of trying to create a merit-based society. [Answer] > > How might a Merit based Economy work? > > > ## It wouldn't. The problem is that people cannot agree upon what warrants merit, since some people will see one approach as deserving merit and others will see something else. Look at today's businesses - even within the same role, different people get different raises, even though they are "by merit". Worse, once you start getting into specialties, and then into the higher skill levels, fewer and fewer people know enough of the specialty at that tier to evaluate merit at all. So you get fewer people being able to dole out merit rewards until there's a clique of a very few who wield the power. Human nature would then take hold and it'd fall into reputation economy (at best). [Answer] I am the government. You are an engineer. Your brother is also an engineer. You repair our first major Space station habitation, your brother repairs a nuclear reactor in a major metropolitan area. I, the government, reward your brother for saving countless lives. You are obviously quite ticked to say the least. This is an example of why this economy wouldn't work. To make an economy like this work, you would need a few things. * Everyone devoutly supports the government * Universal acknowledgement of the governments' say as final * A pre-defined scale of importance that encompasses every single possibility, no matter how remote, that defines the rewards that will be handed out for the completion of each beneficial activity The first two are extremely closely related. You could look at North Korea as an example of how to achieve those (some North Koreans disagree, but in the end those who speak out are executed or imprisoned). You would need the final bullet to stop major conflicts like the scenario above from happening. The conflicts that would otherwise occur would, as stated in a previous answer, quickly make it into a reputation deal. The scale would contain the possible rewards for every possible action performed by individuals in each caste. This obviously makes no sense, and therefore it would fail quickly, then: Back to using money! [Answer] I think you need to consider exactly what you're defining here. I think you can do this, but your society will be problematic, and you'd have to embrace that. There are three aspects. You want a 1. redeemable reward that is 2. allocated based on merit 3. as evaluated according to contribution to society Let's consider two out of three. ## 1 & 2 = Capitalism Yeah, yeah, capitalism isn't perfectly merit-based, but whatever. Roughly, what your talking about is one party evaluating someone else's contributions to private ends and rewarding accordingly. #3 would have to be pasted on by a central authority that redistributes based on corrections for private versus social returns. But most capitalist economies do some amount of this: funding scholars and teachers and police, taxing corporations. ## 1 & 3 Aristocracy, Caste System, etc. If you have redeemable rewards based on contributions to society, than your society has a strong rankings of tasks according to how much each contributes. Those who function in this system do receive some sort of pay, i.e. redeemable reward, but it is often rigidly set by norms and typically one's place is assigned by heredity. #2 must be pasted on, and how it is done depends on what you mean by merit. If it is overall merit at some central task, you assign caste or status based performance at this task, and status determines reward. This is similar to Lilliput (as in the case of a non-sense taks) or traditional Chinese bureaucracy, as in the case of a centralized exam. If you mean merit within a task, then you create room for rank, and cash wages are based on that. ## 2 & 3 Utopias I think this is what you mean, and it really gets at the heart of what is described in Utopias such as Doctorow's Down and Out in the Magic Kingdom and Edward Bellamy's Looking Backward. You see, if you picture yourself rejecting cash because that's not the idea you mean, then what you are rejecting is the full redeemability of the reward. That is what defines cash. Anything that essentially differs from cash is somehow not fully redeemable. Doctorow has Whuffie, which is not fully redeemable because you do not deplete it, but rather use it to queue up for scarce resources. Bellamy has a fully equalized ration of goods that does not depend on work, but more difficult or perilous work is compensated by shorter hours, i.e. excess leisure, which is not fully redeemable. The trick here is not thinking about how to paste on #1, but thinking about how to handicap #1 in such a way that the reward you speak of is not effectively cash. There must be things that money cannot buy that the reward can buy, unless you strictly forbid money altogether. Someone must decide what is valued; this can be a central government, but not necessarily. Maybe society as a whole has a long-lasting tradition of valuing some castes more than others, and castes have elders who recognize extraordinary individuals within the caste? I hope that's an interesting framework. [Answer] The Inca Empire had something in this direction. it was called [Mit'a](http://en.wikipedia.org/wiki/Mit%27a). Every male hat to devote labour force to the government as part of taxes. It was also used to trade between members of the society. Something like: If you build my house I will craft you some nice statues for yours. [Answer] I have an idea, though this may be quite a whole lot less realistic than the above answers, owing to my overactive imagination and general rejection of reality. But basically, what about some kind of karma-tracker? I had previously bounced this idea off a couple of my friends when we were toying with potential designs for utopias. Imagine a system where every good deed you do adds a bit to your 'Karmic bank' but every bad deed subtracts from it. How would they know when to add or subtract? I don't know, magic or something. Then basically, you do not 'pay' for goods with karma - you earn your goods with karma. A man with high enough karma could simply take what he needed - it would not subtract from his total karma. Karma is not a currency - its a measure of you as a human being. This system would be reliant on the fact that a person with good karma would not take more than what he needed, unless only to use it for good. However, even as we discussed this, my friends and I realized how disgustingly utopic this is, so please mess it up a little if you decide to use it. [Answer] I think you have to define 'merit' better. The society we have currently uses a meritocracy, with money as a token of reward for your efforts. Now, we all know that a banker is worth more than a nurse... don't we? Or do we? A banker uses his skills to generate much wealth that increases the tax coffers of the state which can then be used to hire more nurses, whereas a single nurse just does 1 person's worth of nursing. Is the banker therefore more meritorious within society as a whole? And is that why he gets paid significantly more than a nurse? In any case, even if you could define merit well, you'd still use money as a form of reward for people, only their pay would be tied to their merit rather than the 'evolved' or 'developed' version of it we have today. [Answer] I very much appreciated the Admins and Merchants comment, in many it solves your merit based karma economy problem. Right now we have merchants and admins who determine value. Perhaps in your society you don't have A supreme person giving out merit or karma but representives people voted on to give out such. In such a society people who are considered fair and moral would be the ones you choose to give out merit or karma. The first kings would have been those who were more powerful or popular the problems came in passing their power to their children- in a merit based world you would need people to not pass power or wealth on and to have every citizen start at a zero point that is at least fairly equal. [Answer] Merit tokens as fiat currency. Well, you did specify "in brief" in the question! But fine, longer answer: Some form of currency to exchange earned "merit" would have to happen. A black market would develop. At that point, you're back to normal transactions, but with strange side-effects. As an MMO programmer, one of the deeply ingrained things we learn when designing an economy is to consider our currency Sources, and Sinks. All the Sinks in this system seem to be the merchant class: that's where the "merit tokens" get spent, so it's where they end up. Though like I said, there'll be an untaxable black market of merit tokens between other castes, in return for services rendered. Though you could pass laws taxing service provision, too, in which case, those taxes too become Sinks. Admins are the ultimate Source, which distributes to other castes. So the Admins & Merchants have all the power in this economy, everyone else is essentially at their mercy. Admins decide your worth, your Merit point earnings. Admins then give you those points. Admins also take the points away from merchants almost 100% in order to pay the others. Through the black market, Merchants will become wealthy. However, Admins will become powerful, and by fudging the taxation numbers, will also become wealthy. And I hadn't realized when I was writing this up, but this describes the fall from idealistic socialism/communism to the strongly caste-based, centralized-power-and-wealth Communism systems that we saw towards the end of the cold war. In this light, this feels inevitable, and I can't see any good methods to prevent such a slide. ]
[Question] [ With the technologies that we have got, is it possible to completely migrate 1/3rd of the world's population to another planet which has characteristics similar to those of earth ? Possibly it will happen. [Answer] That would be no. While in 100 years we just might have the ability to travel to another planet (and if you count in solar system then it will be much less) it would still take a HUGE amount of resources to move 2,300,000,000 people off this rock. That is about 1/3 of the current population. Lets just take China, it's is 1/8th of the worlds population currently. Let's say we want to move them all, every single person, to the US. Just getting them on planes and boats and crossing. The 747 average about 500 people per flight (18 hrs), super tankers might be able to squeeze in 20,000 (WAG (Wild A$$ Guess) for a 2 week trip across the Pacific). So say half and half for this little number exercise. 500,000,000 people by plane and the same by ship. that would take 1,000,000 plane trips and 100,000 ship trips. Lets say there are about 1,000 of these tankers, it would take each 25 trips, at a month turnaround time for a total of 25 months. Say 1000 airplanes, are also working, that would be 1000 trips each, at a minimum of 1.5 days turnaround, that's 60 months of constant flying (no time for repairs and maintenance). So moving 1/3 of the the human population OFF THE PLANET is virtually nil. Remember this is just transporting them from one side of the ocean to the other, with a couple suitcases and enough food for a very short trip. The cost of putting people into orbit is significantly more, and having a living environment out there the cost goes up. Another WAG if we have 100,000 humans living off Earth in 100 years I think we're going to be doing pretty good. EDT Notes: Some Math errors were pointed out and (I found some more!) A couple by a factor of 10. I also bumped up the tankers passenger list from 5000 to 20,000 (might still be low) but don't want diseases to spread among those traveling and it isn't like those still waiting are going to die if they don't leave in time. Any other mistakes I missed (or added?) [Answer] As asked, the answer is no. To reach the nearest star in 100 years it would take at absolute minimum [100,000 times more energy than the Earth currently consumes to simply accelerate and decelerate 2 billion people](http://wolfr.am/33ZQkaPj). You can read all the gory details below. So I'm going to answer an expanded question, "could a third of humanity be living off Earth in 100 years?" I'm going to draw from existing estimates and near-future technology that's already been shown to work. No [zero-point energy](http://stargate.wikia.com/wiki/Zero_Point_Module), no warp or hyper drives, [no wormholes, and we're not going to solve gravity](https://en.wikipedia.org/wiki/Interstellar_%28film%29). What I will allow is more efficient and reusable rocket design, space elevators, efficient recycling, fusion power, and deep sleep chambers. --- How many people are we talking? [The UN estimates the population in 2115](https://en.wikipedia.org/wiki/Projections_of_population_growth) will be 6, 10 or 16 billion depending on how optimistic you are making it 2, 3.3 or 5.3 billion people we're getting off the Earth. I'd like to believe if we can organize an effort to move billions of people off the planet, we can get our population growth under control, but I don't think whether its 2 or 5 billion will have a big impact. --- Where are they all going? An orbital habitat? An uninhabitable planet in this Solar System? A habitable planet in another Solar System? Each of these affects two variables: the change in velocity required and the mass per person. How much stuff do we need to ship for the population to survive? If we send humans to a habitable planet in another solar system, that's a lot of velocity to escape the Solar System and get there in less than 100 years. You need to send enough food, water and air for that whole time (even sleeping) plus fuel to slow you down once you get there. However, once you're there, with a few tools you'll be self-sufficient like pioneers of old. An orbital habitat requires the least amount of velocity, just enough to get to low Earth orbit, but since we need to build the whole thing it requires moving a lot of mass per person. It has no resources to draw on but sunlight, and so all the food, water, soil and air will need to be shipped up. Recycling and growing food could be self sustaining, but there will always be leaks and inefficiencies, so periodic shipments are required. Going to an uninhabitable planet, probably Mars or maybe hollowing out some dwarf planets, requires more velocity than Earth orbit, extra fuel for landing a significant amount of mass, extra mass for machinery, shelter, food, water and air to sustain the population until they create a bubble. Farming is a dicey proposition as there is far less sunlight that far out (moving an asteroid sufficient to house billions of people to Earth orbit is out of the question). --- How are they traveling? Depends on where they're going. If it's Earth orbit we can allow multiple Space Elevators and Fusion Power. Since the power is coming directly from the Earth, and fusion gives us a huge power source, it effectively negates the energy cost of putting stuff into orbit. If it's to another object in our Solar System we can use conventional rockets, but it's going to take a lot of fuel to get there, and we're not coming back. 90% of the mass of a rocket is fuel. We could probably get it down to [about 5 tons of fuel for each ton of cargo](http://www.polaris.iastate.edu/EveningStar/Unit7/unit7_sub2.htm) (the difference from the 7 tons in the article is because our Space Elevator allows us to assemble our spacecraft in High Earth Orbit for free). If we're going to another Solar System, we have new problems. We need to escape the Sun's gravity, but that's peanuts compared to the velocity required to get to another Solar System in 100 years. Let's say we find a new Earth in [the closest star Alpha Centauri a mere 4.3 light years away](https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs). To get there in 100 years we need to travel at 5% the speed of light or 15,000 km/s. That's 600 times the velocity to get to Mars. It gets worse: our hypothetical colony ship has to slow down once it gets there. --- We can get some lower bounds of realism by calculating the kinetic energy required just to get 2 billion people up to the required velocities. Forget fuel, food, air, spacecraft and inefficiencies (which will likely add 10 to 100 times more mass). What is the minimum amount of energy required to fling the population to their target? (It turns out we don't need to go much further in our estimates than that). [2 billion people weigh about 1.4 x 10^11 kg](http://wolfr.am/33ZcjkIe). Let's plug that into [the kinetic energy equation](https://en.wikipedia.org/wiki/Kinetic_energy) for our various needs. Orbital Habitat via Space Elevator: [1/2 \* 1.4 x 10^11 kg \* (8 km/s)^2 = 4.5 x 10^18 J](http://wolfr.am/34todJ39) which is about 5% of the energy used by the US in a year. No problem. Even adding the mass of all the material and supplies, plus inefficiencies, this is well within our energy budget. Other planet in our Solar System: [1/2 \* 1.4 x 10^11 kg \* (25 km/s)^2 = 4 x 10^19 J](http://wolfr.am/33ZAoQ6h) which is half the energy used by the US in a year. Since the real energy required is likely orders of magnitude more, not to mention building a fleet of disposable space ships (the energy required gets far worse if they're coming back), that would be a serious problem. Reach another Solar System in 100 years: [1/2 \* 1.4 x 10^11 kg \* (0.05c)^2 \* 2 = 3 x 10^25 J](http://wolfr.am/33ZQkaPj) which is [100,000 times more than the world's energy consumption](http://wolfr.am/33ZNB5sE) so that's not going to happen. --- Conclusion? With fusion power, space elevators, and advances in recycling, farming, closed environments, and orbital construction it is plausible that a third of the Earth's population could be living in orbital habitats in 100 years. Anywhere else is infeasible, it would simply take too much energy to accelerate that much mass plus fuel, supplies and ship. The next question is why would you do this? Flinging people off the planet to control population or live in a better environment is a popular trope in sci-fi, but realistically you'd be better served spending all that time, effort, organization, material and energy fixing the Earth. The Earth, even a messed up Earth, is a far more pleasant environment than anywhere else. You could build a biodome or dig underground to get all the benefits and none of the drawbacks of living in an orbital habitat in space or doing the same thing on another planet without having to fling it all off the Earth. --- There is a better way to get the Earth expat population up. Send a much smaller population and then do what humans do best: make more humans. Assuming the Earth's population stabilizes, and assuming they land on a bountiful planet, with technology allowing a low death rate and long period of fertility, a small population can grow to a significant fraction of the Earth's in a few centuries. [Answer] 1/3rd of today's Earth population or 1/3rd of the future Earth's population? Most likely, it will be the future's. One easy way to be able to more easily move that many people would be to introduce some [sort of catastrophic event that reduces the Earth's population to a more manageable solution.](http://en.wikipedia.org/wiki/Moving_the_goalposts) > > another planet which has characteristics similar to those of earth? > > > With or without FTL travel? Without FTL travel, it would take much much longer than 100 years to get there, although that will be what it looks like from Earth, to the people on board, slow boating at high percentages the speed of light, it would only take much longer than 100 years. With FTL travel? They could be there already, humans on Earth could have come here from that planet, because [causality](http://www.theculture.org/rich/sharpblue/archives/000089.html) TL;DR: You would need to shift the goalposts by light years to be able to achieve your scenarios [Answer] Ignoring technology, there's another big problem. Let's use today's population - Google says it's 7.125 billion (OK, as of 2013). So, our goal is to move one third of that number to.. let's say Mars. It's close. That's 2.375 billion people that need to go from here to there in 100 years. Over 100 years, that's an average of 23,750,000 people going from here to there, every single year. That's if you could start shipping people today. So, let's cheat a bit - theoretically we could build one-way ships to Mars today (or soon enough), so we'll let you get your infrastructure up and start the clock with the first launch. Speaking of today, dividing that by 365 days in a year gives you about 65,000 people, every single day, for 100 years, that you need to move from here to there to make your target - and that's if we don't start the clock until the first rocket launches. For a bit of perspective - the average immigration to Canada and the US each year is 750,000 per year. You're talking about moving that amount of people every 11-12 days. You don't have a technology problem - you have a volume problem. :) (And even if we cheat and count births on Mars towards our billions, unless you can get a lot of people there very fast it's not going to significantly help you.) [Answer] Well, not the current population, but getting one person into space and killing everyone else is plausible. Of course, they might not be alive very long. However, you don't need to get anyone in space. Killing everyone would suffice, since $\frac 1 3$ is a valid answer for $\frac 0 0$. [Answer] No. The odds are no where in the realm of in our favor. First we'd need to find a planet similar to ours. (We're just barely beginning to find planets in other solar systems. While the number is increasing fast, we really don't know which, if any, could be similar to earth with the little data we have on them) Then we'd have to build transport for billions of people. (Assuming you're talking about the current population, we'd need some sort of transport for 2 billion people or so. Our current space endeavors have room for a dozen at most?) And then we'd have to get there. (This is the big kicker. Simply due the size of tne universe, the distance we'd have to travel is too vast--even at the speed of light--to reach a potential twin planet in the span of 100 years.) 100 years is just not a realistic timeline for that. I mean, unless Matt McConaughey finds that wormhole relatively soon. ]
[Question] [ My problem is whether they could grow crops to produce it. If not, what could be a substitute for a population, who live on wetlands in central European-like climate during early colonization era (17th century), so importing rice isn't an available option? What could they eat in general? [Answer] What can we make flour out of? > > Although most flour is made from wheat, it can also be made from other starchy plant foods. These include barley, buckwheat, corn, lima beans, oats, peanuts, potatoes, soybeans, rice, and rye. ([Source](http://www.madehow.com/Volume-3/Flour.html)) > > > So, we need starchy foods. Below is a partial list of foods that, when dried out, could be ground and sifted to make flour. [[1](https://www.webmd.com/diet/difference-between-starchy-non-starchy-vegetables)], [[2](https://www.healthline.com/nutrition/starchy-vs-non-starchy-vegetables#definition)] * Beans/Legumes (kidney, navy, pinto, black, cannellini, lima) * Beets * Carrots * Corn * Grains (Barley, Oats, Rye, Wheat, etc.) * Lentils * Parsnips * Peanuts * Peas (Green, Chick) * Potatoes (White, Sweet) * Soybeans * Squash (Acorn, Butternut) * Taro * Turnips * Yams But what's really important is what we mean by "wetland" The [simple definition](https://www.merriam-webster.com/dictionary/wetland) of "wetland" is "land or areas (such as marshes or swamps) that are covered often intermittently with shallow water or have soil saturated with moisture." But that's really two-dimensional. So let's try a more comprehensive definition. > > Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season. Water saturation (hydrology) largely determines how the soil develops and the types of plant and animal communities living in and on the soil. Wetlands may support both aquatic and terrestrial species. The prolonged presence of water creates conditions that favor the growth of specially adapted plants (hydrophytes) and promote the development of characteristic wetland (hydric) soils. ([Source](https://www.epa.gov/wetlands/what-wetland)) > > > The word of the day here is [hydrophyte](https://www.merriam-webster.com/dictionary/hydrophyte), "a plant that grows either partly or totally submerged in water." So, all we need is a starchy vegetable that's a hydrophyte. From [here](https://play.google.com/books/reader?id=KJqx_TnAE5YC&pg=GBS.PA50) we learn of some cool options: Starchy Hydrophytes * Cattail * Chinese Water Chestnut * Wild Rice Of these, the Cattail and Chinese Water Chestnut are specifically identified as starchy staples, making them ideal candidates for making bread in a wetland. However, your options are wider than that Remember that more complex definition of a wetland: "Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season." What's important here is that a wetland isn't simply underwater or swampy-soggy-muddy. A real wetland identified over a large area will include spaces of reasonably dry dirt for periods of time that could allow crops. My point is, you can realistically use pretty much any food from that first list and clear the suspension-of-disbelief hurdle with space to spare. But if you really want to make bread in a swamp, Cattails and Chinese Water Chestnut. But, if you're looking for some serious cool factor... Then let me suggest something a bit closer to peanuts but still a hydrophyte: the European Water Chestnut. > > This variety is called “trapa natans” by botanists, so you can see right away by the very different scientific name that it’s a very different creature from the “Chinese” Water Chestnuts. For starters, it actually is a nut [the Chinese Water Chestnut is a tuber]. These Water Chestnuts have been around for a long time in Europe. They were found in those now-legendary Swiss neolithic dwellings whose garbage piles were the object of much funding and study, where peas were also found. The variety has been in Europe since at least the Ice Ages. ([Source](https://www.cooksinfo.com/water-chestnuts)) > > > Boom, baby... [Answer] Rice [![enter image description here](https://i.stack.imgur.com/Y0toV.jpg)](https://i.stack.imgur.com/Y0toV.jpg) Rice grows in wetlands. Rice has existed in Europe since the Roman times. It came to Spain in the 10th century. It is believable there was rice in central Europe in the 17th century. There is no need to import. It can be made into a type of non chewy bread. But it is easier just to boil the rice. Historically baking things is a luxury and boiling is easier. Ducks [![enter image description here](https://i.stack.imgur.com/puXge.jpg)](https://i.stack.imgur.com/puXge.jpg) There are ducks on your rice paddies. They eat the little creatures that live in the water. Then you eat the ducks. Yum yum. Eggs [![enter image description here](https://i.stack.imgur.com/ncBF2.png)](https://i.stack.imgur.com/ncBF2.png) Make friends with the ducks by providing dry nesting boxes. They will lay their eggs in the boxes and you can eat the eggs when they are not looking. Cormorant Fishing [![enter image description here](https://i.stack.imgur.com/8fC5R.jpg)](https://i.stack.imgur.com/8fC5R.jpg) Get yourself a big cormorant and a small cormorant. Put a hoop around the birds neck so it cannot swallow the fish and train it to come back to you. Every dozen fish it catches it gets to eat one. Non Cormorant Fishing As above but without the cormorants. [Answer] It is possible for 17th century level Europeans to farm grain in swamps and marshes. Even in large shallow lakes. Check out this map of the Netherlands: <https://www.canonvannederland.nl/image/2017/7/1/kaart021b_landaanwinning.jpg%28mediaclass-fancybox-big-img.5a17fc1f47109709397ae88813c748b421ef8e41%29.jpg> It shows during what time land was 'reclaimed' from the Sea or inland lakes. Note that this map doesn't show all polders: some were reclaimed before 1300, and a large fraction of Dutch polders are former Peat bogs, reclaimed after the practice of digging up Peat transformed them into wetlands and lakes. Basically all provinces bordering the North Sea are made up mostly of reclaimed land. What you need is one (or some) of these: <https://en.wikipedia.org/wiki/Windmill#/media/File:KinderdijkWindmills.jpg> Surround 5-10km2 of wetland in two rings of Dykes a few metres apart, 5-10m high, digging the sticky heavy mud and clay by hand and transporting it using horse or ox-drawn carts over longer distances. Connect to a local river. Build a windmill to pump the water out of the wetland, and into the man-made canal in between the dykes. Dig trenches at intervals of a few hundred meters apart. These will collect rainwater and transport it to the windmill. Wait for the water to be pumped out and the soil to dry out. Plant crops on the very fertile peat-and-clay soil left behind. If there's a town nearby, they'll offer good money for the peat (for use as a primitive cooking and industrial fuel), so your locals may want to sell off some of the soil layer (wetlands tend to have very deep soil). However, if your locals dig out too much, they might find the clay that's left underneath too poor (in nutrients) for crops, and it would have to be a pasture for a few years first. [Answer] Of course it would, all you need are appropriate seeds to grind into flour, have you never heard of [rice bread](https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.wikipedia.org/wiki/Rice_bread%23:%7E:text%3DRice%2520bread%2520is%2520a%2520type,for%2520people%2520with%2520gluten%2520intolerance.&ved=2ahUKEwiBsr2M5d32AhUkmVwKHU3DBusQFnoECA4QBQ&usg=AOvVaw2XnIN-xq7D4sbrpd-OoXsR)? If your wetlands have deeper water cover than works for rice then either a variant of rice with longer stalks or some variety of reed like plant that has usable seeds would serve perfectly well. As for importing it, why would you need to? nothing stops you growing it right there, varieties of wild rice can be found growing in areas of both Canada and the US that don't necessarily have what might be considered the best climate for common commercially grown strains. So it's not so hard to produce viable variants for cooler climates should we want to and perfectly reasonable to posit early domestication of rice grains in cooler climates for alternate timelines. ]
[Question] [ ## How Regenerators work As I mentioned before, thanks to the Foundation, this setting has access to "Regenerators", enormous machines that can bring thousands of people back to life if necessary. Smaller regenerators also exist, though they're slower and can't resurrect as many at once. The way this works is that people imprint a "Save State" of their minds into soul gems, which are then uploaded into the Memory Repository, usually before a mission. If the operative dies and their soul gem remains intact, it's possible to extract a more up-to-date version and bring that back. Then they simply give the Regenerator the brain-pattern imprint and medical records, and it spits out the once deceased person. Well, growing the body takes some time, but it's not that bad. There is also a pretty infallible system to detect if a person is still alive, and if someone was to get doubled, the system would quickly stop recognizing the double as a double and give it the status "nth childof" with a link to the original person. Though the Foundation tends to avoid making doubles in the first place, they might cave in from enough pressure. --- However, in one of my battle scene drafts, Captain McKenna is with a dragon and a gryphon, trying to get to their mission objective. But then they encounter his old "friend". After McKenna quickly sends his squadmates away, we get this line from old friend: > > You were never one of us. You are nothing but a usurper, a false idol. My eyes have been opened. Let me help you to see, Captain. And > this time, you won't be coming back anytime soon." > > > The gryphon and dragon finally get to the other captains and tell them what they saw. The other captains go full panic mode and rush to McKenna's aid. --- So, there is a way to delay someone's regeneration for long enough to cause serious problems. This time varies but can be as long as 15 years. Furthermore, if someone's regeneration gets delayed, there's nothing the Foundation can do about it. We know that McKenna's old friend (and anyone else for that matter) can't screw with the Foundation's regenerator, or the Memory Repository that already has an older instance of McKenna on it, and a compromised/hacked soul gem wouldn't go unnoticed during debriefing. So how could a person's regeneration be delayed (but never completely stopped) reliably without messing with either the Regenerator or the Memory Repository? [Answer] Don't kill him. Rather than killing the Captain, almost kill him and drag him off to your underground base where you keep him alive enough that the regenerator will give an ERROR message whenever you try and respawn him, but not so much alive that he causes any trouble for you. See this [case study](https://www.youtube.com/watch?v=XCCR8D7C0PU). Edit: I have overlooked how the foundation can can create a double regardless of the state of the original. My answer works best if doubles are impossible. It also works if there is a reason the foundation is hesitant to create doubles. For example they are short-lived/evil/bureaucratic nightmare. [Answer] /You were never one of us. You are nothing but a usurper, a false idol. / There is a question as to the veracity of his recordings. Sometime in the past, his identity has been corrupted. It is not clear when or even how. It may be that recent recordings and then reincarnations have not been the individual who it is supposed to be. The imposter, if it is an imposter, is subtle. It may have laid in changes over time. Before bringing this possible imposter back to life, it will require a check of the code - a check against prior archived recordings of this code. The imposter, if there is an imposter, knew that this was a possibility and made its changes intending for the check to be difficult. It will be a process like checking accounts and financial records of a company looking for fraud. It will be laborious. There are not very many people qualified to do it. It will take a long time. And until it is done he will not be restored. [Answer] Report the Captain as MIA (missing in action), when he is actually dead, and hide the soul stone where it won't be found promptly, or destroy it (which would also destroy the memory of the events leading up to the Captain's betrayal, reducing the likelihood that the perpetrators will be caught and punished). Cases of MIA soldiers in the U.S. Korean and Vietnam Wars are often left open for decades until there is some confirmation and because there is a strong desire to repatriate the remains even at "unreasonable" expense. If repatriating a soul stone could actually add positive benefit in a respawned life, the incentive to keep cases open would be even stronger. If there is a desire not to have doubles, creating reasonable doubt regarding whether someone is dead and thus ready to be respawned (ideally with a recovered soul stone), or alive and just out of contact, would delay the Foundation from taking action to respawn that person. The Foundation may have a policy that is firmly established that someone can't be presumed death until ten or fifteen years have elapsed, perhaps based upon historical statistics on how often someone who is MIA (or their soul stone) is recovered, rather than immediately, as would happen if colleagues could make a convincing report that he is actually dead. Perhaps once death is presumed after ten years, there is another five years set aside to search for the dead person's soul stone (which might or might not conveniently turn up somewhere it could have been overlooked at the time of the disappearance, with the helpful hints of the survivors that they "suddenly" remember). This takes only a little lie quickly almost forgotten (since they haven't actually killed the Captain for good anyway), not any technical prowess or tinkering of any great degree. Even people who knowingly lie or create false identities about something that persists for long periods of time almost forget the truth themselves on a day to day basis and functionally start to think of the lie as the truth even if they know better in much the same way that someone who changes their name when they get married gets used to their new name being "true" in some sense even though they know they weren't born with it. Edgar Allen Poe and Leo Tolstoy were wrong in thinking that guilt about past wrongs weighs people down until they can't bear it. In real life, faking it until something is second nature is a very natural process. > > There is also a pretty infallible system to detect if a person is > still alive > > > If soul stones normally transmit a signal that someone is still alive that the perpetrators know wouldn't be present since the Captain is really dead, invent some way that enemy captors could suppress that signal in their prisoners of war. For example, maybe the signal can't escape deep mines and there is a widely credited rumor that POWs (prisoners of war) are often sent to the mines deep in the Earth to labor or to deep dungeons (and on rare occasions escape or are liberated, for example, when the war ends between the prisoner's home people and the people holding him) that would make a living MIA POW seem like they were dead based upon a lack of a soul stone signal. If this myth or half-truth is widely enough believed, no one would even bother to check if there was or wasn't a signal anymore, because that information wouldn't tell the Foundation what it needed to know. Another different myth that could foil the system for reliably determining that someone is still alive that is magical in nature could be some creature or spell caster who could cast a curse on someone that would "silence" their soul stone even though they were still living. A credible rumor that even one such person existed could bog up the respawning process when someone is MIA (even if they are not a POW). [Answer] ## Unleash a scavenger on his developing body. Provided that the Regenerator doesn't make the new body instantly, you can just put a scavenger next to him. Thinking him dead, it will start eating him. It doesn't affect the regeneration process, it just eats the new tissue as soon as it is created. ## Build a spawn prison. [![](https://i.stack.imgur.com/5OtTh.png)](https://i.stack.imgur.com/5OtTh.png) If your villain knows where the replacement body will spawn, he can build an inescapable trap around that spot. [Answer] Soul Gems aren't copies, but conduits Note: this answer is probably way out of line with the setting of the question, but as noted in my comment, very few options are left by the infallibility of the Regenerators. It turns out the Regenerators don't work at all in the way people have assumed all this time (or have been led to believe by the Foundation). The Soul gems don't contain minds, they contain the imprint needed to connect to the actual soul at a certain point in its hyperdimensional existence (including personality and memories that belong to that moment). The Soul Gem replaces a part of the brain's role, becoming the interface between the higher dimension where the soul resides and the physical world. This connection used to be severed on brain death, but now can be tenuously kept intact and restored by the Memory Repository and the Regenerators. McKenna's old friend and compatriots have "seen the light" and found out this most secret of secrets: All souls linked by Soul Gems are prevented from moving on to whatever afterlife there is. They have learned to "free" the soul, breaking the link between soul and Soul Gem in a (fatal) ascension ceremony. What they haven't learned yet is that the process only weakens the link and while it will break completely if left alone, it can be re-established over many years of activating the Soul Gem within the Memory Repository. Until that time however, any regrown body remains in a vegetative state. [Answer] Funny thing about old friends: they know stuff about you. All the old friend has to do is bring to light [Mckenna's past, like that time he got so high on magic mushrooms that he predicted the world would end in 2012](https://en.wikipedia.org/wiki/Terence_McKenna). Or something else just as shocking. If McKenna's employers suspect he's been playing both sides, or that he can defer to the other side if given motive and opportunity, they might want to wait before bringing McKenna back. They will put that respawn on hold until they can be sure of McKenna's loyalty, or at least wait until they can find some means to ensure his loyalty. Depending on how things go, they might even postpone that respawn until Kingdom come. --- By the way, the old friend's tale does not have to be true. It just has to be believable to whomever is in charge of respawns. [Answer] Already existing copy The villain managed to copy the data of McKenna and have a clone ready. When he kills the real McKenna, he triggers the birth of a new McKenna but with altered memories. The official regenerator will detect that McKenna is alive and when he comes back to the base, everyone will see that he is alive and well (and won't force a copy). What they don't know is that they just accepted a traitor back in their ranks. [Answer] ## Poison Pill Kill the Captain, leave his body, and flee just as the Captain's friends return while monologuing villainously. They collect the body, return it to the Regenerator, and the Captain is reborn, ready to fight again. *However* The enemy has tampered with the soul gem - replacing it, overwriting it, or corrupting it. Replacing: The Captain is an imposter in the Captain's body, and will turn on his 'allies' at the worst possible moment. Overwriting: The soul gem has been tampered with, and new memories have been added, and/or true memories have been deleted. The Captain no longer knows who are friends and who are enemies, with predictable results - he attacks allies and enables enemy actions. Corrupting: The Captain comes back as normal, but subtly changed. Each death / copy causes him to drift further from his original personality and his memories fade as the corruption takes deeper hold. Perhaps this is a slow version of replacing, and the Captain realizes with horror that his is a plant, destined to destroy his friends after the transformation is complete. In any cause, the damage is predicated on the idea that the soul gem appears to have worked properly, and the Regenerator presumably purges the old "copies" of a person following a successful re-birth. [Answer] Remote alteration of the stored mind(s). This does break your "cant mess with the memory repository" rule, but I think that limitation is there because you assumed messing with the pre-mission repository would require direct access to the repository. When you create a memory in a repository and/or soul stone you create a link between that repository and you that remains in effect after the copying. This could be the explanation of how they can determine you being alive or dead, as that link will be gone if you are dead. While you are outside of the range of making a solid copy of yourself, you are still in range enough for a very weak and faulty copy, messing with the existing one. The old friend will use this to create errors when the soulstone/repository is fed to the regenerator. You can clean it up ofcourse, but it could take up to 15 years if that person is dead and the repository is sufficiently scrambled. ]
[Question] [ A crone is a witch on the path to achieving godhood by stealing the life force of others through a dark ritual. The second stage on this path is the baba yaga, a point where the crone loses all traces of humanity and transforms into a higher life form, a reflection of her inner self. This creature is powerful, with natural abilities unique to itself, and can use them to create her own unique spells. At this stage, it can form a cult of individuals with a unique mindset of ascending to gods, but devoted to her. It can no longer operate openly due to its change in appearence, so must use its more human witch emissaries to act on its behalf.These followers are taught the kind of magic created by the baba yaga and are given similiar abilities unique to her craft by it, and go out into the world to spread it's influence in various ways, through war or business, etc. They are usually small in number and operate independently, but may come together to serve a bigger purpose. The system works as a pyramid scheme, in which a member is responsible for recruiting other members, strengthening the numbers of the organization. However, these witches are also capable of performing this dark ritual whenever they have the chance, and are likely to do so. Understanding this, the baba yaga wants to ensure that none of them get more power faster than her. Whenever a witch performs this ritual on an individual, the largest portion of the energy gained should be given to her. The spell can be done by themselves but this is much more difficult and dangerous. Therefore, this ritual is normally done in teams of up to five members, called a cell. The power gained from the ritual, say 25%, is shared among the cell, with the majority 75 % going to the baba yaga. The more cells have been established among her members, the more power the baba yaga gains through their efforts. Regardless of whether the ritual is done singly or with group effort, it ensures that she reaches her goals faster, and prevents any one individual from surpassing her in power. This is a cutthroat operation where each witch is out to achieve power for themselves, and distrust and treachery is commonplace. It is similar to the Sith with the master apprentice concept, but without the rule of two to keep it in "check". Expecting these ruthless individuals to give up a major portion of power to the top boss willingly is unrealistic. I need this system to benefit the maximum amount of people as possible while keeping the most senior members more powerful than their underlings. I also need the group to not implode as a whole due to betrayal. What procedures would ensure that this system continues with consistency despite all the backstabbing and treachery? [Answer] These rituals require material components. What your witch needs is a monopoly of those components. She may start a brand - Witchlife - and sell those components directly to other witches, who then can resell those components to other witches for a profit. By joining her network, the reselling witches can make enough of a living to quit their jobs and become their own bosses. It works like this: non registered witches buy the products at their full price, but registered witches get a discount on every purchase based on the volume of products they acquire, along with a badge: * Up to 3,999 units a month: 15% discount and a title of Witchlife representative; * 4,000 to 9,999 units a month: 25% discount and the title of Witchlife consultant; * 10,000 to 24,999 units a month: 35% discount and title title of Witchlife doctor, along with the right to start her own organization; * 25,000+ units a month: 50% discount and the title of Witchlife director. Further amounts grant titles such as chief, president etc. No further discounts are given, but you get rotaltyes over your organization's profits. An organization is a chain of witches who register each other. When you register a witch under you, it is to your interest that they sell magical components to other witches. For example, you can hardly sell components to 10,000 witches by yourself. But once you become a director, for example, you can sell to ten doctors, and with a 50% discount your profit is practically 100%. The doctors under you will then sell to a hundred consultants and get their 35% share of sales, and those consultants will sell to representatives and non registered witches and get their 25% share. If you are a chief or higher you get 5% royalties over all those units and are eligible for rewards such as a cruise to Avalon on a flying caravel, jewelry embroidered with the Witchlife logo and an article about you on the monthly Witchlife Almanac! Witchlife products are usable in the Baba Yaga ritual and work by balancing your aura. All you need to do is replace one or two meals a day if you want to lose mana, or eat them along your meals, if you wish to gain mana. The products are safe and backed by Hogwarts. You can trust Witchlife because we have and Gandalf on our payroll, doing research to deliver state-of-the-black-arts magical products to you. If you are interested, I just happen to have an opening for a new representative on my organization. Just write your sigil on this contract and you can start buying from me today. Just give me your firstborn child for a couple thousand units in products, and in a just a few short months you may have enough firstborn children from clients to retire. Trust me! Join Witchlife today! [Answer] Simple Deception, Concealment, and Misdirection Claim that the commission must be paid (true) to some other super-being instead of the baba yaga (false). If needed, claim that the baba yaga is collecting on behalf of the super-being, who will later drain the power from her. She should appear anxious and stressed before her meetings with the imaginary, unforgiving boss. She should seem relieved and harried afterward. This creates a whole new level of mystery and threat that uppity underlings must penetrate before they dare to topple her. Heighten the mystery with plain old flimflam. Identify underlings who try to penetrate the mysteries as dangerous, and begin a whole new path of "training and preparation" for each that ends in their inevitable destruction without leaving the rest of the organization any wiser. [Answer] > > These followers are taught the kind of magic created by the baba yaga > > > The magic created by the baba yaga has a sort of signature, which is specific to the baba yaga. When casting the magic the signature cannot be skipped, else the magic won't work. The signature also ensure that for any power gained by that magic, the due share is delivered to the baba yaga. This will > > ensure that this practice continues with consistency despite all the backstabbing and treachery > > > the only workaround being not using the magic. [Answer] The usual empowerment ritual requires 2 components: A "donor" beneath you to push you up (like stairs or a ladder to climb), but also a "patron" above you, to pull you up (like a rope hanging down). This is required to keep the ascension stable As such, the ritual is not even possible without diverting power to the (or at least a) Baba Yaga - and attempting to do so will, in the best case, result in the power dissipating and being lost, or in the worst case cause the practitioner to redecorate their ritual room in a fresh coat of "visceral red" There does exist an older, harder, less efficient, original and more dangerous form of the ritual that does not require the "higher power" to assist, which the elder Baba Yagas try to keep this under wraps (so as to remain at the top of the food chain). This does not always prevent their more ambitious or intelligent subordinates from discovering or recreating the ritual - but the increased chance of critical failure usually settles the matter without a need for too much interference. [Answer] Divide and conquer is the answer. The baba yaga can feel how much power anyone gathered when she meets them, and thus determine if proper tribute has been paid. Power can also not be gathered up too quickly Since she is the most powerful individual to start out with, no one wants to pick an open fight, since that gets them destroyed. Similarly her underlings keep their underlings in check. Of course everyone wants to get to the top spot, but nobody wants to be caught cheating. Backstabbing will happen, but everyone will want plausible deniability instead of flaunting the rule to pay proper tribute. [Answer] When a witch joins a coven, a link is created between the master of the coven, and the witch. This link allows power to be transferred between the two individuals, though always under the masters control. So usually the master takes whatever they need for their magic, and only grants "boons" to their servants if they ask nicely and provide a very, very good reason (probably something that would benefit the whole coven a lot). Such a system would grant increased power the higher you get in the hierarchy, creating ever more impressive acts of magic to draw new followers to the coven. It would act as a form of protection for the master, as any servants can't rebel without loosing access to most of their power. this should create a system with rich potential for intrigue, and infighting between equal witches (at roughly the same level) but almost never between master and servant. ]
[Question] [ Simple question, hopefully not broad. This is the 21st century, everything that we have. Technology to make cars, planes, trains, boats, all of that stuff. But then, in this world, everybody is a winged-human, or angels. So my question is: What would a civilization of angels use for transportation, and why if they could just fly to places? [Answer] We have transportation because of our flimsy legs, and convenience. Would you like to walk one mile for 15 minutes, or drive the same distance under a minute? I believe this will be the same concept for winged humans. If it's more convenience for them to use transportation, they will do so. In this case, planes will definitely still be viable for long distance travels to other countries. But we don't just use transportation to get one person from A to B. We use it to transport goods as well. Would a winged human fly all the way to the store and back while carrying groceries? Probably not. Hence, huge boats carrying goods from one country to another is still going to be used. Luxury cruises will still be there. Trucks delivering goods from warehouse to the stores is still required. And cars will help winged humans from bringing back groceries or furniture from the store to their homes. I think that infrastructure would be the biggest change for a civilization of winged humans. Perhaps there's a lot more tall buildings, as they're easily accessible for one that can fly all the time. Doors at the ground is no longer the entrance, perhaps a lobby in the middle of a tall skyscraper would make more sense. But I'm getting off-topic here. In short: Yes, transportation is still going to be used by winged humans due to convenience. [Answer] Humans can walk from place A to place B, so why do we need land transportation? Movement is tiring, energy consuming. True flight would be quicker, but still laziness drives inventions. Land The main reason these angels would have for traveling over land would be transport of goods. Therefore, most of their land based vehicles would develop in that direction. They'd develop means that are similar to ours: cattle drawn carriages, then the emergence of motor vehicles, with trains and trucks being the focus. Alongside that things that make short distance travel possible would also be favorable, as most long distance travel will be quicker through flight. The human equivalent of bicycles will not happen as bikes do not seem like a comfortable travel option with the wind wreaking havoc on your wings. I assume the first form of passenger travel vehicles will be sort of like tricycles, with a windshield up front. They'll not be a prevalent form of transport though. Cars will come around eventually, but these will be decrepit, roomy machines compared to what we have. Water Water transports will develop in parallel to how ships developed in real world. The water bodies will remain the easiest form of transporting goods across long distances. Boats and ships will develop as such. Ships designed to carry passengers will also be equally prevalent, as they offer the option to distant lands in comfort. Unpredictable weather and lack of resting grounds will convince even the most hard headed angels that he cannot simply fly to the distant lands across the sea. Flight I believe this is where the technology will be most alien. The first form of air transport will most likely not travel. While flying itself is tiring, taking off after landing takes huge bursts of energy. Angels will prefer to use higher grounds as take off points so they can just drop and catch the air instead of producing vertical lift. But finding a high ground to rest may not always be possible. The first form of aerial transports would be these cluster of hot air balloons that are rooted in a fixed position. These will act as land marks for watering spots. The angels land on them, and these balloons then transport the angel to the town under them. Once his/her stay is over, the balloon lifts them up again, so they may take off. While humans also started out with hot air balloons, the angels will take the balloon technology further, and not go the typical airplane route. I cannot imagine a being capable of flight willing to be strapped down to a metal cylinder with bad air-service to fly. I imagine Zeppelins would be more prominent, some hosting on-the-air tavern service for the weary travelers, or offering services to take them a certain distance while they rest their wings. Airplanes will eventually develop, with the focus again being on transportation of goods. But this change will come around much slower than with humans, due to the tangent it took, and probably not be as advanced as our 21st century equivalent. [Answer] 1980's cartoons gave us the answer. They would use horses: ![I always wondered if the horse would fall should Venger dismount in air](https://i.stack.imgur.com/bR52M.jpg) No reason other than the Rule of Cool. There is biblical precedent for this. The four horde en of the apocalypse happen to be angels, as far as I know. [Answer] You could make it a class system. I'd imagine everyone flying at once would look like Woodstock. So the skies could be reserved for arch-angels or other figures of authority while the lower choir could be restricted to teleportation hubs ]
[Question] [ My story is set in the future where space travel is cheap and humanity has colonized Mars and some parts of the asteroid belt. Asteroid colonies can grow their own staple food, but crops that require pollination, like fruits, are imported from Earth and Mars because it's cheaper than growing them on the colonies. The story starts when the prices of imported crops rise to the point where the colonists start to consider growing their own fruits. The colonists have had some success, but because fruit plants has to be pollinated by hand (no bees in space), most of these attempts are small scale. The protagonist of the story is a thief who creates and uses bee-like robots to aid her in stealing things. She then discovers that her bee robot technology can be used for more productive things, like pollinating fruit plants cheaply and quickly, enabling mass production of fruits. The thing is, shouldn't this kind of technology be perfected and commonplace before we reach this level of space travel? Even now, people around the world are trying to develop robotic artificial pollinators, because the bees are going extinct or something. How can I explain why this artificial pollination technology didn't make it to the asteroid colonies? [Answer] > > How can I explain why this artificial pollination technology didn't make it to the asteroid colonies? > > > Half of the answer is in the question itself - importing food is cheaper than growing it in the asteroids, so there was never incentive to pursue self-sustainability. The other half is... Why is it expensive to pollinate your own food in the asteroids? Many factors, one of them being that pollination is only part of the equation. If you are in an asteroid, you have a lot other challenges between you and your harvest. * The water cycle. Earth has a lot of water that is easily and readily available. On an asteroid, you have to harvest it, treat it, clean it... Largely without the help of mother nature and her water cycle. Clean water in the asteroid belt is expensive. * Arable land. You don't have it. Your crops are grown in artificial labs. Even the real estate for those comes at a premium. On Earth you can just buy a plot somewhere far from cities and have a go at it, there is lots of available land. But consider this for space farers: [![Largest asteroids](https://i.stack.imgur.com/tumri.png)](https://i.stack.imgur.com/tumri.png) Source: <https://en.wikipedia.org/wiki/4_Vesta> * Energy. Even if you are using direct sunlight to grow your plants, you will still use a lot of energy to keep the water flowing, to keep the pollinators going, to monitor the growth of the plants etc. That energy could otherwise be used for stuff like keeping every other system going, so plants compete with people for energy. * Waste recycling. Once people eat those plants, they will become... er... [a very poor quality fertilizer](https://en.wikipedia.org/wiki/Night_soil). If you are not bringing in new materials from outside, this is the prime candidate to be the mass source for new plants. But this requires A LOT OF WORK, from chemical treatment (because human waste is far from the best fertilizer) to the optimal application of that in a hydroponic farm. Really... What your thief did with pollination is just one variable in a very long equation. She just made the whole process slightly cheaper. It will take the collaborative work of many other people in other fields to make space food growing economically feasible. But who knows? Maybe she solved the last problem left unsolved, so kudos to her. [Answer] Because there was no profit in it: The companies sponsoring the colonies had planned on making their money back by selling them food. The recent price-hikes may not even reflect market conditions back on Earth! Artificial pollination could be a well-used technology on Earth, but the patent holders are either being paid not to license the neccessary technology to colonies, or are the import companies themselves. Your thief has managed to design or acquire technology that fulfils a similar function to some of these patents, but with a sufficiently different method of operation so as to fall outside those patents. (Such as LEDs in a world where incandecent filament lightbulbs are tightly controlled, or a [Mechanical TV](https://en.wikipedia.org/wiki/Mechanical_television) vs a [CRT TV](https://en.wikipedia.org/wiki/Cathode_ray_tube) or [flat panel display](https://en.wikipedia.org/wiki/Flat_panel_display) - not neccessarily 'better' or 'worse', but different.) {EDIT} Considerations: Since the thief's drones were originally designed for help in their "extra-legal activities", they are probably optimised for things like silence and stealth over speed, they are not normally equipped with anything suitable for collecting/distributing pollen efficiently, and so on. On the other hand, multi-spectrum scanners (IR/UV/etc) to help with "liberating" objects would also be useful to distinguish between plants that look the same to humans but different to insects [Answer] ## Bees are cheap Actually bees are nearly free. (Also, some bees, but not always the ones used for industrial crop pollination, make a product you can sell as a honey bonus.) So yes, currently people are trying to make robots that do bees’ work, but I believe it is only for show. Who seriously wants to pay to develop, construct and maintain thousands of robots while the bees are doing it for free? Flying robots are expensive, but bee-robots are so even more because: * They need to be very small to access the flower * They need to be very light and gentle to avoid blowing the flower * They need to be intelligent to correctly identify the flowers * They need to collaborate, to avoid in-air crashes and so on * You need a large installation to charge the batteries * You need energy to make them fly and think * You need to repair them or buy new ones regularly And you can multiply all these because: * You need thousands of them to do the job I guess the cost of the robots made it cheaper to import the apples. --- But, then, why not import bees? well,... ## Insect are dangerous for colonies In colonies that are in hostile environment, insects of all types represent a threat: * They enter some air recycling pump and clog it –> death of the colony * They dig through a sheet of insulating material -> death of the colony * They contaminate the food reserve -> death of the colony * They bite the wrong person and he/she is allergic -> death of the colony * They spread some disease -> death of the colony * An operator tries to smash a mosquito that just landed on the self-destruct button -> yeah, you guessed! * … Basically, the more isolated from backup, and the more hostile to human life is the surrounding environment, the less you want randomness in your colony. So, you don’t want any little creature that can randomly create havoc in your colony. You are going to spray a lot of insecticide in your colony and vessels coming in, and bees are especially sensible to that. You don’t have bees, and other insects, simply because they are dangerous in a controlled environment and you don’t want them. It’s cheaper to import apples than to import replacements parts due to insect damage. --- (As a side note, I would like to stress that, for the exact same reasons, thinking that bees' dying out is not a problem because of technology is totally nonsensical) [Answer] There are many self-pollinating and wind-pollinating varieties of fruits and vegetables, I don't see why these wouldn't be selected as crops for feeding a colony. The technology could mean a greater variety of fruits and vegetables are available and would allow a colony with the robo-pollinators to compete (economically) with Earth and Mars grown foods being sold to other colonies. [Answer] A pollinating drone needs to be very small to access the flower, and small drones are very susceptible to wind. On a windy Earth it would be very difficult or impossible to perform pollination with bee-like robots, but in a space habitat there is no natural wind. This is why the tech was never developed on Earth, much easier to take steps to keep the bees alive. [Answer] [Colony collapse](https://en.wikipedia.org/wiki/Colony_collapse_disorder) on Earth is a very real problem. It would be the same effect on an asteroid colony where no bees exist. An artificial pollinator is required. The research is already being done. Apparently, protecting the real bees is not cost effective but selling micro-drones is. From there, it is just a matter of programming the drones. One reason that someone would not want to provide pollinators would be the aspect of controlling the population. Removing self-reliance is a great control mechanism. [![enter image description here](https://i.stack.imgur.com/vQ8Cn.jpg)](https://i.stack.imgur.com/vQ8Cn.jpg) [Answer] Originally the space settlers tried to bring bee hives with them. Was a bit of a trying journey for the settlers whenever the hive wanted to swarm. They had trouble getting the bees to survive the trip and those that did survive couldnt adapt to the alien environment. Being endangered, it was also very expensive. In the mean time, after many failed attempts at transporting live bees and failing to adapt Earth-based alternatives, they had managed to develop a hand pollination system. They kept wanting to develop an artifical system, as humans are naturally lazy at these repetitive tasks. However, piped pollen sprayed on the crops kept blocking the pipes and causing expensive delays and repairs. Pollen is sticky. Artificial drones amd other Earth based robotic pollinators had magnetic/alien planetary interference which kept preventing the drones from communicating effectively with the domes artificial environment control system (AECS). They need a better acronym. This means that even though the drone systems work on Earth, the systems just are not compatible in an alien offworld environment. AECS has total control of the entire settlement and even controls security. For security purposes all domed and inhabited areas are scanned for unexpected metal/plastic visitors. Many thieves have thought to use drones before. What your protagonist has done, is actually develop a shielding for her drones which prevent them from being scanned by security. She used some alien mineral or highly clever handwave computer trick to provide a shield coating to her tiny friends to bypass AECS security systems. The drones communicate amongst themselves. Instead of providing feedback on their position to a central server and being controlled by AECS, the drones are receiving feedback from amongst themselves and do not need outside control. The shielding from the security system has an unintended side effect of negating the planetary interference that had previously hindered pollination attempts. Your protagonist has developed a proto hive mind drone based AI. She provides them input parameters of what she requires and they then go off and do their own thing without needing constant movement reports from AECS (which is what all previous attempts had attempted). As they no longer need to report their position and the shielding from the security system preventing other planetary interference, they succeed in stealing trinkets for her, and later making her quadrillions of credits when she commercialises her product. What the Martian colonies look like after the Drones realise sentience is another story. ]
[Question] [ I mean, could enough of the Earth be flooded enough that most of the surface would be uninhabitable? Would there be enough water in the glaciers/ice caps etc for this to happen? Could any sources from outside the Earth contribute to this? I'm looking more for 'realistic' scenarios than, say, aliens or magic... Edit: as in the parts of the Earth that are currently not already under water... [Answer] A controversial theory suggests that there is a vast quantity of water trapped in the Earth's mantle. If just 1% of the mass of the transition zone of the mantle was composed of water, that would be about 3 times the amount of water in the oceans today. Most was trapped there during the formation of the Earth, while some is pulled down through the subduction zones of the Earth's crust The hydrological cycle would have to be interrupted somehow to allow that water to percolate out of the mantle. Given the massive pressures and temperatures found at that depth, the water would probably return to the surface in the form of high pressure steam blasted out through volcanos and undersea vents. This injection of high energy steam into the hydrosphere and atmosphere would create rather alarming changes to the global environment, and a lot of water from the oceans would be evaporated along with the new water being introduced as steam, filling the atmosphere with a hot mist which will eventually condense into a massive amount of rain. One other possible effect of the water being extracted from the mantle is that the natural lubrication effect of water trapped in these rocks will cease, making plate tectonics much more difficult. Plates locked together will have less ability to move or deform to release stress, causing much more massive earthquakes and huge tsunamis in the now global ocean. (Tsunamis breaking over the submerged Rockies or Himalayas will be spectacular). [Answer] Not easily. All the ice melting is not enough to flood all the dry land on Earth. [National Geographic has some nice maps](http://ngm.nationalgeographic.com/2013/09/rising-seas/if-ice-melted-map) predicting how that would look. ![enter image description here](https://i.stack.imgur.com/Y8Tok.jpg) Magic would be required to flood the entire surface of the Earth. Similar to what happens in the mythological story of Noah, recently a blockbuster movie. For a science explanation, perhaps the solar system passes through a dense nebula of water ice. It would take hundreds of years for enough water to accumulate, and there would be other more severe problems, so it's not a very dramatic possibility. [Thucydides provides an excellent alternative](https://worldbuilding.stackexchange.com/a/18555/3202) for the source the water, the water of crystallization trapped in some very abundant minerals in the Earth's mantle. If enough of the ringwoodite went through dehydration melting, its water would be released, possibly making its way to the surface. Otherwise you'll need to level out all the land. If Earth were a smooth sphere, the water would be about a mile deep all around. This is less feasible than aliens hitting us with a planetary super-soaker though. [Answer] If all of the ice on Earth melted, the sea level would rise by a bit over 200 feet. While most of the current landmass of Earth is above this level, significant portions of the Earth's population live in coastal areas that are below it. Around a billion people would be displaced if all of the ice melted. If you're curious which parts of the Earth would be most affected, National Geographic created this [nifty series of maps](http://ngm.nationalgeographic.com/2013/09/rising-seas/if-ice-melted-map) showing the new coastlines. You could bring the new water in from space, of course. In order to cover up more than half of the land area in the US, you'll need to cover the Earth with another 3km of water, roughly. This corresponds to around 1.53 billion cubic kilometers of water. A sphere of this much water would be a bit over 700km in radius, which is bigger than any asteroid in the solar system, but smaller than Pluto. The danger in getting water this way is that anything coming from space will come at a high velocity. Aside from the global flooding, a series of massive tidal waves will probably scour all of the surfaces of the Earth, and debris and steam will block out the sun, probably for several years. Almost all life on Earth will perish. The kinetic energy released will turn to heat, which will melt the ice caps and raise the sea level by an additional 200 feet. [Answer] If you want to avoid magic, maybe try comets. Some undiscovered comets could skim past Earth in a (very) precise manner, losing water. [Comets are icy](http://en.wikipedia.org/wiki/Comet), and if they passed just close enough to aerobrake and continue past Earth, they would lose a lot of water into our atmosphere. That would require a lot of work and precision, and a lot of small comets, though, so maybe you will need the aliens afterall. [Answer] I assume you mean, "using only water presently on the Earth". If we can import unlimited amounts of water, then of course the answer is "yes". No one knows exactly how much water is underground, but estimates are that it's a very small amount compared to the amount in the oceans. I came across some numbers years ago, (quoting from my own book here, is that cheating?) 97% of the world's water is in the oceans, 2% in ice caps and glaciers, 1% underground, 0.02% in fresh water rivers and lakes. So as others have said, melting the ice gaps and bringing up all the underground water wouldn't increase the level of the oceans very much, not enough to cover all the land. On the other hand, I think the common theory among creationists today is that before Noah's Flood the Earth was more nearly spherical, i.e. the mountains weren't as high nor the ocean trenches as deep. If you think about it for a moment, if the Earth was a perfect sphere, it wouldn't take very much water at all to cover it (relatively, any way). Do the arithmetic and if the Earth was a perfect sphere, the amount of water in the oceans today would cover it to a depth of 1.7 miles. So the (logically) easiest scenario to flood the Earth is: level the mountains and fill in the ocean trenches. If the highest mountains and the deepest trenches were about 1/4 what they are today, the entire world would be under water. [Answer] Based on some rough calculations, if we wanted to cover all the land on the earth with water up and above the peak of Mt. Everest, we would require at most 200,000 cubic miles of water. Based on Galileo Probe data, Jupiter's moon Europa has about 933,000 cubic miles of water on/beneath its surface. (For reference, a cubic mile of water is about how much flows over Niagara Falls in a month.) Is it feasible to remove this water from Europa and place it on Earth? Randall Munroe answered a similar question here -> <http://what-if.xkcd.com/143/> Using some rough potential energy calculations, we can find that the energy required to lift 200,000 cubic miles of water out of Europa/Jupiter's gravity well would be on the order of 10^20 Joules, or about 10,000 Terrawatt-Hours. For comparison, the entire planetary electric generation of the Earth in 2012 was about 22,000 Terrawatt-Hours. Obviously this is a wildly optimistic back-of-the-envelope calculation, but depending on how much you're willing to suspend disbelief, it could be done by a sufficiently advanced civilization with access to enough power. ]
[Question] [ I want to have a setting for a thing I am doing set in a world with a three-way space race between countries X, Y, and Z. Each country has a space program roughly on par with the 1960s US and [USSR](https://en.wikipedia.org/wiki/Soviet_Union). Detente between any two of the countries is very rare. Having this in mind, I wanted to establish a good reason and way for how this setup could happen/what setting would be needed for this space race, in order to keep the story internally consistent. My first thought for having this happening was a three-way cold war, but [certain questions](https://worldbuilding.stackexchange.com/questions/196006/what-could-have-caused-a-three-way-cold-war) say that the arrangement would be too unstable. I want to know what setup for three countries x, y, and z there could be to allow for them to have a space race where it is 1v1v1, meaning they don't become allies/gang up on one/make it a 2v1, and remain at least a little hostile towards both of their respective enemies. [Answer] No nukes, and it probably still won't work The key problem here is that space assets are strategic assets. Nation states can accept losses of tactical assets - a certain number of military personnel, vehicles, aircraft and watercraft will be lost in training or even barracks duty - but the loss of a strategic asset weakens its entire military posture. Which means that border skirmishes can occur in which a couple or even a [couple of dozen people are killed](https://en.wikipedia.org/wiki/2020%E2%80%932021_China%E2%80%93India_skirmishes) and the respective countries' populations will be angry but escalation to all-out war may not occur. Strategic assets are different. Satellites provide a number of huge advantages to a nation state: 1. Communications. Essential for command and control, satellites make communication over large distances, especially with mobile units such as naval vessesls, much easier than the alternatives. Command and control rely on a solid communications network - if someone targets your comsats then they are targeting your ability to coordinate your military, which is a strong indication that they are about to launch an attack. Assuming civilian use, then an attack on comsats is also an attack on your economy. 2. Reconaissance and early warning. Especially since the advent of ballistic missiles, satellites are typically the first option for detecting the launch of long-range missiles. If another nation starts taking out your early warning network, it is a strong indication that their missiles will not be far behind. 3. Weather prediction. The ability to accurately forecast the weather is vital for both military and civilian activities - history is full of disasters that could have been averted or lessened with greater foreknowledge of the weather. If someone starts taking out your weather satellites, they are targeting both your military and your economy. The three types of satellites listed above are strategic assets because the loss of them degrades the entire nations' military and/or economy. They are also very expensive to launch, especially in the days before cubesats, making their loss a significant portion of the national and/or military budget. Attacking another nations' satellites is equivalent to attacking their national power grid, or mining their harbours, or spreading bioweapons through their crops - it is an act of war that will trigger a hot war. Especially if nuclear weapons exist, attacking comsats or early warning satellites is a primary indicator of a nuclear first strike with ICBMs. (Obviously, any country that can put assets into space can put them not-quite-into-space and build a ballistic missile.) So, an attack on space assets is likely to lead straight to nuclear war. "Ah," you say, "but what if you only target the other country's equivalent of the [Hubble Space Telescope](https://en.wikipedia.org/wiki/Hubble_Space_Telescope)? That is not a strategic asset the loss of which will result in nuclear armageddon." Well, maybe, but why? You may come out ahead monetarily - the Hubble-killer probably costs less than its target - but you are just showing that your nation is a group of vandals who may target the Great Pyramid and the Louvre Museum next. This will trigger exactly what is specified as being undesirable - the other nations will get together to stomp flat the vandal who is trying to burn the house down. At a minimum the nation targeted will stop building research satellites and switch to hunter-killers until they control Earth-equivalent orbit. Given that there is no stealth in space, it is not even feasible to try to false-flag attacks and blame someone else. Where does that leave us? In order to have skirmishes in space that do not lead to full-blown war - regardless of the number of players - the following conditions must be met: 1. Space travel must be cheaper than it is on Earth, cheap enough that all sides can afford to send up combat units that will be lost through attrition. 2. There must be no weapons of mass destruction (almost impossible) or international rules that somehow make all nations completely confident that such would not be used by any of the other nations. I have no idea how that might occur. 3. All nations are willing to live without satellite communications in order to keep Earth orbit an active war zone. Ditto for weather satellites. 4. All nations with space assets gained capabilities at the same times and in the same quantities - otherwise one would have surged their forces forward and taken control of orbit. This situation somehow persists for decades. Good luck developing the idea, but it seems implausible to me. Espionage in space is totally plausible, but once conflict starts, I cannot see three or even two equal-ish sides staying in the game, there will either be one or none (see [Kessler Syndrome](https://en.wikipedia.org/wiki/Kessler_syndrome)). [Answer] ## On Equilibria A 3-way political equilibrium isn't actually a sustainable equilibrium any more than a 2-way political equilibrium is sustainable. Such systems don't remain stable without feedback loops to regulate and moderate function. You only need them to be "stable" over a period of time. That would be more believable. A decaying but formerly glorious empire that had 2 rebellious satellites coming into power as the empire faded might be believable. That may be a basis for a 20-30 year period of "stability". You could even then posit some type of a rebirth or rejuvenation to the old empire at some point in it's decline, that would lead it back onto the stage. The primary problem with human societies maintaining such equilibria is that there are 3-4 various large scale factors that can cause those societies to diverge rapidly in terms of effective power. Technological advancement, resource access, geographical advantages, and cultural norms and the impact on the population size and education. How do you put them into an equilibrium where they are at odds with each other, but those other 4 factors are somehow different, because they will be, but stable, and stable in 3 directions? That's really difficult. The chaos of large scale social, knowledge driven human-like societies is going to make a long-term stability unlikely. You will have to continually expect a falling out of balance, and then solve the disequilibrium through some believable means. The means you use will have to fit the solution to believable narratives around human behavior and the laws of nature. ## Is It Vital? Is this political setting the point of the story? This setting of 3 political entities in some type of war-like equilibrium is either a device or a setting. Either your are using it to play out some thoughts about how things work, and explore potentials, or it's a backdrop to some other story within which your primary exploration/narrative will play out. It might be useful to get clear on that, and see if that setting is so vital and necessary, or if another setting would suffice. If it is vital, and it's not the primary point of the narrative, perhaps you don't have to make it hyper-real and believable. Perhaps the reader will suspend critique in order to take the fantastical journey with you in order to engage the primary narrative and the exploration of potential your narrative presents for consideration. ## Seeking an Answer... I would look for complex systems where you have a triadic as opposed to a dyadic equilibrium, and then try to figure out how to transpose that equilibrium into the socioeconomic and political realm. I've never thought about looking for such an equilibrium, but it's possible that such exist. It's more likely that you will find an dyadic equilibrium where you have a 3rd party that is technically in a relationship to the dyad, rather than in a balanced equilibrium with the other two. Off the top of my head, a predator-prey relationship is a dyadic relationship, the scavenger relationship is a third to the dyad. Maybe... Anyways, just a thought about how to approach seeking a solution to the problem posed. [Answer] Unreliable space communication, space is dangerous and threat of MAD on Earth In most of history, where there are proxy-conflicts (which is essentially what you are talking about here) - there needs to be an element of deniability. "Oh, these mercenary groups just butchered an entire village in location? Well, we didn't order such an attack! No we don't fund these groups! We only pay this reputable company any funds directly - if they then subcontracted out, we wouldn't have the same degree of control" In short - if you want to have what happens in space to have little to no impact in what happens on the ground - you need a way for all sides to have enough plausible deniability: * Space combatants went rogue * They were fired on first * Strict stand-down orders were sent * It wasn't us, it was an unfortunate accident * We lost contact with the crew and can't regain comms. This however, is not sufficient - because why would the other 2 superpowers have a vested interest in going along with various lies? You need the threat of a greater conflict happening on earth to stop it from spilling over. You could do this via the old MAD strategy (whoever attacks first would get the other 2 retaliate - not talking an alliance, more like kicking an enemy when they are distracted). There's also no reason why you couldn't have a 4th super-power on the earth that has no interest in Space exploration (due to cultural reasons) but would act very much like an Umpire if anything started to go down on Earth. [Answer] * A three-way Cold War may be unstable, especially if it goes as violent as you describe, but it is plausible enough if you want to have it. * Space becomes something like a limited regional war in the real history. Soviet pilots operated Soviet MiGs over Korea against American forces, yet peace held along the Iron Curtain in Europe. That was because both sides came to a tacit agreement how the war would be fought -- no bombing across the Yalu, a few Soviet 'volunteers' instead of the whole Red Army. * Certain mutually understood and accepted limitations hold in space. No bombing of surface launch facilities, no attacks on 'clearly understood' major dual-use stations, but orbital fighters and smaller, military-use stations are fair game. 'Dock an engine and deorbit' sounds impractical, by the way. Direct-ascent ASAT, co-orbital killer sats, debris clouds on intersecting orbits ... say A has a gun platform on some orbit, and B launches a mission which leaves a spent rocket stage on an orbit that will 'intersect' with the gun platform in a couple of weeks. They might even publish a warning, and force the gun platform to expend maneuvering fuel to get out of the way. (The spent stage is no longer maneuverable, of course.) Do that often enough, and the gun platform runs out of fuel. [Answer] This sort of reminds me of the game Metal Fatigue. Where corporations are what run the place, not governments. Which gives me the idea, what if this space race was not between governments, but between corporations. As corporations, an expensive war would hurt their share prices, hurt their shareholders, etc. So any skirmish would never break out into real open conflicts. You would have acts of sabotage only. And since these are corporations that are in theory not attached to the government (they probably are but plausible deniability) their space fighting wouldn't actually trigger a war. It would be like if the big oil companies started attacking each others tankers. This of course leads to mercenaries, privateers, etc. You have lots of real world examples to draw on. [Answer] ## Creating the three-body problem George Orwell based the three competing nations in 1984 on his earlier thoughts with regards to nuclear weapons as detailed in [You and the Atom Bomb](https://www.orwellfoundation.com/the-orwell-foundation/orwell/essays-and-other-works/you-and-the-atom-bomb/). Namely that the complexity of such weapons ensured that massive states would dominate as opposed to a scenario where small groups can pose huge threats. Of course, nuclear weapons introduce the problem that the world is less stable as one small event can lead to the destruction of entire nations or the human population itself. We need to have a situation where the three nations are in a military stalemate in which none of the participants can successfully invade or permanently damage either of their rivals. One way to achieve this is to have the states separated by large oceans, and wield devastating short-range weaponry that can't be easily projected with no real alternatives. * Each state occupies a continent or archipelago with no land borders to a competing state. * A new sort of weapon is developed, such as a pure-energy Beam, that is devastating and extremely precise, but requires large and costly installations to operate. It has limited range. * The Beam can shoot down ICBMs and missile-loaded aircraft without cost or trouble, making traditional nukes only effective in skirmishes outside of the states. * Conventional naval invasion is all but impossible because large vessels, aircraft carriers, and boarding craft are all easily dispatched by land-based defensive Beam installations that cover every nook and cranny of the coastline. * Vessels can host Beams, but these portable installations are not large enough to reach land-based Beams before being vaporized. ## Space: the final vaporizing frontier The three states engage in a ruthless space race because it is the only way to project the Beam where it can level a rival nation. * Due to the meteorological makeup of the planet, the efficiency of solar power shoots up dramatically above the world's equivalent of the Kármán line. It is possible to power up a large scale Beam with light but nonetheless highly advanced solar installations that would be ineffective on the surface * The lack of atmosphere allows the Beam to reach critical mass otherwise impossible on the surface, which then removes the range constraint of the weapon allowing it to level all land-based Beam support from the vantage point of a large enough space installation. Some of you may fondly remember the GDI Ion Cannon from back in the day. * The three states are constantly trying to prevent the other two from building such a Critical Mass Station somewhere in orbit: if a state were to build a CMS-precursor and manage to power it up with a basic Beam, it would be game over for the other two as it would have gained an impregnable foothold in space and eventually the means to dominate by projecting Beam firepower. * The planet's atmosphere is constantly abuzz with firefights as the states try to navigate around their enemies and build up their own station. No skirmish leads to MAD as the states are stuck in a stalemate until one of them builds the end-game Beam station. [Answer] Let's think of something that doesn't involve war The Space Race here on Earth was driven by the cold war between the U.S. and U.S.S.R. Among other things, it was an important (and this is important) propaganda tool between the two nations as they jostled for dominance as the world's "super powers." Frankly, I suspect if you asked people not in either country back in the mid-1960s what they thought of the curious ballet the U.S. and U.S.S.R. were dancing, most would say something that translated to either "it scares the snot out of me" or "I wish those two would get over themselves." But let's move on. It's possible to have an N-way cold war: it requires similar technological capabilities, manufacturing capabilities, espionage capabilities, and enough other countries to act as proxies for the fighting. But the more people you add to that stage, the less likely it will feel real. This is because the "world stage" is actually pretty small because alliances are formed and broken about as often as someone changes their underwear and it would be far too easy for two nations to gang up on the third by forming an alliance. That means we need something to compel the space race that doesn't lend well to alliances on your planet. Wars tend to lead to alliances easily because the resources for and benefits of militaries are right here, right now. So... let's think of something that doesn't require war (although it might lead to it, and that's half the (\cough\) fun). What we want is something that won't drive nations to alliances, which suggests a benefit to the race that's so overwhelming that an alliance would be deemed a weakness after the race is won. There's something valuable in them thar moons! It's 1960ish, but unlike here on Earth, your world doesn't yet have nuclear capability. You see, your world has a limited supply of useful uranium. It's been discovered, tests are being run, espionage shows that your three players are pretty much neck-and-neck in the race for nuclear power. And then some enterprising scientist in a small country publishes in an international science journal that he knows where all the uranium is! It's in the moons! Said ~~idiot~~ scientist postulates that there was once one moon, but it was hit by a meteor that caused it to break apart (slowly...), causing some of the moon's material to fall to the planet — which is where the uranium came from. If he's like a math professor I know (one of the kindest men you'll ever meet in your life!) he's a bit involved with his work, and he didn't think any more about what that article would do to international politics than he thought about where he parked his car that morning. The race is on! Your three nations now have a reason to invoke a space race — and it can involve all of the tension of a "traditional" (if that word makes sense) cold war without having weapons of mass destruction at-hand. Whomever gets to enough uranium to develop a nuclear program (and nuclear weapons!) first wins the race. Best of all, because technology (unlike ICBMs) is easily stolen via espionage, it's rational to believe the three nations can keep pace with one another without resorting to alliances. Oh, alliances may exist, but they're poker chips, trading cards if you will, pieces to be moved around the chessboard. So long as the technology and manufacturing abilities of the three nations remain reasonably equal, you can rationalize no alliances that would tilt the balance of power away from the number three, so long as we have one more thing.... Why more than one moon? I thought about the efficacy of having just one moon, but from the perspective of building your societies, a single moon would too easily lead to the belief that whomever lands a "peacekeeping" force on that one moon first wins the race. I felt that for the development of your civilizations, it was too militaristic and would cause the associated economies and industries needed to facilitate the space race to be too driven by the [industrial-military complex](https://en.wikipedia.org/wiki/Military%E2%80%93industrial_complex). That would lead too quickly (IMO) to either creating a very real cold war or, worse, a fully-fledged war too easily. For the race to have time to complete, you need a balance of power on your planet that isn't too militaristic in nature. So I'm advocating a principally economic solution. The race isn't about weapons (yet), notably because convincing the public of that kind of expense just for weapons your opponents don't have (without the necessary war or threat of war to drive it) would be a pretty hard sell. On the other hand, the burgeoning nuclear power industry here on Earth promoted energy [too cheap to meter](https://origins.osu.edu/article/unkept-promise-nuclear-power?language_content_entity=en) along with promises of everything from cheap desalination (ibid.) to [nuclear cars](https://en.wikipedia.org/wiki/Ford_Nucleon). In other words, the economic benefits would be (and, historically on Earth, were) accepted by the tax-paying public. Worldbuilding Summary 1. Rather than a military cold war, I'm promoting an economic cold war. 2. Use an industry that, in the 1950-1960 time frame on Earth, promoted something remarkable and misunderstood, but could be limited by a terrestrial resource. 3. Place that limited resource somewhere in space that's attainable using 1960s-level technology. That's pretty much gotta be a moon. 4. Use more than one location in space to promote a race that can be "won" without resorting immediately to military force — but not so many that military force can't become an issue later in the race. 5. The "winner" of the race is the nation that becomes the preeminent economic superpower. My use of nuclear energy and uranium is story building. You could use something else such as aluminum to bolster the airline industry or radium for medical. Unfortunately, we have a lot of history with nuclear power, so it's low-hanging fruit. (And it gives you the option of becoming the preeminent military superpower.) ]
[Question] [ I'm working on a little project called Scrapbook Street where everything is made of fabric and or craft supplies, but while working on the world of the project, I've started to wonder how the world works. Some of my biggest questions are about the flora and fauna of the world; mainly the dominant lifeform of the project, the PatchPals. The PatchPals are made from fabric, and their insides are all stuffing. Their eyes are buttons, which can blink and such. How would I go about explaining the scientific reasons for how these creatures are sentient? Another question would be on the crops, which are made of fabrics, just like the PatchPals, but grow with sun and water just like Earth plants. Would there be a scientific explanation for their fabric textures? [Answer] No need for science in a story like this! And you are in good company. > > “Who are you?” asked the Scarecrow when he had stretched himself and > yawned. “And where are you going?” > > > “My name is Dorothy,” said the girl, “and I am going to the Emerald > City, to ask the Great Oz to send me back to Kansas.” > > > “Where is the Emerald City?” he inquired. “And who is Oz?” > > > “Why, don’t you know?” she returned, in surprise. > > > “No, indeed. I don’t know anything. You see, I am stuffed, so I have > no brains at all,” he answered sadly. > > > “Oh,” said Dorothy, “I’m awfully sorry for you.” > > > “Do you think,” he asked, “if I go to the Emerald City with you, that > Oz would give me some brains?” > > > “I cannot tell,” she returned, “but you may come with me, if you like. > If Oz will not give you any brains you will be no worse off than you > are now.” > > > “That is true,” said the Scarecrow. “You see,” he continued > confidentially, “I don’t mind my legs and arms and body being stuffed, > because I cannot get hurt. If anyone treads on my toes or sticks a pin > into me, it doesn’t matter, for I can’t feel it. But I do not want > people to call me a fool, and if my head stays stuffed with straw > instead of with brains, as yours is, how am I ever to know anything?” > > > [The Wonderful Wizard of Oz, Frank Baum](https://www.gutenberg.org/files/55/55-h/55-h.htm#chap03) Fantastic things belong in fantasy. How do the Candy People ruled by Princess Bubblegum work, scientifically, being made of candy? How do zombies get energy to move without breathing? How does Goku lift an object thousands of times his own weight and not drive his own body into the earth like a tent peg? How do Rainbow Dash and Minty pick things up, given that they have digitless cylinders at the ends of their forelegs? It is ok. It is fantastic! Your world sounds awesome and very cute. Except when I think of Coraline and the world where people have button eyes. Then I get the willies. Make up rules that are consistent for your world except when you break them in the service of storytelling. Science can stick to greenhouse gas, and leave your crafty folk alone. [Answer] ## Fungal structures While I'm firmly on the "don't explain fantasy worlds unless forced" bandwagon, "give the questioner what he/she asks for" is important too. Fabric is ultimately a bunch of ordered fibres. In this case, these ordered fibres can grow and change and form more complex structures. Maybe the fabric is a complicated fungus growing medium? In response to water and sun, it's able to sprout more complicated structures. This isn't a great explanation but it may be better than nothing. It also explains why your house or at least your sewing room is probably full of loose threads despite diligent cleaning; the fungi are determined to replicate! [Answer] The "fabric" is a phylum of plant or fungus. Let's call it Fabricus. [Moss](https://en.wikipedia.org/wiki/Moss) or [Lichen](https://en.wikipedia.org/wiki/Lichen) are the closest things I can think of; you can extrapolate from those a type of organism that produces colonies that look distinctly fabric-like. Given this, PatchPals are a symbiotic relationship between species in phylum Fabricus and intelligent animals. The "fabric" is the plant/fungus, and the "stuffing" is the inner animal. Intelligent animals can have mushy consistencies sufficient to be stuffing, such as octopuses or jellyfish. This has the additional benefit of explaining how "plants" work in this world. Plants are just other species in phylum Fabricus that grow on their own and build rigid structures, rather than growing on the surface of an animal host. Some types "plants" could actually be edible by members of the species (if that is desired). Having this happen underwater makes this all more plausible, as that makes it much easier to have gelatinous animals. Note that you can set it underwater without ever mentioning that it is underwater, as if water is everywhere, it is just the assumed surroundings of everyone in it (most people don't go walking around commenting on the air surrounding them on a regular basis). Sure, movement works different underwater, fire is a lot harder, and you don't have weather, but those are all changes you probably need to make to have plausible land-based fabric creatures (I assert that land-based fabric creatures wouldn't do very well with fire, rain, or heavy winds). [Answer] I think the two current answers are very good but I thought I'd give an answer that explores why you might choose one or the other. Which kind of comes down to some differences between fantasy and science-fiction, and the actual science of how living things, fabric and craft supplies are. I think one way of understanding fantasy vs science-fiction is considering "magic" vs "mechanisms", where "magic" is essentially when the effect comes first, never mind how it came to be, and "mechanisms" are the situation where certain causes have certain effects and the cause always comes first. Think "magic love potion" vs "aspirin". A "magic love potion" makes you fall in love - that it's essential nature. The cause is very simple (you drink the potion), and the effect is nothing more and less than "a person is now in love with another". On the other hand, "aspirin" is a certain molecule - that's its essential nature, the collection of atoms it's made of. It so happens that taking aspirin relieves headaches, but that effect isn't fundamental to what aspirin is - in fact the aspirin molecule can have other effects, such as thinning blood, and the effects can change if the circumstances change, like if the molecule got degraded by heat or cold or if the body has a structure that reacts to that molecule differently. So you can see fantasy as an aesthetic where you focus on effects first, and either want to give the explicit impression things don't have an internal structure that causes these effects, or you just don't want the reader to care about that structure at all. Whereas science-fiction is an aesthetic where things might have effects but you want to give the impression that all those effects have underlying mechanisms, like science tells us effects have underlying mechanisms in our world. (I like how this matches up quite well with David Eddings' definition of the difference, even though he was obviously biased - his definition, paraphrased, was "science fiction presents you with a watch and goes into deep detail into how it works; fantasy tells you what time it is and gets on with things") It's not that magic systems cannot have internal structure per se, or that science-fiction cannot present effects whose mechanisms are so handwaved that they effectively don't exist. I think that's where the "aesthetics" part comes in. Compare how Star Wars (OG and prequels at least, I'm not up to date on everything) treats the Force vs faster-than-light travel. The Force comes across as a mystical, magical thing - the world is science-fictiony but that specific concept is presented as magical within that world. On the other hand faster-than-light travel comes across in the usual science-fiction way. It's not because of the detail the story gives in terms of mechanisms - the first movies and more so the prequels spend a lot of time talking about the Force, how it works, even injecting a "science mechanism" to underlie it in the form of midichlorians in the prequels, while faster-than-light travel is just there, it's not even explained or handwaved, it's as much an effect without a mechanism as anything can be. The difference is in how we're supposed to think of those things - the Force is fundamentally about humans doing things humans want and the thing "just happening". There are rules, but they're all around how humans want things and whether they should want them. The midichlorians are presented as a mechanism but not treated as such - when using the Force goes wrong it's not because that person's midichlorian count was low that day, it's because Luke felt conflicted and unsure about his goals or because desiring immortality is inherently ill-considered. On the other hand the faster-than-light drive, while it's never explained, it's shown to us as if it's an engine, and so we assume without having to be told that it must have mechanisms like engines do in our world. When the faster-than-light drive fails in the Millennium Falcon it's not because of deep issues about faster-than-light travel as a concept or because Han Solo didn't interact with the concept correctly, it's because there's a problem with the engine and Chewbacca needs to go back there and mess around with wires - fix the mechanism. So I think the question for you should be, what vibes do you want to have? It sounds like you want more of a science-fiction feel - you want people to think that your animals made of fabric and stuffing move and breathe like real animals because of underlying mechanisms that make it happen, like real animals, and not "they're made of fabric and they're alive, period" like in Toy Story or Coraline. The problem in terms of the actual science is that... there is no "scientific" explanation that makes your world work as presented. It's a bit like nailing jello to the wall - can you do it in this world? No, because of how jello and nails work. Can you imagine a science-fiction world where it would work? Well... you can certainly imagine a world where something called "jello" gets something called "nailed" to something called "a wall", but for it to work on a pure logic level you have to twist the meanings far enough to break. Like, you can make a science-fiction world where jello has the consistency of plywood, and you can use the word "jello" all you like but your reader will see that it's actually plywood and react accordingly. The scientific reason your idea doesn't work is in the biology and physics of how life and fabrics and stuffing work. Life involves things doing things - moving, maintaining their internal state, perceiving the world, acting to achieve goals accordingly. These things are what in physics is known as "work", and in order for "work" to happen you need specific systems that capture and transform energy from outside the system to decrease the entropy inside the system by increasing it outside - meaning life also involves taking in energy (in the form of sunlight for plants, food for animals), having complex mechanisms to convert that energy into the various work the organism does, and expelling waste and heat. This is all stuff that requires extremely complicated internal mechanisms with many different moving parts, and the more flexible and interesting the things the living thing does the more complicated and varied the insides need to be. On the other hand "fabric" and "stuffing" are simple things without a very complex structure, and it's hard to change that without changing their vibes. For example, "stuffing" is a thing that's shapeless and soft to the touch and reacts the same way whatever direction you poke it in... that inherently requires a certain lack of complex structure. Nobody ever used a car engine as a pillow, and while you can use an animal or person as a pillow it's kind of a delicate thing to do without damaging them or being uncomfortable because your head is on one of the hard bits. Similarly, "fabric" has more internal structure than stuffing but it's a very simple structure that makes a fairly simple, uniform material. That makes it very good for having the properties we want fabric to have, but very bad for making something act alive. So with this I see three options for you: * Go straight fantasy - your animals are made of fabric and stuffing, and they're alive, and that's it. It's a fantasy world or a magical element of an otherwise non-fantasy world, don't worry about it. * Go hard science-fiction - you try and square the circle of how "fabric" and "stuffing" can have enough internal structure and complexity to allow things made of them to act alive. I think squaring this circle requires corrupting your "fabric" and "stuffing" until they have only the name and maybe only the most superficial appearance but they won't behave like our fabric and stuffing. But that can work fine if you only want some of the properties of "fabric" and "stuffing". I think the important thing there is to understand - your animals will be basically animals (or robots, depending on how wet you make them), and the buttons/fabric/stuffing will exist in a very limited form, like "they have hard, glassy eyes like buttons and their skin is soft and made of woven fibers like fabric" or "the process by which they came to be involved fabric but the end result transformed that fabric to the point it's basically living tissue/microprocessors" or whatever. * Go soft science-fiction - like the FTL drive in Star Wars you give a vague impression that there's a mechanism there but handwave it hard. I think an important thing to understand here is that - there is no science here. You don't want actual scientific explanations, because actual science makes what you want impossible, you want something that looks like a scientific explanation. Something where the reader might think "I can buy that this is a world with scientists, and that this is something those scientists might say even though the scientists in my world definitely wouldn't, because that world plays by different rules". That's where AncientGiantPottedPlant's "it's fungi" idea can work; it associates something we know is alive with something that has some of the properties of fabric and stuffing. May I also suggest "nanofilaments", "nanocarbon tubes", anything with "nano", which suggests a complex mechanism that's just at a scale smaller than the apparent simplicity of "fabric" and "stuffing". A hundred years ago you could have played with "magnetism", a kind of mysterious force that can apply to anything and do everything. Heck, what about "electricity"? That's quite old-school in terms of "science-fiction handwave for life", it goes back to Frankenstein, but the fact fabric is inherently associated with static electricity makes it a really fun association IMO. Might work better for a humorous/retro soft science-fiction vibe in our 21st century. ]
[Question] [ I am working on a speculative evolution project at the moment that has a low atmospheric scale. As a result, the ground is almost always covered in fog or cloud-like fog that is universal across numerous humid biomes. A small minority of the year will see a reduction to this fog. Visibility can vary from a light mist to a dense fog, with somewhere in between being the average. Fog reduces visibility, as anybody who went outside while it was foggy would know. An animal with poor vision could not hunt or forage in those conditions without specific adaptations for it. So, I am inquiring about what types of eye adaptations would help an animal in vision-impaired conditions such as this. The specialization of any recommended adaptations shouldn't be a concern as my basic reference are slug eyes. Some quick things I would like to mention: * I do not want the animals to hibernate for the entire year until it isn't cloudy. I feel it would be inevitable for an ecological niche of animals that adapt to living in the fog. After all, nocturnal animals exist. * I do not want the animals to be blind. Some blind animals are fine but I would like to see more creative solutions. These animals are unlikely to devolve their eyes, which are their best source of sensory stimuli, in favor of evolving borderline non-existent sensory systems. I appreciate scientific accuracy, but it is not a chain here. So, the question at hand is "What type of eyes are best suited towards constant ground-level fog and cloud cover?" [Answer] Long wavelengths scatter least. I was once approaching a stoplight in dense fog. It was red. Then it disappeared. When I got closer I could see it had turned green. The green light was scattered by the fog but the red light could get through. That is also why sunsets are red. The longest wavelengths make it through the intervening air while scattering least. Shorter wavelengths are lost to scatter. Unscattered light carries with it information about things it has reflected off. Eyes adapted to see in red and infrared would work the best. As far as eyes go, maybe the best vision would not be an eye. The [pit organs](https://www.nature.com/articles/news.2010.122) that some snakes use to see heat (far infrared radiation) are not eyes and have no analog in other vertebrates. A radiation detecting organ like the pit vipers pit could be superior to eyes in an environment where shorter wavelength radiation is scattered. Example: here smoke stands in for fog. Visible light is scattered but the infrared comes right through and is seen by the thermal camera. [H4 Thermal Camera Line \| Smoke Test \| Part 2](https://www.youtube.com/watch?v=9d39I7JC_pA) [![thermal camera thru fog](https://i.stack.imgur.com/zCyox.jpg)](https://i.stack.imgur.com/zCyox.jpg) [Answer] Under such conditions it might be better for animals to have a preference for using echo location (bats) or enhanced hearing (some owls). More useful information can be obtained via sound from one's environment when vision is of limited value. The trouble with a foggy environment is daylight can be bright but vision is obscured by an opaque atmosphere. I initially thought animals might have eyes similar to what nocturnal animals have to compensate for low light levels but a foggy atmosphere may not be dim, just opaque. As the other answer states, eyes developed to process longer wavelength light (red and infrared) would be better. A higher developed sense of smell would also assist animals. [Answer] Consider adding polarization to the long wavelength vision mentioned above. [Polarization](http://www.cs.cmu.edu/%7EILIM/publications/PDFs/SNN-CVPR01.pdf) can be used to reduce the effects of scattering. You combine images made with different polarization with some tricky processing to get much better contrast. Animal brains already do a lot of processing to combine the images from two eyes to a stereo view. Give the critters eyes that are polarized differently, and a somewhat [larger visual cortex](https://en.wikipedia.org/wiki/Visual_cortex) to do the processing. Besides the improved contrast, your critters will gain the ability to detect the sun even through heavy fog using the [sunstone effect.](https://en.wikipedia.org/wiki/Sunstone_(medieval)) [Answer] Our own environment is foggy. Atmospheric scattering of EM radiation known as Rayleigh Scattering begins with blue and becomes more pronounced as frequency rises. This is why the visible spectrum is where it is. Any lower would lack resolution at range, any higher would lack range. The world you describe will be without meaningful distance vision. In the absence of distance vision, visual apparatus will be more strongly driven by factors other than focus. Omnidirectional motion sense, for example, is better served by faceted insect eyes. They can't see worth a damn past a metre but sneaking up on them requires very slow movement till the hunter is in range, then very fast movement like a frog's tongue. Or set traps like spiderweb (sometimes a snare, sometimes a telltale). But my answer is that non focal motion sensing eyes are best adapted to the conditions you describe. Ooh, I forgot about polarisation as mentioned by another answer. That will partly solve the scattering problem. And it's entirely evolvable — slitted pupils, for starters. While that won't give you distance vision as we know it, it would certainly be a survival edge. ]
[Question] [ It is a scifi space opera setting skewing more towards realistic consequences of its breaks from the reality - quite similar to The Expanse. Considering the situation outlined below, would it be feasible for piracy to exist in any capacity in this setting (of any kind, from the classic space pirates being their own faction, to something closer to real-life Somali piracy)? ## The setting has the following conditions of space flight: * Spaceships fly obeying physical laws - and distances, - the only things being handwaved away are the FTL, propulsion efficiency, and heat generation. * Only relatively large spaceships can go FTL (60m in length and larger). There are no man-manned fighters, but there are drone ships trying to fill a similar role (Expected to be expendable). * Usual weaponry target range is from several thousand kilometers up to one light second of distance. * FTL is not instantaneous and is of "shortcut through a wormhole" variety, travel time takes from a few days to a week of transit, and you arrive in a random spot within a sphere of up to 1 au in diameter from your targeted destination location in the system (More expensive ships have much better accuracy, but the precision limits are still at tens of thousands of kilometers in ideal conditions). To go from one star system to the other, the spaceship must chain several jumps, each of which should end not too far or too close to a star or other similarly massive body (no more than 60 au and no less than 5 au for a star of a solar mass, the local large scale spacetime curvature is the deciding factor). Before proceeding with the jump, the spaceship must match the predicted orbital velocity and vector of the destination's star as close as possible, and there should be no planetary objects in the vicinity, on in the line between here and the destination. Most ships travel out of the ecliptic for a week before making the jump. * Considering the massive scales involved, there are no defined routes or lanes of travel, even if ships tend to use relatively small portions of galaxy to travel between two known destinations. * STL speeds are defined by the ship's acceleration capabilities; most ships don't risk accelerating faster than 2G under normal circumstances. * typical length of the journey can clock up to a couple of months of travel, and in extreme cases up to a year. * There are no FTL communications except dedicated messenger ships, and no FTL sensors. * There are virtually no privately-owned spaceships sans for few rich assholes. Every spaceship is rented along with the crew from either the government or licensed companies. Furthermore, spaceship maintenance is quite expensive. * All ships and all space stations can't reach true self-sufficiency and need to renew their resources. * Since any ship in the setting can accelerate for months at a time fast enough for that to be used as means to simulate gravity onboard, this means that every ship is a potential relativistic kill missile capable of wiping out continents. Any suspicious activity in an inhabited system immediately gets the attention of police forces and defense systems, with reactions up to immediate termination of the suspiciously acting vessel. * The only kind of stealth in the setting is "go on a passive ballistic trajectory with a shutdown reactor and pray your current position won't be extrapolated out of your last known positions and velocity or be spotted against CMBR by chance anyway" * Space is explored very sparingly, out of a few billion star systems technically within reach, only a fraction of a percent was ever even visited by a passing ship or a mapping probe. Planets with biospheres are relatively rare, not all of them have friendly biochemistries. * Most spaceships are not designed for an atmospheric flight, shuttles are used to get to and from the surface. Shuttles are vulnerable during reentry. * There is a unified UNN-like government handling interactions between civilizations and police actions, but a large travel time coupled with a lack of instantaneous communication means that every star system far enough from the administrative centers is de-facto a self-governed independent nation. * Interactions between these various civilizations are more or less peaceful, there's no open hostility or competition for the resources. [Answer] Let’s look at this history and present state of piracy for examples. Piracy isn’t done in the deep oceans. It happens along coastlines, usually within sight of shore. This isn’t just modern piracy. Daniel Defoe documents piracy working this way in ‘Robinson Crusoe’, published in 1719. Even further back in antiquity, Robber-Barons were men in the actual employment of the local ruler. They were sent to intercept passing ships along the rivers, or waylay travelers along the road. So, scale this to space : asteroid stations like Ceres, or Bennu pass as close as one-day’s travel to Earth for a “piracy season” once per year. This is likely true of other asteroid belts around other planets that people want to go to. Also true of the Kordelewski clouds operating at +60 and -60 degrees offset from the orbits of each major moon, or planet. Putting that together, I think you’d see your pirates are “solid citizens“ of a remote place that sometimes passes close to a world that people want to trade and do business with. When a traveler passes by close enough to reach, these “solid citizens” launch off in a borrowed or rented ship to “inspect and seize contraband” as well as assure that “duties and taxes” are fully paid. [Answer] A strong yes. I'll get into some of the reasons why and hopefully that's enough to get the ball rolling. Going off your list: A lot is going to hinge on the mechanics of this FTL system. In classic Battletech for instance, a jump is detectable in the arriving system as a huge burst of IR radiation (detectable at short ranges) and a large EM pulse that can be detected from further away, delayed by the speed of light. In that universe jumping takes a lot of energy and a ship has to spend days recharging before it can jump again. That would be a dead giveaway to a group of pirates that there’s a potential score stuck in realspace they could possibly intercept. *Considering the massive scales involved, there are no defined routes or lanes of travel...* This complicates things from the pirates’ perspective, although if the ships do have to stay near relatively massive bodies to anchor their jumps then it’s all going to come down to picking the right location to hideout. *typical length of the journey can clock up to a couple of months of travel, and in extreme cases up to a year.* This implies non-perishable / preserved goods, which is a point in favor of piracy *There are virtually no privately-owned spaceships sans for few rich assholes.* This is a pro and a con. On the pro side, that’s fewer craft to hear distress signals, observe signs of battle, interfere or summon aide. On the con side, said government and corporations are going to keep a watchful eye on their craft as they represent a huge investment and high risk. It’s going to be harder for would-be pirates to get their hands on such a spacecraft, especially an FTL capable one. Granted, you don’t need an FTL vessel to catch another FTL vessel, all you really need is to get a boarding party aboard. But you do need to sell the cargo somewhere assuming you successfully capture it. But capturing the ship is just the first step. Next you've got to get its goods to market without being caught, and that implies a whole black market for fencing said goods. Step 2 is get the ship somewhere you can offload the goods, ideally sell them to a 3rd party. But the real prize in this case is the vessel itself if its in good condition, or its stripped parts if its too badly broken down. *Since any ship in the setting can accelerate for months at a time* This is one spot I’ll raise a reality check flag. The only way to sustain that kind of acceleration would be with a highly efficient, low impulse technology like an ion engine that uses very little physical fuel. Once you go to high impulse fuels, the math simply does not support this mode of travel because more and more of your vessel would have to be dedicated to storing fuel. Then you need bigger engines to push the increased mass, and then more fuel for the hungrier engines. Pretty soon you no longer have a cargo ship but a fuel tanker. Faster ships that build up a lot of speed by accelerating like that only makes sense for time-sensitive cargo. But that is also going to increase the cost of transport considerably. Freight is a competitive business, so a ship that can dedicate more space to cargo room and burn less fuel overall (also avoids having to refuel) is going to save a lot of money. The long travel times and limited replenishment also favors the smallest crew practical, and in turn less storage for food, water, oxygen. This is also a plus for piracy since a smaller crew is easier to overpower *The only kind of stealth in the setting is "go on a passive ballistic trajectory with a shutdown reactor* Getting a bit into the weeds of tactical details here. If you were already being tracked by radar / IR / optical telescope at short-medium range its not going to matter much whether you suddenly shut down. You’ll still be visible. Your engines will even still be warm. One way to try to shake a pursuer detecting you at medium-long range might be to enter a region of space that sufficiently masks your signature change course or stop and then shut down. But that would be a drastic action that costs the fuel needed to decelerate / enter an orbit and abort your current course. The better option would be to just burn the fuel and see if you can outrun them. The lost fuel is cheaper than having to alter course / abort the transit. *Interactions between these various civilizations are more or less peaceful, there's no open hostility or competition for the resources.* Here’s another spot I’ll raise the reality check flag. Colonization efforts will have met with wildly different levels of success, with some colonies thriving while others struggle and others fail. Interstellar commerce between these colonies means there are goods are in demand all over the place. Colonies might have a good deal if they can export raw materials like noble metals or radioactives that are hard to come by on other planets. In exchange they’d want to import fresh bodies, manufactured goods and supplies needed for a colony to succeed. Terraforming equipment, fusion reactors, mining equipment, vehicles, colony domes, life support stuff, communications gear, spare parts, tools, all of these would be hard to come by on the frontier. And where there’s scarcity, there is opportunity. That’s where both legit traders and pirates get interested. One obvious place to start would be the scarcest good of all: the ships themselves. The list here suggests there would be a strong market for shady secondhand ship parts, and salvage / chop-shop operations that make the authorities curious. Another ripe opportunity is that the government / colonial powers aren’t at war. This suggests wars by proxy instead – pirates that are very well armed and equipped for instance with military grade equipment quite obviously supplied by someone so they can go raiding on a sponsor’s behalf without incriminating them. Then there’s the saddest category: unemployed sailors are by definition pirates. Let’s say one planet is great at making cars, but some shipping mogul brought in a mega-cargo full of cars, flooded the market to drive down costs and drove most of them out of business – then bought them out at firesale prices. Totally believable scenario, which gives the natives a strong and legitimate self defense interest to blow up said shipping vessel and its cargo. You get the idea. Trade wars are nasty. So in conclusion, there would be pirates in developed inner core / worlds rich space trying to get a market advantage, and pirates in the frontier just trying to survive. Either way you’ve got to catch one of these ships somewhere along its transit, --intact--. That means boarding it with assault shuttles and maybe escorting / raiding it with smaller craft like fighters to disable its defenses, jam its transmissions. Doing it with the least expenditure of fuel, weapons, loss of life and damage as possible is how to do this profitably. I imagine some captains scare easier than others, since they know they’ve got valuable crew and if the pirates get aboard they’re probably dead. Gives a strong incentive to run. [Answer] Piracy as extortion No need to match speed, your not after the cargo or the ship, just the wealth. If your pirate obviously outguns the target or has built a deadly reputation, they order the ship to transfer crypto currency (or whatever your secure anonymous cash method is) to their account to allow for safe passage. The victim complies or is destroyed. They stay in kill range long enough for confirmation of transfer. [Answer] There is great difficulty in matching speeds between two spaceships when one or both of them is relativistic and their velocities are not originally aligned. If ships do not have super-strong shields, which you didn't mention, it also doesn't take a lot for either to simply destroy the other once at close range. Therefore, space piracy requires cooperation on the part of the victim. The pirate and victim will need to perform a delicate dance of mutually-assured destruction and reputation management. The logistical requirements for space piracy are: * The pirate must get in a position where he can certainly kill his victim if he wishes. He may achieve this by loitering around a typical FTL end zone. * The pirate must be able to communicate with his victim and credibly reveal his capability and willingness to kill the victim. This credibility is improved if the pirate has a documented history of killing non-cooperative victims. * The victim must voluntarily change course to allow the pirate to board. This chance is improved if the pirate has a documented history of releasing cooperative victims. * When the pirate and victim get close, the victim likely has the capability to just kill the pirate. If the victim has a weapon that can kill at a distance of 1 light second, it could kill almost instantly at a distance of 100m. For the piracy to be successful, the victim must refrain from doing this. The only reason the victim would refrain is if the pirate has a credible threat of mutually-assured destruction (MAD). * Under this continued MAD threat, the pirate must board the victim's ship and acquire items, persons, or information of value. Excessive resistance at this stage by the victim needs to trigger the pirates' MAD threat, and the victim needs to be convinced of this. * The pirate must release the victim, with his ship, at the end, to maintain his reputation so future piracy attempts will succeed. * The pirate must either escape law enforcement by jumping to a different system, or have local law enforcement in his pocket. He may be a privateer with tacit government support. * The whole process, including the cost of fuel and the risk of death, needs to be profitable for the pirate. It is conceivable that the victim could turn the whole process on its head. Since both ships are assumed fragile, and both parties probably have weapons capable of killing a ship at close range, MAD goes both ways. The pirate is relying on his reputation for MAD if the victim does not cooperate or retaliates, but the victim could build up the same reputation for MAD if the pirate tries to carry through with his plot. So the pirate needs to know the identity of his victims, and if the prospective victim comes from an organization with a reputation of death before dishonor, the pirate needs to just kill them before the victim gets close enough to kill them back. Reputation must be managed at the level of firms of pirates or firms of merchant ships, not individuals; after all, it's hard to build a consistent record for MAD when the first time you use it, you die. The pirate or merchant firm can demand certain behavior from its employees, and build hardware failsafes into all its ships, with guarantees of execution if the employee fails to uphold the code of behavior, and payouts to the employee's family if the employee dies upholding it. [Answer] ## Yes to local system piracy. Ships could ambush other ships among asteroids or routes from planets to planets. Gravity dictates the cheapest route, so it would be easy to travel along a route. After they get their loot they could simply go to a place with lots of ships, and then no one could track them. Pirate havens. This would require some degree of tolerance among systems, either from nationalistic pride (e.g. the ships target foreign ships) or from a megacorp sponsoring the pirates and discouraging defense forces from targeting them. ## Yes to colonial piracy. A few people with heavy weapons could easily go to a new system with a few ships and steal all their stuff, away from dedicated system defenses. Fixed defenses are inherently inferior to mobile ship defenses because you can just toss rocks at them till they break. ## No to interstellar piracy. With no fixed routes pirates would need to search for decades to find decent prey. This wouldn't be profitable so they wouldn't. If you want interstellar piracy you need to change the ftl system so that ships need to travel along fixed routes for fuel efficiency or safety reasons. [Answer] # For a given value of piracy Maritime piracy is defined as an act of robbery or criminal violence by ship against another ship or a coastal area. As others have said, matching speed with another ship in space might be extremely and even prohibitively complex. From playing KSP I can tell you that a miscalculation of even a fraction of cm/s in a burn meant to intercept a faraway body can mean you won't ever get close to it, so a ship can defend itself against piracy by doing small accelerations in random directions along its course. Planets don't have this luxury, though. Pirates could insert themselves onto low orbit and demand credits in order to not jettison debris. If their demands are not met, they let go a lot of dust which is sure to wreck some satellites and orbital stations. And when the orbital guard arrives, the pirates can just FTL out of the place. They can run from military spaceships the same way that other spaceships run from them. [Answer] In a realistic setting bulk cargo is out of the picture. Shipping costs are way too prohibitive. If a colony cannot manufacture anything that is heavy they are not going to get them. This limits types of shipment. I will assume most ships will be carrying high value, highly processed goods such as micro controllers; or people. Pirates should account for these to select locations for ambush. They should stay close to a planet, likely on a moon or a captured asteroid over a planet that is in process of colonization or expansion. Once the target vessel is in range and the position of moon/asteroid is in between the planet the target, they will start the burn towards the ship. Hopefully for the pirates, the target ship will not have too much extra fuel to do a full evasion. Once they close the range, they will either extort credits, or they will try to board and take the goods. First will be much more preferable. Some pirates will destroy the vessel without boarding. They may also request some cargo to be thrown overboard for pirates to pick. However, there is a huge issue in this setup. Once a pirate ship is identified, it will be very difficult for them to refuel, event if it takes a while to get messages to nearby star systems. For this setup to work, you need pirate friendly systems that the pirates can refuel and trade. Pirates should either be locals or some informed people that know about expansion events. Locals will have difficulty in returning back to planet it is difficult to hide your intentions in space. Only way to get this work is again pirate systems. You pound on the target, get everything, jump to the pirate system. Grab a legitimate transport from there back to your world. Which could take many many months. Interplanetary attacks that doesn't end in genocide is almost impossible. Thus pirate systems cannot be effectively dealt with by legitimate authorities. UN equivalent will only be able to do surgical strikes to deal with particularly dangerous pirates. But most of them will be spared. To summarize, piracy would be easy to pull off in your system. But it will be more difficult to plan, execute and get around. Most likely you will never get caught but chances are, you will not be very rich either. Thus expect a few pirates, but they will basically be untouchable. [Answer] The reason piracy exists currently, and in the past, is because it's cheap. Pirates with "nothing to lose" and cheap equipment going up against targets with "everything to lose". Spaceship piracy, as an independent effort, puts this premise on it head. I don't know how much spaceships cost in your universe, but I have to assume "a lot". "A lot" to the point that if you weren't pouring millions of Interstellar Ducats in to the spaceship, you'd instead be spending your time on the beach of some exotic planet with dual suns sipping cool refreshment from a drink container with an umbrella in it. Since spaceships are expensive, they're expensive to maintain and, more importantly, expensive to repair. "Should I spend a million ducats on repairing the space drive, or retire?" starts become viable questions. As an independent contractor (as pirates tend to be), the participants start to really struggle with "what am I doing out here in the first place". If they have the money to maintain a spaceship, why aren't they just getting out of the business (especially one as dangerous as piracy) and spending the money on that instead. One successful haul, using a hijacking, or fraud, or a rigged poker game to get a ship that can be sold on the black market, is enough to set most anyone up for life. State sponsored piracy is a different problem. These folks are getting middle class salaries and bonuses. They're doing it for King and Country. But, that's effectively a covert military operation. When folks start shooting at each other, piracy gets very expensive. Worse, commerce gets very expensive. When commerce gets expensive, the Navy shows up, because trade in general wants commerce to be cheap. And, unlike the pirates or the traders, the Navy has deep pockets. A couple of solid hits to a pirate ship completely puts them out of business, so the naval threat is very real. A couple of hits to a commerce ship puts them out of business to the point that not only does this ship no longer offer trade, nobody else does either. They can't risk it. Because nobody wants to spend millions of Ducats to move cargo if the price of moving cargo is the loss of spaceships (much less, their crew). There's still lot of room for extortion at the ports, corrupt unions, bribed inspection officials, etc. Low enough costs to the traders to where they're in the background din of running the operation. If the operator is dumping 1 million Ducats in to ship maintenance each year, 100,000-200,000 more in "insurance" isn't enough to stop the enterprise, nor enough, necessarily, to drag in the authorities. But galavanting among the stars, punching lasers in to each other, doing millions in damage for a cargo of out of season fur coats? No. Not a viable business plan for any participant. Remember, the environment will adjust to the piracy threat (naval escorts, convoys, closure of trade routes completely, nation state force against the pirates, etc.). [Answer] There is some inconsistency in limitations, but not a big deal, can be explained fixed in all kinds of ways. Situation as described is - piracy neutral. There are some difficulties to overcome, there are some advantages or helpfull things. Incentive isn't strong, so excluding colonies (like space habitats) and planets(in the first place) traveling around looks as relatively safe activity. And what may or may not happen, mostly depends on activity of those who are stationary in the system. Depends on the means which are deployed there beforehand. Planets are obivious targets, after them space habitats - but on the other hand they can be well protected with non FTL means and be quite safe in their systems. It has to be done, meaning it(safety) isn't some inherited property, but a result of technological activity and setting proper means beforhand. So for uninhabited star systems, which are not under permanent control those can be converted in traps(in similar ways as inhabited ones are reinforced), it takes time and effort, and one needs somehow to predict (a mole which suggest brilliant route, treasure map, rumors, whatever) that there will be some traffic, as single ship probably won't cover the expenses of setting up such trap which worth a fleet of ships(not necessarly, but it depends on specific technologies and approaches, which I do not assume, but it not that hard to set a trap if they are present, but it requires time, years, and not that easy to hide such preparations) So is there piracy or not depends more on what people and organisations do. If they like build safe routes, they may do that, if someone wants to conduct an attack with a planning it also possible. But considering more than 90 perdent of star systems under no ones control then working on exploiting those systems seems to be a more profitable activity, and clashing there for reasons of to obtain control it may be more likely, as competition of establishing control over the system(if it so so attractive for some reason, as else there is 90 percent). And once control is established, it will be hard to evict those guys and they can set their own rules on passing by ships. So some taste of 400-1000 A.C. here, except of absence of obivious reasons for route preferences in most cases. So it looks more like establishing routes, keeping control over system, enforcing rules, and taking tax, eh misspeled, ransome for passing trough. So as providing service blackjack and ...s, food and repair, oil change and all that - so just typical capitalism activity. With attempts to replace an owner, which more or less does not affect guys who are passing by and be more behing a curtain deals and activity. Taking such tax may be counted as piracy activity, and if it is then piracy probably does exists there, or we can call it local gov tax for expenses to keep high security standarts in the local system That unknown origin of ships is a bit of a problem in the picture I envision, and people will definetly try to solve it, and it can be done in a number of ways, including negotiation like we will keep the system safe but you give us x number of ships, or else we try our luck capturing them - I mean just regular politics here, over 9000 of ways to make a deal, create opportunities. Capturing ships is not impossible even if one does not have ships to begin with, and only neccessarly condition is to be delivered to some celestial body in a system and have about 100t of cargo to secure the system in about 5 years, and then reroute as much ships as possible with moles, rents, whatever. Not talking about more direct approaches to steal those trough infiltrations and other means. So ships themselfs are the only interesting target here and to gain control over one it does not need piracy, it need highjaking or other similar means, until interested groups get the technology or what they want, if getting technology is possible, as one can set realistic hard limits there, but renting in such situation seems very unlikely, for multiple reasons and without hard limit tech will be cracked, there are multiple ways to do so and then even if ships stay valuable one can gain more from other star systems, and ships themselfs are just expensive(or not) tools to make things happen. ## Conclusion You safely can place any type of piracy, so as you safely can eliminate any piracy or anything in between in a way you see fit, and make things to be in a way you like - there is full freedom in that aspect. Current set or constraints is quite a good vehicle which can be driven at any road, at any direction. * however limits on ship technology, those being non expendable units probably drives situation to order, and incentivise to suffocate the possibility at its roots. And 90+ percent space which is suitable for hiding and having own bases is not helping at all in this situation. Pirates cann't guarantee they get more ships than they loose, and it too "easy" to make the activity to be extreamly non profitable. Even a strategical genius may have hard time to break the situation, but not impossible, it depends on what people do and what they have but it will be rare exception and rather a way to establish oneself than an end goal to be a pirate for life, as this activity is gambling and can be made not sustainable in short to long run. So, depending on how valuable ships are it affects the situation - if they are expensive they are goal but at the same time reason to enforce strict security, if they are cheap enough ships are not attractive targets and better participate in some gold rush and make crimes closer/inside where the activity happens with regular means and without ships, I mean in a usual ways and existance of ships and space travel does not play deciding role. [Answer] Time travel piracy. It is easy to ambush a person if you know where and when they will be. This is how your pirates do it; they scout the victim then travel backwards in time to ambush them at the perfect opportunity. FTL means time travel. [Are there any ways to allow some form of FTL travel without allowing time travel?](https://worldbuilding.stackexchange.com/questions/46873/are-there-any-ways-to-allow-some-form-of-ftl-travel-without-allowing-time-travel) > > Thus, due to symmetry, the FTL drive functions as a time machine. You > can choose your spacettime axis, jump far enough to amplify the > difference between time axes of different observers, and travel into > your past using multiple jumps or travel into the past of another > traveler. > > > "But it is really hard!" one might protest. "Multiple jumps! Circuitous routes! We have FTL jiggery pokery!". Lazy or stupid pirates will not be able to figure it out. Able and intelligent pirates will. Then the lazy ones will hire some of those and give it a go. ]
[Question] [ Closed. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Add details and clarify the problem by [editing this post](/posts/201591/edit). Closed 2 years ago. [Improve this question](/posts/201591/edit) A continuation of [Are there \plausible\ planetary conditions where jet aircraft just don't have much advantage over propeller-driven aircraft?](https://worldbuilding.stackexchange.com/questions/175172/are-there-plausible-planetary-conditions-where-jet-aircraft-just-dont-have-mu) OBJECTIVE: A planet where propeller-driven aircraft are possible and practical and jet-driven aircraft are impossible, impractical, or at best offer no advantages over propeller-driven aircraft (and thus presumably won't be bothered with). I asked a similar question elsewhere, got mostly bad answers, but one stood out because it was the only one that actually met my criterion of "planetary environmental conditions" and that I couldn't instantly rule out: a planet with suitable elements to build internal-combustion piston engines but lacking useful quantities of suitable elements to make the high-strength alloys needed for practical jet turbines. [As others have noted](https://worldbuilding.stackexchange.com/questions/108323/what-kind-of-technologies-are-required-for-a-society-to-regularly-produce-jet-en), that seems to be the most likely limiting factor on jet technology. QUESTION: Is this a viable approach to the stated goal? That can be broken into two steps. First, can I actually achieve the desired effect (no jet aircraft) by this method, given known real-world science and engineering, or is there some easy workaround to a lack of said raw materials? Second, if the premise passes that test, is such a planet (surface) possible AND LIKELY, given what is known about geology and planetary formation? CONDITIONS: Piston-engined prop aircraft (or at least turboprop, but I'm aiming for piston). Not electric motors, etc. Thus, the planet's atmosphere has to support combustion in the first place. It should also support native (assumed oxygen-breathing -- I haven't examined that assumption, but I'd prefer to keep biology comparable to Earth) life. It does not matter whether it can support Earth humans (and I rather suspect it won't). [Answer] > > A planet without the materials to make jet engines — plausible? > > > ## No. Here's why. As someone said in the comments to your question, you don't need special metals for the alloys. It may disintegrate after several hours, but it will work. But putting that aside for now, let's say that you do want good alloys that will remain functional for long periods. What are these alloys made of? This question and answer is a start: <https://aviation.stackexchange.com/q/25645> Let's focus on one metal there: rhenium. Rhenium is already one of the [least abundant](https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements#/media/File:Elemental_abundances.svg) elements in the crust. Yet, humanity has found a way to extract it from concentrated deposits and make stuff out of it. This is a general point to be made for the entire periodic table. There are natural geological and physical processes that will occur on an Earth-like planet, that will lead to concentration of any kind of element into an ore deposit that can then be exploited. Completely removing an element is not possible. This would require changing the laws of physics, nucleosynthesis, planetary accretion, etc. You can also change the chemical conditions under which the planet formed in order to change a certain element more or less abundant. But that will fundamentally change how a planet works, and most likely break its habitability. Then, even if you don't have an element to make a jet engine, no one cares about it because the planet is not suitable for habitation. [Answer] ## NO: I'm not an engineer, but without specific metals, other alloys will be useable. Without metals, odds are some clever fellow will invent ceramic or plastic blades with similar properties but more/less expensive, and/or more/less reliable. But you might delay jet engine development by a century or two. There are several videos of guys at home building home-made jet engines out of scavenged junk parts. Actual high-performance prop planes were already starting to become ridiculously complicated by the end of WW2, using increasingly advanced materials to compensate. The [ME 262](https://www.airforcemag.com/article/0182engine/) went into production despite Germany's lack of the needed alloys. It did mean the engines only lasted 25-30 hours, but for a jet fighter, that could be sufficient. Any greater lack of metals will start to prevent production of steel all together, likely blocking prop plane development. Ceramics made of [silicon carbide](https://www.ge.com/news/reports/ge-develops-jet-engines-made-from-ceramic-matrix) are being developed by GE today to be lighter than the sophisticated alloys previously used. Not sure you can get a planet that supports 'normal' life building prop engines, while lacking silicon and carbon. so if the highest performance part can be replaced, then jets can be considered semi-inevitable technologically on a world capable of producing sophisticated prop engines. [Answer] > > is such a planet (surface) possible AND LIKELY, given what is known about geology and planetary formation? > > > Not if you have living creatures on it. To "build" living creatures requires elements beyond hydrogen and helium and once the universe starts making those you get, kind of as a by-product, the other elements we see on Earth. I'd suggest reading [Wikipedia's page on the composition of the human body](https://en.wikipedia.org/wiki/Composition_of_the_human_body). The relative abundance of elements is going to depend on nucleuosynthesis that preceeded the formation of the star and planets that has the life on it. It is extremely hard to imagine a planet having complex life not also having heavier elements in very roughly the same abundances we see on Earth. The way planets are formed means that they basically all get the same treatment - bombardment by meteors and collisions with other forming bodies along the way, as well as the creation of some elements by processes involving cosmic rays. The kind of materials used to make high performance alloys used in turbines are really not that complex in the grand scheme of things. Modern jet engines use considerably more sophisticated materials manufacturing processes than the early ones, but that's not going to prevent the development of early jet engines. The bottom line is that nothing exotic enough to make a basic jet turbine is likely going to missing from a planet that has life on it, because there's too much overlap in the way the elements required to make both are made. [Answer] A couple thoughts. 1. Jet propulsion relies on the ability to combust an oxygen-rich atmosphere. This is why a jet can't go to space without some alternate source of impulse, and why rockets carry oxidizers. So there might be room here, depending on what you're trying to do with a story. You could theoretically have an atmosphere that is not necessarily thin, and thus lift would still be possible, but with no combustibles in the atmosphere itself. However, it is possible to compress oxygen and carry it in closed tanks which would allow a jet to work. All conventional internal combustion requires oxygen to work. 2. I have toyed around with the low-metal-world idea for some years, and I keep coming back to the bio-availability issue with living organisms. Humans, and most types of life we're familiar with, just need too much metal to live to survive on a low-metal-world. You wouldn't be able to successfully farm anything, and anything you did wouldn't have the nutrients you need to survive, so you'd have to bring most of the metal with you, and VERY carefully reuse every ounce as it passed through the lifecycle of colonists. Even then, there would be some waste and loss, and you'd need to replenish it. 3. I do somewhat agree with the folks that say "well just use some other alloy". If the planet contains no iron, but contained chromium, tungsten, magnesium, and/or nickel, you should still be able to come up with an alloy that would work. If you don't have those, and no iron, you're not going to make much of anything that will stand up to high stress or heat in any application, you're going to be mostly limited by the weakening point of copper or bronze. Remember: human history is primarily the history of our ability to engineer fire. [Answer] This is totally possible. <https://www.livescience.com/15938-earth-precious-metals-space-origin.html> The earth has extra metal due to heavy asteroid bombardment. Normally heavier metals sink. On a planet which had less asteroid bombardment there could be a major shortage of the rarer heavy metals needed to make especially durable alloys. This would make it uneconomical to build jet engines. Not only would you need extremely expensive processes to extract the little heavy metals left, they wouldn't have enough of these metals to experiment with and develop appropriate high strength alloys. They could likely design jet engines, but their high failure rate with inferior metals would make them seem like a poor option. [Answer] > > "A planet without the materials to make jet engines — plausible?" > > > Some people said no, but we, human beings, don't know other planets to say so. The first jet fighter, the Me-262, had turbines which could work only for 10 hours. After 10 hours of use it had to be fully discarded. Only now, after more than 50 years of use, jet turbines have reached piston engines' fuel efficiency. > > Prop engines, on the other hand, are well suited for lower flight speeds and are considerably more fuel efficient than jet engines. They're also well suited for taking off from shorter runways. This is because thrust in these engines is created by torque rather than burning fuel. > > > We make use of jet engines because today, believe you or not, we have lots of fuel (petroleum). You can make a propeller plane using a steam motor, it is difficult, but it is not impossible. You can make a human powered propeller plane if you want. A steam powered jet engine on the other side is not a easy thing to do. I am not geologist, but I think that a planet where crucial raw material necessary to make a jet turbine is not available is possible. Just my bet. ]
[Question] [ What are the most important factors in determining how fast technology progresses? And roughly how fast might that be under optimal circumstances? Innovations have to be dreamed up, but there must be other more basic restrictions on progress. In the scenario below I’m looking for the most important reasons, why they are so important and an approximate time frame to the nearest century perhaps. Here is the scenario: A set of technical manuals describing in reasonable detail how to build every important technical innovation and describing every important scientific discovery from the last 2000 years has been written. This would include such things as steam engines, electricity, batteries, electric motors, gas turbines, vaccines, computers as well as an outline of the works of Newton, Boltzmann, Pascal, Darwin, Einstein and more. Technologies would be arranged in such a way that it was clear what the pre-requirements were, so electric motors require basic knowledge of electricity etc. Where necessary new words and concepts are defined in the text and diagrams are used. Now imagine thousands of these sets of books being distributed across the ancient world in appropriate languages (by aliens or some other hand waved out of scope mechanism). Copies go to all key figures in politics, religion, business and military affairs and further copies are hidden but in such a way that they are relatively easy to find over time. Roughly how much faster would technology advance? And what are the main hindrances to the rate of that advance? [Answer] As many people have noted, you need "the tools to make the tools", and the "book" you really need is "The Way things Work" and a lot of additional technical manuals. However, what might really be needed is not a technical library at all, but a book on economics. In the First century AD, Hero of Alexandria wrote a [book](https://rads.stackoverflow.com/amzn/click/com/1449562876) on mechanisms which describe what we would term simple atmospheric engines, low pressure steam engines and so on. The Romans also knew about water wheels, crank mechanisms and devices that we would describe as clockwork. Even farther in the past, the Greeks had the ability to create a mechanical astronomical calculator (The [Antikythera mechanism](https://www.smithsonianmag.com/history/decoding-antikythera-mechanism-first-computer-180953979/)). The Ancient Chinese were apparently aware of many of these things as well (I will leave any details to more well versed writers to answer). Going farther forward, we have fairly advanced (for the time) societies like the Hanse, building ocean going ships and trading across Europe from their ports in the Baltic, and the Serenìsima Repùblica Vèneta, another advanced society which pioneered "assembly line" production in the Arsenal, and concepts like "double entry" book keeping for their trade and banking networks. The first modern steam engine was patented in Spain in [1606](https://www.livescience.com/44186-who-invented-the-steam-engine.html). Despite all these advances, there was no "Roman Industrial Revolution", and we essentially had to wait for England in the early 1700's to "kick off" what we know as the Industrial revolution. England had a different social, cultural and economic system than any of the other societies which had developed parts of the Industrial Revolution as far back as 100 BC (the date assigned to the Antikythera mechanism). Ancient and early modern societies did not have the sorts of social or economic incentives that market capitalism does, and until the "Glorious Revolution" in England in 1688, social and political institutions did not explicitly place power in the hands of merchants, artisans and the middle class. This widely distributed and diffused social and economic system seems to be the major difference between England and all the societies that came before, allowing ideas to rapidly spread and providing the incentives to adopt and experiment with ideas. So ultimately it does not seem that a lack of knowledge or technology was the deciding factor, but rather the social and economic conditions that allow incentives for ideas to spread [Answer] For a technological advance one must have 1: Population density. This is a proxy for having (by luck) a person smart and clever enough to quarterback the innovations. I suspect that this was the limiting factor for many millennia. 2: Food availability. If your entire populace spends all of its waking hours trying hard to get fed, it is hard to expect any of these folks to advance technology in their spare time. They have none. Your innovator must be confident enough that he or she will be fed regularly to spend time on a long term project with an uncertain payoff. 3: Incentive. What is the payoff? The innovator who invests time and resources needs to see clearly how this is a better use of time and resources than hunting or farming. Will the mill run faster? Will the crops grow greener? Will she save sick workers from dying? Will the enemies of his king be handily slaughtered? [Answer] There's several factors that will come into play, but they all fall under one standard heading. I of course, am a fan of the less-standard heading put forth in the wonderful webcomic, Schlock Mercenary: > > If I have pissed further than others, it is because I have stood on the shoulders of giants. > > > Obviously the books are what you intend to use to stand on other's shoulders, but there's a few other things needed: * Trust -- People have to actually trust the book enough to go out and follow it. Frankly, if it were two hundred years ago, and someone described QM to me, I'd probably try to lock them in an insane asylum. Nevermind that we know now that it's a pretty good model. Its the insane asylum you go! On the other hand, if any of your cultures develop a religious following surrounding these scriptures of wisdom, they'll happily look for what's next in the book of truth. * Tools -- Just having a book isn't enough. You have to actually have the tools. You mention having a prerequisite tree, which helps. However, you still have to make the things. Consider the difference between having someone describe the branch prediction model in an Intel Core i7 CPU, and having the VHDL model of it. The latter would be gargantuan (speaking to AlexP's concerns in the comments about just how much material is needed). The latter really barely gets you started in making it happen. People still have to put in the elbow grease. * Technical skill -- You actually have to have the skill to do things. Some stuff you can learn in books. Others you can't. I can tell you about the optimum chip load for milling stainless steel with a given 3 flute bit, but it still takes a remarkable amount of training and practice to be able to achieve that optimum as a machinist. Many skills are this way. They're more than just reading books. They require teachers passing on an art from one generation to another. * Raw materials -- Materials matter. When America dropped a nuclear bomb on Hiroshima, it was the full extent of our available nuclear material. It was all we had mustered. Can't have a device without the materials that make the device. Some things are easy to find, but others, like oil or uranium, are a bit pesky. And they're also completely without value until the technology is in place to use them. * Desire -- You need a populace that actually wants science. My expectation is that if you gave these books to a group of Amish, they'd be very polite, thank you, and offer to give you a night's stay before you were on your way tomorrow. Then they'd toss the books away and go about living the life they want to live. Potentially the best case for this scenario is a continuous string of wars. Wars have a history of bringing out technological advancement at a rapid pace. [Answer] Existing viable workforce, existing technology, available infrastructure, average education. Less easily defined are things like current relationships between countries and the towns&villages within. Examples: during WWI these countries will not pool their resources to advance, but war does show a greater willingness to accept and use technology. You can have the requisites to build a steam engine, but if your populace doesnt have the education to know how it works they dont know when they do something wrong and will most likely fail building them properly or even know how to operate them. You can have the knowledge and facilities, but if you have but a tiny workforce of 10.000 people across the entire world (the rest is still busy with mostly subsistance farming) you arent going to progress very quickly. If the infrastructure isnt there you first have to build it. Our infrastructure is build on the infrastructure that went before. Just paint is made in factories that themselves are painted with paint from factories that went before... and now imagine trying to get uranium and other components for nuclear reactors without first having the infrastructure. As for the time it takes, it depends on all those factors. What is the willingness to embrace those technologies? (Or will you be burned alive for posessing such literature and using the technology?) The amount of people you can spare at that moment to learn the technologies and insights and teach these to the next generation? What is the current pool of resources and infrastructure to work with it, transport it, store it...? It is almost impossible to determine. [Answer] If I gave you instructions on how to build an engine what would you do? I can tell you what I would do, I would go to the store and buy the metal get my welding kit fired up and build it. this would not work in medieval times, you do not have any way to get the materials by either getting them and refining or outsourcing it. Getting them your selves. Medieval England does have factories in place to refine galvanized steel. outsourcing it, countries now trade for lots of there stuff lets take rubber as an example. To harvest rubber, a requirement in engines you need the rubber tree not native to 7th century England. lets say you build this car you need fuel. A peasant with a pickaxe cannot get you enough diesel to run your smithed together chevy. I,d say your time would be a quarter. as for the theories you have a new problem if I went to the Vatican and handed the pope the works of Charles Darwin I would be burned at the stake. Because of the need to first get the materials then build the machines to make the stuff if a society dedicated all of its time into id say a quarter if they dint then half the time. keep in mind guns would be the first thing anyone would build it would kick of medieval cold war. [Answer] Resources In your scenario, there's no need for intelligence, just rote learning. Once the people decide to follow these manuals (which isn't as likely as it sounds - but that's another question entirely) they'll run into a problem - the need for rare resources and metal. Black gunpowder is charcoal, sulfur, and saltpeter. Saltpeter isn't rare, exactly, but it's not common either. And the ways of gathering differentiate - if you live in Italy, for instance, there are caves of the stuff. If you live in Russia - well, that's a lot trickier. Thus, a civilization with access to natural deposits of rarer minerals and compounds will be able to progress faster up the tech tree than civilizations that live in the middle of barren and devoid lands. That's not to say that you can't eventually manage to make modern tech in those areas (though that may be the case for certain places), just a civilization with access to natural resources will fare better. Food isn't as large of a problem, especially since a lot early advancements can help the crops, and seeing as the incentive for mastering these crafts are the material comforts of the 21st century, the ruling body will have no problem demanding the scholars work as fast as possible, on the penalty of death. [Answer] Technology is really just finding ways to use oil production. Semiconductors are about the size of the plant to build larger devices, which build smaller chips. More oil means faster progress. If resources are unlimited you could probably advance from nothing to everything in a few months or years. China built a modern economy in about twenty years. [Answer] Politics Empires don't invent much new stuff because they're not in competition with other regional powers. (The British Empire was an empire in name only, just because of India.) Culture. Look what happened to Confucian China when the straightest path to success was to become an Imperial Bureaucrat and the Caliphate when his rule was threatened. Your culture has to value discovering how the world works instead of just accepting that's how God made it, and that His Will continuously powers the Universe. Climate Too cold, too hot or too dry, and you spend all your time trying to survive. Too wet and disease constantly ravages you, and stuff always rots. [Answer] If we're talking about predicting technological development, instead of designating something as the "cause", here are some fun spurious correlations: -Meat Consumption. More specifically haggis consumption, Scotland leads the world in per-capita research output. Meat consumption will be associated with both agricultural surplus and high average wealth (making a Malthusian catastrophe more difficult). Historically the only major brakes on meat consumption were religion, generally a factor restricting scientific development. -Navy Size. Takes wealth, certainly a factor. May indicate active conflicts, creating a demand for innovation (Get those old books out, maybe there's something in there we can use as a gun). Many play a role in overseas trade protection. Requires a highly centralised government. Would correlate more closely than money, war, trade or centralisation, despite not necessarily being causal. -Immigration. People don't tend to immigrate to poorer countries. Many historical developments happened in places receiving large quantities of (voluntary or displaced) immigrants. Mobile and educated populations will travel to wealthier places for economic reasons. Take northern Italy with the fall of Byzantium (craftsman fled the ottomans, bringing byzantine secrets) or the modern United States (over 1/3rd of the research in the US is conducted by the approximately 13% immigrant population) So raise malthus's limit, provoke trade conflicts and push tradesmen and artisans to regions where they are able to promote technological progress. [Answer] ## A middle class and social mobility You need a lot of people with: enough wealth to be literate, the free time to tinker and experiment, but also a reason to share what they discover/create and not just make one off curiosities. To get that you need social mobility (being an engineer in a caste system is not rewarding) But you say they have instructions why do they need to to experiment, because instructions are not good enough, it is impossible to create a perfect set of instructions, more so with people not used to thinking ins a rational logical manner. Impurities, errors, misunderstandings will happen. Without a fundamental understanding of science they have to build scientific knowledge alongside the technology, they need to be able to problem solve. this will be especially true of getting raw materials, geology requires interpretation. Ok but why not just the wealthy, the wealthy are great at creating one off curiosities but not great at seeing widespread utility, they tend to be either a, too far removed from labor to understand the process, or B disinterested in widespread implementation, the point of showing off wealth is about having things others don't so you don't want to share your secrets. A flexible middle class however can see useful individual gains from production and selling, they are incentivised to build and improve. You need people educated enough to see the implication of a technology but not so privileged they have nothing to gain from it. A final note you need these "manuals" to be so widespread they can't be easily hoarded, this will happen anyway in some places no matter what you do but as long as most places can't manage it technology will progress. [Answer] Connectivity , reliable communication and trade networks. Trade helps ideas spread from their point of origin to new places where they can fall into new hands and minds that tinker with them and add their own knowledge to the new concepts and inventions. Think about how the renaissance started in Venice which acted as a middle man between the Islamic nations, the Far East and Europe which led to many ideas and inventions passing from the former two to the latter which combined them to what would become the industrial revolution and the age of science we live in today. For a more recent example think about how increasingly specialised scientists are becoming coupled with the increasing complexity of our technology (creating a new pharmaceutical drug requires chemists, biologists, pharmacists and so much more ). Without the internet providing fast communications between far flung research teams around the world m technological development would be slowed just by the communication lag alone. Finally increased prosperity for the lower and middle classes who would have a stake in all the new technologies being developed, thus giving more incentive for innovation [Answer] # The number one factor gating the progress of technology is whether progress is gated on information. Moore's Law is the doubling of transistors in the same area every 24 months. An even faster trend is the [Law of Accelerating Returns](https://en.m.wikipedia.org/wiki/Accelerating_change#Kurzweil's_The_Law_of_Accelerating_Returns) - the amount of computation than can be purchased for 1,000 USD is doubling every 3 months. This trend has been holding across five paradigms of computation across 120 years. To put that in perspective - that means if that 120 year trend continues until 2030 then 1,000 USD buys you the computational equivalent of 1,000 human minds. That means that the iPhone X came out in 2017 and when the iPhone XX comes out in 2027, it will be as fast or faster in computations per second as the person's brain who is buying it. The reason that is important is that because once a technology becomes an information science - then its progress can ride the same curve that is doubling every 3 months. You can see these exponential trends wherever information is at the core of progress. For example, computers are now being used design computers in an ever escalating cycle. As for other examples - we are starting to see protein folding and receptors interactions be completely simulated in computers - and as a result are testing exponentially more potential medications than at any time in human history. We see this is simulated design as well - where computers are creating thousands of designs in seconds that used to take hours to days each. As a counter example, batteries and their complete physics and atomic interactions cannot be completely simulated in computers yet. The progress in batteries has been linear rather than exponential. Once they can be simulated, however, then the progress will be gated based on the progress of the Law of Accelerating Returns. Thus the single most important factor gating progress of technologies is whether and when it becomes an information science. ]
[Question] [ [![enter image description here](https://i.stack.imgur.com/2y9d7.png)](https://i.stack.imgur.com/2y9d7.png)[![](https://i.stack.imgur.com/fj1vd.jpg)](https://i.stack.imgur.com/fj1vd.jpg)[![enter image description here](https://i.stack.imgur.com/vFvN3.jpg)](https://i.stack.imgur.com/vFvN3.jpg)One of my main problems when it comes to drawing maps is how landmasses get distorted at different points. One of the continents in my story stretches almost to the north pole, but it looked very different when I projected it onto a globe; it was much thinner than I wanted it to be. Another one of my continents (located around the center of the world) appeared much wider on a globe. To people who draw maps, how do you account for distortion when going from a flat map to a globe? Update: Using the advice I've been given, I've updated my map. It's not complete (as the red sketch lines show), but it does give me a better idea of where things are. Any criticism would be welcome. Update 2: Included the finished version. I'll probably add more details to the landmasses eventually (the northernmost continent is much more detail than the others), but this serves just to give an idea of where everything is. [Answer] # I hope you like oranges The first thing you need to do is peel an orange. Now lay the pieces out in order in a rectangle. Doesn't work? Of course it doesn't, a sphere doesn't map onto a rectangle without major distortion somewhere. Now you could try drawing your maps onto an orange, but what you've really done here is generate an [interrupted map projection](https://en.wikipedia.org/wiki/Interruption_(map_projection)). These are the projections with gaps to allow you to reduce the distortion of the land masses. The [goode homolosine projection](https://en.wikipedia.org/wiki/Goode_homolosine_projection) is probably the best known of these. As you can see, distortion has been minimised, you can almost cut this out and wrap it back around a sphere. [![Goode_homolosine_projection](https://i.stack.imgur.com/fE0Nz.jpg)](https://i.stack.imgur.com/fE0Nz.jpg) The greatest disadvantage of this particular projection from your point of view is that it's cut out around the landmasses of our particular planet, so just taking the outline directly isn't necessarily going to work for you. But the principle remains the same, start by drawing on an orange. Peel it very carefully so that you don't break up your continents or island chains, then lay it out flat. As I said at the start, I hope you like oranges, you might be eating a lot of them by the time you're done. The [mandatory xkcd](https://xkcd.com/977/) has a few more of the more interesting projections, including a couple of interrupted projections. Though something as simple as a [sinusoidal](https://en.wikipedia.org/wiki/Sinusoidal_projection) or [robinson](https://en.wikipedia.org/wiki/Robinson_projection) projection may help with your distortion issue without getting overly complicated. [Answer] I have dealt with this problem many times. When it comes down to fixing a map you've already designed, while changing as little as possible, unfortunately you'll need to decide what is the most import aspects of the shape, scale, and distances of your world. To make it fit a sphere, it will need to be changed in some way. Consider my original map: [![enter image description here](https://i.stack.imgur.com/g8jcS.png)](https://i.stack.imgur.com/g8jcS.png) Pretty straightforward. Now look at what happens when I map it: [![enter image description here](https://i.stack.imgur.com/vtavr.png)](https://i.stack.imgur.com/vtavr.png) As you can see, the distortion at the poles in unsightly. How do we fix this? It depends on what you're willing to do to your map. For me, I shrunk the map vertically until the distortions disappeared. The following map adds 11% displacement above and below the land masses: [![enter image description here](https://i.stack.imgur.com/TyXb0.png)](https://i.stack.imgur.com/TyXb0.png) And the following result: [![enter image description here](https://i.stack.imgur.com/ocwzw.png)](https://i.stack.imgur.com/ocwzw.png) It already looks much better than before! You can even add a landmass at the pole if you want. And you can take it even further: [![enter image description here](https://i.stack.imgur.com/2cDut.png)](https://i.stack.imgur.com/2cDut.png) Which looks like this: [![enter image description here](https://i.stack.imgur.com/F8kf4.png)](https://i.stack.imgur.com/F8kf4.png) You might be saying "but I don't want my world to be all ice or sea!" but look at this. The following image shows the same projection, but viewed from the side of the planet instead of viewed from the pole: [![enter image description here](https://i.stack.imgur.com/lxKOJ.png)](https://i.stack.imgur.com/lxKOJ.png) As you can see, the ice is only just visible at the bottom and top of the image. Perspective is important! [Answer] You could do like GURPS and use an unfolded icosahedron ("d20") for planetary maps. Each triangle has very little distortion, and you can easily turn it into an icosahedral globus. Here is a map of the Earth done this way: [![enter image description here](https://i.stack.imgur.com/phc1F.jpg)](https://i.stack.imgur.com/phc1F.jpg) For regional maps, you can put any two adjacent triangles together as a rhombus (diamond) shape. [Answer] Free software like Blender lets you easily draw onto a sphere, and then unwrap to an equirectangular projected map. [Answer] Dispense with realism. [![roman map](https://i.stack.imgur.com/AMoEp.jpg)](https://i.stack.imgur.com/AMoEp.jpg) <https://earlychurchhistory.org/politics/the-roman-empire-china/> Depicted is a round map of the world, supposedly as the Romans knew it. This map has been much copied; I struggled but could not find where this image originally came from. If someone can find it please post link. In any case - you can make a fine map and not get undies in a bundle over precise topography. You could definitely use this map to figure place relationships in the mediterranean. Another good map would be one drawn by a character in your story - with familiar places and points of interest labelled prominently and drawn large and central, and further abroad landmarks and foreign cities more or less guessed. I like the idea of a map credited to a secondary character - perhaps a scholar encountered on the way. [Answer] I think you need to decide what you want this map for. If it's meant to help you with worldbuilding, it's more important to get the projection right. If it's meant to be used in-universe, like if a character in your story made it, it actually might make more sense to have it not to scale at all. Historically speaking, maps that look like a bird's eye view have been rare until the invention of aircraft. They're hard to make, and not that useful; people don't naturally navigate by latitude and longitude coordinates. Most pre-modern maps that people actually used in their day-to-day lives looked more like a bus route graph than a map. They would have been a tree, with landmarks marking the turns. "To get to Byzantium, follow the north road past Antioch to Tarsus, then follow the west road..." Here's an [example](https://www.historyhit.com/wp-content/uploads/2018/07/Tabula-Peutingeriana-Rome-map.jpg) of what I mean. This is a 13th century copy of a 4th century map of the Roman Empire. To be honest, that's still how most of us navigate usually. [Answer] The quality of a map depends on the society that creates it. If your world is swords and sorcery, then ignore "reality" and stick with maps that represent what the society knows and believes. If your world is early tech, then a mix of both "reality" and "classic" maps might make sense. If you world is spaceships and sky stations, then go with a globe. You might go with a variation of things. For instance, the world is actually flat, but some space flight is possible. Maybe space flight is not possible because people keep running into the dome of the sky. You could also go with a variation of map projection. For instance, draw the map on a globe then draw the land map the same on a flat map but accept that the oceans will be over stated. [Answer] Adding a new answer in order to respond to your new image. This one is much better! Personally, I think you should always work with an image with an aspect ratio of 2:1. This is a special kind of projection called the [plate carrée](https://en.wikipedia.org/wiki/Equirectangular_projection) projection, and this kind of projection has no distortion at all near the equator. During my original calculations, I thought that an image with an aspect ratio of 3.14:1 (or pi to 1) would be what I needed, since the circumference is pi times the diameter: --- [![enter image description here](https://i.stack.imgur.com/WBoYN.png)](https://i.stack.imgur.com/WBoYN.png) --- But I was wrong. Below is the result of an aspect ratio of 3.14 to 1: [![enter image description here](https://i.stack.imgur.com/EwOdW.png)](https://i.stack.imgur.com/EwOdW.png) And so I was scratching my head. So I looked at some Earth maps I had downloaded and saw that their aspect ratio was 2:1. So then I tried an aspect ratio of 2:1, as show below: --- [![enter image description here](https://i.stack.imgur.com/52VR4.png)](https://i.stack.imgur.com/52VR4.png) --- And it was a success! [![enter image description here](https://i.stack.imgur.com/T5JWV.png)](https://i.stack.imgur.com/T5JWV.png) ]
[Question] [ [Somewhat related question, but not the same goal](https://worldbuilding.stackexchange.com/questions/112309/what-can-be-used-as-a-money-in-a-high-fantasy-magic-world-where-noble-metals-are) In my current concept metals (from nickel to iridium, based on density) are used in the magic system. So in a way they are directly tied to power. I was thinking, that's a good way to have a "gold standard". (they are useful in many circumstances, helpful for achieve other (terminal) goals.) So I came up with rough conversion spreadsheets linking them to the price of a iron ingot (which is not included as currency, but useful nevertheless). Now, before I base my entire work (since this is woven really deep into my worldbuilding) on this (I have some doubts left), I got here for a reality check. More Info on magic system: - Magic can not be used to create things (So you can't create gold for example) - It can be used to accelerate growth/yield for example of food crops (but only to ~quadruple the crops or speed up the growth and nutrient and water use would still be that of the final yield. - No resurrection, only slightly better healing, no time travel and so on. - The most utility of using magic is to exert power (Warfare, Protection, Intimidation) - Metal is a necessity for the execution of any magic feat and is consumed in proportion to the power of the effect. Individual prowess dictates how much a single person can "convert" however. So you can't just consume a ton of copper :) General Info: - The tech level is late-roman in the cities to hunter-gatherer societies still in the stone-age in the outer reaches of my map. - Most bigger settlements and trading posts would have a way to measure the density of a substance (i.e. an ancient version of [a pycnometer](https://en.wikipedia.org/wiki/Gas_pycnometer)) - Coins of different worth are created out of tempered glass, and forgeryproofed via magic means, but they are only used in the innermost centres of civilization. They are basically a huge nuisance to reproduce (you need a complicated mechanical device and they have a magic fingerprint) so most people will not bother. Joachim: How are the coins directly tied to power within the magic system? - They exist for an easier flow of riches within the big cities and are basically a fiat-currency. People don't want to take big bags of weighty metals with them for larger trade deals. They are backed by the power of military (magic assisted) guilds. So in most civilized and half-civilized regions of my world goods and services are exchanged using small amounts of different metals. * Is there any big, glaring problem with that? * Do I need to come up with explanations why X would not happen? * Are there any loopholes left? * Do you need more info to answer the question? * I am ready to tune the availability of metals on the planet to fit the economy. What would be needed here? [Answer] The problem I see here is that it's not obvious from your description whether a single unit of any precious metal does the same thing for any person involved. From your description it seems that you want to have not a monetary system, but a barter system. I'm thinking here of your metals not as of currency, but rather as of a calculable unit of value. Something like a cow in northern European early middle ages. Not that they carried cows as a currency, but rather that they could convert a price of any given item to cows and trade with that in mind. (Say, a sword is worth two cows, two slaves are worth a cow, so you can trade four slaves for a sword). If your society is agricultural, and uses fertility magic - and if there is averagely the same result any mage can get from a fixed amount of metal, I can see it becoming a value measure. Say, a pound of copper is necessary for an average mage to make an average family plot of land fertile for a year. Then I can see this 'pound of copper' becoming a base from which barter values of all other items and metals are calculated. [Answer] Your currency is consumable for a purpose other than currency. That will affect its value. Magic uses up your metal. If metal is also your currency then that metal it has 2 roles and the one will affect the other. --- Suppose I want to buy chickens. I want to pay in metal. Big magic doings in my locality have consumed all the metal. I have none left to pay for my chickens. I trade for chickens by exchanging some good looking pants that I made. 2 weeks prior I had some metal. A magic user needed it for her magic. She wanted to buy it from me. But how does she pay? She can't pay with metal - she needs the metal for her magic! I invited her to trade me for it with wart removal services and a chicken. We traded. The metal is just another item and we are in a barter system. 2 weeks from now she needs more metal for magic. But metal is now hard to find! Now for the metal she needs she must trade 8 chickens and make a bald guy grow back his hair. The metal is worth more, because it is scarce. --- The good thing about metal currency in our system is that (except for some industrial uses) precious metal is not used up. There are gold bars in a Swiss vault that were once in Roman eagles and were melted and remelted over the years. If your metal is used up it becomes scarce and then less useful as currency. [Answer] Scarcity Before the discovery of the silver and gold mines in America and the development of fiat money, Europe was constantly short of precious metals for coins, to the point that [tally sticks](https://en.wikipedia.org/wiki/Tally_stick) were commonly used. Now, you somewhat alleviate the issue by allowing for more metalsmore on this later to act as coins, but you worsen it considerably by creating a process that consumes the metal (thus removing it from circulation). Also, while iron is certainly more abundant than gold and silver, it is not as if late roman technology was very effective at extracting it. They had iron, but it was not as abundant as today. Bad metals If Europe had scarcity of gold and silver... why did not they solve it by using iron coins? Well, previous metals are precious because they have some interesting properties, like being impervious to oxidation. An iron coin would not last long as such. This adds to the fact that to, for ease of use (and other reasons), coins were minted as a way of ensuring the weight and purity of the material they contained, so people would not need to weight and measure absolutely each coin that passed through their hands. But iron is harder to work into coins (less ductile) than gold, silver or copper, and as stated above any markings of the coins would be lost to oxidation rather quickly. [Answer] ### Deflation When you have a shrinking money supply, it causes deflation. It effectively forces the economy to shrink to match the amount of money available. I.e. people lose their jobs. In your system, the money literally disappears from the economy. This is a bad characteristic for money. Rather than a shrinking money supply, you want one that grows with the economy. Our modern solution has been money without intrinsic worth. We can therefore print as much of it as we need. Deflation is rare in modern economies as a result. Historically it was part of the business cycle. Every so often, there would be a shortage of gold followed by a depression. As described, your system is perpetually short of metal. People who have metal will get richer while people who don't get poorer. [Answer] I got here a bit late, so most of the points I wanted to make around having your metals consumed by wizard being an issue for your economy, have been covered already. Which is why my humble suggestion would be to cheat and introduce a non-reactive metal as money or value reserve asset. Perhaps this would be a metal with no magical application which, similar to gold, would be: 1. Sufficiently rare to be valuable 2. Sufficiently unreactive to stay the same over long periods of time 3. Sufficiently ineffective for other direct or practical applications, which make it a "social status" material (i.e., gold was not very good as combat armour but it sure looks pretty for detailing, jewellery or similar uses) 4. Sufficiently easy to store in convenient ways (i.e., using fragile materials would pose a problem for transport or safe storage, using bulky materials would consume a lot of space) Now, there are several ways in which such a metal could be introduced into your setting. I have done something similar to a setting I created, so these are my suggestions: 1. Have noble metals (i.e., gold, silver, platinum, palladium) be magically unreactive. This resolves the problem altogether, but may pose different questions within your magic system, such as why would these metals would not react to magic or behave differently. 2. Have a different material for money and value reserve purposes. This could be any metal really (provided it is unreactive to magic), or you could create a new one with some handwavium. It may well be that your world has an explanation as to why a non-metal material (at least in the real-life sense) that fulfils the previous list would be best to replace gold. 3. Have metals not be consumed by magic, but be catalysts for it. I do not want to intrude into your setting or magic system at all - just wanted to point out, as others did, that if for example, gold is consumed by mages, then it cannot be effectively used as currency. On the other hand, if gold would be merely coveted by mages, it wouldn't be different to what nobles and wealthy folk have done in the real world with it. Even though the question had already been marked as "answered", I hope this helps! ]
[Question] [ On a future battlefield where mechs are somehow the most preferred weapon system (over the far [more practical tank format](https://worldbuilding.stackexchange.com/a/10325/10364)), what kind of melee weapon is most effective? From human warfare, we see the evolution of weapons from swords to morning stars to hammers. The reason for the evolution in weapons is that swords became less and less effective against plate armor over time while concussive hits by hammers proved to be incredibly effective. (Then there were guns but that's outside the scope of this question.) Does this evolution hold true for giant bipedal armored combatants? Would an apropriately sized hammer be more effective in melee combat between mechs than a giant sword? If this does not hold, then why not? The mechs in question range in size from 5 meters tall to 20 meters tall and 6 tons to 100 tons. Based on [this question](https://worldbuilding.stackexchange.com/questions/52333/why-would-giant-mechs-use-melee-weapons) about why mechs would use melee weapons over ranged weapons. [Answer] The real problem with martial weapons is materials. A steel sword vs leather armor is effective. A steel sword vs steel plate... Not so much. The driving factor is that both weapon and armor will deform on impact. What you're designing for is to have the one that deforms last. The easiest ways to ensure that you win in the collision, is to add mass and carefully design the geometry to shape the forces of the collision to your favor. Weapons have the advantage of getting to chose where to apply the force of impact. The wielder gets to choose the point that of impact where the armor is weakest. For a mech, the weak points are similar to a person in plate armor: the joints. Aiming a sword into the crack of a join to muck up the workings inside requires speed and accuracy. But you don't have to get inside to stop a joint. You can bend it just enough it can't move. Enter: mass weapons, i.e. Hammers. Beat on the joints till you break something, or bend it enough to stop moving. In modern armor combat, this is called a mobility kill. [Answer] Your mech should use a hammer, but not a sledgehammer that it swings around with its arms. That is the best humans can do but you can use tech to store energy and then release a tremendous amount with each blow. The hammer should be a pneumatic or hydraulic hammer: it will store energy as pressure then release it with the impact. Hammers like these (jackhammers being a good example) are routinely used for demolition. A jackhammer releases the energy as multiple small hits but you could release it with one big hit. You hammer will need to restore pressure after each hit. I am a little worried about a "dry fire" - if the hammer piston does not impact anything before reaching the end of its length the energy will need to be absorbed by the hammer housing which is less than ideal. You could have some braking mechanisms, ideally regenerative to capture this energy in recompressing your working fluid. Or you could side step this (perhaps in an ad hoc manner!) by untethering your piston and allowing it to continue completely out of the hammer. It might impact something farther away. You could retrieve it later if things go well. [Answer] People have already suggested hammers so I think I'll take an alternate tact. Spears Hammers are tremendous weapons for inflicting huge, crushing blows on enemies. Unfortunately, they are slow and unwieldy compared to many other melee weapons. What you can't hit you can't hurt, and the downside to swinging large masses around is that, given a miss, there is still a lot of momentum carrying on. If the goal is to limit the mobility of your opponent, spear weapons can make a lot of sense. Spears allow you to thrust quickly, to concentrate a huge amount of force on a very fine point, and to do so without over-extending yourself and opening up to a counter strike. Tweaks for Mech Combat Furthermore, a spear can be more than a spear. Depending on your rational for melee-exclusive combat, a spear can act as a delivery system for more advanced weaponry. A spear could pierce a Dunesque Holtzman-Effect shield and then deliver an explosive or plasma charge. A spear could pierce the electrical shielding on the outside of a mech in order to deliver a debilitating shock, a jet of conductive or acidic liquid, expanding foam, or hell even a computer virus (injecting code indeed). These type of attacks would lend even more safety to spearfighting, as the strikes could be made with very little force, quick, darting jabs that are accurate and easy to retract. Harpoon Style Furthermore, it may be a good tactic to use a harpoon. With a classic [Whaling Harpoon](https://raw.githubusercontent.com/active9/harpoon/master/files/default.png), you could stab your enemy with a weapon that would be difficult or impossible to remove. Thus, you could keep hold of the weapon and use it to pull the enemy off balance, or you could let it go and have its weight, damage, and overall unwieldiness hamper your enemy while you draw another spear to finish them off safely. With a hooked harpoon, you could disarm your enemy, catch then with the hook part and pull them off balance, or pull down their shield if they carry one. Conclusion Spears are simple, adaptable, and deadly weapons. They are easy to use and have a high skill ceiling. They allow your soldiers to maintain distance while in combat, keeping them safe. Mechs equipped with spears could even fight in formation. Hammers are great and all but they have very significant drawbacks; There is a reason why spears are the weapon of choice for infantrymen for most of human history. [Answer] # Definitely hammers Hammers do a lot more damage over a greater area allowing for less accuracy being needed with them than with swords. Plus Hammers can have one side that can be pointed allowing for piercing if it is needed, but swords cannot have this dual functionality. But swords do have some upsides when compared to hammers, especially sledgehammers. Swords aren't as heavy and are more precise on targets and are faster than hammers. But when compared with all the damage hammers can do and the fact that your fighting with big metal monster machines, a hammer, especially a sledgehammer is better for those types of battles. Also a good reason for using melee weapons is that they last longer and you don't have to sore a bunch of projectiles to use your weapon. Or you could say it's a cultural style to fight like that, just like how the British used formation in the American Revolutionary War battles partially due to culture and how the Europeans fought. [Answer] So the question here is can you make a sword out of a material hard enough to penetrate the mech's armor. Hammers, as effective as they are, are not quite the weapons they appear to be on paper. Sure the concussive force they apply is great, and it's very hard to protect against them, but have you ever used a sledgehammer before? Hammers aren't exactly fast, and a bad swing will leave you open and possibly even off balance. You also have the problem of range because there is a very specific distance that the hammer will be effective from. Any closer than that and its next to useless. A sword's biggest problem is penetration, as you mentioned. However, swords do carry pretty significant amounts of kinetic energy themselves. Get hit with a wooden training sword and see how easy it is to just walk it off, (spoilers, it's not). Also, you are talking about mechs here, a sword that big will be very heavy, and if your mech can swing it fast enough to use as a sword then every hit will have a lot of force behind it. Unlike a hammer, the distribution of mass on a sword makes it much easier to swing and recover from, and you are less likely to be put off balance as long as the blade isn't ridiculously huge. A sword is able to do a number of jobs, from slashing, slicing, stabbing, and yes, even bludgeoning. However, swords also take more skill that most weapons to wield effectively. The reason samurai were so feared is because they were incredibly hard to beat in one on one combat, and the reason they were comparatively rare is because it took years to train them to that level of skill. So with that in mind, it's a question of skill and material. More skill and higher quality materials, sword. Less time to train and lower quality materials, hammer. [Answer] I think most people are focusing on swords for slashing and neglecting the stabbing option they bring. People also are focusing too much on the comparison between mech and plate armour on a person. On a person, chop off an arm and the fight is decidedly over. But with a mech pain and blood loss isn't a problem. Commonly in mech design there is a glass cockpit for the driver to see out of. Even if not glass it would be thinner metal. A rapier type sword could be incredibly effective at poking the driver from range in a spot that's quite vulnerable to it. A rapier can maintain distance from a hammer easily and effectively attack the weakest point of the mech, the driver. It can also be used to poke at the joints, and while a human wielding a rapier against plate armour isn't very effective, keep in mind a mech would have a ton more force behind it. Sword techniques also developed to combat armour, such as bashing with the hilt. I think primarily the rapier on driver strategy is the best tactic, but that using the sword to stab at joints would work well, and the mechs could even have the strength to chop off parts with a sword. [Answer] You might want to take a look at Front Mission's "Pile Bunker": [lostplanet.wikia.com/wiki/Pile\_Bunker](http://lostplanet.wikia.com/wiki/Pile_Bunker) [img.amiami.jp/images/product/review/104/FIG-IPN-1356\_03.jpg](http://img.amiami.jp/images/product/review/104/FIG-IPN-1356_03.jpg) A hand mounted pneumatic spike that gets released quickly with some type of gas. It would be more effective than either a hammer or a sword for mechs as it would release a great thrusting force over a small area, which makes for a very effective pierce. It's not as flashy as a hammer or a sword, but it's certainly more effective. In fact, even a giant metal baseball bat would be more effective than a sword in a battle of mechs. Because the sword is made for cutting. However, a giant mech is probably made of a very thick metal armor. A giant sword would, at best, only make a notch in the armor. That's without taking into consideration a mech's armor might be sloped, making it harder to land a propper blow, not to mention the body itself moving around, further reducing the cutting power of an incoming blade. Using a giant bludgeon, you wouldn't focus on cutting, instead on transferring the full force of the blow onto a mech. Much less chance of a glancing blow, with more force transferred with the blow and with the same handleability as a sword. [Answer] OK, while giant mechs are silly, there are some memes which will not die. Space fighters is another one. So, in order to destroy or cripple an enemy mechanized vehicle, which is presumably armoured like a tank, with a physical blow would require a very large and fast moving object to strike it. (edit: to put this in perspective a 105mm APDS projectile [common on 1960 era tanks] struck with 13 million foot pounds of energy). A lot of momentum is going to be generated by the fast moving object, and if you hit, the momentum is abruptly stopped, with some adverse consequences for the person or machine swinging the object. If you miss, the momentum will likely carry you past the object you swung at, which is also not a great thing when involved in hand to hand combat. So what you want is something which can dissipate the striking energy in a way which is not detrimental to the mech doing the strike. I would suggest a flail or chain weapon. [![enter image description here](https://i.stack.imgur.com/WjlGX.jpg)](https://i.stack.imgur.com/WjlGX.jpg) war flail Now there were lots of variations, but the essential thing is the striking head(s) is attached by a short chain to the handle. The full force of the impact is not being directly transmitted back to you, and a return stroke is much easier than with a solid weapon like a war hammer or pole arm. The chain is also versatile enough to be used to entangle the opposing mech's limbs, and the weapon can be reversed and the handle used as a bludgeon if needed. Of course, if you are really that close, then you are in pistol range. A mech could have the equivalent of a giant claymore mine strapped to the chest armour to detonate when close to an enemy mech. Or you can just call your space fighters down to strafe them..... [![enter image description here](https://i.stack.imgur.com/f9Wkg.png)](https://i.stack.imgur.com/f9Wkg.png) This is how you deal with mechs [Answer] TL;DR combine the best of both (or make a giant halberd, possibly). A "sword" on the scale you could carry on a mech is not the same beast as a hand-held one. It needn't even be especially sharp. If you go for a nice solid square or diamond cross-section you'll have two or four somewhat-pointy edges and can deliver what amounts to a hammer-blow, but slightly more focussed. Another way to look at it, is how can you make a hammer a bit longer (targetting has a little more leeway) and pointy (for those attacks on the enemy mech's joints, power conduits, hydraulics etc.). Edit: I'd overlooked @John's comment on war hammers being made pointy. No stealing intended! [Answer] Depends on how your mechs look. Do they have exposed hydraulic lines or control wires that can be cut? If so, then a cutting weapon like a sword may be very effective at disabling a mech instead of bashing it up. Very important if survival of the pilot or salvaging the mech is important. For example, lots of medieval melees were not to the death, but "to the surrender" of an opponent so you could ransom them back and keep, sell, or ransom back their gear. You can't do that if you killed the pilot and destroyed their stuff. A weapon like a pick, or a war hammer (long shaft, small impact head backed by a spike) would be ideal for punching through armor or hitting critical actuating surfaces, sensors, and power systems. Movies like Pacific Rim show mechs with little in the way of actual mechanical parts, they are basically just men in armor. But real mechs have lots of areas with pistons that can be bent, hydraulics that can be cut or broken, and engine systems that won't react well to a hammer smashing a power cell or rupturing an oil reservior. The piston punch is probably the most practical melee weapon as it would be easy to incorporate into a mech for those "just in case" melee encounters (so more like a bayonet to attach to a rifle than a dedicated polearm or sword to carry around) while firearms are the weapon of choice for warfare. [Answer] To know what kind of weapon, we need to know how agile are your meka not agile mech These type of mechs have a lot of limitations in their arm movement. Forget about swords, you won't be able to move quickly enough to slash properly. Same thing for a classical warhammer. [![Warhammer 40K Dreadnought](https://i.stack.imgur.com/LB9b6.jpg)](https://i.stack.imgur.com/LB9b6.jpg) but using a kind of pneumatic spear (like this ) you would get a real goot penetration capacity and, if you ennemy is as agile as you he wont be able to dodge. with a bit of skill you can easly target the pilot, or weapon system and destroy your target in only one blow. [![Librarian](https://i.stack.imgur.com/4MC8V.jpg)](https://i.stack.imgur.com/4MC8V.jpg) Nearly as agile as a human In this case, you have a lot more options for your gear because of the greater freedom of movement. Using a pneumatic weapon could still work but it wouldn't be the best choice because if you aren't stable on your feet, the recoil could knock you off balance. And you can't have that. If your opponent is able to dodge and land a deadly repost right away because you are not ready to dodge. But, a hammer (see below) would be way more interesting as it can deliver a piercing blow to the joint of the enemy mech. This could disable your opponent or even kill the pilot if you land a shot by luck. Even if you are not able to pierce the enemy armor, the strike can cause a lot of vibration and maybe cause incapacitate the pilot or damage internal systems. [![Warhammer](https://i.stack.imgur.com/DPkPM.jpg)](https://i.stack.imgur.com/DPkPM.jpg) In any case, a sword doesn't seem to be a good option to me as long as the blade can't slice through armor. Stay with piercing weapon, it would be easier to make deadly in a mech battle. ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/90826/edit). Closed 6 years ago. [Improve this question](/posts/90826/edit) What I had in mind was a huge being (moon/planet sized) that lives and moves through space, now could a living being do that? Maybe it could feed on light and radiation from stars? And would a being be able to move in the vacuum of space, if so, how? [Answer] Yes, surely. Although they would be vastly different from those we know, it is perfectly possible for a living being to have a skin comparable to a spacesuit, or a hard, ship-like shell. They could 'photosynthesize' (although not exactly the way plants do) from stellar light, but probably they would still need to consume asteroids (and spaceships) to take in material and grow. They could move with some type of reaction engine (rocket). It could be a simple pressurized gas forced out, chemical rocket, electric engine, or biologic mass driver, (a hand throwing stones). So theoretically it is possible, but it is hard to imagine the biology and evolution of such a being, and some part of it would resemble 'technology' more that 'life'. [Answer] Freeman Dyson postulated a "[Dyson Tree](https://infogalactic.com/info/Dyson_tree)" planted on the core of a comet and extending outwards into space to extend light gathering leaves or some equivalent photosynthetic organ. Humans and animals could live within the bodies of the trees as symbionts, breathing the oxygen and providing carbon dioxide and nutrients in the form of wastes. In theory there is little to prevent the Dyson tree from growing to any arbitrary size, and the tree can use light pressure on its leaves to slowly move about in the reaches of deep space. [![enter image description here](https://i.stack.imgur.com/Y7vub.jpg)](https://i.stack.imgur.com/Y7vub.jpg) A forest of Dyson trees near a planet [Answer] Tardigrades, also known as "water bears," are microscopic creatures known to survive extreme conditions such as vacuum, extreme cold (1 degree kelvin) extreme heat, ionizing radiation... [Answer] Earth is a "living" being. Kind of. At least if you allow some freedom in the definition of "live". While it is clear that Earth contains living beings which fed on sunlight (photosynthesis->plant->animal), you can also view Earth itself as some kind of organism ([Gaia theory](https://en.wikipedia.org/wiki/Gaia_hypothesis)). If someone here cringes for the word "organism" and imagines new-agers with peace symbols smoking weed bowing to a natural godess, you can replace that with the more technical term: "feedback loop". Planet-sized beings (at least encompassing a whole planet) are to our current knowledge impossible. After a few kilometers depth the pressure deforms anything living in solid material and solves too much disinfecting gases in fluids, so that does not work. This does not mean that living being can grow to gigantic sizes: The USA has a gigantic honey fungus in the Malheur National park in Oregon which has a weight of over 600 tons. Small living things can survive in space. Small living things like microorganism are in fact able to survive long periods in vacuum and radiation. We have found by experience that in the capsules microorganisms feel quite well and build [biofilms](https://en.wikipedia.org/wiki/Biofilm) which are very resilient, some types of microorganism are extremely resilient even against radiation and vacuum and could theoretically survive being pushed in space in a meteorite by an impact and survive reentry. [Answer] I am not sure it would fit your criteria bu imagine an earth-like planet covered by a single large organism. With the planet's mass it could have it's own atmosphere and possibility a magnetosphere which would protect it from space. Like all life on our planet it would have to absorb energy from the sun and use material from the planet to form itself. It would probably not be able to move itself. If you want a deep space organism you are going to run into the problem of lack of energy and lack of matter to convert into tissue. As a side note if you want a organism which has grown to the size of a planet it will have to have consumed a planet worth of matter but most of the interior matter could be non living in the same way much of the tissue in the centre of many trees does not have any biological activity but provides structure for the living part of the tree. [Answer] ## Unlikely for the size Life finds a way of adapting, living in the vacuum of space wouldn't be kind on creatures who have evolved to a gravity but I dare say life could find a way. However you need the material to grow and become planet sized. On earth plants use the carbon in the air and nutrients in the soil to grow but if your creature is planet sized (not just something living on the surface of a planet) then you need to acquire all that material from somewhere. Space is largely empty so I can't imagine it being very likely a species would survive if it relied on finding that much material to grow. [Answer] Very much depends upon how you define a living being. Humans, with special suits can live in space, with protective shelters and special nutritious foods in packets. What you're imagining is a living being that survives on light, can travel through vacuum, and is the size of a planet or moon. While I've never heard of such a being yet, we can't rule out any possibilities. There might be "living beings" out there in the ocean of stars. So, currently, no, there appears to be no such a being. But who knows what's out there! Such a being would have evolved to survive on radiation. See how our trees feed on sunlight. Such a planet sized being would've evolved in a way that it can adjust its shape, or eject mass from its own body to aid movement in vacuum. It might be orbiting a star somewhere, and we might have even detected it but didn't know it was a living thing. [Answer] Because one of the criteria to being alive is breathing, no living object can be alive in a vacuum. However an object with the size of a planet could keep its own air around it. Keep in mind that said planet would have to be big enough to actually have an atmosphere which means that even something the size of our moon would not be able to live in space. ]
[Question] [ Inspired by [Bonegrass](https://worldbuilding.stackexchange.com/questions/38354/how-often-must-carnivorous-grassland-eat) and the local [sawgrass](https://www.nps.gov/ever/learn/kidsyouth/sawgrass-prairie.htm) I've started thinking about a new creation... Bloodgrass. Bloodgrass typically grows along the edges of watering holes and streams in tall dense thickets (approximately 3-5 feet tall). Bloodgrass looks, at a distance, very much like other tall grasses, but upon closer inspection the blades are incredibly thin. Don't inspect it too closely. And under no circumstances should you touch it. Bloodgrass when touched by an unwary animal is known to suddenly and inexplicably coil around the unsuspecting creature, as the animal struggles to get free the thin wire like blades of grass cut into the flesh... bleeding profusely the animal begins to struggle and is further ensnared as it touches more blades. Should you stumble into a patch of bloodgrass, Don't Move. The grass's spring like coil won't be sufficient to cut you badly. Your only hope is to Remain Calm and Wait For Assistance Bloodgrass is thought to have initially developed its bloody trap as a defense from herbivores, but the adaptation thrived as the plants that used this trick were substantially better fertilized. --- This is more or less a reality check question, is this plant believable? Also... How could the grass quickly go from a long, straight, thin blade to a fairly tight coil and then return to its original straight form after killing? [Answer] It is believable up to a point. Stronger animals should be able to pull free and some larger animals should have strong enough skin to withstand the grass with only minor scratches. However, if the grass can work even with those restrictions, I have one other nasty to add to it. In southern California, we have an invasive species that is locally called "lion tail" or "pampas grass" it grows 1-3 meters tall before the weight of the fronds cause them to droop. It has one thing that most people don't know about. The leaves are covered in an oil that is an irritant. If you are cut by the grass, the cut will itch and burn. If you add that to your bloodgrass, victims will have a hard time calmly standing still. I lived by that stuff when I was a kid and used to use it as a hideout. The trick is that the fronds only cut when you move your hand away from the base of the frond. So, when you grab or touch it, you must always move toward the center of the frond. Being careful with how you handle it will allow you to move through a patch unscathed, even if you are in short pants and short sleeved shirts. So there might be some smaller animals that live in the bloodgrass that will pre-digest the food for the plant. [Answer] The bloodgrass using the blood as fertilizer is the only issue I see. There are plenty of plants that have moving parts (<https://en.wikipedia.org/wiki/Mimosa_pudica>) and plenty of grasses that are unpleasant to walk through (the pampas grass mentioned above, and i can vouch for many sedges having sharp edges) So just combine those and you are good. But ultimately this comes down to risk vs reward. For many carnivorous plants the only reason to go through the effort of catching prey is the extra nitrogen that unwary insects provide. The plants focus on prey that is easy to overpower on the limited energy budget that a nitrogen-starved plant has. Some pitcher plants occasionaly catch mice but those are the exception to the rule. So basically the expended energy has to be balance against the amount of nitrogen gained. And blood doesn't contain a lot of energy until you completely bleed the animal in question and if that happens you get a corpse, which contains all the nitrogen you could ever need. But that now-corpse might do a lot of damage to your leaves while it bleeds out because that is not a quick death. And you need to do this in a nitrogen starved environment because otherwise you get overtaken by the plants who don't bother with all that "hunting" sillyness. So a grass that is sharp enough to seriously hurt? Yes That moves towards movement? Sure. That uses blood as a serious part of nutrition? Not sure. [Answer] It does not need to have the strength of steel to cut. Fiber is strong enough to inflict [Paper Cut](https://en.wikipedia.org/wiki/Paper_cut), adding poison, or nastier, bacteria to quicken death. The bacteria lives symbiotically with the grass. It will inject strong [anti-coagulant](https://en.wikipedia.org/wiki/Anticoagulant) that gives the name of Bloodgrass, where the patch of the grass is often covered red by the blood of its victim. I doubt the coiling will be both strong and fast enough, because strong means thicker vine/leaf, and thick usually means slow. The closest plant I can find is [Sundew](https://en.wikipedia.org/wiki/Drosera). Animals can break free from the coiling, but the sharp edge will cause more cut, and making the wound area larger. The vine/leaf will return to original form for the same reason other plant with [Thigmonasty](https://en.wikipedia.org/wiki/Thigmonasty) , that is turgor pressure returning to normal value. [Answer] > > is this plant believable > > > "Reacting" plants already exist ([Mimosa pudica](https://it.wikipedia.org/wiki/Mimosa_pudica) and, even more, [Dionaea muscipula](https://it.wikipedia.org/wiki/Dionaea_muscipula)) and it is very easy to evolve thorns and blade-like appendages. There are plants that develop enhanced grappling powers with the purpose of hitching a ride (or allowing their seeds to hitch a ride) on the local furrymobiles. So it would have begun with a thorny plant being fertilized by blood, and the thornier, the more cutting and more aggressive the plant, the more blood it would have harvested. Silica-enriched blades are not uncommon either. Bloodgrass is therefore perfectly feasible - it's almost guaranteed to catch the fancy of some botanist on Giedi Prime - and it would work. But is it really convenient to go for the kill? The kill is not going to be instantaneous, and a beast might tear up a lot of plant in its struggle to free itself before dying. True that this would yield a lot more fertilizer, but the cost might be excessive. The simplicity of it all almost guarantees that if it was really advantageous, it would have already evolved. So you need to come up of a way in which the "fertilizer" is a real boon to plants, and yet they still can thrive without. As a compromise the grass might have a specific breakpoint so that an animal too small to be dangerous is retained, but a larger prey - unless lame or sick - can escape without too much of a struggle. This might allow an intelligent creature to attempt escape by breaking the grass blades one at a time rather than tackling them all together. ]
[Question] [ Imagine the population of our planet is given free (almost) and unlimited energy. What kind of technologies would go mainstream which are not feasible today due to prohibitively high energy requiremnts? What would happen to our environment with 12 billion humans 'high' on unlimited energy? What would our planet end up looking like when obeserved from out space? Would 'everybody' end up owning a space ship? [Answer] ## Earth with unlimited amounts of cheap energy: [![Earth](https://i.stack.imgur.com/cPrWX.jpg)](https://i.stack.imgur.com/cPrWX.jpg) With that much energy, it only takes one idiot to melt the Earth. On the upside, we'd probably be godlike by our present standards, so humanity will have long before diffused across the universe. [Answer] By the standards of a century ago, that's the world we're living in. By the standards of a century from now? Who can say. Imagine a world where a horse is the ultimate source of power, let's call that one horsepower (1 HP, 745.7 Watts). A horse can do a lot of work but not fast. Now take a person who knows only horses and put him in front of the engine in a cargo ship (81 MW, 108623 HP [Emma Mærsk](https://en.wikipedia.org/wiki/Emma_M%C3%A6rsk)) and tell him we're not living in an era of cheap almost unlimited energy. [Answer] Large-scale recycling would become feasible and cost-effective. Recycling currently has a high cost: picking and sorting refuse, transportating refuse to a recycling station, and transforming it (chemically, physically, biologically) to something usable by the industry. With much cheaper energy, the two last processes cost much less: heating, cooling and moving, useful in all transformation industry, are energy-based. Recycling, by its turn, would solve a bigger problem: scarcity, and one-source dependency, of some natural resources, like [rare earth](https://en.wikipedia.org/wiki/Rare_earth_element#Global_rare_earth_production) elements. And that would shake the world's geopolitics. [Answer] * Fresh water everywhere. Desalination needs energy. Make energy freely available and you can desalinate sea water and transport it very far. * The end of air pollution. Most of air pollution comes from generating energy, either locally (in your car engine, cooking food) or regionally (making electricity and heat, industrial use of energy). This in turn leads to increased human health (air pollution kills millions of people per year). * The end of famine. Making fertilizer requires energy. * The end of global warming. You can capture CO2 and make fuel of it, if you have energy. * Increased industrialization. The industrial revolution happened because (among other things) energy became available. If energy becomes freely and cleanly available, we can expect the Industrial Revolution 2.0. All of these things combined lead to... * Less war and conflict. Those conflicts that can be traced to scarcity of resources (oil, water, food) are made less likely with free and clean energy. [Answer] Unlimited and (almost) free energy (in a form that is directly usable, from a wall socket or a fuel station) has fantastic potential. Ideally, it woult change earth into a post-scarcity society. Practically everything comes down to energy. The food we eat is chemical energy, and required energy in various forms to grow, to be harvested, transported and processed. Heat is energy, as well as light. Every object you possess was made using energy. So, in short, with (almost) free energy, almost everything is almost free, too. The only potential problem is that whenever you have people, you will always have some who want to have more than others. That means tehre will be some people who would prefer if not everybody had everything they need for free. But personally i hope that the availability of a post-scarcity society would get enough people to defend it from those too greedy. EDIT Following @sdrawkcabdears question: With that much energy so cheaply available, and provided that the benefits of this are not pinched by a small group, it seems safe to assume that global birth rates will drop. This follows an observable pattern that shows that the more educated women are, the lower the birth rate. Education is easier to get once you have energy. With lower birth rates one can assume that global population will not grow too much from current levels. As a result, the amount of things people need can be regarded as limited. With enough energy very cheaply available, mining, refining and recycling operations get easier. The (finite) global population will never need an infinite amount of things, especially when you recycle the waste. So, having enough of everything for everyone boils down to having enough energy and a few hand fuls of smart people coming up with handy ideas about how to make the things people need. This part should be laughably simple, when you have 8 billion people who are not fighting for their survival. [Answer] It very much depends on what kind of energy it is, and what we do with it. Unlimited energy means it has to come from somewhere, and go somewhere. Solar is the obvious candidate for an unlimited energy world, with the day far away when we ever have any scarcity of solar. But that doesn't mean we'll have unlimited resources of everything else and 100% efficient machines. Even if we assume every single machine runs on electricity which we can cheaply convert from solar, they'll dump heat into the atmosphere, driving up temperatures. Also, demand for materials will shoot up which enable us to store and utilize electric energy(such as Li-ion batteries). On the bright side, comfort level of people will increase. Today electricity can be converted to almost any other form of energy - heat, cold, magnetism, fuel, anything. That'll help people get comfortable where they live - and it'll be widespread as even the poor will be able to use the energy. Mankind will have a more sustainable future than what is there today. We could control or even reverse the greenhouse effect, reduce pollution and eventually eliminate it, build high speed transportation to anywhere in the world, build energy based shields for large scale disaster control. Another use I can find is high-speed space travel. Assuming we can store and use huge quantities of energy in spaceships(developing the ionic engine concept), we could achieve near-lightspeed travel. That could allow us to inhabit and mine other planets. So to summarize, it could lead to elevated temperatures(atleast unless we find a way to dump that excess heat), put a strain on other resources as the resource use per capita increases, but aspects of life dependent mostly on the energy we use will see a significant benefit. [Answer] user16295 has a great answer. Availability of energy is one of the most important things for technological progress. So unlimited energy will boost our technical capabilities. We would start heavy space travel, maybe terraform Mars, we would build huge buildings and ships. Basically everything we would do anyway in the future. So the answer to your question is: the word would experience a very fast technological progress. Some follow up questions to consider are: how will the unlimited energy affect earth? This depends on how we produce it. Out of thin air? probably not. Will environmental pollution and destruction be a thing? will we get the energy from other celestial bodies? Is the energy transportable? (it helps nothing to have an fusion reactor sourcing a bazillion terrawatts if you can't fuel your spacecraft with it) [Answer] One practical thing that occurs to me is the usage of aluminum. It is more abundant than iron, it has higher specific strength than steel, it forms a oxide layer which prevenst from rusting, it has a lower melting point making easier to work with and it is easily recyclable. The biggest problem with aluminum production is the energy necessary to extract it from its mineral. Having that solved, imagine: * Buildings done with aluminum alloy could be easyer to built and could be taller, * aluminum bridges without necessity of being painted, light cars, ships, trucks, trains, etc. And all that without much of oxidation and recyclable. Cheap aluminum alone would make the Earth way more abundant. [Answer] Tagging on to some of the other answers, having cheap, unlimited energy would be a great boon for technology. The part that hasn't been mentioned, however, is the finite level of other resources. One of the main issues your new world will have is figuring out what they are using to make the physical objects. Yes, we can travel to space using the new energy, but we still need steel and iron and all of the other materials that go into creating a space ship. You are going to have a lot of waste from people determining how to convert current objects to use the new energy. The form that the energy takes will determine how many different products need to be adapted (cars, for instance, will almost certainly need to be changed to use the new power). Also, is your new energy clean? Coal, for example, is pretty cheap, but burning it has a lot of [environmental downsides](http://www.ucsusa.org/clean_energy/coalvswind/c01.html#.VrDxGcArJQI). If your energy isn't clean, organizations will either need to enforce environmental standards or the use of the energy will make living more unpleasant over time. [Answer] What does thermodynamics say? As others have mentioned, the source of energy affects the scenario. So let's assume energy is produced by invisible pink unicorns that run around in some fields and just magically put essentially boundless amounts of electric energy into overhead power lines. Now you're going to use the energy to do something. Since energy is never created or destroyed (pink unicorns notwithstanding), it will not disappear when it's done what you wanted. Instead it turns into waste heat. Today we use about 700 exajoules per year. If we increase this by a factor of 10 000, the waste heat would be about equivalent to the heat provided by the sun. The earth's temperature would increase by several tens of degrees Celsius (much more than from currently predicted global warming). The earth would become largely inhospitable. What would increasing energy consumption by 10000x get us? Well, getting everyone in the world to the per capita average level of energy consumption of the United States would increase energy use by a factor of 10x. Increasing it so everyone lives like the richest 1% in the U.S. takes another factor of 5x. If you want to be conservative and leave the earth inhabitable by humans, you can't go much further than that. Of course, if you maintain (or amplify) global inequality, you can do all sorts of crazy things. [Answer] How unlimited is unlimited? If you're serious about energy being unlimited, then converting energy into conversion is on the table: E = mc2. That's 9×1016 Joules per kilogram. At that point, you can have Star Trek replicators (once the science has been worked out), that can create anything you desire. If science works out the inverse – converting matter into energy – then it's only a matter of time until someone is crazy or careless enough to create a hundred kilograms of antimatter, and then the Earth is destroyed. But that will never happen, right? All nine billion people on the planet are completely sane. [Answer] These are the immediate things which come to mind: 1- Free (very cheap) travel 2- Free electricity for all (includes air conditioning and central heating) 3- Production costs of all things reduced by at least 30% 4- Recycling things would be free hence again reducing costs 5- Our knowledge of particle physics would increase tenfold considering that particle accelerators would work at much elevated energy levels 6- Space travel would get a boost In general, much much higher life standard than we have now. [Answer] I am assuming that this cheap energy is non polluting and delivered to its users as electricity. Also that the generating plants are large things and somewhat expensive (so cheap energy not free energy). It would make it possible for everyone to enjoy clean water, enough to eat, a habitation that is not uncomfortably hot or cold. However, although the running of desalination plants, artificial farmland illumination, multistorey farms, heating and air conditioning would become free, capital and people would be needed to build these infrastructures. So don't expect instant utopia. Probably don't expect utopia at all. The planet will still be crowded. If the human population continued to grow exponentially, we would soon again be facing environmental crisis directly caused by overpopulation, rather than indirectly. However there is much evidence that if you give people a western standard of living and access to contraception they adjust the size of their families downwards. So hope exists on this front. Don't confuse cheap "free" nonpolluting energy with universal access to silly wattages in tiny packages. The latter is a disaster like giving everyone hand grenades, or nukes. The former just lets you leave the appliances switched on without facing financial ruin. There will still be wars, terrorists, etc. I don't think not having to pay the electricity bill would make that much difference. Destroy the infrastructures and you can't access the energy. Cue the four horsemen. Not much change at all. Transport. Everyone could afford a car. Probably battery electric, possibly hydrogen made by electrolysis of water. I'd hope that free public transport was developed rather than tens of thousands if miles of ugly space-inefficient motorways. Hydrogen is tricky stuff to handle but might be the future aircraft fuel. Or one could make hydrocarbon fuel by using algae in tanks and "free" electric lightt. We'd be able to clean up the environment without the problem that large energy expenditure incurs large CO2 output which could end up making things globally worse not better. Pollution could be much better managed in this future. ]
[Question] [ Magic works by tricking the universe into thinking something is there when it isn't, or thinking something isn't there when it is. At least, in essence, that's the current theory. As a result, mages can levitate objects, make objects seem heavier, cause fires, make things much colder, and cause buildups of electrical charge where, ordinarily, there wouldn't be - and cause small lightning storms. Of course, there is something there: magic, which has, over the centuries, been observed and studied as much as electromagnetism and gravity. It follows an understandable set of laws which can be used to enhance inherent magical talent and advance technology. In an effort to better understand magic, mages have become scientists like alchemists became chemists. At this point in time, their analogue of Neil DeGrasse Tyson could probably take on Dumbledore, but otherwise their science looks roughly the same as ours (although they have a slight technological edge in some areas). But because magic has been studied in such detail, I'm starting to question whether scientists would even call it "magic." It's an explainable, natural, recurring phenomenon which has been dissected and tested via the scientific method for centuries now. If magic existed, would scientists call it "magic"? Or would they dismiss the word as mere superstition from a less civilized area and insist that it be called something else, with fewer supernatural connotations? Or would "magic" be nothing more than a word that high school students dread to hear, like "chemistry" and "physics"? [Answer] Our current scientific knowledge is the result of our finding replicatable experiments whose consistent results illuminate some aspect of our universe's underlying rules. Your magic involves tricking those underlying rules, so that experimental results may not be consistent. The presence of such tricks would therefore interfere with the process by which our current scientific understanding was formed. But the tricks themselves would also illuminate aspects of how the underlying rules work. If those tricks are consistently affective, experiments would be devised to illuminate exactly how they work. So a different science would exist in your world and magical tricks would be its trusted foundation. A unknown substance wouldn't be characterized by its conductivity, but rather by its conjurability. Not by its low density, but by its lack of predictability. In such a world, magic would not be called "magic". It would be called "science". [Answer] Yes, they would call it magic. Just as we call chemistry chemistry and physics physics. The study of magic would just be another branch of science. The reason magic is something "different" now is because it doesn't work. Any scientific study shows that it doesn't work...so study of it becomes quite futile except for excitable amateurs running around with electronics turned way past any meaningful sensitivity setting and pattern matching for any possible result they can find for a TV show. [Answer] In order to say that something was magic would not only require evidence of magic but a definition of what magic is. If we define magic as anything that would violate the laws of physics then magic is by definition impossible. Even if something that would violate the known laws of physics such as anti gravity, walking through walls, telekinesis, ghosts, and talking to the dead, or free energy were conformed using the scientific method that would not mean that the laws of physics could be violated just our understanding of them and in that case we would have to modify what we know about the laws of physics in order to account for these phenomena. Basically if any so called magic was conformed using the scientific method it would not be magic regardless of how extraordinary. [Answer] I claim that the subset of magic that would be driven predominantly via complex minds would indeed be a distinct field. In this regard, magic would fall within the category of [Strong Emergent Phenomena](https://www.closertotruth.com/series/what-strong-emergence). Also [this](https://en.wikipedia.org/wiki/Emergence#Strong_and_weak_emergence) to understand the philosophical types of emergence. Weak emergence is an extension of the Cartesian principle of science, where some phenomena arise from the complex relationships between simpler, more fundamental phenomena Strong emergence on the other hand, is the notion that there might be phenomena that happen beyond of what can be explained from complexity of fundamental phenomena alone. In many mythologies and narratives, magic is driven by complex minds affecting or influencing phenomena in unexpected ways, Although there are exceptions; [some religions use the concept of inert devices that can recollect or redirect magic energies for specific purposes](https://en.wikipedia.org/wiki/Prayer_wheel). Notably, Terry Pratchett makes use of these narrative devices in the [Thief of Time](https://en.wikipedia.org/wiki/Thief_of_Time) to great amusing effect. [Answer] I've written on this a few times here. See [this post: Can magic be science?](https://worldbuilding.stackexchange.com/questions/22591/can-magic-be-or-directly-work-as-science/22661#22661) for example. In one sense, learning about the universe is "science". That is, the rules of extracting the rules through observation: physics and chemistry emerged from superstition and alchemy. But the rules have a particular nature to them: they are simple relationships based on the most fundamental things. More complex behaviors emerge from lower-level rules. If you are not describing "physics" but real behaviors that we would call magic, it is operating on a teleological level rather than the moat fundamental constituants. How can there be rules defined that operate like primate social behavior, with attributes that match human perception of the macro scale? The nature of the universe would be very different, and I've indexed some posts reflecting on that in the one I linked to. If rules are fuzzy and hard to isolate and reproduce results, understanding them will be more like economics and phycology as opposed to our idea of physics. [Answer] ### Maybe As [Tim B](/users/49) [noted](/a/31934/43697), it depends on whether you retain the meaning of "magic" as "something not explained by science". If it's just a word like "physics", then yes, absolutely they'll use it; it just won't mean anything special. That's probably not what you meant, though, so the key to the answer is already in your question: > > It's an explainable, natural, recurring phenomenon which has been dissected and tested via the scientific method for centuries now. > > > If this is the case, then no, it most certainly isn't "magic". You've exactly described not only a science, but a "hard" science (as opposed to something like economics or politics, which are more of an attempt to apply scientific principles to something which resists such analysis). ### But wait... What if you want to have real "magic"? I'm currently working on a story that has genuine "magic" magic. Even though it's real and clearly demonstrable (in fact, it's a major part of society), it's still "magic" because its workings defy attempts at scientific analysis. "It works, but everything we know about science aside from magic says it shouldn't." It isn't universally available (not everyone can work magic), it's heavily influenced by the mind and intentions of the one using it, and spells in particular (spells are a way of 'baking' a magical effect into an artifact so that anyone can use it) act as if there is some sort of governing intelligence behind them. Of course... simply being demonstrable means that, in some sense, it isn't "magic". The best you can hope for, then, is that it is a third brand of science. "Hard" sciences, which are consistent, rational, and can generally be explained and tested, "soft" sciences which are subject to too many chaotic factors, and "magic" sciences, which are (to some degree, but perhaps not entirely) consistent but which resolutely defy explanation. [Answer] I've said this in another thread: what if we already found magic but called it science instead? Have you ever looked into the crazy world of quantum mechanics? When you dont measure it, it is one thing. When you do measure it it becomes another. Properties at different stages are completely nonsensical from a classical physics point of view. Fire a single particle through a double slit and it will interact with itself to create probable area's where it lands, many of those probable area's arent possible if you measure the particle during flight and that is the most sensible part of quantum mechanics. So yeah, we could have found magic, and we called it science instead. [Answer] I think a definition of “magic” that cuts through some of the difficulties here is to define it as something occurs by Will instead of by Process. “Science” captures the set of phenomena that are repeatable by a known set of physical inputs (move these atoms like so, adjust the voltage, etc). “Magic” captures the set of phenomena where an individual’s will/spirit/soul is an input. So to answer your question, I think the vast majority of what is considered “magic” would get subsumed under the label of “science”. Only if an individual’s Will is involved would the term magic be useful. There is a quote by the author Ted Chiang that captures this approach to magic nicely > > I think that there does exist an useful distinction to be made between magic and science. One way to look at it is in terms of whether a given phenomenon can be mass-produced. If you posit some impossibility in a story, like turning lead into gold, I think it makes sense to ask how many people in the world of the story are able to do this. Is it just a few people or is it something available to everybody? If it's just a handful of special people who can turn lead into gold, that implies different things than a story in which there are giant factories churning out gold from lead, in which gold is so cheap it can be used for fishing weights or radiation shielding. > > > In either case there's the same basic phenomenon, but these two depictions point to different views of the universe. In a story where only a handful of characters are able to turn lead into gold, there's the implication that there's something special about those individuals. The laws of the universe take into account some special property that only certain individuals have. By contrast, if you have a story in which turning lead into gold is an industrial process, something that can be done on a mass scale and can be done cheaply, then you're implying that the laws of the universe apply equally to everybody; they work the same even for machines in unmanned factories. In one case I'd say the phenomenon is magic, while in the other I'd say it's science. > > > Another way to think about these two depictions is to ask whether the universe of the story recognizes the existence of persons. I think magic is an indication that the universe recognizes certain people as individuals, as having special properties as an individual, whereas a story in which turning lead into gold is an industrial process is describing a completely impersonal universe. That type of impersonal universe is how science views the universe; it's how we currently understand our universe to work. The difference between magic and science is at some level a difference between the universe responding to you in a personal way, and the universe being entirely impersonal. > > > [Answer] I think that sceptics would legitimise their scepticism by being passively derogatory of their opposition. Like, they would use words like "tricks on the weak minded" or "mass hysteria" or "gullibility factor" or "mental illness" etc. In this way they can imply that the reason that anyone disagrees with their conclusions is that they are irrational, and therefore should be regarded dismissively. They would not be subject to any kind of peer review because contrary opinions are the result of this so called "magic" phenomenon and therefore must be dismissed. Any scientist who actually "saw" the magic would be out of a job, and no longer able to publish papers. ]
[Question] [ On Earth, tides generally tie to a 12 or 24 hour cycle depending on the location. The exact times and heights are generally based on the shape of the sea, and the positions of the moon and sun. What I'm wondering is if there's a planetary system setup that would give very long cycles - say at least a month - between high and low tides. Additional requirements: 1. The planet needs to be habitable by humans (habitable zone of the star, or otherwise kept warm/cold enough). 2. Tides should be at least as extreme (in terms of height between high/low tides) as on Earth. More extreme is better. 3. The planet should be of roughly the same composition as Earth - no making it out of diamond and then sticking it inside the Roche limit of a gas giant or the like. 4. No magic. Note: It seems like you could just change the period of the moon's orbit to get this, but I believe that would also involve changing the moon's orbit and mass, which would change tides in other ways. So it's not quite as simple as that. [Answer] There are two formulas at play here. Since you want the tides to be similar or more extreme in magnitude than on Earth, we need to consider the tidal force (thanks to celtschk for the correction) between the planet and moon: $$\overrightarrow{a}\_t\rm{(axial)}\approx\pm\hat{r} 2\Delta rG\frac{m}{r^3}$$ Also, since you want to change the tide cycles, we need to consider the orbital period of the planet and moon: $$T=2\pi\sqrt{\frac{a^3}{G(m\_1+m\_2)}}$$ Here, $r$ is the distance between the two objects, and $a$ is the semi-major axis of the orbit. If we assume an approximately circular orbit, $a=r$, so we get $$T=2\pi\frac{r^{3/2}}{\sqrt{G(m\_1+m\_2)}}$$ In order to get a longer tidal cycle, we need to have an orbital period closer to the planet's rotational period, so we need to change the moon to decrease $T$ while keeping $a$ constant (or increasing). For a simple case, let's cut the radius of the orbit in half. In order to keep the force the same, we'll need to divide the moon's mass by 8. What effect does this have on the orbital period? Well, if we assume the moon's mass is relatively negligible (our moon is about 1% of the mass of Earth) we have $$T\_1=2\pi\frac{(\frac12r)^{3/2}}{\sqrt{G(m\_1+\frac18m\_2)}} =2\pi\frac{\frac{1}{\sqrt{8}}r^{3/2}}{\sqrt{G(m\_1+m\_2)}}=\frac{1}{\sqrt{8}}T$$ That means the moon orbits about $2.8$ times faster. If we go with 1/9th the radius and 1/729th of the mass, we get an orbit $27$ times faster, or about $1.1$ days. This gives you a tidal cycle of about $10$ days, as opposed to $30$, but the ratios to get a $1.03$ day orbit aren't as nice. (Edit: it's about 1/9.35 for the radius, and 1/817.4 for the mass.) You can go with a little more mass to increase the magnitude of the tides. Also, while this moon is a lot closer than ours, it is still well outside the Earth's Roche limit. Also, it has a faster orbit but is below escape velocity for that distance. So it won't break apart or go flying off into space. [Answer] I'm sorry that my knowledge of how this would work is a bit limited...but here is a possibility. You can have your day/night cycles however you'd like...but the planet would have to be almost tidally locked to its moon. The mechanics of this dictate that it would only stay that way for so long before the planet and moon became truly tidally locked to each other...but it'd still be a pretty darn long time. In short, if a planet's day and lunar month were almost the same (which, given enough time, would happen to any planet/moon system), then you could have a very slow tidal cycle. The catch here, is that the planet's day would be about the same length as the tidal cycle, which leads to a whole host of problems for any inhabitants of the planet. To have a stable orbit, the distance from the planet, mass of the orbiting bodies, and speed they are moving all must fit together. For a moon to move faster (thus catching up with a planet's rotation speed) and not escape the planet, it must either be more massive, or closer to the surface of the planet. Either of which also increase the strength of the tides, possibly to the point of leaving the planet uninhabitable. The balance to this is to slow the rotation of the planet, lengthening the day, rather than decreasing the lunar month. This would lead to greater extremes in temperature between day and night (just look at the temperature variance between day and night on Earth). So, ultimately, you'd need to play a balancing act of a moon that was massive enough and close enough to effect the tides, and then speed it up or slow down planetary rotation to reach an equilibrium where the lunar month was just a little bit longer than a planetary day. Other than that...the near-synching of the day/lunar month period...there is no way to produce a long-lasting tide cycle. In order to maintain a near-Earth-like day cycle...here would be a good balance: A Super-Earth to increase the gravity well of the planet, a fairly massive moon, orbiting at high speeds, at fairly close proximity to the planet. Unfortunately, this may cause the tidal effects to mess with the landscape as well as the water. I don't currently have the time to crunch numbers to try to come up with a solid set of results...but that's a base to start on. [Answer] How multiple moons would act on the tides: ![enter image description here](https://i.stack.imgur.com/YIASJ.gif) Ignore the frequency and times given here and look at how the waves add up. This is called a beat. The important bit is that the sum can seem like it has a much longer wavelength and thus your moons can get away from being nearly geo-locked when your tides hit the once-a-month mark. Actually, when you're geo locked the tides hit the once-an-infinity mark. But what about those little extremes inside the beat? Instead of this giving you half a month of eb then half a month of flow it's giving half a month of almost nothing going on then half a month of twice daily extreme tide changes. Not exactly the same as what you asked for, but interesting. [Answer] For a simple earth-moon system, the moon would have to be near a geosync orbit - that way the moon's movement across the surface can be whatever you need it to be. Geosync seems rather close for a large moon, but it is still well outside the Roche limit, so I don't see anything preventing it from being reasonably stable as long as the planetary composition is uniform enough to still behave like a point source at that distance. Multiple moons could also work - a bunch of small moons that have little effect on their own, but cause large tides when they all line up in the right way. The actual tide cycle might end up quite complicated, as you would also get smaller tides when only some of the moons are aligned. If the moon was in a highly elliptical orbit, it could spend most of its time too far away to cause tides, but really make things slosh around when it gets close to earth. A month would probably be on the low end here - that would basically amount to stretching the moon's existing orbit, and likely put the closest approach a bit too close. For something more extreme, try a co-orbital planet - no tides at all for centuries, and then anything short of tearing the planet apart. [Answer] Does it have to be the whole planet or perhaps only a localized phenomenon? Imagine a narrow land mass (a bit like Panama) dividing a large ocean and a giant lake (the lake about the size of the Caribean Sea, or perhaps a little smaller). At spring tide the tide runs over the the narrow land mass and into the lake resulting in a large tidal wave at the other edge of the lake when the tide gets there. The duration of the phenomenon will be a couple of days each time. Slowly the extra water will disappear through rivers/evapouration. (Writing this it occurs to me that the narrow land mass would erode too quickly for this to be a phenomenon that occurs over millennia, maybe others can extend this idea). [Answer] Yes, there are a few ways. ## 1. Slow the rotation of the earth The tide is created twice a day as the earth rotates under the moon. The gravitational pull of the moon makes the aquasphere slightly elliptical. To create a longer cycle, slow the rotation of the planet. This will also create a longer day/night cycle. ## 2. More than one moon The tide is a stable waveform with a period of approximately 12 hours. It is created not only by the pull of the moon, but also by the inertia of the aquasphere. If you add a second moon you might potentially create an interference pattern which would flatten the waveform for most of the month, building to a giant tide once a month when the two moons were in phase. ## 3. Elliptical lunar orbit An exaggerated elliptical lunar orbit would bring the moon close to the planet less frequently. The sligshot would create a very high tide once a month or so. Other tides would be much less noticeable. ]
[Question] [ What would happen if a powerful explosive went off in the core of a planet? On Earth, you have several layers of the planet, the crust, the magma, the outer core, and the inner core. Right now, human technology can't really get past the crust. But say an alien civilization came that could get all the way to the inner core. So this alien civilization comes and uses their technology to plant a powerful explosive, say at least as powerful as a [Fusion bomb](https://en.wikipedia.org/wiki/Nuclear_weapon#Fusion_weapons), in the inner core. What would happen? And for a bonus, what would happen if an explosive with three times the power of a fusion bomb went off in the core? [Answer] ## What is the core of the earth like? The core of the earth is a moon sized ball of heavy metal, mostly iron, also gold and other metals. The pressure is so intense that the iron enters a new crystalline phase. It is so dense that even a very large human scale bomb would have little noticeable effect. An extremely large explosion might possibly be able to crack, shatter or damage the crystal structure in some way. ## Function of the earth's core The inner core rotates at a different speed to the rest of the planet. This generates a massive, but relatively weak magnetic field which shields the earth from solar rays by guiding them to the poles, giving us the aurora. Without it, our atmosphere would be ionised by radiation from the sun and gradually stripped away killing everyone. The oceans would alternately freeze and boil as the earth rotated towards the sun. Everything would die. It is possible to conceive of a bomb that might disrupt the earth's geomagnetic field in some way, perhaps switching it off temporarily, or reversing its polarity. ## Geomagnetic Reversal The polarity of the Earth's magnetic field naturally reverses every few eons. This generally takes place over a long period. Some people have associated these reversals with extinction events, and possibly with a temporary cessation of the geomagnetic field. If a reversal could be triggered quickly, this might be a very damaging sudden event. Imagine all the magnetic rocks in the earth going "kachink" at the same instant. There would likely be earthquakes, volcanoes, cracking of the earth's surface, etc. A slow reversal or temporary cessation would lead to damaging electromagnetic radiation reaching the earth's surface causing damage to organisms and eventual destruction of the atmosphere. ## Reference <http://en.wikipedia.org/wiki/Geomagnetic_reversal> [Answer] On the surface the effect would be nothing in either case. We'd probably see a few tremors on seismographs but I'm not even convinced about that. It would depend on how well the shock-wave passes through the planet. The explosion would be very thoroughly contained by the heat and pressure at the core and the shock-waves would have a huge distance to spread out before they reach the surface. The core is a very long way down, and we have a lot of rock (most of it already a seething molten furnace) between the core and the surface. An interesting follow on question though would be to ask how powerful a device would need to be to have an affect on the surface (you would need to define the desired affect). I'm not sure if we have any way to answer that though as we just don't know enough about conditions down there and how the shockwave from an explosion would propagate. [Answer] This is my new favorite question, because now I get to compare two of my favorite explosions side-by-side. Let's assume we're limited to actual nuclear weapons that have been developed, and that we're using the one that will deliver absolutely the most powerful blow to the core of the Earth. Tsar Bomba The [Tsar Bomba](http://en.wikipedia.org/wiki/Tsar_Bomba) is the most powerful and funnest-to-say nuclear bomb ever constructed by humans. When detonated, it delivered 50 Megatons of force, with a blast radius of 4 KM, and 240 Petojouls of energy. But that was only half of the maximum yeild for the bomb, limited to allow the payload delivery plane to escape the blast and for a scout plane to take pictures. If we take those safeties off, we can double all those figures. Krakatoa ...Which is still only one-half of what mother nature can do. In 1883, the volcanic island of [Krakatoa](http://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa) erupted, blowing the entire island into pieces. This explosion had a force of 200 Megatons, four times that of the Tsar Bomba's explosion, and still twice the blast of a theoretical unhinged Tsar (but enough about Russian politics...). Both of these explosions occured essentially at the surface of the Earth, which helped the impact spread throughout the surface considerably. Krakatoa Bomb If we could deliver a Krakatoa bomb to the surface of the Earth's core, what would happen? Well, [this Physics question](https://skeptics.stackexchange.com/questions/5840/impact-of-a-nuclear-bomb-explosion-in-earths-core) (which is a good question, but strangely posted on Skeptics and therefore closed) points out that this type of explosion would be equal to an [8.75 earthquake](http://en.wikipedia.org/wiki/Richter_magnitude_scale). Which sounds frightening, unless you factor in the fact that earthquakes are (believed to be) the result of the constant churning of the mantle beneath the surface of the earth, and that the forces further down will be even stronger than that. So unless your Alien Fusion Bomb manages to be stronger than the Krakatoa explosion, we aren't likely to feel an earth-shattering effect from just one. At worst, we may suffer from a few seismic disturbances, but you'll need to step up your payload considerably to do any real damage. ]
[Question] [ A immortal dictator controls an island with about 1,000,000 people. Apparently, he's super into eugenics and wants the population of the island to be "the ultimate humans". Assume he can control who reproduces (and who does not). He would want to select the "top" `X`% of fertile females and `Y`% of fertile males to produce the next generation. Problems To Consider: * If `X` or `Y` are too small, there will eventually be problems with inbreeding. * If `X` or `Y` are too large, he won't be selecting for the "very best". * I assume that `X` will be much larger than `Y`, but I could be mistaken. Problems Not To Consider: * How the dictator enforces this. * What "top" or "best" means; this is based on his subjective criteria. Clarifications: * 1,000,000 is an arbitrary number and a general solution for any population size would be preferred. * The population of the island should remain the same. * "Fertile" means "can safely reproduce". * If a person is chosen to reproduce, their partners are chosen (semi-)randomly and outside of multiple births, no two children have the same parents. * Since he's immortal, the dictator wants to be able to maintain `X` and `Y` indefinitely. What is the minimum percentage of males and females that can be allowed to reproduce without running into inbreeding problems? [Answer] A woman's birthing career, if she does little else, is about a pregnancy per year for 16 years, from the age of 16 to 32. Beyond 32, you run a risk of greater genetic anomalies, nearly always not good. A male is about the same, even though males are essentially fertile for life; the same thing happens with age; a greater risk of genetic anomalies. But one man can impregnate almost any number of women, even one per day. You don't require a lot of men. From there, presume there are no multiple births or child deaths; each women can produce 16 adults. The replacement value for the population of X is X/16 women breeding. That is about 6.25% of carefully chosen women. Since the proportion of men required is far smaller, we can be more selective with the men. (Nature is too; for example in horse herds nearly all foals have the same father, that impregnates 95% of mares. A few rogue non-alphas manage to impregnate the other 5% of mares.) So say, our breeder males impregnate a woman on average once per week, which is 52 times more often than women get pregnant, so the 6.25% of women require about 1 out of 832 men. So only about 6.37% of the population is breeding; one in 15.7 people. For any decent sized population in-breeding should not be a problem; the odds of people having the same father in a population of 1 million is about 1200 to one (1m/832). (1200 is also the number of breeding males (1m/832), while the number of breeding females is 62,500). It should be relatively easy to ensure every coupling pair has no common parent, grandparent, or great-grandparent. I believe that is the extent of in-breeding you need to worry about. Edit: To preserve the idea of LuizPSR: If artificial insemination is an option, then the dictator can select his ideal couples, gather sperm and eggs to produce his new genetic specimens, and force non-selected women to carry those blastocysts to term and raise the children (to which they have contributed no genetic material). The "ideal" women would never get pregnant. Just harvest an egg per month from them. This could drastically cut the number of women required. The only worry then is management to prevent inbreeding and ensure genetic diversity. Yes, it is a brutal form of slavery, but that is the fictional premise. So, for example, if the dictator deems only 1% of women as breedable, then each of those women must produce 100x more babies than they would have if free. But that is possible, she would have produced 2 in her lifetime, she needs to provide 200 eggs, which she can do in 16 years, 8 months of monthly egg harvesting. Thus from the age of 16 to 32 +8 months. Those would be implanted into two hundred non-breeding females, as the eggs become available, and eventually all the non-breeding females will have two children. [Answer] Your problem is not how many, but how long. Each generation in which you prevent a significant part of your people from breeding removes a proportional chunk of the genetic variability of your population. This is fine for a few generations, especially if your population is diverse to begin with (debatable, on an island) and you pick your breeders with some care for physical and genetic fitness (note that we don't really understand enough of genetics to do this even today). But keep this going for generation after generation, and you will inevitably funnel your people into a genetic bottleneck. Intuitively, your gene pool is decaying exponentially, losing the same % every generation. This is why adding selection is worse than just leaving a 1,000,000 population to breed in isolation. Sources that would increase genetic variation exist, but are much slower, and probably undesirable anyway for an eugenicist. The other point to keep in mind is that this plan would presumably fail, if the goal is to produce "ultimate humans" (however defined). Either the dictator knows much much more about genetics than we do (in which case he'd be better off with a gene editing programme) or he doesn't (which I suspect to be the case, or he wouldn't embark in a plan like this) and therefore, like us, doesn't actually even know what to select for. You would at best produce a genetically fragile population with some unnaturally over-represented superficial trait. Eugenics, beside the moral repugnance, is just a stupid strategy. [Answer] This is mentioned by LuizPSR in a comment and I decided to make it full answer. If the setting is about same technology as ours, instead of impregnating chosen women, you collect eggs, fertilize and implant into foster mothers. This allows women to produce slightly less than one offspring per month. With this you can reduce the breeding population (down to maybe 5k) close to a level where only problem is to avoid in breeding. With this method every couple will receive their own children to look after if your villan desires, reducing uprising chances and not birthing 10+ children will allow breeding population to live healthy lives. [Answer] A few assumptions: 1). gender ratio close to 50:50. 2). a female can "safely" bear 4 children (theoretically allowing the population to double every generation - classic exponential growth). 3). reproduction via biological methods rather than IVF or other technological approaches. Parameters: 1). As few people as possible should reproduce. 2). The initial population of 1x10^6 should be maintained. Therefore at least half the females need to reproduce, just to replace the existing population. As other answers have pointed out, the number of males required is smaller. How much smaller depends on how your dictator is running the breeding program. The large number of females means inbreeding is less of an issue, although there are risks of gender linked issues in the males due to the smaller number of Y chromosomes. However, if the tech level is up to genetic testing then these could be screened for. At that point it would also be easy to tell when females were close to ovulation giving increased chances of success at achieving pregnancy over random copulation. How dehumanised do you want the breeding program to be? In this scenario it would be possible for an eligible ovulating female to be required to report to a stud facility for copulation. Exactly how many males you need in this scenario depends on a whole bunch of other assumptions, but between one and five thousand seems a reasonable number. If we assume that genetic screening/fertility detection is not available or that the dictator is not literally monstrous enough to breed people like cattle, the perhaps a hareem system may work. Selected males are given high status, and eligible females are at least free to select among the males looking to add to their households. At this point you are probably looking at around 25,000 - 50,000 reproducing males. More than sufficient to avoid any problems with inbreeding, although you have other huge problems with societal stability. (Namely half a million males competing for the affections of only a quarter of a million females). [Answer] (I took a qualitative approach, this percentage you ask for could be anywhere from "small minority" to "relevant part of the population", depending on the means your dictator has to control the process. You do have a dictator, that comes in handy.. suppose the population is obedient..) ## Prevent inbreeding ? Eugenics ? depends on coordination "Fertile" means "can safely reproduce" you say, that does not hold and will not help your dictator's eugenics project. My intuition says it would depend on technological level, which is not specified. Don't hesitate to fillin the dots and specify technology, I'll focus below answer, With high tech medical devices, it won't be a problem at all. You start out with a million people, that gives sufficient diversity to start with. Just sequence all of your population's genomes and regulate such that you get 1) max distance between the genomes that mate and 2) mix certain properties required by the eugenics project. This procedure does not need family checkups, the minimal allowed genome distance can be set to a certain value, by law. That minimal genome distance will determine the percentage allowed to have kids. With your average 19th century doctor present, and a population that is obedient, you could regulate pregnancies, by letting the doctor assert family relations and health risk. You could "breed" a very healthy population, if you have a registration of family relations in place, which could be done in the 19th century. But I doubt your dictator would have the patience to wait for the result. And very few members of the population can take part. Your doctor travel around on the island, arranging the marriages across villages and using local municipality archives to check things. If that check is accurate, no inbreeding will occur. In a medieval society, starting out with one million people, any attempt in eugenics would become a mess, whatever your dictator tries to regulate. He could try.. say, a very limited, selected part of the population would be isolated in "breeding houses". Issue is, you can't select these people safely, because there is no accurate family registration. Probably, cultural preferences would cause inbreeding, especially in these breeding houses. A 1M population may survive - many modern societes started with far less - but the eugenics project will fail. In order to prevent inbreeding, the dictator could set a rule by law: inhabitants of the same village can't mate. This would circumvent inbreeding, but only statistically. It would occur. ]
[Question] [ Could a plant, with the right adaptations, have the right speed and strength to capture an unprepared human without harming them? The plants would be bound by real rules of biology, and couldn't use muscles or other traits exclusive to groups other than plants. The plant would also be capturing the humans with a vine-like structure that coils around the victim [Answer] You might consider [Drosera capensis](https://en.wikipedia.org/wiki/Drosera_capensis), also known as Cape sundew. This plant has long and thin leaves, covered with small sticky tentacles. The leaves curl up to entrap anything that gets stuck to them. [![Sundew leaf wrapped around a fly.](https://i.stack.imgur.com/1QAcr.jpg)](https://i.stack.imgur.com/1QAcr.jpg) A larger version could have a burr-like surface to further entangle the human's clothing, delaying extraction and giving time for the leaves to curl. As someone that recently hiked through some brush, I can testify that it is easy to get trapped in vines, even without any sticky mechanism. It was easy enough to get out again, but it took significant time, and time is what is needed here. The plant wouldn't even need to be huge, using a single leaf to make the capture. A struggling human could be trapped by multiple leaves, each of which need be only large enough to wrap around an arm or leg. Once the hands are immobilized, it's game over. See: [Best of Sundew Timelapses Compilation - YouTube](https://www.youtube.com/watch?v=0vzc-t1d3Io&ab_channel=CarnivorousCorner) [Answer] # Trap and Poison: If you want to catch something the size and skill of a human, then NOT harm them you've got logic issues, since some benefit needs to come to a plant. You'll need to explain why a plant would have a system for capturing humans unharmed. But once you get past that, I'd suggest a few mechanisms that work well by themselves or in combination. First, your plant produces a fruit that is a powerful tranquilizer - possibly a pleasurable or addictive one. Now, depending on how you define capture and the timeframe over which you want to capture them, they are captured short-term (knocked out) or long-term (they wake up and REALLY want more of the fruit, despite it knocking them out).the person spends all their time passed out under the tree. The justification here is that perhaps the tranquilizer is fatal to other species that die and decompose under the plant, OR that the tranquilized animal is killed by predators (who are possibly ALSO tranquilized and killed by yet other predators, leading to a La Brea-type situation with lots of decaying animals. * If you want a vine-type mechanism, then the vine is coated in the tranquilizer, and the tranquilizer induces a craving to wrap the vines around themselves or cuddle up into the vines. The person is then self-capturing! * Another variation on this theme is that the plant relies on monkeys to carry pollen from tree to tree, and humans are close enough to monkeys to be susceptible to the tree's lure for the monkeys. The monkeys eat fruit from one plant, then are compelled to look for more in another tree. The tree protects it's addictive fruit inside a net of vines to keep other less driven animals out (and the monkeys know how to get in and out). Humans, however, force their way frantically into the net to get the fruit (once they have tasted it) and are trapped. This still works for the plant - the human carefully gets fruit from plant A, along with pollen, is instantly addicted, and seeks out tree B where they get more fruit, deposit pollen, and become hopelessly trapped. Another effective way a plant could capture a human-sized animal is if the root growth created a shaft down into the ground or into a grown structure that functions as a pit. When big enough, a thin covering over the "pit" is thinned enough to allow a human to be lured to the pit (with fruit, fake treasure, or whatever) and the funnel-shaped pit then wedges the human into an ever-narrowing hole. Directional spikes wedge the human in so they can't extract themselves. * Ideally, the pit is lined with drugged thorns so the human that falls down it is tranquilized to fall into a deep slumber and not resist. Then the plant can hold the person there indefinitely for whatever nefarious reason an author can have (since plants obviously don't think... Or do they?) If it has to be vines, then the pit is lined with vines that swell with fluids when touched. The vines swell and pressure-tighten, with more swelling the more the human resists. * A spring-loaded (the spring being a branch) loop snare could be grown, with a lowering branch trailing a network of roots to hold it in place, then an appropriate trigger causing the loop snare to pull tight around a human's limb. The tranquilizer then numbs the person unconscious, allowing them to be held indefinitely. [![tree loop snare](https://i.stack.imgur.com/1cEq4.png)](https://i.stack.imgur.com/1cEq4.png) [![grown pit trap](https://i.stack.imgur.com/I6w00.jpg)](https://i.stack.imgur.com/I6w00.jpg) [Answer] > > The plants would be bound by real rules of biology, and couldn't use muscles or other traits exclusive to groups other than plants. > > > Direct attack is less likely at human size and reaction speed, but you can use the idea of traps. * I remember I saw something like this in that documentary... what's it name?... something like Harry Potter - except they stepped onto a tangle of vines or roots that shifted beneath them. I can't remember if that happened before or after they played some kind of weird chess. * with "gravity assist" the things can go quite fast - like a mass of vines clinging up from the lower branches of the trees by tendrils, tendrils that give way when the prey is well under and so bury the pray in the tangle of vines dropping from above. * then [World's Biggest Carnivorous Plant Catches Whole Sheep!](https://www.youtube.com/watch?v=RuzLXxbGc4c) - (well, not quite, it's a sheep that got its wool tangled in brumbles. But a plant doing this way will have chances at the nitrogen locked into those unfortunate proteins). You can use the idea having a plant reorient its thorns (or spawning then over minutes) to make the escape impossible for any prey that got far enough inside of what looked like an innocuous bush. Once the prey is immobilized, vine coiling and the other horrors can take their natural course at leisure. Note the first two potentially match the requirement of "capture a human without harming them" [Answer] * Possibly stretching the definition of capture a bit here, but maybe the plant has absolutely no interest in capturing humans, it just happens to do so, by constraining them to be within a certain radius. The plant produces a toxin that knocks out some endocrinal capability of the humans, and at the same time produces a substance that is metabolized into a working analogue of the, now missing, endocrinally produced substance. The humans will have to stay near the plant (the substance breaks down easily, and has to be ingested from living plant tissue), or they die. Depending on the substance in question, this might be something that is needed every hour, or once a month, thus giving a wide range of radii to choose from. - If the answer needs vines, the human might need to wrap themselves in living vines to take up the vital substance transdermally. * A plant may have evolved to quickly cover and absorb carcasses, masking the smell, deterring scavengers, perhaps working in concert with a fungus? The plant would grow by spreading their roots, being visible topside only by a few blades of grasslike leaves. As soon as carrion is detected by the leaves, the plant digs into its potato-like subterranean stores and kicks into overdrive, covering the carrion in vines and thistles, releasing substances to help the fungus grow (the fungus will help break down the carrion for ease of uptake). The vines harden quickly, effectively encasing the carrion in a cage (So no big scavengers can rob the plant of its prize). All the tasty nutrients get distributed and stored in the root network. Now, if a blind-drunk human should happen to sleep off their intoxication, they might find themselves in a pickle (literally) the next day. Their immune system will fight the fungus, resulting in nothing more than a rash and a cough, but the vines will lock them in place regardless. [Answer] Very strong vines with an exceptionally sticky adhesive could work. Something similar to [sun dew plants](https://www.igra-world.com/types-of-carnivorous-plants/). For some reason I am reminded of [The Day of the Triffids](https://en.wikipedia.org/wiki/The_Day_of_the_Triffids) . [Answer] How "unharmed" do you want? I'm going for "alive". Thorns. Brambles are extremely dense, and at the right stage in their growth very strong. As anyone who has gone blackberrying can attest, the thorns are also lethally sharp and can feel strong enough to pull your skin off. A bush can immobilise a grown sheep when the wool gets tangled, leading this farmer to theorise that they are actually carnivorous and fertilising themselves with decaying sheep: <https://www.youtube.com/watch?v=RuzLXxbGc4c> So, a large tough dense bramble, equipped with some kind of Venus Fly Trap style motion trigger to close the branches; the more you struggle the tighter they close. They are tough to break anyway, your motion would be restricted, and every move you make would be extremely painful, but would probably not kill you. EDIT: Thinking on this a bit more, the trigger shoots could be away from the thorny branches, on suckers that spread over the ground. Pushing through a dense forest, your hero finds a sort of tunnel where the going is a bit easier. As he walks on through it, he fails to notice the surrounding undergrowth closing in, until SHOOMP! like a Venus Fly Trap, it all closes up. This behaviour could evolve quite nicely over the normal millions of years as a means of catching any large animal; however, with humans' greater intelligence, very few of them are then digested. ]
[Question] [ The sub would be about the size of: * the [Sōryū class](https://en.wikipedia.org/wiki/S%C5%8Dry%C5%AB-class_submarine), which displaces 4200 tonnes (implying about 4200m³ volume) and has a 6000kW propulsion system * the [Oyashio class](https://en.wikipedia.org/wiki/Oyashio-class_submarine), which displaces 4000 tonnes (implying about 4000m³ volume) and has a 5780kW propulsion system * On the smaller side: [Collins Class](https://en.wikipedia.org/wiki/Collins-class_submarine#Propulsion), 3407 tonnes displaced, 4200kW Nuclear tech is not available in this world. They could fuel up on hydrogen from bases, and I might go that route if the answer to this is a hard no, but I would prefer to keep them autonomous. Even this anti-hydrogen-economy article concedes that submarines might be a good niche application for hydrogen: <https://phys.org/news/2006-12-hydrogen-economy-doesnt.html> The question is: can such a sub harvest enough energy from the currents, chemistry, and thermal gradients of the sea around it to run?? ## Reduce power demand Of the above, Sōryū demands 1.428kW/tonne, Oyashio 1.445kW/tonne, Collins 1.23kW/tonne. Note that the bigger they are, the more energy they use proportionally. Is this an absolute law? Something to do with drag, or some square-cube law? Are smaller subs always gonna be more efficient? (If so I may make all the subs in my world smaller.) Or is it just because bigger subs are fancier and have more gizmos? This trend continues in a more pronounced way if we consider really small subs: the [DSRV-1 Mystic](https://en.wikipedia.org/wiki/DSRV-1_Mystic) displaces 37 tonnes with 11.2 kW for a score of 0.3027kW/tonne, and [this one](https://en.wikipedia.org/wiki/Advanced_SEAL_Delivery_System) 61 tonnes with 50 kW for a score of 1.02kW/tonne Can the efficiencies of large subs be brought down to something like 0.3027kW/tonne? Because that would be amazing. Or is it impossible? What's the physics here? It does seem that with aircraft size is bad for efficiency: <https://web.archive.org/web/20180302044700/https://theicct.org/blog/staff/size-matters-for-aircraft-fuel-efficiency> PS: I see now that the DSRV-1 Mystic, as well as using about a-fifth the energy, achieves about a-fifth the top speed, so maybe speed rather than size is the issue. PPS: There's some debate over whether pump-jets are more efficient than propellers (all the subs detailed here use propellers). Here's [an article](https://www.aspistrategist.org.au/pumpjet-future-submarine-not-fast-slow/) on the side of that debate against pump-jets, but it does seem to accept that they'd be better at high speeds. (It also says "the square law for drag means that the energy required for propulsion becomes extremely small at very low speeds", which is good news for this thread.) Certainly the drag is proportional to the square of the speed, so halving the speed means only one-quarter as much drag, and drag is a large part of energy consumption though not all. PPPS: Some comments on increasing efficiency by those guys who got defeated by a flock of emus – <https://apps.dtic.mil/sti/pdfs/ADA428039.pdf> – including the interesting proposal of coating the surface with some sort of polymer to make the flow laminar rather than turbulent on the first few meters of the nose. ## Generating from ocean currents Let's say we don't get the efficiency way down, and our heroes need 6000kW to go. Energy can be harvested from ocean currents. This can be done with turbines, but this tech trumps all - <https://minesto.com/our-technology> - because it claims "Small in size and lightweight. Up to 15 times less per MW than competing technologies." Its compact size makes it perfect for our purposes of a generator the sub can carry. This is credible tech, with government partners, not some scammy website, and it is something like an underwater kite carrying turbines. Could this tech be scaled up to 6000kW? I think it would weigh 70 tonnes then (3MW version weighs 35 tonnes, the 250kW version, one-twelfth the capacity, weighs 3 tonnes, so I guess the weight scales up proportionately with the capacity?) What sort of wingspan would be needed? I see no reason not to make the wings foldable/collapsible. ## Other power sources Anærobic digestion of the crew's waste? Assume 23 submariners; how many watts could be generated? Electrically-active microbes in the sea - <https://tos.org/oceanography/assets/docs/25-1_girguis.pdf> - how much could be generated here? OTEC - <https://www.nrel.gov/docs/legosti/old/254.pdf> envisions a unit generating 32kW or 50% more with advanced materials. The dimensions aren't given, but the figure on page 19 shows it about six feet tall, but I don't think the weight is mentioned. How would this scale up? What size OTEC unit would the sub need to deploy to approach 6MW? ## Bioenergy Several people have brought up that fish, whales, dolphins do what I'm talking about: swim around on ocean energy by using bio-energy. Whales and dolphins do this while also supporting a warm-blooded metabolism. Technology can often do things much more efficiently than biology, so could we ingest biochemicals from the water, digest them more efficiently than an animal, and use them for an efficient propeller? [Answer] # Almost Certainly Not 6 MW is a lot of power, and all of the proposed mechanisms can only sip at available power. (Or wouldn't work at all.) # Efficiency As with anything that moves through a medium, most efficiency gains are realized by aero or aqua-dynamics. So a knife-nosed submarine would see more efficient movement forwards, but would have enormous power demands when turning. The reason that small subs have high efficiency is because their cross-section (and the amount of water they have to shove out of their way) is small regardless of other considerations. Realizing small-sub efficiencies with a large sub is physically impossible. # Current Generation As with all turbine generation, tidal or current generation depends on resistance. The currents want to sweep through an area, the turbines block the currents from doing so until some of their power pushes the turbines around. In the case of Minesto's "kite" generator, the "kite" is anchored to the sea floor and whips around in a figure-eight in response to the currents, generating more power than a normally-oriented tidal or flow turbine. But the anchoring is key. Without the anchor holding the turbine in place, it would simply move with the currents - as would your submarine. Current and tidal generation cannot work with a non-anchored turbine. Unless your submarine anchors in place and charges batteries, it's not going to get anything from that. # Waste Processing Quite aside from the fact that the facilities required to process waste into energy tend to be large and non-portable, you'd need an entirely separate generative system that burned the resultant fuel. It's hard to imagine the poop of 23 submariners making more sense than just burning alcohol. # Biological Fuel Cells Ocean microbes still need food. While a galvanic current can be produced by certain microbes around hydrothermal vents, you'd need to provide the chemical and environmental needs of the microbes - again, it's almost impossible to imagine this as being any more efficient than just burning a fuel directly. # OTEC As with any thermal gradient generation, the gradient is very important. The paper you linked assumed a 20C gradient, which is achieved by having your warm water intake pipe at the surface of the ocean, and your cold water intake pipe [about 3 km down](https://oceanservice.noaa.gov/facts/thermocline.html). Not portable. Not feasible. Edit: (Additionally, the linked paper also makes clear what would be required to scale up their proposed model. About two thousand tonnes of copper-nickel alloy, 500 tonnes of pure copper, and 600 tonnes of thermoelectric material - though that last could be improved by modern thermoelectrics, this is just the generator, not the pumps or pipes.) So no. None of these proposed methods could realistically power a submarine, let alone a nuclear-scale submarine. [Answer] ## What is a sub's role? Engineering anything involves maximizing strengths whilst minimizing weaknesses within a specific framework of constraints. Unfortunately, it seems the baby might have been lost with the bathwater when focusing specifically on size and power whilst ignoring (or at least understating) questions of mission-lifetime, surge-demand, and reliability. A submarine's role isn't simply to be "The sneakiest boat in a Navy!" (for varying criteria for "sneaky")... some stupid-simple inflatable rubber dingy full of relevant personnel can "sneak" a hell of a lot closer to any port-of-interest than any modern nuclear sub can do. Determining the size/power needs of your sub won't simply depend on the size/power needs of current subs... it will depend on the landscape of possibilities that your no-nuclear-powered-subs-world represents. ## What role do nuclear-powered submarines (currently) fill? Currently, most nuclear subs seem to be focused on a mission of providing minimally-traceable launch platforms for fast-attack nuclear missiles. Therefore, our current timeline relies on both the existence of nuclear-energy and nuclear-bombs. However, (despite nuclear-power being a reality in this timeline) not all modern subs are nuclear-powered. Why? Because not all nations want/need first-strike nuclear capability. This means that, for many mid-sized militaries having subs is less about long-term force-projection and more about short-logistics strategic defense... and under such a design constraint going small and diesel-electric is perfectly capable of (if not ideal for) getting the job done. ## What role do your subs fill? If nuclear-power is off-the-table, is M.A.D. force-projection with nuclear-bombs also off-the-table? Do your subs exist as launch-platforms, or more as battleship-killers and recon? If your subs mostly operate in-territory... then off-base recharge may simply be irrelevant; refuelling with diesel\* or hydrogen may simply be best based on the assumed-logistical-capability and mission-selection for subs in your world's near-term future. \* (Consider that, although for aircraft MJ/kg is often king, in seacraft MJ/m3 may be just as likely - if not more-so - to be a driving economical factor.) If your subs mostly operate ex-territory... then what role do your subs serve where parking-to-recharge is absolutely worth the risk of the wait? Any "ocean-energy" technology is basically relying on the economics of remote-generation offsetting the costs of either long down-times or long-term deployments. Either way, you're relying on a never-be-seen-in-the-first-place kind of sneakiness at the cost of losing get-outta-dodge energy-reserves-for-running capacity. So, you're basically pidgeon-holing these subs into mostly recon or infiltration/exfiltration kinds of slow long-term missions. [Answer] On the energy content of human waste The amount of energy remain in the gently used food varies widely based on the person and type of food. But, the highest figures I found during my searches was that about 25% of the original calories passed through undigested in the case of some kinds of nuts - the overall average being considerably lower in people with healthy digestion. So, lets consider a Collins class sub with a compliment of 42 crew. Lets assume 2500 kCal per day / per person intake, with a unrealistically high yield of 25% calories in the waste stream. 2500 kCal \* 42 \* 0.25 = 52,500 kCal = 219.66MJ So over a period of 86,400 secs per day - your total poo will yield continuous power of 2.19E8 / 86,400 = 25.35 watts (not considering conversion losses). Clearly not enough to be useful for powering the sub. How about harvesting plankton / krill? We have the example of whales that survive and propel themselves (frequently underwater) based on the energy they derive from feeding in the ocean. Whales also share size and speed characteristics that are similar to some submarine usages. Developing systems to harvest the available food, convert it into useful energy, and dispose of waste will be complicated, but certainly theoretically possible knowing that whales do it. The engineering challenges in creating a useful harvesting submarine would be severe. You would also need to harvest - filtering large amount of seawater, etc. essentially at the surface of the water - deep water food concentrations are much lower. Even the largest whale is smaller than common submarines - even the most common Nazi u-boat was over twice as long. But the [Electro-boat type XXIII](https://en.wikipedia.org/wiki/Type_XXIII_submarine) coastal sub was about the same length. Note that this sub was so small it was limited 2 torpedo tubes that could not even be loaded internally. jDunlop already provided some detail on the limitations of the other proposed methods. [Answer] ## No, no non nuclear method can generate useful levels of power. Ocean currents require you to be affixed in a location and have extensive support technology requirements that weigh a lot. Unless you want your submarine affixed to the ground floating in a hoop, the submarine won't generate useful powers. Submarines are required to move around, often in locations that are not ideal for power generation. [![enter image description here](https://i.stack.imgur.com/b55k2.jpg)](https://i.stack.imgur.com/b55k2.jpg) They can't just float around in a figure 8 pattern near the coast tethered to support equipment. ## Hunting is also a slow power generation method Blue whales just eat [6 giga joules of food per day](https://answersdrive.com/how-many-calories-does-a-whale-need-each-day-243393). That's enough for about a 1000 seconds of power, or 20 minutes. Unless you are notably better at hunting than blue whales, you're not gonna get enough food. They hunt for the optimal food source in the ocean, on the surface with lots of sunlight. Your methods aren't gonna do better. ## Thermoelectric power generation isn't a reliable power source for moving ships. You need a few hundred tons of pipes going down deep into the ocean. Those pipes could hit things, will weigh a huge amount, could break, and could have lots of issues. The mass would be massively more than you can carry. ## What about bursts of activity? You could have a sub that could hunt for food like a whale. They're not gonna sustain 6 megawatts, or anything close to that, but just by floating around and using passive sonar to feed, they can probably slowly eat quite a lot. They can build up large reserves of fat, or hydrogen fuel cells, for bursts of activity in emergency, or to top up existing power. They wouldn't be as mobile as a normal submarine, or as powerful, but they could extend their on board supplies for a while by hunting. When a threat called they could burn their fat or hydrogen reserves for bursts of activity. [Answer] # [The New Age of Sails](https://www.nytimes.com/2021/06/24/magazine/cargo-ships-emissions.html): Ships circumnavigated the globe using the power of the sea centuries before modern vessels, and they didn't even need hydrogen fuel. They used one of the oldest power sources on your list. They used sails. Today, modern ships are returning to their roots and developing sail technology to off-set the very power concerns you have. Deliver the ship to where it needs to go without external inputs at the lowest cost possible. By trying to use all these power sources to generate electricity, you bind yourself to engines, to mass, to sitting still for long periods. If you're going to slow down the trip anyway, why not open up a deployable sail and just drift along? Many innovative designs are coming out to allow easily deployable sails that don't take up large amounts of deck space. these same designs can be stowed when the ship needs to submerge. similar set-ups can harvest some of this wind energy for electricity that can then be used to charge batteries or possibly even generate hydrogen to refill the fuel tanks you'll still need to submerge. I could even see designs where you have lighter-than-air sails filled with that same hydrogen fuel you're making. pump out and pressurize the hydrogen to submerge, folding up the sails. So you'd use wind to generate hydrogen AND keep the sails inflated, only pressurizing it when you had excess. Thus the ship sails, makes it's own fuel for later, and your submarine may even just look like a low-tech vessel sailing across the ocean anonymously. If your world still uses wind power to transport goods cheaply due to fuel constraints, it's the other end of stealth - hide in plain sight. For much of the history of submarines, they traveled on the surface because it took less fuel and solved the problem of air. Hulls were optimized for surface travel, only diving when needed (in your case, whenever the plot calls for it). Nuclear power pushed the subs off the surface because they no longer had to be there. This is simply a return to the world before nuclear power. Goods were still being shipped via wind power till around the end of WWII. For a really autonomous submarine, flirt with being a sailing ship. [![Sails for modern ships](https://i.stack.imgur.com/SfNer.jpg)](https://i.stack.imgur.com/SfNer.jpg) [Answer] ## For Endurance, Solar Might Work This is very dependent on water conditions, but light can penetrate dozens of feet of water. If you're at periscope depth, the hull is only a few feet below the waterline. If required, you could potentially extend some kind of semi-submerged or floating array - it would be easy to see in satellite imagery, but hard to pick up on radar since its so low to the water. ## Submarines are most useful at PD Periscope Depth is the place where a submarine can employ the most tools - the 'scope, cruise missiles, and comms masts are all denied to a submarine that is deep. So spending most of your time at PD makes good sense anyway. ## You can't be Fast Nuke boats are the only real option for going fast at depth - nothing else has the energy density to keep up. Even very modern diesel boats move slowly to conserve battery charge. The Solar Sub is basically created a manned mine, which limps out to a given spot, floats there, and releases a barrage of torpedoes against any interlopers. This is more or less what diesel boats are today. The solar sub is less steathy, but has the ability to crawl further from its supply lines. [Answer] ## It Could Easily Power Itself as Long as it is Staying Still The niche of Nuclear powered ships is long term deployment. But being deployed for a long time does not have to mean moving around a lot. LetEpsilonBeLessThanZero's answer sort of touches on this idea, but missing the mark on recognizing the usefulness of a stationary sub. The subs you are referencing only need those massive power outputs when moving, but when just sitting on a sea shelf, you significantly reduce your power needs to little more than passive surveillance equipment and life support which can all be met by even a relatively tiny tidal generator. So, in this respect you could use a normal diesel engine to get where you are going, then deploy some kind of stealth netting to make your sub look like its part of the sea floor to enemy sensors, then use tidal energy for months on end as you silently await orders. While nuclear cruise missiles are the big one we use behind enemy line subs for today, it's not the only option your civilization could have for needing something like this. Your sub could be armed with biological weapons, dirty bombs, EM warfare systems, sea-mines, surveillance equipment, drone swarms, or something totally made up. It does not matter what is is as long as you can imagine something worth keeping deployed near an enemy shore for long periods of time. [Answer] Ok worldbuilders, can we have a chat about METHANOL There's certainly methanol in seawater and this paper – Mincer, T. J., & Aicher, A. C. (2016). Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton. PLOS ONE, 11(3), e0150820. doi:10.1371/journal.pone.0150820 – says the following: > > Stan-dards were prepared using analytical grade methanol (99% purity, Sigma-Aldrich, St. LouisMO, USA) in sparged natural seawater (bubbled through a sparging stone with nitrogen at 50mL/minute,5 hours at room temperature). Methanol standards were included in every run,in triplicate technical replicates, with typical concentrations in the range of 0.240–24 micromolar (μM), a typical calibration curve is represented in S1 Fig. > > > Now is that saying there are 0.240–24 micromolar of methanol in seawater or not? To cut to the chase: what IS the concentration of methanol in seawater? You wouldn't need to combust it (using oxygen you don't have) to generate energy; you could use one of these: <https://en.wikipedia.org/wiki/Direct_methanol_fuel_cell> <https://www.sciencedirect.com/topics/engineering/air-independent-propulsion> mentions methanol fuel cells as a possible form of air-independent propulsion for submarines. [Answer] So your criteria are [1] autonomous, and [2] non-nuclear. I think there's a way to fulfill [1] if you compromise on [2] There are 3.3 micrograms of Uranium in a liter of seawater (<http://large.stanford.edu/courses/2017/ph241/jones-j2/docs/epjn150059.pdf>) Therefore there are 3.3 milligrams per cubic meter That's 0.0000033 kilograms per cubic meter Uranium contains 22,394,000 kWh/kg 0.0000033 × 22,394,000 = 739.002, the number of kilowatt-hours of Uranium energy in a cubic meter of seawater. You'd need to process 81.2m³ per hour to get 6000kW worth of Uranium (or twice that at 50% extraction efficacy, ten times that at 10%, etc.) Metal-organic frameworks (MOFs) could be used in a futuristic setting to extract the uranium from the seawater. Not sure how uranium refinement/enrichment fits in to this picture. [Answer] # Yes, they're called thermal gliders Gliders work by yo-yo-ing up and down by emptying/filling the ballast tanks, and using wings to direct the up-down motion into forward motion. That's very energy-efficient because the pump is only on for maybe one minute per hour. Small robotic gliders have gone on for months and months on battery power, so yes low-energy submarines are possible using this principle. [![enter image description here](https://i.stack.imgur.com/lgXD6.gif)](https://i.stack.imgur.com/lgXD6.gif) An even lower-energy variation, more close to the ocean-energy-harvesting concept you're asking about, is the thermal glider. This exploits the predictable temperature-difference between the top and bottom of the yo-yo to power the movement. When it's in higher, warmer waters, a working fluid expands, compressing an internal bladder that contracts an external bladder, causing the glider to sink. This sinking acts on the wings, driving the craft forward. In lower, colder water, the opposite happens. Jenkins, S. A., & D’Spain, G. (2016). Autonomous Underwater Gliders. Springer Handbook of Ocean Engineering, 301–322. doi:10.1007/978-3-319-16649-0\_12 says the thermal glider "gives the glider the ability of renewing its onboard energy stores by harvesting environmental energy from the heat reservoir of the ocean, specifically from the temperature differences of the cold deep water and the warmer surface water (available in 80% of the world’s oceans). Ranges of 30 000 to 40 000 km, circumnavigating the world, then become conceivable." [This study](https://escholarship.org/uc/item/1c28t6bb) talks about the possibility of large (submarine sized) thermal gliders. Page 193: "Figure 10.15 suggests that the thermal glider approaches a state of perpetual motion with increasing size. For example NTE~10 (net transport efficiency) for V~30,000 liters, wherein 99.9999% of total energy consumption is hotel loads. The larger thermal gliders are able to drive the buoyancy engine almost entirely from the thermal energy that is recovered." (If 99.9999% of total energy consumption is hotel loads, and 0.0001% is driving the engine, then that could be gotten from the sources you mentioned.) You were on the right track with OTEC: it is about exploiting the temperature difference between higher and lower water. But there's no need for pipes; you have a moving vehicle that moves the water between the two levels. ]
[Question] [ I’ve watched a lot of people place their ideas here and receive feedback, so I’ve decided to take a try. You see, I’m planning on writing a story focusing on the relationship between humans and Kaiju through a parody of a Japanese high school setting. I’ve already got the Kaiju in my story mostly planned out. For one thing, the reason they exist is explained by the fact that they hail from an alternate dimension, where the laws of physics are very different from our own. They are also sapient, being just as intelligent as humans, and have their own society. The thing is, they very significantly in size, being about 10 m at the smallest, and 1 km at the largest. My question is, could a society with individuals of vastly different sizes work? [Answer] A better and more grounded question is not with mountain-sized animals but by comparing a society of humans and small +/-18mm long creatures, which if I didnt mess up my unit conversion again would be 1/100th the size. Lets say intelligent scorpions and fairies live with us. Smart though these creatures would be, would humans really pay enough attention all the time to keep these creatures safe? Just stepping wrong could kill one. You'd have to set up the entire society with safe zones and forced segregation to keep them safe. Such forced segregation wouldnt be much of a society, with very limited area's of contact. At its core you would have dozens of societies living close to each other based on size and potential extra abilities (flight vs walking for example) but with very little contact inbetween, if only for the safety of the smaller one's. Theres also a huge difference in economical and social capabilities. A human needs much more space in housing and transport than a small creature, but can handle larger things. Still any desk-job for an 18mm size scorpion would earn him the same as a human, but the scorion requires less light, space and infrastructure to function. The desk of one human would already be an entire office building for the tiny creatures. For other jobs like farming a human would be better... as long as automation doesnt factor in. A tractor with a miniature cabin could just as easily be steered by a small creature as a large one. Could such a society exist? Yes, but it would be a very skewed one. The small creatures would dominate the economical market, requiring less food, space and energy for the same living and workconditions. The larger creatures would be too uneconomical for employers to build offices for and forced into manual labor that is harder to automate by the smaller population. The larger one's would hate how much money they have to pay to just stay alive while the smaller one's will have plenty of stories about accidents where the giants killed smaller one's in one way or another. Hatred and violence would be a key component of such a society, with sects on both sides using poison or brute force to sometimes kill the others. [Answer] OK. The simple answer is, in principle, why not? However, the size differential between the smallest and the biggest Kaiju is a factor of one hundred. Enough to cause a sharp intake of breath. Societies by themselves aren't simple things. They are complex and multi-factorial. Complex and multi-factorial systems can accommodate a lot of variability. For example, the Kaiju might organize themselves geographically in groupings by size. This could add a whole new meaning to the commonplace phrase "the big end of town". Also, different Kaiju might different in other ways too. Some might fly, others breath out radioactive fire, tunnel at high speed through ground, live underwater or inside volcanoes. Again this would result in different clades of Kaiju living in different places and climes. One part of this question, it is only possible speculate about and that is what the environment is like in this alternative dimension. With right sort of environment or even environments, all kinds of Kaiju be accommodated in places suitable for them. Societies arise when people and presumably sapient Kaiju, have a need to cooperate, to work and live together in reasonable harmony. Usually this means by living together in orderly and cooperative arrangements this advantageous to the members of the society. The advantages can economic or ecological. Living together leads to a better quality and standard of life. It enhances their survival and safety. It provides protection from predators and enemies. Quite likely, like humans there will be a multiplicity of Kaiju societies, social and cultural institutions, and political organizations. The equivalent of our nation states. Farms producing foodstuffs. Manufacturing industries too. Even forms of entertainment, with possibly professional and amateur performers and artists. In principle, Kaiju societies could be just as practical and beneficial as human societies. Certain factors such as the environment(s) in which they exist will also need to be considered. [Answer] Yes it could work. Humans don't normally deal with size differences of the magnitude you're describing, but we deal with plenty of situations of disparate strength, especially in grade school. Ever seen a freshman nerd standing next to the senior quarterback? A 0% chance of winning a physical confrontation is still a 0% chance - doesn't matter if you're 75 kilos heavier or 750 meters taller. As long as your kaiju society can still maintain the rule of law, then this will work out alright. Academics should be okay - the classrooms will just need a huge variety in sizes or be mostly remote. Kaiju will develop a bit more variety in their sports in order to compensate for the differences in size. Most human sports have a great deal of variety in ideal player sizes, just look at the difference between an offensive lineman and a cornerback. The kaiju will just have more extreme versions of this. For all you know, there'll even be a sport where the smallest kaiju are used as the actual ball - probably an ocean game of some sort, for safety reasons. There could be some really fun stuff to do with that general idea - kaiju of various sizes actually participating as equipment in the sport. Some character could be useful just because they're the perfect size for the star player to use as a bat. Or the smallest kaiju play tennis and the biggest ones play football. Whatever. Even humans have weight classes. At some point, the size difference becomes a safety issue in general - humans get along mostly okay with babies, which are small and fragile, but then again we know they eventually grow up. If small kaiju stay small, then they'll need to create their own spaces. There could be some communication issues due to the differences in pitch likely between kaiju of different size classes, but I guess you can just physics hand-wave that. If your society isn't very egalitarian, then you would see social strata develop, mostly based on size. Bigger is probably better. [Answer] Sexual dimorphism exists in the animal kingdom as can be seen for example in [elephant seals](https://en.wikipedia.org/wiki/Elephant_seal) and the [Green Spoonworm](https://en.wikipedia.org/wiki/Bonellia_viridis), but nothing on the scale that you describe exists on Earth and certainly not between individuals of the same sex. The fact that something does not appear on Earth does not rule it out, but it should give pause for thought. I suggest that there is no absolute prohibition on such extreme variation; however it would require some very unusual and extreme selection pressures for such a situation to evolve. Given that your creatures are from another dimension almost any forces might be at work and could well cause this so it seems to be entirely plausible. Note a bigger difficulty would be in physical contact or even communication between humans and the Kaiju as the environment they live in is based on a very different physics. The real problem is in establishing what the alternative physics is, ensuring that it is self-consistent and dreaming up a method whereby there is some mechanism for communication that does not lead to a catastrophic situation. Two types of physics would not sit well together and I suggest would lead to the generation of black holes, gravitational distortions or some other run away effect that would swamp your story. ]
[Question] [ In my world there is a race of humans who are disproportionately female. They are closely derived from and very similar to real-world humans, but are unable to interbreed with the other races as they are too genetically distinct to produce fertile hybrids. They do not reproduce themselves asexually, but rather all the permitted females in a tribe mate with one or a few males, because very few males are even born. The culture is built in no small part from the premise that the vast majority of its people are women, but I want to know just how few males this species can get away with, considering they are genetically isolated and every generation faces a serious potential bottleneck effect. I guessed with gut instinct that one male per hundred females would work, but I'm afraid that's a bit too conservative; for a stronger narrative and more spectacle, I'd also like to know if 1/1,000 would work. For context, the species as a whole probably has a population of between 5-10 million, and are heavily maritime so all tribes have access to each other. [Answer] *You need 5,000 mobile* males to make your population stable, at a minimum This question has already been addressed from a different perspective in recent years, namely around [interstellar generation ships](https://www.popularmechanics.com/space/deep-space/a10369/how-many-people-does-it-take-to-colonize-another-star-system-16654747/) and unlike previous research that looked at minimum viable populations in the hundreds, the new research tends to indicate that we need around 10,000 humans to maintain genetic integrity and avoid in-breeding on a new planet, away from others who could introduce genetic diversity. Halving that figure tells us the number of males your society would absolutely need, but the real problem then is distribution. In your society, if the males stay where they are born, within a few generations everyone is (more or less) a half-sister, genetically speaking. So, given that your population is mobile and has access to all each other's settlements, in order for your society to function your males are best shipped off to random 'other' settlements upon birth and raised by their newly adopted community. This would allow the greatest randomisation and distribution of the gene pool given the minimal seeding opportunities that the females have in their environment. If you have a population of 5 million which is the lower bound in your question, then a ratio of 1:1000 is possible, but it would be at the absolute minimum threshold of viability. Increasing the size of the population, but not the ratio, would lead to enough men to make the society viable and build in some safety protocols around genetic defects within males, sterility, accidents, and the like. That said, such a ratio is going to bring other considerations. Just to maintain zero population growth, each male is going to have to father at least 1000 babies over the course of their 'career'. This is a lot. Put simply, if they father a single child once a week it will take them 20 years to complete their obligations. But, that assumes that every attempt is successful, and that you don't also want to account for infant mortality, disease, disaster, population growth and the like. Let's say that the male is successful only 50% of the time. Let's further say he has to sire 2000 children. That's 40 years of engaging in relations twice a week, minimum. Finally, that's assuming that there aren't false starts; some men (or even women) who turn out to be infertile, and therefore increase the load on the remaining men. On the one hand, men will be revered in this society for the service they provide (no pun intended, seriously) but on the other hand, their ability to pursue interests of their own are now greatly curtailed. Their full time job at this ration would effectively be impregnation and a whole industry / religion / whatever would soon build up around this function, including the necessary distribution of male infants through the broader community of settlements. [Answer] You need to have a think about like humans do you want them to be, socially and sexually? Humans are very bad at getting pregnant. Studies done on American newly weds who were actively trying to have a child (lots of sex, no contraception), showed that it took on average 6 months for them to conceive. Now that's an average, so some of them would have got lucky on their wedding night. But others would have taken much longer than 6 months. So the probability of each mating resulting in a baby is very low if your males and females are physiologically and biochemically identical to humans. However, there are plenty animals which are much better at conceiving. The females come into season*, they mate a few times (perhaps over a day or two), and get pregnant. In mammals, the ultimate success in getting pregnant is the mountain hare, Lepus timidus. The female can mate once and get pregnant twice! She stores some of the sperm* from a spring mating in her reproductive tract, and can use it to conceive a late summer litter. There is also a species of lizard (Uta stansburiana) where a particular male fathered 3 clutches of eggs: once from mating, and then 2 more after he had died, because the female stored his sperm. The ultimate version of this is of course ants, wasps and bees: the queen mates once, and stores the sperm to continually lay fertilised eggs for the rest of her life. These eggs are all female and are workers and new queens. She also lays unfertilised eggs which develop into drones (males). Look up [Haplodiploidy](https://en.wikipedia.org/wiki/Haplodiploidy) for more information. So if you make your humanoids very efficient at mating, and give the women the ability to store sperm, a one night stand with one male can produce an entire lifetime's worth of babies for your woman. The quirk with the mammals and reptiles which do this, is that they may still need to mate for the 2nd and subsequent pregnancies to start. Mating causes the female to ovulate. This is called [Reflex or Induced ovulation](https://en.wikipedia.org/wiki/Induced_ovulation_(animals)). The female hare will mate with any old male for her second litter, and will have both his sperm and the first male's sperm present in her reproductive tract. The first male's sperm has a 'head start' in getting to the eggs. It's not the sperm, its the sex which kicks the process off. So if you want, your women could have female lovers to trigger the second pregnancy and the ones after that. Alternatively, real world humans are spontaneous ovulators: we have a menstrual cycle, and release an egg once every 21 to 35 days. So your women could have sex once, store the sperm and use a bit of it every time they ovulate. The genetic bottleneck may not be as bad as you think. There are plenty species where the males fight and/or display for the right to mate. For instance elephant seals, red deer, birds of paradise, peacocks. The winners are 5% of the male population and they father 95% of the offspring. 15% of the males father the other 5% of the offspring. 80% of the males never, ever mate. Therefore you can have a small number of males keeping your population going. In the situation above, 80% of male genetic diversity is lost every generation, but there is no sign of deer and elephant seals suffering from inbreeding. [Answer] ## Dunbar's Number I love going back to this because it just feels so real. Primitive societies were limited to about 100-150 people, even in modern society we have trouble keeping track of more than that. I'm connected to a thousand or people on social media. I doubt I could give specific details about more than 200 of them and I doubt that more than 200 could give details about me. The theory is our brains aren't wired for that. Up until the steel age, maybe late bronze age, you would need one male for every 50-75 women. (Current breeder and future breeder) At the annual gathering of the clans any sons born in the previous year would be feted and sold to another clan who lacks the future breeder. With writing and transportation becoming more accessible you could have larger groups of women sharing a man. A young vigorous male could perhaps service 1200 women in a year(3-4 times a day), older men perhaps could only handle two clans. Once space age technology is reached, assistive reproduction ICSI would allow one male to serve millions. [Answer] Here's the problems, assuming they're still mostly human: 1. Human females don't advertise (generally speaking) when they're fertile, and you're only looking at conception being even possible for 5 or 6 days per month. So, about 80% of the time, no chance of pregnancy just based on the odds. If you're talking a ratio of 1 to 100, and as mentioned a mature male might be able to pull off twice a day, you're talking 50 days to "service" all the females once. So, just rounding out, say two months. That means the vast majority won't get fertilized based on chance alone. 2. Failure to implant and miscarriages are ridiculously common in humans, with some estimates that up to 90% of fertilized eggs do not result in a baby being born, with most being ejected before the woman even knows she's been fertilized. Even with the lower accepted numbers like 75%, that still means of the few women out of 100 the male has sex with at the right time, at least 3/4s of them or more won't end up with a child. [Answer] The few males, or diversity in general, are not so much the problem per se. While there are many opinions and theories ("research") on that field, the simple truth is that nature doesn't care. Nature will take whatever it is given, it has always done that. Some combinations are more favorable than others, but in the end nature just works with what it has. Will there be some individuals with defects? Well sure, they'll probably die. That's called selection (actually, this may be the very reason why there are so few males. Think Rett syndrome or Bloch-Sulzberger (or anything that's on the X-chromosome). Males who get the allel are never born, they just die in utero). But whatever, some will die, and some will live. Those that live will reproduce. Those with fewer defects will (usually) reproduce better. Nature doesn't care if a few die. In the early days of man, tribes which certainly didn't have 10,000 people wandered to other regions driven by hunger, cold, or whatever reason. They reproduced just fine. Take Rapa Nui as an example if you will, or the American Indians Bering strait theory, whichever. Those tribes (and single families) surely didn't have appropriate numbers which modern research deems necessary, but nature just doesn't care. They reproduced just fine. What's a problem with your distribution is the females, actually. Women tend to synchronize their menstrual cycle when they live together. Which means that all women are fertile at the same time, give or take a day. Which, uh... is a problem. A man produces enough swimmers to be successful once, twice, maybe thrice per day. Everything beyond that is wishful thinking. I mean, sure, he can copulate more often, it's just that the chance of causing a pregnacy goes towards zero. So if you have 60 women on one man, that works out mathematically over the monthly average, but if they're all fertile on next wednesday, then that's truly not the very optimum. [Answer] What you care about is something called [effective population size](https://en.wikipedia.org/wiki/Effective_population_size). This is a term used by population biologists who want a way to quantify the genetic characteristics of some non-ideal population as compared to an ideal one. So a population that goes through bottlenecks or a population with highly variable reproductive success will have a lower effective population size than their actual size because these features of populations increase genetic drift. [Genetic drift](https://en.wikipedia.org/wiki/Genetic_drift) is what we really care about because it’s a measure of how genetic diversity is lost in small populations over time and this is what your population needs to avoid. The effect of unequal sex ratios on effective population size is as follows: $$N\_e = \frac{4N\_mN\_f}{N\_m+N\_f}$$ This tells us that the effective population size $N\_e$ can be calculated from the ratio of males $N\_m$ to females $N\_f$ and that the more imbalanced that ratio is the smaller the effective population size is. For an in-depth explanation of how this formula works see our friends at [biology.se](https://biology.stackexchange.com/questions/41761/effect-of-sex-ratio-on-the-effective-population-size/44296#44296). So now to understand how many males the species can “get away with” we only need to know how large the actual population is and how large the effective population needs to be. If you play around with this formula you will see that as soon as the sex ratio changes significantly from 1 the effective population size drops significantly. This decrease approaches an asymptote of 4x the population of the less frequent sex. This tells us that you can have a hugely imbalanced sex ratio as long as there is some minimum number of the minor sex to achieve a viable effective population size. Now, what is the “minimum viable population”? Frankly, estimates vary and depend on many things. If you look at just the genetics then the answer tends to be in the hundreds. The [estimate of 10,000](https://www.sciencedirect.com/science/article/abs/pii/S0094576513004669) cited in Tim B. II’s answer is on the high end because they are expecting "at least one severe population catastrophe over the 5-generation voyage." That probably isn’t an awful factor to consider in the survival of a population on a planet either, but it’s also not strictly about the genetics of the population either. ]

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